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

Nasal carriage rate, associated factors, and antimicrobial susceptibility patterns of methicillin resistance Staphylococcus aureus among pre-clinical undergraduate students at the College of Health and Medical Sciences, Haramaya University, Ethiopia

Background

Staphylococcus aureus nasal carriage has been linked to higher rates of infection and morbidity. People with Methicillin-resistant Staphylococcus aureus can be a potential source of infection for others. University students living together in crowded conditions increase their risk of acquiring infections. The prevalence of S. aureus, particularly Methicillin-resistant Staphylococcus aureus nasal carriage, in Ethiopian university students is sparse.

Objective

This study aimed to determine the nasal carriage rate, associated factors, and antimicrobial susceptibility patterns of methicillin-resistant Staphylococcus aureus among pre-clinical students at the College of Health and Medical Sciences, Haramaya University, Ethiopia, from 1 July to 30 August 2022.

Methods

An institutional-based cross-sectional study was conducted among 270 randomly selected pre-clinical Health and Medical Sciences students. Data on associated factors were collected using pre-tested, structured questionnaires. A nasal swab was taken from each participant and sent to the microbiology laboratory via Amies transport media in a cold chain. There, it was cultivated using conventional techniques. The isolated colonies were found to be S. aureus, and its antimicrobial susceptibility was performed using the Kirby-Bauer disk diffusion method on Muller-Hinton agar. Methicillin-resistant Staphylococcus aureus expressing using cefoxitin based on CLSI breakpoint. Data were entered into Epi-Data version 4.4.2.1 and exported to the Statistical Package for Social Sciences (SPSS) software version 25 for analysis. Pearson's chi-square test was performed to predict the associations between variables. A p-value less than 0.05 was regarded as statistically significant.

Result

Methicillin-resistant Staphylococcus aureus nasal carriage was 5.9% (95% CI: 3.09-8.7) of cases of S. aureus nasal colonization, which was found to be 12.96% (95% CI: 8.85-16.96). Methicillin-resistant Staphylococcus aureus nasal colonization was significantly associated with the history of cigarette smoking (p = 0.000), intake of khat (p = 0.042), nose-picking habit (p = 0.003), history of sharing personal goods (p = 0.021), and history of hospitalizations (p = 0.00). All of the Methicillin-resistant Staphylococcus aureus isolates were resistant to ampicillin and cefoxitin.

Conclusion

Based on the findings, a considerable proportion of healthy students harbored Methicillin-resistant Staphylococcus aureus strains associated with behavioral factors. Furthermore, these isolates showed high resistance to cefoxitin and ampicillin. Hence, it is crucial to regularly test pre-clinical students to prevent endogenous infections and the spread of Methicillin-resistant Staphylococcus aureus.

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

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

Investigating the relationship between muscle mass and nasal Methicillin-Resistant Staphylococcus aureus (MRSA) colonization: Analysis of the National Health and Nutrition Examination Survey (NHANES)

BACKGROUND

Methicillin-resistant Staphylococcus aureus (MRSA) nasal colonization is associated with an increased risk of infection disease. Low muscle mass has been linked to higher levels of inflammatory markers and weakened immune response, which may impact the susceptibility to nasal MRSA colonization. The relationship between muscle function and immune response to pathogens may be bidirectional. This study investigates the association between muscle mass and nasal MRSA colonization in adults.

METHODS

The present cross-sectional study utilized data from the National Health and Nutrition Examination Survey (NHANES) conducted between 2001 and 2004. Appendicular skeletal muscle mass (ASM) adjusted by body mass index (BMI) (ASM/BMI) was used to evaluate muscle mass. Multivariate logistic regression, adjusted for demographic and infection factors, was used to analyze the association between muscle mass and nasal colonization by MRSA. A subgroup analysis based on age and gender was performed to assess the impact of muscle mass on nasal MRSA colonization.

RESULTS

Nasal MRSA colonization was more prevalent in females, those with smaller household sizes, lower income, lower ASM/BMI, those who had stayed in healthcare facilities in the past 12 months, and individuals with diabetes and smoking habits. After adjusting for confounding factors, a dose-dependent association was found between decreasing quartiles of ASM/BMI and the risk of nasal MRSA colonization (p < 0.05). Additionally, per 1 unit increase in ASM/BMI was related to a 64% lower risk of nasal MRSA colonization.

CONCLUSIONS

This study suggests a significant negative correlation between ASM/BMI and the risk of nasal MRSA colonization. However, more prospective studies are required to investigate the causal relationship between muscle mass and colonization.

Molecular analysis of Panton-Valentine Leucocidin (pvl) gene among MRSA and MSSA isolates

The present study was conducted in order to determine the frequency of pvl gene among the pathogenic and healthy population isolates of Methicillin Resistant Staphylococcus aureus (MRSA) and Methicillin Sensitive Staphylococcus aureus (MSSA). For this purpose, nasal swab samples were collected from the healthy individuals (to be used as controls, all the samples were collected irrespective of the sex and age factors), the pathogenic samples were collected from different patients suffering from skin &soft tissue infections caused by S. aureus (to be used as test samples).Both of these population samples were analyzed for the presence of pvl gene. S.aureus were identified through conventional microbiological identification procedures. In the case of normal samples, 70 nasal swabs were collected and only 33 (47%) proved to be S. aureus while 20 pathogenic samples were collected and all (100%) were cleared as S. aureus. For further distribution of samples into MRSA and MSSA, antibiotic susceptibility pattern was checked by using the standard protocols of Kirby-Bauer disc diffusion method. Two antibiotic discs Oxacillin (OX: 1ug) and cefoxitin (FOX: 30ug) were used. Among healthy population, MRSA was found to be 79% (n=26) and MSSA were present as 21% (n= 7). Among pathogenic strains 100% MRSA was detected where n= 20. Detection of pvl gene among the MRSA and MSSA isolates was done by using the uniplex PCR followed by gel electrophoresis. MRSA and MSSA of normal healthy population carried 49% and 7% pvl gene respectively. While, pathogenic MRSA samples carried 46% pvl gene among them. Potentially alarming percentage of pvl gene is present among the normal healthy individuals which indicates a future threat and a major health concern.

Alhoot M, Abdul Karim S. Multidrug-Resistant Staphylococcus aureus as Coloniser in Healthy Individuals

Staphylococcus aureus is a common human pathogen that can cause mild superficial infections to deep-seated abscesses and sepsis. One of the characteristics of S. aureus is the ability to colonise healthy individuals while leaving them asymptomatic. These carriers’ risk harbouring an antibiotic-resistant strain that may be harmful to the individual and the community. S. aureus carriage in healthcare personnel is being studied extensively in many parts of the world. However, the relationship between colonisation and disease among those with no previous exposure to healthcare remains untouched. Colonisation of the nasal cavity and its surrounding by pathogenic organisms such as S. aureus leads to the increased risk of infection. Hospital-acquired infections associated with S. aureus infections are common and studies related to these types of infections among various study groups are largely documented. However, over the last decade, an increase in community-associated methicillin-resistant S. aureus has been noted, increasing the need to identify the prevalence of the organism among healthy individuals and assessing the antibiotic resistance patterns. Systemic surveillance of the community for colonisation of S. aureus and identifying the antibiotic-resistant pattern is critical to determine the appropriate empiric antibiotic treatment.

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.

Increased dietary manganese impairs NET formation rendering neutrophils ineffective at combating Staphylococcus aureus

Dietary metals can modify the risk to infection. Previously, we demonstrated that heightened dietary manganese (Mn) during systemic Staphylococcus aureus infection increases S. aureus virulence. However, immune cells also operate in these same environments and the effect of dietary Mn on neutrophil function in vivo has not been assessed. This study reveals that increased concentrations of Mn impairs mitochondrial respiration and superoxide production in neutrophils responding to S. aureus. As a result, high Mn accelerates primary degranulation, while impairing suicidal neutrophil extracellular trap (NET) formation, which decreases bactericidal activity. In vivo, elevated dietary Mn accumulated extracellularly in the heart, indicating that excess Mn may be more bioavailable in the heart. Coinciding with this phenotype, neutrophil function in the heart was most impacted by a high Mn diet, as neutrophils produced lower levels of mitochondrial superoxide and underwent less suicidal NET formation. Consistent with an ineffective neutrophil response when mice are on a high Mn diet, S. aureus burdens were increased in the heart and mice were more susceptible to systemic infection. Therefore, elevated dietary Mn not only affects S. aureus but also renders neutrophils less capable of restricting staphylococcal infection.

Identification of methicillin-resistant Staphylococcus aureus ST8 isolates in China with potential high virulence

Methicillin-resistant Staphylococcus aureus (MRSA) ST8 strains have spread worldwide, causing outbreaks in various regions. However, this clone has only been sporadically reported in China. Consequently, detailed information regarding the phylogeny and potential virulence of S. aureus ST8 strains in China remains unknown. In this study, we characterized six ST8 strains collected from three tertiary hospitals in China, including three MRSA (MR50, MR526, and MR254) and three MSSA (H78, H849 and H863). Whole genome sequencing and phylogenetic analysis showed that the six strains formed two separate clusters, including two (MR50 and MR526) and four (MR254, H78, H849 and H863) isolates, respectively. Among them, MR50 and MR526 harboured spa t008, SCCmec IVa, arginine catabolic mobile element, and were phylogenetically close to the epidemic USA300 strains, while other four strains belonged to spa t9101 and formed a unique branch. MR254 carried a novel hybrid SCCmec element (namely SCCmec254). Same as the USA300 prototype strain LAC, the China S. aureus ST8 strains produced weak biofilms except MR254. Among them, MR254 had significantly stronger haemolysis ability and higher α-toxin levels than others, while MR526 showed comparable haemolysis and α-toxin production levels as USA300-LAC. In mouse skin abscess model, MR254 showed particularly strong invasions, accompanied by necrosis, while MR526 exhibited similar infection levels as USA300-LAC. These data suggested that the China MRSA ST8 isolates (e.g. MR254 and MR526) were highly virulent, displaying higher or similar virulence potential as the epidemic USA300 strain. Active surveillance should be enacted to closely monitor the further spread of these hyper-virulent MRSA strains in China.

Active Surveillance, Drug Resistance, and Genotypic Profiling of Staphylococcus aureus Among School-Age Children in China

Methicillin-susceptible (MSSA) and methicillin-resistant Staphylococcus aureus (MRSA) nasal colonization predisposes individuals for endogenous infections and is a major threat to children. Recently, oxacillin/cefoxitin-susceptible mecA-positive S. aureus (OS-MRSA) has been reported worldwide. Herein, a prospective, cross-sectional study was conducted across five schools, representing three educational stages, in Guangzhou, China. Nasal swabs from 2,375 students were cultured for S. aureus and all isolates were subjected to antibiotic susceptibility testing phenotypically and confirmed by femB and mecA genetic detection; all the isolates were classified as MSSA, MRSA, or OS-MRSA. All strains were also analyzed by multi-locus sequence typing. Among the 2,375 swabs, S. aureus was detected in 744 children (31.3%, 95% CI: 25.9–36.7%), of whom 72 had MRSA (3.0%, 95% CI: 0.6–5.4%) and 4 had OS-MRSA (0.2%, 95% CI: 0.1–0.3%), of which an oxacillin- and cefoxitin-susceptible MRSA strain was identified. The prevalence of S. aureus and MRSA was higher in younger children. The highest percentage of drug resistance of the S. aureus isolates (n = 744) was to penicillin (85.5%), followed by erythromycin (43.3%) and clidamycin (41.0%). The most prevalent sequence types (STs) were ST30, ST45, and ST188 in MSSA, accounting for 38.7% of the total isolates, whereas ST45, ST59, and ST338 accounted for 74.6% of the MRSA isolates and ST338 accounted for 50.0% of the OS-MRSA isolates. The MRSA and OS-MRSA isolates (n = 76) were grouped into three clades and one singleton, with clonal complex (CC) 45 as the most predominant linkage. The top nine multi-locus sequence typing-based CCs (CC30, CC45, CC5, CC1, CC15, CC944, CC398, CC59, CC7) represented 86.7% of all S. aureus isolates. All CC30 isolates were resistant to erythromycin and clidamycin, and almost all these isolates were also resistant to penicillin (99.2%). The CC45 and CC59 isolates exhibited high resistance rates to oxacillin at 31.5 and 59.0%, respectively. This study provides updated data valuable for designing effective control strategies to mitigate the burden of disease and to improve the adequacy of empirical antimicrobial treatments for potentially harmful infections.

Ecology and Genetic Lineages of Nasal Staphylococcus aureus and MRSA Carriage in Healthy Persons with or without Animal-Related Occupational Risks of Colonization: A Review of Global Reports

In this conceptual review, we thoroughly searched for appropriate English articles on nasal staphylococci carriage among healthy people with no reported risk of colonization (Group A), food handlers (Group B), veterinarians (Group C), and livestock farmers (Group D) published between 2000 and 2021. Random-effects analyses of proportions were performed to determine the pooled prevalence of S. aureus, MRSA, MRSA-CC398, and MSSA-CC398, as well as the prevalence of PVL-positive S. aureus from all eligible studies. A total of 166 eligible papers were evaluated for Groups A/B/C/D (n = 58/31/26/51). The pooled prevalence of S. aureus and MRSA in healthy humans of Groups A to D were 15.9, 7.8, 34.9, and 27.1%, and 0.8, 0.9, 8.6, and 13.5%, respectively. The pooled prevalence of MRSA-CC398 nasal carriage among healthy humans was as follows: Group A/B (<0.05%), Group C (1.4%), Group D (5.4%); and the following among Group D: pig farmers (8.4%) and dairy farmers (4.7%). The pooled prevalence of CC398 lineage among the MSSA and MRSA isolates from studies of the four groups were Group A (2.9 and 6.9%), B (1.5 and 0.0%), C (47.6% in MRSA), and D (11.5 and 58.8%). Moreover, MSSA-CC398 isolates of Groups A and B were mostly of spa-t571 (animal-independent clade), while those of Groups C and D were spa-t011 and t034. The MRSA-CC398 was predominately of t011 and t034 in all the groups (with few other spa-types, livestock-associated clades). The pooled prevalence of MSSA and MRSA isolates carrying the PVL encoding genes were 11.5 and 9.6% (ranges: 0.0-76.9 and 0.0-28.6%), respectively. Moreover, one PVL-positive MSSA-t011-CC398 isolate was detected in Group A. Contact with livestock and veterinary practice seems to increase the risk of carrying MRSA-CC398, but not in food handlers. Thus, this emphasizes the need for integrated molecular epidemiology of zoonotic staphylococci.

Molecular Characteristics of Staphylococcus aureus From Food Samples and Food Poisoning Outbreaks in Shijiazhuang, China

As an opportunistic pathogen worldwide, Staphylococcus aureus can cause food poisoning and human infections. This study investigated the sequence typing, the penicillin (blaZ) and methicillin (mec) resistance profiles of S. aureus from food samples and food poisoning outbreaks in Shijiazhuang City, and the staphylococcal enterotoxin (SE) types of the S. aureus isolates from food poisoning. A total of 138 foodborne S. aureus isolates were distributed into 8 clonal complexes (CCs) and 12 singletons. CC1, CC5, CC8, CC15, CC97, CC59, CC398, CC88, and CC7 were the predominant CCs of foodborne S. aureus isolates. Moreover, CC59, CC15, and CC5 were the most prevalent CCs in food poisoning outbreaks. SEE was the most commonly detected SE in food poisoning isolates. One hundred thirty-three S. aureus isolates harbored the penicillin-resistant gene blaZ, and nine isolates carried the mec gene. The present study further explained the relationship between S. aureus and foods and food poisoning and indicated the potential risk of S. aureus infection.

Prevalence of Staphylococcus aureus nasal carriage and surgical site infection rate among patients undergoing elective cardiac surgery

BACKGROUND

Nasal carriers of Staphylococcus aureus are at increased risk of postoperative surgical site infection. Nasal decolonization with mupirocin is recommended in patients undergoing cardiac surgery to reduce surgical site infection. These data are still lacking in Thailand. Therefore, the aim of this study was to determine the prevalence of S. aureus nasal carriage in Thai patients undergoing elective cardiac surgery. The association of surgical site infection and S. aureus nasal carriage was also examined.

METHODS

This was a prospective cohort study of 352 patients who planned to undergo elective cardiac surgery. Nasal swab culture was performed in all patients preoperatively.

RESULTS

Of 352 patients, 46 (13.1%) had a positive nasal swab culture for methicillin-sensitive S. aureus (MSSA) and one patient (0.3%) harbored a methicillin-resistant S. aureus (MRSA) strain. The incidence of superficial and deep surgical site infection was 1.3% and 0.3%, respectively. After multivariate analysis, S. aureus nasal carriage was independently associated with superficial surgical site infection (odds ratio 13.04, 95% confidence interval 1.28-133.27; P=0.03).

CONCLUSIONS

The prevalence of MSSA and MRSA nasal carriage in Thai patients undergoing elective cardiac surgery was low. The incidence of surgical site infection was also very low in the population studied. Nevertheless, it was found that S. aureus nasal carriage increased the risk of superficial surgical site infection.

Phenotypic and Molecular Screening of Nasal S. aureus from Adult Hospitalized Patients for Methicillin- and Vancomycin-resistance

INTRODUCTION

Nasal carriers of Staphylococcus aureus are common and play an important role in the transmission of infections. The aim of this study is a phenotypic and molecular investigation of nasal methicillin- and vancomycin-resistant S. aureus in hospitalized patients.

METHODS

202 nasal swabs were collected from patients at Prince Hamzah Hospital, Jordan, through 2016-2017. Swabs were processed according to standard microbiological procedures to isolate Staphylococci. Antibiotic susceptibility testing was performed using disk diffusion, E-test, microdilution and Vitek 2. Methicillin resistance was confirmed by testing for the mecA gene, while vancomycin resistance was screened by testing for the vanA and vanB genes.

RESULTS

The mean age of participants was 50.17±18.18 years and 59.4% were females. Nasal Staphylococci was isolated in 64/202 (31.7%), S. aureus was isolated from 33 samples (16.3%), MRSA was isolated from 13 samples (6.4%) and constitutive Macrolide-lincosamidestreptogramin B (MLSB) was isolated from 12 samples (5.9%). All MRSA isolates harbored the mecA gene. All isolates were sensitive to vancomycin using E-test and the microdilution test and were negative for the vanA and vanB genes. The highest resistance rate was observed for benzylpenicillin (>90%), while the lowest resistance rate was for tobramycin (<5%) among all isolates. Nasal Staphylococci, S. aureus and MRSA colonization significantly correlate with increased number of family members and previous hospitalization (P<0.05), while nasal S. aureus significantly correlates with a history of skin infection (P=0.003).

CONCLUSION

Nasal colonization by mecA-mediated MRSA is common among hospitalized patients, while vanA- and vanB-mediated vancomycin resistance was not detected in any nasal isolates.

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.

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.

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.

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.

Phylogenetic analysis and virulence determinant of the host-adapted Staphylococcus aureus lineage ST188 in China

Staphylococcus aureus (S. aureus) is an important pathogen of humans and livestock species, but an understanding of the clonal distribution of S. aureus causing different host-species infections in the same geographical environment and within the same period is lacking. By characterizing infections caused by S. aureus in bovine, pediatric, and adult patients in Shanghai, China, between 2012 and 2014, we identified methicillin-sensitive S. aureus (MSSA) ST188 as the major lineage causing infections in multiple host species. Whole-genome sequencing and phenotypic analyses demonstrated that ST188 might evolve from livestock, and there was no significant genomic or virulence difference between ST188 isolated from livestock and humans. The virulence of ST188 is related to its adhesion and nasal colonization ability. This result is in accord with the strong epithelial cell adhesion and biofilm formation properties of ST188. Furthermore, the adhesion- and biofilm-formation-related genes are present in multiple copies and exhibit significantly increased expression in ST188. In conclusion, S. aureus ST188 is the major lineage causing human and livestock infections in Shanghai, China. Due to its high expression of the factors associated with bacterial adhesion and biofilm formation, ST188 has the ability to colonize and infect different host species.

Effect of 2% Nasal Mupirocin Ointment on Decreasing Complications of Nasotracheal Intubation: A Randomized Controlled Trial

INTRODUCTION

In oral and maxillofacial surgeries, nasotracheal intubation is carried out to increase the surgeon's access to the oral cavity. During nasotracheal intubation the risk of trauma is higher than that in orotracheal intubation as there is passage of the tube through the mucosa of the nasal tract due to which bacteria might get transported into the trachea.

AIM

To evaluate the effect of 2% nasal mupirocin ointment before and after nasotracheal intubation on decreasing the complications of intubation for oral and maxillofacial surgeries.

MATERIALS AND METHODS

In the present single blinded randomised controlled clinical trial, 44 patients were randomly assigned to two equal groups. A sterile swab was used, eight to 10 hours before nasotracheal intubation, to take a sample for culturing from the vestibule of nostrils and the anterior septum of the patients. In Group 1, 2% nasal mupirocin ointment was applied to the vestibules of both nostrils and the anterior septum. In Group 2, no intervention was carried out. After general anaesthesia and extubation, microbial cultures were prepared from the 4 cm distal end of the tube and antibiogram test was carried out. Also, the patients were compared in terms of the severity of nasal bleeding, the ease of breathing through the nose after nasotracheal intubation. Data were analysed with suitable statistical tests.

RESULTS

In the mupirocin group, 27.2% of the subjects were carriers of Staphylococcus aureus in the nasal cavity but no S. aureus was detected at the distal end of nasotracheal tube after extubation. In the control group, 18.2% of the subjects were carriers of Staphylococcus aureus in the nasal cavity but there was no change in the number of S. aureus counts at the distal end of nasotracheal tube (p-value<0.001). After extubation, in the mupirocin and control groups, 18.2% and 22.7% of the subjects, respectively, exhibited severe bleeding (p-value=0.001). In the mupirocin and control groups, 86.4% and 59.1% of the subjects had easy extubation, respectively (p-value=0.044). In the mupirocin and control groups, 9.1% and 63.7% of the subjects immediately after regaining consciousness and 9.1% and 54.6% three hours after extubation had difficulty in breathing, respectively (p-value=0.001).

CONCLUSION

Use of mupirocin before nasotracheal intubation decreased the complications of nasal intubation in addition to decreasing the risk of colonization of S. aureus and other gram-negative bacteria.