Panton-Valentine Leukocidin Research Articles

Genotypic insights to Panton-Valentine leukocidin positive methicillin-resistant Staphylococcus aureus isolated from cattle mastitis.

In this research communication we investigate the prevalence and antimicrobial susceptibility of S. aureus harboring virulent genes responsible for mastitis in cattle of Punjab, Pakistan. A total of 690 milk samples were collected from commercial dairy farms for analysis of the prevalence of subclinical and clinical mastitis and isolation of S. aureus. Virulence ability and methicillin resistance in S. aureus (MRSA) was determined by targeting the pvl (the gene for Panton-Valentine leukocidin) and mecA genes, respectively. A total of 175 S. aureus isolates exhibiting prevalence of pvl gene (6.28%) and mecA gene (22.28%) were determined. Antimicrobial susceptibility testing of pvl positive and negative MRSA against different classes of antibiotics revealed 100% resistance against β-lactams while 100% sensitivity towards tylosin and linezolid.

РОЛЬ МОЛЕКУЛЯРНО-ГЕНЕТИЧЕСКИХ МЕТОДОВ ИССЛЕДОВАНИЙ В ЭТИОПАТОГЕНЕЗЕ ОСТЕОМИЕЛИТА ЧЕЛЮСТЕЙ

The subject of the study is the importance of molecular genetic research methods in the study of the etiopathogenesis of osteomyelitis of the jaws. The purpose of the work is to provide up-to-date information to researchers, dental surgeons, and maxillofacial surgeons on the possibilities of molecular genetic research in identifying bacterial pathogens in osteomyelitis of the jaws, as well as to reflect genetic markers of pathogenicity factors for a number of the main causative agents of the disease. Methodology. International scientific databases PubMed, ScienceDirect, Scopus, Cochrane Collaboration, Elsevier, as well as electronic catalogs eLIBRARY.RU and CyberLeninka.ru were used. Results. A review of publications demonstrated that S. aureus and S. Epidermidis dominate the etiological spectrum of causative agents of bone tissue infections. The participation of these microorganisms is determined by a whole range of pathogenicity factors. Toxins and Panton-Valentine leukocidin (PVL) genes play a major role in the pathogenesis of osteomyelitis and disease progression. It has been shown that the pathogenic bacteria Porphyromonas gingivalis and Aggregatibacter actinomycetemcomitans are capable of inducing differentiated production of cytokines. The most attention has been attracted to E. faecium, which exhibits multidrug resistance to a wide range of antibiotics. The proportion of infections mediated by S. epidermidis and S. Saprophyticus is, on average, about 25% of cases. The proportion of representatives of gram-negative flora Escherichia, Klebsiella, Enterobacter, Citrobacter, Proteus, Providencia, Serratia reaches 23% of cases. Pathogenic nosocomial strains of P. aeruginosa are also involved in the formation of chronic inflammation in osteomyelitis. According to the results of published studies, more than a third of cases of chronic osteomyelitis are mediated by microbial associations, which are dominated by S. aureus, S. epidermidis and, less commonly, E. faecalis. Conclusions. The use of PCR analysis to identify the causative agents of osteomyelitis and gene amplification using specific primers has a huge advantage over routine microbiological tests, being an informative method for studying the pathogenicity factors of the main pathogens. The high importance of molecular genetic methods in the study of the etiopathogenesis of osteomyelitis of the jaws requires their widespread use in the clinic of surgical dentistry and maxillofacial surgery to successfully solve complex problems in the rehabilitation of patients with this disease.

Staphylococcus aureus Isolated From Traditional Artisanal Raw Milk Cheese from Southern Brazil: Diversity, Virulence, and Antimicrobial Resistance Profile

Staphylococcus aureus is one of the primary pathogenic agents found in cheeses produced with raw milk. Some strains of S. aureus are enterotoxigenic, possessing the ability to produce toxins responsible for staphylococcal food poisoning when present in contaminated foods. This study aimed to genotypically characterize, assess the antimicrobial resistance profile, and examine the enterotoxigenic potential of strains of S. aureus isolated from artisanal colonial cheese. Additionally, a bacterial diversity assessment in the cheeses was conducted by sequencing the 16S rRNA gene. The metataxomic profile revealed the presence of 68 distinct species in the cheese samples. Fifty-seven isolates of S. aureus were identified, with highlighted resistance to penicillin in 33% of the isolates, followed by clindamycin (28%), erythromycin (26%), and tetracycline (23%). The evaluated strains also exhibited inducible resistance to clindamycin, with nine isolates considered multidrug-resistant (MDR). The agr type I was the most prevalent (62%) among the isolates, followed by agr type II (24%). Additionally, ten spa types were identified. Although no enterotoxins and their associated genes were detected in the samples and isolates, respectively, the Panton-Valentine leukocidin gene (lukS-lukF) was found in 39% of the isolates. The presence of MDR pathogens in the artisanal raw milk cheese production chain underscores the need for quality management to prevent the contamination and dissemination of S. aureus strains.

Characterisation of PVL-Positive Staphylococcus argenteus from the United Arab Emirates.

Staphylococcus argenteus is a recently described staphylococcal species that is related to Staphylococcus aureus but lacks the staphyloxanthin operon. It is able to acquire both resistance markers such as the SCCmec elements and mobile genetic elements carrying virulence-associated genes from S. aureus. This includes those encoding the Panton-Valentine leukocidin (PVL), which is associated mainly with severe and/or recurrent staphylococcal skin and soft tissue infections. Here, we describe the genome sequences of two PVL-positive, mecA-negative S. argenteus sequence type (ST) 2250 isolates from the United Arab Emirates in detail. The isolates were found in a dental clinic in the United Arab Emirates (UAE). Both were sequenced using Oxford Nanopore Technology (ONT). This demonstrated the presence of temperate bacteriophages in the staphylococcal genomes, including a PVL prophage. It was essentially identical to the published sequence of phiSa2wa_st78 (GenBank NC_055048), a PVL phage from an Australian S. aureus clonal complex (CC) 88 isolate. Besides the PVL prophage, one isolate carried another prophage and the second isolate carried two additional prophages, whereby the region between these two prophages was inverted. This "flipped" region comprised about 1,083,000 bp, or more than a third of the strain's genome, and it included the PVL prophage. Prophages were induced by Mitomycin C treatment and subjected to transmission electron microscopy (TEM). This yielded, in accordance to the sequencing results, one or, respectively, two distinct populations of icosahedral phages. It also showed prolate phages which presumptively might be identified as the PVL phage. This observation highlights the significance bacteriophages have as agents of horizontal gene transfer as well as the need for monitoring emerging staphylococcal strains, especially in cosmopolitan settings such as the UAE.

Prevalence, characterization, and implications of methicillin-resistant Staphylococcus aureus (MRSA) in ready-to-eat foods from Delta, Nigeria: a concern for consumer safety

Abstract Ready-to-eat (RTE) foods are susceptible to contamination with methicillin-resistant Staphylococcus aureus (MRSA), presenting significant health risks to consumers. This study aimed to isolate, identify, and characterize MRSA from RTE foods in Delta, Nigeria, and assess their implications for consumer safety. Four hundred RTE food samples were collected from food outlets, and MRSA presence was determined using oxacillin resistance screening agar supplemented with polymyxin B and oxacillin. Polymerase chain reaction confirmed and characterized MRSA isolates for virulence potentials and antimicrobial resistance genes. Out of the 400 samples, 57(14.25%) tested positive for MRSA. The prevalence of virulence genes varied, with Panton-Valentine Leukocidin (pvl) detected in 40.51% of isolates, along with the detection of several staphylococcal enterotoxin genes. Antimicrobial resistance genes, including tetracycline (tetM, 43.04%), erythromycin (ermC, 32.91%), and methicillin (mecA, 100%; mecC, 29.11%) were detected. Staphylococcal cassette chromosome mec (SCCmec) typing revealed diverse profiles, with type V being predominant (32.9%). MRSA isolates exhibited resistance to multiple antibiotics, with 83.54% of them classified as multidrug-resistant. Extracellular virulence factors were common, with strong biofilm producers observed in 69.62% of isolates. These findings underscore the complexity of MRSA contamination in RTE foods, highlighting the need for enhanced surveillance and control measures to safeguard public health.

Lip necrosis caused by methicillin‐resistant Staphylococcus aureus (MRSA)

AbstractLabial necrosis is a rare condition with diverse causes, posing challenges for diagnosis and treatment. Methicillin‐resistant Staphylococcus aureus (MRSA) strains, particularly those positive for Panton‐Valentine leukocidin (PVL), further complicate management due to antibiotic resistance and heightened virulence. We present three cases of labial necrosis caused by MRSA, two of which resulted positive for PVL. The first case involved a 35‐year‐old male with persistent lip edema and inflammation, which progressed despite various treatments. MRSA was isolated, and the patient responded to daptomycin and clindamycin therapy. The second case featured a 38‐year‐old male with intense lip pain and swelling, initially misdiagnosed as angioedema. The patient improved after treatment with daptomycin and clindamycin, along with nasal decolonization. The third case involved a 19‐year‐old male with rapid upper lip swelling following manipulation of a boil. Prompt drainage and antibiotic treatment led to complete resolution. These cases underscore the importance of considering MRSA and PVL‐positive S. aureus as potential etiologies in labial necrosis, especially in young individuals without underlying medical conditions. Effective management involves incision and drainage, complemented by antibiotic therapy tailored to drug resistance and virulence factors.

Genomic characterization and outbreak investigations of methicillin-resistant Staphylococcus aureus in a county-level hospital in China.

Methicillin-resistant Staphylococcus aureus (MRSA) is a common pathogen contributing to healthcare-associated infections, which can result in multiple sites infections. The epidemiological characteristics of MRSA exhibit variability among distinct regions and healthcare facilities. The aim of this study was to investigate the molecular epidemiology and nosocomial outbreak characteristics of MRSA in a county-level hospital in China. A total of 130 non-repetitive MRSA strains were collected from December 2020 to November 2021. Whole-genome sequencing (WGS) was performed to identify antimicrobial resistance and virulence factors. Phylogenetic analysis was conducted to ascertain genetic diversity and phylogenetic relationships. Independent transmission scenarios were determined by the phylogeny derived from single nucleotide polymorphisms (SNPs) within the core genome. All the MRSA isolates were collected from the intensive care unit (30.00%, 39/130), the department of otorhinolaryngology (10.00%, 13/130) and the department of burn unit (9.23%, 12/130). The clinical samples mainly included phlegm (53.85%, 70/130), purulent fluid (24.62%, 32/130), and secretions (8.46%, 11/130). The resistance rates to erythromycin, clindamycin and ciprofloxacin were 75.38, 40.00, and 39.23%, respectively. All the isolates belonged to 11 clonal complexes (CCs), with the major prevalent types were CC5, CC59, and CC398, accounting for 30.00% (39/130), 29.23% (38/130), and 16.92% (22/130), respectively. Twenty sequence types (STs) were identified, and ST59 (25.38%, 33/130) was the dominant lineage, followed by ST5 (23.84%, 31/130) and ST398 (16.92%, 22/130). Three different SCCmec types were investigated, most of isolates were type IV (33.85%, 44/130), followed by type II (27.69%, 36/130) and type III (0.77%, 1/130). The common clonal structures included CC5-ST5-t2460-SCCmec IIa, CC59-ST59-t437-SCCmec IV and CC398-ST398-t034-SCCmec (-), with rates of 16.92% (22/130), 14.62% (19/130), and 13.84% (18/130), respectively. Only 12 panton-valentine leucocidin (PVL) positive strains were identified. Two independent clonal outbreaks were detected, one consisting of 22 PVL-negative strains belongs to CC5-ST5-t2460-SCCmec IIa and the other consisting of 8 PVL-negative strains belongs to CC5-ST5-t311-SCCmec IIa. Overall, our study indicated that the CC5 lineage emerged as the predominant epidemic clone of MRSA, responsible for nosocomial outbreaks and transmission within a county-level hospital in China, highlighting the necessity to strengthen infection control measures for MRSA in such healthcare facilities.

Whole genome sequencing and molecular epidemiology of methicillin-resistant Staphylococcus aureus isolated from patients with bacteraemia in Slovenia.

Data on the molecular epidemiology of methicillin-resistant Staphylococcus aureus isolates from patients with bacteraemia in Slovenia are lacking. The aim of this study was to phenotypically and genotypically investigate 82 MRSA strains isolated from patients with bloodstream infections in central Slovenia between 2019 and 2022. Whole-genome sequencing of selected strains was performed to characterize the strains based on sequence typing, antimicrobial resistance, toxin, and virulence factors genes. Most MRSA carried SCCmec II (63.4%), followed by SCCmec IV (34.1%) and SCCmec V (2.5%). A high proportion of strains belonging to the ST225 lineage (45.1%) was observed, followed by ST97 (18.3%), ST2883 (15.9%), ST22 (9.8%), ST5 (3.7%), and the ST1, ST398 and ST45 lineages (2.4% each). Sixteen different spa types were identified, predominantly ST225-t003 (31.7%), ST97-t359 (15.9%), and ST2883-t4336 (14.6%). None of the strains carried Panton-Valentine leukocidin, exfoliative toxins, or toxic shock toxin. All MRSA strains were susceptible to linezolid, rifampicin, vancomycin, teicoplanin, and trimethoprim-sulfamethoxazole. MRSA strains were resistant to erythromycin, clindamycin, tetracycline and gentamicin, with a frequency of 74.4%, 74.4%, 8.5%, and 1.2%, respectively. This study demonstrates that bacteraemia in central Slovenia is caused by diverse MRSA lineages. Identification of newly emerged lineages should be followed in the future to detect changes in the molecular epidemiology of MRSA in our country.

Antimicrobial resistance and virulence profiling of Staphylococcus pseudintermedius isolated from cats, Bangladesh

Staphylococcus pseudintermedius is a significant bacterial pathogen that frequently colonizes different body sites and mucous membranes of pets. The objectives of the cross-sectional study were to estimate the prevalence, antimicrobial resistance pattern, and detection of diverse resistance as well as virulence genes of S. pseudintermedius in cats. A standard bacteriological method, species-specific gene and different antimicrobial resistance as well as virulence genes were confirmed by PCR assay. A total of 233 swab samples were collected from different body sites of 102 cats, among them 146 swabs from 73 healthy cats, and 87 from 29 diseased cats. Overall, prevalence of S. pseudintermedius in cats was 12.01%, while dermatitis and otitis affected cats were 26.08% and 33.33%, respectively. The highest antimicrobial resistance was observed against penicillin (96.42%) followed by streptomycin (85.71%) and erythromycin (78.57%). Moreover, 89.28% of S. pseudintermedius isolates exhibit multi-drug resistance (MDR) (≥ 3 classes’ antimicrobial resistant). In addition, 17.86% isolates harbored the mecA gene; thus, were classified as methicillin-resistant S. pseudintermedius (MRSP). Furthermore, the erythromycin resistance genes ermA and ermB were harbored by 25% and 10.71% of isolates, while 42.86% and 17.86% of isolates carried tetK and tetL (tetracycline resistance) genes, respectively. In virulence profiling, 32.14% (sea) and 10.71% (seb) of isolates were found positive for enterotoxin genes, whereas, the toxic shock syndrome toxin-1 (tst-1) gene and the Panton-Valentine leukocidin gene (pvl) were detected in 25% and 14.29% of isolates, respectively. To our knowledge, this is the first report of cats in Bangladesh for MDR S. pseudintermedius, MRSP, and their virulence profiling.

Detection of Staphylococcus aureus virulence gene pvl based on CRISPR strip.

Staphylococcus aureus (S. aureus) is a prominent pathogen responsible for both hospital-acquired and community-acquired infections. Among its arsenal of virulence factors, Panton-Valentine Leucocidin (PVL) is closely associated with severe diseases such as profound skin infections and necrotizing pneumonia. Patients infected with pvl-positive S. aureus often exhibit more severe symptoms and carry a substantially higher mortality risk. Therefore, it is crucial to promptly and accurately detect pvl-positive S. aureus before initiating protective measures and providing effective antibacterial treatment. In this study, we propose a precise identification and highly sensitive detection method for pvl-positive S. aureus based on recombinase-assisted amplification and the CRISPR-ERASE strip which we previously developed. The results revealed that this method achieved a detection limit of 1 copy/μL for pvl-positive plasmids within 1 hour. The method successfully identified all 25 pvl-positive and 51 pvl-negative strains among the tested 76 isolated S. aureus samples, demonstrating its concordance with qPCR. These results show that the CRISPR-ERASE detection method for pvl-positive S. aureus has the advantages of high sensitivity and specificity, this method combines the characteristics of recombinase-assisted amplification at room temperature and the advantages of ERASE test strip visualization, which can greatly reduce the dependence on professional laboratories. It is more suitable for on-site detection than PCR and qPCR, thereby providing important value for rapid on-site detection of pvl.

Antimicrobial Resistance and the Prevalence of the Panton-Valentine Leukocidin Gene among Clinical Isolates of Staphylococcus aureus in Lithuania.

This study aimed to determine resistance to antimicrobials of Staphylococcus aureus strains isolated from clinical specimens in Lithuanian hospitals and to identify the genes conferring resistance and virulence. The study was carried out from June 2019 to September 2021. S. aureus strains were isolated from skin, soft tissues, blood, lower respiratory tract, urine and other specimens. Antibiotic susceptibility testing was performed using the disc diffusion method according to EUCAST guidelines. All isolates were analyzed for detection of the ermA, ermC, mecA, mecC, tetK, tetM, and lukF-PV genes by multiplex real-time PCR. The 16S rRNA coding sequence was applied as an internal PCR control. Altogether, 745 S. aureus strains were analyzed. Antimicrobial susceptibility testing revealed that all isolates were susceptible to rifampin and vancomycin. Of the 745 strains, 94.8% were susceptible to tetracycline, 94.5% to clindamycin, and 88.3% to erythromycin. The lowest susceptibility rate was found for penicillin (25.8%). Six percent of the tested strains were methicillin-resistant S. aureus (MRSA). The majority of methicillin-resistant strains were isolated from skin and soft tissues (73.3%), with a smaller portion isolated from blood (17.8%) and respiratory tract (8.9%). The ermC gene was detected in 41.1% of erythromycin-resistant S. aureus strains, whereas ermA was detected in 32.2% of erythromycin-resistant S. aureus strains. 69.2% of tetracycline-resistant S. aureus strains had tetK gene, and 28.2% had tetM gene. 7.3% of S. aureus isolates harbored lukF-PV gene. The frequency of the pvl gene detection was significantly higher in MRSA isolates than in methicillin-susceptible S. aureus isolates (p < 0.0001).

Evolutionary dynamics of the novel ST22-PT methicillin-resistant Staphylococcus aureus clone co-harbouring Panton–Valentine leucocidin and duplicated toxic shock syndrome toxin 1 genes

ObjectivesGlobally, the isolation of community-associated methicillin-resistant Staphylococcus aureus (MRSA) harbouring both the Panton–Valentine leucocidin (PVL) and toxic shock syndrome toxin 1 (TSST-1) genes is rare. However, we encountered an outbreak of the ST22-PT clone exhibiting this phenotype in Japan. Notably, the TSST-1 gene was duplicated in most of the strains. This study aimed to elucidate the mechanisms underlying this gene duplication. MethodsA total of 90 MRSA isolates were collected from the skin of outpatients in Fukuoka City, Japan, between 2017 and 2019. Whole-genome sequencing was performed on MRSA strains that were PVL and TSST-1 positive. ResultsA total of 43 (47.8%) strains produced TSST-1, 20 (22.2%) produced PVL, and 16 (17.8%) produced both. Fifteen isolates were classified as ST22/SCCmec type IVa (ST22-PT clone) and one as ST1/SCCmec type V (ST1-PT clone). Three distinct ST22-PT clones were identified: Fukuoka clone I (one PVL gene and one TSST-1 gene), Fukuoka clone II (addition of a TSST-1 gene to Fukuoka clone I), and Fukuoka clone III (marked by a chromosomal inversion in a large region from Fukuoka clone II). DiscussionFukuoka clone I may have integrated a novel pathogenicity island bearing the TSST-1 gene, leading to the emergence of Fukuoka clone II with a duplicated TSST-1 gene. This duplication subsequently instigated a chromosomal inversion in a large region owing to the homologous sequence surrounding TSST-1, giving rise to Fukuoka clone III. These findings provide crucial insights into the genetic evolution of MRSA.

Prevalence of Panton-Valentine leucocidin (pvl) and exfoliative toxin A (eta) gene within methicillin resistant and susceptible Staphylococcus aureus in an urban tertiary hospital: A molecular epidemiology pilot study

Background Staphylococcus aureus is well known to cause a multitude of clinical manifestations, from mild to severe bloodstream infections that could lead to death. Infections are common, either in community-acquired or hospital-acquired settings, and treatment remains a challenge due to methicillin-resistant Staphylococcus aureus (MRSA). The pathogenesis of S. aureus is mediated by several cell-surface and secreted virulence factors. The virulence factors discussed in this study are Panton-Valentine leucocidin (pvl) and exfoliative toxin A (eta). Identifying both pvl and eta gene may help in studying bacterial pathogenesis and biology thus creating possible therapeutic pathway or intervention. Our pilot study aimed to observe pvl and eta as virulence gene prevalence in a North Sumatera tertiary referral health center. Methods Our study was a descriptive-analytical observational study with a cross-sectional design in which we collected isolates over a single time period. The frequency of genes is reported as a percentage comparison between MRSA and methicillin-susceptible S. aureus (MSSA). Qualitative gene prevalence analysis was carried out using the polymerase chain reaction (PCR). Results Our results showed that from 38 MRSA sample isolates, 32 samples were found to be pvl-positive, or 84,3% of the total samples. From 40 MSSA sample isolates, one sample was found to be pvl-positive MSSA, or 97,5%. Regarding eta, from 38 MRSA sample isolates, 81,6% of the total sample did not have eta, while from 40 MSSA sample isolates, all samples were found to be positive for eta. We found that both pvl and eta were significantly more likely to be expressed in the MSSA strain. Conclusions Our study shows that pvl and eta are more likely expressed in MSSA strains than in MRSA strains in Indonesia.

Staphylococcal scalded skin syndrome in neonate: Another face of CA-MRSA.

Staphylococcal scalded skin syndrome (SSSS), also known as Ritter's disease, in its severe form occurs predominantly in infants and children. It is caused by infection with group II (often phage group 71) Staphylococcus aureus. The foci of infection include nasopharynx, less commonly umbilicus, urinary tract, superficial abrasion, conjunctivae, and blood. Staphylococci are non-motile, non-spore-forming, catalase-positive, gram-positive cocci that appear predominantly as grape-like clusters. Although this organism is frequently a part of normal human microbial flora, it can cause significant opportunistic infections under certain conditions such as when extremes of age groups are involved, the presence of indwelling medical devices, and intravenous (iv) drug abuse. Staphylococcus aureus may cause a variety of infectious manifestations ranging from relatively benign skin infections to life-threatening systemic illnesses. SSSS caused by S. aureus strains produces exfoliative toxins which result in the development of blisters, erythema, and desquamation. Here, we present a case of an 11-day-old neonate who was diagnosed with SSSS. The causative agent responsible for this syndrome was identified as methicillin-resistant Staphylococcus aureus (MRSA). The molecular characterization of the gene Panton-Valentine leukocidin (PVL) was done by polymerase chain reaction (PCR) and was detected positive for PVL which is a distinctive virulence factor seen almost in all of the community-acquired MRSA strains. The patient was discharged after parenteral clindamycin therapy with almost complete resolution of symptoms.

Epidemiology and clinical features of Skin and Soft Tissue Infections Caused by PVL-Positive and PVL-Negative Methicillin-Resistant Staphylococcus aureus Isolates in inpatients in China: a single-center retrospective 7-year study

ABSTRACT Previous studies have mainly focused on outpatient cases of skin and soft tissue infections (SSTIs), with limited attention to inpatient occurrences. Thus, we aimed to compare the clinical parameters of inpatients with SSTIs, performed genomic characterization, and determined the subtypes of Panton-Valentine leucocidin (PVL) bacteriophages of methicillin-resistant Staphylococcus aureus (MRSA) strains isolated from these patients. We found that PVL-positive patients had shorter hospital stays (mean, 9 vs. 24 days; p < 0.001) and abscess resolution durations (mean, 8 vs. 13 days; p < 0.01). PVL-positive MRSA-induced SSTIs were more frequently associated with abscesses [36/55 (65.5%) vs. 15/124 (12.1%), p < 0.001], with 52.7% undergoing incision and drainage; over 80% of PVL-negative patients received incision, drainage, and antibiotics. In PVL-positive patients receiving empirical antibiotics, anti-staphylococcal agents such as vancomycin and linezolid were administered less frequently (32.7%, 18/55) than in PVL-negative patients (74.2%, 92/124), indicating that patients with PVL-positive SSTIs are more likely to require surgical drainage rather than antimicrobial treatment. We also found that the ST59 lineage was predominant, regardless of PVL status (41.3%, 74/179). Additionally, we investigated the linear structure of the lukSF-PV gene, revealing that major clusters were associated with specific STs, suggesting independent acquisition of PVL by different strain types and indicating that significant diversity was observed even within PVL-positive strains detected in the same facility. Overall, our study provides comprehensive insights into the clinical, genetic, and phage-related aspects of MRSA-induced SSTIs in hospitalized patients and contributes to a more profound understanding of the epidemiology and evolution of these pathogens in the Chinese population.

Clinical impact and public health challenges of a PVL-MRSA bacteraemia outbreak amongst people who inject drugs in South Yorkshire, UK.

Panton-Valentine leukocidin (PVL) Staphylococcus aureus (SA) is an emergent public health concern. PVL toxin has been mostly associated with methicillin-sensitive S. aureus (MSSA)-related skin and soft tissue infections occurring in high-risk groups such as people who inject drugs (PWID). The emergence of PVL methicillin-resistant S. aureus (MRSA) infection is causing severe and life-threatening disease in PWID. We present an outbreak of eight PVL-MRSA bacteraemia cases at a UK teaching hospital between 2018 and 2022. An additional four patients developed bacteraemia with PVL-negative MRSA of the same multilocus sequence type (MLST). All patients were PWID and aged 33-51 years old. Four patients developed MRSA bacterial endocarditis. Three patients died. These cases represent the initial cases detected at Doncaster and Bassetlaw Teaching Hospitals of what is an ongoing and developing outbreak. An outbreak investigation has been undertaken in association with the UK Health Security Agency. Epidemiological factors have been explored, including via direct contact at a local sheltered accommodation and the possibility of a contaminated drug supply. Whole-genome sequencing confirmed that all isolates were closely related and of the same MLST (sequence type 5). A community substance misuse group disseminated health education on the prevention of PVL-MRSA. Preventing infection in PWID presents a major challenge due to the impact of addiction on engagement with services and the significant barriers faced by our patients in observing infection prevention measures. PVL-MRSA is of major public health concern and outbreak investigation and mapping out local epidemiological patterns plays a vital role in preventing further spread throughout the community. Additionally, this work enables targeted and early treatment in patients in high-risk categories for disease. These cases of PVL-MRSA infection in PWID highlights the transmissibility, pathogenic potential and severe clinical disease spectrum within this population. Further work is required to tackle transmission and infection from this pathogenic strain.

Computational Study of Antimicrobial Peptides for Promising Therapeutic Applications Against Methicillin-resistant Staphylococcus Aureus.

Methicillin-resistant Staphylococcus aureus (MRSA) is a causative agent for multiple drug-resistant diseases and is a prime health concern. Currently, antibiotics like vancomycin, daptomycin, fluoroquinolones, linezolid, fifth-generation cephalosporin and others are available in the market for the treatment of MRSA infection. With the increasing prevalence of drug-resistant cases, researchers are actively investigating alternative strategies to combat MRSA, including the exploration of peptide therapeutics. This study employed computational methods to prospect for potential Antimicrobial Peptides (AMPs). A total of One hundred and fifty antimicrobial peptides were explored based on physicochemical properties. The results showed that Clavanin B was the most appropriate candidate. Molecular Docking and Molecular Dynamics Simulation results showed the protein-peptide interaction of the MRSA target proteins, Penicillin Binding Protein 2a and Panton-Valentine Leukocidin Toxin, with the Antimicrobial Peptide Clavanin B. Currently, the antimicrobial peptide database highlights Clavanin B's role as an anti-HIV peptide. Moreover, this investigation proposes Clavanin B as a viable repurposed drug for treating MRSA, underscoring its potential deployment in the management of MRSA infections.

Staphylococcus aureus Panton-Valentine Leukocidin worsens acute implant-associated osteomyelitis in humanized BRGSF mice.

Staphylococcus aureus is the most common pathogen that causes implant-associated osteomyelitis, a clinically incurable disease. Immune evasion of S. aureus relies on various mechanisms to survive within the bone niche, including the secretion of leukotoxins such as Panton-Valentine leukocidin (PVL). PVL is a pore-forming toxin exhibiting selective human tropism for C5a receptors (C5aR1 and C5aR2) and CD45 on neutrophils, monocytes, and macrophages. PVL is an important virulence determinant in lung, skin and soft tissue infections. The involvement of PVL in S. aureus pathogenesis during bone infections has not been studied extensively yet. To investigate this, humanized BALB/c Rag2-/-Il2rg-/-SirpaNODFlk2-/- (huBRGSF) mice were subjected to transtibial implant-associated osteomyelitis with community-acquired methicillin-resistant S. aureus (CA-MRSA) USA300 wild type strain (WT), an isogenic mutant lacking lukF/S-PV (Δpvl), or complemented mutant (Δpvl+pvl). Three days post-surgery, Δpvl-infected huBRGSF mice had a less severe infection compared to WT-infected animals as characterized by 1) improved clinical outcomes, 2) lower ex vivo bacterial bone burden, 3) absence of staphylococcal abscess communities (SACs) in their bone marrow, and 4) compromised MRSA dissemination to internal organs (liver, kidney, spleen, heart). Interestingly, Δpvl-infected huBRGSF mice had fewer human myeloid cells, neutrophils, and HLA-DR+ monocytes in the bone niche compared to WT-infected animals. Expectedly, a smaller fraction of human myeloid cells were apoptotic in the Δpvl-infected huBRGSF animals. Taken together, our study highlights the pivotal role of PVL during acute implant-associated osteomyelitis in humanized mice.

Molecular detection of pore-forming leuko toxin in methicillin resistant Staphylococcus aureus isolated from skin infection

Abstract Background: The ability of Staphylococcus aureus to cause disease has been attributed to an impressive spectrum of virulence factors. Objective: The study investigated molecular detection of pore-forming leuko toxin (Panton–Valentine leucocidin [PVL]) in S. aureus that is resistant to methicillin (MRSA) isolated from skin infections. Materials and Methods: All 100 isolates of S. aureus were obtained from clinical samples (burn, wound, impetigo, boil, acne, abuses, folliculated, infected atopic dermatitis, and secondary infection), and 24 of these had been confirmed as MRSA. Antibiotic susceptibility patterns, mecA, 16sRNA, and PVL genes were isolated and detected by polymerase chain reaction (PCR). Results: All isolates were determined to be resistant to cefoxitin discs and oxacillin by using phenotypic analysis, and a genotypic investigation revealed that 79.16% of them carried the mecA gene. Additionally, the data showed that 58.33% of MRSA isolates contain the PVL gene and 83.33%% of MRSA isolates harbor of 16sRNA gene. Conclusions: The study detected a high S. aureus isolates percentage in a burn, followed by impetigo, wound, and boil, respectively. A higher percentage of MRSA isolates contain the PVL gene, mecA, and harbor of 16sRNA gene.

Antimicrobial resistance profile of Staphylococcus aureus isolated from patients, healthcare workers, and the environment in a tertiary hospital in Addis Ababa, Ethiopia.

Staphylococcus aureus infection and colonization in patients may be transmitted to healthcare providers and the environment and subsequently cause healthcare-associated infections in other patients. Pathogenic S. aureus strains produce virulence factors, such as Panton-Valentine Leukocidin (PVL), that contribute to the severity of infections and aid in their spread. The emergence of antimicrobial resistance (AMR) is additional concern with respect to S. aureus infection. In this study, the virulence genes and antibiotic resistance profiles of S. aureus were characterized from patients' clinical isolates, healthcare workers' (HCWs') nasal colonization screenings, and the environment at a tertiary healthcare hospital in Addis Ababa, Ethiopia. A total of 365 samples were collected from September 2021 to September 2022: 73 patients' clinical specimens, 202 colonization screenings from HCWs, and 90 hospital environment's swabs. Fifty-one (25.2%) HCW and 10/90 (11.1%) environment S. aureus isolates were identified. Among the 134 isolates, 10 (7.5%) were methicillin-resistant S. aureus (MRSA). Three (4.1%), five (9.8%), and two (20.0%) of the MRSA isolates were identified from the patients, HCWs, and the environment, respectively. Overall, 118 (88.1%) were ampicillin and penicillin resistant; 70 (52.2%) were trimethoprim sulfamethoxazole resistant; and 28 (20.9%) were erythromycin resistant. S. aureus isolates from patients were more resistant to antibiotics than isolates from HCWs or the hospital environment (p<0.05). A total of 92/134 (68.6%) isolates possessed the lukfF-PV gene, which was identified in 62 (85.0%), 26 (51.0%), and 4 (40.0%) of the patient, HCWs, and the environment, respectively. The proportion of lukfF-PV gene containing S. aureus isolated from patient samples was statistically significant. Four (40.0%) of the MRSA isolates also had the lukfF-PV gene. The identification of highly AMR and virulence factors from patients, HCWs and the environment is concerning. Further studies are needed to identify potential transmission links and improve infection prevention and control.