Differences in Staphylococcus aureus nasal carriage and molecular characteristics among community residents and healthcare workers at Sun Yat-Sen University, Guangzhou, Southern China

Nasal Staphylococcus aureus Carriage and Antimicrobial Resistance Profiles Among Community-Dwelling Adults in Jiangsu, China

INTRODUCTION

Persistent nasal carriage has been associated with Staphylococcus aureus infection. Previous S. aureus studies in Asia have primarily focused on clinical patients, providing limited information on persistent nasal carriage among the general adult population.

METHODS

This study examined 143 healthy adults in a community in Jiangsu, China. Nasal swab samples were collected 10 times. The colonization status was identified using SPA typing. We also determined antimicrobial susceptibility, genotype, and genomic characteristics of S. aureus.

RESULTS

The prevalence of S. aureus nasal carriage among the community individuals was on average 16.78%. The carriage rates of methicillin-resistant S. aureus and multidrug-resistant S. aureus were 6.29% and 7.69%, respectively. We identified 8.39% persistent carriers, 39.16% intermittent carriers, and 52.45% noncarriers. Furthermore, family members displayed concordance in terms of genotype and genomic characteristics.

CONCLUSION

Persistent nasal sampling captured intermittent carriers that were missed during short-term sampling, thus highlighting the necessity for regular community testing. SPA typing can serve as a rapid method for determining S. aureus colonization. The potential for intrafamilial transmission of S. aureus is evident, with persistent carriers being the most probable source of infection.

To screen or not to screen medical students for carriage of multidrug-resistant pathogens?

BACKGROUND

The carriage of multidrug-resistant (MDR) pathogens in medical students has not been studied extensively, despite the fact that they are in contact with patients and exposed to a hospital environment.

AIM

To investigate the intestinal and nasal carriage of MDR pathogens among medical students and its association with their lifestyle and demographic data.

METHODS

In 2021, first- and final-year medical students were invited to the study. Two rectal swabs were used for detection of extended-spectrum β-lactamase (ESBL)-producing, colistin-, tigecycline- or carbapenem-resistant Gram-negative bacteria and vancomycin-resistant enterococci. Nasal swab was used for Staphylococcus aureus culture. S. aureus isolates were characterized by spa typing; Gram-negative resistant isolates and meticillin-resistant S. aureus (MRSA) were subjected to whole-genome short and/or long sequencing.

FINDINGS

From 178 students, 80 (44.9%) showed nasal carriage of S. aureus; two isolates were MRSA. In rectal swabs, seven ESBL-producing strains were detected. Sixteen students were colonized by colistin-resistant bacteria, three isolates carried the mcr-1 gene (1.7%). The mcr-9 (10.7%, 19/178) and mcr-10 (2.2%, 4/178) genes were detected by quantitative polymerase chain reaction, but only two colistin-susceptible mcr-10-positive isolates were cultured. The S. aureus nasal carriage was negatively associated with antibiotic and probiotic consumption. S. aureus and colistin-resistant bacteria were detected more frequently among students in contact with livestock.

CONCLUSION

Medical students can be colonized by (multi)drug-resistant bacteria with no difference between first- and final-year students. The participation of students in self-screening increases their awareness of possible colonization by resistant strains and their potential transmission due to poor hand hygiene.

Unveiling the Relevance of the Oral Cavity as a Staphylococcus aureus Colonization Site and Potential Source of Antimicrobial Resistance

Staphylococcus aureus is both a human commensal and a pathogen, that causes serious nosocomial and community-acquired infections. Despite nostrils being considered its preferred host habitat, the oral cavity has been demonstrated to be an ideal starting point for auto-infection and transmission. The antibiotic resistance assessment of S. aureus is a priority and is often reported in clinical settings. This study aimed to explore the prevalence and antimicrobial susceptibility of S. aureus in the oral and nasal cavities of healthy individuals. The participants (n = 101) were subjected to a demographic and clinical background survey, a caries evaluation, and to oral and nasal swabbing. Swabs were cultured in differential/selective media and S. aureus isolates were identified (MALDI-TOF MS) and tested for antibiotic susceptibility (EUCAST/CLSI). Similar S. aureus prevalence was found exclusively on nasal (13.9%) or oral (12.0%) habitats, whereas 9.9% of the population were simultaneous nasal and oral carriers. In oro-nasal cavities, similar antibiotic resistance rates (83.3-81.5%), including MDR (20.8-29.6%), were observed. Notably, 60% (6/10) of the simultaneous nasal and oral carriers exhibited different antibiotic resistance profiles between cavities. This study demonstrates the relevance of the oral cavity as an independent colonization site for S. aureus and as a potential source of antimicrobial resistance, a role which has been widely neglected so far.

The association between antibiotics and community-associated Staphylococcus aureus colonization in the United States population: Analysis of the National Health and Nutrition Examination Survey (NHANES)

Staphylococcus aureus nasal colonization is a seriously opportunistic infection. However, there is a lack of research of relationship between antibiotics and S aureus colonization in the general population. Through a cross-sectional investigation, this study intends to establish the parameters related to S aureus nasal colonization, specifically the function antibiotics play in colonization. The key information from 2001 to 2004 was abstracted from National Health and Nutrition Examination Survey (NHANES), including information on general demographics, health care status, antibiotic prescription, diabetes, alcohol consumption, and tobacco smoke exposure. The participants colonized with methicillin-susceptible S aureus (MSSA), or methicillin-resistant S aureus (MRSA) were defined as the case group, and the control group was subjects without positive S aureus colonization. Univariate and multivariate logistic regression models were used to identify the variables associated with MSSA and MRSA colonization. The records of 18,607 individuals were included, involving 13,205 cases without S aureus colonization, 5195 cases with MSSA, and 207 cases with MRSA. In the multivariate logistic regression analysis, the risk of MSSA colonization was significantly reduced with fluoroquinolone use (75% risk reduction, P = .02), sulfonamide use (98% risk reduction, P < .01), tetracycline use (81% risk reduction, P < .01) and antibiotic combination therapy (risk reduction 76%, P < .01). Female, race and total household size were strongly associated with MSSA carriage. On the other hand, regarding MRSA colonization, fluoroquinolone use, long-term care, and former smoker were positively associated with MRSA colonization, while high income was negatively associated with MRSA colonization. More proper use of broad-spectrum antibiotics contributes to reducing MSSA colonization. Former smokers should also practice better personal hygiene to limit the possibility of MRSA colonization.

Prevalence and genetic lineages of Staphylococcus aureus nasal colonization and urinary tract infection among people living with HIV/AIDS in Nigeria: A systematic review

To provide an empirical insight on Staphylococcus aureus (S. aureus) nasal colonization and urinary tract infection (UTI) among people living with HIV/AIDS (PLWHA) in Nigeria, a quantitative synthesis and systematic review were executed. A comprehensive bibliometric search was conducted for published articles using the keywords 'nasal S. aureus carriage', 'Urinary S. aureus', 'nasal MRSA', 'staphylococci-HIV coinfection', 'urinary MRSA' and 'all states of Nigeria'. Eligible studies and the number of subjects (n) were analysed according to the PRISMA criteria. Out of the 79 examined studies, only 6 (n=1181) and 6 (n= 1350) on nasal and urine samples, respectively, were eligible. The pooled prevalence of nasal carriage and UTI of S. aureus were 29.6% and 6.8%, respectively. However, the pooled nasal MRSA carriage was 13.4%. The pooled prevalence of luk-F/S-PV-carrying S. aureus among nasal samples was 13.0%. Molecular typing from 3 studies showed MRSA-ST8-t064 and MSSA-ST15-t084 as the predominant genetic lineages. The S. aureus isolates from both sample types had the highest (>50%) resistance to penicillin, sulfamethoxazole-trimethoprim, erythromycin, and tetracycline. Multi-drug resistance was not significantly higher among S. aureus isolates from urine than nasal samples (60% versus 40.0% of eligible studies) (p= 0.5271). A moderate and high pooled prevalence of genetically diverse MRSA and luk-F/S-PV-carrying S. aureus were obtained from PLWHA, respectively. These findings emphasize the importance of routine screening for MRSA among PLWHA in Nigeria and other HIV endemic countries.

Nasal Carriage of Methicillin-Resistant Staphylococcus aureus among Healthcare Workers in a Tertiary Care Hospital, Kathmandu, Nepal

Introduction

Methicillin-resistant Staphylococcus aureus (MRSA) is one of the most common causes of nosocomial infections. One of the potential risk factors for nosocomial staphylococcal infections is colonization of the anterior nares of healthcare workers (HCWs). Our study aimed to determine the rate of nasal carriage MRSA among HCWs at Manmohan Memorial Medical College and Teaching Hospital, Kathmandu.

Methods

Two hundred and thirty-two nasal swabs were collected from HCWs of Manmohan Memorial Medical College and Teaching Hospital, Kathmandu, Nepal, within six months (February 2018-July 2018). Nasal swabs were cultured, and S. aureus isolates were subjected to the antimicrobial susceptibility test by the modified Kirby-Bauer disc diffusion method. MRSA and iMLSB (inducible macrolide lincosamide streptogramin B) resistance was screened using the cefoxitin disc (30 μg) and D-test (clindamycin and erythromycin sensitivity pattern), respectively, following CLSI (Clinical and Laboratory Standard Institute) guidelines. Risk factors for MRSA colonization were determined using the chi-square test considering the p value ˂0.05 as significant.

Results

A total of 34/232 (14.7%) S. aureus were isolated, out of which 12 (35.3%) were MRSA. The overall rate of nasal carriage MRSA among HCWs was 5.2% (12/232). Colonization of MRSA was higher in males (8.7%) than in females (4.3%). MRSA colonization was found to be at peak among the doctors (11.4%). HCWs of the postoperative ward were colonized highest (18.2%). All MRSA isolates were sensitive to linezolid and tetracycline. iMLSB resistance was shown by 7(20.6%) of the isolates. MRSA strains showed higher iMLSB resistance accounting for 33.3% (4/12) in comparison to methicillin-susceptible strains with 13.6% (3/22). Smoking was found to be significantly associated with MRSA colonization (p=0.004).

Conclusion

Rate of nasal carriage MRSA is high among HCWs and hence needs special attention to prevent HCW-associated infections that may result due to nasal colonization.

Prevalence of methicillin-resistant Staphylococcus aureus colonization among healthcare workers at a tertiary care hospital in northeastern Brazil

BACKGROUND

Staphylococcus aureus is a human pathogen of clinical importance related to a variety of infections.

AIM

The objective of this study was to analyze the molecular and epidemiological characteristics of S. aureus obtained from healthcare professionals (HCP) of a hospital in southwestern Bahia, Brazil.

METHODS

Samples were collected from hands, nasal cavity, and laboratory coats of 80 HCP. The bacterial isolates recovered from 240 samples were identified as S. aureus, and then analyzed for their antimicrobial resistance profile, genotypic characterization, and pathogenicity.

FINDINGS

178 isolates were identified as S. aureus, being mostly isolated from the nasal cavity. Thirty isolates (16.8%) were characterized as MRSA. The virulence gene frequency varied according to isolate source. All virulence genes were identified in at least one hand isolate. Isolates from laboratory coats did not show seb and pvl. Isolates from the nasal cavity did not exhibit pvl. The SCCmec type I was identified in 56.7% of MRSA isolates. Among MRSA isolates, 14 PFGE pulsotypes were characterized, with profile A being predominant (nine isolates). Clonal complexes CC5, CC45, and CC398 were found. MRSA isolates induced cytokine gene expression in macrophages, with IL-10 and IL-17 being expressed more often.

CONCLUSION

We found a high colonization rate for S. aureus among HCP. Moreover, we observed that MRSA strains presented different virulence factors and could induce cytokine gene expression, indicating an urgent need to control colonization rates of HCP by MRSA isolates in order to protect hospital patients and the general public.

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

INTRODUCTION

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Prevalence, Characterization, and Drug Resistance of Staphylococcus Aureus in Feces From Pediatric Patients in Guangzhou, China

Background: Staphylococcus aureus (S. aureus) is a major pathogen of human infections. Its fecal carriage serves as a risk factor for nosocomial transmission and disease development. However, the rate of S. aureus fecal carriage among Chinese children has not yet been reported. Therefore, we sought to investigate the prevalence, characterization, and drug resistance of S. aureus isolated from pediatric patients' feces in Southern China. Methods: Fecal samples (2059) from pediatric patients in three centers in Guangzhou were cultured. From which, 412 S. aureus isolates were identified via selective mediums and automated VITEK Mass Spectrometer analysis. Antibiotic susceptibility was determined and DNA sequencing of seven housekeeping genes were used for multilocus sequence typing analysis. Results: The fecal carriage rates were 20.0% for S. aureus and 4.5% for methicillin-resistant S. aureus (MRSA). Moreover, S. aureus fecal carriage was positively correlated with outpatient status and gastroenteritis diagnosis. Moreover, age-related patterns were observed with respect to prevalence of S. aureus. Besides, a total of 76 sequence types (STs) were identified, including 25 newly assigned STs and 28 clonal complexes (CCs). ST188, ST6, and ST15 were the most prevalent methicillin-sensitive S. aureus (MSSA) clones, while ST59 and ST45 were the major MRSA clones. S. aureus isolates also exhibited high rates of penicillin (84.2%), erythromycin (38.8%), and clindamycin (35.9%) resistance. Specifically, all ST30 and ST338 isolates were resistant to erythromycin and clindamycin, 61% of ST7 were resistant to tetracycline, and 84% of ST45 exhibited resistance and intermediate resistance to rifampicin. Also, CC59 (ST338 and ST59) and CC45 exhibited different antibiotic resistance patterns. Conclusion: These results demonstrate the colonization dynamics and molecular epidemiology of S. aureus in child feces in Southern China. Further, they suggest an urgency for strengthening the surveillance programs in China and provide important information for the prevention and treatment of S. aureus infection.

Prevalence, risk factors, phenotypic and molecular characteristics for Staphylococcus aureus carriage in community-based drug users in Guangzhou, China

Background

Staphylococcus aureus (S. aureus), particularly methicillin-resistant Staphylococcus aureus (MRSA), remains the predominant cause of infections in drug users. This cross-sectional study aims to elucidate the prevalence, risk factors, phenotypic and molecular characteristics of S. aureus carriage among community-based drug users.

Methods

All eligible drug users, with both injection and non-injection route of drug administration, were asked to complete questionnaires and collect nasal swabs by trained personal during the period between May and December 2017 in Guangzhou, China. Swabs were processed for identification of S. aureus. Antimicrobial susceptibility test and polymerase chain reaction assays were used to detect phenotypic and molecular characteristics for identified isolates. Univariate and multivariate logistic regression analyses were used to assess risk factors for S. aureus carriage.

Results

Overall, 353 drug users were included in the study and the prevalence of S. aureus carriage was 15.01% (53/353). The prevalence of MRSA carriage was 6.80% (24/353). Cohabitation was a risk factor for S. aureus (adjusted OR = 8.80, 95% CI: 1.89–40.99). The proportion of multidrug resistance was 54.72% for S. aureus isolates and most of these isolates were resistant to penicillin, erythromycin and clindamycin. Seventeen MRSA isolates were multidrug resistant. The results of clonal complexes (CCs) and sequence types (STs) for S. aureus were diverse. The three predominant types for CCs were CC5 (64.15%, 34/53), CC59 (11.32%, 6/53), and CC7 (7.55%, 4/53); and for STs were ST188 (20.75%, 11/53), ST5 (11.32%, 6/53), and ST59 (11.32%, 6/53).

Conclusion

The prevalence of S. aureus nasal carriage was lower while the prevalence of MRSA carriage was moderate compared to previous studies. Phenotypic and molecular characteristics of S. aureus isolates, particularly MRSA isolates, revealed high proportions of antibiotic resistance, indicating the existence of cross-circulation, and implying high opportunity of virulence-related diseases. Decolonization and antibiotic stewardship might be implemented for drug users with MRSA carriage.

Prevalence of methicillin-resistant Staphylococcus aureus in healthy Chinese population: A system review and meta-analysis

Objective

To comprehensively determine the prevalence of MRSA in healthy Chinese population, the influencing factors of MRSA colonization and its antibiotic resistance.

Methods

Articles that studied prevalence or influencing factors of MRSA carriage in healthy Chinese population were retrieved from PubMed, Ovid database, three Chinese electronic databases. The pooled prevalence of MRSA, its antibiotic resistance and influencing factors were analyzed by STATA12.0.

Results

37 studies were included. The pooled prevalence of MRSA was 21.2% (95% CI: 18.5%-23.9%), and the prevalence of S.aureus was 15% (95% CI: 10%-19%), with a significant heterogeneity (MRSA: I² = 97.6%, P<0.001; S.aureus: I² = 98.4%, P < 0.001). In subgroup analysis, the pooled prevalence of MRSA was 28% (95%CI: 10%-51%) for Livestock-related workers, 18% (95%CI: 11%-26%) for children, 20% (95%CI: 12%-29%) for healthcare workers, 7% (95%CI: 3%-13%) for community residents. The prevalence of MRSA in studies with oxacillin disk diffusion method (28%, 95%CI: 21%-35%) seemed higher than that with the mecA gene method(12%, 95%CI: 7%-19%). MRSA in studies conducted in Taiwan was more common than in Mainland China and Hong Kong. Similar results were found in meta-regression. Influencing factors for MRSA colonization were noted in seven eligible studies, they included younger age (OR: 3.54, 95% CI: 2.38–5.26; OR: 2.24, 95% CI: 1.73–2.9), attending day care centers (DCCs) (OR: 1.95, 95% CI: 1.4–2.72; OR: 1.53, 95% CI: 1.2–1.95), flu vaccination (OR:1.73, 95% CI: 1.28–2.35), using antibiotics within the past year (OR: 2.05, 95% CI:1.35–3.11), residing in northern Taiwan (OR: 1.45, 95% CI: 1.19–1.77), regular visits to health care facility (OR: 23.83, 95% CI: 2.72–209.01), household member working in health care facility (OR: 8.98, 95% CI:1.4–55.63), and contact with livestock (OR: 6.31, 95% CI: 3.44–11.57). Moreover, MRSA was found to be highly resistant to penicillin, ampicillin, erythromycin, and clindamycin, with a pooled resistance ratio of 100, 93, 88, and 75%, respectively. However, no resistance were noted to vancomycin.

Conclusion

The pooled prevalence of MRSA was considerably high in health Chinese population. Additionally, these strains showed extreme resistance to penicillin, ampicillin, erythromycin and clindamycin. Public MRSA protection measures and the surveillance of MRSA should be strengthened to reduce the spread of MRSA among hospitals, communities, and livestock.

Prevalence and Genetic Characteristics of Methicillin-Resistant Staphylococcus aureus and Coagulase-Negative Staphylococci Isolated from Oral Cavity of Healthy Children in Japan

Prevalence and genetic characteristics of methicillin-resistant Staphylococcus aureus (MRSA) and coagulase-negative staphylococci in oral cavity of healthy children were studied in Hokkaido, northern main island of Japan. From saliva of 526 children, a total of 248 staphylococcal isolates comprising S. aureus (n = 143), S. epidermidis (n = 84), S. warneri (n = 13), S. haemolyticus (n = 5), S. hominis (n = 2), and S. intermedius (n = 1) were recovered. Presence of mecA was confirmed in 6.3% of S. aureus, 50% of S. epidermidis, and 7.7% in S. warneri. SCCmec was mostly classified into type IV, and ACME (arginine catabolic mobile element)-arcA was detected in S. epidermidis (23.8%) and S. intermedius. Nine MRSA isolates belonged to staphylocoagulase gene (coa) type Ia, IIa, IIIa, VIIb/sequence type 1 (ST1), ST5, ST8, ST89, ST120, and were negative for PVL (Panton-Valentine leukocidin) genes. These isolates included two clones of emerging community-acquired MRSA (CA-MRSA) that had been described recently in Japan: ST5/SCCmec IVc, which resembles the "Pediatric clone," and ST8/SCCmec IVl belonging to coa-IIIa/agr-I with sasL gene, designated "CA-MRSA/J" clone. Various enterotoxin genes were found in all the MRSA and some methicillin-susceptible S. aureus (MSSA) isolates examined, while tst-1 was detected in four MRSA isolates. Notably, a variant of elastin-binding protein gene (ebpS-v) was identified in ST120 MRSA and ST45 MSSA isolates, and exfoliative toxin D gene (etd) was detected in an MSSA isolate. The present study revealed the presence of MRSA, including the novel CA-MRSA clones, and high prevalence of methicillin-resistant S. epidermidis in oral cavity of healthy children in Japan.

Prevalence and risk factors of community-associated methicillin-resistant Staphylococcus aureus carriage in Asia-Pacific region from 2000 to 2016: a systematic review and meta-analysis

OBJECTIVE

Community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA) is an emerging global public health threat. In response to a highlighted strategic priority of the World Health Organization Global Action Plan on Antimicrobial Resistance, to "strengthen the knowledge and evidence base through surveillance and research", we synthesized published articles to estimate CA-MRSA carriage prevalence in the Asia-Pacific region.

METHODS

A systematic review was conducted following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines (PROSPERO CRD:42017067399). We searched MEDLINE, EMBASE, and PubMed for articles published from 1 January 2000 to 19 May 2017, which reported CA-MRSA carriage (defined as either colonization or infection) in Asia-Pacific region from 2000 to 2016. Studies were stratified according to settings (community or hospital where CA-MRSA was isolated) and study populations (general public or subpopulations with specified characteristics). Ranges of CA-MRSA carriage prevalence were reported for study groups.

RESULTS

In total, 152 studies were identified. Large diversity was observed among studies in most study groups. In community-level studies, the CA-MRSA carriage prevalence among the general public ranged from 0% to 23.5%, whereas that ranged from 0.7% to 10.4% in hospital settings. From community-level studies, countries with the highest prevalence were India (16.5%-23.5%), followed by Vietnam (7.9%) and Taiwan (3.5%-3.8%). Children aged ≤6 (range: 0.5%-40.3%) and household members of CA-MRSA carriers (range: 13.0%-26.4%) are subgroups without specific health conditions but with much higher CA-MRSA carriage when compared to the general population.

CONCLUSION

Our CA-MRSA prevalence estimates serve as the baseline for future national and international surveillance. The ranges of prevalence and characteristics associated with CA-MRSA carriage can inform health authorities to formulate infection control policies for high-risk subgroups. Future studies should explore the heterogeneities in CA-MRSA carriage prevalence among subgroups and countries to clarify the predominant transmission mechanisms in Asia-Pacific and other regions.

Staphylococcus aureus Nasal Colonization: An Update on Mechanisms, Epidemiology, Risk Factors, and Subsequent Infections

Up to 30% of the human population are asymptomatically and permanently colonized with nasal Staphylococcus aureus. To successfully colonize human nares, S. aureus needs to establish solid interactions with human nasal epithelial cells and overcome host defense mechanisms. However, some factors like bacterial interactions in the human nose can influence S. aureus colonization and sometimes prevent colonization. On the other hand, certain host characteristics and environmental factors can predispose to colonization. Nasal colonization can cause opportunistic and sometimes life-threatening infections such as surgical site infections or other infections in non-surgical patients that increase morbidity, mortality as well as healthcare costs.

Prevalence of methicillin-resistant Staphylococcus aureus colonisation among healthcare workers at a tertiary care hospital in southeastern China

OBJECTIVES

The aim of this study was to investigate the carriage rates of Staphylococcus aureus and methicillin-resistant S. aureus (MRSA) among healthcare workers (HCWs) at a tertiary-care hospital in southeastern China and to analyse the epidemiological relatedness of the S. aureus isolates.

METHODS

A total of 242 pharynx swabs were collected in March-April 2016 from 242 HCWs working in seven different wards and departments. Isolates were identified as S. aureus based on morphology, coagulase test and Vitek test. Antimicrobial susceptibility testing was performed by using the Kirby-Bauer disk diffusion method. The epidemiological relatedness of the S. aureus isolates was determined by pulsed-field gel electrophoresis (PFGE).

RESULTS

From the 242 HCWs, 70 (28.9%) S. aureus strains, including 10 (4.1%) MRSA strains, were identified during screening, with the highest MRSA rate detected in nurses (8/107; 7.5%). Carriage rates of S. aureus and MRSA among surgical HCWs were 30.0% (63/210) and 4.3% (9/210), respectively. Methicillin-susceptible S. aureus (MSSA) isolates were grouped by PFGE analysis into five similar groups (A-E), with most isolates belonging to groups D and E, accounting for 63.0% of isolates. Furthermore, two MRSA isolates from gastrointestinal surgery had identical PFGE patterns.

CONCLUSIONS

The prevalence of S. aureus colonisation among HCWs was high in this hospital, although the MRSA carriage rate in surgical wards was low. The identical PFGE pattern detected in two MRSA isolates from the same surgical department supports that effective control for possible cross-infection should be implemented.

Determinants of methicillin-resistant Staphylococcus aureus (MRSA) prevalence in the Asia-Pacific region: A systematic review and meta-analysis

OBJECTIVES

Published literature on methicillin-resistant Staphylococcus aureus (MRSA) in the Asia-Pacific region was reviewed to document the prevalence of MRSA in the region and to examine the impact of variability in study design on the reported MRSA prevalence data.

METHODS

This review included studies reporting MRSA prevalence between 2000 and 2016. Studies were excluded if they did not contain complete information on antimicrobial susceptibility testing (AST) methods. Primary outcomes were the proportion of MRSA among S. aureus isolates (resistance proportion) or among individual samples (prevalence).

RESULTS

A total of 229 studies in 19 countries/territories were included in the study. There was substantial heterogeneity in both outcomes (resistance proportion, I²=99.59%; prevalence, I²=99.83%), precluding pooled averages, and meta-regression analyses revealed that these variations were explained by country income status and participant characteristics but not by methodological differences in AST. Also, no significant secular changes in MRSA prevalence or resistance proportions in Asia-Pacific were found.

CONCLUSION

The resistance proportions and prevalence of MRSA infections in Asia-Pacific are comparable with those reported in other regions with no significant secular changes in the past decade. Country income status and characteristics of the sample population explained more variation in the reported resistance proportions and prevalence of MRSA than methodological differences in AST across locations in the region.

Methicillin-resistant Staphylococcus aureus nasal carriage in international medical conference attendees

BACKGROUND

Carriage of methicillin-resistant Staphylococcus aureus (MRSA) is associated with its transmission. International travels and massive gatherings may accelerate such transmission. MRSA carriage was surveyed among the attendees of two international medical conferences held in Taipei in 2010.

METHODS

A total of 209 attendees from 23 countries were recruited. Nasal specimens were collected from each volunteer and subjected to polymerase chain reaction (PCR) detection for MRSA. Molecular analysis, including pulsed-field gel electrophoresis, multilocus sequence typing (MLST), typing of staphylococcal cassette chromosome mec (SCCmec) and staphylococcal protein A (spa) genes, and detection of Panton-Valentine leukocidin (PVL) and sasX genes, was performed.

RESULTS

MRSA carriage was detected in 10 (4.8%) attendees from Vietnam (3/8, 37.5%), Korea (2/6, 33.3%), Japan (2/41, 4.9%), Philippines (2/52, 3.8%), and Bangladesh (1/4, 25.0%). The proportion of MRSA colonizers was significantly higher in the local hospital group compared to those from the other groups (3/17 vs. 7/192, p < 0.05). Six MRSA isolates were available for molecular analysis. They all carried a type IV SCCmec gene. Five pulsotypes were identified; four genotypes, respectively, were identified by MLST and spa typing. None of the isolates carried either PVL or sasX genes. None of common molecular characteristics was shared by isolates from different countries. Most of these isolates were local endemic community clone in each country.

CONCLUSIONS

As healthcare workers, a certain proportion of international medical conference attendees harbored MRSA in their nares, mostly local endemic community clones in each country, which has the potential of spread among attendees.

Nasal carriage, risk factors and antimicrobial susceptibility pattern of methicillin resistant Staphylococcus aureus among healthcare workers in Adigrat and Wukro hospitals, Tigray, Northern Ethiopia

Objective

The aim of this study was to determine nasal carriage, risk factors and antimicrobial susceptibility pattern of methicillin resistant Staphylococcus aureus among health care-workers of Adigrat and Wukro hospitals Northern Ethiopia.

Results

The overall prevalence of S. aureus and methicillin resistance S. aureus (MRSA) in the present study were 12% (29/242) and 5.8% (14/242) respectively. The rate of MRSA among S. aureus was 48.3%(14/29). In this study, MRSA carriage was particularly higher among nurse professionals (7.8%) and surgical ward (17.1%). None of the MRSA isolates were sensitive to penicillin and ampicillin. However, low resistance was found for chloramphenicol and clindamycin. Being diabetic and use of hands rub was statistically significant with MRSA colonization.

Electronic supplementary material

The online version of this article (10.1186/s13104-018-3353-2) contains supplementary material, which is available to authorized users.

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

Background

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

Methods

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

Results

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

Conclusions

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

Electronic supplementary material

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

Effectiveness of preoperative decolonization with nasal povidone iodine in Chinese patients undergoing elective orthopedic surgery: a prospective cross-sectional study

Staphylococcus aureus colonization in the nares of patients undergoing elective orthopedic surgery increases the potential risk of surgical site infections. Methicillin-resistant S. aureus (MRSA) has gained recognition as a pathogen that is no longer only just a hospital-acquired pathogen. Patients positive for MRSA are associated with higher rates of morbidity and mortality following infection. MRSA is commonly found in the nares, and methicillin-sensitive S. aureus (MSSA) is even more prevalent. Recently, studies have determined that screening for this pathogen prior to surgery and diminishing staphylococcal infections at the surgical site will dramatically reduce surgical site infections. A nasal mupirocin treatment is shown to significantly reduce the colonization of the pathogen. However, this treatment is expensive and is currently not available in China. Thus, in this study, we first sought to determine the prevalence of MSSA/MSRA in patients undergoing elective orthopedic surgery in northern China, and then, we treated the positive patients with a nasal povidone-iodine swab. Here, we demonstrate a successful reduction in the colonization of S. aureus. We propose that this treatment could serve as a cost-effective means of eradicating this pathogen in patients undergoing elective orthopedic surgery, which might reduce the rate of surgical site infections.

Prevalence and Genetic Characteristics of Staphylococcus aureus and Staphylococcus argenteus Isolates Harboring Panton-Valentine Leukocidin, Enterotoxins, and TSST-1 Genes from Food Handlers in Myanmar

Asymptomatic carriers of toxigenic Staphylococcus aureus are potential source of diseases, including food poisoning. Toxigenic potential and genetic traits of colonizing S. aureus were investigated for 563 healthy food handlers in Myanmar. Carriage of S. aureus was found in 110 individuals (19.5%), and a total of 144 S. aureus isolates were recovered from nasal cavities (110 isolates) and hands (34 isolates). Panton-Valentine leucocidin genes (pvl) were detected in 18 isolates (12.5%), among which 11 isolates were classified into coa-VIa, agr type III, and ST1930 (CC96) that had been also detected in pvl-positive clinical isolates in Myanmar. A pvl-positive, ST2250 nasal isolate was identified as S. argenteus, a novel coagulase-positive staphylococcus species. Toxic shock syndrome toxin-1 (TSST-1) gene was detected in five pvl-negative isolates. All of the 144 isolates harbored at least one of the 21 enterotoxin(-like) gene(s). The most prevalent enterotoxin(-like) gene was selw (98%), followed by selx (97%), sei (28%), sely (28%), sem (26%), sel (24%), and sea and sec (22% each). Considerable genetic diversity with five groups was detected for selw. The present study revealed the relatively high rate of pvl, as well as the wide distribution of enterotoxin(-like) genes among colonizing S. aureus in Myanmar.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Molecular epidemiology of Staphylococcus aureus nasal colonization among patients and their parents /guardian in an Iranian referral hospital

INTRODUCTION

Carriage of Staphylococcus aureus in the nose appears to play a key role in the epidemiology and pathogenesis of infection. It is important to investigate the genetic relatedness of S. aureus and MRSA clones in different geographic regions. The aim of this study was to assess the nasal carriage rate of S. aureus, including MRSA strains in both hospitalized children and general adult population (parents/guardian). In addition, antibiotic susceptibility pattern and molecular diversity of S. aureus in both population was evaluated in an Iranian referral pediatrics Hospital.

MATERIAL AND METHODS

All samples were obtained through nasal screening of patients and general adult population at admission and discharge day. The prevalence, resistance, and molecular diversity of all S. aureus isolates were examined.

RESULTS

In the current study, nasal carriage of S. aureus and Staphylococcus non aureus was identified in 384 (26%) and 1004 (68%) of the study population. The prevalence of MRSA nasal carriage in children and adults was 6.6% (29 out of 438) and 2.8% (29 out of 1046), respectively. Among S. aureus strains isolated obtained from patients and general adult population at admission day, high sensitivity to most of the antibiotics such as vancomycin (100%), rifampin (95%), linezolid (94%), quinupristin/dalfopristin (94%), minocycline (94%), chloramphenicol (89%), gentamycin (87%), amikacin (87%), clindamycin (86%) and moxifloxacin (83%) was seen. The most resistance antibiotics were penicillin (96-98%) and methicillin (44-47%). The susceptibility patterns of nasal S. aureus strains isolated at discharge day was not statistically different from S. aureus isolates obtained at admission day. Admission S. aureus isolated strains of 77 patients (64%) were similar to the isolated S. aureus strains of discharge, while S. aureus isolated strains of 43 patients (36%) was not similar to the strain of discharge (had similarity of less than 70%).

CONCLUSION

High prevalence of nasal carriage of S. aureus and MRSA indicates the urgent need to improve strategies for management of S. aureus infections. Our findings are useful for understanding of S. aureus nasal colonization dynamics within the patients and general population. Surveillance for S. aureus in community settings can provide data on circulating strains and might help developing control measures for reducing of infection spread in hospitals.

Antimicrobial Resistance and Molecular Characteristics of Methicillin-Resistant Staphylococcus aureus Isolates from Child Patients of High-Risk Wards in Shenzhen, China

Methicillin-resistant Staphylococcus aureus (MRSA) strains are responsible for high rates of mortality and thus pose a substantial burden to public health worldwide. Here, we investigated the antimicrobial susceptibility and molecular characteristics of MRSA isolated from child patients at Shenzhen Children's Hospital. We characterized 140 MRSA strains through antimicrobial susceptibility testing. We further performed spa typing, multilocus sequence typing (MLST), staphylococcal cassette chromosome mec (SCCmec) analysis, pvl gene analysis, and pulsed-field gel electrophoresis (PFGE). The analyzed MRSA strains were found to be sensitive to most non-β-lactam antimicrobial agents. Sequence type (ST) 59 was found to be the most common MLST lineage (54.3%). Most MRSA isolates belonged to the SCCmec IV (64.3%) and V (22.8%) types. The MRSA-ST59-SCCmec IV-t437 clone was the most predominant strain that infected 28.6% of all patients studied. Moreover, 50.7% of MRSA isolates were found to be pvl-positive. We report preliminary data on the prevalence and distribution of MRSA genotypes in Shenzhen Children's Hospital. We characterized MRSA colonization dynamics in child patients in China, and our findings can serve as the basis for the development of strategies to prevent MRSA infection and transmission.

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.

Changing epidemiology of community-associated methicillin-resistant Staphylococcus aureus in the Asia-Pacific region

INTRODUCTION

Community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA) has become an important threat to public health in the Asia-Pacific region, which is characterized by a large population and relatively insufficient resources. Better understanding on the current status of CA-MRSA in the region is of paramount importance. Areas covered: This article reviews the published literatures on the prevalence, molecular epidemiology, colonization, and hospital spread of CA-MRSA. Expert commentary: The burden of CA-MRSA has been increasing in the past two decades. The molecular epidemiology of CA-MRSA in the Asia-Pacific region shows a marked diversity in each country. Still, some strains - multilocus sequence type (MLST) ST59, ST30, ST72, ST8, and ST772 - are unique clones that have successfully established themselves as predominant, often spreading into nosocomial settings. More coordinated and comprehensive surveillance to understand the true epidemiology of CA-MRSA in the Asia-Pacific region is urgently needed.

Molecular epidemiology and characteristic of virulence gene of community-acquired and hospital-acquired methicillin-resistant Staphylococcus aureus isolates in Sun Yat-sen Memorial hospital, Guangzhou, Southern China

Background

Methicillin-resistant Staphylococcus aureus (MRSA) is a major cause of both hospital and community infections globally. It’s important to illuminate the differences between community-acquired MRSA (CA-MRSA) and hospital-acquired MRSA (HA-MRSA), but there have been confusions on the definition, especially for the MRSA isolates identified within 48 h of admission. This study aimed to determine the molecular characteristics and virulence genes profile of CA and HA-MRSA isolates identified less than 48 h after hospital admission in our region.

Methods

A total 62 MRSA isolates identified within 48 h after admission and the clinical data were collected. Antimicrobial susceptibility test (AST) of collected isolates were performed according to the guidelines of Clinical and Laboratory Standards Institute (CLSI) 2015, and staphylococcal cassette chromosome mec (SCCmec) typing, multilocus sequence typing (MLST), pulsed-field gel electrophoresis (PFGE) and virulence gene profiling were performed to explore the molecular diversity.

Results

SCCmec III and sequence type (ST) 239 were the most prevalent SCCmec type and ST in both CA and HA-MRSA groups. HA-MRSA group had higher prevalence of SCCmec III (87.2 %) and ST239 (79.5 %) compared with CA-MRSA (60.9 and 43.4 %, both P < 0.001), while the frequency of SCCmec IV (26.0 %) and ST59 (21.7 %) were higher in CA-MRSA than its counterpart (P < 0.001 and P = 0.003). MRSA-ST239-III was the predominant type in this study (61.3 %, 38/62), especially in HA-MRSA group (76.9 %, 30/39). However, CA-MRSA strains exhibited more diversity in genotypes in this study. Meanwhile, CA-MRSA tended to have lower resistant percentage to non-β-lactams antibiotics but more virulence genes carriage, especially the staphylococcal enterotoxins (SE) genes. Notably, seb gene was only detected in CA-MRSA isolates (52.2 %), likely a significant marker for CA-MRSA isolates. Panton-Valentine leukocidin gene (PVL) was highly detected in both groups, while appeared no significantly different between CA-MRSA (47.8 %) and HA-MRSA (43.6 %).

Conclusions

Our findings support a difference in the molecular epidemiology and virulence genes profile of CA-MRSA and HA-MRSA. Furthermore, this study indicates a possible transmission from HA-MRSA to CA-MRSA, which may cause the overlap of the definition.

Electronic supplementary material

The online version of this article (doi:10.1186/s12879-016-1684-y) contains supplementary material, which is available to authorized users.

Staphylococcus aureus Toxins and Diabetic Foot Ulcers: Role in Pathogenesis and Interest in Diagnosis

Infection of foot ulcers is a common, often severe and costly complication in diabetes. Diabetic foot infections (DFI) are mainly polymicrobial, and Staphylococcus aureus is the most frequent pathogen isolated. The numerous virulence factors and toxins produced by S. aureus during an infection are well characterized. However, some particular features could be observed in DFI. The aim of this review is to describe the role of S. aureus in DFI and the implication of its toxins in the establishment of the infection. Studies on this issue have helped to distinguish two S. aureus populations in DFI: toxinogenic S. aureus strains (harboring exfoliatin-, EDIN-, PVL- or TSST-encoding genes) and non-toxinogenic strains. Toxinogenic strains are often present in infections with a more severe grade and systemic impact, whereas non-toxinogenic strains seem to remain localized in deep structures and bone involving diabetic foot osteomyelitis. Testing the virulence profile of bacteria seems to be a promising way to predict the behavior of S. aureus in the chronic wounds.

Presence of the Panton-Valentine Leukocidin Genes in Methicillin-Resistant Staphylococcus aureus Is Associated with Severity and Clinical Outcome of Hospital-Acquired Pneumonia in a Single Center Study in China

The Panton-Valentine leukocidin (PVL) genes of methicillin-resistant Staphylococcus aureus (MRSA) have previously been associated with severe infections. Here, the impact of the PVL genes on severity of disease and clinical outcome of patients with hospital-acquired pneumonia (HAP) or ventilator-associated pneumonia (VAP) due to MRSA was investigated in a single center observational study in a hospital in China. HAP due to MRSA was diagnosed in 100 patients and 13 of the patients were PVL positive, while VAP was diagnosed in 5 patients and 2 were PVL positive. The PVL positive patient group showed a significantly higher Acute Physiology and Chronic Health Evaluation (APACHE) II score (14.3 ±7.8 vs. 10.1 ±4.7, P = 0.005) and significantly more patients with CRP levels >80 mg/L (8/15 vs. 12/90, P = 0.006) or WBC counts >15x109/L (7/15 vs. 12/90, P = 0.006), indicating that the severity of disease is affected by the presence of the PVL genes. The outcome of the study was defined by 30-day mortality. Four (27%) of the PVL positive patients and four (4%) of the PVL negative patients died within 30 days (P = 0.01, Fisher exact test). Kaplan-Meier survival curves were generated for the PVL positive and PVL negative patient groups, which differed significantly (P = 0.003). Among the patients that died, the mean interval between diagnosis and death was shorter for the PVL positive patients (9.3 ±5.6 vs. 40.8 ±6.6 days, P = 0.013). Further analysis within the HAP and VAP patient groups showed that the presence of PVL in MRSA impacted the severity of disease and clinical outcome of HAP, but for VAP the number of patients included in the study was too low. In conclusion, in this single center study in a Chinese hospital the presence of the PVL genes in MRSA impacted the severity of disease and clinical outcome in patients with HAP due to MRSA.