Clonal diversity and genomic characterization of Panton-valentine Leukocidin (PVL)-positive Staphylococcus aureus in Tehran, Iran

Genotypic and phenotypic characterization of virulence in methicillin resistant Staphylococcus aureus isolated from a local hospital of Ahmedabad, Gujarat, India

BACKGROUND

Staphylococcus aureus is a causative agent of diseases ranging from skin and soft tissue infections to several other invasive diseases such as bacteraemia, osteomyelitis, and pneumonia, as well as various non-invasive diseases due to secretion of diverse array of virulence factors. The aim of this study was to establish a correlation between antibiotic resistance, virulence traits, genotypes and infections caused by MRSA in a local hospital of Ahmedabad, Gujarat, India.

METHOD

For this study, 118 S. aureus isolates were obtained from the Microbiology Department of Sheth L.G General Hospital, Ahmedabad, Gujarat, India during the period of March 2022 to September 2022. The isolates were subjected to antibiotic susceptibility, phenotypic characterization of virulence traits, genotypic characterization of adhesion and virulence genes as well as genotyping of agr and SCCmec types.

RESULTS

This study reports 55.93% isolates from males and 44.07% isolates from females. 88.98% of isolates were associated with cases of skin and soft tissue infections (SSTIs), one of the most common infections associated with S. aureus. All the isolates were multidrug resistant (MDR). Phenotypically, 95.76% of isolates were reported to be either strong or moderate biofilm producers, 94.07% of isolates showed strong or moderate lipolytic activity and 91.53% of isolates were β- haemolytic. Genotypically, adhesion genes, ebpS, eno, sarA, fnbA and cna were reported in 94.07%, 93.22%, 82.20%, 78.81% and 67.80% of isolates, respectively and virulence genes, spA, SE family, coa, pvl and tsst, were reported in 99.15%, 97.46%, 84.75%, 77.12% and 50% of isolates, respectively. agr typing and SCCmec classification revealed agr type I (61.02%) and SCCmec type III (35.59%) to be the most prevalent type. The antibiotic resistance, biofilm formation and presence of adhesion and virulence genes were found to be associated with agr type I and III and SCCmec type I, III and IV. A strong correlation was observed between isolates obtained from pus samples and agr type I, II and III, SCCmec type I, IA, II, III, IIIA, IIIB and IV, biofilm formation, haemolysis, lipolysis and prevalence of adhesion and virulence genes.

CONCLUSION

SSTIs was the most common infection associated with S. aureus. Maximum antibiotic resistance was reported against β lactam, fluoroquinolones and macrolides class of antibiotics. Majority of isolates were strong biofilm producers, β- hemolytic, lipolytic and belonged to agr type I and SCCmec type III. Isolates belonging to agr type I and III and SCCmec type I, III and IV were found to be more virulent.

Current innovations in mRNA vaccines for targeting multidrug-resistant ESKAPE pathogens

The prevalence of multidrug-resistant (MDR) ESKAPE pathogens, including Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, and Pseudomonas aeruginosa, represents a critical global public health challenge. In response, mRNA vaccines offer an adaptable and scalable platform for immunotherapy against ESKAPE pathogens by encoding specific antigens that stimulate B-cell-driven antibody production and CD8+ T-cell-mediated cytotoxicity, effectively neutralizing these pathogens and combating resistance. This review examines recent advancements and ongoing challenges in the development of mRNA vaccines targeting MDR ESKAPE pathogens. We explore antigen selection, the nuances of mRNA vaccine technology, and the complex interactions between bacterial infections and antibiotic resistance. By assessing the potential efficacy of mRNA vaccines and addressing key barriers to their paraclinical implementation, this review highlights the promising function of mRNA-based immunization in combating MDR ESKAPE pathogens.

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.

Molecular characterisation of Staphylococcus aureus in school-age children in Guangzhou: associations among agr types, virulence genes, sequence types, and antibiotic resistant phenotypes

BACKGROUND

Staphylococcus aureus, one of the most prevalent opportunistic pathogens, mainly colonizes the nasal cavity and is a risk factor for severe infections. Virulence factors and accessory gene regulator (agr) are key to the severity and diversity of staphylococcal infection. In this study, we aimed to characterise S. aureus agr-types and virulence genes and correlated them with genetic background and antibiotic-resistant phenotypes.

RESULTS

Agr types were identified in 704 isolates (98.5%), with only 11 isolates were negative for agr type. Most of our isolates were classified as agr type I, followed by types III, II and IV. The enterotoxin c gene (sec) was detected in 48.6% of isolates, showing the highest prevalence among the five enterotoxin genes detected. The positivity rates for the lukS/F-PV and tsst genes were 4% and 2.2%, respectively, while neither sed nor SasX were detected. ST45, ST59, ST338, ST188, ST6, ST7, ST22, ST25, ST398, and ST944 belonged to agr I group, while ST5 and ST15 belonged to agr II group. ST30 and ST1 were classified into agr III group, and ST121 was assigned into agr IV group. The tsst gene was found exclusively within agr I and III types belonging to ST7 and ST30 isolates, while the lukS/F-PV was predominantly carried by agr I type isolates primarily within CC59 and CC22 clones. Among the methicillin-resistant S. aureus (MRSA) isolates, 89.7% belonged to agr I group, and 97.8% of rifampicin-resistant or intermediate isolates were assigned to agr I group. MRSA isolates harboured more tested virulence genes compared to methicillin-susceptible S. aureus isolates.

CONCLUSIONS

We characterized the distributions of agr types and eight major virulence genes of 715 S. aureus isolates, and our findings revealed clear associations between agr types and STs, as well as virulence genes, and drug resistant phenotypes.

Prevalence of Panton-Valentine leukocidin and toxic shock syndrome toxin-1 genes in methicillin-resistant Staphylococcus aureus isolated from nose of restaurant workers in Kirkuk city

Staphylococcus aureus resides naturally in the nasal cavity of healthy individuals, including those working in restaurants, so they may be a source for spreading this bacterium to restaurant customers directly or indirectly through cooked meals. This bacterium has several virulence factors enabling it to cause many diseases in different parts of the body. It has also the capability to resist conventional antibiotics including methicillin. To investigate methicillin-resistant S. aureus (MRSA), 170 nasal swabs were collected from food preparation workers in 30 restaurants (5-6 workers in each restaurant) in Kirkuk city. After collection, the samples were directly transferred to the laboratory and cultured on selective media like mannitol salt agar (MSA). Microbiological examination including morphological, biochemical, and confirmatory tests showed that 24/170 of collected samples were positive for S. aureus with a rate of 14.12%. Among 24 isolates, 20 (83.3%) belonged to MRSA. All isolates were resistant to oxacillin and penicillin (100%), whereas sensitive to other antibiotics (gentamicin, chloramphenicol, and rifampicin). Polymerase chain reaction exhibited that 13 (65%) of MRSA isolates have toxic shock syndrome toxin-1 gene and only 4 (20%) have Panton-Valentine leukocidin gene.

Methicillin-resistant Staphylococcus aureus in China: a multicentre longitudinal study and whole-genome sequencing

The aim of this study was to investigate the genomic epidemiology of MRSA in China to identify predominant lineages and their associated genomic and phenotypic characteristics. In this study, we conducted whole-genome sequencing on 565 MRSA isolates from 7 provinces and municipalities of China between 2014 and 2020. MRSA isolates were subjected to MLST, spa typing, SCCmec typing, analysis of virulence determinants and antimicrobial susceptibility testing. Among 565 MRSA isolates tested, clonal complex (CC) 59 (31.2%), CC5 (23.4%) and CC8 (13.63%) were the major lineages, and the clonal structure was dominated by ST59-t437-IV (14.9%), ST239-t030-III (6.4%) and ST5-t2460-II (6.0%), respectively. Of note, CC8, the predominant lineage in 2014–2015, was replaced by CC59 after 2016. Interestingly, the extension and unstable structure of the CC5 population was observed, with ST5-t311-II, ST764-t1084-II, ST5-t2460-II and ST764-t002-II existing complex competition. Further analysis revealed that virulence determinant profiles and antibiograms were closely associated with the clonal lineage. The CC59 MRSA was less resistant to most tested antimicrobials and carried fewer resistance determinants. But rifampicin resistance and mupirocin resistance were closely linked with CC8 and CC5, respectively. MRSA isolates conservatively carried multiple virulence genes involved in various functions. PVL encoding genes were more common in ST338, CC30, CC398, ST8 and CC22, while tsst-1 was associated with ST5. In conclusion, the community-associated CC59-ST59-t437-IV lineage was predominant in China, with diverse clonal isolates alternately circulating in various geographical locations. Our study highlights the need for MRSA surveillance in China to monitor changes in MRSA epidemiology.