Toxic shock syndrome toxin 1 (TSST-1) production by staphylococci isolated from goats and presence of specific antibodies to TSST-1 in serum and milk

First human case of catheter-related blood stream infection caused by Staphylococcus schleiferi subspecies coagulans: a case report and literature review

BACKGROUND

Staphylococcus schleiferi is a gram-positive pathogenic coccus which causes canine skin and ear infections. Only four cases of human infection caused by Staphylococcus schleiferi subspecies coagulans have been reported. Herein, we present the first case of catheter-related bloodstream infection caused by S. schleiferi subspecies coagulans.

CASE PRESENTATION

A 62-year-old Japanese man was admitted to our hospital for examination of sigmoid colon tumor. During hospitalization, he had fever, shaking chills, and swelling at the peripheral venous catheter insertion site. Two sets of blood cultures were positive for S. schleiferi subspecies coagulans which was confirmed using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS), 16S ribosomal RNA sequencing and the coagulase test. The patient was successfully treated without relapse.

CONCLUSION

To our knowledge, this is the first report of catheter-related bloodstream infection caused by S. schleiferi subspecies coagulans. S. schleiferi subsp. coagulans can be pathogenic in humans, and MALDI-TOF MS can contribute to accurate identification of S. schleiferi subspecies coagulans.

The Nasal Carriage of Coagulase-Negative Staphylococci Among Animals and Its Public Health Implication

Background: The research scope toward nasal colonization of coagulase-negative staphylococci (CoNS) in animals is largely ignored for many years. Therefore, this study was conducted to investigate the nasal carriage of CoNS among different animals and its public health implication. Materials and Methods: Nasal swabs were gathered from 152 animals (36 cats, 31 dogs, 29 sheep, 32 goats, and 24 cattle). These samples were subjected for isolation and identification of CoNS by conventional bacteriological methods, then molecular confirmation was carried out using Staphylococcus genus-specific 16S rRNA PCR. All CoNS isolates were screened for the presence of antibiotic resistance (mecA and blaZ) and virulence (lukS/F-PV and tsst-1) genes. Moreover, strains carrying resistance and/or virulence genes were identified to species level by 16S rRNA gene sequencing approach. Results: CoNS were identified in 14.5% (22/152) of the examined animals, whereas the prevalence rates among different animals were 27.8%, 3.2%, 8.3%, 10.3%, and 18.8% for cats, dogs, cattle, sheep, and goats, respectively. Of all isolates, two strains (Staphylococcus epidermidis and Staphylococcus warneri) harbored mecA gene, which carried on staphylococcal cassette chromosome mec type I in S. epidermidis and type V in S. warneri, while blaZ gene has been found in one strain (Staphylococcus felis). Importantly, two isolates (S. epidermidis and S. felis) had tsst-1 gene but all of CoNS isolates were negative for Panton-Valentine leukocidin gene. The phylogenetic analysis of the obtained sequences of CoNS of the current study revealed high similarity to those of serious human clinical cases to underscore the public health significance of such isolates. Conclusion: The nasal carriage of antibiotic-resistant and toxigenic CoNS among different animals highlights the potential zoonotic link with great public health implication.

Puerperal septic shock and necrotizing fasciitis caused by staphylococcus caprae and Escherichia coli

Puerperal sepsis is one of the leading causes of maternal morbidity and mortality worldwide. Postpartum pelvic infections can cause various complications, including wound infections and necrotizing fasciitis. Several microorganisms are known to cause such infections; however, no study has reported on staphylococcus caprae, a coagulase-negative staphylococcus that is isolated frequently from animals and infrequently from human specimens, as a causative agent. Here, we report a rare case of septic shock complicated by necrotizing fasciitis after a cesarean section. This is the first report of a human isolate of S. caprae in association with puerperal sepsis and necrotizing fasciitis.

Coagulase-negative staphylococci

The definition of the heterogeneous group of coagulase-negative staphylococci (CoNS) is still based on diagnostic procedures that fulfill the clinical need to differentiate between Staphylococcus aureus and those staphylococci classified historically as being less or nonpathogenic. Due to patient- and procedure-related changes, CoNS now represent one of the major nosocomial pathogens, with S. epidermidis and S. haemolyticus being the most significant species. They account substantially for foreign body-related infections and infections in preterm newborns. While S. saprophyticus has been associated with acute urethritis, S. lugdunensis has a unique status, in some aspects resembling S. aureus in causing infectious endocarditis. In addition to CoNS found as food-associated saprophytes, many other CoNS species colonize the skin and mucous membranes of humans and animals and are less frequently involved in clinically manifested infections. This blurred gradation in terms of pathogenicity is reflected by species- and strain-specific virulence factors and the development of different host-defending strategies. Clearly, CoNS possess fewer virulence properties than S. aureus, with a respectively different disease spectrum. In this regard, host susceptibility is much more important. Therapeutically, CoNS are challenging due to the large proportion of methicillin-resistant strains and increasing numbers of isolates with less susceptibility to glycopeptides.

Comparative analysis of agr groups and virulence genes among subclinical and clinical mastitis Staphylococcus aureus isolates from sheep flocks of the Northeast of Brazil

Staphylococcus aureus is one of the most frequent mastitis causative agents in small ruminants. The expression of most virulence genes of S. aureus is controlled by an accessory gene regulator (agr) locus. This study aimed to ascertain the prevalence of the different agr groups and to evaluate the occurrence of encoding genes for cytotoxin, adhesins and toxins with superantigen activity in S. aureus isolates from milk of ewes with clinical and subclinical mastitis in sheep flocks raised for meat production The agr groups I and II were identified in both cases of clinical and subclinical mastitis. Neither the arg groups III and IV nor negative agr were found. The presence of cflA gene was identified in 100% of the isolates. The frequency of hla and lukE-D genes was high - 77.3 and 82.8%, respectively and all isolates from clinical mastitis presented these genes. The sec gene, either associated to tst gene or not, was identified only in isolates from subclinical mastitis. None of the following genes were identified: bbp, ebpS, cna, fnbB, icaA, icaD, bap, hlg, lukM-lukF-PV and se-a-b-d-e.

Phenotype characterization of Staphylococcus species strains isolated from buffalo (Bubalus bubalis) milk

The objective of the current study was to isolate and identify phenotypes of Staphylococcus spp. strains derived from buffalo ( Bubalus bubalis) milk. A total of 548 milk samples from 137 buffalo were cultured in Columbia agar enriched with 5% defibrinated sheep blood. Determination of the capacity of Staphylococcus aureus to produce enterotoxins A–D and toxic shock syndrome toxin-1 (TSST-1) was achieved by reverse passive latex agglutination (RPLA). Antimicrobial sensitivity of S. aureus strains was evaluated using the disk diffusion technique, and β-lactamase detection was achieved using the chromogenic test with paper discs impregnated with nitrocefin. From all the mammary quarters examined, 36 (10.8%) were positive for Staphylococcus spp., 83.3% were coagulase-negative staphylococcus (CNS), 11.1% were coagulase-positive staphylococcus (CPS), and 5.6% were of CPS+CNS positive. All isolates of S. aureus produced at least 1 toxin and 5 out of 6 isolates (83.0%) produced β-lactamase. One hundred percent of S. aureus isolates were sensitive to methicillin and amoxicillin + clavulanic acid, and resistant to ampicillin, penicillin, and oxacillin. Analysis of the results obtained in the current study highlight the epidemiologic importance of buffalo milk regarding the production of enterotoxins and TSST-1 and the potential risk to public health.

Prevalence of staphylococcal enterotoxins, toxin genes and genetic-relatedness of foodborne Staphylococcus aureus strains isolated in the Marmara Region of Turkey

Staphylococcus aureus is a major foodborne pathogen and it has the ability to produce a number of extracellular toxins. We analyzed 1070 food samples obtained from retail markets and dairy farms in the Marmara Region of Turkey for the presence of S. aureus. Out of 147 isolates, 92 (62.6%) were enterotoxigenic. PCR was used to investigate the presence of staphylococcal enterotoxin genes (sea, seb, sec, sed, see, seg, seh, sei, sej, sek, sel, sem, sen, seo, sep, seq and seu), exfoliative toxin genes (eta and etb) and the toxic-shock syndrome toxin gene (tst). The PCR results showed that 53.3% of the isolates contained staphylococcal enterotoxin-like (SEl) toxin genes (seg, seh, sei, sej, sek, sel, sem, sen, seo, sep, seq and seu) which were more frequent than classical enterotoxin genes (sea to see). Furthermore, seo, sei, sem, seg, seu and sec were found in 37.0, 32.7, 30.4, 29.3, 29.3 and 27.2% of the isolates, respectively. The tst gene was detected and confirmed by DNA sequencing in 9 isolates. The presence of eta and etb were not found in the isolates. Enterotoxigenic capabilities of isolates with SEA-SEE were investigated by ELISA. Enterotoxigenic S. aureus isolates produced one to three enterotoxins, with the most frequently produced types being enterotoxin A and C. There was a correlation of 72.1% between production of a specific toxin and the presence of the respective genes. PFGE analysis was used to identify genetic-relatedness of enterotoxigenic S. aureus isolates and the results revealed that 13 groups of isolates from different or the same origin that contained the same genes showed 100% homology with indistinguishable band patterns. The other enterotoxigenic isolates showed related band patterns with 72-86% homology in sea-, 61-90% homology in sec-, 80-96% homology in seh-, and 69-96% homology in sep-positive isolates. To our knowledge, this is the first study to examine enterotoxins and related gene contents of S. aureus food isolates in the Marmara Region of Turkey.

An Enterotoxin-Bearing Pathogenicity Island in Staphylococcus epidermidis

Cocolonization of human mucosal surfaces causes frequent encounters between various staphylococcal species, creating opportunities for the horizontal acquisition of mobile genetic elements. The majority of Staphylococcus aureus toxins and virulence factors are encoded on S. aureus pathogenicity islands (SaPIs). Horizontal movement of SaPIs between S. aureus strains plays a role in the evolution of virulent clinical isolates. Although there have been reports of the production of toxic shock syndrome toxin 1 (TSST-1), enterotoxin, and other superantigens by coagulase-negative staphylococci, no associated pathogenicity islands have been found in the genome of Staphylococcus epidermidis, a generally less virulent relative of S. aureus. We show here the first evidence of a composite S. epidermidis pathogenicity island (SePI), the product of multiple insertions in the genome of a clinical isolate. The taxonomic placement of S. epidermidis strain FRI909 was confirmed by a number of biochemical tests and multilocus sequence typing. The genome sequence of this strain was analyzed for other unique gene clusters and their locations. This pathogenicity island encodes and expresses staphylococcal enterotoxin C3 (SEC3) and staphylococcal enterotoxin-like toxin L (SElL), as confirmed by quantitative reverse transcription-PCR (qRT-PCR) and immunoblotting. We present here an initial characterization of this novel pathogenicity island, and we establish that it is stable, expresses enterotoxins, and is not obviously transmissible by phage transduction. We also describe the genome sequence, excision, replication, and packaging of a novel bacteriophage in S. epidermidis FRI909, as well as attempts to mobilize the SePI element by this phage.

Toxigenicity in Staphylococcus aureus and Coagulase-Negative Staphylococci: Epidemiological and Molecular Aspects

Representatives of the Staphylococcus genus are the most common pathogens found in hospital environments, and they are etiological agents for a large variety of infections. Various virulence factors are responsible for the symptoms and severity of infections caused by Staphylococcus aureus. Among them are staphylococcal enterotoxins (SEs), which cause staphylococcal food poisoning, and toxic shock syndrome toxin-1 (TSST-1). Some reports indicate that TSST-1 and staphylococcal enterotoxins are also produced by coagulase-negative staphylococci (CNS). The present review aimed to discuss general aspects of staphylococcal toxins as well as the epidemiology, genetics and detection of toxins in Staphylococcus aureus and coagulase-negative staphylococci, since these microorganisms are becoming more and more frequent in nosocomial infections.

Detection of enterotoxin and toxic shock syndrome toxin 1 genes in Staphylococcus, with emphasis on coagulase-negative staphylococci

The detection of staphylococcal enterotoxins is decisive for the confirmation of an outbreak and for the determination of the enterotoxigenicity of strains. Since the recognition of their antigenicity, a large number of serological methods for the detection of enterotoxins in food and culture media have been proposed. Since immunological methods require detectable amounts of toxin, molecular biology techniques represent important tools in the microbiology laboratory. In the present study, polymerase chain reaction (PCR) was used to identify genes responsible for the production of enterotoxins and toxic shock syndrome toxin 1 (TSST-1) in S. aureus and coagulase-negative staphylococci (CNS) isolated from patients and the results were compared with those obtained by the reverse passive latex agglutination (RPLA) assay. PCR detection of toxin genes revealed a higher percentage of toxigenic S. aureus strains (46.7%) than the RPLA method (38.3%). Analysis of the toxigenic profile of CNS strains showed that 26.7% of the isolates produced some type of toxin, and one or more toxin-specific genes were detected in 40% of the isolates. These results suggests the need for further studies in order to better characterize the pathogenic potential of CNS and indicate that attention should be paid to the toxigenic capacity of this group of microorganisms.

Study of virulence factors in coagulase-negative staphylococci isolated from newborns

Coagulase-negative staphylococci (CNS) have been identified as the etiological agent in various infections and are currently the microorganisms most frequently isolated in nosocomial infections. However, little is known about the virulence factors produced by CNS that contribute to the pathogenesis of infections caused by these microorganisms. The study of CNS isolated from infectious processes of newborns hospitalized in the Neonatal Unit of the Hospital of the Botucatu Medical School, UNESP, indicated Staphylococcus epidermidis as the most frequently isolated species (77.8%), which was also associated with clinically significant situations. The analysis of virulence factors revealed the production of slime in 20 (17.1%) of all CNS samples isolated and the synthesis of a broad spectrum of enzymes and toxins, including hemolysins (19.6%), lipase (17.1%), lecithinase (3.4%), DNAse (15.4%), thermonuclease (7.7%), and enterotoxin A, B or C (37.6%). Taking into consideration that the etiological importance of CNS has often been neglected, the present investigation confirmed that these microorganisms should not be ignored or classified as mere contaminants.

Survey of genes encoding staphylococcal enterotoxins, toxic shock syndrome toxin 1, and exfoliative toxins in members of the Staphylococcus sciuri group

Genes encoding staphylococcal enterotoxins (sea to see, seg, and seh), toxic shock syndrome toxin 1 (tst), and exfoliative toxins (eta and etb) were not detected in a large panel of 48 Staphylococcus sciuri group isolates tested. This strongly suggests that production of the staphylococcal exotoxins by these bacteria is highly unlikely.

Occurrence and clonal relatedness of sec/tst-gene positive Staphylococcus aureus isolates of quartermilk samples of cows suffering from mastitis

AIMS

To investigate the prevalence of sec/tst-gene positive Staphylococcus aureus in bovine mastitis and to get information about the clonal relatedness of these clinical isolates.

METHODS AND RESULTS

A total of 533 Staph. aureus strains isolated from bovine mastitic quartermilk samples at 493 randomized dairy farms in Hessia, Germany, from January 1997 until June 1998 were examined for enterotoxin C (sec) gene and toxic shock syndrome toxin (tst) gene by multiplex polymerase chain reaction. Fifty-three (9.3%) of the strains were sec/tst-gene positive. Phenotypic TSST-1 production was found in all positive strains by reversed passive latex agglutination test. With DNA macrorestriction analysis, sec/tst-gene positive strains were divided into five different macrorestriction types. Type I (10 isolates) and III (40 isolates) were found to be the predominant types in terms of frequency of isolation in the investigated area. These DNA macrorestriction types differed in only two bands in the 500 and 270 bp region.

CONCLUSIONS

Closely related Staph. aureus strains seem to be responsible for an unusual large proportion of bovine mastitis cases in geographically widely distinct locations.

SIGNIFICANCE AND IMPACT OF THE STUDY

This is one of the first reports about the relatedness of sec/tst-gene positive Staph. aureus clinical isolates from bovine mastitis.

Human isolates of Staphylococcus caprae: association with bone and joint infections

Staphylococcus caprae is a coagulase-negative, DNase-positive member of the genus Staphylococcus usually associated with goats, but since 1991 a few laboratories have reported isolating the organism from human clinical specimens. We report on the isolation of 14 strains from human specimens and note that 10 strains were obtained from patients with bone and joint infections. Nine of the 10 infections started with traumatic fractures, and the other was a case of mastoiditis. Seven of these 10 infections were in patients with orthopedic prostheses, which appears to be a risk factor. Three of the 14 strains were from transplant patients. For three of the patients, S. caprae was the only organism isolated. S. caprae may be misidentified because it is not represented in the current MicroScan or Vitek identification systems which are in use in many laboratories, but the organism can be differentiated by a few biochemical tests. S. caprae produces positive results for DNase, pyrrolidonyl aminopeptidase, and acid production from mannitol and maltose; it produces negative results for ornithine decarboxylase and tube coagulase.

Detection of enterotoxins and TSST-1 secreted by Staphylococcus aureus isolated from ruminant mastitis. Comparison of ELISA and immunoblot

The production of staphylococcal enterotoxins (SE) and toxic shock syndrome toxin-1 (TSST-1) was studied in 81 strains of Staphylococcus aureus isolated from cases of mastitis in cattle, goats and sheep. SE and TSST-1 were detected by two techniques: ELISA double antibody sandwich, and an immunoblot technique combined with a semiautomated electrophoresis system. More Staph. aureus strains isolated from sheep produced enterotoxins than those from goats and cattle. SEC was the predominant type in all isolates from these animal species. The highest proportion of strains producing TSST-1 were obtained from sheep, twice as many as those from goats or cows. The two techniques gave similar results, as all the strains positive by immunoblot were also positive by ELISA, and only three were positive by ELISA but negative by immunoblot.

Production of staphylococcal enterotoxins and TSST-1 by coagulase negative staphylococci isolated from ruminant mastitis

The production of staphylococcal enterotoxins (SE) and toxic shock syndrome toxin-1 by 40 coagulase negative staphylococci isolated from sheep, goat and cow mastitis was studied. Both ELISA double sandwich and Western blot were used to detect the production of these toxins. Only two strains of S. xylosus were enterotoxigenic, producing SEC. TSST-1 was seen to be produced by 5 strains of S. xylosus, 1 S. sciuri and 2 S. epidermidis. Results obtained by ELISA and by Western blot agreed in all cases except in one strain of S. epidermidis which was only positive using ELISA.

Enterotoxin and toxic shock syndrome toxin-one production by staphylococci isolated from mastitis in sheep

From 160 staphylococci isolated from ovine mastitis, 125 were identified as coagulase-positive staphylococci (CPS) and 35 as coagulase-negative staphylococci (CNS). Of these, 108 (87.8%) S. aureus produced at least one of the staphylococcal enterotoxins (SE) described. However, no CNS was found to be enterotoxigenic. Enterotoxin C (SEC) was the type most frequently produced. TSST-1 was shown to be produced by 91 (74.0%) of S. aureus, almost invariably in combination with SEC. Three CNS strains were also found to produce TSST-1 (two strains of S. xylosus and one strain of S. epidermidis).