Community-Acquired Staphylococcus argenteus Sequence Type 2250 Bone and Joint Infection, France, 2017

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 of Staphylococcus argenteus among food handlers, kitchen utensils, and food samples in Japan

Staphylococcus argenteus has received increased attention from an aspect of food safety since several food poisoning outbreaks caused by the bacterium were reported in Japan. However, S. argenteus prevalence among food handlers and utensils has not yet been investigated. In this study, we investigated S. argenteus prevalence among a collection of coagulase-positive staphylococci (CPS) that were isolated during food sanitary inspections in Japan. Out of a total of 191 CPS isolates, 14 were identified as S. argenteus. One was isolated from shelled shrimp, nine were isolated from food handlers' hand swabs, and four were isolated from kitchen utensils. Whole-genome sequencing revealed that transmission of S. argenteus from human hands to utensils was possible. Though all 14 isolates were negative for the pvl and tst-1 genes, 6 harbored the seb gene. Only 21.4% of S. argenteus isolates were resistant to antibiotics, while 62.1% of the S. aureus isolates from the same sources were confirmed to be resistant. To the best of our knowledge, this is the first report to demonstrate possible transmission of S. argenteus from food handlers to utensils in food-processing environments.

Prevalence and characterization of Staphylococcus aureus and Staphylococcus argenteus isolated from rice and flour products in Guangdong, China

Staphylococcus aureus and Staphylococcus argenteus have been implicated in food poisoning outbreaks, and have been found in various types of food products according to our previous study. Rice and flour products are popular and widely consumed around the world. However, limited data are available on the microbial safety of S. aureus in rice and flour products, and S. argenteus has never been reported. Thus, this study aimed to investigate the contamination of S. aureus and S. argenteus in 250 fresh rice and flour product samples from five cities in Guangdong, China. According to qualitative and quantitative analyses, 68 (27.2 %) and 11 (4.4 %) samples were positive for S. aureus and S. argenteus, including 9 samples that exceeded 100 MPN/g. For antibiotics susceptibility tests in 16 antibiotics, the S. aureus isolates exhibited higher rates of resistance and multidrug resistance than S. argenteus. The S. aureus and S. argenteus isolates were mainly resistant to penicillin (70.21 %; 79.17 %), tetracycline (20.21 %; 58.33 %) and azithromycin (19.68 %, 8.33 %). However, the other antibiotic resistance rates were <10 %. Furthermore, the genetic background of the isolates was analyzed by whole-genome sequencing (WGS). As a result, the S. aureus isolates were divided into 18 known sequence types (STs) and 4 novel STs (ST7675, ST7679, ST7680 and ST7682), which mainly belonged to ST188 (20.6 %) and ST6 (14.7 %). The S. argenteus isolates mainly belonged to ST2250 (90.9 %), with a novel type (ST7683). In total, 36 and 16 antibiotic resistance genes (ARGs) were found in S. aureus and S. argenteus isolates, respectively. In addition, 91 virulence genes (VFs) were detected in S. aureus isolates as well as 90 % of core VFs were similar to S. argenteus. More than 20 % of the S. aureus isolates carried the classic enterotoxin gene (sea-sec), but chp, cna and map were free in all S. argenteus isolates. Importantly, 33.8 % of S. aureus isolates belonged to the immune evasion cluster (IEC) type B, whereas most of S. argenteus isolates (90.9 %) belong to IEC type E. According to the phylogenetic analysis, the S. aureus and S. argenteus isolates in fresh rice and flour products may indicate loss or acquisition of ARGs and VFs to survive and adapt to the environment. Our study confirmed the presence of S. argenteus in rice and flour products at first and focused on the multi-dimensional systematic comparative analysis of S. aureus and S. argenteus to reveal their ubiquity and similarities or differences, and provide more accurate and effective basic information for follow-up monitoring and tracking.

Prevalence and Characteristics of Invasive Staphylococcus argenteus among Patients with Bacteremia in Hong Kong

Staphylococcus argenteus is a novel Staphylococcus species derived from Staphylococcus aureus. Information on the prevalence and genetic characteristics of invasive S. argenteus in Asia is limited. In this study, 275 invasive S. aureus complex strains were retrieved from blood culture specimens in Hong Kong and re-analyzed using MALDI-TOF mass spectrometry and an in-house multiplex real-time PCR for S. argenteus. The prevalence of invasive S. argenteus in Hong Kong was found to be 4.0% (11/275). These strains were primarily susceptible to commonly used antibiotics, except penicillin. Whole-genome sequencing revealed the circulation of three S. argenteus genotypes (ST-2250, ST-1223, and ST-2854) in Hong Kong, with ST-2250 and ST-1223 being the predominant genotypes. The local ST-2250 and ST-1223 strains showed close phylogenetic relationships with isolates from mainland China. Antimicrobial-resistant genes (fosB, tet-38, mepA, blaI, blaZ) could be found in nearly all local S. argenteus strains. The ST-1223 and ST-2250 genotypes carried multiple staphylococcal enterotoxin genes that could cause food poisoning and toxic shock syndrome. The CRISPR/Cas locus was observed only in the ST-2250 strains. This study provides the first report on the molecular epidemiology of invasive S. argenteus in Hong Kong, and further analysis is needed to understand its transmission reservoir.

Genetic Characteristics of Methicillin-Resistant Staphylococcus argenteus Isolates Collected in the Dutch National MRSA Surveillance from 2008 to 2021

Staphylococcus argenteus is a recently described member of the Staphylococcus aureus complex (SAC) and is associated with human disease. The frequency and intensity of infections caused by S. argenteus are similar to those of Staphylococcus aureus. S. argenteus can harbor antibiotic resistance genes and a variety of virulence factors analogous to methicillin-resistant S. aureus (MRSA). The aim of our study was to analyze a collection of isolates in the Dutch national MRSA surveillance from January 2008 until March 2021 that were nontypeable by multilocus variable-number tandem-repeat analysis (MLVA). Matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-ToF MS) was used for identifying the S. argenteus isolates, and whole-genome sequencing and SeqSphere were used to generate an in-house whole-genome multilocus sequence typing (wgMLST) scheme for typing the isolates. Furthermore, the presence of antibiotic resistance genes, replicons, and virulence genes was determined. Of 52,467 isolates submitted as MRSA from January 2008 until March 2021, 64 isolates (0.12%) were nontypeable with MLVA, and 54 of them were identified with mass spectrometry (MALDI-ToF MS) as S. argenteus. It appeared in retrospect that the first methicillin-resistant S. argenteus (MRSArg) was already submitted in 2008. An in-house-developed S. argenteus wgMLST scheme revealed that S. argenteus isolates clustered in 5 genomic groups which were characterized by distinct MLST types, resistomes, plasmid replicon families, and virulence factors. All but one isolate carried the staphylococcal chromosomal cassette mec (SCCmec) type IV harboring the methicillin resistance gene mecA and represent MRSArg. Most of the isolates with SCCmec subtype IVc(2B) had a trimethoprim resistance gene, dfrG, and harbored a blaZ-carrying plasmid, and most MRSArg isolates have the immune-modulating genes scn and sak. Nine of the 47 isolates carried enterotoxin-encoding genes seg, sei, sem, seo, and seu, which might be able to cause food poisoning. In some persons there was long-term persistence of MRSArg, and there were several genetically related MRSArg isolates in people living in close proximity, suggesting direct human-human transmission. IMPORTANCE We show that MRSArg has been circulating in the Netherlands since at least 2008. Although MRSArg is distinct from MRSA, it has a comparable population structure and carries similar resistance and virulence genes. The Dutch national MRSA surveillance has been expanded to include other methicillin-resistant members of the S. aureus complex, such as S. argenteus and Staphylococcus schweitzeri.

Description of Staphylococcal Strains from Straw-Coloured Fruit Bat (Eidolon helvum) and Diamond Firetail (Stagonopleura guttata) and a Review of their Phylogenetic Relationships to Other Staphylococci

The phylogenetic tree of the Staphylococcus aureus complex consists of several distinct clades and the majority of human and veterinary S. aureus isolates form one large clade. In addition, two divergent clades have recently been described as separate species. One was named Staphylococcus argenteus, due to the lack of the “golden” pigment staphyloxanthin. The second one is S. schweitzeri, found in humans and animals from Central and West Africa. In late 2021, two additional species, S. roterodami and S. singaporensis, have been described from clinical samples from Southeast Asia. In the present study, isolates and their genome sequences from wild Straw-coloured fruit bats (Eidolon helvum) and a Diamond firetail (Stagonopleura guttata, an estrildid finch) kept in a German aviary are described. The isolates possessed staphyloxanthin genes and were closer related to S. argenteus and S. schweitzeri than to S. aureus. Phylogenetic analysis revealed that they were nearly identical to both, S. roterodami and S. singaporensis. We propose considering the study isolates, the recently described S. roterodami and S. singaporensis as well as some Chinese strains with MLST profiles stored in the PubMLST database as different clonal complexes within one new species. According to the principle of priority we propose it should be named S. roterodami. This species is more widespread than previously believed, being observed in West Africa, Southeast Asia and Southern China. It has a zoonotic connection to bats and has been shown to be capable of causing skin and soft tissue infections in humans. It is positive for staphyloxanthin, and it could be mis-identified as S. aureus (or S. argenteus) using routine procedures. However, it can be identified based on distinct MLST alleles, and “S. aureus” sequence types ST2470, ST3135, ST3952, ST3960, ST3961, ST3963, ST3965, ST3980, ST4014, ST4075, ST4076, ST4185, ST4326, ST4569, ST6105, ST6106, ST6107, ST6108, ST6109, ST6999 and ST7342 belong to this species.

Staphylococcus schweitzeri—An Emerging One Health Pathogen?

The Staphylococcus aureus-related complex is formed by the Staphylococcus aureus, Staphylococcus schweitzeri, Staphylococcus argenteus, Staphylococcus roterodami and Staphylococcus singaporensis. Within this complex, S. schweitzeri is the only species mainly found in African wildlife, but it is rarely detected as a colonizer in humans or as a contaminant of fomites. The few detections in humans are most likely spillover events after contact with wildlife. However, since S. schweitzeri can be misidentified as S. aureus using culture-based routine techniques, it is likely that S. schweitzeri is under-reported in humans. The low number of isolates in humans, though, is consistent with the fact that the pathogen has typical animal adaptation characteristics (e.g., growth kinetics, lack of immune evasion cluster and antimicrobial resistance); however, evidence from selected in vitro assays (e.g., host cell invasion, cell activation, cytotoxicity) indicate that S. schweitzeri might be as virulent as S. aureus. In this case, contact with animals colonized with S. schweitzeri could constitute a risk for zoonotic infections. With respect to antimicrobial resistance, all described isolates were found to be susceptible to all antibiotics tested, and so far no data on the development of spontaneous resistance or the acquisition of resistance genes such the mecA/mecC cassette are available. In summary, general knowledge about this pathogen, specifically on the potential threat it may incur to human and animal health, is still very poor. In this review article, we compile the present state of scientific research, and identify the knowledge gaps that need to be filled in order to reliably assess S. schweitzeri as an organism with global One Health implications.

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.

Genomic Analysis of Global Staphylococcus argenteus Strains Reveals Distinct Lineages With Differing Virulence and Antibiotic Resistance Gene Content

Infections due to Staphylococcus argenteus have been increasingly reported worldwide and the microbe cannot be distinguished from Staphylococcus aureus by standard methods. Its complement of virulence determinants and antibiotic resistance genes remain unclear, and how far these are distinct from those produced by S. aureus remains undetermined. In order to address these uncertainties, we have collected 132 publicly available sequences from fourteen different countries, including the United Kingdom, between 2005 and 2018 to study the global genetic structure of the population. We have compared the genomes for antibiotic resistance genes, virulence determinants and mobile genetic elements such as phages, pathogenicity islands and presence of plasmid groups between different clades. 20% (n = 26) isolates were methicillin resistant harboring a mecA gene and 88% were penicillin resistant, harboring the blaZ gene. ST2250 was identified as the most frequent strain, but ST1223, which was the second largest group, contained a marginally larger number of virulence genes compared to the other STs. Novel S. argenteus pathogenicity islands were identified in our isolates harboring tsst-1, seb, sec3, ear, selk, selq toxin genes, as well as chromosomal clusters of enterotoxin and superantigen-like genes. Strain-specific type I modification systems were widespread which would limit interstrain transfer of genetic material. In addition, ST2250 possessed a CRISPR/Cas system, lacking in most other STs. S. argenteus possesses important genetic differences from S. aureus, as well as between different STs, with the potential to produce distinct clinical manifestations.

Staphylococcus argenteus transmission among healthy Royal Marines: A molecular epidemiology case-study

Objectives During a prospective study of S. aureus carriage in Royal Marines recruits, six S. argenteus strains were identified in four recruits. As S. argenteus sepsis leads to mortality similar to S. aureus, we determined the potential for within same troop transmission, to evaluate future outbreak risk. Methods We used whole-genome sequencing to characterise S. argenteus and investigate phylogenetic relationships between isolates. Results S. argenteus strains (t5078, ST2250) were detected in 4/40 recruits in the same troop (training cohort) in weeks 1, 6 or 15 of training. No mec, tsst or LukPV genes were detected. We identified differences of 1-17 core SNPs between S. argenteus from different recruits. In two recruits, two S. argenteus strains were isolated; these could be distinguished by 2 and 15 core SNPs. Conclusions The identification of S. argenteus within a single troop from the total recruit population suggests a common source for transmission, though high number of SNPs were identified, both within-host and within-cluster. The high number of SNPs between some isolates may indicate a common source of diverse isolates or a high level of S. argenteus mutation in carriage. S. argenteus is newly recognized species; and understanding of the frequency of genetic changes during transmission and transition from asymptomatic carriage to disease is required.

Phenotypic and Genomic Profiling of Staphylococcus argenteus in Canada and the United States and Recommendations for Clinical Result Reporting

Staphylococcus argenteus is a newly described species, formerly known as S. aureus clonal complex 75 (CC75). Here, we describe the largest collection of S. argenteus isolates in North America, highlighting identification challenges. We present phenotypic and genomic characteristics and provide recommendations for clinical reporting. Between 2017 and 2019, 22 isolates of S. argenteus were received at 2 large reference laboratories for identification. Identification with routine methods (biochemical, matrix-assisted laser desorption ionization-time of flight mass spectrometry [MALDI-TOF MS], 16S rRNA gene analysis) proved challenging to confidently distinguish these isolates from S. aureus Whole-genome sequencing analysis was employed to confirm identifications. Using several different sequence-based analyses, all clinical isolates under investigation were confirmed to be S. argenteus with clear differentiation from S. aureus Seven of 22 isolates were recovered from sterile sites, 11 from nonsterile sites, and 4 from surveillance screens. While sequence types ST1223/coa type XV, ST2198/coa type XIV, and ST2793/coa type XId were identified among the Canadian isolates, the majority of isolates (73%) belonged to multilocus sequence types (MLST) ST2250/coa type XId and exhibited a high degree of homology at the genomic level. Despite this similarity, 5 spa types were identified among ST2250 isolates, demonstrating some diversity between strains. Several isolates carried mecA, as well as other resistance and virulence determinants (e.g., PVL, TSST-1) commonly associated with S. aureus Based on our findings, the growing body of literature on S. argenteus, the potential severity of infections, and possible confusion associated with reporting, including use of incorrect breakpoints for susceptibility results, we make recommendations for clinical laboratories regarding this organism.

Investigation of a Staphylococcus argenteus Strain Involved in a Chronic Prosthetic-Joint Infection

Staphylococcus argenteus is an emerging species responsible for infections comparable to those induced by Staphylococcus aureus. It has been involved in few chronic or persistent infections so far. In this study, we described a case of a persistent prosthetic-joint infection (PJI) affecting a young woman. We investigated in vitro the virulence traits of the incriminated S. argenteus strain (bone cell invasion, biofilm formation and induction of inflammation) and analyzed its genome, in comparison with two other strains of S. argenteus and two S. aureus isolates. It appeared that this S. argenteus PJI strain combined biofilm formation, osteoblast invasion and intracellular persistence abilities together with genes potentially involved in the escape of the host immune defenses, which might explain the chronicization of the infection.

Thoracic aortic mycotic aneurysm due to Staphylococcus argenteus: A case report

Staphylococcus argenteus was subdivided as a novel species from Staphylococcus aureus in 2014. We herein report a case of mycotic aneurysm caused by S. argenteus. A 59-year-old woman with diabetes and schizophrenia visited at the emergency room because of falling. Chest computed tomography revealed a left humerus fracture and a thoracic aortic aneurysm. With her elevated WBC count and CRP level, she was suspected to have a mycotic aneurysm. After being transferred to our hospital, vascular graft replacement surgery was performed. Isolates of blood cultures and surgical specimens were identified as S. argenteus by Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MAS MALDI Biotyper Ver. 8.0). Although S. argenteus lacks staphyloxanthin, a carotenoid pigment, it is coagulase positive. In addition to traditional and automated biochemical identification systems, even MALDI-TOF MAS may misidentify the organism as S. aureus depending on its version. S. argenteus should be considered when coagulase-negative Staphylococcus like colonies are obtained from samples of S. aureus infection. To our knowledge, this is the first case of aortic mycotic aneurysm caused by S. argenteus in Japan. Although S. argenteus is considered less virulent than Staphylococcus aureus, we should closely monitor the prevalence and the clinical impact of this pathogen on community-acquired infections and health care-associated infections.

Staphylococcus argenteus as an etiological agent of prosthetic hip joint infection: a case presentation

This report presents a case of prosthetic hip infection caused by Staphylococcus argenteus, a potentially overlooked etiology of prosthetic joint infections (PJIs). Whole-genome sequencing showed that the S. argenteus isolate was an ST2250 and clustered within other CC2250 isolates, the largest clonal group of S. argenteus. This sequence type is prevalent and may be associated with invasive infections. The present isolate was phenotypically fully susceptible to all tested antimicrobial agents and genome analysis did not detect any resistance genes, nor were any staphylococcal cassette chromosome residues detected. Despite initial appropriate management with debridement and biofilm-active antibiotics, the outcome was unfavorable with recurrence and a persistent infection treated with suppressive antibiotics. Regarding the repertoire of genomic traits for virulence in S. argenteus, PJIs caused by this bacterium should be treated accordingly as Staphylococcus aureus PJIs.

Staphylococcus argenteus and Staphylococcus schweitzeri are cytotoxic to human cells in vitro due to high expression of alpha-hemolysin Hla

Staphylococcus argenteus and Staphylococcus schweitzeri are newly identified species of the S. aureus-related complex. S. argenteus, as occurring globally and showing significant prevalence and comparable infection and morbidity rates compared to S. aureus, is becoming clinically important. Whole genome sequencing has revealed the presence of several virulence genes but the molecular mechanisms of S. argenteus infection and virulence are largely unknown. Here, we studied the effect of a previously characterized clinical S. argenteus isolate on human cells in vitro. The clinical isolate, together with the S. argenteus type strain MSHR1132T and the S. schweitzeri type strain FSA084T, had a cytotoxic effect on the cells, which showed necrotic cell death after a few hours of treatment. The protein causing the cytotoxic effect was purified and identified by mass spectrometry as alpha-hemolysin, Hla, which is awell-known pore-forming toxin in S.aureus. The cytotoxic effect could be blocked with an antibody against Hla. S.argenteus showed 12–15 fold higher expression levels of hla at the RNA level and 4–6 fold higher expression levels at the protein level compared to S.aureus. The higher expression levels of hla were supported by higher RNA levels of the regulatory factors sarA and saeR. Also, the RNAIII component of the accessory gene regulator (agr) quorum sensing system was 8,000–10,000 fold higher in the S.argenteus isolates compared to S.aureus. This is the first study on the effect of S.argenteus on ahuman cell line and strengthens the idea of significant virulence of S.argenteus.

Molecular Characterization of Staphylococcus aureus Isolates Associated with Nasal Colonization and Environmental Contamination in Academic Dental Clinics

Aim: To determine the genetic makeup of methicillin-sensitive/methicillin-resistant Staphylococcus aureus (MSSA/MRSA) from nasal colonization and environmental contamination in dental clinics. Materials and Methods: Nasal swabs from students and health care workers and environmental swabs were obtained at two academic dental clinics in the United Arab Emirates. The StaphyType DNA microarray-based assay was used for molecular characterization. Results: Forty-eight S. aureus isolates were identified phenotypically (nasal: n = 43; environmental: n = 5), but 6 of these were assigned to S. argenteus by genotyping. These were CC_(argenteus)2596, CC_(arg)2250-MSSA, CC_(arg)2250-MSSA-(Panton Valentine leukocidin [PVL]+) (n = 2), and CC_(arg)2198-MSSA (n = 2). MRSA nasal colonization rate was 5.4% (n/N = 8/146) with the following strain affiliations: CC5-MRSA-[IV+fus+ccrAB], "Maltese Clone"; CC6-MRSA-IV, "WA MRSA-51"; CC22-MRSA-IV (PVL+/tst+); CC22-MRSA-[IV+fus+ccrAA/(C)]; and two each of CC5-MRSA-[VI+fus] and CC97-MRSA-[V/VT+fus]. The SCC-borne fusidic acid resistance (fusC) gene was detected in MRSA (n = 5) and MSSA (n = 1). Some MSSA strains, CC1-MSSA-[fus+ccrAB1] and ST1278-MSSA-[ccrA1], harbored recombinase genes. A CC30-MSSA harbored ACME locus/arc-genes, while ST1278-MSSA-[ccrA1] had an ACME-III element. Enterotoxin genes were commonly carried, but tst-1 gene was found in only CC22, CC30, and CC34 strains, while pvl genes were identified in CC_(arg)2250 and CC22-MRSA-IV. Of the 51 noncoagulase staphylococci (CoNS) identified, 18 were mecA positive. Conclusion: The findings demonstrate the first report of rare strains (ST1278 MSSA, CC_(arg)2198, CC_(arg)2596, and PVL+CC_(arg)2250) in our region. Detection of MSSA with recombinase genes and ACME loci alongside mecA-positive CoNS is of clinical significance as this could provide a milieu for acquisition and transfer of SCC-elements, either with different ACME types, with fusC or the mecA gene resulting in conversion of MSSA into MRSA.

Implications of identifying the recently defined members of the Staphylococcus aureus complex S. argenteus and S. schweitzeri: a position paper of members of the ESCMID Study Group for Staphylococci and Staphylococcal Diseases (ESGS)

BACKGROUND

Staphylococcus argenteus and Staphylococcus schweitzeri, previously known as divergent Staphylococcus aureus clonal lineages, have been recently established as novel, difficult-to-delimit, coagulase-positive species within the S. aureus complex. Methicillin-resistant strains of S. argenteus are known from Australia and the UK. Knowledge of their epidemiology, medical significance and transmission risk is limited and partly contradictory, hampering definitive recommendations. There is mounting evidence that the pathogenicity of S. argenteus is similar to that of 'classical' S. aureus, while as yet no S. schweitzeri infections have been reported.

AIM

To provide decision support on whether and how to distinguish and report both species.

SOURCES

PubMed, searched for S. argenteus and S. schweitzeri.

CONTENT

This position paper reviews the main characteristics of both species and draws conclusions for microbiological diagnostics and surveillance as well as infection prevention and control measures.

IMPLICATIONS

We propose not distinguishing within the S. aureus complex for routine reporting purposes until there is evidence that pathogenicity or clinical outcome differ markedly between the different species. Primarily for research purposes, suitably equipped laboratories are encouraged to differentiate between S. argenteus and S. schweitzeri. Caution is urged if these novel species are explicitly reported. In such cases, a specific comment should be added (i.e. 'member of the S.aureus complex') to prevent confusion with less- or non-pathogenic staphylococci. Prioritizing aspects of patient safety, methicillin-resistant isolates should be handled as recommended for methicillin-resistant Staphylococcus aureus (MRSA). In these cases, the clinician responsible should be directly contacted and informed by the diagnosing microbiological laboratory, as they would be for MRSA. Research is warranted to clarify the epidemiology, clinical impact and implications for infection control of such isolates.