Outbreak of Panton-Valentine Leukocidin-Associated Methicillin-Susceptible Staphylococcus aureus Infection in a Rugby Team, France, 2010-2011

Staphylococcus aureus strains that produce Panton-Valentine leukocidin are known to cause community infections. We describe an outbreak of skin abscesses caused by Panton-Valentine leukocidin-producing methicillin-susceptible S. aureus (clonal complex 121) in a professional rugby team in France during July 2010-February 2011. Eight team members were carriers; 7 had skin abscesses.

Local circulating clones of Staphylococcus aureus in Ecuador

The spread of pandemic Staphylococcus aureus clones, mainly methicillin-resistant S. aureus (MRSA), must be kept under surveillance to assemble an accurate, local epidemiological analysis. In Ecuador, the prevalence of the USA300 Latin American variant clone (USA300-LV) is well known; however, there is little information about other circulating clones. The aim of this work was to identify the sequence types (ST) using a Multiple-Locus Variable number tandem repeat Analysis 14-locus genotyping approach. We analyzed 132 S. aureus strains that were recovered from 2005 to 2013 and isolated in several clinical settings in Quito, Ecuador. MRSA isolates composed 46.97% (62/132) of the study population. Within MRSA, 37 isolates were related to the USA300-LV clone (ST8-MRSA-IV, Panton-Valentine Leukocidin [PVL] +) and 10 were related to the Brazilian clone (ST239-MRSA-III, PVL−). Additionally, two isolates (ST5-MRSA-II, PVL−) were related to the New York/Japan clone. One isolate was related to the Pediatric clone (ST5-MRSA-IV, PVL−), one isolate (ST45-MRSA-II, PVL−) was related to the USA600 clone, and one (ST22-MRSA-IV, PVL−) was related to the epidemic UK-EMRSA-15 clone. Moreover, the most prevalent MSSA sequence types were ST8 (11 isolates), ST45 (8 isolates), ST30 (8 isolates), ST5 (7 isolates) and ST22 (6 isolates). Additionally, we found one isolate that was related to the livestock associated S. aureus clone ST398. We conclude that in addition to the high prevalence of clone LV-ST8-MRSA-IV, other epidemic clones are circulating in Quito, such as the Brazilian, Pediatric and New York/Japan clones. The USA600 and UK-EMRSA-15 clones, which were not previously described in Ecuador, were also found. Moreover, we found evidence of the presence of the livestock associated clone ST398 in a hospital environment.

Efficacy of ultraviolet C light at sublethal dose in combination with antistaphylococcal antibiotics to disinfect catheter biofilms of methicillin-susceptible and methicillin-resistant Staphylococcus aureus and Staphylococcus epidermidis in vitro

Background

Biofilm formation inside inserted medical devices leads to their failure and acts as a source of refractory infections. The ultraviolet C (UVC) light is a potential therapy that can be used against the biofilm of bacterial pathogens.

Objective

We evaluated the efficacy of sublethal dose of UVC light with anti-staphylococcal antibiotics against biofilms made from 30 isolates of methicillin-susceptible Staphylococcus aureus and methicillin-resistant S. aureus and S. epidermidis on vascular catheters.

Materials and methods

A novel biofilm device was used to assess the combined approach. The biofilms on the catheters were irradiated with the UVC light at 254 nm and irradiance of 6.4 mW followed by treatment with vancomycin or quinupristin/dalfopristin at twice their minimum bactericidal concentrations or with linezolid at 64 µg/mL for 24 hours. The catheters were cut into segments and sonicated, and the number of the sessile cells was determined colorimetrically using XTT viable cells assay. The effect of UVC radiation followed by treatment with an antistaphylococcal antibiotic on the viability of the bacteria in the biofilm was visualized using LIVE/DEAD BacLight bacterial viability stain and confocal laser scanning microscopy.

Results

Exposure of the bacterial biofilms to the UVC light or each of the antibiotics alone was ineffective in killing the bacteria. Treatment of the biofilms with the antibiotics following their exposure to UVC light significantly (P<0.001) reduced the number of viable cells within the biofilms but did not completely eradicate them.

Conclusion

To our knowledge, this combinatorial approach has not been investigated before. The combined approach can be used as a therapeutic modality for managing biofilm-associated infections by preventing the establishment of biofilms and/or disrupting the formed biofilms on the inserted medical devices with the goal of increasing their usefulness and preventing infectious complications. Further investigations are needed to assess the effectiveness of the combined approach in the clinical settings.

Prevalence and antimicrobial susceptibility pattern of methicillin resistant Staphylococcus aureus isolated from clinical samples at Yekatit 12 Hospital Medical College, Addis Ababa, Ethiopia

Background

Staphylococcus aureus particularly MRSA strains are one of the major causes of community and hospital acquired bacterial infections. They are also becoming increasingly multi-drug resistant and have recently developed resistance to vancomycin, which has been used successfully to treat MRSA for many years. In-vitro determination of drug resistance patterns of S. aureus is critical for the selection of effective drugs for the treatment of staphylococci infections.

The main aim of this study was to determine the prevalence of methicillin resistant S. aureus strains from different clinical specimens from patients referred for routine culture and sensitivity testing.

Method

A cross sectional study was conducted among 1360 participants at Yekatit 12 Hospital Medical College in Ethiopia from September 2013 to April 2014. Clinical samples from various anatomical sites of study participants were cultured on blood agar and mannitol salt agar and identified to be S. aureus by using catalase, coagulase and DNAse tests. S. aureus isolates then were screened for MRSA using 30 μg cefoxitin disc and other 11 antimicrobial drugs by disc diffusion procedure, and agar dilution and E tests for vancomycin. All S. aureus isolates examined for beta-lactamase production by employing nitrocefin. Data were analyzed using SPSS version 20 software and logistic regressions were applied to assess any association between dependent and independent variables.

Results

Of 1360 clinical specimens analyzed S. aureus was recovered from (194, 14.3 %). Rate of isolation of S. aureus with regard to clinical specimens was the highest in pus (118, 55.4 %).No S. aureus was isolated from CSF and urethral discharge. Out of 194 S. aureus isolates, (34, 17.5 %) were found out to be MRSA and the remaining (160, 82.5 %) were MSSA. Ninety eight (50.5 %) S. aureus were multi drug resistant and the highest isolates were resistant to penicillin (187, 96.4 %) and least resistant for clindamycin (23, 11.9 %) and vancomycin (10, 5.1 %). MRSA strains were 100 % resistant to penicillin G, erythromycin, trimethoprim-sulfamethoxazole and least resistant to vancomycin (10, 29.4 %). Out of 194 S. aureus isolates (153, 79.0 %) were beta-lactamase producers.

Conclusion

In this study S. aureus isolates exhibited very high degree of resistance to different antibiotics. The isolates were also multidrug resistant to several combinations of the tested antibiotics. The emergence of vancomycin resistant S. aureus highlights the value of prudent prescribing of antibiotics and avoiding their irrational use.

Staphylococcus aureus aortitis and retroperitoneal fibrosis: A case report and literature review

An infected aortic aneurysm is a process with high mortality rate. Survival is dependent on an early diagnosis and surgical management. This case report details a rare presentation of aortitis with persistent methicillin-sensitive Staphylococcus aureus (MSSA) bacteremia, which initially presented as retroperitoneal fibrosis and was ultimately fatal.

Molecular characterization of Staphylococcus aureus isolates from southwest of Iran using spa and SCCmec typing methods

Staphylococcus aureus remains a major cause of nosocomial infection worldwide. Characterization of S. aureus isolates circulating in the southwest of Iran will contribute to understand and control the spread of the strains in this area. spa and SCCmec typing methods were used for genotyping of 125 S. aureus isolates obtained from two teaching hospitals in Ahvaz. Drug susceptibility testing was performed by using disk diffusion method. Frequency of the methicillin resistant S. aureus (MRSA) isolates was 39% (n = 34) and 27% (n = 10) in Emam Khomeini and Golestan hospitals, respectively. Except for Erythromycin, MRSA strains showed high rate of resistance to antimicrobial agents including penicillin (100%), norfloxacine (80%), azitromycin (80%), ciprofloxacin (80%), gentamycin (77%), cotrimoxazole (75%), cephotaxime. All isolates were sensitive to vancomycin. Out of 44 MRSA strains, 39 (88.5%) were SCCmec III, three (7%) were IVc and two (4.5%) of them were nontypeable. spa types t037 (26 isolates; 59%), and t1149 (25 isolates; 31%) were the most dominant types found in MRSA and methicillin sensitive S. aureus (MSSA) strains, respectively. We found SCCmec type III as the most prominent type indicating that most of the studied bacterial population had hospital origin. spa type t037, the most frequent genotype in this study were significantly (100%) associated with MRSA. For the first time we are reporting spa types t692, t706 and t018 from Iran and t342, t704, t2622, t5598, t11270 and t2864 from Asia. Moreover we are reporting types t6871 and t2684 for the second time in the world.

Performance of MALDI biotyper compared with Vitek™ 2 compact system for fast identification and discrimination of Staphylococcus species isolated from bovine mastitis

This study was designed to evaluate the ability of MALDI Biotyper (MBT) compared with Vitek^™ 2 compact system for accurate identification of Staphylococcus aureus (S. aureus) and coagulase‐negative staphylococci (CNS) strains and discriminate methicillin‐sensitive S. aureus (MSSA) from methicillin‐resistant S. aureus (MRSA). Throughout Al‐Qassim region, Saudi Arabia, a total of 198 isolates of S. aureus (132 MSSA and 66 MRSA) and 44 CNS were collected from five dairy farms where the prevalence of staphylococcal mastitis was reported. The results produced by Vitek^™ 2 compact system demonstrated that 123/132 MSSA isolates (93.18%), 61/66 MRSA (92.42%), and 37/44 CNS species (84.09%) were correctly identified. However; 130/132 MSSA (98.48%), 64/66 MRSA (96.96%), and 44/44 CNS (100%) were correctly identified by MBT with score ≥2. 00. The principal component analysis (PCA) dendrogram generated by MBT illustrated that the tested isolates were classified into two groups of Staphylococcus species at the distance level of 600. S. aureus isolates were found to be closely related with higher peak intensities in the mass of 3,993 Da, 4,121 Da and 5,845 Da were detected in MRSA, whereas, that were lost in MSSA. Conclusion: This study verified that MBT is an alternative powerful tool for precise identification and discrimination of Staphylococcus species.

Clonal diversity and epidemiological characteristics of Staphylococcus aureus: high prevalence of oxacillin-susceptible mecA-positive Staphylococcus aureus (OS-MRSA) associated with clinical isolates in Brazil

Background

Staphylococcus aureus is the major cause of global and nosocomial infections with a significant impact in hospitals worldwide. Our objective was to investigate clinical and molecular characteristics of S. aureus isolates causing infections in patients admitted to hospitals from Recife city, Brazil, and investigate the prevalence of oxacillin-susceptible mecA-positive S. aureus (OS-MRSA) in the region, as well as genetically characterize the isolates and compare with epidemic clones.

Results

We characterized 89 isolates in total, 31 clinical methicillin-resistant S. aureus (MRSA) and 58 methicillin-sensitive (MSSA) isolates by PFGE, MLST, spa typing and SCCmec genotyping. Isolates belonging to international MRSA clones were present: Brazilian epidemic clone (BEC) (61 % of MRSA isolates), Paediatric (36 %), New York/Japan (3 %). Some MSSA isolates were related to MRSA clones: USA400-related (10 % of MSSA isolates), Berlin clone (2 %), Paediatric (14 %), New York/Japan (2 %) and Southwest Pacific clone (17 %). MLST revealed new sequence types (ST’s): ST2381, ST2382, and ST2383 and new spa types: 10548 and 10550. Among isolates phenotypically identified as MSSA by antimicrobial susceptibility assays, we verified 30 oxacillin-susceptible isolates, which exhibited the mecA gene, without mec complex amplification and were thus classified as OS-MRSA. We observed clonal spread of MRSA and MSSA, including OS-MRSA, within several areas of the main hospital investigated and closely related isolates between hospitals analyzed.

Conclusions

The results of this study suggest a possible spread of the strains in hospital environment that could be responsible for nosocomial infections. We documented the presence of several MRSA clones, as well as new MLST and spa types, that were responsible for severe infections in hospitalized patients. The finding of OS-MRSA isolates could have implications for therapy, because testing for mecA and PBP2a is not a routine procedure performed by clinical microbiology laboratories in Brazil and, as consequence, these isolates could be misclassified as MSSA. Our data alert to the necessity to develop more effective strategies for epidemiological control of S. aureus in order to avoid an increase of hospital infections provoked by this pathogen. We reinforce the use of genetic methods, in addition to phenotypic tests, for a precise identification of MRSA.

Electronic supplementary material

The online version of this article (doi:10.1186/s12866-016-0733-4) contains supplementary material, which is available to authorized users.

Molecular characterization of antimicrobial resistance genes against Staphylococcus aureus isolates from Trinidad and Tobago

Staphylococcus aureus continues to pose major public health challenges in many areas because of antibiotic resistance problems. In the Caribbean, especially Trinidad and Tobago, the challenge is not different. This study was performed to evaluate the antimicrobial resistance gene prevalence among S. aureus isolates in Trinidad and Tobago. Standard and molecular microbiological methods, including the Microscan automated system, DNA microarray and multi locus sequence typing (MLST) analysis, were performed on 309 clinical S. aureus isolates recovered from patients who were treated at three of the country's main health institutions. S. aureus exhibited susceptibilities ≥80% to eleven of the 19 antimicrobials tested against it, and these belong to the most commonly used and available antibiotics in the country. While the antibiotic to which it was most susceptible of the commonly used antibiotics was trimethoprim/sulfamethoxazole, the antibiotics to which it was least susceptible or most resistant to were ampicillin and penicillin. S. aureus isolates from the pediatric ward produced the greatest rate of susceptibility among the isolates recovered from patients admitted into hospitals, while isolates from Accident and Emergency rooms displayed the greatest susceptibilities among patients from the community. S. aureus isolates from the country did not harbor acquired resistant genes targeting clindamycin/macrolides (ermB), linezolid (cfr) or vancomycin (vanA). The blaZ gene, which is the most common beta lactam (Penicillinase) resistance mechanism for S. aureus, was observed in 88.7% of the methicillin susceptible S. aureus, while methicillin resistance mediated by the mec gene was present in 13.6%. Most of the resistance markers found in MRSA isolates were significantly associated with the ST239-MRSA-III strain in this study, and all isolates that belonged to the USA300 strain, which additionally encoded both the PVL gene and ACME cluster, belonged to CC8. Several resistant genes, such as vanA, cfr and ermB, mediating resistance in S. aureus, are currently non-existent in Trinidad and Tobago. However, the majority of SCCmec genes were observed, suggesting that there is ongoing nosocomial transmission with minimal community transmission. This calls for stringent antibiotic stewardship and policies in the country.

Antibiotic susceptibility and genomic variations in Staphylococcus aureus associated with Skin and Soft Tissue Infection (SSTI) disease groups

Background

Staphylococcus aureus is associated with human skin and soft tissue infections (SSTIs); however, the involvement of virulence factors in different clinical presentations is unclear.

Methods

We analyzed methicillin-resistant S. aureus (MRSA) and methicillin-sensitive S. aureus (MSSA) strains from Taiwan to determine correlations among the clinical characteristics of SSTIs, antimicrobial susceptibility and virulence factors of S. aureus with specific genetic backgrounds.

Results

We identified 177 MRSA isolates and 130 MSSA isolates among the 307 SSTI-associated S. aureus isolates. Hospital-acquired (HA)- and community-acquired (CA)-MRSA isolates accounted for 61.6 % and 38.4 % of the isolates, respectively. Clinical presentations in SSTI patients differed significantly for the disease groups. Deep-seated MRSA infections presented with higher amputation rate than MSSA infections. MRSA isolates were all susceptible to linezolid, teicoplanin, and vancomycin, and >94 % of isolates were erythromycin- and clindamycin-resistant. Staphylococcal cassette chromosome (SCCmec) types IV, V, and VII were the most frequent in the CA-MRSA group (n = 68); types III, IV and V were the most frequent in the HA-MRSA group (n = 109). Panton-Valentine leukocidin (PVL) genes were significantly more frequent in CA-MRSA strains (75.0 %) than in HA-MRSA (33.0 %) and MSSA (24.6 %) and were found in 66.7 % (74/111) strains isolated from the abscess group. Exfoliatin A genes were more common in catheter-related exit-site MSSA infections (37.5 %) compared with other MSSA disease groups (P < 0.05). Exfoliatin B and superantigen exotoxin genes were uncommon in all SSTI disease types. Pulsotypes A (ST239), C, and D (ST59) were the predominant MRSA genotypes in deep-seated infections.

Conclusions

If not treated appropriately, deep-seated MRSA-associated infections present with higher amputation rates than deep-seated MSSA-associated infections. PVL-positive MRSA strains caused more frequently pus-forming lesions and less bacteremia and invasive diseases. Methods for discriminating CA-MRSA from HA-MRSA strains are now unreliable due to circulation of both ST 239 and ST 59 strains in the community and nosocomial settings. Initial antibiotic treatments should consider MRSA for patients with SSTIs in areas where MRSA is prevalent.

Primary subacute hematogenous osteomyelitis in children: a clearer bacteriological etiology

BACKGROUND

This study aimed to describe the spectrum of pediatric primary subacute hematogenous osteomyelitis (PSAHO) and to investigate its bacterial etiology.

METHODS

Sixty-five consecutive cases of PSAHO admitted to our institution over a 16-year period (2000-2015) were retrospectively reviewed to assess their laboratory and radiographic imaging features, as well as their bacteriological etiology.

RESULTS

On evaluation, white blood cell count and C-reactive protein were normal in 53 (81.5 %) and 34 cases (52.3 %), respectively, whereas the erythrocyte sedimentation rate was superior to 20 mm/h in 44 cases (72.1 %). Blood cultures failed to identify the pathogen in all but one patient, and classic bone sample cultures only managed to isolate the pathogen in five cases (11.6 %). Use of polymerase chain reaction (PCR) assays on bone aspirates or blood allowed the causative microorganism to be isolated in a further 22 cases. Using classic cultures and PCR assays together resulted in pathogen detection in 27 cases (62.8 % of the children bacteriologically investigated), with Kingella kingae being the most frequently reported microorganism.

CONCLUSIONS

Two distinct forms of PSAHO should be distinguished on the basis of age of patients and bacteriological etiology. The infantile form affects children aged between 6 months and 4 years and is predominantly due to K. kingae. The juvenile form involves children aged >4 years and Staphylococcus aureus appears to be the main bacteriological etiology. Appropriate nucleic amplification assays drastically improve the detection rate of the microorganisms responsible for PSAHO.

LEVEL OF EVIDENCE

Case series, level IV.

Poor outcomes of empiric ceftriaxone ± azithromycin for community-acquired pneumonia caused by methicillin-susceptible Staphylococcus aureus

While ceftriaxone 1 g q24h is commonly used for hospitalized patients with community-acquired pneumonia (CAP), the prescribing information recommends 2-4 g a day to treat methicillin-susceptible Staphylococcus aureus (MSSA). Similarly, recent pharmacodynamic analyses suggest shortcomings of 1 g q24h against the bulk of the MSSA. We evaluated the outcomes of empiric ceftriaxone 1 g q24h ± azithromycin in patients with MSSA pneumonia, as compared with Streptococcus pneumoniae. Adult patients admitted to Hartford Hospital from 1/2005 to 12/2014 with respiratory culture for MSSA or S. pneumoniae were considered for inclusion. Non-ICU, CAP patients were included. Early clinical failure (ECF) was defined as persistent signs/symptoms or change of antibiotic due to poor response at 72-96 h. A multivariate analysis was performed to evaluate predictors of ECF. Over the study period, 403 MSSA and 227 S. pneumoniae positive respiratory cultures were identified. The majority of patients were excluded due to the following: no signs/symptoms of pneumonia, hospital-acquired pneumonia, alternative antibiotics, and polymicrobial infection. Thirty-nine patients met inclusion/exclusion criteria. All but three patients in the S. pneumoniae group received ceftriaxone + azithromycin. ECF was greater in the MSSA group (53 vs. 4 %, P = 0.003), as was length of stay (7.5 ± 5.4 vs. 4.6 ± 3.3 days, P = 0.006). When controlling for disease severity and macrolide non-susceptibility in a multivariate analysis, MSSA was significantly correlated with ECF (OR 12.3, 95 % CI 0.8-188.8). Poor clinical outcomes were observed in patients empirically treated with ceftriaxone ± azithromycin for MSSA CAP. Despite the popularity of ceftriaxone 1 g q24h, these data suggest this dose or compound may be inadequate for CAP caused by MSSA.

Methicillin-Susceptible, Vancomycin-Resistant Staphylococcus aureus, Brazil

We report characterization of a methicillin-susceptible, vancomycin-resistant bloodstream isolate of Staphylococcus aureus recovered from a patient in Brazil. Emergence of vancomycin resistance in methicillin-susceptible S. aureus would indicate that this resistance trait might be poised to disseminate more rapidly among S. aureus and represents a major public health threat.

PCR-based Approaches for the Detection of Clinical Methicillin-resistant Staphylococcus aureus

Staphylococcus aureus is an important pathogen that can cause a variety of infections, including superficial and systematic infections, in humans and animals. The persistent emergence of multidrug resistant S. aureus, particularly methicillin-resistant S. aureus, has caused dramatically economic burden and concerns in the public health due to limited options of treatment of MRSA infections. In order to make a correct choice of treatment for physicians and understand the prevalence of MRSA, it is extremely critical to precisely and timely diagnose the pathogen that induces a specific infection of patients and to reveal the antibiotic resistant profile of the pathogen. In this review, we outlined different PCR-based approaches that have been successfully utilized for the rapid detection of S. aureus, including MRSA and MSSA, directly from various clinical specimens. The sensitivity and specificity of detections were pointed out. Both advantages and disadvantages of listed approaches were discussed. Importantly, an alternative approach is necessary to further confirm the detection results from the molecular diagnostic assays.

Treating Staphylococcus aureus infections in an intensive care unit at a University Hospital in Brazil

BACKGROUND

Optimizing antimicrobial therapy is important for treating patients who are critically ill with Staphylococcus aureus infection, and susceptibility tests are necessary.

OBJECTIVE

The aim of the present study was to evaluate antibacterial therapy after susceptibility testing of S. aureus infections. Setting The setting was an intensive care unit at a University Hospital in Brazil.

METHODS

An observational and retrospective study was conducted over 6 years. The antimicrobials that were used for S. aureus infection treatment were calculated as the defined daily dose per 1000 patient-days (DDD1000). Antimicrobial susceptibility data were obtained by reviewing bacteriological tests. Patient profiles and treatment were determined by analyzing patient charts.

RESULTS

Methicillin-resistant S. aureus (MRSA) was prevalent in this study (76.13 %). Patients who were infected with MRSA had total antimicrobial consumption that was three-times higher (9567.2 DDD1000) than patients who were infected with methicillin-susceptible S. aureus (MSSA; 3101.1 DDD1000). The average length of stay in the intensive care unit was 19 days (interquartile range 17 days) for MSSA and 20 days (interquartile range 20 days) for MRSA. Mortality in patients who were infected with MSSA was higher (52.17 %) than in patients who were infected with MRSA (33.80 %), and de-escalation was not identified in 73.90 % of MSSA patients.

Clonal diversity of methicillin-sensitive Staphylococcus aureus from South Australian wallabies

Seven methicillin-sensitive Staphylococcus aureus nasal isolates from apparently healthy captive and wild wallabies were characterised by DNA microarray and antibiotic susceptibility assays. Isolates were found to belong to uncommon clonal complexes including those previously associated with birds, pigs and humans.

•

First study of commensal staphylococci in apparently healthy Australian macropods.

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Resistance and virulence genes were rare in these MSSA isolates.

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Recent transmission of MSSA-CC15 from humans to wallabies.

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“Australian” S. aureus clones ST93 and ST1850 were not recovered.

Beyond the Intensive Care Unit (ICU): Countywide Impact of Universal ICU Staphylococcus aureus Decolonization

A recent trial showed that universal decolonization in adult intensive care units (ICUs) resulted in greater reductions in all bloodstream infections and clinical isolates of methicillin-resistant Staphylococcus aureus (MRSA) than either targeted decolonization or screening and isolation. Since regional health-care facilities are highly interconnected through patient-sharing, focusing on individual ICUs may miss the broader impact of decolonization. Using our Regional Healthcare Ecosystem Analyst simulation model of all health-care facilities in Orange County, California, we evaluated the impact of chlorhexidine baths and mupirocin on all ICU admissions when universal decolonization was implemented for 25%, 50%, 75%, and 100% of ICU beds countywide (compared with screening and contact precautions). Direct benefits were substantial in ICUs implementing decolonization (a median 60% relative reduction in MRSA prevalence). When 100% of countywide ICU beds were decolonized, there were spillover effects in general wards, long-term acute-care facilities, and nursing homes resulting in median 8.0%, 3.0%, and 1.9% relative MRSA reductions at 1 year, respectively. MRSA prevalence decreased by a relative 3.2% countywide, with similar effects for methicillin-susceptible S. aureus. We showed that a large proportion of decolonization's benefits are missed when accounting only for ICU impact. Approximately 70% of the countywide cases of MRSA carriage averted after 1 year of universal ICU decolonization were outside the ICU.

Staphylococcus aureus in Animals and Food: Methicillin Resistance, Prevalence and Population Structure. A Review in the African Continent

The interest about Staphylococcus aureus (S. aureus) and methicillin resistant S. aureus (MRSA) in livestock, and domestic and wild animals has significantly increased. The spread of different clonal complexes related to livestock animals, mainly CC398, and the recent description of the new mecC gene, make it necessary to know more about the epidemiology and population structure of this microorganism all over the world. Nowadays, there are several descriptions about the presence of S. aureus and/or MRSA in different animal species (dogs, sheep, donkeys, bats, pigs, and monkeys), and in food of animal origin in African countries. In this continent, there is a high diversity of ethnicities, cultures or religions, as well as a high number of wild animal species and close contact between humans and animals, which can have a relevant impact in the epidemiology of this microorganism. This review shows that some clonal lineages associated with humans (CC1, CC15, CC72, CC80, CC101, and CC152) and animals (CC398, CC130 and CC133) are present in this continent in animal isolates, although the mecC gene has not been detected yet. However, available studies are limited to a few countries, very often with incomplete information, and many more studies are necessary to cover a larger number of African countries.

Clonal complex 398 methicillin-susceptible Staphylococcus aureus bloodstream infections are associated with high mortality

Within the last decade, methicillin-resistant Staphylococcus aureus belonging to clonal complex 398 (CC398) has become a worldwide threat associated with livestock. More recently, methicillin-susceptible S. aureus (MSSA) belonging to CC398 have been increasingly reported as a cause of invasive infections in patients without livestock contact. We investigated risk factors associated with CC398 bloodstream infections (BSIs) compared with non-CC398 BSIs with a case-control study in a French university Hospital. From January 2010 to December 2014, nonduplicate Staphylococcus aureus (SA) isolates responsible for BSIs in adult patient were typed to identify those belonging to CC398. Each adult patient with a CC398 SA BSI (cases) was matched with 2 non-CC398 SA BSI controls randomly selected on the basis of the time at risk, the unit of hospitalization and susceptibility to methicillin. We retrospectively extracted the clinical information from electronic medical records and used conditional logistic regression for univariate and multivariate analyses. We identified 67 CC398 isolates among the 770 SA responsible for BSI in adult patients. All CC398 isolates were susceptible to methicillin. The proportion of CC398 among MSSA increased steadily from 4.6% in 2010 to 15.1% in 2013 and then stabilized at 13.8% in 2014. Factors significantly associated with CC398 MSSA BSIs were healthcare-associated infection (odds ratio (OR) 3.02, 95% confidence interval (CI) 1.19-7.63), history of neurologic disease (OR 2.51, 95% CI 1.13-5.65) and 30-day mortality (OR 2.44, 95% CI 1.23-4.85).

Flucloxacillin does not achieve therapeutic cerebrospinal fluid levels against meticillin-sensitive Staphylococcus aureus in adults: A case report and review of the literature

It is uncertain whether flucloxacillin achieves therapeutic concentrations against meticillin-sensitive Staphylococcus aureus (MSSA) in cerebrospinal fluid (CSF). In this study, plasma and CSF concentrations of flucloxacillin and vancomycin in an adult patient were compared. Unlike vancomycin, the flucloxacillin CSF level was not therapeutic. Flucloxacillin monotherapy should be used with caution for MSSA central nervous system infection in adults.

Recurrent skin infection associated with nasal carriage of Panton-Valentine leukocidin-positive methicillin-susceptible Staphylococcus aureus closely related to the EMRSA-15 clone

We report the case of a soldier with recurrent skin infection associated with nasal carriage of a Panton-Valentine leukocidin (PVL)-producing methicillin-susceptible Staphylococcus aureus (MSSA), closely related to the EMRSA-15 clone. MSSA isolates causing infection not requiring hospitalization usually go unnoticed; however, their typing may be useful to understand the global distribution of successful staphylococcal lineages related to epidemic clones. PVL-positive MSSA strains might serve as reservoirs from which virulent methicillin-resistant strains may evolve and spread.

Elution of antibiotics from poly(methyl methacrylate) bone cement after extended implantation does not necessarily clear the infection despite susceptibility of the clinical isolates

Chronic orthopedic infections are commonly caused by bacterial biofilms, which are recalcitrant to antibiotic treatment. In many cases, the revision procedure for periprosthetic joint infection or trauma cases includes the implantation of antibiotic-loaded bone cement to kill infecting bacteria via the elution of a strong local dose of antibiotic(s) at the site. While many studies have addressed the elution kinetics of both non-absorbable and absorbable bone cements both in vitro and in vivo, the potency of ALBC against pathogenic bacteria after extended implantation time is not clear. In this communication, we use two case studies, a Viridans streptococci infected total knee arthroplasty (TKA) and a MRSA-polymicrobial osteomyelitis of a distal tibial traumatic amputation (TA) to demonstrate that an antibiotic-loaded poly(methyl methacrylate) (ALPMMA) coated intermedullary rod implanted for 117 days (TKA) and three ALPMMA suture-strung beads implanted for 210 days (TA) retained killing ability against Pseudomonas aeruginosa and Staphylococcus aureus in vitro, despite different clinical efficacies. The TKA infection resolved and the patient progressed to an uneventful second stage. However, the TA infection only resolved after multiple rounds of debridement, IV vancomycin and removal of the PMMA beads and placement of vancomycin and tobramycin loaded calcium sulfate beads.

Treatment of methicillin-sensitive Staphylococcus aureus bacteremia secondary to septic phlebitis using dalbavancin

WHAT IS KNOWN AND OBJECTIVE

Treatment of bacteremia due to Staphylococcus aureus often requires prolonged therapy leading to increased hospital lengths of stay and associated costs. For certain patients, referral to an outpatient parenteral antimicrobial therapy (OPAT) programme serves as an alternative to increased inpatient length of stay. We report an alternative to OPAT using dalbavancin for the treatment of methicillin-sensitive Staphylococcus aureus (MSSA).

CASE SUMMARY

A 54-year-old Caucasian man was brought to the emergency department from a rehabilitation centre with altered mental status and possible seizure. A peripheral intravenous catheter was placed in the left forearm, and the patient was transferred to the intensive care unit (ICU) for management of his acute psychosis, possible seizure and hyponatremia. Seven days into admission, the patient became febrile thought to be secondary to septic phlebitis of the forearm. Blood cultures were taken and organism identification using Nanosphere Verigene^® BC-GP rapid diagnostic testing resulted in MSSA. The patient received treatment with cefazolin with a planned treatment duration of 14 days but because of the patient's history of alcohol abuse, psychosis requiring hospitalization via the Baker Act, and history of non-compliance to follow-up appointments, the patient was deemed ineligible for OPAT. Due to the limited treatment options, therapy for MSSA bacteremia was changed on day 6 of cefazolin therapy to dalbavancin to complete the 14-day treatment duration. Blood cultures were negative at the end of treatment and no relapse of infection occurred.

WHAT IS NEW AND CONCLUSION

To our knowledge, this is the first case report using dalbavancin in clinical practice for the treatment of MSSA bacteremia secondary to septic phlebitis. This report highlights the potential role of the newer lipoglycopeptides, such as dalbavancin, in treating patients who require long-term parenteral antimicrobial therapy and are ineligible for treatment via OPAT.

Comparative effectiveness of beta-lactams versus vancomycin for treatment of methicillin-susceptible Staphylococcus aureus bloodstream infections among 122 hospitals

BACKGROUND

Previous studies indicate that vancomycin is inferior to beta-lactams for treatment of methicillin-susceptible Staphylococcus aureus (MSSA) bloodstream infections. However, it is unclear if this association is true for empiric and definitive therapy. Here, we compared beta-lactams with vancomycin for empiric and definitive therapy of MSSA bloodstream infections among patients admitted to 122 hospitals.

METHODS

This retrospective cohort study included all patients admitted to Veterans Affairs hospitals from 2003 to 2010 who had positive blood cultures for MSSA. Hazard ratios (HR) and 95% confidence intervals (CIs) were calculated using Cox proportional hazards regression. Empiric therapy was defined as starting treatment 2 days before and up to 4 days after the first MSSA blood culture was collected. Definitive therapy was defined as starting treatment between 4 and 14 days after the first positive blood culture was collected.

RESULTS

Patients who received empiric therapy with a beta-lactam had similar mortality compared with those who received vancomycin (HR, 1.03; 95% CI, .89-1.20) after adjusting for other factors. However, patients who received definitive therapy with a beta-lactam had 35% lower mortality compared with patients who received vancomycin (HR, 0.65; 95% CI, .52-.80) after controlling for other factors. The hazard of mortality decreased further for patients who received cefazolin or antistaphylococcal penicillins compared with vancomycin (HR, 0.57; 95% CI, .46-.71).

CONCLUSIONS

For patients with MSSA bloodstream infections, beta-lactams are superior to vancomycin for definitive therapy but not for empiric treatment. Patients should receive beta-lactams for definitive therapy, specifically antistaphylococcal penicillins or cefazolin.

Design, synthesis and biological evaluation of 4-benzoyl-1-dichlorobenzoylthiosemicarbazides as potent Gram-positive antibacterial agents

Twelve 4-benzoyl-1-dichlorobenzoylthiosemicarbazides have been tested as potential antibacterials. All the compounds had MICs between 0.49 and 15.63 µg/ml toward Micrococcus luteus, Bacillus cereus, Bacillus subtilis and Staphylococcus epidermidis indicating, in most cases, equipotent or even more effective action than cefuroxime. In order to clarify if the observed antibacterial effects are universal, further research were undertaken to test inhibitory potency of two most potent compounds 3 and 11 on clinical isolates of Staphylococcus aureus. Compound 11 inhibited the growth of methicillin-sensitive S. aureus (MSSA) at MICs of 1.95-7.81 µg/ml, methicillin-resistant S. aureus (MRSA) at MICs of 0.49-1.95 µg/ml and MDR-MRSA at MIC of 0.98 and 3.90 µg/ml, respectively. Finally, inhibitory efficacy of 3 and 11 on planktonic cells and biofilms formation in clinical isolates of S. aureus and Haemophilus parainfluenzae was tested. The majority of cells in biofilm populations of MSSA and MRSA were eradicated at low level of 3, with MBICs in the range of 7.82-15.63 µg/ml.

A report on infection dynamics of inducible clindamycin resistance of Staphylococcus aureus isolated from a teaching hospital in India

OBJECTIVE

To investigate the infection of hospital- and community-acquired "erythromycin-induced clindamycin resistant" strains or D-test positives of clinical isolates of Staphylococcus aureus (S. aureus) (with and without methicillin resistance) in a hospital.

METHODS

Strains of S. aureus isolated from clinical specimens were subjected to D-test and antibiotic profiling.

RESULTS

Of the total 278 isolates, 140 (50.35%) were D-test positives and the rest were D-test negatives. Further, of 140 (100%) positives, 87 (62.14%) and 53 (37.85%) strains were from males and females, respectively. Of 140 (100%) positives, 117 (83.57%) were methicillin resistant S. aureus and 23 (16.42%) were methicillin sensitive S. aureus; of 140 strains, 103 (73.57%) strains from persons with and 37 (26.42%) were without related infections; of 140 strains, 91 (65%) and 49 (35%) were from hospital- and community-acquired samples, respectively. In 140 strains, 118 (84.28%) with comorbidities and 22 (15.71%) without comorbidities cases were recorded; similarly, persons with prior antibiotic uses contributed 108 (77.14%) and without 32 (22.85%) positive strains. These binary data of surveillance were analyzed by a univariate analysis. It was evident that the prior antibiotic uses and comorbidities due to other ailments were the determinative factors in D-test positivity, corroborated by low P values, P=0.001 1 and 0.002 4, respectively. All isolates (278) were resistant to 17 antibiotics of nine groups, in varying degrees; the minimum of 28% resistance for vancomycin and the maximum of 97% resistance for gentamicin were recorded. Further, of 278 strains, only 42 (15.1%) strains were resistant constitutively to both antibiotics, erythromycin resistant and clindamycin resistant, while 45 (16.2%) strains were constitutively sensitive to both antibiotics (erythromycin sensitive and clindamycin sensitive). Further, of the rest 191 (68.7%) strains were with erythromycin resistant and clindamycin resistant, of which only 140 (50.35%) strains were D-test positives, while the rest 51 (18.34%) strains were D-test negatives.

CONCLUSIONS

In view of high prevalence of D-test positive S. aureus strains, and equally high prevalence of multidrug resistant strains both in community and hospital sectors, undertaking of D-test may be routinely conducted for suppurative infections.

Prevalence of Panton-Valentine leukocidin-positive methicillin-susceptible Staphylococcus aureus infections in a Saudi Arabian hospital

Panton-Valentine leukocidin (PVL) is a two-component toxin associated with the toxicity and virulence of Staphylococcus aureus. The presence of PVL is well documented in community-acquired methicillin-resistant S. aureus (CA-MRSA) and is observed in methicillin-susceptible S. aureus (MSSA) with variable prevalence. We assessed the prevalence of PVL in a sample of 93 MSSA patients in a healthcare facility in Eastern Saudi Arabia using real-time PCR for lukSF-PV genes. The presence or absence of PVL was correlated with age, gender, hospitalization status, infection site and antibiotic resistance. PVL was detected in 28 (30%) patient samples. PVL was associated with a greater likelihood of resistance to trimethoprim-sulfamethoxazole (a resistance of 39.2% of PVL-positive isolates compared to 6.1% of PVL-negative isolates) (p < 0.0007). These results suggest a significant prevalence of PVL expression in MSSA strains in the study population and call for monitoring of and surveillance programs for PVL status and the selection of appropriate antibiotic treatments.

The distribution of pathogenic and toxigenic genes among MRSA and MSSA clinical isolates

Staphylococcus aureus (S. aureus) is considered as a notorious nosocomial pathogen among hospitalized patients and community-dwelling subjects. Its increasing morbidity and mortality is believed to be due to antibiotic resistance. However, the data concerning molecular properties of infecting strains are few. In this study, a total of 192 S. aureus strains, including 88 (45.8%) meticillin-sensitive S. aureus (MSSA) and 104 (54.2%) meticillin-resistant S. aureus (MRSA) were recovered from clinical samples. The prevalence of subtypes containing staphylococcal cassette chromosome mec (SSCmec), staphylococcal enterotoxins (SEs), toxic shock syndrome toxin (TSST) and exfoliative toxin was assessed by PCR. Antibiotic susceptibility pattern and vancomycin resistance of each isolate were evaluated by disk diffusion method and micro-dilution method, respectively. 9 (2.3%) strains required MIC > 2 mg/l of vancomycin, which significantly increased among multi drug resistant (MDR), MRSA and SCCmec type III strains (p < 0.05). 171 (89%), 140 (72.91%), 7 (3.6), 78 (48.6%), 5 (2.6%), 151 (78.64%), 129 (67.18%), 178 (92.7%) and 15 (7.8%) of 192 isolates harbored mecA, entA, entB, entC, entD, entE, eta, etb and tsst-1 genes, respectively. 31 (16.14%), 5 (2.6%), 95 (49.48%) and 7 (3.64%) of 192 isolates carried SCCmec type I, II, III and IV, respectively. We found a significantly higher rate of MRSA and resistance to all tested antibiotics, except to penicillin G, kanamycin and linezolide among the SCCmec type III class (p < 0.05). According to our findings, MSSA isolates should be taken as seriously as MRSA strains due to the potential presence of broad spectrum virulence factor genes.

Chemical composition, antioxidant activity and in vitro antibacterial activity of Achillea wilhelmsii C. Koch essential oil on methicillin-susceptible and methicillin-resistant Staphylococcus aureus spp

The present study investigated the chemical composition of the essential oil (EO) from aerial parts (flowering stage) of Achillea wilhelmsii C. Koch by GC–MS. In addition, the antioxidant activity of the EO as well as its antimicrobial activity against methicillin-susceptible and methicillin-resistant Staphylococcus aureus (MRSA) strains was tested. Antioxidant activity was measured by the ability of the EO to scavenge 1,1-diphenyl-2-picrylhydrazyl (DPPH) radicals while the antimicrobial activity was assessed by the disc-diffusion method. In total, 52 compounds were recognized, accounting for 97.33 % of the EO. The main compounds in the EO were carvacrol (22.49 %), dihydrocarvone (13.23 %), linalool (12 %), 1,8-cineol (11.42 %), camphene (8.31 %), thymol (5.28 %), camphor (3.71 %), pulegone (2.82 %) α-terpineol (2.11 %), bornyl acetate (1.14 %), and farganol (1.01 %). The EC₅₀ value of the EO was 0.01 and 0.08 mg/mL for the antioxidant and DPPH-scavenging ability, respectively. A. wilhelmsii EO affected methicillin-sensitive Staphylococcus aureus (MSSA) and MRSA, but the impact was more effective on MSSA.

Clinical and bacteriological efficacy of twice daily topical retapamulin ointment 1% in the management of impetigo and other uncomplicated superficial skin infections

BACKGROUND

Cutaneous bacterial infections are common in children and adults and frequently are caused by Staphylococcus aureus (S. aureus). Treatment failures with topical agents are not uncommon and have been shown to be secondary to bacterial resistance.

OBJECTIVE

To determine clinical and bacteriological efficacy of retapamulin ointment 1% in treatment of patients with cutaneous bacterial infections caused by methicillin-resistant S. aureus (MRSA) and other bacteria.

METHODS

Prospective, nonrandomized, uncontrolled, open label, single center trial conducted between April 2008 and November 2012 that evaluated efficacy of retapamulin ointment 1% in the treatment of impetigo, folliculitis, and other minor soft tissue infections in children and adults. Fifty patients, who presented to a dermatology outpatient clinic and were clinically diagnosed with impetigo, folliculitis, or minor soft tissue infection suitable for treatment with a topical antibiotic, were screened. Thirty-eight patients were enrolled and received treatment: topical retapamulin ointment 1% twice daily for 5 days. Seven patients were MRSA positive and qualified for the primary efficacy population. One patient withdrew due to an adverse event. Clinical and microbiological exams were performed at baseline and follow-up 5 to 7 days later to assess clinical, microbiological, and therapeutic responses. Primary outcome was clinical response at follow-up in primary efficacy population with MRSA isolated as the baseline pathogen. Secondary outcomes included clinical, microbiologic, and therapeutic responses in patients who were culture positive for any species of bacteria.

RESULTS

Clinical response at follow-up in the primary efficacy population (MRSA-positive patients) was not sufficiently powered to demonstrate significance; however, outcomes were excellent, with 7 of 7 patients demonstrating clinical success (5 of 7) or clinical improvement (2 of 7) at follow-up. Barring lack of significance due to small total sample size for patients who were culture positive for any species of bacteria (n = 35), overall success rates were favorable for clinical, microbiologic, and therapeutic responses with values of 66%, 97%, and 69%, respectively. Adverse events (AEs) were mild or moderate in severity. No serious AEs were reported.

CONCLUSION

Safety profile appears favorable given the low number of AEs. Study design limits conclusions that can be drawn. Nevertheless, this study supports use of topical retapamulin 1% ointment in treatment of cutaneous bacterial infections, particularly those caused by S. aureus, including MRSA.

Meticillin-resistant Staphylococcus aureus and meticillin-susceptible Staphylococcus aureus screening in a cohort of haemodialysis patients: carriage, demographics and outcomes

BACKGROUND

Patients on haemodialysis are vulnerable to colonization with Staphylococcus aureus due to frequent hospital contact, indwelling devices, and impaired immunity. Additionally colonization is associated with increased risk of infection.

AIM

To determine the prevalence of both meticillin-resistant S. aureus (MRSA) and meticillin-susceptible S. aureus (MSSA) carriage in our haemodialysis cohort and to identify any risk factors predisposing to carriage, recolonization, or persistent carriage following a decolonization programme.

METHODS

All haemodialysis patients screened for S. aureus carriage between June 2009 and May 2011 were retrospectively followed up for 18 months using hospital electronic records. Statistical analysis was performed using IBM SPSS version 19.

FINDINGS

Out of 578 patients screened, 288 patients (49%) had at least one positive swab (10% MRSA, 90% MSSA). Of these patients, 265 completed a course of decolonization therapy following which 36% successfully eradicated (eradicators) and 64% did not (non-eradicators). There was no statistically significant difference in patient demography, type of vascular access, 18-month patient mortality, or number of hospital admissions between the two groups. Those who failed to eradicate were more likely to have had an episode of S. aureus bacteraemia within the study period compared to those who successfully decolonized (P = 0.003).

CONCLUSION

Half of our haemodialysis cohort was colonized with S. aureus at any one time over an 18-month period. Following decolonization, one-third of patients remained successfully eradicated for 18 months. Non-eradicators have an increased risk of bacteraemia, which is associated with poor mortality. We would recommend routine screening and aggressive attempts to decolonize.

Panton-Valentine leukocidin in community and hospital-acquired Staphylococcus aureus strains

Staphylococcus aureus causes serious hospital-acquired (HA) and community-acquired (CA) infections. Skin and soft-tissue infections especially are sometimes caused by strains harbouring Panton-Valentine leukocidin (PVL). PVL belongs to a family of bi-component leukocidal toxins produced by staphylococci. It is a pore-forming toxin encoded by lukF-PV and lukS-PV. A total of 70 S. aureus strains: 38 (54%) methicillin-resistant (MRSA) and 32 (46%) methicillin-susceptible (MSSA), were isolated from patients admitted to Dicle University Hospital (Turkey). Identification of S. aureus and antibiotics-susceptibility testing were performed with PHOENIX 100. PVL genes and mecA genes were detected by polymerase chain reaction. Of the 70 studied strains, 36 ones (51%) were community acquired and 34 ones (49%) were hospital acquired . A total of 38 (54%) strains were positive for mecA (mecA⁺), of which 32 ones (84%) were HA. Of the mecA⁻ strains, 30 (94%) were CA. Of the 70 studied strains, 12 (17%) strains were PVL⁺: 8 (22%) of the 36 CA strains and 4 (12%) of the 34 HA strains. Of the 12 PVL⁺ strains, 4 strains were mecA⁺. The PVL positivity rate was 25% in MSSA, whereas 10.5% in MRSA. Of the overall PVL⁺ strains, seven strains were obtained from wounds; four ones from skin abscess; and one from blood culture. Taken together, the obtained results showed a substantial level of PVL genes in the studied region. Although PVL is known as a common virulence factor of CA MRSA, HA MRSA isolates in our study showed a considerable rate of PVL positivity.

Nasal carriage of coagulase positive staphylococci in patients of a Primary-Healthcare-Center: genetic lineages and resistance and virulence genes

INTRODUCTION

Staphylococcus aureus and Staphylococcus pseudintermedius are highly important due to their capacity for producing diseases in humans and animals, respectively. The aim of the study was to investigate and characterize the coagulase positive Staphylococcus (CoPS) carriage in a Primary Healthcare Center population.

METHODS

Nasal swabs were obtained from 281 non-infectious patients. The CoPS isolates recovered were typed, and their resistance phenotype and genotype, as well as their virulence profiles, were analyzed.

RESULTS

CoPS isolates were recovered from 56/281 patients (19.9%). Fifty-five were S. aureus (19.6%), 54 were methicillin susceptible (MSSA) and one was methicillin resistant (MRSA). The remaining isolate was S. pseudintermedius (0.4%). A high diversity of spa-types (n=40) was detected, with 6 of them being new ones. The multi-locus-sequence-typing of 13 MSSA and one MRSA selected isolates was performed and the STs detected were: ST8, ST15, ST30, ST34, ST121, ST146, ST398, ST554, ST942, ST2499, and ST2500 (the last two STs being new). One MSSA isolate was typed as t1197-ST398-(Clonal complex)CC398. The MRSA isolate was typed as t002-ST146-CC5-SCCmec-IVc, and exhibited a multiresistance phenotype. The detected resistances were: penicillin (76%), macrolides (7%), tetracycline (7%), trimethoprim-sulfamethoxazole (7%), quinolones (7%), and lincosamides (5%). Five isolates contained lukF/lukS-PV genes, 17 tst gene, one eta gene, and two etb gene. The S. pseudintermedius isolate presented a new spa-type (t57) (belonging to a new ST180) and the genes lukS/F-I, siet, se-int, and expB.

CONCLUSIONS

A high genetic diversity of S. aureus was detected. Mention must be made of the identification of MSSA CC398 and S. pseudintermedius isolates in two patients, one of them with animal contact. The detection of the genes lukF/lukS-PV and tst should be noted.

High rate of inducible clindamycin resistance in Staphylococcus aureus isolates--a multicenter study in Tokyo, Japan

The resistance of Staphylococcus aureus (S. aureus) to antibiotics is an increasing problem. Clindamycin has been used as empiric therapy for the rising incidence of community-acquired methicillin-resistant S. aureus (MRSA). As such, the local rate of inducible resistance against clindamycin is an important consideration. This multicenter study was conducted to identify the incidence of inducible clindamycin resistance of S. aureus isolates in Tokyo, the most populous city in Japan. A total of 2408 adult and pediatric samples were collected from a university hospital and two pediatric hospitals between January 2011 and December 2011. Among the 2341 samples analyzed, the incidence of inducible clindamycin resistance in erythromycin-resistant and clindamycin-susceptible/intermediate isolates was found to be 91% (n = 585), a figure much higher compared to most reports from other countries. In conclusion, we found a very high rate of inducible clindamycin resistance in macrolide-resistant S. aureus isolates in our geographic area.

A randomized phase 2 study comparing two doses of delafloxacin with tigecycline in adults with complicated skin and skin-structure infections

BACKGROUND

A randomized, double-blind, multicenter trial was done to compare two doses of delafloxacin with tigecycline in patients with various complicated skin and skin-structure infections (wound infections following surgery, trauma, burns, or animal/insect bites, abscesses, and cellulitis).

METHODS

Patients were randomized 1:1:1 to receive delafloxacin 300mg intravenous (IV) every 12h, delafloxacin 450mg IV every 12h, or tigecycline 100mg IV×1, followed by 50mg IV every 12h; randomization was stratified by infection type. Duration of therapy was 5-14 days. The primary efficacy analysis, performed on the clinically evaluable (CE) population at the test-of-cure (TOC) visit (14-21 days after the final dose of study drug), compared clinical response rates in the delafloxacin and tigecycline arms. Clinical response rates in the two delafloxacin arms were also compared.

RESULTS

Among CE patients, clinical cure rates at TOC visit were similar in the delafloxacin and tigecycline arms (94.3%, 92.5%, and 91.2%, respectively in delafloxacin 300-mg, delafloxacin 450-mg, and tigecycline arms). Overall, the most frequent adverse events were nausea, vomiting, and diarrhea; the 300-mg delafloxacin arm was the best-tolerated regimen.

CONCLUSIONS

Delafloxacin was similarly effective as tigecycline for a variety of complicated skin and skin-structure infections and was well tolerated. (Clinicaltrials.gov NCT 0719810).

Septic arthritis in intravenous drug abusers: a historical comparison of habits and pathogens

BACKGROUND

Intravenous drug abuse (IVDA) is a common problem; there were more than 16 million users worldwide in 2008. Numerous reports highlight the infectious skeletal complication associated with IVDA.

OBJECTIVE

To determine septic arthritis pathogens in IVDA in a U.S. hospital and compare the current causative organisms to a cohort from the 1980s at the same institution.

METHODS

An institutional review board-approved retrospective cohort study compared a consecutive series of IVDA septic arthritis patients over a 10-year period, 1999-2008 (Group B), with an IVDA septic arthritis database that was collected in the 1980s (Group A). Endpoints were: bacterial species and staph species antibiotic susceptibility.

RESULTS

Group B included 58 patients (35 men, 23 women) with a median age of 46.5 years. Group A included 38 patients (30 men, 8 women), with a median age of 32.5 years. The sets were significantly different in pathogens (p = 0.0443). The most common organisms were Staphylococcus (staph) species (B 74.51%, A 52.63%), followed by Streptococcus (strep) species (B 7.84%, A 31.58%), Pseudomonas (B 13.73%, A 13.16%), and Serratia (B 3.92%, A 2.63%). Of the total number of septic joints, methicillin-resistant Staphylococcus aureus (MRSA) made up 39% of Group B and 34% of Group A. However, within the staph species, MRSA made up 53% of Group B and 65% of Group A. Strep species made up 7.84% (Group B) vs. 31.58% (Group A), and Pseudomonas (13%) and Serratia (3-4%) were similar. In the Group B cohort, methicillin-susceptible Staphylococcus aureus (MSSA) had a predilection to infect the knee (94.4%), whereas MRSA was found more often in the hip (57.1%).

CONCLUSIONS

In IVDAs, MRSA is the most common pathogen causing septic arthritis. The ratio of staph species in septic joints is increasing, and the ratio of MRSA to MSSA remains high (>50%). Strep species are much less common.

Antimicrobial salvage therapy for persistent staphylococcal bacteremia using daptomycin plus ceftaroline

PURPOSE

Guidelines recommend daptomycin combination therapy as an option for methicillin-resistant Staphylococcus aureus (MRSA) bacteremia after vancomycin failure. Recent data suggest that combining daptomycin with a β-lactam may have unique benefits; however, there are very limited clinical data regarding the use of ceftaroline with daptomycin.

METHODS

All 26 cases from the 10 medical centers in which ceftaroline plus daptomycin was used for treatment of documented refractory staphylococcal bacteremia from March 2011 to November 2012 were included. In vitro (synergy studies, binding assays, cathelicidin LL-37 killing assays), and in vivo (virulence assays using a murine subcutaneous infection model) studies examining the effects of ceftaroline with daptomycin were also performed.

FINDINGS

Daptomycin plus ceftaroline was used in 26 cases of staphylococcal bacteremia (20 MRSA, 2 vancomycin-intermediate S aureus, 2 methicillin-susceptible S aureus [MSSA], 2 methicillin-resistant S epidermidis). Bacteremia persisted for a median of 10 days (range, 3-23 days) on previous antimicrobial therapy. After daptomycin plus ceftaroline was started, the median time to bacteremia clearance was 2 days (range, 1-6 days). In vitro studies showed ceftaroline synergy against MRSA and enhanced MRSA killing by cathelicidin LL-37 and neutrophils. Ceftaroline also induced daptomycin binding in MSSA and MRSA to a comparable degree as nafcillin. MRSA grown in subinhibitory concentrations of ceftaroline showed attenuated virulence in a murine subcutaneous infection model.

IMPLICATIONS

Ceftaroline plus daptomycin may be an option to hasten clearance of refractory staphylococcal bacteremia. Ceftaroline offers dual benefit via synergy with both daptomycin and sensitization to innate host defense peptide cathelicidin LL37, which could attenuate virulence of the pathogen.

Environment surface sampling in 33 Washington State fire stations for methicillin-resistant and methicillin-susceptible Staphylococcus aureus

BACKGROUND

Methicillin-resistant Staphylococcus aureus (MRSA) and methicillin-susceptible S aureus (MSSA) were isolated from environment surfaces sampled from 33 Washington State fire stations.

METHODS

Samples were collected by fire personnel using commercial testing swabs. One to 6 surfaces were sampled per swab with 20 swabs per station. Biochemical tests were used to confirm MRSA and MSSA isolates. A short survey designed to collect information on cleaning procedures in the stations was included in the kits.

RESULTS

MRSA was isolated from 8.0% and MSSA from 18.5% of the 653 samples. Nineteen fire stations (58.0%) were MRSA positive, 27 stations (82.0%) were MSSA positive, and 14 stations (42.4%) were positive for both MSSA and MRSA. Three stations (9.0%) were negative for MSSA and MRSA. Twelve fire stations (37.5%) reported fire service professionals with MRSA needing medical care. Positive controls were detected at levels of >10(2) CFU/mL and negative controls were negative.

CONCLUSIONS

The kit system allowed sampling of >2,000 surfaces from fire stations across Washington State. This is the first time an estimate of the level of MRSA-infected fire personnel has been determined from multiple districts within a single state. Further work is needed to determine if these data can be extrapolated to other career-based fire stations across the country.

Dynamics of methicillin-resistant Staphylococcus aureus and methicillin-susceptible Staphylococcus aureus carriage in pig farmers: a prospective cohort study

Our purpose was to determine the dynamics of livestock-associated methicillin-resistant Staphylococcus aureus (LA-MRSA) carriage and its determinants in persons working at pig farms, in order to identify targets for interventions. This prospective cohort study surveyed 49 pig farms in the Netherlands on six sampling dates in 1 year (2010-11). Nasal and oropharyngeal swabs were collected, as well as environmental surface samples from stables and house. Of 110 pig farmers, 38% were persistent MRSA nasal carriers. The average cross-sectional MRSA prevalence was 63%. Methicillin-susceptible S. aureus (MSSA) nasal carriage was associated with fewer MRSA acquisitions (prevalence rate (PR) = 0.47, p 0.02). In multivariate analysis, an age of 40-49 years (PR = 2.13, p 0.01), a working week of ≥40 h (PR=1.89, p 0.01), giving birth assistance to sows (PR=2.26, p 0.03), removing manure of finisher pigs (PR=0.48, p 0.02), and wearing a facemask (PR = 0.13, p 0.02) were significantly related with persistent MRSA nasal carriage. A higher MRSA exposure in stables was associated with MRSA in pig farmers (p <0.0001). This study describes a very high prevalence of LA-MRSA carriage in pig farmers, reflecting extensive exposure during work. We identified the possible protective effects of MSSA carriage and of continuously wearing a facemask during work.

Comparative evaluation of the tolerability of cefazolin and nafcillin for treatment of methicillin-susceptible Staphylococcus aureus infections in the outpatient setting

BACKGROUND

Nafcillin and cefazolin are considered first-line therapy for most infections with methicillin-susceptible Staphylococcus aureus (MSSA), and recent studies have suggested similar clinical efficacy. Limited data are available on the comparative tolerability of these agents.

METHODS

In this retrospective cohort analysis of patients treated with either nafcillin or cefazolin for MSSA infection in the outpatient parenteral antimicrobial therapy clinic at Massachusetts General Hospital from 2007 to 2011, the frequency of premature antimicrobial discontinuation (PAD) and drug-emergent events (DEEs) was calculated.

RESULTS

Three hundred sixty-six and 119 patients were treated with nafcillin or cefazolin, respectively. The median anticipated duration of therapy was comparable at 28 (interquartile range [IQR], 16-37) and 29 (IQR, 24-39) days, respectively, for those treated with nafcillin and cefazolin. Fewer patients completed the prespecified treatment course with nafcillin than with cefazolin (PAD rate, 33.8% vs 6.7%; P < .0001). The hazard ratio for PAD in the nafcillin vs cefazolin groups was 2.81 (95% confidence interval [CI], 1.26-3.68). More patients in the nafcillin group developed rash (13.9% vs 4.2%; P = .002), renal dysfunction (11.4% vs 3.3%; P = .006), and liver function abnormalities (8.1% vs 1.6%; P = .01). Overall rates of DEEs per 1000 patient-days were 16.9 (95% CI, 10.4-27.3) and 4.8 (95% CI, 1.1-10.2), respectively. In 9 cases of nafcillin discontinuation, treatment was changed to cefazolin; all 9 completed treatment with no further observed DEEs.

CONCLUSIONS

Nafcillin treatment was associated with higher rates of both PAD as well as DEEs compared with cefazolin treatment. This difference in tolerability, in addition to efficacy and cost, should be considered when decisions for outpatient parenteral MSSA treatment are made.

Genetic Polymorphism of agr Locus and Antibiotic Resistance of Staphylococcus aureus at two hospitals in Pakistan

OBJECTIVE

The accessory gene regulator (agr) locus in Staphylococcus aureus (S. aureus) is a global regulator of quorum sensing and controls the production of virulence factors. This study was carried out to investigate the agr specific groups both in methicillin resistant and sensitive Staphylococcus aureus (MRSA and MSSA) and their relation with antibiotic resistance.

METHODS

A total of 90 clinical S. aureus isolates were studied from two tertiary care hospitals. The isolates were identified by standard biochemical tests. Methicillin resistance was confirmed by oxacillin and cefoxitin resistance. Multiplex PCR was used to determine the agr groups.

RESULTS

MRSA prevalence was found to be 53.3%.The agr groups' distribution in MRSA was as follows: 22 (45.8%) belonged to group I, 14 (29.1%) belonged to group III and 2 (4.1%) belonged to group II. agrIV was not detected in MRSA. For 17 isolates, the agr group was not detected.agr III isolates showed higher antibiotic resistance than agrI isolates except in case of oxacillin and linezolid.

CONCLUSIONS

Strict infection control policy and antibiotic guidelines should be adopted to control the problem of MRSA. Higher prevalence of agr I and agr III shows that they are dominant agr groups of our area.

Identification and control of a gentamicin resistant, meticillin susceptible Staphylococcus aureus outbreak on a neonatal unit

We describe the identification and control of an outbreak of gentamicin resistant, meticillin susceptible Staphylococcus aureus (GR-MSSA) on a 36-bed neonatal unit (NNU) in London. Control measures included admission and weekly screening for GR-MSSA, cohorting affected babies, environmental and staff screening, hydrogen peroxide vapour (HPV) for terminal disinfection of cohort rooms, and reinforcement of hand hygiene. Seventeen babies were affected by the outbreak strain over ten months; seven were infected and ten were asymptomatic carriers. The outbreak strain was gentamicin resistant and all isolates were indistinguishable by pulsed-field gel electrophoresis. The outbreak strains spread rapidly and were associated with a high rate of bacteraemia (35% of 17 affected patients had bacteraemia vs. 10% of 284 patients with MSSA prior to the outbreak, p=0.007). None of 113 staff members tested were colonised with GR-MSSA. GR-MSSA was recovered from 11.5% of 87 environmental surfaces in cohort rooms, 7.1% of 28 communal surfaces and 4.1% of 74 surfaces after conventional terminal disinfection. None of 64 surfaces sampled after HPV decontamination yielded GR-MSSA. Recovery of GR-MSSA from two high level sites suggested that the organism could have been transmitted via air. Occasional breakdown in hand hygiene compliance and contaminated environmental surfaces probably contributed to transmission.

Molecular epidemiology of Staphylococcus aureus in households of children with community-associated S aureus skin and soft tissue infections

OBJECTIVES

Although colonization traditionally is considered a risk factor for Staphylococcus aureus infection, the relationship between contemporary S aureus colonization and infection is not well characterized. We aimed to relate the presence of colonizing and disease-causing strains of S aureus within individuals and households.

STUDY DESIGN

In a prospective study of 163 pediatric outpatients (cases) with community-associated S aureus skin and soft tissue infections in St Louis, infection isolates were obtained from cases and colonization cultures were obtained from cases and their household contacts (n = 562). Molecular typing by repetitive sequence-based polymerase chain reaction was used to compare infecting and colonizing isolates within each case. The infecting strain from each case was compared with S aureus strains colonizing household contacts. The colonization status of cases was followed for 12 months.

RESULTS

A total of 27 distinct strain types were identified among the 1299 S aureus isolates evaluated. Between 1 and 6 distinct strain types were detected per household. A total of 110 cases (67%) were colonized at 1 or more body sites with the infecting strain. Of the 53 cases with an infecting strain that did not match a colonizing strain, 15 (28%) had 1 or more household contacts with a colonizing strain that matched the infecting strain. Intrafamilial strain-relatedness was observed in 105 families (64%).

CONCLUSION

One-third of cases were colonized with a different strain type than the strain causing the skin and soft tissue infection. Fewer than one-third of cases with discordant infecting and colonizing isolates could be linked to the strain from another household contact, suggesting acquisition from sources outside the household.

[It starts as a Lumbovertebral syndrome and ends as an acute confusional state]

Here we report the case of a 19-year-old somalian man who has been admitted to our emergency department because of an important lumbago without trauma. The physical examination on arrival showed a diffuse painful percussion of the left paraspinal muscles without neurological impairment. The laboratory exams displayed a significant elevation of the inflammatory response (CRP 154 mg/l, procalcitonin 0,05 µg/l), the blood cultures were negative and a thoracic and lumbar computed tomography (CT) was not conclusive. The unclear clinical picture led to a magnetic resonance imaging, showing the presence of an abscess in the left thoraco-lumbar paraspinal musculature with ongoing invasion of the epidural space. The clinical picture became dramatic as the patient suddenly developed a frank nuchal rigidity associated with an acute confusional state, caused by the rupture of the abscess in the meningeal space with secondary meningitis, confirmed by a lumbar puncture, where S. aureus was found.

Nanotechnology as a therapeutic tool to combat microbial resistance

Use of nanoparticles is among the most promising strategies to overcome microbial drug resistance. This review article consists of three parts. The first part discusses the epidemiology of microbial drug resistance. The second part describes mechanisms of drug resistance used by microbes. The third part explains how nanoparticles can overcome this resistance, including the following: Nitric oxide-releasing nanoparticles (NO NPs), chitosan-containing nanoparticles (chitosan NPs), and metal-containing nanoparticles all use multiple mechanisms simultaneously to combat microbes, thereby making development of resistance to these nanoparticles unlikely. Packaging multiple antimicrobial agents within the same nanoparticle also makes development of resistance unlikely. Nanoparticles can overcome existing drug resistance mechanisms, including decreased uptake and increased efflux of drug from the microbial cell, biofilm formation, and intracellular bacteria. Finally, nanoparticles can target antimicrobial agents to the site of infection, so that higher doses of drug are given at the infected site, thereby overcoming resistance.

Nanotechnology as a therapeutic tool to combat microbial resistance

Use of nanoparticles is among the most promising strategies to overcome microbial drug resistance. This review article consists of three parts. The first part discusses the epidemiology of microbial drug resistance. The second part describes mechanisms of drug resistance used by microbes. The third part explains how nanoparticles can overcome this resistance, including the following: Nitric oxide-releasing nanoparticles (NO NPs), chitosan-containing nanoparticles (chitosan NPs), and metal-containing nanoparticles all use multiple mechanisms simultaneously to combat microbes, thereby making development of resistance to these nanoparticles unlikely. Packaging multiple antimicrobial agents within the same nanoparticle also makes development of resistance unlikely. Nanoparticles can overcome existing drug resistance mechanisms, including decreased uptake and increased efflux of drug from the microbial cell, biofilm formation, and intracellular bacteria. Finally, nanoparticles can target antimicrobial agents to the site of infection, so that higher doses of drug are given at the infected site, thereby overcoming resistance.

PNA-FISH assays for early targeted bacteraemia treatment

PNA-FISH S. aureus/CNS and GNR Traffic Light assays were compared with standard culture methods for identifying bacteraemia in 156 blood cultures from 131 patients. Results correlated with final culture results in 153 cultures. Retrospective case note review revealed that earlier targeted treatment would have occurred in 10.7% of cases.

A Caenorhabditis elegans host model correlates with invasive disease caused by Staphylococcus aureus recovered during an outbreak in neonatal intensive care

BACKGROUND

Caenorhabditis elegans has previously been used as a host model to determine the virulence of clinical methicillin-resistant Staphylococcus aureus isolates. In the present study, methicillin-susceptible S aureus (MSSA) strains associated with an outbreak in a neonatal intensive care unit (NICU) were investigated using the C elegans model.

METHODS

Two distinct outbreak clones, MSSA type-C and MSSA type-G, were identified by pulsed-field gel electrophoresis in a MSSA outbreak during a seven-month period in the NICU of the Sunnybrook Health Sciences Centre (Toronto, Ontario). MSSA type-C was associated with severe infection, while type-G was associated with less invasive disease. Four representative type-C isolates, three type-G and three infant-colonized isolates unrelated to the outbreak, were sent to Calgary (Alberta), for the double-blinded virulence tests in the C elegans host model and for further molecular characterization.

RESULTS

The invasive outbreak strains (type-C) demonstrated highly nematocidal activity, the noninvasive outbreak strains (type-G) an intermediate virulence, and the outbreak-unrelated colonization isolates demonstrated avirulence or low virulence in the C elegans model, with mean killing rates of 93.0%, 61.0% and 14.4% by day 9, respectively, for these three group strains. Different group MSSA strains had their own unique genetic profiles and virulence gene profiles, but all isolates within the same group (type-C or type-G) shared identical genetic characteristics and virulence gene patterns.

CONCLUSIONS

The present blinded evaluation demonstrated that the nematocidal activities of MSSA strains correlated well with the clinical manifestation in an MSSA outbreak in the NICU, supporting C elegans as a robust host model to study the pathogenesis of S aureus.

Antibiotic susceptibility and resistance of Staphylococcus aureus isolated from fresh porcine skin xenografts: risk to recipients with thermal injury

The previous use of fresh porcine xenografts at the Prague Burn Centre had raised concerns over the transmission of zoonotic pathogens. This study examines the risk of zoonotic Staphylococcus aureus colonisation of burn patients from fresh porcine skin xenografts. Samples were collected from the nares, skin and perineum of commercial pigs (n=101) and were screened for methicillin sensitive S. aureus (MSSA) and resistant S. aureus (MRSA). The efficacy of the antibiotic wash used in decontamination of the pigskin was tested against planktonic- and biofilm-grown isolates. The spa type of each isolate was also confirmed. All pig swabs were negative for MRSA but 86% positive for MSSA. All planktonic-grown isolates of MSSA were sensitive to chloramphenicol and nitrofurantoin and 44% of isolates were resistant to streptomycin. Isolates grown as biofilm exhibited higher rates of antimicrobial resistance. Sequence analysis revealed three distinct spa types of the MRSA ST398 clonal type. This finding demonstrates the existence of a MSSA reservoir containing spa types resembling those of well-known MRSA strains. These MSSA exhibit resistance to antibiotics used for decontamination of the pigskin prior to xenograft. Amended use of procurement could allow the use of fresh pigskin xenografts to be reinstated.