Panton-Valentine Leukocidin Research Articles

Investigation of Methicillin and Panton-Valentine Leukocidin Genes in Staphylococcus aureus Strains Isolated from Clotted Creams Sold in Afyonkarahisar

This study aimed to investigate the methicillin and Panton-Valentine leukocidin genes in Staphylococcus aureus strains isolated from clotted cream samples produced and sold in Afyonkarahisar. A total of 110 clotted cream samples sold in public bazaars of Afyonkarahisar were collected between November 2019 and December 2020. Conventional cultural methods achieved the isolation of S. aureus from clotted cream samples. For the confirmation of S. aureus strains isolated from samples and determination of mecA and pvl genes in the strains, PCR was used. In this study, while S. aureus was isolated from 14 of 110 clotted cream samples by standard cultural methods, 13 (11.8%) of 110 samples were typed to be S. aureus by PCR. The mecA and pvl genes were found in none of the 13 S. aureus strains. In this study, in which the pvl gene was investigated for the first time in the S. aureus strains isolated from clotted creams in Turkey, it was thought that more research should be done to determine mecA and pvl genes in this traditional product and other dairy products.

Predominance of ST8 and CC1/spa-t1784 methicillin-resistant Staphylococcus aureus isolates in Japan and their genomic characteristics

Methicillin-resistant Staphylococcus aureus (MRSA) has become a serious epidemiologic problem worldwide. In this study, we aimed to investigate recently isolated MRSA types and determine their characteristics. We collected 164 strains isolated from 13 hospitals located in Tokyo and surrounding prefectures. In addition to drug resistance tests, we sequenced whole genomes of the prevalent MRSA clones and analysed their genomic characteristics, such as drug resistance genes, virulence factor genes, and genome arrangements. Multilocus sequencing typing showed that 51% of the SCCmecⅣ MRSA isolates belonged to clonal complex 1 (CC1). Staphylococcus protein A gene (spa) typing showed that 91% of these CC1 isolates could be categorised as t1784 type. These CC1/t1784 isolates possessed genes encoding erythromycin resistance protein, spectinomycin 9-adenylyltransferase, and staphylococcal enterotoxins (SEA, SEI, SEM), but not the pvl gene encoding Panton-Valentine leukocidin. Complete genomic analysis of nine CC1/t1784 isolates showed that they shared an intact phage, which carried no annotated virulence factor genes except for two encoding a hypothetical membrane protein and a teichoic acid biosynthesis protein. No significant genomic rearrangements were observed among the CC1/t1784 isolates. These data and previous reports indicate that this CC1/t1784 clone has been expanding rapidly in Japan without genomic changes.

Necrotizing esophagitis and gastritis due to hypervirulent PVL positive ST 121 CA-MRSA.

Panton-Valentine leucocidin (PVL) positive Staphylococcus aureus usually cause skin/soft tissue infections. Here, we report the first case of a necrotizing esophagitis and gastritis due to a hypervirulent sequence type 121 PVL positive community-associated Methicillin resistant S. aureus, acquired and onset in a Benin’s healthcare facility.

Draft Genome Sequences of 12 Panton-Valentine Leucocidin-Positive and Multidrug-Resistant Methicillin-Resistant Staphylococcus aureus Strains Isolated from an Intensive Care Unit in Pakistan.

ABSTRACTMethicillin-resistant Staphylococcus aureus (MRSA) is a pathogenic bacterium responsible for difficult-to-treat staphylococcal infections due to multidrug resistance. Twelve Panton-Valentine leucocidin (PVL)-positive and multidrug-resistant clinical MRSA isolates from hospitals in Pakistan were sequenced and annotated to investigate genetic markers associated with antimicrobial resistance, virulence, and biofilm formation.

USA300 (sequence type 8) has become a major clone of methicillin-resistant Staphylococcus aureus in northern Taiwan

Most methicillin-resistant Staphylococcus aureus (MRSA) isolates in Taiwan are resistant to clindamycin. MRSA USA300 (sequence type 8), usually susceptible to clindamycin and prevalent in North America, was rarely identified in Taiwan until October 2015. The increasing susceptibility of clinical MRSA isolates to clindamycin prompted the authors to investigate the changing molecular epidemiology of MRSA. Reviewing the antibiograms of clinical MRSA isolates in the study hospital from 2008 to 2018 showed a significant increase in clindamycin susceptibility (CLI-S) from 4.9% (293/5979) in 2008 to 33.2% (1058/3184) in 2018 (Ptrend<0.001). MRSA isolates identified from bloodstream and paediatric samples, preserved systematically in 2008, 2013, 2017 and 2018, were selected for characterization. Molecular analysis revealed that of the 496 CLI-S MRSA isolates, 0%, 6.5%, 44.4% and 48.8% were USA300 [characterized as SCCmec type IV/ Panton-Valentine leukocidin (PVL)-gene-positive/arginine catabolic metabolic element (ACME)-positive] in 2008, 2013, 2017 and 2018, respectively, in paediatric isolates (Ptrend<0.001); and 0%, 7.1%, 47.1% and 50.6% were USA300 (characterized as SCCmec type IV/PVL-gene-positive/ACME-positive) in 2008, 2013, 2017 and 2018, respectively, in bloodstream isolates (Ptrend<0.001). Whole-genome sequencing revealed that 80% of 74 domestic USA300 isolates were clustered into three clades, and all but one isolate belonged to a global clone that diverged in 1994, which further diverged in Taiwan between 2003 and 2006. CLI-S of MRSA increased significantly from 2008 to 2018 in northern Taiwan, mainly due to the increase in USA300. Most USA300 strains circulating in Taiwan have been imported on multiple occasions.

Prevalence and Characterization of PVL-Positive Staphylococcus aureus Isolated from Raw Cow's Milk.

The present study aimed to investigate the prevalence, antibiotic susceptibility profiles, and some toxin genes of Panton-Valentine leukocidin (PVL)-positive Staphylococcus aureus (S. aureus) in unpasteurized raw cow’s milk collected from retail outlets located at Mansoura, Dakahliya governorate, Egypt. In that context, a total of 700 raw cow’s milk samples were investigated for the presence of S. aureus, which was identified in 41.1% (288/700) of the samples. Among the S. aureus isolates, 113 PVL-positive S. aureus were identified and subjected for further analysis. The PVL-positive S. aureus were investigated for the existence of toxin-related genes, including hemolysin (hla), toxic shock syndrome toxin-1 (tst), and enterotoxins (sea, seb, sec, see, seg, sei, and selj). Genotypic resistance of PVL-positive strains was performed for the detection of blaZ and mecA genes. Among the PVL-positive S. aureus, sea, seb, and sec were detected in 44.2, 6.2%, and 0.9%, respectively, while the hla and tst genes were identified in 54.9% and 0.9%, respectively. The blaZ and mecA genes were successfully identified in 84.9 (96/113) and 32.7% (37/113) of the total evaluated S. aureus isolates, respectively. PVL-positive S. aureus displayed a high level of resistance to penicillin, ampicillin, and trimethoprim-sulfamethoxazole. Multidrug resistance (resistant to ≥3 antimicrobial classes) was displayed by all methicillin-resistant S. aureus (MRSA) and 38.2% of methicillin-sensitive S. aureus (MSSA) isolates. The obtained findings are raising the alarm of virulent PVL-positive MRSA clones in retail milk in Egypt, suggesting the requirement for limiting the use of β-lactam drugs in food-producing animals and the importance of implementing strong hygiene procedures in dairy farms and processing plants.

Genomic epidemiology and characterisation of penicillin-sensitive Staphylococcus aureus isolates from invasive bloodstream infections in China: an increasing prevalence and higher diversity in genetic typing be revealed

ABSTRACT Many countries have reported increasing rates of penicillin-susceptible methicillin-sensitive Staphylococcus aureus (MSSA-PENS). To date, there is relatively little known about the current situation and molecular characteristics of MSSA-PENS in China. In this study, we carried out a laboratory-based multi-region retrospective study to investigate the genomic epidemiology and characterisation of MSSA-PENS isolated from invasive bloodstream infections (BSIs) across 17 provinces. The prevalence of MSSA-PENS isolates increased significantly over the 6-year period, with the proportion increasing from 3.51% in 2014–8.80% in 2019, an average relative increase of 22.14% per year (95% confidence interval 9.67%-34.61%, P for trend <0.001), suggesting that China is experiencing a resurgence of MSSA-PENS. Phylogenetic analysis showed a higher strain diversity occurred; the most frequent clonal complexes (CCs) identified were CC188 (17.14%), CC398 (15.71%) and CC5 (15.71%). Over half of MSSA-PENS strains were pan-susceptible, with erythromycin the most frequent resistance observed. Moreover, 25 isolates were identified as immune evasion cluster negative, including CC15, CC188 and CC1, and 6 strains encoded the Panton-Valentine leucocidin gene. Importantly, virulence assays showed that MSSA-PENS exhibited a level of virulence comparable to that of penicillin-resistant MSSA (MSSA-PENR), indicating that more-sensitive strains should not be mistaken for lacking aggressiveness in vivo. Furthermore, 11 of these isolates were confirmed as blaZ positive but phenotype sensitive, with different amino acid changes in blaZ. Our data support the recommendation to clinicians regarding the usage of penicillin in invasive BSIs caused by MSSA-PENS, which might create a novel opportunity for better antimicrobial stewardship in the future.

Sub-Inhibitory Concentrations of Oxacillin, but Not Clindamycin, Linezolid, or Tigecycline, Decrease Staphylococcal Phenol-Soluble Modulin Expression in Community-Acquired Methicillin-Resistant Staphylococcus aureus.

ABSTRACTStaphylococcus aureus (SA) is a major human pathogen producing virulence factors, such as Panton-Valentine-leucocidin (PVL), alpha-hemolysin (Hla), and phenol-soluble-modulins alpha (PSMα), including delta-hemolysin (Hld). Unlike oxacillin, clindamycin and linezolid subinhibitory concentrations (sub-MIC) display an anti-toxin effect on PVL and Hla expression. Few studies have investigated PSMα and Hld expression modulation by antibiotics. Herein, we assessed the effect of antibiotic sub-MIC on PSMα1 and Hld expression for 4 community-acquired methicillin-resistant SA (CA-MRSA), 2 strains belonging to USASA300 and 2 strains belonging to ST80 European clone. SA were grown under oxacillin, clindamycin, linezolid, or tigecycline. After incubation, culture pellets were used for the determination of psmα1, pmtB, pmtR mRNA, and RNAIII levels by relative quantitative RT-PCR. PSMα1 and Hld expressions were measured in supernatant using high-performance-liquid-chromatography coupled to mass-spectrometry (HPLC-MS). Oxacillin sub-MIC reduced PSMα1 and Hld production, partially related to mRNA variations. For other antibiotics, effects on toxin expression were strain or clone dependent. Antibiotic effect on mRNA did not always reflect protein expression modulation. Variations of pmtB, pmtR mRNA, and RNAIII levels were insufficient to explain toxin expression modulation. Altogether, these data indicate that PSMα and Hld expressions are modulated by antibiotics (potential anti-toxin effect of oxacillin) differently compared to PVL and Hla.IMPORTANCE Staphylococcal toxins play an important role in the physiopathology of staphylococcal infections. Subinhibitory concentrations (sub-MIC) of antibiotics modulate in vitro toxins expression in S. aureus: clindamycin (CLI) and linezolid (LIN) display an anti-toxin effect on Panton-Valentine leucocidin and alpha-hemolysin production, while oxacillin (OXA) has an inducing effect. Few studies have focused on the modulation of phenol-soluble modulins alpha (PSMα) including delta-hemolysin expression by sub-MIC antibiotics. The aim of the present study was to investigate the effects of sub-MIC antibiotics on the expression of PSMα toxins for 4 community-acquired methicillin-resistant S. aureus (CA-MRSA) clinical isolates. The data presented herein confirm that OXA sub-MICs constantly inhibit PSMα production for CA-MRSA. Certain strains of S. aureus are highly sensitive to sub-MICs of protein synthesis inhibitory agents, resulting in an important increase of mRNA levels to overcome the intrinsic ribosome blockage ability of these antibiotics, eventually translating in increased expression of toxins.

Comparative Genomic Analysis of the Human Variant of Methicillin-Resistant Staphylococcus aureus CC398 in Japan and Korea.

Staphylococcus aureus clonal complex (CC) 398 is a major clonal type of livestock-associated methicillin-resistant S. aureus and comprise both a human variant and a livestock-associated variant. We have previously identified three sequence type (ST) 1232 strains from Japanese patients (THI2018-120 and N1195) and a Vietnamese patient (S36). In this study, we found an ST1232 strain in a Korean patient (BDH17) and compared the genomes of the ST1232 strains isolated in Korea and Japan. Whole-genome sequencing and a phylogenetic tree based on single nucleotide polymorphisms showed that all ST1232 strains were human variants of S. aureus CC398 and were similar to a common lineage of Southeast Asia. All strains carried ϕSa2, ϕSa3, and Tn554, which included Panton-Valentine leukocidin, immune evasion cluster, and antimicrobial resistance genes, respectively. THI2018-120 and N1195 carried slightly different staphylococcal cassette chromosome mec element from BDH17 due to the insertion of a IS30 family. In addition, the strains originating from Japanese patients possessed a unique genetic element, blaZ-Tn4001-Tn554 element. In this study, we found that the ST1232 strains isolated in Korea and Japan are genetically closely related to each other. However, presence of the unique genetic elements suggests that the strains originating from Japanese patients may have evolved independently in Japan.

Complete genome and plasmid sequences of Staphylococcus aureus strain COL52-A5 isolated from a persistent nasal carrier

Persistent colonization with Staphylococcus aureus is associated with a higher risk of invasive infections. With increasing rates of colonization, especially with antibiotic-resistant strains, it may be useful to identify specific characteristics of colonization that confer a greater infection risk. Therefore, whole-genome sequencing (WGS) of an S. aureus strain isolated from a medical student identified as a persistent carrier in Cartagena, Colombia, was performed to better characterize the strain and to identify genetic components associated with virulence and antimicrobial resistance. Antimicrobial susceptibility testing was performed for several antibiotics. Total genomic DNA was extracted and WGS was performed on a PacBio RS II sequencing platform. Whole-genome assembly was generated using PacBio SMRT Analysis v.2.3.0 and HGAP v.1.2. In silico analysis of the chromosomal and plasmid components of this strain was performed using tools available online. Strain COL52-A5 was identified as a Panton-Valentine leukocidin (PVL)-positive methicillin-resistant S. aureus (MRSA) carrying staphylococcal cassette chromosome mec (SCCmec) type IVa and was resistant to cefoxitin, erythromycin, clindamycin and tetracycline. The completely closed genome of strain COL52-A5 was 2 820 086 bp with a GC content of 32.84% and it harboured one large plasmid, two active prophages, five antimicrobial resistance determinants and several virulence factors. The allelic profile was consistent with sequence type ST923 (CC8). Genome analysis of strain COL52-A5 found numerous virulence and resistance factors. Further comparison of genomic sequences from persistent and intermittent strains is required to gain insights into the genomic features that favour persistent carriage in healthy individuals.

Panton-Valentine Leucocidin-Positive Staphylococcus Aureus Gonarthritis in a Healthy Adult Leads To Fulminant Sepsis with Multiple Metastatic Soft Tissue Infection and Necessity of Extracorporeal Membrane Oxygenation

Background: Infections with Panton-Valentine leucocidin (PVL) positive Staphylococcus aureus ( S. aureus ) are often complicated by necrotizing pneumonia, myositis and osteomyelitis. Case Description: We describe a 50 years old, previously healthy male which presented a severe infection with PVL-positive, methicillin- susceptible S. aureus (MSSA) in his left knee after returning from China. He developed a fulminant sepsis with necrotizing pneumonia, acute respiratory distress syndrome (ARDS), acute renal failure and multiple soft tissue abscesses. Extra-corporeal membrane oxygenation (ECMO) was needed for five days. The patient recovered after multiple surgical interventions and long-term antibiotic treatment and eventually returned to work five months after initial admission. Conclusion: While most staphylococcal skin and soft tissue infections (SSTI) show a favorable outcome, SSTI caused by PVL- positive bacteria can lead to fulminant and fatal disease manifestations. Immunocompetent individuals are equally affected as immunocompromised ones. Early suspicion, surgical intervention with debridement and drainage of abscess formations are of key importance in concert with appropriate antibiotic therapy without delay. Imaging should be done to identify clinically silent foci.

Molecular characterisation of virulence genes in Staphylococcus aureus associated with clinical bovine mastitis

Staphylococcus aureus is the most frequently isolated pathogen from bovine mastitis including subclinical, clinical, and chronic infections. Virulence factors possessed by S. aureus aid in causing infection and inflammation by producing toxins and proteins, which are responsible for the pathogenesis of the disease. In the current study out of 51 animals presented with clinical mastitis, S. aureus was isolated from the milk of 18 animals. S. aureus was confirmed by genus and species level identification using polymerase chain reaction. Molecular characterization of selected virulence genes including thermonuclease (nuc) and Panton Valentine Leucocidin (PVL) was performed in all the S. aureus isolates. Presence of nuc gene was observed in all the isolates (100 %) of S. aureus. No isolates were found to be positive for the presence of PVL gene. Profiling the virulence genes is an important tool for epidemiological studies of mastitis, which can be employed for the prevention and control of the disease.

The survival of epidemic and sporadic MRSA on human skin mimics is determined by both host and bacterial factors.

Bacterial survival on, and interactions with, human skin may explain the epidemiological success of MRSA strains. We evaluated the bacterial counts for 27 epidemic and 31 sporadic MRSA strains on 3D epidermal models based on N/TERT cells (NEMs) after 1, 2 and 8 days. In addition, the expression of antimicrobial peptides (hBD-2, RNase 7), inflammatory cytokines (IL-1β, IL-6) and chemokine IL-8 by NEMs was assessed using immunoassays and the expression of 43 S. aureus virulence factors was determined by a multiplex competitive Luminex assay. To explore donor variation, bacterial counts for five epidemic and seven sporadic MRSA strains were determined on 3D primary keratinocyte models (LEMs) from three human donors. Bacterial survival was comparable on NEMs between the two groups, but on LEMs, sporadic strains showed significantly lower survival numbers compared to epidemic strains. Both groups triggered the expression of immune factors. Upon interaction with NEMs, only the epidemic MRSA strains expressed pore-forming toxins, including alpha-hemolysin (Hla), gamma-hemolysin (HlgB), Panton-Valentine leucocidin (LukS) and LukED. Together, these data indicate that the outcome of the interaction between MRSA and human skin mimics, depends on the unique combination of bacterial strain and host factors.

Paediatric osteoarticular infections caused by staphylococcus aureus producing panton-valentine leucocidin in morocco: Risk factors and clinical features.

Objective:We aimed to estimate the prevalence of Staphylococcus aureus producing Panton–Valentine leucocidin (PVL) isolated from children diagnosed with osteoarticular infections (OAIs), and to examine risk factors and clinical features.Methods:This prospective study was conducted from January 2017 to December 2018. All hospitalised children diagnosed with S. aureus OAI are included. Blood cultures, articular fluids, synovial tissues and/or bone fragments were collected for bacteriological culture. Antimicrobial susceptibility tests were determined by disk diffusion method. Genes encoding methicillin resistance (mecA) and PVL virulence factors (luk-S-PV and luk-F-PV) were detected by multiplex polymerase chain reaction. The demographic, clinical, laboratory, radiographic and clinical features were reviewed prospectively from medical records.Results:A total of 37 children with S. aureus OAIs were included, 46% of them have PVL-positive infection and 70.6% were male. The mean age was 8.12 years (±4.57), and almost were from rural settings (76.5%). Children with Staphylococcus aureus producing Panton–Valentine leucocidin (SA-PVL) were significantly associated with type of infection (P = 0.005), location of infection (P = 0.037) and abnormal X-ray (P = 0.029). All strains SA-PVL+ are sensitive to methicillin, but one strain SA-PVL negative was methicillin-resistant S. aureus, confirmed by gene mecA positive.Conclusion:The prevalence of S. aureus infections producing PVL toxin was high in OAIs amongst Moroccan children, mainly due to methicillin-susceptible S. aureus. Type and location of infections and abnormal X-ray were significantly associated with SA-PVL. Routine diagnostic testing of PVL-SA, continuous epidemiological surveillance and multidisciplinary management of OAI is essential to prevent serious complications.

Description of Methicillin-Susceptible Staphylococcus aureus Clonal Complex 30 Related to the Pandemic Phage Type 80/81 Isolated from Patients in Three Tertiary Hospitals in Jos, North Central Nigeria

Objective: The prevalence of phage 80/81 Staphylococcus aureus strains, the pandemic strains that were dominant in the 1950s, had declined in the 1960s and 1970s. However, these strains have reemerged in some countries in recent years. This study investigated the antibacterial resistance, virulence, and the genetic backgrounds of CC30-MSSA isolates obtained from patients in three tertiary hospitals. Materials and Methods: Twenty-two CC30-MSSA isolates cultured from different clinical samples were investigated using antibiotic sensitivity testing, spa typing, multilocus sequence typing, and DNA microarray analysis. Results: All 22 isolates were susceptible to vancomycin (MIC ≤2 μg/mL), teicoplanin (MIC ≤2 μg/mL), and cefoxitin but were resistant to penicillin G (n = 22; 100.0%), tetracycline (n = 12; 54.5%), ciprofloxacin (n = 15; 68.2%), cadmium acetate (n = 22; 100%), mercuric chloride (n = 13; 59.1%), and ethidium bromide (n = 3; 13.6%). The isolates belonged to sequence type, ST30, and five spa types: t012 (n = 12; 54.5%), t019 (n = 5; 22.7%), t017 (n = 2; 9.1%), t037 (n = 2; 9.1%), and t318 (n = 1; 4.5%). All 22 isolates were positive for agrIII, cap8, clfA, clfB, icaA, icaC, icaD, cna, and staphylococcal enterotoxin gene clusters (seg, sei, sem, sen, seo, seu). Eight isolates carried lukS-PV and lukF-PV that code for Panton-Valentine leukocidin. Conclusion: The current CC30-MSSA isolates share phenotypic and genotypic characteristics with the pandemic phage 80/81 isolates that were common in the 1950s and 1960s. Continued surveillance is recommended to keep abreast of the changing epidemiology of S. aureus causing healthcare and community-associated infections.

Isolation and characterization of Staphylococcus argenteus strains from retail foods and slaughterhouses in Japan

Staphylococcus argenteus has been recently established as a novel species of Staphylococcus aureus complex. It is known to cause various human diseases, such as skin and soft-tissue infections, sepsis, and staphylococcal food poisoning, although the source of infection has not been clearly described. In food poisoning cases, the source of bacterial contamination in food is unknown. This study examined the prevalence of S. argenteus among retail fresh food and poultry slaughterhouses in Japan. Among 642 food samples examined, successful isolation of S. argenteus was achieved in 21 of 151 (13.9%) chicken samples. No isolations from pork, beef, fish, or vegetables in retail markets were confirmed. Multiple-locus sequence typing revealed that the 21 isolates were classified into four sequence types (ST) that were divided into 14 subtypes using spa-typing. All food isolates were susceptible to methicillin and did not show positivity for the Panton-Valentine leukocidin gene. When bacteria were isolated from two poultry slaughterhouses in the same region, 14 S. argenteus strains were successfully isolated from only one slaughterhouse. Thirteen of 14 strains were isolated from a poultry carcass and slaughterhouse environments during a certain sampling period and were all classified as ST5961 with identical spa-type. Also, the number of single nucleotide variants (SNVs) detected on the core genomes of the same 13 strains were between 0 and 17, suggesting a long-term inhabitation of an S. argenteus strain inside the facility. Furthermore, one isolate from chicken meat was also genetically linked with the same lineage of slaughterhouse isolates, with ≤15 SNVs being detected. Additionally, one slaughterhouse isolate from chiller water and three chicken isolates were classified into the same cluster by phylogenetic analysis, although the number of pairwise SNVs ranged from 62 to 128. To the best of the authors' knowledge, this is the first study that demonstrated S. argenteus in a food processing facility and the possible bacterial contamination on food during food processing.

Staphylococcus aureus isolates from Eurasian Beavers (Castor fiber) carry a novel phage-borne bicomponent leukocidin related to the Panton-Valentine leukocidin

Staphylococcus aureus can be a harmless coloniser, but it can also cause severe infections in humans, livestock and wildlife. Regarding the latter, only few studies have been performed and knowledge on virulence factors is insufficient. The aim of the present study was to study S. aureus isolates from deceased wild beavers (Castor fiber). Seventeen isolates from eleven beavers, found in Germany and Austria, were investigated. Antimicrobial and biocide susceptibility tests were performed. Isolates were characterised using S. aureus-specific DNA microarrays, spa typing and whole-genome sequencing. From two isolates, prophages were induced by mitomycin C and studied by transmission electron microscopy. Four isolates belonged to clonal complex (CC) 8, CC12, and CC398. Twelve isolates belonged to CC1956 and one isolate was CC49. The CC49 and CC1956 isolates carried distinct lukF/S genes related to the Panton-Valentine leukocidin (PVL) from human isolates of S. aureus. These genes were located on related, but not identical, Siphovirus prophages. The beavers, from which those isolates originated, suffered from abscesses, purulent organ lesions and necrotising pneumonia, i.e., clinical manifestations resembling symptoms of severe PVL-associated disease in humans. It might thus be assumed that the “Beaver Leukocidin (BVL, lukF/S-BV)”-positive strains are beaver-specific pathogens, and further studies on their clinical role as well as on a possible transmissibility to other species, including humans, are warranted.

Clinical Features and Molecular Characteristics of Methicillin-Susceptible Staphylococcus aureus Ocular Infection in Taiwan.

This study analyzed the clinical features and molecular characteristics of methicillin-susceptible Staphylococcus aureus (MSSA) ocular infections in Taiwan and compared them between community-associated (CA) and health-care-associated (HA) infections. We collected S. aureus ocular isolates from patients at Chang Gung Memorial Hospital between 2010 and 2017. The infections were classified as CA or HA using epidemiological criteria, and the isolates were molecularly characterized using pulsed-field gel electrophoresis, multilocus sequence typing, and Panton-Valentine leukocidin (PVL) gene detection. Antibiotic susceptibility was evaluated using disk diffusion and an E test. A total of 104 MSSA ocular isolates were identified; 46 (44.2%) were CA-MSSA and 58 (55.8%) were HA-MSSA. Compared with HA-MSSA strains, CA-MSSA strains caused a significantly higher rate of keratitis, but a lower rate of conjunctivitis. We identified 14 pulsotypes. ST 7/pulsotype BA was frequently identified in both CA-MSSA (28.3%) and HA-MSSA (37.9%) cases. PVL genes were identified in seven isolates (6.7%). Both CA-MSSA and HA-MSSA isolates were highly susceptible to vancomycin, teicoplanin, tigecycline, sulfamethoxazole–trimethoprim, and fluoroquinolones. The most common ocular manifestations were keratitis and conjunctivitis for CA-MSSA and HA-MSSA, respectively. The MSSA ocular isolates had diverse molecular characteristics; no specific genotype differentiated CA-MSSA from HA-MSSA. Both strains exhibited similar antibiotic susceptibility.

Prevalence of Methicillin-Resistant Staphylococcus Species Among Filarial Lymphedema Patients in Ahanta West District of Ghana

BackgroundFilarial pathologies such as lymphedema may be associated with complications such as chronic non-healing wounds. Nonetheless, the role of bacterial population colonizing the lymphedematous legs has been posited to worsen the conditions of those living with the infection. These bacteria are usually composed of staphylococcal species partly because they are commensals. Thus, this present study sought to type the methicillin-resistant Staphylococcus aureus (MRSA) prevalence among individuals presenting with filarial lymphedema, particularly as MRSA tends to affect treatments options.MethodsWe recruited individuals (n = 321) with stages I–VII of lymphedema in a cross-sectional study in the Ahanta West district of the Western Region of Ghana. Swabs from lymphedematous limb ulcers, pus, and cutaneous surfaces were cultured using standard culture-based techniques. The culture isolates were later identified using Matrix-assisted Laser Desorption/Ionization Time of Flight (MALDI-TOF) mass spectrometry.ResultsA total of 192 Staphylococci species were isolated, with an overall prevalence of 39.7% (95% CI: 35%–44%; N = 483). S. hominis was the most prevalent species (23.95%), followed by S. haemolyticus (20.83%), S. epidermidis (15.10%), S. aureus (10.41%), and S. saprophyticus (9.32%). The remaining 20.34% were distributed among S. wanneri, S. sciuri, S. pasteuri, S. xylosus, S. simulans, S. cohnii, S. caprae, S. lugdunensis, and S. capitis. MRSA, containing mecA gene, was detected in 21 out of 31 Staphylococci isolates tested, with an overall prevalence of 68% (95% CI: 51%–84%). In addition, a virulent gene, Panton–Valentine leukocidin (PVL), which is usually associated with S. aureus, was detected in 20/31 (64.5%) S. aureus in the study.ConclusionThese results suggest that MRSA species may pose a challenge to the treatment of filarial lymphedema with antibiotics particularly, as doxycycline is currently being piloted in some endemic areas to treat the infection. Thus, intensive antimicrobial resistance surveillance should be conducted in endemic areas by health authorities to forestall the dilemma of multidrug resistance not only against lymphatic filariasis (LF) infection but other diseases.

Emergence of Methicillin-Resistant Staphylococcus aureus ST239/241 SCCmec-III Mercury in Eastern Algeria.

In this paper, we investigate the epidemiology of infections-associated Staphylococcus aureus (S. aureus) from the Medical Intensive Care Unit (MICU) at University Hospital Center of Constantine (UHCC) in Algeria, with a special emphasis on methicillin-resistant strains (MRSA) revealed by cefoxitin disks (30 μg), then confirmed by penicillin-binding protein (PBP2a) agglutination and real-time polymerase chain reaction (RT-PCR) targeting mecA and mecC genes. Staphylococcal Cassette Chromosome mec (SCCmec type), staphylococcal protein A (spa-type), multilocus sequence type (MLST), Panton–Valentine Leucocidin (PVL), and toxic shock syndrome toxin-1 (TSST-1) were further investigated in all isolates, and whole genome sequencing was performed for a selected subset of three hospital-acquired MRSA (HA-MRSA) isolates. A measurement of 80% out of the 50 S. aureus isolates were identified as HA-MRSA harbouring the mecA gene, and 72.5% of them were multidrug resistant (MDR). Twelve STs, four different SCCmec cassettes, fourteen spa types, ten isolates Panton–Valentine Leukocidin (PVL)-positive, and three isolates TSST-1 were identified. Interestingly, there was a high prevalence (n = 29; 72.5%) of a worrisome emerging clone: the HA-MRSA ST239/241 SCCmec-III mercury with PVL negative, resistant to β-lactams, aminoglycosides, quinolones, and tetracyclines. Other clones of HA-MRSA isolates were also identified, including PVL-positive ST80 SCCmec-IV/SCCmec-unknown (22.5%), ST34 SCCmec-V with TSST-1 positive (2.5%), and PVL-negative ST72 SCCmec-II (2.5%). Genome analysis enables us to describe the first detection of both PVL-negative HA-MRSA ST239/241 SCCmec-III mercury carrying ccrC, as well as SCCmec-V cassette, which dramatically changes the epidemiology of S. aureus infections in one of the hospitals in eastern Algeria.