Vandenbroucke-Grauls, C.M.J.E.

Binary IS typing for staphylococcus aureus (Article)

2010-11-17T00:00:00Z

Background: We present an easily applicable test for rapid binary typing of Staphylococcus aureus: binary interspace (IS) typing. This test is a further development of a previously described molecular typing technique that is based on length polymorphisms of the 16S-23S rDNA interspace region of S. aureus. Methodology/Principal Findings: A novel approach of IS-typing was performed in which binary profiles are created. 424 human and animal derived MRSA and MSSA isolates were tested and a subset of these isolates was compared with multi locus sequence typing (MLST) and Amplified Fragment Length Polymorphism (AFLP). Binary IS typing had a high discriminatory potential and a good correlation with MLST and AFLP. Conclusions/Significance: Binary IS typing is easy to perform and binary profiles can be generated in a standardized fashion. These two features, combined with the high correlation with MLST clonal complexes, make the technique applicable for large-scale inter-laboratory molecular epidemiological comparisons.

Preventing Surgical-Site Infections in Nasal Carriers of Staphylococcus aureus (Article)

2010-01-07T00:00:00Z

Background Nasal carriers of Staphylococcus aureus are at increased risk for health care–associated infections with this organism. Decolonization of nasal and extranasal sites on hospital admission may reduce this risk. Methods In a randomized, double-blind, placebo-controlled, multicenter trial, we assessed whether rapid identification of S. aureus nasal carriers by means of a real-time polymerase-chain-reaction (PCR) assay, followed by treatment with mupirocin nasal ointment and chlorhexidine soap, reduces the risk of hospital-associated S. aureus infection. Results From October 2005 through June 2007, a total of 6771 patients were screened on admission. A total of 1270 nasal swabs from 1251 patients were positive for S. aureus. We enrolled 917 of these patients in the intention-to-treat analysis, of whom 808 (88.1%) underwent a surgical procedure. All the S. aureus strains identified on PCR assay were susceptible to methicillin and mupirocin. The rate of S. aureus infection was 3.4% (17 of 504 patients) in the mupirocin–chlorhexidine group, as compared with 7.7% (32 of 413 patients) in the placebo group (relative risk of infection, 0.42; 95% confidence interval [CI], 0.23 to 0.75). The effect of mupirocin–chlorhexidine treatment was most pronounced for deep surgical-site infections (relative risk, 0.21; 95% CI, 0.07 to 0.62). There was no significant difference in all-cause in-hospital mortality between the two groups. The time to the onset of nosocomial infection was shorter in the placebo group than in the mupirocin–chlorhexidine group (P=0.005). Conclusions The number of surgical-site S. aureus infections acquired in the hospital can be reduced by rapid screening and decolonizing of nasal carriers of S. aureus on admission. (Current Controlled Trials number, ISRCTN56186788 [controlled-trials.com] .)

Associations between Staphylococcus aureus Genotype, Infection, and In-Hospital Mortality: A Nested Case-Control Study (Article)

2005-09-01T00:00:00Z

We screened 14,008 adult nonsurgical patients for Staphylococcus aureus nasal carriage at hospital admission and assessed them for invasive S. aureus disease and in-hospital mortality. Multilocus sequence typing was performed on endogenous invasive strains and nasal strains of matched asymptomatic carriers to investigate whether virulent clones could be identified in nasal carriers. Clonal complex (CC) 45 was significantly underrepresented (odds ratio [OR], 0.16 [95% confidence interval {CI}, 0.04-0.59]) and CC30 was overrepresented (not statistically significant) among invasive strains (OR, 1.91 [95% CI, 0.91-4.0]). The distribution of CCs of invasive S. aureus strains in noncarriers did not differ from that in carriers. Those infected with S. aureus strains belonging to a CC had higher mortality than those infected with strains not belonging to a CC (P<.05), which indicates the coevolution of S. aureus virulence and spread in humans.

Risk and outcome of nosocomial Staphylococcus aureus bacteraemia in nasal carriers versus non-carriers (Article)

2004-08-21T00:00:00Z

Staphylococcus aureus is the second most frequent cause of nosocomial blood infections. We screened 14008 non-bacteraemic, non-surgical patients for S aureus nasal carriage at admission, and monitored them for development of bacteraemia. Nosocomial S aureus bacteraemia was three times more frequent in S aureus carriers (40/3420, 1.2%) than in non-carriers (41/10588, 0.4%; relative risk 3.0, 95% CI 2.0-4.7). However, in bacteraemic patients, all-cause mortality was significantly higher in non-carriers (19/41, 46%) than in carriers (seven/40, 18%, p=0.005). Additionally, S aureus bacteraemia-related death was significantly higher in non-carriers than in carriers (13/41 [32%] vs three/40 [8%], p=0.006). S aureus nasal carriers and non-carriers differ significantly in risk and outcome of nosocomial S aureus bacteraemia. Genotyping revealed that 80% of strains causing bacteraemia in carriers were endogenous

Mupirocin prophylaxis against nosocomial Staphylococcus aureus infections in nonsurgical patients: a randomized study (Article)

2004-01-01T00:00:00Z

BACKGROUND: Staphylococcus aureus nasal carriage is a major risk factor for nosocomial S. aureus infection. Studies show that intranasal mupirocin can prevent nosocomial surgical site infections. No data are available on the efficacy of mupirocin in nonsurgical patients. OBJECTIVE: To assess the efficacy of mupirocin prophylaxis in preventing nosocomial S. aureus infections in nonsurgical patients. DESIGN: Randomized, double-blind, placebo-controlled trial. SETTING: 3 tertiary care academic hospitals and 1 nonacademic hospital. PATIENTS: 1602 culture-proven S. aureus carriers hospitalized in nonsurgical departments. INTERVENTION: Therapy with mupirocin 2% nasal ointment (n = 793) or placebo ointment (n = 809), twice daily for 5 days, started 1 to 3 days after admission. MEASUREMENTS: Nosocomial S. aureus infections according to defined criteria, in-hospital mortality, duration of hospitalization, and time to nosocomial S. aureus infection. Staphylococcus aureus isolates were genotyped to assess whether infection was caused by endogenous strains. RESULTS: The mupirocin and placebo groups did not statistically differ in the rates of nosocomial S. aureus infections (mupirocin, 2.6%; placebo, 2.8%; risk difference, 0.2 percentage point [95% CI, -1.5 to 1.9 percentage points]), mortality (mupirocin, 3.0%; placebo, 2.8%; risk difference, -0.2 percentage point [CI, -1.9 to 1.5 percentage points]), or duration of hospitalization (median for both, 8 days). However, time to nosocomial S. aureus infection was decreased in the mupirocin group from 12 to 25 days (P > 0.2). A total of 77% of S. aureus nosocomial infections were endogenous. LIMITATIONS: A few infections in both groups may have been missed because investigators assessed a patient for infection only if microbiology culture results were positive for S. aureus. CONCLUSION: Routine culture for S. aureus nasal carriage at admission and subsequent mupirocin application does not provide effective prophylaxis against nosocomial S. aureus infections in nonsurgical patients.

Transcriptional phase variation of a type III restriction-modification system in Helicobacter pylori (Article)

2002-01-01T00:00:00Z

Phase variation is important in bacterial pathogenesis, since it generates antigenic variation for the evasion of immune responses and provides a strategy for quick adaptation to environmental changes. In this study, a Helicobacter pylori clone, designated MOD525, was identified that displayed phase-variable lacZ expression. The clone contained a transcriptional lacZ fusion in a putative type III DNA methyltransferase gene (mod, a homolog of the gene JHP1296 of strain J99), organized in an operon-like structure with a putative type III restriction endonuclease gene (res, a homolog of the gene JHP1297), located directly upstream of it. This putative type III restriction-modification system was common in H. pylori, as it was present in 15 out of 16 clinical isolates. Phase variation of the mod gene occurred at the transcriptional level both in clone MOD525 and in the parental H. pylori strain 1061. Further analysis showed that the res gene also displayed transcriptional phase variation and that it was cotranscribed with the mod gene. A homopolymeric cytosine tract (C tract) was present in the 5' coding region of the res gene. Length variation of this C tract caused the res open reading frame (ORF) to shift in and out of frame, switching the res gene on and off at the translational level. Surprisingly, the presence of an intact res ORF was positively correlated with active transcription of the downstream mod gene. Moreover, the C tract was required for the occurrence of transcriptional phase variation. Our finding that translation and transcription are linked during phase variation through slipped-strand mispairing is new for H. pylori.

Alterations in penicillin-binding protein 1A confer resistance to beta-lactam antibiotics in Helicobacter pylori (Article)

2002-01-01T00:00:00Z

Most Helicobacter pylori strains are susceptible to amoxicillin, an important component of combination therapies for H. pylori eradication. The isolation and initial characterization of the first reported stable amoxicillin-resistant clinical H. pylori isolate (the Hardenberg strain) have been published previously, but the underlying resistance mechanism was not described. Here we present evidence that the beta-lactam resistance of the Hardenberg strain results from a single amino acid substitution in HP0597, a penicillin-binding protein 1A (PBP1A) homolog of Escherichia coli. Replacement of the wild-type HP0597 (pbp1A) gene of the amoxicillin-sensitive (Amx(s)) H. pylori strain 1061 by the Hardenberg pbp1A gene resulted in a 100-fold increase in the MIC of amoxicillin. Sequence analysis of pbp1A of the Hardenberg strain, the Amx(s) H. pylori strain 1061, and four amoxicillin-resistant (Amx(r)) 1061 transformants revealed a few amino acid substitutions, of which only a single Ser(414)-->Arg substitution was involved in amoxicillin resistance. Although we cannot exclude that mutations in other genes are required for high-level amoxicillin resistance of the Hardenberg strain, this amino acid substitution in PBP1A resulted in an increased MIC of amoxicillin that was almost identical to that for the original Hardenberg strain.

Fecal carriage of vancomycin-resistant enterococci in hospitalized patients and those living in the community in The Netherlands (Article)

1997-01-01T00:00:00Z

In order to determine the prevalence of vancomycin-resistant enterococci (VRE) in The Netherlands, 624 hospitalized patients from intensive care units or hemato-oncology wards in nine hospitals and 200 patients living in the community were screened for VRE colonization. Enterococci were found in 49% of the hospitalized patients and in 80% of the patients living in the community. Of these strains, 43 and 32%, respectively, were Enterococcus faecium. VRE were isolated from 12 of 624 (2%) and 4 of 200 (2%) hospitalized patients and patients living in the community, respectively. PCR analysis of these 16 strains and 11 additional clinical VRE isolates from one of the participating hospitals revealed 24 vanA gene-containing, 1 vanB gene-containing, and 2 vanC1 gene-containing strains. All strains were cross-resistant to avoparcin but were sensitive to the novel glycopeptide antibiotic LY333328. Genotyping of the strains by arbitrarily primed PCR and pulsed-field gel electrophoresis revealed a high degree of genetic heterogeneity. This underscores a lack of hospital-driven endemicity of VRE clones. It is suggested that the VRE in hospitalized patients have originated from unknown sources in the community.

Nasal Carriage of Staphylococcus Aureus as a Major Risk Factor for Wound Infections after Cardiac Surgery (Article)

1995-01-01T00:00:00Z

Multicenter evaluation of arbitrarily primed PCR for typing of Staphylococcus aureus strains (Article)

1995-01-01T00:00:00Z

Fifty-nine isolates of Staphylococcus aureus and a single strain of Staphylococcus intermedius were typed by arbitrarily primed PCR (AP-PCR). To study reproducibility and discriminatory abilities, AP-PCR was carried out in seven laboratories with a standardized amplification protocol, template DNA isolated in a single institution, and a common set of three primers with different resolving powers. The 60 strains could be divided into 16 to 30 different genetic types, depending on the laboratory. This difference in resolution was due to differences in technical procedures (as shown by the deliberate introduction of experimental variables) and/or the interpretation of the DNA fingerprints. However, this did not hamper the epidemiologically correct clustering of related strains. The average number of different genotypes identified exceeded those of the more traditional typing strategies (F. C. Tenover, R. Arbeit, G. Archer, J. Biddle, S. Byrne, R. Goering, G. Hancock, G. A. Hebert, B. Hill, R. Hollis, W. R. Jarvis, B. Kreiswirth, W. Eisner, J. Maslow, L. K. McDougal, J. M. Miller, M. Mulligan, and M. A. Pfaller, J. Clin. Microbiol. 32:407-415, 1994). Comparison of AP-PCR with pulsed-field gel electrophoresis (PFGE) indicated the existence of strains with constant PFGE types but variable AP-PCR types. The reverse (constant AP-PCR and variable PFGE patterns) was also observed. This indicates additional resolution for combined analyses. It is concluded that AP-PCR is well suited for genetic analysis and monitoring of nosocomial spreading of staphylococci. The interlaboratory reproducibility of DNA-banding patterns and the intralaboratory standardization need improvement.

Long-term carriage, and transmission of methicillin-resistant Staphylococcus aureus after discharge from hospital (Article)

1992-11-01T00:00:00Z

The purpose of this study was to determine whether patients who become carriers of methicillin-resistant Staphylococcus aureus (MRSA) during their stay in hospital, remain colonized after discharge. Thirty-six patients colonized with MRSA during one of three outbreaks at Utrecht University Hospital (1986-89) were screened 2 or 3 years after they had become carriers. Patients were also interviewed to determine factors contributing to persistent carriage, such as antibiotics, re-admissions to the hospital, presence of skin lesions and chronic diseases. At the same time transmission of MRSA to family members was determined. The epidemic MRSA strain was still found in three patients (8%). One was a cystic fibrosis patient who had had frequent re-admissions to the hospital and had received several course of antibiotic treatment. Both of the other patients had skin lesions: a fistula and a colostomy respectively. None of the 44 family members of the patients was colonized or infected with MRSA. We conclude that long-term MRSA carriage occurs with low frequency and is comparable to persistent carriage of methicillin-sensitive Staphylococcus aureus (MSSA). Transmission of MRSA to healthy individuals in an antibiotic-free environment is a rare event.