Nasal Carriage and Resistance Pattern of Multidrug Resistant Staphylococcus aureus Among Healthy Children in Kashan, Iran

OUP accepted manuscript

Background

Objectives

Methods

Results

Conclusions

Molecular Epidemiology, Virulence Factors, Antibiotic Resistance and Risk Factors for Nasal Carriage of Staphylococcus aureus in A Teenage Student Population: High Prevalence of Oxacillin Susceptible MRSA Isolates

Background: Asymptomatic carriage of Staphylococcus aureus can lead to endogenous infections and cross-transmission to other individuals. Objectives: The prevalence, molecular epidemiology, antibiotic resistance, and risk factors for nasal carriage of methicillin-resistant Staphylococcus aureus (MRSA) were studied in school children in Ardabil, Iran. Methods: Totally, 510 nasal samples were collected during 2017. Isolates were identified and subjected to antimicrobial susceptibility testing, identification of oxacillin resistance, and molecular typing. Results: Totally, 13.5% of volunteers were positive for methicillin-susceptible Staphylococcus aureus (MSSA) and 17.5% colonized with mecA positive S. aureus strains, including 6.07% oxacillin-resistant MRSA (OR-MRSA) and 11.56% oxacillin-susceptible MRSA (OS-MRSA). Excluding β-lactam antibiotics, high resistance rate was observed for erythromycin (71%), tetracycline (25.8%), clindamycin (35%) in our isolates. Surprisingly, 11% of the isolates [OR-MRSA (25.8%), OS-MRSA (10.1%), and MSSA (5.7%) isolates] were resistant to mupirocin. Moreover, 18 (58%), 29 (49%), and 29 (42%) of OR-MRSA, OS-MRSA, and MSSA isolates were multidrug-resistant (MDR), respectively. Overall, 97.48% of isolates carried ≥ 3 toxin encoding genes. The pvl gene was found in 46 (29%) isolates. In comparison, 25.50% of MRSA (9.60% OR-MRSA and 34% OS-MRSA) and 33% of MSSA isolates carried pvl gene. SCCmec type IV had the highest rate among OR-MRSA (87%) and OS-MRSA (74.5%) isolates, which indicates CA-MRSA phenotype. Eleven and 21 spa types were identified in OR-MRSA, and OS-MRSA isolates, respectively. The most common spa types were t11332 (14.3%) and t012 (11.4%) in OS-MRSA isolates. ERIC-PCR revealed high genetic diversity among isolates. The number of students in classroom and incomplete antibiotic course were associated with OS-MRSA nasal carriage. Conclusions: This study showed a high proportion of MDR CA-MRSA nasal carriage among Iranian healthy school children community.

Nasal Carriage and Antibiotic Resistance Pattern of Methicillin-Resistant Staphylococcus aureus Isolates from Clinical Staff of a Referral Hospital, Zabol, Iran

Introduction: Staphylococcus aureus is known as the causative agent of various infections in humans, and the nasal cavity is the main anatomical site for storing and spreading this pathogen in health care workers (HCWs) in hospital settings. Methicillin-resistant S. aureus (MRSA) strains are resistant to many antibiotics. The aim of this study was to investigate the prevalence and antibiotic resistance patterns of S. aureus strains isolated from the nasal carriage of HCWs in a referral hospital in Zabol. Methods: A total of 277 HCWs of Amir-Al-Momenin hospital of Zabol participated voluntarily in this study from March to September 2017. Demographic information was collected using questionnaire. Bacterial isolates were collected from anterior nasal canal using cotton swabs. MRSA isolates were detected by Oxacillin Screen agar and polymerase chain reaction (PCR). Antibiotic resistance was assessed by the disk-diffusion method.Results: In total, 10.8% of HCWs were carriers of S. aureus and 46.7% of the isolates were found to be MRSA. Laboratory staffs were the most frequently colonized HCWs. All the isolates were susceptible to vancomycin, teicoplanin and gentamicin. The highest resistance rate (64.3%) of MRSA isolates was observed against erythromycin.Conclusion: Our findings showed that gentamycin and rifampin might be useful to eradicate S.aureus. Regular screening of HCWs and assessment of antibiotic resistance profile are essential to prevent MRSA dissemination in hospitals.

Methicillin-resistant Staphylococcus aureus (MRSA) in Iran: A systematic review and meta-analysis

INTRODUCTION

Methicillin-resistant Staphylococcus aureus (MRSA) is among the most prevalent pathogens causing healthcare-associated infections. Accurate and updated data describing the epidemiology of MRSA are crucial for the development of national policies to control MRSA infection in each country. This study aimed to estimate the prevalence of MRSA in different parts of Iran.

METHODS

Several databases, including MEDLINE, Embase, Web of Science and Scientific Information Database (http://www.sid.ir), were searched from 1 January 2000 to 31 March 2016 to identify studies addressing the frequency or prevalence of MRSA in Iran. Comprehensive Meta-Analysis software v.2.2 was used to analyse the data.

RESULTS

Of the 725 records identified from the databases, 31 studies fulfilled the eligibility criteria. The analyses showed that the frequency of MRSA infections was 43.0% (95% confidence interval 36.3-50.0%) among confirmed S. aureus isolates. Further stratified analyses indicated that the prevalence of MRSA was higher in studies performed after the year 2000.

CONCLUSIONS

Since a high rate of MRSA infections was seen in this analysis, regular surveillance of hospital-associated infections, monitoring of antibiotic sensitivity patterns, and formulation of definite antibiotic policy may facilitate more accurate action for the prevention and control of MRSA.

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.

Distribution of Genes Encoding Resistance to Macrolides Among Staphylococci Isolated From the Nasal Cavity of Hospital Employees in Khorramabad, Iran

Background

Epidemiological data on antibiotic susceptibility of Staphylococcus strains isolated from nasal carriers in each region can be helpful to select appropriate drugs to eradicate carriage states, control nosocomial infections and also treat patients.

Objectives

The current study aimed to investigate the antibiotic resistance profile and the molecular prevalence of the ermA, ermB, ermC and msrA genes among Staphylococcus strains isolated from the anterior nares of hospital employees.

Patients and Methods

In this cross-sectional study, a total of 100 Staphylococcus isolates, 51 Staphylococcus aureus, 49 coagulase-negative staphylococci (CoNS) were isolated from the anterior nares of hospital employees in Khorramabad, Iran. Susceptibility pattern to macrolide antibiotics were determined using the disk diffusion method. The polymerase chain reaction (PCR) assay was applied to determine the major erythromycin-resistant genes (ermA, ermB, ermC and msrA).

Results

Fifty-three (53%) isolates were simultaneously resistant to erythromycin, azithromycin and clarithromycin (cross-resistance); while 8 (8%) isolates had variable macrolide susceptibility pattern. Among the S. aureus isolates, the difference in prevalence of resistance to erythromycin between males and females was significant (P = 0.011). The frequency of ermA, ermB, ermC, and msrA genes were 3%, 5%, 33% and 20%, respectively. It was also found that out of 53 isolates resistant to erythromycin, 44 (83%) isolates (eight S. aureus and thirty-six CoNS strains) carried at least one of the four tested genes. Eight (8%) isolates had intermediate phenotype to erythromycin, in which 4 (50%) isolates carried ermB or ermC genes. In addition, out of 39 erythromycin-susceptible isolates, 3 (7.7%) isolates were positive for ermB or ermC genes.

Conclusions

No entire association was found between genotype and phenotype methods to detect macrolides-resistant isolates. In addition, distribution of genetically erythromycin-resistant isolates is geographically different among staphylococci. It is recommend removing S. aureus from nasal carriers by proved approaches such as local or systemic administration of effective antibiotics or bacterial interference.

Genotyping of coa and aroA Genes of Methicillin-Resistant Staphylococcus aureus Strains Isolated From Nasal Samples in Western Iran

Background:

Methicillin-resistant Staphylococcus aureus (MRSA) is a bacterial pathogen frequently isolated in both hospital and community environments. Methicillin-resistant Staphylococcus aureus is considered a major nosocomial pathogen that causes severe morbidity and mortality.

Objectives:

The main objective of this study was to determine the genotypes of MRSA strains isolated from the nares of hospitalized and community patients in Kermanshah Hospital, western Iran, by PCR-restriction fragment length polymorphism (PCR-RFLP).

Materials and Methods:

Of 1387 patients, 1217 patients were screened for more than 48 hours after admission in hospital wards and 170 patients were screened in the hemodialysis unit of Kermanshah Hospital, which is the largest hospital in western Iran. S. aureus was identified by standard biochemical tests, including colonial morphology, production of coagulase, and DNase and the API20 Staph test. Methicillin-resistant Staphylococcus aureus was identified by the Oxacillin strip test.

Results:

In total, 258 S. aureus isolates were recovered from 1387 samples, of which 96 isolates were MRSA, 82 were hospital acquired, and 14 were community acquired. Digestion of the aro A gene revealed only one distinctive RFLP pattern in the 258 isolates.

Conclusions:

Methicillin-resistant Staphylococcus aureus is an increasingly common cause of nosocomial infections. Our results are in agreement with those of other studies reporting that a few specialized clones are responsible for most cases of MRSA nasal carriage. In this study, MRSA strains isolated from different wards of hospital were closely related when analyzed by coagulase gene typing. Identifying patients colonized with MRSA during hospitalization and rapidly typing them with these methods may facilitate detection of outbreaks and prevention of the spread of organisms in hospitals.

Staphylococcus aureus Isolates Carrying Panton-Valentine Leucocidin Genes: Their Frequency, Antimicrobial Patterns, and Association With Infectious Disease in Shahrekord City, Southwest Iran

Background:

A diversity of virulence factors work together to create the pathogenicity of Staphylococcus aureus. These factors include cell surface components that promote adherence to surfaces as well as exoproteins such as Panton-Valentine leukocidin (PVL), encoded by the luk-PV genes, that invade or bypass the immune system and are toxic to the host, thereby enhancing the severity of infections caused by methicillin-resistant Staphylococcus aureus (MRSA).

Objectives:

The aim of this study was to determine the frequency of PVL-positive MRSA strains by real-time PCR and their antibiotic susceptibility patterns by phenotypic test.

Materials and Methods:

In total, 284 Staphylococcus isolates, identified by phenotypic methods from clinical samples of Shahrekord University Hospitals, Shahrekord, Iran, were tested for nuc, mecA, and PVL genes by TaqMan real-time PCR. The antibiotic susceptibility patterns of PVL-containing MRSA strains were determined via the disk diffusion method.

Results:

In total, 196 isolates (69%) were nuc positive (i.e., S. aureus); of those isolates, 96 (49%) were mecA positive (MRSA). Eighteen (18.8%) of the 96 MRSA positive and 3 (3%) of the 100 methicillin-susceptible Staphylococcus aureus (MSSA) strains were PVL positive. PVL-positive MRSA strains were mostly recovered from tracheal specimens. Eight PVL-positive MRSA strains were resistant to all the tested antibiotics except vancomycin. A significant correlation (P = 0.001) was found between the mecA positivity and the presence of luk-PV genes.

Conclusions:

Community acquired (CA)-MRSA is becoming a public health concern in many parts of the world, including Asian countries. The variable prevalence of luk-PV-positive MRSA isolates in different regions and their rather high frequency in pneumonia necessitate the application of rapid diagnostic methods such as real-time PCR to improve treatment effectiveness.

Bactericidal and Antibiotic Synergistic Effect of Nanosilver Against Methicillin-Resistant Staphylococcus aureus

Background:

Methicillin-Resistant Staphylococcus aureus (MRSA) are bacteria responsible for several difficult-to-treat infections in humans. These strains have developed, through the process of natural selection. Infections by MRSA are more difficult to treat with standard types of antibiotics and thus more dangerous to human health.

Objectives:

The aim of this study was to evaluate the bactericidal and antibiotic synergistic effect of silver nanoparticles (Ag-NPs) against MRSA.

Materials and Methods:

Methicillin-Resistant Staphylococcus aureus strains were isolated from clinical samples and identified, and their susceptibility was tested using the MicroScan® WalkAway-96® SI System. minimum inhibitory concentration (MIC) was determined by a microdilution method. Time kill assay was performed by exposing the MRSA isolates to different concentrations of Ag-NPs and monitoring bacterial growth, by measuring optical density at 600 nm. Tissue culture plate was used for determination of the efficacy of Ag-NPs and their combination with antibiotics in the elimination of formed biofilm.

Results:

The MIC value of Ag-NPs against MRSA was 100 μg/mL. Methicillin-Resistant Staphylococcus aureus cells were treated with 50, 100 and 200 µg/mL of Ag-NPs and inhibited bacterial growth so that after four hours, almost all treated MRSA cells were dead. All combinations showed effectiveness against MRSA. It was observed that MRSA did not show inhibition zones with ampicillin alone.

Conclusions:

Silver Nanoparticles have high therapeutic activity against MRSA, thus can be suggested as an alternative or adjuvant with antibiotics for MRSA treatment. Further studies are required to understand the synergistic effect of Ag-NPs combinations and to assess the safety and efficacy of new antibiotic-Ag-NPs combinations.

Nasal Carriage of Staphylococcus aureus : Frequency and Antibiotic Resistance in Healthy Ruminants

Background:

Staphylococcus aureus is a significant pathogen that can colonize the nares of different animals, causing a wide range of infections in various hosts.

Objectives:

We intended to determine the prevalence of S. aureus in the nasal cavity of healthy ruminants and also to investigate the presence of antibiotic resistance genes.

Materials and Methods:

In the present study, healthy cattle (n = 79), sheep (n = 78) and goats (n = 44) were screened for nasal carriage of S. aureus by the Polymerase Chain Reaction (PCR). Staphylococcus aureus isolates were further assessed for the presence of blaZ (encoding penicillin resistance), mecA (encoding methicillin resistance), tetK and tetM (encoding tetracycline resistance), and ermA and ermC (encoding macrolide-lincosamide-streptogramin B resistance) genes.

Results:

The proportion of S. aureus-positive nasal swabs from cattle, sheep and goats were four (5.06%), 11 (14.1%) and 11 isolates (25%), respectively. The blaZ gene was detected in 20 out of 26 S. aureus isolates (76.9%), including four cattle (100%), nine sheep (81.8%) and seven goats (63.6%). Two of the four cattle isolates possessing the blaZ gene also had the tetK gene. Of the nine sheep isolates harboring the blaZ gene, one possessed the mecA and tetK genes together. Of the seven goat isolates with blaZ gene, one harbored the tetM gene. None of the S. aureus isolates were positive for the ermA and ermC genes.

Conclusions:

In contrast to cattle, S. aureus is frequently present in the nose of sheep and goats, which may represent the primary reservoir of S. aureus in small ruminant flocks. This study also showed that nasal isolates of S. aureus from healthy ruminants might be a potential reservoir of antimicrobial-resistance.

Analysis of Healing Effect of Alginate Sulfate Hydrogel Dressing Containing Antimicrobial Peptide on Wound Infection Caused by Methicillin-Resistant Staphylococcus aureus

BACKGROUND

Wound infections caused by methicillin-resistant Staphylococcus aureus are a health problem worldwide; therefore, it is necessary to develop new antimicrobial compounds. Considering broad-spectrum antimicrobial activity and low probability of drug resistance to peptides, applications these peptides are being studied extensively.

OBJECTIVES

In this study, to control drug release over time, an alginate sulfate-based hydrogel impregnated with the CM11 peptide as the antimicrobial agent was developed, and its healing effects were tested on skin infections caused by methicillin-resistant S. aureus strains in a mouse model.

MATERIALS AND METHODS

Minimum inhibitory and minimum bactericidal concentrations of the CM11 peptide and alginate hydrogel in combination with the peptide were determined. Forty mice were divided into 4 groups: 1 group as a negative control (without treatment; however, 5 mice received hydrogel dressing without peptide), 1 group as a positive control (2% mupirocin treatment), and 2 groups as test groups. To establish skin infection, 200 μL of bacterial suspension with 3 × 10(8) CFU/mL concentration was subcutaneously injected in the scapular region of the mice. On the basis of the in vitro minimal bactericidal concentration of the alginate hydrogel containing peptide for 15 clinical isolates, hydrogel containing 128 mg/L of peptide was used for wound dressing over an 8-day period.

RESULTS

The highest and lowest numbers of wounds were observed on day 2 in the negative and positive control groups, respectively. During the 8-day period, the positive control and hydrogel containing peptide treatment groups showed similar levels of wound healing.

CONCLUSIONS

This study showed that compared to standard drug treatment, treatment with hydrogel containing peptide had substantial antibacterial effects on S. aureus wound infections in mice.