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PubMed2026

A comparative analysis of the clinical and genomic characteristics of Panton-Valentine leukocidin-positive methicillin-resistant Staphylococcus aureus in Korea and Japan.

Panton-Valentine leukocidin (PVL) is a leukocyte-lytic toxin produced by Staphylococcus aureus, which is primarily associated with skin and soft tissue infections. Notably, there has been an increase in the number of cases caused by the USA300 lineage in Japan. However, the reported prevalence of USA300 is limited in other Asian countries, including Korea. This study investigated the prevalence of PVL-positive methicillin-resistant S. aureus (MRSA) in Korea and Japan and compared their molecular epidemiological characteristics. A total of 463 MRSA strains were analyzed, comprising 283 strains from patients visiting two hospitals in Seongnam and Seoul, Korea, and 180 strains from six hospitals in Tokyo, Japan, between 2018 and 2019. The PVL-encoding genes lukS/F-PV were detected using PCR. Molecular epidemiological and phylogenetic analyses were performed using next-generation sequencing. Overall, 27 (9.5%) PVL-positive MRSA strains were detected among strains isolated from Korea, and 16 (8.9%) were detected among those isolated from Japan. Genotyping of PVL-positive strains revealed that 85.2% of Korean and 81.3% of Japanese strains belonged to USA300. Most USA300 strains from Japan and Korea formed distinct clusters in phylogenetic analyses. Meanwhile, ΨUSA300 and ST22-PT, clones that are prevalent in Japan, were isolated in Korea. This study showed that USA300 strains, which are becoming more prevalent in Japan, are also present in Korea. Furthermore, this study suggests that ΨUSA300 and ST22-PT may be spreading between these two countries. Therefore, it is necessary to continue monitoring the epidemiological trends of PVL-positive MRSA clones both domestically and internationally.IMPORTANCEPanton-Valentine leukocidin (PVL) is a major toxin produced by Staphylococcus aureus. Although a rapid increase in PVL-positive strains has been reported in Japan, data on PVL-positive strains in Korea remain limited. In this study, we performed a comparative analysis of PVL-positive S. aureus isolates from Korea and Japan. The results showed that the clinical backgrounds and genetic profiles of PVL-positive strains isolated in Korea and Japan were highly similar. Furthermore, we confirmed for the first time that clones circulating in Japan, including ΨUSA300 and ST22-PT, were also isolated in Korea. These findings provide valuable insights into the epidemiological status of PVL-positive S. aureus in East Asia.

Leukocidins↗
PubMed2025

Molecular epidemiology of panton valentine leukocidin-producing Staphylococcus aureus infections, Djibouti, 2018-2023.

Between 2018 and 2023, a genomic study was conducted in a military camp in Djibouti to investigate the molecular epidemiology of Panton-Valentine Leukocidin-producing Staphylococcus aureus. Among 43 isolates, Sequence Type 152 was predominant (72%), mainly associated with spa types t355 and t4235. Core-genome Multi-Locus Sequence Typing revealed two concurrent transmission dynamics: localized inter-human outbreaks and repeated introductions from external sources. Comparative genomics with other African Sequence Type 152 isolates showed similar levels of diversity, suggesting a widespread continental dissemination. These findings highlight the importance of genomic surveillance to better understand and control the spread of this virulent lineage in Africa.

Leukocidins↗
PubMed2025

Isolation and Molecular Characterization of Three Staphylococcus pseudintermedius Strains from Dogs and Humans in Egypt.

Staphylococcus pseudintermedius is an opportunistic pathogen that is largely associated with canine hosts but is becoming more widely recognized as a zoonotic pathogen. Understanding its genetic and phenotypic properties, such as virulence factors and antimicrobial resistance (AMR) profiles, is critical for infection control and vaccine development. In this study, we isolated and molecularly characterized three S. pseudintermedius isolates from dogs (hereafter referred to as S. pseudintermedius D8) and humans (hereafter referred to as S. pseudintermedius H10 and S. pseudintermedius H11) in Egypt. All three isolates showed 100% sequence identity with the nuc gene of the S. pseudintermedius SP_11304-3A reference genome. Multilocus sequence typing (MLST) revealed novel sequence types (STs) in the three isolates. The AMR determinants varied substantially among the isolates. While the mecA gene was absent, blaZ was detected in the canine isolate, indicating beta-lactamase-mediated penicillin resistance. Additionally, tetK and tetM genes were found conferring tetracycline resistance in different isolates. Resistance genes for aminoglycosides, chloramphenicol, fusidic acid, macrolides, streptothricin, and trimethoprim were also identified. All isolates were positive for key virulence genes, including immune evasion (AdsA), coagulase (coa), immunoglobulin-binding protein (sbi/spsK), exfoliative toxin (speta), enterotoxins (se-int and siet), fibrinogen binding protein gene (fnbB), and two-component pore-forming leukocidin genes (lukF and lukS). The S. pseudintermedius H11 isolate uniquely harbored the neuraminidase gene (nanB), while none of the isolates contained the gene coding for immunoglobulin G binding protein (spsQ). These findings highlight the differences in virulence and antimicrobial resistance genes among these S. pseudintermedius isolates, underlining the need for global surveillance and molecular characterization of this pathogen.

Dogs↗
PubMed2025

Molecular landscape of methicillin-resistant Staphylococcus aureus strains in clinical infections from hospitals in Lagos, Nigeria.

BACKGROUND AND OBJECTIVES: Multidrug-resistant Staphylococcus aureus (MRSA) accounts for a significant proportion of antimicrobial resistance (AMR)-associated infections worldwide. This study investigated the molecular profile of MRSA in Nigeria, providing valuable genomic data to fill existing knowledge gaps and highlighting its importance in the context of the global AMR crisis. METHODS: A total of 107 isolates were obtained from patient samples, including wound swabs/pus (65 isolates, 60.7%), blood cultures (16 isolates, 15%), urine/urinary catheter (8 isolates, 7.5%) and other sources. Species identification was performed using MALDI-TOF, and antimicrobial susceptibility testing was performed using the VITEK®2 system. Genomic DNA was extracted and subjected to whole-genome sequencing using short-read Illumina technology. In addition, a subset of isolates underwent long-read sequencing using Oxford Nanopore technology. RESULTS: Among the 107 isolates, 63 (59%) were identified as MRSA, with 58 (92%) carrying the mecA gene. The MRSA isolates exhibited high resistance to non-β-lactam antibiotics, particularly trimethoprim/sulfamethoxazole (95.3%), erythromycin (76.6%), gentamicin (71.4%) and quinolones (69.8%). The most prevalent MRSA belonged to the Bengal Bay clone [t657/ST772/Staphylococcal Cassette Chromosome mec (SCCmec) V(5C2)/Panton-Valentine leukocidin (PVL) + methicillin-susceptible Staphylococcus aureus (MRSA)], followed by t4690/ST152/SCCmec Vc(5C2&5)/PVL + MRSA and ST8 (t008, n = 1; t064, n = 4)/SCCmec Vc(5C2&5). Phylogenetic analysis suggests both community/associated transmission and possible importation of strains. CONCLUSIONS: This study highlights the significant burden of MRSA in Nigeria, with the high-risk Bengal Bay MRSA clone as the most common strain. The widespread resistance to non-β-lactam antibiotics underscores the urgent need for enhanced surveillance, infection control and antibiotic stewardship to mitigate its spread.

Journal Article↗
PubMed2023

Staphylococcus aureus Prophage-Encoded Protein Causes Abortive Infection and Provides Population Immunity against Kayviruses.

Both temperate and obligately lytic phages have crucial roles in the biology of staphylococci. While superinfection exclusion among closely related temperate phages is a well-characterized phenomenon, the interactions between temperate and lytic phages in staphylococci are not understood. Here, we present a resistance mechanism toward lytic phages of the genus Kayvirus, mediated by the membrane-anchored protein designated PdpSau encoded by Staphylococcus aureus prophages, mostly of the Sa2 integrase type. The prophage accessory gene pdpSau is strongly linked to the lytic genes for holin and ami2-type amidase and typically replaces genes for the toxin Panton-Valentine leukocidin (PVL). The predicted PdpSau protein structure shows the presence of a membrane-binding α-helix in its N-terminal part and a cytoplasmic positively charged C terminus. We demonstrated that the mechanism of action of PdpSau does not prevent the infecting kayvirus from adsorbing onto the host cell and delivering its genome into the cell, but phage DNA replication is halted. Changes in the cell membrane polarity and permeability were observed from 10 min after the infection, which led to prophage-activated cell death. Furthermore, we describe a mechanism of overcoming this resistance in a host-range Kayvirus mutant, which was selected on an S. aureus strain harboring prophage 53 encoding PdpSau, and in which a chimeric gene product emerged via adaptive laboratory evolution. This first case of staphylococcal interfamily phage-phage competition is analogous to some other abortive infection defense systems and to systems based on membrane-destructive proteins. IMPORTANCE Prophages play an important role in virulence, pathogenesis, and host preference, as well as in horizontal gene transfer in staphylococci. In contrast, broad-host-range lytic staphylococcal kayviruses lyse most S. aureus strains, and scientists worldwide have come to believe that the use of such phages will be successful for treating and preventing bacterial diseases. The effectiveness of phage therapy is complicated by bacterial resistance, whose mechanisms related to therapeutic staphylococcal phages are not understood in detail. In this work, we describe a resistance mechanism targeting kayviruses that is encoded by a prophage. We conclude that the defense mechanism belongs to a broader group of abortive infections, which is characterized by suicidal behavior of infected cells that are unable to produce phage progeny, thus ensuring the survival of the host population. Since the majority of staphylococcal strains are lysogenic, our findings are relevant for the advancement of phage therapy.

Humans↗
PubMed2025

Genomic detection of Panton-Valentine Leucocidins encoding genes, virulence factors and distribution of antiseptic resistance determinants among Methicillin-resistant S. aureus isolates from patients attending regional referral hospitals in Tanzania.

BACKGROUND: Methicillin-resistant Staphylococcus aureus (MRSA) is a formidable public scourge causing worldwide mild to severe life-threatening infections. The ability of this strain to swiftly spread, evolve, and acquire resistance genes and virulence factors such as pvl genes has further rendered this strain difficult to treat. Of concern, is a recently recognized ability to resist antiseptic/disinfectant agents used as an essential part of treatment and infection control practices. This study aimed at detecting the presence of pvl genes and determining the distribution of antiseptic resistance genes in Methicillin-resistant Staphylococcus aureus isolates through whole genome sequencing technology. MATERIALS AND METHODS: A descriptive cross-sectional study was conducted across six regional referral hospitals-Dodoma, Songea, Kitete-Kigoma, Morogoro, and Tabora on the mainland, and Mnazi Mmoja from Zanzibar islands counterparts using the archived isolates of Staphylococcus aureus bacteria. The isolates were collected from Inpatients and Outpatients who attended these hospitals from January 2020 to Dec 2021. Bacterial analysis was carried out using classical microbiological techniques and whole genome sequencing (WGS) using the Illumina Nextseq 550 sequencer platform. Several bioinformatic tools were used, KmerFinder 3.2 was used for species identification, MLST 2.0 tool was used for Multilocus Sequence Typing and SCCmecFinder 1.2 was used for SCCmec typing. Virulence genes were detected using virulenceFinder 2.0, while resistance genes were detected by ResFinder 4.1, and phylogenetic relatedness was determined by CSI Phylogeny 1.4 tools. RESULTS: Out of the 80 MRSA isolates analyzed, 11 (14%) were found to harbor LukS-PV and LukF-PV, pvl-encoding genes in their genome; therefore pvl-positive MRSA. The majority (82%) of the MRSA isolates bearing pvl genes were also found to exhibit the antiseptic/disinfectant genes in their genome. Moreover, all (80) sequenced MRSA isolates were found to harbor SCCmec type IV subtype 2B&5. The isolates exhibited 4 different sequence types, ST8, ST88, ST789 and ST121. Notably, the predominant sequence type among the isolates was ST8 72 (90%). CONCLUSION: The notably high rate of antiseptic resistance particularly in the Methicillin-resistant S. aureus strains poses a significant challenge to infection control measures. The fact that some of these virulent strains harbor the LukS-PV and LukF-PV, the pvl encoding genes, highlight the importance of developing effective interventions to combat the spreading of these pathogenic bacterial strains. Certainly, strengthening antimicrobial resistance surveillance and stewardship will ultimately reduce the selection pressure, improve the patient's treatment outcome and public health in Tanzania.

Methicillin-Resistant Staphylococcus aureus↗