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We observed bacterial or fungal coinfections in COVID-19 patients admitted between March 1 and April 18, 2020 (152 of 4,267, 3.6%). Among these patients, mortality was 57%; 74% were intubated; 51% with bacteremia had central venous catheters. Time to culture positivity was 6-7 days, and 79% had received prior antibiotics. Metallo-ß-lactamase-producing E. cloacae coinfections occurred in 5 patients.
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Antibacterianos/uso terapêutico , Bacteriemia , COVID-19 , Coinfecção , Micoses , SARS-CoV-2/isolamento & purificação , Bacteriemia/diagnóstico , Bacteriemia/epidemiologia , Bacteriemia/terapia , COVID-19/epidemiologia , COVID-19/microbiologia , COVID-19/terapia , Cateteres Venosos Centrais/microbiologia , Cateteres Venosos Centrais/estatística & dados numéricos , Coinfecção/epidemiologia , Coinfecção/microbiologia , Coinfecção/virologia , Farmacorresistência Bacteriana , Feminino , Humanos , Masculino , Técnicas Microbiológicas/métodos , Técnicas Microbiológicas/estatística & dados numéricos , Pessoa de Meia-Idade , Micoses/diagnóstico , Micoses/epidemiologia , Micoses/terapia , New York/epidemiologia , Avaliação de Processos e Resultados em Cuidados de Saúde , Respiração Artificial/estatística & dados numéricos , Índice de Gravidade de DoençaAssuntos
COVID-19/microbiologia , Infecções por Enterobacteriaceae/microbiologia , Enterobacteriaceae/metabolismo , beta-Lactamases/metabolismo , Idoso , Antibacterianos/uso terapêutico , Gestão de Antimicrobianos , COVID-19/terapia , Enterobacteriáceas Resistentes a Carbapenêmicos/isolamento & purificação , Cateteres Venosos Centrais , Coinfecção , Enterobacter cloacae/efeitos dos fármacos , Enterobacter cloacae/isolamento & purificação , Enterobacter cloacae/metabolismo , Enterobacteriaceae/isolamento & purificação , Infecções por Enterobacteriaceae/terapia , Infecções por Enterobacteriaceae/virologia , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Cidade de Nova Iorque , Respiração ArtificialRESUMO
The emergence of drug-resistant Staphylococcus aureus is responsible for high morbidity and mortality worldwide. New therapeutic options are needed to fight the increasing antimicrobial resistance among S. aureus in the clinical setting. We, therefore, characterized the in silico absorption, distribution, metabolism, elimination, and toxicity (ADMET) and in vitro antimicrobial activity of 5-nitro-2-thiophenecarbaldehyde N-((E)-(5-nitrothienyl)methylidene)hydrazone (KTU-286) against drug-resistant S. aureus strains with genetically defined resistance mechanisms. The antimicrobial activity of KTU-286 was determined by CLSI recommendations. The ADMET properties were estimated by using in silico modeling. The activity on biofilm integrity was examined by crystal violet assay. KTU-286 demonstrated low estimated toxicity and low skin permeability. The highest antimicrobial activity was observed among pan-susceptible (Pan-S) S. aureus (minimal inhibitory concentration (MIC) 0.5-2.0 µg/mL, IC50 = 0.460 µg/mL), followed by vancomycin resistant S. aureus (VRSA) (MIC 4.0 µg/mL, IC50 = 1.697 µg/mL) and methicillin-resistant S. aureus (MRSA) (MIC 1.0-16.0 µg/mL, IC50 = 2.282 µg/mL). KTU-286 resulted in significant (p < 0.05) loss of S. aureus biofilm integrity in vitro. Further studies are needed for a better understanding of safety, synergistic relationship, and therapeutic potency of KTU-286.
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PURPOSE: Inappropriate vancomycin for febrile neutropenia (FN) is an ideal antimicrobial stewardship target. To improve vancomycin prescribing, we instituted a multifaceted intervention, including an educational guideline with audit for compliance; an antibiotic use audit; and an assessment of local burden of methicillin-resistant Staphylococcus aureus (MRSA) colonization and infection. MATERIALS AND METHODS: We conducted a quasi-experimental pre-post intervention review of vancomycin initiation for FN on a 32-bed hematology/oncology unit. A retrospective chart review was conducted from November 2015 to May 2016 (preintervention period). In January 2017, we implemented an institutional FN guideline emphasizing criteria for appropriate use. Vancomycin audit was conducted from February 2017 to October 2017 (postintervention period). The primary outcome was appropriateness of vancomycin initiation. We then compared average antibiotic use (days of therapy per 1,000 patient days) for vancomycin and cefepime before and after intervention. Finally, unit-wide MRSA screening cultures were obtained upon admission and bimonthly for 6 weeks (October 2, 2017, to November 9, 2017). Screened patients were followed for 12 months for clinical MRSA infection. RESULTS: Forty-three (49%) of 88 preintervention patients were started on empiric vancomycin appropriately, compared with 59 (66%) of 90 postintervention patients (P = .02). There was a significant decrease in vancomycin use after intervention. Six (7.1%) of 85 patients screened positive for MRSA colonization. During the 12-month follow-up, no colonized patients developed clinical MRSA infections (positive predictive value, 0.0%). Of the 79 noncolonized patients, 2 developed a clinically significant infection (negative predictive value, 97.5%). CONCLUSION: Guideline-focused education can improve vancomycin appropriateness in FN and should be bundled with education and feedback about local MRSA epidemiology and antibiotic use rates for maximal stewardship impact.
Assuntos
Neutropenia Febril , Staphylococcus aureus Resistente à Meticilina , Antibacterianos/uso terapêutico , Neutropenia Febril/tratamento farmacológico , Neutropenia Febril/epidemiologia , Humanos , Estudos Retrospectivos , Staphylococcus aureusRESUMO
Granulibacter bethesdensis is a Gram-negative bacillus described as a pathogen exclusively in patients with chronic granulomatous disease, a phagocytic disorder that impairs the ability to clear catalase-producing organisms. Granulibacter usually causes chronic and recurrent lymphadenopathies. We report the fatal case of a 4-year-old boy with chronic granulomatous disease, who presented with sepsis after a few days of abdominal pain and diarrhea.
Assuntos
Acetobacteraceae , Infecções por Bactérias Gram-Negativas , Doença Granulomatosa Crônica , Sepse , Pré-Escolar , Coagulação Intravascular Disseminada , Evolução Fatal , Doença Granulomatosa Crônica/complicações , Doença Granulomatosa Crônica/genética , Humanos , MasculinoRESUMO
PROBLEM: Genital tract secretions inhibit Escherichia coli (E. coli) through antimicrobial peptides (AMP) secreted by the host and vaginal microbiota. However, there are limited data against group B Streptococcus (GBS). METHOD OF STUDY: Group B Streptococcus were incubated with cervico-vaginal lavage (CVL) samples from healthy non-pregnant women (n = 12) or synthetic AMP and monitored for bacterial growth using a turbidimetric approach. E. coli inhibitory activity was determined by a colony-forming unit assay. RESULTS: None of the CVL samples inhibited GBS. The human neutrophil peptide-1 and human defensin 5 inhibited GBS growth by ≥80% at concentrations ≥20 µg/mL and ≥50 µg/mL, respectively, while human beta-defensin 2 and LL-37 did not inhibit at highest concentration tested (100 µg/mL). In contrast, all AMP inhibited E. coli. CONCLUSIONS: Antimicrobial peptides may protect against E. coli colonization but have more limited activity against GBS. Future studies will focus on augmenting host defense with specific AMP to prevent genitourinary infection with these pathogenic organisms.
Assuntos
Peptídeos Catiônicos Antimicrobianos/metabolismo , Secreções Corporais/metabolismo , Genitália Feminina/metabolismo , Infecções Estreptocócicas/imunologia , Streptococcus/imunologia , Adulto , Defensinas/metabolismo , Escherichia coli/crescimento & desenvolvimento , Feminino , Genitália Feminina/imunologia , Genitália Feminina/microbiologia , Humanos , Imunidade Inata , Streptococcus/crescimento & desenvolvimento , Ducha VaginalRESUMO
BACKGROUND: The incidence of community-onset (CO) methicillin-resistant Staphylococcus aureus (MRSA) bacteremia rose from the late 1990s through the 2000s. However, hospital-onset (HO) MRSA rates have recently declined in the United States and Europe. METHODS: Data were abstracted from infection prevention databases between 1 January 2008 and 31 December 2011 at 5 US academic medical centers to determine the number of single-patient blood cultures positive for MRSA and methicillin-susceptible S. aureus (MSSA) per calendar year, stratified into CO and HO infections. RESULTS: Across the 5 centers, 4171 episodes of bacteremia were identified. Center A (Los Angeles, California) experienced a significant decline in CO-MRSA bacteremia rates (from a peak in 2009 of 0.42 to 0.18 per 1000 patient-days in 2011 [P = .005]), whereas CO-MSSA rates remained stable. Centers B (San Francisco, California), D (Chicago, Illinois), and E (Raleigh-Durham, North Carolina) experienced a stable incidence of CO-MRSA and CO-MSSA bacteremia. In contrast, at center C (New York, New York), the incidence of CO-MRSA increased >3-fold (from 0.11 to 0.34 cases per 1000 patient-days [P < .001]). At most of the sites, HO-MRSA decreased and HO-MSSA rates were stable. USA300 accounted for 52% (104/202) of genotyped MRSA isolates overall, but this varied by center, ranging from 35% to 80%. CONCLUSIONS: CO-MRSA rates and the contribution of USA300 MRSA varied dramatically across diverse geographical areas in the United States. Enhanced infection control efforts are unlikely to account for such variation in CO infection rates. Bioecological and clinical explanations for geographical differences in CO-MRSA bacteremia rates merit further study.
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Centros Médicos Acadêmicos , Bacteriemia , Infecção Hospitalar , Infecções Estafilocócicas/epidemiologia , Infecções Estafilocócicas/microbiologia , Staphylococcus aureus , Adolescente , Adulto , Criança , Pré-Escolar , Infecções Comunitárias Adquiridas/epidemiologia , Infecções Comunitárias Adquiridas/microbiologia , Bases de Dados Factuais , Genes Bacterianos , Genótipo , História do Século XXI , Humanos , Incidência , Lactente , Recém-Nascido , Staphylococcus aureus Resistente à Meticilina/classificação , Staphylococcus aureus Resistente à Meticilina/genética , Staphylococcus aureus Resistente à Meticilina/isolamento & purificação , Tipagem de Sequências Multilocus , Infecções Estafilocócicas/história , Staphylococcus aureus/classificação , Staphylococcus aureus/genética , Staphylococcus aureus/isolamento & purificação , Estados Unidos/epidemiologia , Adulto JovemRESUMO
Matrix-assisted laser desorption-ionization time of flight mass spectrometry (MALDI-TOF MS) is a rapid and accurate method of identifying microorganisms. Throughout Europe, it is already in routine use but has not yet been widely implemented in the United States, pending FDA approval. Here, we describe two medically complex patients at a large tertiary-care academic medical center with recurring bacteremias caused by distinct but related species. Bacterial identifications were initially obtained using the Vitek-2 system with the GPI card for Enterococcus and the API system for staphylococci. Initial results misled clinicians as to the source and proper management of these patients. Retrospective investigation with MALDI-TOF MS clarified the diagnosis by identifying a single microorganism as the pathogen in each case. To our knowledge, this is one of the first reports in the United States demonstrating the use of MALDI-TOF MS to facilitate the clinical diagnosis in patients with recurrent bacteremias of unclear source.
Assuntos
Bacteriemia/diagnóstico , Bacteriemia/microbiologia , Técnicas Bacteriológicas/métodos , Enterococcus/isolamento & purificação , Infecções por Bactérias Gram-Positivas/diagnóstico , Infecções por Bactérias Gram-Positivas/microbiologia , Espectrometria de Massas por Ionização e Dessorção a Laser Assistida por Matriz/métodos , Adulto , Feminino , Humanos , Masculino , Recidiva , Centros de Atenção Terciária , Estados Unidos , Adulto JovemRESUMO
OBJECTIVE: Genital tract secretions exhibit bactericidal activity against Escherichia coli. We hypothesized that this defense may be modulated during pregnancy. STUDY DESIGN: Secretions were collected by vaginal swab from 70 pregnant women (35-37 weeks' gestation) and 35 nonpregnant controls. We mixed E coli with swab eluants or control buffer and colonies enumerated to measure bactericidal activity. Cytokines, chemokines, and antimicrobial peptides were quantified by multiplex or enzyme-linked immunosorbent assay. RESULTS: Pregnant women had significantly greater bactericidal activity, higher concentrations of proinflammatory cytokines, and lower levels of beta defensins compared to controls. Seven (10%) pregnant and 8 (23%) nonpregnant women were vaginally colonized with E coli; colonization was inversely associated with bactericidal activity. CONCLUSION: The soluble mucosal immune environment is altered in pregnancy. We speculate that the observed changes may protect against colonization and ascending infection and could provide a biomarker to identify pregnant women at risk for infectious complications including preterm birth.
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Quimiocinas/metabolismo , Citocinas/metabolismo , Escherichia coli/crescimento & desenvolvimento , Vagina/imunologia , Adulto , Feminino , Humanos , Gravidez , Vagina/metabolismo , Esfregaço VaginalRESUMO
UNLABELLED: Annexin A5 (AnxA5) has a high affinity for phosphatidylserine. The protein is widely used to detect apoptotic cells because phosphatidylserine, a phospholipid that is normally present in the inner leaflets of cytoplasmic membranes, becomes translocated to the outer leaflets during programmed cell death. Here we report the novel observation that AnxA5 binds to Gram-negative bacteria via the lipid A domain of lipopolysaccharide (LPS). Binding of AnxA5 to bacteria was measured quantitatively, confirmed by fluorescence microscopy, and found to be inhibited by antibodies against lipid A. AnxA5 also bound to purified dot-blotted LPS and lipid A. Through ellipsometry, we found that the binding of AnxA5 to purified LPS was calcium dependent and rapid and showed a high affinity-characteristics similar to those of AnxA5 binding to phosphatidylserine. Initial functional studies indicated that AnxA5 can affect LPS activities. AnxA5 inhibited LPS-mediated gelation in the Limulus amebocyte lysate assay. Incubation of LPS with the protein reduced the quantity of tumor necrosis factor alpha (TNF-α) released by cultured monocytes compared to that released upon incubation with LPS alone. Initial in vivo experiments indicated that injection of mice with LPS preincubated with AnxA5 produced serum TNF-α levels lower than those seen after injection of LPS alone. These data demonstrate that AnxA5 binds to LPS and open paths to investigation of the potential biological and therapeutic implications of this interaction. IMPORTANCE: AnxA5 is highly expressed in cells that have a barrier function-including, among others, vascular endothelium, placental trophoblasts, and epithelial cells lining bile ducts, renal tubules, mammary ducts, and nasal epithelium. The protein has been well characterized for its binding to phospholipid bilayers that contain phosphatidylserine. This report of a previously unrecognized activity of AnxA5 opens the door to investigation of the possibility that this binding may have biological and therapeutic ramifications. In view of the tissue expression of the protein, the present results suggest the possibility that AnxA5 plays a role in modulating the host defense against lipopolysaccharide at these anatomic sites, where cells may interface with microorganisms. These results also raise the intriguing possibility that AnxA5 or analogous proteins or peptides could provide novel approaches to addressing the difficult clinical problem of Gram-negative sepsis.
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Anexina A5/metabolismo , Bactérias/metabolismo , Endotoxinas/antagonistas & inibidores , Endotoxinas/metabolismo , Lipopolissacarídeos/antagonistas & inibidores , Lipopolissacarídeos/metabolismo , Animais , Cálcio/metabolismo , Linhagem Celular , Endotoxinas/toxicidade , Feminino , Cinética , Teste do Limulus , Lipopolissacarídeos/toxicidade , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Microscopia de Fluorescência , Monócitos/efeitos dos fármacos , Monócitos/imunologia , Fator de Necrose Tumoral alfa/sangue , Fator de Necrose Tumoral alfa/metabolismoRESUMO
Nitric oxide (NO) is a critical component of host defense against invading pathogens; however, its therapeutic utility is limited due to a lack of practical delivery systems. Recently, a NO-releasing nanoparticulate platform (NO-np) was shown to have in vitro broad-spectrum antimicrobial activity and in vivo pre-clinical efficacy in a dermal abscess model. To extend these findings, both topical (TP) and intralesional (IL) NO-np administration was evaluated in a MRSA intramuscular murine abscess model and compared with vancomycin. All treatment arms accelerated abscess clearance clinically, histologically, and by microbiological assays on both days 4 and 7 following infection. However, abscesses treated with NO-np via either route demonstrated a more substantial, statistically significant decrease in bacterial survival based on colony forming unit assays and histologically revealed less inflammatory cell infiltration and preserved muscular architecture. These data suggest that the NO-np may be an effective addition to our armament for deep soft tissue infections.
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Abscesso/tratamento farmacológico , Antibacterianos/administração & dosagem , Portadores de Fármacos/química , Nanopartículas/química , Óxido Nítrico/administração & dosagem , Piomiosite/tratamento farmacológico , Abscesso/microbiologia , Animais , Antibacterianos/química , Sistemas de Liberação de Medicamentos , Avaliação Pré-Clínica de Medicamentos , Feminino , Humanos , Staphylococcus aureus Resistente à Meticilina/efeitos dos fármacos , Staphylococcus aureus Resistente à Meticilina/fisiologia , Camundongos , Camundongos Endogâmicos BALB C , Óxido Nítrico/química , Piomiosite/microbiologiaRESUMO
Nitric oxide (NO) plays a vital role in mammalian host defense through a variety of mechanisms. In particular, NO can oxidize to form reactive nitrogen species or interact with protein thiols and metal centers, blocking essential microbial processes. S-nitrosoglutathione (GSNO), a potent NO donor formed by the interaction of NO with intracellular glutathione (GSH), is a major factor in this pathway and is considered one of the strongest naturally occurring nitrosating agent. We previously described the broad-spectrum antimicrobial activity of a nanoparticulate platform capable of controlled and sustained release of NO (NO-np). Interestingly, in vivo efficacy of the NO-np surpassed in vitro data generated. We hypothesized that the enhanced activity was in part achieved via the interaction between the generated NO and available GSH, forming GSNO. In the current study, we investigated the efficiency of NO-np to form GSNO in the presence of GSH was evaluated, and assessed the antimicrobial activity of the formed GSNO against methicillin resistant Staphylococcus aureus (MRSA), Escherichia coli, Klebsiella pneumoniae, and Pseudomonas aeruginosa. When GSH was combined with NO-np, GSNO was rapidly produced and significant concentrations of GSNO were maintained for >24h. The GSNO generated was more effective compared to NO-np alone against all bacterial strains examined, with P. aeruginosa being the most sensitive and K. pneumoniae the most resistant. We conclude that the combination of NO-np with GSH is an effective means of generating GSNO, and presents a novel approach to potent antimicrobial therapy.
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Antibacterianos/farmacologia , Nanopartículas/química , Óxido Nítrico/química , S-Nitrosoglutationa/farmacologia , Escherichia coli/efeitos dos fármacos , Glutationa/química , Klebsiella pneumoniae/efeitos dos fármacos , Staphylococcus aureus Resistente à Meticilina/efeitos dos fármacos , Testes de Sensibilidade Microbiana , Óxido Nítrico/farmacologia , Doadores de Óxido Nítrico/química , Doadores de Óxido Nítrico/farmacologia , Pseudomonas aeruginosa/efeitos dos fármacos , S-Nitrosoglutationa/químicaRESUMO
The rapidly evolving crisis of antibiotic resistance among microorganisms has contributed to the rise of patient morbidity and mortality from nosocomial and community-acquired infections. Therefore, innovative antimicrobial technology targeting mechanisms to which the bacteria are unlikely to evolve resistance is urgently needed. We have previously described a nitric oxide-releasing nanoparticle (NO-np) with efficacy against methicillin-resistant Staphylococcus aureus (MRSA) and Acinetobacter baumannii in vitro and in murine wound and abscess models. Although the prior findings suggest that the NO-np can be a useful therapeutic for skin and soft tissue infections, the antimicrobial spectrum of NO-np has yet to be fully elucidated. In the current study, we investigated the efficacy of a NO-np against several Gram-positive and -negative clinical isolates. We found that the NO-np were uniformly active against all of the Streptococcus pyogenes, Enterococcus faecalis, Klebsiella pneumoniae, Escherichia coli, and Pseudomonas aeruginosa clinical isolates examined, including strains that were both sensitive and resistant to commonly used antibiotics. We concluded that the NO-np have the potential to serve as a novel broad spectrum antimicrobial agent.
Assuntos
Antibacterianos/toxicidade , Portadores de Fármacos/farmacologia , Bactérias Gram-Negativas/efeitos dos fármacos , Bactérias Gram-Positivas/efeitos dos fármacos , Nanopartículas/toxicidade , Óxido Nítrico/toxicidade , Bactérias Gram-Negativas/isolamento & purificação , Infecções por Bactérias Gram-Negativas/microbiologia , Bactérias Gram-Positivas/isolamento & purificação , Infecções por Bactérias Gram-Positivas/microbiologia , Humanos , Testes de Sensibilidade Microbiana , Viabilidade Microbiana , Fatores de TempoRESUMO
We report the results of the 3M rapid detection respiratory syncytial virus (RSV) assay. This study includes pediatric patient results from nasopharyngeal swabs submitted from October to December 2009. There was a sensitivity of 74% and specificity approaching 100% compared to the PCR-based xTAG respiratory viral panel.
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Técnicas de Diagnóstico Molecular/métodos , Kit de Reagentes para Diagnóstico , Infecções por Vírus Respiratório Sincicial/diagnóstico , Vírus Sincicial Respiratório Humano/isolamento & purificação , Humanos , Lactente , Nasofaringe/virologia , Sensibilidade e EspecificidadeRESUMO
Chronic bacterial colonisation or infection of wound is one of the major factors interfering proper wound healing, especially in diabetic foot ulcers. This study assesses the potential antimicrobial properties of maggots in vitro. This is a prospective randomised experimental study. Complete lysis of methicillin-resistant Staphylococcus aureus, Pseudomonas aeruginosa, vancomycin-resistant Enterococcus and Candida albicans cultures in the area of maggot application was observed 24 hours after application of live maggots in all culture plates and was confirmed by Gram staining. This lysis persisted for more than 5 days after the maggot application. Complete lysis of the bacterial or fungal cultures in the area of maggot application provides convincing evidence for the antimicrobial property of maggots. This effect has a significant implication in management of diabetic foot ulcers and vascular ulcers.
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Bacteriólise , Controle de Infecções/métodos , Larva , Infecção dos Ferimentos/microbiologia , Infecção dos Ferimentos/terapia , Animais , Infecções Bacterianas/terapia , Candida albicans , Doença Crônica , Desbridamento/métodos , Dípteros , Enterococcus , Humanos , Micoses/microbiologia , Micoses/terapia , Estudos Prospectivos , Pseudomonas aeruginosa , Staphylococcus aureus , Resistência a Vancomicina , Cicatrização , Infecção dos Ferimentos/patologiaRESUMO
The role of Panton-Valentine leukocidin (PVL) in Staphylococcus aureus infections is controversial. We used a mouse model of skin infection to compare the virulence of methicillin-resistant S. aureus (MRSA) and methicillin-susceptible S. aureus (MSSA) strains with different levels of PVL production. Differences in PVL production were not associated with mutations in the genes lukS-PV and lukF-PV. However, MSSA and MRSA strains that produced high levels of PVL caused larger skin abscesses, higher bacterial burdens, and more tissue inflammation than did low-PVL-producing strains. Together, these data suggest that (1) the effect of PVL on the pathogenesis of staphylococcal infection may depend on the level of toxin produced and (2) many strains of MSSA that cause soft-tissue infections produce higher levels of PVL than do MRSA strains.
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Toxinas Bacterianas/metabolismo , Exotoxinas/metabolismo , Leucocidinas/metabolismo , Staphylococcus aureus Resistente à Meticilina/patogenicidade , Infecções Cutâneas Estafilocócicas/microbiologia , Infecção da Ferida Cirúrgica/microbiologia , Animais , Modelos Animais de Doenças , Eletroforese em Gel de Campo Pulsado , Feminino , Genótipo , Humanos , Staphylococcus aureus Resistente à Meticilina/isolamento & purificação , Camundongos , Cidade de Nova Iorque , Staphylococcus aureus/efeitos dos fármacos , Staphylococcus aureus/patogenicidade , VirulênciaRESUMO
Staphylococcal enterotoxins (SE) can cause toxin-mediated disease, and those that function as superantigens are implicated in the pathogenesis of allergic diseases. The prevalence of 19 enterotoxin genes was determined by PCR in clinical S. aureus strains derived from wounds (108) and blood (99). We performed spa typing and multilocus sequence typing (MLST) to determine clonal origin, and for selected strains staphylococcal enterotoxin B (SEB) production was measured by enzyme-linked immunosorbent assay. Strains carried a median of five SE genes. For most SE genes, the prevalence rates among methicillin-resistant and methicillin-sensitive S. aureus isolates, as well as wound- and blood-derived isolates, did not differ. At least one SE gene was detected in all except two S. aureus isolates (>99%). Complete egc clusters were found in only 11% of S. aureus isolates, whereas the combination of sed, sej, and ser was detected in 24% of clinical strains. S. aureus strains exhibited distinct combinations of SE genes, even if their pulsed-field gel electrophoresis and MLST patterns demonstrated clonality. USA300 strains also showed considerable variability in SE content, although they contained a lower number of SE genes (mean, 3). By contrast, SE content was unchanged in five pairs of serial isolates. SEB production by individual strains varied up to 200-fold, and even up to 15-fold in a pair of serial isolates. In conclusion, our results illustrate the genetic diversity of S. aureus strains with respect to enterotoxin genes and suggest that horizontal transfer of mobile genetic elements encoding virulence genes occurs frequently.