Prevalence, antimicrobial resistance, and genetic lineages of nasal Staphylococcus aureus among medical students at a Spanish University: detection of the MSSA-CC398-IEC-type-C subclade

Medical students could be a potential source of Staphylococcus aureus transmission to patients. This cross-sectional study involved samples collected from both nasal nostrils. Samples were processed for S. aureus recovery; the antimicrobial resistance (AMR) phenotype was determined by disc diffusion assays and the spa types and AMR genotypes by PCR/sequencing. A structured questionnaire was administered to students to collate data related to potential risk factors of nasal colonization. Ninety-eight students were included, 50 % were colonized by S. aureus and 12.2 % by MRSA. The mecA gene was detected in all MRSA isolates. The MSSA-CC398-IEC-type C lineage was found among 16.3 % of nasal carriers, of which t571 was the predominant spa-type. MRSA isolates were ascribed to spa types t2226 (CC5, 12 isolates) and t3444 (new spa type, 1 isolate). All MRSA were multi-drug resistant and MSSA were predominantly resistant to erythromycin-clindamycin (inducible-type, mediated by ermT gene). High rates of S. aureus and MRSA nasal carriages were observed in this study. The predominance of the CC398 lineage among MSSA (emergent invasive lineage) represent a relevant finding of public health concern. The role of medical students as potential source of MRSA and MSSA-CC398 transmissions in hospital and community needs to be elucidated in detail.

Molecular characterization and antimicrobial resistance of nasal Staphylococcus aureus in the community of Kabul

OBJECTIVES

This study aimed to investigate the prevalence and molecular characteristics of community methicillin-resistant Staphylococcus aureus (MRSA) nasal carriage among students at Kabul University.

METHODS

Nasal swabs were collected from anterior nares of 150 healthy non-medical students at Kabul University. Antimicrobial susceptibility testing was performed on all S. aureus isolates, and all detected MRSA isolates were then confirmed by mecA/mecC polymerase chain reaction and characterized using DNA microarray.

RESULTS

A total of 50 S. aureus strains were isolated from the anterior nares of the 150 participants. The prevalence of S. aureus and MRSA nasal carriage among Kabul students was 33.3% and 12.7%, respectively. Seven (36.8%) MRSA isolates and 8 (25.8%) methicillin-susceptible S. aureus (MSSA) isolates were multidrug-resistant (i.e. resistant to at least three different antimicrobials tested). All MRSA isolates (n = 19) were susceptible to linezolid, rifampicin, and fusidic acid. Seven MRSA clones, belonging to four clonal complexes (CCs), were identified. The most commonly identified clone was CC22-MRSA-IV TSST-1-positive, which accounted for 63.2% (12/19) of MRSA isolates. SCCmec typing showed that most MRSA strains harboured SCCmec type IV (94.7%). Thirteen (68.4%) MRSA isolates carried the TSST-1 and 5 (26.3%) PVL genes.

CONCLUSION

Our findings revealed the relatively high prevalence of MRSA nasal carriers in the community in Kabul, with the predominance of the CC22-MRSA-IV TSST-1-positive clone and frequent multidrug resistance among these isolates.

Staphylococcus aureus nasal colonization level and intracellular reservoir: a prospective cohort study

Staphylococcus aureus is a major pathogen in humans. The nasal vestibule is considered as the main reservoir of S. aureus. However, even though the nasal cavity may also be colonized by S. aureus, the relationships between the two sites are still unclear. We conducted a prospective study in humans to assess the S. aureus colonization profiles in the vestibule and nasal cavity, and to investigate the presence of intracellular S. aureus in the two sites. Patients undergoing ear, nose, and throat surgery were swabbed during endoscopy to determine S. aureus nasal load, genotype, and presence of intracellular S. aureus. Among per-operative samples from 90 patients, the prevalence of S. aureus carriage was 32.2% and 33.3% in the vestibule and the nasal cavity, respectively. The mean S. aureus load was 4.10 and 4.25 log₁₀ CFU/swab for the nasal vestibule and nasal cavity, respectively (P > 0.05). Genotyping of S. aureus revealed that all nasal strains isolated from a given individual belong to the same clonal complex and spa-type. An intracellular carriage was observed in 5.6% of the patients, all of whom exhibited a S. aureus vestibule load higher than 3 log₁₀ CFU/swab. An intracellular niche was observed in the vestibule as well as in the nasal cavity. In conclusion, the nasal cavity was also found to be a major site of S. aureus carriage in humans and should draw attention when studying host-pathogen interactions related to the risk of infection associated with colonization.

Phenotypic and molecular characterization of Staphylococcus aureus isolates conducted in nares of psoriatic patients attending a public hospital in Argentina

Although Staphylococcus aureus increases its relative abundance in psoriasis when compared with the microbiome of healthy subjects, it is not the most important microorganism underlying this disease. However, there is scant data on the role and molecular features of S. aureus strains in psoriasis; therefore, the aim of this study was to evaluate nasal carriage of this microorganism, its phenotypic and molecular characteristics as well as the impact of host factors on its carriage in psoriatic patients. The presence of S. aureus was analyzed in nasal swabs from 46 healthy volunteers and 50 psoriatic patients by conventional microbiology techniques. Nasal carriage of S. aureus was higher in psoriatic patients than in the control group (37.24% vs 22.98%, respectively), being associated to sex (male), age (adults) and severity of the disease (more frequent in moderate and severe cases). Determination of antibiotic resistance detected 12% of β-lactam resistant isolates, with variable accompanying resistance to macrolides, aminoglycosides and fluoroquinolones. No resistance to rifampicin, vancomycin, mupirocin or trimethoprim/sulfamethoxazole was found. A preliminary molecular characterization of the isolates was performed by PCR amplification of virulence genes. Molecular characterization of the strains did not reveal a predominant strain in psoriatic patients. Although we established host factors related to increased carriage of S. aureus in psoriatic patients, we could not establish the predominance of one type of strain. Genomic and transcriptomic analysis of the isolated strains would be necessary to address this point.

Nasal colonization by potential bacterial pathogens in healthy kindergarten children of Nepal: a prevalence study

INTRODUCTION

In low- and middle-income countries including Nepal, respiratory tract infection (RTI) is considered as one of the most prominent public health problems in children. Multiple carriage of respiratory pathogens is common in children, especially in preschoolers as they are easily transmitted through close contact and poor hygienic condition. Thus, this research is based on the study of prevalence, co-existence, associated factors and antibiogram of nasal isolates among healthy preschoolers.

METHODS

The study was conducted in four randomly selected kindergarten schools (two government run and two private run) of Bhaktapur Municipality. Out of a total 140 students, 136 eligible participants of age group 2-5 years old were involved in the study. Nasal swab was collected for the isolation of five target isolates (Staphylococcus aureus, Streptococcus pneumoniae, Moraxella catarrhalis, Haemophilus influenzae and Haemophilus parainfluenzae) and their antibiotic resistance determination.

RESULTS

Of 136 participants involved, 128 (94.5%) were positive for carriage of at least one of the target bacteria. The most common isolate was M. catarrhalis 62.5% (80/128) followed by S. aureus 43.0% (55/128). There was a significant difference in bacterial carriage with respect to type of school (p value<0.05, OR=0.50, CI=0.20-0.90). Regarding bacterial co-existence, the most common co-existence was of S. aureus and M. catarrhalis & S. pneumoniae and M. catarrhalis 48.8%. Multiple logistic regression analysis showed that S. aureus was negatively associated with S. pneumoniae, M. catarrhalis and H. influenzae and S. pneumoniae was positively associated with M. catarrhalis and H. influenzae. Multidrug resistance was seen in 63 isolates (29.4%).

CONCLUSIONS

Nepalese kindergarten children are at a high risk of respiratory tract infection by multidrug resistant bacteria.

Insights into the epidemiology of community-associated methicillin-resistant Staphylococcus aureus in special populations and at the community-healthcare interface

The current epidemic proportions of infections caused by Staphylococcus aureus strains and especially by methicillin-resistant S. aureus (MRSA) are one of today's many threats to global public health, particularly in underdeveloped countries where significant gaps on the subject exist. The rapid spread and diversification of pandemic clones that exhibit remarkably increasing virulence and antimicrobial resistance pose a risk to the effective prevention and treatment of a wide range of infections. Undoubtedly, the remarkable versatility involving the pathogenesis and resistance of these bacteria is perpetuated through geographic and temporal factors inherent to clonal evolution and is reflected in the dramatic epidemiological changes of MRSA which, after decades prevailing in healthcare settings, have emerged in the community. Denominated community-associated [CA]-MRSA, these strains are particularly prevalent in some population groups, facilitating the spread of successful clones that are potentially capable of triggering severe community-acquired infections. Therefore, a broad approach to local epidemiological aspects in less studied regions, but nonetheless at latent risk of endemic spread that may reach global proportions, is necessary. In Brazil, despite limited molecular epidemiology data, CA-MRSA strains predominantly characterized as SCCmec IV, often classified as CC30-ST30, CC5-ST5 and CC8-ST8, seem to be spreading across different population groups in different regions of the country. Another important fact addressed in this review is the identification of the ST398-MRSA-IV/V clone and methicillin-susceptible S. aureus (MSSA) in healthy individuals from the community. Although susceptible to methicillin, the ST398 clone is associated with severe infections in humans and animals, denominated livestock-associated MRSA. It is therefore important to encourage assertive actions by all government sectors and by society, with a reassessment of current public health measures in light of the new perspectives arising from the scientific and epidemiological data on MRSA.

Determination of nasal carriage and skin colonization, antimicrobial susceptibility and genetic relatedness of Staphylococcus aureus isolated from patients with atopic dermatitis in Szczecin, Poland

BACKGROUND

Atopic dermatitis (AD) is one of the most frequent chronic and inflammatory skin condition. AD is characterized by damaged epidermal barrier, xerosis and pruritus of eczematous skin lesions which tend to flare. The duration and frequency of exacerbation of AD symptoms markedly affects the quality of patient life. AD results from the interplay between host genetics, immunity, and environmental factors, however the detailed pathogenesis of this disease is still not entirely cleared. Furthermore, disturbances of the skin microbiota and skin functional impairment predispose to secondary skin infections. Staphylococcus aureus colonizes skin and mucous membranes of 20 to 80% of healthy individuals and of 90% of patients with AD in whom this bacterium is accounted as an important AD exacerbating factor. It is also proven, that S. aureus nasal carriage significantly increases the risk for self-transmission and endogenous infection. In the current study the presence of S. aureus either in nasal vestibule and on lesioned skin of 64 patients with AD enrolled in 10-year autovaccination program was determined. The genetic relatedness of 86 S. aureus isolated from patients nose and skin using Pulsed Field Gel Electrophoresis (PFGE) and antimicrobial susceptibility of all strains to methicillin, erythromycin, clindamycin, mupirocin, gentamicin, amikacin, tetracycline, chloramphenicol and cotrimoxazole was also evaluated.

RESULTS

In total 23 PFGE genotypes and 24 unique patterns were distinguished. 34 patients were S. aureus nasal carriers. Simultaneous presence of S. aureus in nose and on affected skin was found in 16 carriers colonized by indistinguishable or potentially related S. aureus vs 2 carriers colonized with non-related S. aureus in nasal vestibule and on skin. 4 isolates were methicillin resistant (MRSA) among which 3 showed constitutive MLSB resistance phenotype and remaining one was resistant to tetracycline and chloramphenicol. In 4 isolates inducible MLSB resistance phenotype was found, one of them was additionally resistant to tetracycline. 7 S. aureus were mupirocin resistant among them 3 - isolated from one patient, were resistant simultaneously to tetracyclines and chloramphenicol. 7 strains demonstrated resistance to chloramphenicol and susceptibility to all tested antimicrobial agents. The susceptibility to gentamicin, amikacin and cotrimoxazole among all examined S. aureus was confirmed.

CONCLUSION

The obtained results indicated non-clonal structure of S. aureus circulating in AD patients. PFGE results showed the clonal-structure of vast majority of S. aureus isolated from nose and skin from nasal carriers what may prove the autoinfection in these patients. All examined patients the moderate or strong severity of AD was reported. Susceptibility to most antibiotics among isolated strains was also observed.

Molecular characteristics of Staphylococcus aureus strains isolated from nasal samples of sixth year medical students during their pediatric services practices

Background

Methicillin-resistant Staphylococcus aureus (MRSA) strains are prevalent in healthcare services. Medical students are at risk for MRSA carriage, subsequent infection and potential transmission of nosocomial infection.Few studies have examined MRSA carriage among medical students.

Methods

In this prospective cohort study, between July 2016 and June 2017, two nasal swab samples were taken per student 4 weeks apart during their pediatric internship. MRSA typing was performed by staphylococcal cassette chromosome mec (SCCmec) types, Panton Valentine leukocidin (PVL) encoding genes.

Results

A total of 239 sixth year medical students, 164 (68.6%) male (M/F:2.1),with median age 25 years (min–max; 23–65 years) were included in this prospective cohort study. Among 239 students, 17 students (7.1%) were found to be colonized with methicillin-sensitive S. aureus (MSSA) at the beginning of pediatric internship. After 4 weeks, at the end of pediatric internship totally 52 students were found to be S. aureus colonized (21.8%). Three of 52 S. aureus isolates were MRSA (1.3%) and the rest was MSSA (20.5%), all were PVL gen negative. Two of three MRSA isolates were characterized as SCCmec type IV, one isolate was untypeable SCCmec. Nasal carriage of S. aureus increased from 7.1% to 21.5% (p < 0.001). Nasal S. aures colonization ratio was higher in students working in pediatric infectious disease service (p = 0.046). Smoking was found to be associated with a 2.37-fold [95% CI (1.12–5.00); p = 0.023] and number of patients in pediatric services was 2.66-fold [95% CI (1.13–6.27); p = 0.024] increase the risk of nasal S. aureus colonization. Gender was not found to increase risk of MRSA carriage.

Conclusion

MSSA nasal carriage increased at the end of pediatric internship and significantly high in students working in pediatric infectious diseases services. Smoking and high number of patients in pediatric services significantly increase S.aureus colonization.

NASAL CARRIAGE OF MULTI-DRUG RESISTANT PANTON VALENTINE LEUKOCIDIN POSITIVE STAPHYLOCOCCUS AUREUS IN HEALTHY INDIVIDUALS OF TUDUN-WADA, GOMBE STATE, NIGERIA

Background:

Panton-Valentine Leucocidin (PVL)-producing Staphylococcus aureus strains have been implicated in serious community-associated invasive infections and their increasing multidrug resistance is a major global health concern. Thus, we investigated the prevalence of the PVL gene and the antimicrobial resistance profile of nasal S. aureus isolates from healthy adults in Tundu-Wada, Gombe State of Nigeria.

Methods and Materials:

A total of 262 nasal samples from healthy adults were obtained and cultured. The isolates were identified as S. aureus by standard morphological and biochemical methods alongside with the Polymerase Chain Reaction (PCR) amplification of their 16S rRNA gene. Antimicrobial susceptibility testing was performed by the disc diffusion technique and the presence of mecA and PVL genes was determined by PCR analysis.

Results:

The overall nasal colonization of S. aureus was 17.6%. The prevalence of haemolysin and biofilm production among the isolates was 25(54.3%) and 42(91.3%), respectively. Only 2(4.3%) and 5(10.9%) possessed mecA and PVL genes respectively but none of the isolates harboured these two genes. All the isolates were resistant to amoxicillin but were highly susceptible (93.7%) to gentamicin. The prevalence of multi-drug resistance (MDR) among the isolates was M 45.7% and all PVL-producing isolates were MDR while one of the isolates with mecA gene exhibited extensive-drug resistance (XDR).

Conclusion:

This is the first report of nasal colonization of MDR PVL-producing S. aureus in healthy adults in Gombe, Northeastern Nigeria. This study highlights the importance of routine surveillance of healthy populations to provide useful strategies for controlling the spread of virulent multidrug-resistant organisms within the community.

Methicillin-resistant Staphylococcus aureus nasal carriage among janitors working in hospital and non-hospital areas: a comparative cross-sectional study

BACKGROUND

Nasal colonization of Methicillin-resistant Staphylococcus aureus (MRSA) plays a key role in the epidemiology and pathogenesis of both healthcare-associated and community-acquired MRSA infections in various populations. Screening of MRSA nasal colonization is important in the prevention and control of infection and may provide useful information to guide antimicrobial therapy. This study aimed to determine nasal carriage of MRSA, its antimicrobial susceptibility pattern, and associated factors among janitors working in hospital & non-hospital areas at the University of Gondar, Northwest Ethiopia.

METHODS

A comparative cross-sectional study was carried out in a total of 436 study participants (221 hospital and 215 non-hospital janitors) from January to May 2019. The study participants were sampled using a simple random sampling technique. Data on socio-demographic characteristics and associated factors were collected through face to face interviews using a structured questionnaire. Nasal swabs were collected and inoculated into Mannitol salt agar. MRSA was detected using cefoxitin (30 µg) disc and an antibiotic susceptibility test was done using the disc diffusion method. Data were entered and analyzed using SPSS version 20 statistical package. P value ≤ 0.05 was considered as statistically significant.

RESULTS

The overall prevalence of S. aureus was 101/436 [23.2%, (95% CI: 19.3-27.8)], of which, 29.4% (65/221) were isolated from hospital and 16.7% (36/215) non-hospital janitors. The prevalence of MRSA was 4.8% (21/436) [95% CI: 3.0-6.9]; of these, 8.1% (18/221) of the isolates were from the hospital and 1.4% (3/215) non-hospital janitors, while methicillin-sensitive S. aureus (MSSA) in hospital & non-hospital janitors were 49 (22.2%) and 31 (14.4%), respectively. Among the MRSA isolates, 52.4% (11/21) were multi-drug resistant. Of these, 42.9% (9/18) were isolated from hospital and 66.7% (2/3) non-hospital janitors. Hence, nasal carriage of MRSA was significantly associated with hospitalization within the preceding year (AOR = 3.15, CI = 1.13-8.71).

CONCLUSION

The present study revealed that high MSSA and MRSA were isolated from the hospital as compared to non-hospital janitors and high rates of antibiotics resistance were recorded in the hospital janitors. Consequently, hospitalizations were significantly associated with MRSA. Accordingly, regular screening of carriers in apparently healthy janitors is required for the prevention of nosocomial infections.

Multidrug-resistant Staphylococcus aureus nasal carriage among HIV-positive outpatients in Guangzhou, China: Prevalence, risk factors, phenotypic and molecular characteristics

INTRODUCTION

Data on comprehensive characterization of multidrug-resistant (MDR) Staphylococcus aureus (S. aureus) carriage in human immunodeficiency virus (HIV)-positive patients are limited. The objective of the present study is to determine the prevalence, risk factors, phenotypic and molecular characterization of MDR S. aureus isolated from HIV-positive population.

METHODS

A cross-sectional study was conducted to determine the characteristics of MDR S. aureus nasal carriage among HIV-positive outpatients in an HIV clinic from June to August 2017. Nasal swabs and risk factor data of the enrolled HIV-positive outpatients were collected. Phenotypic and molecular characteristics of MDR and non-MDR S. aureus isolates were analyzed. Risk factors for nasal carriage with MDR S. aureus were estimated by logistic regression. The relationship between phenotypic and molecular characteristics of S. aureus isolates was assessed by the correspondence analysis.

RESULTS

Overall, 1001 HIV-positive outpatients were included. The prevalence of MDR S. aureus nasal carriage was 15.18% (152/1001), and the proportion of multidrug resistance among S. aureus isolates was 60.08% (152/253). Having a history of respiratory tract infection was the risk factor for MDR S. aureus nasal carriage (adjusted odds ratio = 1.90, 95% confidence interval: 1.25-2.89). Multidrug resistance of S. aureus isolates was in good corresponding relationships with clonal complex (CC)5, CC15, CC59 and CC398.

CONCLUSIONS

We found high burden of multidrug resistance among S. aureus isolated from HIV-positive outpatients, particularly in those who had upper respiratory tract infection. Moreover, CC59 and CC398 are highly related to multidrug resistance of S. aureus isolates.

Nasal carriage of Staphylococcus aureus in farm animals and breeders in north of Morocco

BACKGROUND

The objectives of this study were to determine for the first time, in Morocco, the nasal carriage rate, antimicrobial susceptibility profiles and virulence genes of Staphylococcus. aureus isolated from animals and breeders in close contact.

METHODS

From 2015 to 2016, 421 nasal swab samples were collected from 26 different livestock areas in Tangier. Antimicrobial susceptibility phenotypes were determined by disk diffusion according to EUCAST 2015. The presence of nuc, mecA, mecC, lukS/F-PV, and tst genes were determined by Polymerase Chain Reaction (PCR) for all isolates.

RESULTS

The overall S. aureus nasal carriage rate was low in animals (9.97%) and high in breeders (60%) with a statistically significant difference, (OR = 13.536; 95% CI = 7.070-25.912; p < 0.001). In general, S. aureus strains were susceptible to the majority of antibiotics and the highest resistance rates were found against tetracycline (16.7% in animals and 10% in breeders). No Methicillin-Resistant S. aureus (MRSA) was detected in animals and breeders. A high rate of tst and lukS/F-PV genes has been recovered only from animals (11.9 and 16.7%, respectively).

CONCLUSION

Despite the lower rate of nasal carriage of S. aureus and the absence of MRSA strains in our study, S. aureus strains harbored a higher frequency of tst and lukS/F-PV virulence genes, which is associated to an increased risk of infection dissemination in humans. This highlights the need for further larger and multi-center studies to better define the transmission of the pathogenic S. aureus between livestock, environment, and humans.

Characterization of peripheral blood mononuclear cells gene expression profiles of pediatric Staphylococcus aureus persistent and non-carriers using a targeted assay

Defects in innate immunity affect many different physiologic systems and several studies of patients with primary immunodeficiency disorders demonstrated the importance of innate immune system components in disease prevention or colonization of bacterial pathogens. To assess the role of the innate immune system on nasal colonization with Staphylococcus aureus, innate immune responses in pediatric S. aureus nasal persistent carriers (n = 14) and non-carriers (n = 15) were profiled by analyzing co-clustered gene sets (modules). We stimulated previously frozen peripheral blood mononuclear cells (PBMCs) from these subjects with i) a panel of TLR ligands, ii) live S. aureus (either a mixture of strains or stimulation with respective carriage isolates), or iii) heat-killed S. aureus. We found no difference in responses between carriers and non-carriers when PBMCs were stimulated with a panel of TLR ligands. However, PBMC gene expression profiles differed between persistent and non-S. aureus carriers following stimulation with either live or dead S. aureus. These observations suggest that individuals susceptible to persistent carriage with S. aureus may possess differences in their live/dead bacteria recognition pathway and that innate pathway signaling is different between persistent and non-carriers of S. aureus.

Nasal carriage of methicillin-resistant Staphylococcus aureus (MRSA) among undocumented migrants and uninsured legal residents in Amsterdam, the Netherlands: a cross-sectional study

BACKGROUND

Nasal carriage of methicillin-resistant Staphylococcus aureus (MRSA) is associated with an increased risk of infection. Colonization with MRSA is observed in < 1% of the general Dutch population. Increased risk for MRSA carriage is known to occur in several key groups, one of which is asylum seekers. However, little is known about MRSA carriage among undocumented migrants and uninsured legal residents. This study aimed to determine the prevalence of nasal MRSA carriage among these groups in Amsterdam, the Netherlands.

METHODS

In this cross-sectional study, between October 2018 and October 2019, undocumented migrants and uninsured legal residents aged 18 years or older who were able to understand one of the study languages were recruited at an NGO health care facility in Amsterdam, the Netherlands, for general practitioner (GP) consultations. Participants were asked questions on demographics, migration history, antibiotic use and other possible risk factors for MRSA carriage and were screened for nasal MRSA carriage by selective culturing e-swabs. Characteristics of MRSA-negative and MRSA-positive participants were compared using univariable logistic regression analysis with Firth's correction.

RESULTS

Of the 3822 eligible patients, 760 were screened for nasal MRSA carriage (19.9%). Of the 760 participants, over half were male (58%; 442/760) and originated mainly from Africa (35%; 267/760), Asia (30%; 229/760) and North or South America (30%; 227/760). In total, 705/760 participants (93%) were undocumented migrants and 55/760 (7%) were uninsured legal residents of Amsterdam. The overall prevalence of nasal MRSA carriage was 2.0% (15/760) (95%CI 1.1 to 3.2%), with no difference between undocumented migrants (14/705) (2.0, 95%CI 1.1 to 3.3%) and uninsured legal residents (1/55) (1.8, 95%CI 0.1 to 9.7%). Genotyping showed no clustering of the 15 isolates. MRSA carriage was not associated with sociodemographic, migration history or other possible risk factors. Nevertheless, this study had limited power to detect significant determinants. Three participants (3/15; 20%) harbored Panton-Valentine leukocidin (PVL)-positive isolates.

CONCLUSION

Even though our study population of undocumented migrants and uninsured legal residents had a higher prevalence of nasal MRSA carriage compared to the general Dutch population, the prevalence was relatively low compared to acknowledged other high-risk groups.

Performance of the Hologic Panther Fusion® MRSA Assay for the nasal screening of methicillin-sensitive and methicillin-resistant Staphylococcus aureus carriage

Staphylococcus aureus (SA) nasal carriage screening is usually based on either culture or molecular biology. The aim of the study was to evaluate the performance of the Panther Fusion® MRSA Assay (PF) that proposes a complete automation of the molecular screening for MSSA and MRSA carriage. Four hundred thirty-four nasal samples collected on ESwab™ were screened using PF. Results were compared with standard culture on BBL™ CHROMagar™ Staph aureus and chromID® MRSA agar. Discordant results were analyzed with additional techniques: Xpert SA Nasal Complete on GeneXpert (GX), culture on selective agar after 24 h in broth enrichment, and, if necessary, characterization of mec gene and SCCmec cassette using DNA microarray. The PF presented an overall agreement of 97.5% for SA detection and 97.9% for MRSA detection. Furthermore, 7.1% (31/434) of the samples were SA-negative in primary culture but SA-positive using PF and GX, confirming the greater sensitivity of molecular tests compared with culture. Of note, 4 out of 30 MRSA-positive samples were not detected due to an atypical SCCmec cassette, while 2 samples were falsely detected as MRSA due to co-colonization with a MSSA drop-out strain and a methicillin-resistant coagulase-negative staphylococcal strain. Considering all results, the PF instrument appears as a reliable and rapid (< 3 h) package for MSSA/MRSA nasal screening. This technology using random access capability and direct sampling of the primary container is innovative and corresponds therefore to a new step in complete molecular biology automation in bacteriology.

Methicillin-resistant Staphylococcus aureus nasal colonization among HIV-infected patients in Taiwan: prevalence, molecular characteristics and associated factors with nasal carriage

Background

To evaluate nasal carriage, antibiotic susceptibility and molecular characteristics of methicillin-resistant Staphylococcus aureus (MRSA), as well as the risk factors of MRSA colonization, in human immunodeficiency virus (HIV)-infected patients in northern Taiwan.

Methods

From September 2014 to November 2015, HIV-infected patients seeking outpatient care at four hospitals were eligible for this study. A nasal specimen was obtained from each subject for the detection of S. aureus and a questionnaire was completed by each subject. MRSA isolates once identified were characterized.

Results

Of 553 patients surveyed, methicillin-susceptible S. aureus (MSSA) was detected in 119 subjects (21.5%) and MRSA in 19 subjects (3.4%). Female gender, injection drug use, smoking, hepatitis C virus carrier, cancer and antibiotic use within 1 year were positively associated with MRSA colonization. By multivariate analysis, only cancer (adjust odds ratio (aOR) 7.78, [95% confidence interval (CI), 1.909–31.731]) and antibiotic use within 1 year (aOR 3.89, [95% CI, 1.219–12.433]) were significantly associated with MRSA colonization. Ten isolates were characterized as sequence type (ST) 59/staphylococcal chromosome cassette (SCC) IV or V_T, endemic community strains in Taiwan, four isolates as ST 8/SCCmec IV (USA 300) and one isolate as ST 239/SCCmec IIIA, a hospital strain. All the community-associated MRSA isolates were susceptible to trimethoprim-sulfamethoxazole (TMP-SMX).

Conclusions

Nasal MRSA carriage in HIV-infected patients seeking outpatient care was low (3.4%) in northern Taiwan. Most of the colonizing isolates were genetically endemic community strains and exhibited high susceptibility to TMP-SMX and fluoroquinolones. Cancer and antibiotic use within 1 year were associated with MRSA colonization.

Elimination of Staphylococcus aureus nasal carriage in intensive care patients lowers infection rates

This study surveys the clinical relevance of the nasal Staphylococcus aureus colonization status on intensive care unit (ICU)-acquired S. aureus infections and compares molecular characteristics of isolates from the nose and infectious sites. The 390 patients included comprised 278 non-carriers and 112 carriers. Among the carriers, 56 were decolonized with mupirocin. Decolonization was verified through a second (negative) culture. Spa typing and virulence gene profiling were performed for all isolates. Twenty six S. aureus infections were detected in the carriage group and 20 in the non-carriage group. Eighteen of these 26 (69.2%) infections were among carriers, and 8 of these 26 (30.8%) infections occurred among decolonized carriers (p = 0.02). Overall, 31/112 (27.7%) of the colonized patients and 25/46 (60.1%) of infection were due to methicillin-resistant S. aureus (MRSA). The highest frequency virulence genes were sea and hlg (both 100%) in nasal isolates and sea, hlg, fnb, and clf (100%) for infectious isolates. t030 was the most abundant spa type overall. S. aureus carriers were more likely to develop S. aureus infection compared with decolonized and non-carrying patients. The sources of ICU S. aureus infection appear to be exogenous mostly, and a predominant clone (spa type 030) plays an important role. We confirm that nasal mupirocin treatment prevents ICU infections even when there is an increased prevalence of nosocomial MRSA.

Molecular characteristics of methicillin-resistant Staphylococcus aureus nasal carriage from hospitalized patients and medical staff in Isfahan, Iran

OBJECTIVES

Nasal carriage of methicillin-resistant Staphylococcus aureus (MRSA) has been accounted as one of the main risk factors for the development of complicated nosocomial infections. The present study aimed to determine nasal carriage rate, antimicrobial susceptibility pattern and molecular characteristics of MRSA isolates.

METHODS

This cross-sectional study was performed within 6 months period from July 2015 at 3 hospitals of Isfahan, Iran. Totally, 326 nasal samples were collected by cotton sterile swab from the nasal cavity of participants. Standard microbiological methods were used for identification S. aurues and MRSA isolates. Antibiotic susceptibility pattern was determined by the disc diffusion method according to the CLSI recommendation. Determination of SCCmec typing, agr groups, and virulence genes were performed by PCR method.

RESULTS

Overall, 23.6% of cases were S. aureus carriers including, 23.4% (25/107) of HCWs and 23.7% (52/219) of patients. The rate of MRSA nasal carriages among patients was found to be 51.9% and 16% in HCWs. The highest levels of resistance among MRSA isolates were against ampicillin (93.5%) and tetracycline (83.4%); while, the most effective antibiotics were vancomycin and co-trimoxazole with 100% and 71%, susceptibility. The presence of hla and pvl genes was detected in 80.6% and 3.2% of MRSA isolates, respectively. SCCmec types I, III, IV and V were found in 16.1%, 25.8%, 25.8%, and 16.1% of isolates, respectively. Moreover, agr group I was the predominant type with 43.3.

CONCLUSION

Our results showed a high rate of MRSA colonization in hospitalized patients which remains a significant healthcare problem in our region.

aureus nasal carriage among hospital workers

OBJECTIVES

Thirty percent of the general population are Staphylococcus aureus nasal carriers. It has been shown that this increases with repeated contact with patients, but it is not known whether all categories of healthcare workers are at equal risk of carriage. We aimed to explore S. aureus nasal carriage among healthcare professionals.

METHODS

Prospective study conducted in two French university hospitals in 2014 and 2016. Volunteers were screened for S. aureus nasal carriage. Profession and hygiene habits were collected. Based on the results of this initial study, a second study focused on semi-skilled workers and biomedical equipment technicians (BETs) only; participants were given education on the basic rules of hygiene, then re-screened three months later.

RESULTS

In the initial study, 38.8% of the 436 participants were detected as nasal carriers. There was a significant difference in nasal carriage according to professional category (p < 0.0001); the lowest was found among administrative agents (17.3%), followed by healthcare providers (37.4%), laboratory technicians (37.6%). The greatest proportion was found among semi-skilled workers and BETs (52.9%). Spa-typing ruled out the hypothesis of a single clone dissemination among colleagues. After the three-month hygiene awareness campaign, all re-screened individuals remained positive, and with their respective initial strain.

CONCLUSIONS

To the best of our knowledge we report here for the first time that semi-skilled workers and BETs are specifically more at risk of S. aureus nasal colonisation. This striking finding urges hospital hygiene departments to evaluate this specific professional category and implement strategies to improve hygiene awareness.

Staphylococcus aureus nasal carriage among homeless population in Lisbon, Portugal

Methicillin-resistant Staphylococcus aureus (MRSA) nasal carriage is a major risk factor for infection, namely among populations in the community with inherent prompting factors, such as the homeless. In Portugal, there are no data on S. aureus/MRSA nasal carriage among the homeless community. A total of 84 homeless individuals living in Lisbon (34 with no permanent address and 50 living in shelter) were nasally screened for S. aureus/ MRSA. All isolates were characterized to determine antimicrobial susceptibility and clonal type. A total of 43 (51.2%) S. aureus carriers were identified, including a single individual colonized with MRSA (1.2%). S. aureus carriage rate was higher among individuals with no permanent address (58.8% versus 46%), younger (45.7 ± 12.7 versus 52.5 ± 10.8 years), and with diagnosis of asthma (9% versus 0%). The single MRSA belonged to the EMRSA-15 clone (PFGE D, ST15-SCCmec IVh, and spa type t790). Almost half of the methicillin-susceptible S. aureus (MSSA) isolates (41.9%, n = 18) belonged to two major clones, ST398-t1451 (n = 13) and ST30-t399/t11980/t12808 associated with PFGE I (n = 5). A high proportion of isolates showed non-susceptibility to mupirocin (64%), erythromycin (45%), and fusidic acid (20%) and induced resistance to clindamycin (39%). None of the isolates harboured PVL. Our results suggest that the homeless population of Lisbon does not constitute a reservoir of MRSA in the community, but harbour the highly transmissible ST398-t1451 MSSA lineage.

Frequency of nasal carriage of Staphylococcus Aureus among health care workers at a Tertiary Care Hospital

Objective

To determine the frequency of Methicillin resistance staphylococcus aureus (MRSA) and identification of drug susceptibility for MRSA isolates among health care workers (HCWs) of a tertiary care hospital of South Punjab Pakistan.

Methods

We included 225 HCWs including laboratory staff, doctors, nurses and paramedical staff in this cross-sectional study. The study was conducted in Nishtar medical university/Hospital Multan. The study duration was July-2016 to April-2017. HCWs having no signs of infections and any other systemic disease were included in this study. We used sterile nasal swab sticks for sample collection for determination of S. aureus prevalence. All these samples were processed in the laboratory for MRSA, methicillin sensitive S. aureus (MSSA) and for antimicrobial sensitivity of S. aureus. Chi-square test was used for comparison of frequency of MRSA and MSSA between different HCWs by assuming p-Value ≤0.05 as significant difference.

Results

There were 65.3% (147) female participants and only 34.7% (78) male participants. S. aureus was diagnosed in the nasal flora of 24% (54) participants, out of which 9.3% (21) were MRSA positive and remaining 14.7% (33) were MSSA positive. There was no significant difference in frequency of MRSA and MSSA among different HCWs (p-value 0.79). Amikacin and vancomycin were 100% sensitive for MRSA and MSSA. Clindamycin and ciprofloxacin was 80.9% (17) and 71.4% (15) sensitive for MRSA and 100% and 84.8% (28) for MSSA respectively. While oxacillin and Cefoxitin were 100% (21) resistant for MRSA and sensitive for MSSA.

Conclusion

Prevalence of MRSA and MSSA is high among HCWs in Pakistan. Amikacin, vancomycin and clindamycin have high sensitivity for MRSA and can be used for empirical treatment of MRSA in suspected patients.

High prevalence of methicillin resistant and enterotoxin gene-positive Staphylococcus aureus among nasally colonized food handlers in central Iran

This study defined the prevalence of enterotoxin gene-positive Staphylococcus aureus strains among food handlers and non-food processing healthy nasal S. aureus carriers in central Iran. Meticillin-resistant S. aureus (MRSA) strains were diagnosed by cefoxitin disk diffusion. PCR was used to detect the mecA, Sa442, and enterotoxin genes. Out of the 1113 food handlers, 224 (20.1%) were nasal carriers of S. aureus and 157 (70.1%) of these isolates were positive for one or more enterotoxin genes. The most prevalent enterotoxin gene was sei (40.2%), followed by seg (35.3%), sea (23.5%), seb (15.2%), sec (5.5%), and seh (2.7%). See and sed genes were not found. Sixty seven (42.7%) of enterotoxin gene-positive isolates possessed a single enterotoxin gene, and 64 (40.8%), 23 (14.7%), and 3 (1.9%) contained two, three, or four enterotoxin genes, respectively. The most frequently detected gene combination was sei/seg (n = 35, 22.3%). Thirty seven (16.5%) isolates were diagnosed as MRSA, and 27 (73%) of these strains were positive for at least one enterotoxin gene. Out of 546 healthy controls, 100 individuals were identified as S. aureus nasal carriers; among the strains, 39 (39%) were positive for at least one enterotoxin gene. Only one (1%) CA-MRSA was identified among the strains from the volunteers. A high prevalence of meticillin resistant and enterotoxin-positive S. aureus were documented in food handlers. We suggest that this may be due to the frequent handling of contaminated foodstuffs and that this is possibly related to the elevated frequencies of acquired staphylococcal food poisoning in this population.

Prevalence and molecular characteristics of methicillin-resistant Staphylococcus aureus among nasal carriage strains isolated from emergency department patients and healthcare workers in central Taiwan

BACKGROUND AND OBJECTIVE

Screening and identification of methicillin-resistant Staphylococcus aureus (MRSA) carriage are helpful for controlling MRSA dissemination in hospitals. The aim of our study was to determine the prevalence of nasal carriages and diversity of MRSA among patients and healthcare workers (HCWs) at two regional hospitals in Taiwan.

METHODS

Nasal swabs were obtained prospectively from 204 patients visiting the emergency department (ED) and 326 HCWs in two regional hospitals in Changhua, Taiwan, between February 2015 and June 2015. All the MRSA isolates were further molecularly characterized.

RESULTS

Of the 204 participating patients, the nasal carriage rates of S. aureus and MRSA were 22.1% and 7.8%, respectively. For HCWs, the S. aureus and MRSA carriage rates were 26.1% and 6.1%, respectively. There was no statistically significant difference in MRSA carriage rate between patients and HCWs (P = 0.447). Patients receiving hemodialysis were significantly associated with MRSA colonization (P = 0.012). The leading three sequence types (ST) were ST59 (16, 44.4%), ST45 (11, 30.6%), and ST239 (3, 8.3%) for all 36 MRSA isolates. ST59/SCCmec IV/t437/PVL-negative and ST45/SCCmec V/t1081/PVL-negative were the predominant clones among HCWs (30%) and participating patients (19%), respectively.

CONCLUSION

Overall, a substantial proportion of patients visiting the ED and HCWs harbored CA-MRSA, mostly ST59 strains, in their nares. It is noteworthy that MRSA ST45 strains supplanted ST239 as the second leading nasal MRSA colonization strain in our study.

Frequent MRSA nasal colonization among hospitalized children and their parents in Angola and São Tomé and Príncipe

BACKGROUND

The prevalence of nosocomial meticillin-resistant Staphylococcus aureus (MRSA) was previously estimated as 23% in a paediatric hospital in Luanda, Angola and 18% in a general hospital in São Tomé and Príncipe.

AIM

To evaluate the prevalence of S. aureus/MRSA colonization among hospitalized children and their parents at two hospitals in Angola and São Tomé and Príncipe.

METHODS

In 2017, 127 hospitalized children and 129 of their parents had nasal swabs for S. aureus/MRSA carriage in the two countries. The isolates were tested for the presence of the mecA and Panton-Valentine leukocidin (PVL) genes, and characterized by pulsed-field gel electrophoresis (PFGE), spa typing, multi-locus sequence typing and SCCmec typing.

FINDINGS

Twenty of 127 children (15.7%) and 13 of 129 parents (10.1%) were MRSA nasal carriers. Three lineages comprised 88% of the MRSA isolates: (i) PFGE A-ST5-SCCmec IVa (N=15; 45%), associated with spa type t105, recovered in Angola alone; (ii) PFGE N-ST8-IV/V (N=7; 21%), associated with spa types t008/t121, recovered in São Tomé and Príncipe alone; and (iii) PFGE B-ST88-IVa (N=7; 21%), associated with spa types t325/t786, present in both countries. Fifteen child/guardian pairs were colonized with identical MRSA (N=8) or meticillin-susceptible S. aureus (N=7) strains. PVL was detected in 25% of isolates, including two MRSA (ST30-V and ST8-IVa).

CONCLUSION

Hospitalized children and their parents are important reservoirs of MRSA. Infection control measures should focus on parents in order to minimize the spread of MRSA to the community.

Molecular epidemiology and virulence characteristics of Staphylococcus aureus nasal colonization in medical laboratory staff: comparison between microbiological and non-microbiological laboratories

Background

Medical laboratory staff are a high-risk population for colonization of Staphylococcus aureus (S. aureus) due to direct and dense contact with the pathogens; however, there is limited information about this colonization. This study sought to determine the prevalence and molecular characteristics of nasal colonization by S. aureus in medical laboratory staff in Guangzhou, southern China, and to compare the differences between microbiological laboratory (MLS) and non-microbiological laboratory (NMLS) staff.

Methods

S. aureus colonization was assessed by nasal swab cultures from 434 subjects, including 130 MLSs and 304 NMLSs from 33 hospitals in Guangzhou. All S. aureus isolates underwent the antimicrobial susceptibility test, virulence gene detection and molecular typing.

Results

The overall prevalence of S. aureus carriage was 20.1% (87/434), which was higher in MLSs than in NMLSs (26.2% vs. 17.4%, P < 0.05), while the prevalence of Methicillin-resistant S. aureus (MRSA) was similar. Living with hospital staff was associated with S. aureus carriage. The majority of the isolates harboured various virulence genes, and those in MLSs appeared less resistant to antibiotics and more virulent than their counterparts. A total of 37 different spa types were detected; among these, t338, t437, t189 and t701 were the most frequently encountered types. T338 was the main spa type contributing to nasal colonization Methicillin-sensitive S. aureus (MSSA) (13.0%), and t437-SCCmec IV was predominant in MRSA isolates (40%).

Conclusions

These findings provide insight into the risk factors, molecular epidemiology and virulence gene profiles of S. aureus nasal carriage among the medical laboratory staff in Guangzhou.

Electronic supplementary material

The online version of this article (10.1186/s12879-018-3024-x) contains supplementary material, which is available to authorized users.

Prevalence of Staphylococcus spp. nasal colonization among doctors of podiatric medicine and associated risk factors in Spain

Background

This study aimed to estimate the prevalence of methicillin-susceptible and -resistant Staphylococcus aureus (MSSA and MRSA) and methicillin-resistant Staphylococcus epidermidis (MRSE) nasopharyngeal carriage among Doctors of Podiatric Medicine (Podiatrists) and to determine the potential risk factors.

Methods

A cross-sectional study was carried out in 2016-2017 among 239 podiatrists in Spain. The presence of MSSA, MRSA, and MRSE was determined by microbiological analysis of nasal exudate and antimicrobial susceptibility was determined. Each podiatrist completed a questionnaire. The questionnaire comprised various parameters such as sex, age, podiatry experience duration, underlying diseases, prior antibiotic treatment, hospitalization during the last year, and use of a protective mask, an aspiration system, or gloves.

Results

The prevalence of MSSA, MRSA, and MRSE was 23.0%, 1.3%, and 23.8%, respectively. The MSSA prevalence was higher among podiatrists who did not use an aspiration system (32.3%) compared to those who did (19.3%; p = 0.0305), and among podiatrists with respiratory diseases (36.8%) compared to those without (20.8%; p = 0.0272). The MRSE prevalence was higher among men (33.7%) compared to women (8.6%; p = 0.0089), podiatrists aged ≥50 (38.5%) compared to ≤35 (17.8%; p = 0.0101), and podiatrists with ≥15 (39.3%) compared to ≤5 years of podiatry experience (12.5%; p = 0.0015). Among the S. aureus strains, 84.5% were resistant to penicillin, 22.4% to erythromycin, 20.7% to clindamycin, and 12.7% to mupirocin. The MRSE strains were resistant to penicillin (93.0%), erythromycin (78.9%), and mupirocin (73.7%).

Conclusions

The prevalence of S. aureus and S. epidermidis nasal carriage is low among Spanish podiatrists compared to other health professionals.

Can preoperative nasal cultures of Staphylococcus aureus predict infectious complications or outcomes following repair of fracture nonunion?

INTRODUCTION

Much has been studied with reference to methicillin resistant Staphylococcus aureus (MRSA) and methicillin sensitive S. aureus (MSSA) colonization and associated outcomes and comorbidities. In the area of Orthopedic surgery, literature predominantly comes from the field of arthroplasty. Little is known about outcomes of fracture and Orthopedic trauma patients in the setting of S. aureus colonization. We believe that MRSA/MSSA colonization in and of itself may be a weak marker for generally poor protoplasm, potentially with complex medical history including previous hospitalization or rehab placement. This milieu of risk factors may or may not contribute to poorer outcomes after fracture and fracture nonunion surgery. The purpose of this study is to determine if nasal swabbing for S. aureus (MRSA or MSSA) carriage can predict operative culture, complications, or outcomes following fracture nonunion surgery.

METHODS

Sixty-two consecutive patients undergoing surgery for fracture nonunion were prospectively followed. Data analyses were performed using grouped MRSA and MSSA carriers (Staphylococcus carriers: SC). Outcomes analyzed included time to healing, need for additional surgery, and persistent nonunion.

RESULTS

Twenty-six percent of patients (16/62) were identified as MSSA carriers, an additional 6.5% (4/62) carried MRSA. Follow-up of at least 12-months was obtained on 90% (56/62) of patients. White blood cell counts, erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP) values did not differ between SCs and non-carriers pre-operatively. Carriers were just as likely as non-carriers to culture positively for any pathogen at the time of surgery. Although SC's were three times as likely as non-carriers to grow S. aureus (15% vs. 5%), this difference did not reach statistical significance (p=0.3). Post-operative wound complications, antibiotic use, pain at follow-up and progression to healing did not differ between groups.

CONCLUSIONS

Ultimately, pre-operative nasal swabbing for S. aureus is a simple and non-invasive diagnostic tool with prognostic implications in patients undergoing fracture nonunion surgery. This study found that MRSA and MSSA colonized patients with fracture nonunion of long bones do not have an increased association with positive cultures or a predisposition towards greater post-operative infectious complications.

Staphylococcus Aureus Carriage in French Athletes at Risk of CA-MRSA Infection: a Prospective, Cross-sectional Study

Background

Staphylococcus aureus (SA) is a leading cause of infectious diseases in sports teams. In recent decades, community-associated SA (CA-SA) strains have emerged worldwide and have been responsible for outbreaks in sports teams. There are very few data on the prevalence of these strains in France, and none on the carriage among athletes.

Methods

We conducted a cross-sectional study to determine the SA carriage proportion among athletes practicing sports at risk for CA-SA infection in a French county, and determined the methicillin-resistant and/or CA-SA proportion. We also analyzed SA carriage according to risks factors and studied the SA clonality in a sample of our population.

Results

We included 300 athletes; SA carriage proportion was 61% (n = 183) and one was MRSA carrier (0.33%). The MRSA strain belonged to the clonal complex ST5. None of the strain produced Panton Valentine Leucocidin, and we did not find clonal distribution within the teams. Interestingly, we found a high throat-only carriage (n = 57), 31.1% of the SA carriers.

Conclusion

We found a high SA carriage with a local epidemiology quite different than that reported in a similar population in the USA. Further studies on SA carriage should include throat sampling.

Trial registration

The approved protocol was registered on ClinicalTrial.gov, NCT01148485.

Combining Two Methods of Global Sensitivity Analysis to Investigate MRSA Nasal Carriage Model

We apply two different sensitivity techniques to a model of bacterial colonization of the anterior nares to better understand the dynamics of Staphylococcus aureus nasal carriage. Specifically, we use partial rank correlation coefficients to investigate sensitivity as a function of time and identify a reduced model with fewer than half of the parameters of the full model. The reduced model is used for the calculation of Sobol' indices to identify interacting parameters by their additional effects indices. Additionally, we found that the model captures an interesting characteristic of the biological phenomenon related to the initial population size of the infection; only two parameters had any significant additional effects, and these parameters have biological evidence suggesting they are connected but not yet completely understood. Sensitivity is often applied to elucidate model robustness, but we show that combining sensitivity measures can lead to synergistic insight into both model and biological structures.

[Antibiotic susceptibility of Staphylococcus aureus and Streptococcus pneumoniae in healthy carrier individuals in primary care in Barcelona area]

Introducción

La información existente sobre la resistencia a los antibióticos se basa habitualmente en muestras de personas hospitalizadas. El objetivo fue evaluar la prevalencia de resistencia antibiótica de cepas de Staphylococcus aureus y Streptococcus pneumoniae de personas portadores nasales atendidas en las consultas de atención primaria según edad y sexo.

Diseño

Estudio transversal.

Emplazamiento

Siete centros de salud del área de Barcelona.

Participantes

Personas portadoras nasales a partir de 4 años de edad, sin signos de enfermedad infecciosa y que no habían tomado antibióticos ni habían estado hospitalizados en los 3 meses anteriores.

Mediciones principales

Se recogieron 3.969 frotis nasales válidos para identificación entre 2010 y 2011 y fueron enviados a un laboratorio central de microbiología para el aislamiento de ambos gérmenes. La resistencia a los antibióticos se estableció según los puntos de corte actuales de la guía del European Committee on Antimicrobial Susceptibility Testing.

Resultados

La prevalencia de S. aureus resistente a meticilina fue del 1,3% (IC 95%: 0,5-2,1%), con porcentajes de resistencia frente a fenoximetilpenicilina del 87,1% y a azitromicina del 11,6%, sin observar diferencias significativas según edad y sexo. Un 2,4% (IC 95%: 0,1-4,7%) de las cepas de neumococo fueron altamente resistentes a fenoximetilpenicilina y macrólidos, mientras que las mayores resistencias se observaron frente a cefaclor (53,3%), tetraciclina (20%) y cefuroxima (12,1%).

Conclusiones

Estos patógenos tienen resistencias más bajas en la comunidad que las que se observan en el medio hospitalario. Es importante que se conozca la resistencia antibiótica actual para poder hacer un uso más prudente de los antibióticos.

Factors associated with Staphylococcus aureus nasal carriage and molecular characteristics among the general population at a Medical College Campus in Guangzhou, South China

BACKGROUND

The nasal cavity is the main colonization site of Staphylococcus aureus (S. aureus) in human body. Nasal carriage may be a strong risk factor for some serious infection. There was still limited information about the nasal carriage for S. aureus in south China.

METHODS

Sought to determine the prevalence and molecular characteristics of S. aureus nasal carriage, 295 volunteers residing on a medicine campus were investigated and sampled the nasal cavity swab. Selected S. aureus isolates were carried through molecular analysis, including pulsed-field gel electrophoresis (PFGE), multilocus sequence analysis, staphylococcal cassette chromosome mec (SCCmec) and virulence gene detection.

RESULTS

A total of 73 S. aureus isolates were recovered from separate subjects (24.7%, 73/295), with one methicillin-resistant S. aureus (MRSA) isolate (0.3%, 1/295). Among the 73 isolates, 71 isolates were successfully grouped into 13 pulsotypes by PFGE analysis, with profiles A and L the most prevalent; 12 sequence types (STs) were found among the 23 isolates which had similar drug resistant spectrum. ST59, ST188 and ST1 were the most prevalent, accounting for 17.4, 13.0 and 13.0% of all isolates, respectively. The MRSA isolate presented ST8-SCCmec III. 56.5% of isolates carried both the staphylococcal enterotoxin A (sea) and enterotoxin B (seb) genes. 83.6% of the S. aureus isolates were resistant to penicillin, all isolates were susceptible to quinupristin/dalfopristin, levofloxacin, teicoplanin and vancomycin. The most common risk factors for S. aureus carriage were being male, age ≤30 years, and nasal cavity cleaning habits.

CONCLUSIONS

Colonization by S. aureus was greater among male and young age (20-30 years) students and those with irregularity nasal cleaning. The S. aureus isolates selected were revealed into various sequence types and pulsotypes, indicating molecular heterogeneity among S. aureus isolates from the populations in the medical college in Guangzhou.

Upper airway viruses and bacteria in urban Aboriginal and Torres Strait Islander children in Brisbane, Australia: a cross-sectional study

BACKGROUND

Respiratory morbidity in Australian Indigenous children is higher than their non-Indigenous counterparts, irrespective of urban or remote residence. There are limited studies addressing acute respiratory illness (ARI) in urban Indigenous children, particularly those that address the upper airway microbiome and its relationship to disease. We aimed to describe the prevalence of upper airway viruses and bacteria in symptomatic and asymptomatic urban-based Australian Indigenous children aged less than 5 years.

METHODS

A cross-sectional analysis of data collected at baseline in an ongoing prospective cohort study of urban Aboriginal and Torres Strait Islander children registered with a primary health care service in the northern suburbs of Brisbane, Australia. Clinical, demographic and epidemiological data and bilateral anterior nasal swabs were collected on enrolment. Polymerase chain reaction was performed on nasal swabs to detect 17 respiratory viruses and 7 bacteria. The primary outcome was the prevalence of these microbes at enrolment. Logistic regression was performed to investigate differences in microbe prevalence between children with and without acute respiratory illness with cough as a symptom (ARIwC) at time of specimen collection.

RESULTS

Between February 2013 and October 2015, 164 children were enrolled. The median age at enrolment was 18.0 months (IQR 7.2-34.3), 49.4% were boys and 56 children (34.2%) had ARIwC. Overall, 133/164 (81%) nasal swabs were positive for at least one organism; 131 (79.9%) for any bacteria, 59 (36.2%) for any virus and 57 (34.8%) for both viruses and bacteria. Co-detection of viruses and bacteria was more common in females than males (61.4% vs 38.6%, p = 0.044). No microbes, alone or in combination, were significantly associated with the presence of ARIwC.

CONCLUSIONS

The prevalence of upper airways microbes in asymptomatic children is similar to non-Indigenous children with ARIwC from the same region. Determining the aetiology of ARIwC in this community is complicated by the high prevalence of multiple respiratory pathogens in the upper airways.

STUDY REGISTRATION

Australia New Zealand Clinical Trial Registry Registration Number: 12,614,001,214,628. Retrospectively registered.

Staphylococcus aureus nasal carriage in health care workers: First report from a major public hospital in Argentina

Staphylococcus aureus causes numerous mild to severe infections in humans, both in health facilities and in the community. Patients and health care workers (HCWs) may disseminate strains during regular medical examinations or hospitalization. The aim of this study was to determine the nasal carriage rate of methicillin-susceptible and methicillin-resistant S. aureus among health care workers at Hospital Provincial del Centenario, a public general hospital in Rosario, Argentina. A transversal study was conducted on 320 health care workers. Nasal swabs were taken and presumptive S. aureus colonies were isolated. Bacterial identity and methicillin resistance status were confirmed by amplification of the nuc and mec genes. Chi square test and Fisher exact test were used for statistical analysis. Of 320 HCWs, 96 (30%) were nasal carriers of S. aureus, 20 of whom (6.3%) carried methicillin-resistant S. aureus (MRSA) and 76 (23.7%) methicillin-susceptible S. aureus (MSSA). Carriage was within thepublished values for physicians (30%) and higher for technicians (57%). Accompanying resistance (62/96, 64.6%) was detected, including resistance to fluoroquinolones (23/96, 24%), aminoglucosides (13/96, 13.5%) or to macrolides (33/96, 34.4%). All the strains were susceptible to vancomycin whereas only 3.1% (3/96), all of them on MSSA strains, were resistant to mupirocin. This study is the first one of its kind in Argentina and one of the few performed in South America, to highlight the relevance of nasal carriage of MRSA and MSSA in health care personnel and brings to light the need for consensus recommendations for regular S. aureus carriage screening as well as for decolonization strategies.

Antimicrobial Resistance and Molecular Characteristics of Nasal Staphylococcus aureus Isolates From Newly Admitted Inpatients

Staphylococcus aureus, or methicillin-resistant S. aureus (MRSA), is a significant pathogen in both nosocomial and community infections. Community-associated MRSA (CA-MRSA) strains tend to be multi-drug resistant and to invade hospital settings. This study aimed to assess the antimicrobial resistance and molecular characteristicsof nasal S. aureus among newlyadmitted inpatients.In the present study, 66 S. aureus isolates, including 10 healthcare-associated MRSA (HA-MRSA), 8 CA-MRSA, and 48 methicillin-sensitive S. aureus (MSSA) strains, were found in the nasal cavities of 62 patients by screening 292 newlyadmitted patients. Antimicrobial resistance and molecular characteristics of these isolates, including spa-type, sequence type (ST) and SCCmec type, were investigated. All isolates were sensitive to linezolid, teicoplanin, and quinupristin/dalfopristin, but high levels of resistance to penicillin and erythromycin were detected. According to D-test and erm gene detection results, the cMLS_B and iMLS_B phenotypes were detected in 24 and 16 isolates, respectively. All 10 HA-MRSA strains displayed the cMLS_B phenotypemediated by ermA or ermA/ermC, while the cMLS_B CA-MRSA and MSSA strains carried the ermB gene. Molecular characterization revealedall 10 HA-MRSA strains were derived from the ST239-SCCmec III clone, and four out of eight CA-MRSA strains were t437-ST59-SCCmec V. The results suggest that patients play an indispensable role in transmitting epidemic CA-MRSA and HA-MRSA strains.

Nasal carriage of methicillin resistant Staphylococcus aureus among health care workers at Al Shifa hospital in Gaza Strip

Background

Nasal carriage of Staphylococcus aureus among hospital personnel is a common cause of hospital acquired infections. Emergence of drug resistant strains especially methicillin resistant S. aureus (MRSA) is a serious problem in hospital environment. Therefore, the aim of this study was to determine the nasal carriage rate of S. aureus and MRSA among Health Care Workers (HCWs) at Al Shifa Hospital, the major hospital in Gaza Strip.

Methods

A cross sectional study was conducted on 200 HCWs. Nasal swabs were collected during February — April 2015, and cultured on blood and mannitol salt agar. The isolates were identified as S. aureus based on morphology, coagulase test, DNase test and mannitol salt agar fermentation. Disk diffusion antibiotic susceptibility tests were performed according to the guidelines of the Clinical and Laboratory Standards Institute. MRSA were confirmed by detection of the mecA gene by PCR.

Results

Out of the 200 healthcare workers, 62 (31%) carried S. aureus, of which 51 (82.3%) were MRSA. Therefore, 25.5% of all HCWs were identified as MRSA carriers. MRSA carriage rate was highest among nurses (30.4%) whereas the carriage rate among doctors was (16%). The majority of MRSA carriers were workers of internal medicine department and surgical wards (41.3 and 35% respectively). Out of the 51 MRSA isolates identified by oxacillin disc resistance, 40 were confirmed by PCR targeting the mecA gene. Penicillin showed the highest rate of resistance among MRSA and MSSA isolates (100%).

Conclusions

The high rate of nasal MRSA carriage among healthcare workers found in this study is alarming and highlights the need for adjusted infection control measures to prevent MRSA transmission from HCWs to the vulnerable patient.

Whole genome SNP typing to investigate methicillin-resistant Staphylococcus aureus carriage in a health-care provider as the source of multiple surgical site infections

BACKGROUND

Prevention of nosocomial transmission of infections is a central responsibility in the healthcare environment, and accurate identification of transmission events presents the first challenge. Phylogenetic analysis based on whole genome sequencing provides a high-resolution approach for accurately relating isolates to one another, allowing precise identification or exclusion of transmission events and sources for nearly all cases. We sequenced 24 methicillin-resistant Staphylococcus aureus (MRSA) genomes to retrospectively investigate a suspected point source of three surgical site infections (SSIs) that occurred over a one-year period. The source of transmission was believed to be a surgical team member colonized with MRSA, involved in all surgeries preceding the SSI cases, who was subsequently decolonized. Genetic relatedness among isolates was determined using whole genome single nucleotide polymorphism (SNP) data.

RESULTS

Whole genome SNP typing (WGST) revealed 283 informative SNPs between the surgical team member's isolate and the closest SSI isolate. The second isolate was 286 and the third was thousands of SNPs different, indicating the nasal carriage strain from the surgical team member was not the source of the SSIs. Given the mutation rates estimated for S. aureus, none of the SSI isolates share a common ancestor within the past 16 years, further discounting any common point source for these infections. The decolonization procedures and resources spent on the point source infection control could have been prevented if WGST was performed at the time of the suspected transmission, instead of retrospectively.

CONCLUSIONS

Whole genome sequence analysis is an ideal method to exclude isolates involved in transmission events and nosocomial outbreaks, and coupling this method with epidemiological data can determine if a transmission event occurred. These methods promise to direct infection control resources more appropriately.

Genomic diversity and antimicrobial susceptibility profiling of nasal carriage Staphylococcus aureus isolated from pediatric ward in Western Iran

Nasal carriage of Staphylococcus aureus (S. aureus) probably causes the transmission of infection between individuals in hospital and community. This study aimed to evaluate the molecular epidemiology and antibiotic resistance pattern of nasal carriage S. aureus in pediatric ward patients and personnel. A total of 122 Nasal samples were taken from 28 personnel and 94 hospitalized patients in the pediatric ward. Minimum Inhibitory Concentration (MIC) to vancomycin and cefoxitin was determined by Agar dilution method strips. All S. aureus isolates were analyzed by pulsed-field gel electrophoresis (PFGE). A total of 41 S. aureus were isolated from the patients. 16 isolates (39.09%) were hospital-associated S. aureus (HA-SA) and 25 (60.97%) were community-associated S. aureus (CA-SA); also, 13 S. aureus isolates were obtained from the personnel. Based on MIC results, all of S. aureus isolates were susceptible to vancomycin, and in 41 patient isolates, 13 isolates (31.7%) were resistant to cefoxitin (MRSA). Of 13 S. aureus isolates of the personnel, 3 (23%) isolates were MRSA. Totally 11 common clones and 13 single clones were obtained. In conclusion the prevalence of CA-SA in the ward was higher than that of HA-SA. In the strains obtained from a hospital ward, there was a high epidemiology, genotypic diversity in the studied ward. However, horizontal transfer of S. aureus was observed between patients and between personnel and patients, which indicated the risk of transmission of resistant strains in the hospital wards.

Link between nasal carriage of Staphylococcus aureus and infected diabetic foot ulcers

AIMS

Nasal carriage of Staphylococcus aureus in diabetic patients may be a risk factor for diabetic foot lesion infections. The aims of this study were to compare the genotypic profiles of S. aureus strains isolated from nares and diabetic foot ulcers (DFUs) using microarray technology.

METHODS

Patients were included if they were admitted for diabetic foot infection (DFI) at any of three diabetology departments of Montpellier and Nîmes University Hospitals between 1 September 2010 to 30 June 2012. All S. aureus isolates were analyzed using oligonucleotides arrays; S. aureus resistance and virulence genes were determined and each isolate was affiliated to a clonal complex.

RESULTS

The prevalence of S. aureus nasal carriage among the 276 included patients was 39.5% (n=109), while 36.6% (n=101) had S. aureus at both sites (nares and foot wounds) and, of these patients, 65.3% of patients harboured the same strain at both sites. In addition, the spread of the methicillin-resistant S. aureus (MRSA) ST398 clone in DFI and its tropism for bone were also further confirmed.

CONCLUSION

These findings appear to provide new arguments in favour of the systematic detection of nasal S. aureus carriage to anticipate the management of DFI.

Nasal carriage of common bacterial pathogens among healthy kindergarten children in Chaoshan region, southern China: a cross-sectional study

BACKGROUND

Nasal colonization with bacterial pathogens is associated with risk of invasive respiratory tract infections, but the related information for Chinese healthy children is scarce.

METHODS

This cross-sectional study was conducted with healthy children from 6 kindergartens in the Chaoshan region, southern China during 2011-2012. Nasal swabs were examined for five common bacterial pathogens: Streptococcus pneumoniae, Haemophilus influenzae, Haemophilus parainfluenzae, Moraxella catarrhalis, and Staphylococcus aureus.

RESULTS

Among 1,088 children enrolled, 79.6 % (866) were target-bacterial carriers, of which 34.4 % (298/866) were positive for ≥2 bacteria species. The most common pathogen in the bacterial carriers was M. catarrhalis (76.6 %), followed by S. pneumoniae (26.6 %), S. aureus (21.8 %), H. parainfluenzae (12.7 %), and H. influenzae (2.3 %). Multiple logistic regression analyses showed negative associations between age and the overall or multiple bacterial carriage, and between the father's education level and multiple bacterial carriage (all p < 0.05). Age was negatively associated with the carriage of M. catarrhalis and S. pneumoniae, and positively associated with the S. aureus carriage (all p < 0.0001).

CONCLUSIONS

This study shows high nasal carriage of common pathogenic bacteria and coexistence of multiple pathogens in healthy Chaoshan kindergarten children, with M. catarrhalis as the commonest colonizer. Increasing age of children and higher paternal education are associated with lower risk of bacterial carriage. Longitudinal follow-up studies would be helpful for better understanding the infection risk in bacterial pathogen carriers.

Molecular characterization of Staphylococcus aureus from nasal samples of healthy farm animals and pets in Tunisia

A total of 261 healthy farm and pet animals (75 cattle, 52 goats, 100 dogs, and 34 cats) from different regions of Tunisia were screened for Staphylococcus aureus nasal carriage. Molecular typing of isolates (by spa- and multilocus sequence-typing) was performed, and their antimicrobial resistance and virulence genotypes were determined by PCR and sequencing. S. aureus isolates were detected in 17 of 261 tested samples (6.5%). All S. aureus isolates recovered were methicillin-susceptible (MSSA), and one isolate/sample was further studied. Eight different spa types were detected (t189, t279, t582, t701, t1166, t1268, t1534, and t1773), and eight different sequence types were identified (ST6, ST15, ST45, ST133, ST188, ST700 [clonal complex CC130], ST2057, and a new ST2121). MSSA from pets (six isolates) showed resistance to (number of isolates, resistance gene): penicillin (six, blaZ), tetracycline (one, tet[M]), erythromycin one, erm[A]), streptomycin (one, ant[6]-Ia), and ciprofloxacin (one). All isolates from farm animals showed susceptibility to the tested antimicrobials, except for two penicillin-resistant isolates. Five S. aureus isolates from goats and cats harbored the lukF/lukS-PV genes, encoding the Panton-Valentine leukocidin, and six isolates from goats harbored the tst virulence gene. In addition, diverse combinations of enterotoxin genes were detected, including two variants of the egc cluster. Goats and cats could represent a reservoir of important toxin genes, with potential implications in animal and human health.

Nasal Carriage of Uncommon Coagulase-Negative Staphylococci in Nurses and Physicians of Tehran University Hospitals

Coagulase-negative staphylococci (CoNS) have been identified as a major cause of nosocomial infections. Nasal carriage of CoNS in nurses and physicians is known to be an important risk factor for potential hospital infections. This study was carried out to investigate the prevalence of nasal carriage of uncommon coagulase-negative staphylococci among nurse and physician staffs of Tehran University Hospitals. A total of 116 CoNS were isolated from anterior nares of the study participants working in different wards of the hospitals. Thirteen uncommon CoNS were identified using phenotypic and biochemical methods, were subsequently confirmed by API kits. Staphylococcus xylosus, Staphylococcus haemolyticus, and Staphylococcus capitis species accounted for 53.85%, 30.77%, and 15.38% from the isolates, respectively. Six isolates (46.15%) were found to be resistant to methicillin. In conclusion, screening of healthcare workers for uncommon CoNS colonization along with identification and testing for susceptibility of cultured isolates is of paramount importance in strengthening effective nosocomial infection control and prevention measures.

[Survey among French dialysis practitioners about the screening and decolonization of nasal Staphylococcus aureus carriage in dialysis patients]

Staphylococcus aureus nasal carriage is frequent in dialysis patients and is associated with an increased risk of staphylococcal infections in this population. Data from the literature showed that decolonization of S. aureus nasal carriers in hemodialysis and peritoneal dialysis reduce S. aureus catheter-related infections. During the last national congress of nephrology, a survey was conducted among volunteer dialysis physicians to evaluate their practice about screening and decolonization of S. aureus nasal carriage among their patients. Only 30 participants (45.5% [30/66]) declared to screen S. aureus nasal carriage in patients of hemodialysis and 59.6% (31/52) in peritoneal dialysis. Participants declared to decolonize their patients before insertion of a vascular catheter in 55.8% of cases. This small study would need to be completed by a national survey.

Differential induction of innate defense antimicrobial peptides in primary nasal epithelial cells upon stimulation with inflammatory cytokines, Th17 cytokines or bacterial conditioned medium from Staphylococcus aureus isolates

To date it is incompletely understood why half of the human population is intrinsically resistant to Staphylococcus aureus colonization whereas the other half is intermittently or permanently colonized. Nasal colonization represents the primary niche for S. aureus. We therefore investigated whether primary nasal epithelial cells (HNEC) express antimicrobial peptides (AMPs) upon stimulation by inflammatory cytokines or bacterial conditioned medium (BCM) of different colonizing and invasive staphylococci. Stimulation with classical cytokines (IL-1β, TNF-α, IFN-γ) potently induced hBD-3 and RNase7 in HNEC. Th17 cytokines (IL-17A, IL-17F, IL-22) yielded comparably weak hBD-3 and RNase7 induction and no synergistic effects with classical cytokines. BCM of S. aureus and Staphylococcus epidermidis isolates moderately induced hBD3 and RNase7 mRNA expression without significant differences when comparing colonizing vs. invasive isolates. Our results indicate that HNEC contribute to the innate defense by secretion of an AMP-containing chemical defense shield along the nasal mucosa i.e. within the primary colonization niche of S. aureus. Further studies are needed to investigate whether a deficient AMP expression in the nasal mucosa may be related to different S. aureus carrier states. AMPs or AMP-inducing agents may be promising candidates for future topical decolonization regimens that aim to prevent invasive S. aureus infections.

Prevalence and risk factors of Staphylococcus spp. carriage among dogs and their owners: A cross-sectional study

This study investigated colonization and association of staphylococci between healthy dogs and their owners. In a cross-sectional study, nasal carriage and antibiotic susceptibility of isolated staphylococci were determined for 119 dogs and 107 owners. Relatedness of the Staphylococcus isolates in dogs and their owners was investigated using antibiograms, toxin profiles, and genotyping by pulsed-field gel electrophoresis (PFGE), multilocus sequence type, and spa typing. Risk factors for carriage of methicillin-resistant staphylococci in dogs were also evaluated. Staphylococcus spp. were isolated from 65 (60.7%) owners and 44 (37.0%) dogs. The following species were isolated, listed in order of decreasing frequency: S. epidermidis, S. pseudintermedius, S. aureus, S. scheiferi subsp. coagulans, S. haemolyticus, S. sciuri, S. saprophyticus and S. warneri. S. pseudintermedius (65.9%) was the major isolate in dogs while S. epidermidis (81.5%) was the major type in owners. Among the isolates, 71.6% were methicillin resistant (MR) and 95.4% of the isolates demonstrated multi-drug resistance regardless of the origin. Only one dog-owner pair shared the same Staphylococcus spp. (S. pseudintermedius); however, the organisms were of different PFGE subtypes and exhibited different antibiotic resistance and toxin profiles while both isolates displayed same sequence type (ST365). While the dog-origin isolate showed spa type t02, the owner-origin isolate was negative to PCRs targeting spa gene sequence. Risk factor analysis showed that the presence of cohabitant animals was correlated with the nasal carriage of MR staphylococci in dogs. The cumulative data indicated that animal- and owner-origin staphylococci have various subtypes with high prevalence of MR; however, the bacteria are not shared between healthy dogs and their owners.

Prevalence, risk factors and sequelae of Staphylococcus aureus carriage in diabetes: the Fremantle Diabetes Study Phase II

AIMS

To determine the prevalence and associates of Staphylococcus aureus and methicillin-resistant S. aureus (MRSA) carriage in community-based diabetes, and their relationship to hospitalization with S. aureus infection.

METHODS

A cross-sectional subset of 660 Fremantle Diabetes Study Phase II patients (mean±SD age 65.1±11.5years, 53.1% males) had nasal/axillary swabs as part of biennial review. Serum 25-hydroxyvitamin D (25(OH)D) concentrations were measured in 358 patients. Those with positive swabs were invited back for a repeat swab. Hospitalizations with S. aureus infections were ascertained from validated data linkage. Multiple logistic regression was used to identify associates of carriage, and Cox proportional hazards modelling was used to determine predictors of subsequent hospitalization.

RESULTS

258 patients (39.1%) were positive for S. aureus and eight (3.1%) carried MRSA. S. aureus carriage was independently associated with being married/in a de facto relationship and inversely with older age and being born overseas (P≤0.043). Repeat swabs in 137 patients (53.1% of those with an initially positive swab) grew S. aureus in 113 (82.5%). Five of eight MRSA-positive patients were re-swabbed, and four were MRSA-positive. Independent predictors of hospitalization with staphylococcal infection after the initial swab were S. aureus carriage (hazard ratio (95% CI) 5.42 (1.49-19.79)), prior hospitalization with S. aureus (4.84 (1.19-19.63)) and Aboriginality (7.20 (1.91-27.17) (P≤0.027). Serum 25(OH)D was not associated with S. aureus carriage or subsequent hospitalization.

CONCLUSIONS

S. aureus and MRSA carriage in our patients was consistent with previous general population studies. There were no diabetes-specific risk factors. Persistent colonization may underlie the increased risk of hospitalization with S. aureus.

Nasal carriage of methicillin resistant Staphylococcus aureus among health care workers at a tertiary care hospital in Western Nepal

BACKGROUND

Staphylococcus aureus is a frequent cause of infections in both the community and hospital. Methicillin-resistant Staphylococcus aureus continues to be an important nosocomial pathogen and infections are often difficult to manage due to its resistance to multiple antibiotics. Healthcare workers are important source of nosocomial transmission of MRSA. This study aimed to determine the nasal carriage rate of S. aureus and MRSA among healthcare workers at Universal College of Medical Sciences and Teaching Hospital, Nepal and to determine antibiotic susceptibility pattern of the isolates.

METHODS

A cross-sectional study involving 204 healthcare workers was conducted. Nasal swabs were collected and cultured on Mannitol salt agar. Mannitol fermenting colonies which were gram positive cocci, catalase positive and coagulase positive were identified as S. aureus. Antibiotic susceptibility test was performed by modified Kirby-Bauer disc diffusion method. Methicillin resistance was detected using cefoxitin disc diffusion method.

RESULTS

Of 204 healthcare workers, 32 (15.7 %) were nasal carriers of S. aureus and among them 7 (21.9 %) were carrier of MRSA. Overall nasal carriage rate of MRSA was 3.4 % (7/204). Highest MRSA nasal carriage rate of 7.8 % (4/51) was found among nurses. Healthcare workers of both surgical wards and operating room accounted for 28.6 % (2/7) of MRSA carriers each. Among MRSA isolates inducible clindamycin resistance was observed in 66.7 % (2/3) of erythromycin resistant isolates.

CONCLUSIONS

High nasal carriage of S. aureus and MRSA among healthcare workers (especially in surgery ward and operating room) necessitates improved infection control measures to be employed to control MRSA transmission in our setting.

Mathematical Model for MRSA Nasal Carriage

An interesting biological phenomenon that is a factor for the spread of antibiotic-resistant strains, such as MRSA, is human nasal carriage. Here, we evaluate several biological hypotheses for this problem in an effort to better understand and narrow the scope of the dominant factors that allow these bacteria to persist in otherwise healthy individuals. First, we set up and analyze a simple PDE model created to generally mimic the interactions of the microbes and nasal immune response. This includes looking at different types of diffusion and chemotaxis terms as well as different boundary conditions. Then, using sensitivity analysis, we walk through several biological hypotheses and compare to the model's results looking for persistent infection scenarios indicated by the model's bacteria component surviving over time.

Prevalence of nasal carriage of methicillin-resistant Staphylococcus aureus in children with diabetes mellitus: Trends between 2005 and 2013

The aim of this prospective study was to establish the methicillin-resistant Staphylococcus aureus (MRSA) colonization rates in pediatric outpatients with type 1 diabetes mellitus, while also evaluating changes in colonization rates over time. There was no significant difference between 2005 and 2013 patients in terms of demographic and clinical findings. MRSA colonization rates were 0.7% (in 101 patients) and 0.9% (in 134 patients) (P = .84). Although increased MRSA colonization has become a significant problem worldwide, it does not seem to be a major issue in our diabetic outpatient population.

Analysis of Antibiotic Resistance Genes and its Associated SCCmec Types among Nasal Carriage of Methicillin Resistant Coagulase Negative Staphylococci from Community Settings, Chennai, Southern India

OBJECTIVE

The study was designed to find the distribution of SCCmec types and the various antibiotic resistance genes amongst MR-CoNS isolates from asymptomatic individuals.

MATERIALS AND METHODS

A total of 145 nasal swabs were collected from asymptomatic healthy individuals from community settings. Identification and speciation of CoNS were done by standard biochemical methods. Screening of methicillin resistance (mecA gene) and detection of various antibiotic resistant genes were done using multiplex PCR method. SCCmec types (I - V) were determined using multiplex PCR.

RESULTS

50 (44.6%) isolates were found to be methicillin resistant both by cefoxitin method and multiplex PCR. S. epidermidis (40%) was the predominant species followed by S. haemolyticus (28%), S. hominis (20%) and S. warneri (12%). Highest resistance was shown for cotrimoxazole (26%), followed by ciprofloxacin (24%), tetracycline (20%), erythromycin (18%), fusidic acid (10%) and mupirocin (6%). Among SCCmec types, 44 isolates showed single type, including type I (30%), type IV (24%), type II (18%), type V (14%) and type III (2%). 6 isolates showed two types, III+IV (n= 2), II+V (n=2), IV+V (n=1) and type I+V (n=1).

CONCLUSION

In conclusion, to the best of our knowledge, this is the first study in India to study the distribution of antibiotic resistant genes and SCCmec types among MR-CoNS from community settings. This study highlights high prevalence of MR-CoNS in community and its role in harbouring genetically diverse SCCmec elements as antibiotic resistance determinant.

Staphylococcus Aureus carriage and long-term Rituximab treatment for Granulomatosis with polyangiitis

Objective. Chronic nasal carriage of Staphylococcus aureus (SA) increases the risk of relapse while Rituximab (RTX) is an effective agent for inducing and maintaining remission in patients with Granulomatosis with polyangiitis (GPA). We investigated whether B cell depletion and hypogammaglobulinemia that occur during RTX treatment increase the risk of chronic SA nasal carriage and subsequent disease flares, in GPA patients on long-term RTX maintenance therapy.

Methods. Retrospective cohort study from a disease registry involving 29 GPA patients receiving RTX maintenance (median RTX dose of 9 g) during a median period of 49 months. Nasal swabs were collected prior and during RTX for a median of 3 and 9 swabs respectively. Persistent SA nasal carriage was defined with the presence of SA in more than 75% of nasal swabs.

Results. SA nasal carriage did not change during RTX (p = 0.297). However, the rate of positive nasal swabs in GPA patients with transient SA nasal carriage during RTX maintenance increased from 0 prior RTX to 0.42 during RTX (p = 0.017). Persistent SA nasal carriage did not increase the risk of relapses (p = 0.844), of hypogammaglobulinemia (p = 0.122) and of severe infections (p = 0.144), but reduced the risk of chronic infections (p = 0.044). Change in SA carriage status during RTX did not influence the risk of relapses (p = 0.756), hypogammaglobulinamia (p = 0.474) and infections, either severe (p = 0.913) or chronic (p = 0.121).

Conclusion. Long-term RTX maintenance therapy in GPA patients did not significantly influence SA nasal carriage status. Persistent SA carriage during long-term RTX treatment did not seem to increase the risk of relapses, but seemed to decrease the risk of hypogammaglobulinemia associated chronic infections.