Panton-Valentine Leukocidin Genes 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.

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.

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).

Diversity of Staphylococcus aureus isolated from nares of ruminants.

To examine the diversity of Staphylococcus aureus isolated from nasal swabs of ruminants in Rwanda. A total of 454 nasal swabs from 203 cows, 170 goats, and 81 sheep were examined for the presence of S. aureus, and 30 S. aureus isolates were detected and characterized pheno- and genotypically. Resistance to penicillin and/or tetracycline was observed. The isolates were assigned to eight different spa types (t21057 (novel), t10103, t18853, t20842, t318, t355, t458, and t9432) belonging to six clonal complexes (CCs) (CC152, CC30, CC3591, CC3666, CC522, and CC97). Panton-Valentine leukocidin (PVL) genes (lukF-PV/lukS-PV), the bovine leukocidin genes (lukM/lukF-P83), and the human and bovine variants of the toxic shock syndrome toxin gene tst-1 variants were detected. These findings demonstrate that the nares of ruminants in Rwanda are colonized with mastitis-associated S. aureus, including lineages that are also carried by humans, underscoring the zoonotic risk, especially for livestock keepers. These results highlight the crucial importance of hygiene measures when handling livestock.

A Rare Case of Panton-Valentine Leukocidin-Related Cervical Empyema

Abstract Staphylococcus aureus is found in the normal skin and mucosa of approximately 30% of healthy populations and is the most common pathogen in human disease associated with bacteria. They are divided into methicillin-sensitive S. aureus (MSSA) and methicillin-resistant S. aureus (MRSA). The S. aureus strains carrying the Panton-Valentine leukocidin genes (SA-PVL) were initially believed to belong to the MRSA group; however, recent reports showed they also belonged to the MSSA group (MSSA-PVL). SA-PVL is common in skin and soft-tissue infections but rare in musculoskeletal infections, especially in spondylodiscitis. We are reporting a case suffering from cervical spondylodiscitis and epidural abscess associated with MSSA carrying the Panton-Valentine leukocidin genes.

Genetic characterization of methicillin-resistant / susceptible Staphylococcus aureus (MRSA/MSSA) and Staphylococcus argenteus clinical isolates in Bangladesh: Dominance of ST6-MRSA-IV/t304 and detection of cfr/fexA in ST8-MSSA/t008

ObjectivesCoagulase-positive staphylococcus (CoPS), represented by Staphylococcus aureus, is a major cause of infections in humans. This study aimed to investigate molecular epidemiological characteristics, antimicrobial resistance, and their trends of CoPS in Bangladesh. MethodsClinical isolates of CoPS were collected from two medical institutions in Bangladesh for a 2-year period and analyzed for their species, genotypes, virulence factors, antimicrobial susceptibility, and resistance determinants. Results172 CoPS isolates collected were identified as S. aureus or S. argenteus (170 and two, respectively). Methicillin-resistant S. aureus (MRSA) accounted for 36% (n = 61), having Staphylococcal cassette chromosome mec (SCCmec)-IV (82%) or V (18%). Panton-Valentine leukocidin (PVL) genes were detected at higher rate in methicillin-susceptible S. aureus (MSSA) (62%) than MRSA (26%). MRSA comprised 11 STs, including a dominant type ST6 (46%) associated with mostly SCCmec-IVa/spa-t304, and one isolate had genetic features of the USA300 clone (ST8/SCCmec-IVa/coa-IIIa/spa-t008/ACME-I/ΦSa2USA). STs of CC1, CC88, and CC398 were common in MSSA, with CC88 showing the highest PVL-positive rate. One MSSA isolate (ST8/spa-t008) harbored fexA and cfr showing susceptibility to linezolid. S. argenteus was methicillin-susceptible and belonged to ST2250/coa-XId. ConclusionsGenetic characteristics of current MRSA/MSSA in Bangladesh were revealed, with first identification of S. argenteus at low prevalence.

A Study of Community-Acquired Pyodermas with Special Reference to Panton-Valentine Leukocidin (PVL)-Positive Methicillin-Resistant Staphylococcus Aureus.

Community-acquired (CA) pyodermas are one of the most common infections encountered in the dermatology outpatient clinics. A significant number of these conditions are caused by Staphylococcus aureus. CA-methicillin-sensitive Staphylococcus aureus (MSSA) and CA-methicillin-resistant Staphylococcus aureus (MRSA) have specific virulence genes which are associated with these diseases, particularly the Panton-Valentine leukocidin (PVL) genes. The presence of the PVL gene as a virulence factor may be associated with recurrent and severe skin infections. A prospective study was conducted with 205 cases of CA pyodermas, of which five were discarded due to mixed isolates. Clinical details were taken and wound exudate was sent for bacteriological examination. Further, the molecular study was performed on all MRSA (7) isolates and 13 randomly selected MSSA isolates using polymerase chain reaction for mecA and PVL genes. Staphylococcus aureus was the most common organism (90%) isolated from primary or secondary CA pyodermas. The prevalence of CA-MRSA among all pyodermas was 3.5% in our community. The PVL gene was not detected in all tested CA-MRSA and CA-MSSA isolates. While pyodermas are common, the prevalence of MRSA is low in the CA pyodermas in our region. PVL does not appear to be a virulence factor among the isolated MRSA. Larger, multicentric, and periodic studies are, however, required to further justify these claims.

Impact of human created environments in the pathogenic potential and antimicrobial resistance of staphylococci from wild neotropical primates in Brazil

The non-human primate (NHP) Leontopithecus rosalia is an endangered species native of Brazil and lives in forest fragments with different levels of contact with humans (natural, private and urban). Other NHPs – Callithrix spp. - were introduced by humans and co-exist and interact with the native species in these forests.To evaluate if living in or close to human-modified environments could constitute a risk for L. rosalia, we compared the prevalence, genetic background, antibiotic susceptibility and virulence gene content of staphylococci collected from the native and the introduced species from different forest fragments.We found that presence in human-dominated environments increased the colonization rate of L. rosalia with Mammaliicoccus sciuri (former Staphylococcus sciuri) from 18 % to 85 % (p = 0.0001) and of Callithrix spp with Staphylococcus aureus from 6 % to 100 % (p = 0.0001). According to molecular typing data obtained differences probably resulted from dissemination of these bacterial species from the invader NHP species and from humans. Changes in microbiota were paralleled by an increase in the prevalence of Panton-Valentine Leukocidin gene and in resistance to beta-lactams, macrolides and/or lincosamides as exposure to human environment increased. In particular, erythromycin resistance in S. aureus from Callithrix spp. increased from 0 % to 50 % and resistance rate to at least one antibiotic in coagulase-negative staphylococci species from L. rosalia increased from 13 % to 56 % (p = 0.0003).Our results showed that contact of native animal species with human-created environments increased the content of antimicrobial resistant and pathogenic bacteria on their commensal microbiota, which ultimately can impact on their health. ImportanceEndangered animal species are vulnerable to environmental alterations and human activities have been repeatedly identified as factors driving drastic changes in the natural landscape. It is extremely important to monitor changes in the environment surrounding protected species, because this could lead to early detection of any potential threats. In this study, we found that the contact of L. rosalia - a protected non-human primate from Brazil - with human environments is related to changes in their commensal microbiota. These included an increase in the number of pathogenic and antibiotic resistant bacteria, which have a higher potential to cause infections that are more difficult to treat. We provided evidence for the harmful impact human contact has on L. rosalia. Also, our results suggest that monitoring of commensal microbiota of protected animal species might be a useful way of sensing the risks of protected species to human exposure.

Significant increase in the prevalence of Panton–Valentine leukocidin-positive methicillin-resistant Staphylococcus aureus , particularly the USA300 variant ΨUSA300, in the Japanese community

ABSTRACT USA300, a major Panton–Valentine leukocidin (PVL)-producing methicillin-resistant Staphylococcus aureus (MRSA) clone associated with skin and soft tissue infections (SSTIs), carries a type IV staphylococcal cassette chromosome mec (SCC mec ) element. Recently, a USA300 variant, ΨUSA300, with a 12-bp deletion of ccrB2 in the SCC mec element, was identified in Japan by Takadama et al. (15). To understand the current status of PVL-positive MRSA in the community, a nationwide surveillance of MRSA isolated from outpatients at dermatology departments was conducted. This study included 1,619 outpatients who visited dermatology departments at 22 healthcare facilities in 11 prefectures in Japan between 2018 and 2021; S. aureus were isolated from these outpatients. Molecular epidemiological analysis was performed using PCR, SCC mec and spa typing, pulsed-field gel electrophoresis, multilocus sequence typing, and antimicrobial susceptibility testing. A total of 980 S . aureus were isolated, 293 of which were identified as MRSA. Among MRSA isolates, PVL genes were detected in 18 of 63 (28.6%) in 2018, 34 of 85 (40.0%) in 2019, 29 of 65 (44.6%) in 2020, and 40 in 80 (50.0%) in 2021. Among the PVL-positive MRSA, 16 of 121 (13.2%) and 94 of 121 (77.7%) isolates were identified as USA300 and ΨUSA300, respectively. ΨUSA300 strains were collected from six prefectures in Japan: Kagawa, Osaka, Tokyo, Kanagawa, Fukushima, and Saitama. ΨUSA300 was isolated more frequently than USA300 from patients with deep-seated SSTIs ( P &lt; 0.05). Our findings showed that PVL-positive MRSA isolates were significantly increased in the Japanese community. Furthermore, the USA300 variant ΨUSA300 has emerged as the predominant PVL-positive MRSA clone across the Kanto, Kinki, and Shikoku regions of Japan, and this variant may possess a greater propensity to cause deep-seated SSTIs than in USA300. IMPORTANCE USA300 is an MRSA clone producing PVL, a toxin associated with SSTIs. ΨUSA300 is a USA300 variant recently identified in Japan by Takadama et al. (15). Here, we found that the prevalence rate of PVL-positive MRSA in S. aureus was elevated in the Japanese community, and ΨUSA300 accounted for most of them. ΨUSA300 strains have been isolated from several areas in Japan and were associated with deep-seated SSTIs. This study highlighted the emerging threat posed by ΨUSA300 in Japan.

Panton-Valentine Leukocidin (PVL) genes may not be a reliable marker for community-acquired MRSA in the Dakahlia Governorate, Egypt

BackgroundMethicillin-resistant Staphylococcus aureus is linked to both nosocomial and community infections. One of the key virulence factors of S. aureus is Panton-Valentine leukocidin (PVL). The PVL genes are mostly associated with community-acquired MRSA (CA-MRSA). This study evaluates the prevalence of PVL genes as a marker for CA-MRSA at tertiary hospitals in Mansoura, Dakahlia, Egypt. S. aureus was isolated from clinical specimens obtained from different departments of tertiary hospitals, outpatient clinics, and hospital healthcare workers (HCWs). PCR was used to detect the mecA, PVL, and SCCmec genes among the recovered isolates. Standard broth microdilution method was used to determine the minimum inhibitory concentrations (MIC) of nine antibiotics against S. aureus.ResultsTwo hundred S. aureus isolates were recovered and identified out of the total isolates (n = 320). The mecA gene was detected in 103 S. aureus isolates (51.5%). Among the MRSA isolates, 46.60% were PVL-positive. The incidence of the PVL genes of MRSA in nosocomial (HA), outpatient clinics (CA), and HCWs was 46.66%, 56.52%, and 42%, respectively. All MRSA isolates showed resistance to cefoxitin. The percentage of resistance to most tested antibiotics was high, except for ciprofloxacin (6.85%). Both antibiotic resistance and multidrug resistance among MRSA isolates were generally higher in PVL-positive isolates than in PVL-negative isolates in HA- and CA-MRSA isolates. While SCCmec type V was the most prevalent in PVL-positive MRSA stains, type I was the most prevalent in PVL-negative isolates.ConclusionThis study revealed that PVL genes are generally highly prevalent among mecA-positive MRSA isolates, whether they are CA-MRSA, HA-MRSA, or HCW isolates. Therefore, PVL is not a valid marker for CA-MRSA in Mansoura, Dakahlia Governorate, Egypt, as has been reported in other countries. Further epidemiologic studies are required to track the incidence of PVL in HA-MRSA, CA-MRSA, and HCW isolates in other Egyptian governorates.

Reduction of Panton-Valentine Leukocidin Production in the Staphylococcal Strain USA300 After In Vitro Ascorbic Acid and Nicotinamide Treatment.

Background Panton-Valentine leukocidin (PVL) is one of the most important determinants of virulence in Staphylococcus aureus. It is associated with a propensity for complicating skin and soft tissue infections and necrotizing pneumonia. This study aims to quantitively examine the effect of ascorbic acid and nicotinamide on PVL production in the reference strain USA300. Methodology Sandwich enzyme-linked immunosorbent assay (ELISA) was used to quantitively measure the production of PVL via the commercial LukS sandwich ELISA kit (IBT Bio-services, MD, USA). Results Incubating USA300 with subinhibitory concentrations of antioxidants resulted in a statistically significant eight-fold reduction in PVL production at 1.25 mg/mL and 30 mg/mL for ascorbic acid and nicotinamide, respectively. Although the mechanism by which antioxidants inhibit PVL production is yet to be elucidated, we suggest that it can be due to interrupting PVL gene expression. Conclusions Ascorbic acid and nicotinamide have the potential to be toxin-suppressing agents that may be effective in supporting the bactericidal effect of antibiotics to improve the outcome of PVL-associated infections; however, further extensive research is required.

DETECTION OF PANTON-VALENTINE LEUKOCIDIN (PVL) GENE AGAINST METHICILLIN-RESISTANT STAPHYLOCOCCUS AUREUS (MRSA) IN DIABETIC ULCER PATIENTS

Background: Diabetes Mellitus (DM) patients are susceptible to wound infections brought on by S. aureus bacteria, in dealing with infections caused by bacteria, antibiotic treatment was conducted. Nevertheless, misapplication of antibiotics might lead to drug resistance or MRSA. Panton-Valentine Leukocidin (PVL) is a crucial factor of S. aureus pathogenicity. Skin and soft tissue infections can be caused by the PVL gene. Purpose: To detect PVL gene in ulcer swabs of diabetic mellitus patients against MRSA strains. Method: Employing descriptive quantitative data analysis of PVL gene detection observations on ulcer swab of diabetes mellitus patients using the RT-PCR method. Ulcer swab samples were collected at Dharmahusada and Banyu Urip Diabetes Wound Specialist Hospital, Surabaya, East Java, Indonesia. The research was conducted at the Department of Medical Laboratory Technology, Health Polytechnic Ministry of Health Surabaya, Bacteriology Laboratory for the isolation and identification of MRSA and Molecular Biology Laboratory for the detection of the PVL gene in April–May 2022. Result: From 30 samples of ulcer swabs, 8 samples were positive for MRSA and 22 samples were negative for MRSA. After that, the MRSA positive samples were detected using the RT-PCR method to detect the PVL gene. The results of PVL detection were obtained from 6 samples (75%) positive for detecting the PVL gene and 2 samples (25%) negative for detecting the PVL gene. Conclusion: The results of the study showed that ulcer swabs from diabetes mellitus patients had the PVL gene against MRSA.

Antibiotic susceptibility and clonal distribution of Staphylococcus aureus from pediatric skin and soft tissue infections: 10-year trends in multicenter investigation in China.

Skin and Soft Tissue Infections (SSTIs) Surveillance Network of S. aureus In Pediatrics in China was established in 2009 to routinely report epidemiological changes. We aimed to monitor the present antibiotic sensitivity and molecular characteristics of S. aureus and methicillin-resistant S. aureus (MRSA) from SSTIs in children nationwide and track the changes over the past decade. Patients diagnosed with SSTIs from the dermatology departments of 22 tertiary pediatric hospitals in seven geographical regions of China were recruited continuously from May 2019 to August 2021. S. aureus was isolated, and its sensitivity to 15 antimicrobials was evaluated using the broth microdilution method. The molecular characteristics of the MRSA isolates were determined through multilocus sequence typing (MLST) and staphylococcal cassette chromosome mec (SCCmec) typing. The presence of the Panton-Valentine leukocidin gene (pvl) was determined. The detection rate of S. aureus was 62.57% (1379/2204), among which MRSA accounted for 14.79% (204/1379), significantly higher than the result in previous study in 2009-2011 (2.58%, 44/1075). Compared with previous study, the sensitivity to cephalosporins and fusidic acid decreased to varying degrees, while that to chloramphenicol, ciprofloxacin, clindamycin, erythromycin, gentamicin, penicillin, and tetracycline increased significantly. The sensitivity to mupirocin, trimethoprim/sulfamethoxazole (TRISUL), and rifampicin still maintained at a high level (97.90%, 99.35% and 96.66% respectively). The leading multidrug resistance pattern of MRSA and methicillin-sensitive S. aureus (MSSA) were erythromycin-clindamycin-tetracycline (55.84%; 43/77) and erythromycin-clindamycin-chloramphenicol (27.85%, 44/158) respectively. 12 high-level mupirocin-resistant strains were detected, and notable differences in geographical distribution and seasonal variation were observed. The main types of MRSA were ST121 (46.08%, 94/204), followed by ST59 (19.61%, 40/204). SCCmec V (65.69%, 134/204) and SCCmec IV (31.86%, 65/204) were dominant epidemic types. ST121-V, ST59-IV, and ST22-V were the most prevalent clones nationwide. The detection rate of pvl had increased markedly from 9.09% (4/44) in 2009-2011 to 22.55% (46/204) in 2019-2021 (P<0.05). The antibiotic sensitivity and molecular characteristics of S. aureus from pediatric SSTIs has changed significantly over the past decade. To standardize medical care, provide timely and reasonable clinical treatment, and effectively manage infection control, Chinese pediatric SSTIs guidelines are urgently needed.

Acute Prosthetic Joint Infections with Poor Outcome Caused by Staphylococcus Aureus Strains Producing the Panton-Valentine Leukocidin.

The aim of this study was to investigate whether the presence of Staphylococcus aureus (SA) producing the Panton-Valentine leukocidin (PVL) affects the outcome of Prosthetic Joint Infection (PJI). Patients with acute and chronic PJI sustained by SA were prospectively enrolled at the orthopedic unit of "Casa di Cura Santa Maria Maddalena", from January 2019 to October 2021. PJI diagnosis was reached according to the diagnostic criteria of the International Consensus Meeting on PJI of Philadelphia. Synovial fluid obtained via joint aspirations was collected in order to isolate SA. The detection of PVL was performed via real-time quantitative PCR (RT-qPCR). The outcome assessment was performed using the criteria of the Delphi-based International Multidisciplinary Consensus. Twelve cases of PJI caused by SA were included. Nine (75%) cases were acute PJI treated using debridement, antibiotic and implant retention (DAIR); the remaining three (25%) were chronic PJI treated using two-stage (n = 2) and one-stage revision (n = 1), respectively. The SA strains that tested positive for PVL genes were 5/12 (41.6%,). Treatment failure was documented in three cases of acute PJI treated using DAIR, all supported by SA-PVL strains (p < 0.045). The remaining two cases were chronic PJI treated with a revision arthroplasty (one and two stage, respectively), with a 100% eradication rate in a medium follow-up of 24 months. Although a small case series, our study showed a 100% failure rate in acute PJI, probably caused by SA PVL-producing strains treated conservatively (p < 0.04). In this setting, toxin research should guide radical surgical treatment and targeted antibiotic therapy.

Clonal Complexes Distribution of Staphylococcus aureus Isolates from Clinical Samples from the Caribbean Islands.

The aim of this study was to comprehensively characterise S. aureus from the Caribbean Islands of Trinidad and Tobago, and Jamaica. A total of 101 S. aureus/argenteus isolates were collected in 2020, mainly from patients with skin and soft tissue infections. They were characterised by DNA microarray allowing the detection of ca. 170 target genes and assignment to clonal complexes (CC)s and strains. In addition, the in vitro production of Panton-Valentine leukocidin (PVL) was examined by an experimental lateral flow assay. Two isolates were identified as S. argenteus, CC2596. The remaining S. aureus isolates were assigned to 21 CCs. The PVL rate among methicillin-susceptible S. aureus (MSSA) isolates was high (38/101), and 37 of the 38 genotypically positive isolates also yielded positive lateral flow results. The isolate that did not produce PVL was genome-sequenced, and it was shown to have a frameshift mutation in agrC. The high rate of PVL genes can be attributed to the presence of a known local CC8-MSSA clone in Trinidad and Tobago (n = 12) and to CC152-MSSA (n = 15). In contrast to earlier surveys, the USA300 clone was not found, although one MSSA isolate carried the ACME element, probably being a mecA-deficient derivative of this strain. Ten isolates, all from Trinidad and Tobago, were identified as MRSA. The pandemic ST239-MRSA-III strain was still common (n = 7), but five isolates showed a composite SCCmec element not observed elsewhere. Three isolates were sequenced. That showed a group of genes (among others, speG, crzC, and ccrA/B-4) to be linked to its SCC element, as previously found in some CC5- and CC8-MRSA, as well as in S. epidermidis. The other three MRSA belonged to CC22, CC72, and CC88, indicating epidemiological connections to Africa and the Middle East.

Molecular Characteristics of Staphylococcus aureus Strains to Carry Panton-Valentine Leukocidin Genes Isolated from Hospitalized Patients in Tehran, Iran

Background: Staphylococcus aureus with concurrent resistance to antibacterial agents is emerging globally. This emergence might be due to the production of different virulence determinants, notably Panton-Valentine leukocidin (PVL). Objectives: This study aimed to investigate the genetic characteristics of PVL-positive S. aureus strains isolates from clinical samples. Methods: An epidemiological study was conducted on 65 S. aureus isolates carrying pvl genes. An antibiogram test by the disk diffusion and broth microdilution methods was conducted to assess antimicrobial resistance profiles. Results: All detected methicillin-resistant S. aureus (MRSA) isolates were confirmed by mecA polymerase chain reaction (PCR) assays. The PVL-positive isolates were characterized using multiplex PCR assay to detect staphylococcal cassette chromosome mec (SCCmec) and agr types. The PVL frequency was 19.5% and 17.6% in MRSA and methicillin-susceptible S. aureus (MSSA), respectively. Among the PVL-positive isolates, 66.2% and 33.8% were MRSA and MSSA, respectively. Multidrug resistance amounted to 84.6% of the isolates (MRSA: 61.5%, MSSA: 23.1%). Staphylococcal cassette chromosome mec III was dominated (55.8%; 24/43). The most commonly identified agr was type III (53.8%; 35/65). Resistance to vancomycin amounted to 12.3% of the isolates, and all belonged to agr type III and SCCmec type III. The frequency of inducible and constitutive clindamycin resistance among PVL-positive MRSA strains (12.3% and 26.1%) was higher than PVL-positive MSSA strains (7.7% and 15.4%). Most constitutive and inducible clindamycin resistance isolates belonged to agr type III (26.2% and 18.5%) and SCCmec type III (each 27.9%). In the present study, 32.3% of the isolates were confirmed as mupirocin resistant, and all were MRSA, 9 (42.9%) and 12 (57.1%) isolates of which exhibited high-level mupirocin resistant (HLMUPR) and low-level mupirocin resistant phenotypes. All HLMUPR MRSA isolates belonged to SCCmec III and recovered from wound samples. Conclusions: The emergence of vancomycin-resistant S. aureus strains among PVL-positive S. aureus strains in Iran is a serious alarm and seems to be becoming the greatest concern in the treatment of staphylococcal infections in the healthcare setting. The present study reinforces plausible direct transfers between community and nosocomial PVL-positive S. aureus types.

Bacteriological Profile of Chronic Rhinosinusitis and Adenotonsillitis: Evaluating the Role of Biofilm Production and Multidrug Resistance.

There is significant evidence that the etiology of chronic otorhinolaryngology infections such as chronic rhinosinusitis, adenotonsillitis, and otitis media depends on biofilms. As biofilm-forming bacteria can be resistant to the immune system, antibiotics, and other treatments, biofilm infections are often chronic. To identify the genus and species of the clinical isolates obtained from the swabs collected from the patients with chronic infections of the nasal and paranasal sinus, nasopharynx, and oropharynx and to evaluate phenotypic and genotypic methods for the detection of biofilms and antimicrobial resistance among the isolated organisms. A total of 100 patients with chronic rhinosinusitis and adenotonsillitis participated in this study. Various clinical samples from the nasal cavity, nasopharynx, and oropharynx were obtained and subjected to microbiological analysis and biofilm-forming capacity by three methods: tube methods, Congo red staining, and microtiter plate method. The various specific genes were amplified by polymerase chain reaction. The amplified gene products were separated by gel electrophoresis. This was a prospective cohort study conducted on a total of 100 patients with chronic rhinosinusitis and adenotonsillitis. The age of the study participants was between 7 and 53years with a mean age of 29.22 ± 15.03. This study included 54 (54%) nasal tissue samples and 46 (46%) adenotonsillar tissue. The frequently cultured organisms are coagulase-negative staphylococci (17%), E. coli (10%), Citrobacter (10%), and Klebsiella (7%). Staphylococcus aureus (4), and Methicillin-resistant Staphylococcus aureus (3) produced strong biofilm. Acenobacter (3), Citrobacter (4), and E. coli (4) showed moderate biofilm production. Coagulase-negative Staphylococcus aureus (11), E. coli (6), and Klebsiella (7) showed weak biofilm formation. Citrobacter (6), and Coagulase negative Staphylococcus aureus (6) were negative for biofilm production. Staphylococcus aureus expressed mecA gene (3) and Panton-Valentine Leukocidin gene (2), Pseudomonas expressed mucA gene (2), Citrobacter expressed blaCARB-2 (4) qnrA gene (2), E. coli expressed bla SHV (2) and bla TEM1 gene (2) and Klebsiella expressed Kfu (2) and uge (1). Acenobacter was negative for blaIMP1, blaVIM2 genes. This study adds to the information on the common pathogens-forming biofilms in various nasal pathologies and adenotonsillitis. The knowledge that a particular organism has a higher biofilm-forming capacity will help to sensitize the physician that factors such as biofilms may be at play and take appropriate measures.

Prevalence, multiple antibiotic resistance and virulence profile of methicillin-resistant Staphylococcus aureus (MRSA) in retail poultry meat from Edo, Nigeria.

Staphylococcus aureus causes staphylococcal food poisoning and several difficult-to-treat infections. The occurrence and dissemination of methicillin-resistance S. aureus (MRSA) in Nigeria is crucial and well documented in hospitals. However, findings on MRSA from meat in the country are yet to be adequately reported. The current study determined the prevalence, virulence profile and antibiogram characteristics of MRSA from a raw chicken product from retail outlets within Edo. A total of 368 poultry meat samples were assessed for MRSA using a standard culture-based approach and characterized further using a molecular method. The antimicrobial susceptibility profile of the isolates was determined using the disc diffusion method. The biofilm profile of the isolates was assayed via the crystal violet microtitre-plate method. Virulence and antimicrobial resistance genes were screened using polymerase chain reaction via specific primers. Of the samples tested, 110 (29.9%) were positive for MRSA. All the isolates were positive for deoxyribonuclease (DNase), coagulase and beta-hemolysis production. Biofilm profile revealed 27 (24.55%) weak biofilm formers, 18 (16.36%) moderate biofilm formers, and 39 (35.45%) strong biofilm formers. The isolates harboured 2 and ≤17 virulence genes. Enterotoxin gene profiling revealed that 100 (90.9%) isolates harboured one or more genes. Resistance against the tested antibiotics followed the order: tetracycline 64(58.2%), ciprofloxacin 71(64.6%), trimethoprim 71(64.6%) and rifampin 103(93.6%). A total of 89 isolates were multidrug-resistant, while 3 isolates were resistant to all 22 antibiotics tested. The isolates harboured antimicrobial-resistant determinants such as methicillin-resistant gene (mecA), tetracycline resistance genes (tetK, tetL), erythromycin resistance genes (ermA, ermC), trimethoprim resistance gene (dfrK). All the staphylococcal cassette chromosome mec (SCCmec) IVa and SCCmec V positive isolates harboured the Panton-Valentine Leukocidin Gene (PVL). In conclusion, S. aureus was resistant to commonly used antibiotics; a concern to public health concerning the transmission of these pathogens after consuming these highlight the significance of antimicrobial and enterotoxigenic monitoring of S. aureus in food chains.