Pertactin-Deficient Bordetella pertussis with Unusual Mechanism of Pertactin Disruption, Spain, 1986-2018.

Bordetella pertussis not expressing pertactin has increased in countries using acellular pertussis vaccines (ACV). The deficiency is mostly caused by pertactin gene disruption by IS481. To assess the effect of the transition from whole-cell vaccine to ACV on the emergence of B. pertussis not expressing pertactin in Spain, we studied 342 isolates collected during 1986-2018. We identified 93 pertactin-deficient isolates. All were detected after introduction of ACV and represented 38% of isolates collected during the ACV period; 58.1% belonged to a genetic cluster of isolates carrying the unusual prn::del(-292, 1340) mutation. Pertactin inactivation by IS481 insertion was identified in 23.7% of pertactin-deficient isolates, arising independently multiple times and in different phylogenetic branches. Our findings support the emergence and dissemination of a cluster of B. pertussis with an infrequent mechanism of pertactin disruption in Spain, probably resulting from introduction of ACV.

Clinical, epidemiological and microbiological characteristics of relapse and re-infection in Clostridium difficile infection.

Recurrent diarrhea is a common complication of Clostridium difficile infection (CDI). Recurrent CDI (r-CDI) may be produced by the persistence of spores (relapse) or by the acquisition of a new strain (reinfection). In this study, we analyze epidemiological, clinical, microbiological and laboratory data from patients with r-CDI, relapse, and reinfection-CDI over 5 years and compared with a control group (non r-CDI). Among 60 patients with r-CDI, 36 patients had stool samples collected from two or more episodes, which were molecularly analyzed. Based on ribotyping, 63.9% of the samples were relapse, and 36.1% reinfection. In a multivariable logistic regression analysis, previous antibiotic exposure was found to be a risk factor for r-CDI (OR: 2.23; 95% CI: 1.0-4.9; p = 0.04). Patients with relapse had previous antibiotic exposure more frequently than did patients with reinfection (p = 0.03), and patients with reinfection suffered more frequently from chronic liver disease (p = 0.02) than did relapse patients. Relapse patients compared with the control group had a higher percentage of previous antibiotic exposure, although the difference was statistically no significant (73.9% vs. 91.3 p = 0.06). No significant differences for the selected variables were observed between the reinfection and control groups, although we observed a higher percentage of patients with chronic liver disease (30.8% vs 13.3%; p = 0.08). All isolates were sensitive to metronidazole and vancomycin. No significant differences in antibiotic susceptibility were found between the different groups. Sporulation and germination frequency of r-CDI were higher than non r-CDI (p = 0.02 and p < 0.01, respectively). Nevertheless, there were statistically not significant differences between the relapse and reinfection groups. Both frequencies were compared between the first and second episode of CDI for the relapse and reinfection groups, but differences were not observed to be statistically significant. In conclusion, our study showed that the recurrence of CDI was associated with antibiotic use and sporulation/germination frequency, regardless of relapse or reinfection. The use of antibiotics would produce a dysbiosis and favor the persistence of the C. difficile spores and relapse. A possible alteration of the intestinal microbiota and the bile salts produced by chronic liver disease could favor reinfection.

Relationship between agr dysfunction and reduced vancomycin susceptibility in methicillin-susceptible Staphylococcus aureus causing bacteraemia.

OBJECTIVES: Limited data exist regarding the role of agr dysfunction in reducing susceptibility to vancomycin in methicillin-susceptible Staphylococcus aureus (MSSA). This study investigated the clinical and molecular epidemiology of MSSA causing bacteraemia, with emphasis on the reduced susceptibility to vancomycin (RSV) phenotype (MIC ≥ 1.5 mg/L) and its relationship with agr dysfunction. METHODS: All MSSA bloodstream isolates obtained at our hospital during 2010 were analysed. Antimicrobial susceptibility was determined and time-kill experiments were performed for oxacillin. Multilocus sequence type and agr genotype were determined and DNA microarray analysis of virulence factors was performed. agr dysfunction was assessed phenotypically and by RT-PCR quantification of RNAIII. RESULTS: Of 84 MSSA, 55 (65.5%) exhibited the RSV phenotype, comprising 13 clonal complexes. agr II polymorphism was more prevalent in RSV than non-RSV isolates (41.8% versus 17.2%, P = 0.023) and average levels of RNAIII gene expression were higher in RSV than non-RSV isolates (ΔCt 4.05 ± 3.29 versus 1.5 ± 2.11, P = 0.005), implying greater agr dysfunction in RSV MSSA. CONCLUSIONS: We demonstrated a correlation between RSV phenotype in MSSA and reduced agr expression, particularly in association with the agr II genotype. These results may help to understand the role of agr dysfunction in the increased mortality in MSSA infections.

Dalbavancin as sequential therapy in infective endocarditis: Real-life experience in elder and comorbid patients.

OBJECTIVES: This study aimed to evaluate the effectiveness of dalbavancin as sequential therapy in patients with infective endocarditis (IE) due to gram positive bacteria (GPB) in a real-life heterogenous cohort with comorbid patients. METHODS: A single center retrospective cohort study including all patients with definite IE treated with dalbavancin between January 2017 and February 2022 was developed. A 6-month follow-up was performed. The main outcomes were clinical cure rate, clinical and microbiological relapse, 6-month mortality, and adverse effects (AEs) rate. RESULTS: The study included 61 IE episodes. The median age was 78.5 years (interquartile range [IQR] 63.2-85.2), 78.7% were male, with a median Charlson comorbidity index of 7 (IQR 4-9) points. Overall, 49.2% suffered native valve IE. The most common microorganism was Staphylococcus aureus (26.3%) followed by Enterococcus faecalis (21.3%). The median duration of initial antimicrobial therapy and dalbavancin therapy were 27 (IQR 20-34) and 14 days (IQR 14-28) respectively. The total reduction of hospitalization was 1090 days. The most frequent dosage was 1500mg of dalbavancin every 14 days (96.7%). An AE was detected in 8.2% of patients, only one (1.6%) was attributed to dalbavancin (infusion reaction). Clinical cure was achieved in 86.9% of patients. One patient (1.6%) with Enterococcus faecalis IE suffered relapse. The 6-month mortality was 11.5%, with only one IE-related death (1.6%). CONCLUSION: This study shows a high efficacy of dalbavancin in a heterogeneous real-world cohort of IE patients, with an excellent safety profile. Dalbavancin allowed a substantial reduction of in-hospital length of stay.

Molecular characterization of Achromobacter isolates from cystic fibrosis and non-cystic fibrosis patients in Madrid, Spain.

Multilocus sequence typing and nrdA sequence analysis identified 6 different species or genogroups and 13 sequence types (STs) among 15 Achromobacter isolates from cystic fibrosis (CF) patients and 7 species or genogroups and 11 STs among 11 isolates from non-CF patients. Achromobacter xylosoxidans was the most frequently isolated species among CF patients.

Clonal diversity among Burkholderia cepacia complex isolates from cystic fibrosis patients in a reference unit.

INTRODUCTION: The epidemiology of Burkholderia cepacia complex (Bcc) in cystic fibrosis (CF) is not widely known. METHODS: All CF patients with Bcc between 2002 and 2011 were reviewed, and a molecular analysis of isolates was performed. RESULTS: The prevalence of Bcc infection was 7.2% (18/250). Molecular analysis of 16 Bcc isolates showed 5 species (7 B. contaminans, 6 B. cepacia, 1 B. cenocepacia, 1 B. multivorans, and 1 B. stabilis) and 13 sequence types. There were no cases of cross-transmission. CONCLUSION: A high diversity of Bcc species was found in infected CF patients.

VIM-2-producing multidrug-resistant Pseudomonas aeruginosa ST175 clone, Spain.

A total of 183 patients were colonized or infected with multidrug-resistant Pseudomonas aeruginosa isolates at a hospital in Spain during 2007-2010; prevalence increased over this period from 2.8% to 15.3%. To characterize these isolates, we performed molecular epidemiologic and drug resistance analysis. Genotyping showed that 104 (56.8%) isolates belonged to a single major clone (clone B), which was identified by multilocus sequence typing as sequence type (ST) 175. This clone was initially isolated from 5 patients in 2008, and then isolated from 23 patients in 2009 and 76 patients in 2010. PCR analysis of clone B isolates identified the bla(VIM-2) gene in all but 1 isolate, which harbored bla(IMP-22). ST175 isolates were susceptible to only amikacin (75%) and colistin (100%). Emergence of the ST175 clone represents a major health problem because it compromises therapy for treatment of P. aeruginosa nosocomial infections.

Sensitivity of Gram stain in the diagnosis of urethritis in men.

BACKGROUND: Acute urethritis is among the most common types of sexually transmitted diseases in men. The diagnosis usually requires microscopic evidence of urethritis, but sometimes urethral pathogens are detected in asymptomatic men without such evidence. The aims of this study were to assess the sensitivity of Gram stain in men with urethral symptoms and to relate it to the microorganisms isolated. METHODS: Between January 2006 and December 2007, 491 urethral samples were analysed. The authors assessed the presence of leukocytes by Gram stain and tested specifically for Chlamydia trachomatis, Ureaplasma urealyticum, Mycoplasma hominis and Trichomonas vaginalis, as well as analysing the results of conventional culture. RESULTS: The percentages of positive samples as a function of Gram category were two or less polymorphonuclear leukocytes (PMNLs)/high-power field (HPF) 25% (92/364), three to four PMNLs/HPF 32% (18/57) and five or more PMNLs/HPF 54% (38/70). Classing samples with more than two PMNLs/HPF as positive, the sensitivity, specificity and positive likelihood ratio for Gram stain were 38% (95% CI 30 to 46), 79% (95% CI 75 to 84) and 1.8 (95% CI 1.4 to 2.4), respectively. On the other hand, taking as positive five or more PMNLs/HPF, the sensitivity, specificity and positive likelihood ratio for Gram stain were 26% (95% CI 18 to 33), 91% (95% CI 87 to 94) and 2.7 (95% CI 1.8 to 4.2), respectively. The sensitivity of Gram stain to Neisseria gonorrhoeae, Chlamydia trachomatis and Ureaplasma urealyticum were 80% (95% CI 64 to 96), 23% (95% CI 8 to 39) and 11% (95% CI 2 to 20), respectively. CONCLUSION: The low sensitivity of Gram stain means that negative results do not exclude the presence of urethritis in symptomatic patients.

Clinical and molecular characteristics of infections with CO2-dependent small-colony variants of Staphylococcus aureus.

Most Staphylococcus aureus small-colony variants (SCVs) are auxotrophs for menadione, hemin, or thymidine but rarely for CO(2). We conducted a prospective investigation of all clinical cases of CO(2)-dependent S. aureus during a 3-year period. We found 14 CO(2)-dependent isolates of S. aureus from 14 patients that fulfilled all requirements to be considered SCVs, 9 of which were methicillin resistant. The clinical presentations included four cases of catheter-related bacteremia, one complicated by endocarditis; two deep infections (mediastinitis and spondylodiscitis); four wound infections; two respiratory infections; and two cases of nasal colonization. Pulsed-field gel electrophoresis typing showed that the 14 isolates were distributed into 4 types corresponding to sequence types ST125-agr group II (agrII), ST30-agrIII, ST34-agrIII, and ST45-agrI. An array hybridization technique performed on the 14 CO(2)-dependent isolates and 20 S. aureus isolates with normal phenotype and representing the same sequence types showed that all possessed the enterotoxin gene cluster egc, as well as the genes for alpha-hemolysin and delta-hemolysin; biofilm genes icaA, icaC, and icaD; several microbial surface components recognizing adhesive matrix molecules (MSCRAMM) genes (clfA, clfB, ebh, eno, fib, ebpS, sdrC, and vw); and the isaB gene. Our study confirms the importance of CO(2)-dependent SCVs of S. aureus as significant pathogens. Clinical microbiologists should be aware of this kind of auxotrophy because recovery and identification are challenging and not routine. Further studies are necessary to determine the incidence of CO(2) auxotrophs of S. aureus, the factors that select these strains in the host, and the genetic basis of this type of auxotrophy.

Improved blood culture workflow in the time to detection of microorganisms placing incubators systems outside of microbiology laboratory.

PURPOSE: We analyzed the workflow of the blood culture procedure with one blood culture incubator in the microbiology laboratory, in comparison with the workflow with the incubators systems placing outside, and in a microbiology laboratory without 24-h staffing. METHODS: We assessed the elapsed time (ET) and time-to-result (TTR) in the two laboratory workflows during 1 month period in consecutive years. First period with one BACT/ALERT 3D module located in the microbiology laboratory (ML) (access 8 a.m. to 10 p.m.) and second period with three BACT/ALERT VIRTUO modules (one located in ML and two in the core sample laboratory, access 24 h). RESULTS: The mean ET with BACT/ALERT 3D was 7.09 ± 6.15 h and 1.32 ± 3.14 h with BACT/ALERT VIRTUO. During the 8:00 a.m. to 10:00 p.m. shift, the average ETs were 3.54 ± 5.06 vs 1.59 ± 1.29 h for the two time periods, respectively. Since the automated loading of bottles on the BACT/ALERT VIRTUO allows processing of blood cultures during the night shift, there was a significant reduction of time during the 10:00 p.m. to 8:00 a.m. shift, where the average ET was 10.52 ± 5.23 vs 1.00 ± 4.40 h, respectively. The percentage of positivity in the first period was 9.03% and 11.18% in the second (p = 0.0003). The average TTR in the first period was 24.78 ± 15.9 h and 16.85 ± 14.13 h in the second (p < 0.0001). CONCLUSIONS: Easy 24-h access to blood culture incubators resulted in significant improvement in the workflow of blood culture, decreasing ET, and therefore decreasing the time to positivity and the efficiency of recovery.

Rapid identification of bacteria directly from positive blood cultures by a modified method using a serum separator tube and matrix-assisted laser desorption ionization - time of flight MS.

Introduction. Several studies have used matrix-assisted laser desorption ionization-time of flight MS (MALDI-TOF) with a serum separator tube (SST) to perform rapid identification of microorganisms directly from positive blood cultures (BCs), with different performances and methodologies.Hypothesis / Gap Statement. The use of TSS could significantly reduce the time of identification of microorganisms that produce bacteremia.Aim. Our goals were to evaluate bacterial identification by MALDI-TOF using a method based on an SST and compare it with MALDI-TOF after subculture for 18-24 h.Methodology. BCs no more than 1 h after a positive growth signal were included in the study. Analysis of results was expressed as a score. Information about time to a positive signal and number of microorganisms was collected.Results. In total, 253 BCs were analysed; 45.5 % gave a reliable result, 23.3 % an unreliable result and 31.2 % an error in identification. In gram-negative and gram-positive bacteria, the percentages of reliable results were 83.5 and 21.8 %, respectively. According to time to positive signal, the percentages of correct identification and mean score were 81.1 % (99/122) and 1.89±0.30 in Group 1 (<15 h); and 57.2 % (75/131) and 1.70±0.32 in Group 2 (>15 h), respectively (P <0.001). According to the number of microorganisms, the corresponding percentages of correct identification and mean scores were: Group 1 [≤50 microorganisms observed per field (MOF)], 50/94 (53.19 %) and 1.72±0.32; Group 2 (51-100 MOF): 44/66 (66.67 %) and 1.85±0.34; Group 3 (>100 MOF): 79/93 (84.94 %) and 1.84±0.31.Conclusion. This method allowed us to obtain a high percentage of the aetiological agent of bacteraemia in less than 30 min after a positive BC.

Shigella sonnei bacteraemia in a cystic fibrosis patient: case report and literature review.

>INTRODUCTION: Shigellosis has a gastrointestinal presentation of variable severity in which bacteraemia is uncommon. We describe the first reported case of Shigella sonnei bacteraemia and intestinal coinfection with Clostridioides difficile in a cystic fibrosis patient. The literature on S. sonnei bacteraemia in adult and paediatric populations is also reviewed. CASE PRESENTATION: A 29-year-old male with cystic fibrosis presented with profuse acute watery diarrhoea, abdominal pain, shivering and fever. The patient showed mixed cardiogenic and septic shock. Despite antibiotic therapy, volume replacement therapy and vasoactive drugs, the patient showed biventricular dysfunction and multiple organ failure requiring implantation of an intra-aortic balloon pump (IABP) with extracorporeal membrane oxygenation (ECMO). C. difficile and S. sonnei were detected in the stools. Escherichia coli was identified in the blood by matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry, although after re-evaluation with biochemical and antiserum agglutination tests, the isolate was confirmed as S. sonnei. After adjustment of the antibiotic therapy to vancomycin, meropenem, amikacin and metronidazole and continuing with ECMO and IABP support for 8 days, the patient improved and was finally discharged after 44 days. CONCLUSION: S. sonnei bacteraemia is an unusual entity that should be kept in mind because of the severity of its presentation and high mortality. In acute gastroenteritis and fever, especially in paediatric patients under 5 years old and adults with criteria for immunosuppression or chronic diseases, blood and stool cultures provide simple information that is nonetheless very important for the management and prognosis of these patients.

Evaluation of the multiplex PCR Allplex-GI assay in the detection of bacterial pathogens in diarrheic stool samples.

Rapid and accurate detection of the pathogens that cause gastrointestinal infection is important for appropriate therapy and proper infection control. This study assesses the performance of a new molecular assay for simultaneous detection of 13 different gastrointestinal bacteria in stool specimens. Using the Allplex GI-Bacteria (AGI-BI/AGI-BII) assay, a total of 394 stool samples were tested and the results were compared with culturing on selective differential followed by identification by mass spectroscopy. Discordant results were analyzed by a different multiplex PCR method, the Fast-Track Diagnostics Bacterial gastroenteritis (FTD-BG). The routine method (RM) detected 109 (27.7%) positive samples and the Allplex-GI assay, 261 (66.2%). Analysis of discordant results revealed that the molecular assay detected 44 pathogens that were not detected by the RM, including 23 Campylobacter spp., 11 Salmonella spp, 3 Y. enterocolitica, 2 EIEC/Shigella spp, 2 E. coli 0157, 2 C. difficile and 1 Aeromonas spp. Five cases not detected by the molecular method were detected by the RM (3 Aeromonas spp, 1 Salmonella spp and 1 Y. enterocolitica). For all targets, the percentages of sensitivity and specificity were >95%, except for Aeromonas spp., which were 81% and 99% respectively. This study suggests that Allplex-GI multiplex PCR is a sensitive and specific assay that enables a rapid and accurate diagnosis of bacterial gastrointestinal infections.

Molecular epidemiology of carbapenemase-producing Klebsiella pneumoniae in a hospital in Madrid: Successful establishment of an OXA-48 ST11 clone.

Here we report a retrospective clinical and molecular study conducted in a tertiary care facility in southern Madrid, Spain, from January 2009 to February 2014 to investigate the epidemiology of carbapenemase-producing Klebsiella pneumoniae (CPKp). Carbapenemase genes were identified in 97 non-duplicate K. pneumoniae isolates, including 59 harbouring blaOXA-48, 37 harbouring blaVIM-1 and 1 harbouring blaKPC-2. Pulsed-field gel electrophoresis (PFGE) analysis verified the presence of 20 different clonal types, whilst multilocus sequence typing (MLST) assigned the isolates to eight sequence types (STs). A gradual increase was noted in the number of CPKp isolated, ranging from 0.8% in 2009 to 4.3% in 2013. A large outbreak was also identified, initiated in 2013 owing to a blaOXA-48 and blaCTX-M-15 co-producing ST11 clone and involving a total of 44 patients. Whole-genome sequencing was used to characterise the resistome of a representative isolate from this outbreak. Bioinformatics analysis revealed the presence of 121 genes related to antibiotic and antiseptic resistance, mutations in the ompk35 and ompk36 genes, and the presence of the blaOXA-48 gene on a 62 811bp IncL/M-type plasmid as part of a Tn1999.2 composite transposon. These results portray the increasing trend in carbapenemase-producing isolates in this hospital and highlight the successful establishment of a blaOXA-48 and blaCTX-M-15 co-producing ST11 clone that has led to the displacement of previous circulating clones.

[Evaluation of the results obtained by the Coagucheck S coagulometer in the control of the oral anticoagulant treatment]. / Valoración de los resultados obtenidos con el coagulómetro Coagucheck S en el control del tratamiento con anticoagulantes orales.

BACKGROUND AND OBJECTIVE: Our purpose was to evaluate the control of oral anticoagulant treatment (OAT) in capillary blood by the Coagucheck S System. PATIENTS AND METHOD: Descriptive cross-sectional study. 155 patients under treatment with oral anticoagulants were studied. The INR was determined in venous blood by the CA-6000 System (DADE-Behring Laboratories) and capillary blood was determined by the Coagulocheck S System (Roche Laboratories). RESULTS: Mean and standard deviation were: 2.64 (1.25) for the CA6000 System and 2.95 (1.58) for the Coagucheck S System. Pearson's correlation coefficient was r = 0.912. Intraclass correlation index was 0.86 (0.79-0.91) and the mean difference was 0.309 (0.202-0.417). The therapeutic attitude was the same in 80%. CONCLUSION: Both systems are interchangeable with regard to the INR measurement aimed at the control of oral anticoagulant therapy

Multiclonal spread of VIM-1-producing Enterobacter cloacae isolates associated with In624 and In488 integrons located in an IncHI2 plasmid.

Over a 6-year period (2007-2012), the emergence of Enterobacter cloacae isolates resistant to ß-lactams and with reduced susceptibility to carbapenems was observed in Hospital Universitario 12 de Octubre (Madrid, Spain). To determine the possible role of metallo-ß-lactamases (MBLs) in the resistance profile of these isolates, a molecular and clinical epidemiological study was performed, including determination of patients' clinical characteristics, genetic diversity of strains, resistance mechanisms to carbapenems, and the genetic environment of VIM-1. A total of 73 E. cloacae isolates showed resistance to extended-spectrum cephalosporins and reduced susceptibility to at least one carbapenem during 2007-2012. PCR amplification revealed the presence of bla(VIM-1) gene in 37 isolates, bla(VIM-2) in 1 isolate and bla(KPC) in 5 isolates. Molecular typing showed high clonal diversity of E. cloacae isolates carrying bla(VIM-1). The genetic environment of bla(VIM-1) was investigated and two integron structures were found: intI-bla(VIM-1)-aacA4-dfrB1-aadA1-catB2-qacEΔ1/sul1 (In624); and intI-bla(VIM-1)-aacA4-aadA1-qacEΔ1/sul1 (In488). Isolates belonging to three clones (A, F and G) harboured different types of integron (In624 or In488) despite belonging to the same clone. Conjugal experiments showed an association with a conjugative plasmid of ca. 300 kb belonging to IncHI2 group, which is common in Spanish hospitals, suggesting that the widespread dissemination of bla(VIM-1) may be due to horizontal transfer of mobile genetic determinants rather than the result of spreading of a few clones. These results have implications for infection control programmes in the hospital.

Usefulness of endoluminal catheter colonization surveillance cultures to reduce catheter-related bloodstream infections in hemodialysis.

BACKGROUND: To evaluate the use of surveillance cultures (SCs) to prevent catheter-related bloodstream infections (CRBSIs) in asymptomatic hemodialysis (HD) patients. METHODS: In 2011-2012, we conducted a prospective study of HD patients with tunneled cuffed central venous catheters (TCCs). Colonization of the catheter lumen was assessed every 15 days by inoculating ~5 mL endoluminal blood into aerobic culture bottles. Individual patients were triaged based on SC results: group 1 (negative); group 2 (coagulase-negative Staphylococcus [CoNS] with time-to-positivity (TTP) >14 hours); group 3 (CoNS with TTP ≤14 hours); and group 4 (any microorganism other than CoNS and any TTP). RESULTS: We studied 104 patients (129 TCCs). Median follow-up was 262.5 days (interquartile range [IR], 135.0-365.0). A total of 1,734 SCs were collected (median, 18 per patient; IR, 10.0-24.0), of which 1,634 (94.2%) were negative (group 1) and 100 (5.8%) were positive (group 2: 79; group 3: 12, group 4: 9). In groups 2 and 3, 19 TCCs required antibiotic lock therapy (ALT). In group 4, all patients received intravenous therapy and ALT. Under this protocol, there were 0.27 episodes of CRBSI per 1,000 catheter days compared with 1.65 (P < .001) prior to its implementation. CONCLUSION: SCs based on easily accessible samples proved useful in triaging HD patients at a high risk of infection.

Staphylococcus aureus abscesses: methicillin-resistance or Panton-Valentine leukocidin presence?

INTRODUCTION: Panton-Valentine leukocidin (PVL) is a toxin associated with community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA) worldwide and also occurs in community-associated methicillin-susceptible S aureus (CA-MSSA) strains. The aims of the study were to determine the prevalence of PVL in community-onset S aureus skin and soft-tissue infections (SSTIs) and to analyse the influence of methicillin resistance and PVL presence on the clinical characteristics of these infections. PATIENTS AND METHODS: We prospectively enrolled all children with S aureus community-onset SSTIs attending the emergency department of a tertiary hospital between 2007 and 2009. Results A total of 142 S aureus SSTIs were identified, 46 (32%) were PVL positive. The proportion of subjects in each group was: 89 (63%) PVL-MSSA, 33 (23%) PVL+MSSA, 13 (9%) PVL+MRSA and 7 (5%) PVL-MRSA. PVL+infections were more frequently abscesses (63% vs 39%, p<0.01), and more often required incision and drainage (p<0.01) and hospital admission (46% vs 26%, p=0.02). MRSA infections were also more frequently associated with abscesses but in a multivariable analysis only PVL remained independently related (OR 2.33; 95% CI 1.10 to 4.90). CONCLUSIONS: Our study found a high prevalence of PVL presence in community-onset S aureus SSTIs in children in Spain. This toxin is associated with more abscess formation, regardless of methicillin resistance.