Outbreaks of methicillin-resistant Staphylococcus aureus among staff and dogs in Swedish small animal hospitals.

Methicillin-resistant Staphylococcus aureus (MRSA) was found in a dog for the first time in Sweden in 2006. Between October 2006 and May 2007, MRSA was diagnosed in 7 more dogs that had been treated in 3 different small animal hospitals, located 150-200 km apart, in different counties of Sweden. Screening of the animal hospital staff and environment in these small animal hospitals showed 20 of 152 staff to be positive for MRSA, with rates between 2% and 18% in the different hospitals, while all 128 environmental samples were negative. All MRSA isolates from dogs and staff belonged to spa type t032, were Panton-Valentine leukocidin (PVL)-negative, and had indistinguishable pulsed-field gel electrophoresis patterns, except for 2 isolates with closely related patterns. To our knowledge, this is the first report of multiple outbreaks of MRSA in dogs caused by the same strain within a short time frame, and appearing in a country with low prevalence of MRSA in both humans and dogs. This highlights the importance of infection control programs in animal hospitals and in animal health care. Awareness of MRSA as an occupational risk for veterinary personnel is essential.

Occurrence of potentially pathogenic bacteria on the hands of hospital patients before and after the introduction of patient hand disinfection.

The leading cause of nosocomial infections and spread of multiresistant bacteria is considered to be the failure of healthcare workers to perform appropriate hand hygiene. The role of the hands of hospital patients in the spread of infection has received little attention. The aim of the present study was to investigate the occurrence of potentially pathogenic bacteria on the patients' hands. Quantitative cultures were repeatedly taken from the fingertips of patients at a rehabilitation clinic before and after an intervention in which patient hand disinfection was introduced and promoted. Before the intervention, the occurrence on the hands of Escherichia coli, Klebsiella spp., enterococci, Staphylococcus aureus and yeast was a common finding. The colony counts of S. aureus were often higher than the counts of other organisms. After the intervention, the level of hand contamination was lower. The difference was statistically significant (p < 0.05) concerning Enterobacteriaceae, both when the patients were resting and at lunch time, for enterococci and total bacterial counts at lunch time, and for yeast when they were resting. Concerning S. aureus, the difference was not statistically significant, neither while resting nor at lunch time. The role of the patients in the spread of pathogenic bacteria merits more discussion.

Prevalence of qnr determinants among extended-spectrum beta-lactamase-positive Enterobacteriaceae clinical isolates in southern Stockholm, Sweden.

Three hundred and nineteen extended-spectrum beta-lactamase-positive Enterobacteriaceae clinical isolates were screened for qnr genes. Twelve isolates were positive for qnr, including one qnrA1, two qnrB1, three qnrB2, one qnrB4, one qnrB6 and four qnrS1. No qnr-positive strains were identified among the isolates recovered before 2006. The first qnr-positive Escherichia coli was detected from a patient in 2006. qnr genes remained rare in E. coli (6/288; 2.1%), but appeared to be more prevalent in Klebsiella pneumoniae (4/25; 16%) and Enterobacter cloacae (2/3; 66.7%). All qnr-positive isolates were resistant to nalidixic acid while presenting varied susceptibilities to fluoroquinolones. Isolates harbouring qnrB4 or qnrB6 were highly resistant to all the fluoroquinolones tested. Their high-level resistance is associated with multiple chromosomal substitutions in gyrA and parC. Alterations at codons Ser-83 and Asp-87 in GyrA and at codons Ser-80 and Glu-84 in ParC were observed in these isolates.

Molecular epidemiology of extended-spectrum beta-lactamases among Escherichia coli isolates collected in a Swedish hospital and its associated health care facilities from 2001 to 2006.

The genetic characteristics and molecular epidemiology of extended-spectrum beta-lactamases (ESBLs) among Escherichia coli isolates were investigated at a general hospital and its associated health care facilities in Stockholm, Sweden, during the period from 2001 to 2006. Of 87 consecutive nonduplicate ESBL-positive isolates, 80 isolates encoded CTX-M-type ESBLs, 64 of which were group 1 enzymes. TEM-type and OXA-type beta-lactamases were encoded in 63 and 59% of the ESBL isolates, respectively. Pulsed-field gel electrophoresis (PFGE) analysis revealed 40 different pulsotypes, consisting of 11 clones accounting for 66% of all isolates, and 29 unique patterns. Moreover, of the 11 clones, clones 1 and 4 comprised half of the clonally related isolates (28 of 57). Clone 1 was a persistent endemic clone in the area throughout the years, and clone 4 emerged in 2003. However, in recent years, clone 1 isolates were no longer predominant and were gradually replaced by new emerging strains. Concerning beta-lactamase gene profiles in relation to PFGE pulsotypes, clone-related bla profiles were observed in certain clones, while in most cases different bla profiles could be observed in the same clone, and the same bla profile could be present in different clones. The molecular epidemiology of ESBL-positive E. coli in the area shows shifts in predominant strains and increased clonal diversity over time. The study also indicated that both clonal spread of epidemic strains and transfer of transposable genetic elements might contribute to the proliferation of ESBLs.

Epidemiology of methicillin-resistant Staphylococcus aureus in Southern Stockholm, 2000-2003.

The number of patients infected/colonised by methicillin-resistant Staphylococcus aureus (MRSA) began to rise in southern Stockholm in 2000. The present study is an analysis based on information concerning the 181 newly detected patients with MRSA during 2000-2003, results of antibiotic susceptibility tests, molecular epidemiologic typing with pulsed-field gel electrophoresis and multilocus sequence typing, and detection of Panton-Valentine leukocidin genes. No single MRSA clone was causing the epidemic situation. Instead a number of rather small, limited outbreaks took place, caused by different MRSA clones and often starting from a patient who had acquired MRSA abroad. Different clones were found in the hospitals and in the community. Sequence types (STs) 22, 239, 247, 8, and 45 were the predominant clones causing outbreaks among hospitalized patients. Most isolates belonging to these clones were multiply resistant to antimicrobial agents. Suspected glycopeptide heteroresistance was found in isolates belonging to STs 247, 239, and 592. In the community, the most widely spread MRSA was ST 80, although isolates belonging to STs 8, 30, 59, and 150 were also observed. The community-acquired isolates were usually not multiresistant. In contrast to the clones transmitted in hospitals, most community-acquired MRSA clones harbored the PVL genes, except for isolates belonging to ST 150 spread in the community among homeless people with foot ulcers and wounds.

ICU stay promotes enrichment and dissemination of multiresistant coagulase-negative staphylococcal strains.

Patients in the intensive care unit (ICU) are prone to be colonized and infected by multi-resistant bacteria. It is previously known that nosocomial infections are often preceded by cross-transmission events. The aim of the present investigation was to study the impact of the patient's length of ICU stay on the resistance patterns, diversity and dissemination of coagulase-negative staphylococci (CoNS) within and between patients. Two groups of patients were studied, including 20 consecutive patients sampled within 2 h from admission (short-stayers, SS), and all patients treated for at least 5 d in the ICU (long-stayers, LS), available for sampling every second week (n = 15). Sampling was performed from 5 sites: oropharynx, nares, neck, axilla and perineum. A total of 868 CoNS isolates deriving from LS patients and 403 isolates from SS patients were analysed for antimicrobial susceptibility, clonal diversity and dissemination within and between patients. The highest resistance rates were seen for oxacillin and ciprofloxacin, being 92% and 83%, respectively. Long-stayers were at significantly higher risk of being colonized with CoNS isolates resistant against oxacillin, clindamycin, ciprofloxacin, gentamicin as well as with multiresistant strains. By genotyping 22 phenotypes that were shared among at least 2 patients, 32 PFGE types of which 16 colonized more than 1 individual were identified. One of the clones was isolated from 10 individuals, including 2 SS patients, indicating an epidemic strain. Prolonged ICU stay was significantly correlated to decreased clonal diversity, increased endogenous dissemination of resistant strains and cross-transmission. The results emphasize the importance of good infection control practice, especially in this vulnerable group of patients.

Use of cefoxitin-based selective broth for improved detection of methicillin-resistant Staphylococcus aureus.

A cefoxitin-based selective broth was evaluated for its efficiency in detecting methicillin-resistant Staphylococcus aureus (MRSA) by the use of laboratory reference strains, clinical isolates of different clones, and clinical samples. The cefoxitin-based broth was proved to be more sensitive and rapid for the detection of MRSA strains, especially heterogeneously resistant strains, than the oxacillin-based broth.

Evaluation of two new chromogenic media, CHROMagar MRSA and S. aureus ID, for identifying Staphylococcus aureus and screening methicillin-resistant S. aureus.

Thirty-nine methicillin-resistant Staphylococcus aureus (MRSA) isolates with diverse genetic backgrounds and two reference strains were correctly identified as S. aureus on CHROMagar MRSA and S. aureus ID media. Growth inhibition on CHROMagar MRSA was noted. A combination of cefoxitin disk and S. aureus ID was found suitable for rapid MRSA screening.

Molecular epidemiological analysis of Escherichia coli isolates producing extended-spectrum beta-lactamases for identification of nosocomial outbreaks in Stockholm, Sweden.

From June to October of 2002, a cluster of Escherichia coli isolates producing extended-spectrum beta-lactamases (ESBLs) was detected in Stockholm. The isolates were grouped into two clones, one of which had already circulated in the same area before the outbreak. CTX-M-type ESBLs and coresistance to ciprofloxacin were identified in the strains.

A prospective epidemiological survey of candidaemia in Sweden.

A prospective epidemiological survey of candidaemia was performed in central Sweden from January 1998 to December 1999. In total, 191 episodes were reported with an overall rate of 0.32/1000 admissions. Candida albicans was identified in 128 cases (67%), followed by Candida glabrata in 30 (15.7%) and Candida parapsilosis in 14 (7.3%). Predisposing factors included surgery (31.4%), intensive care (18.8%), solid tumour or haematological malignancy (15.7%), and foetal immaturity (15.7%). Non-albicans Candida species were more prevalent among patients with haematological malignancies (56%), compared to surgical (30%) and ICU patients (19%). The crude mortality rate of candidaemia was 31%. The highest mortality rate was observed in patients with haematological malignancies (41.2%), age > 70 y (41%), surgery (38.5%) and infections with > 1 Candida species (40%) or C. glabrata (38%).

Rapid screening and identification of methicillin-resistant Staphylococcus aureus from clinical samples by selective-broth and real-time PCR assay.

A screening method for methicillin-resistant Staphylococcus aureus (MRSA) by using selective broth and real-time PCR (broth-PCR) was developed and evaluated. The samples (n = 304) were cultured in the broth overnight, followed by nuc gene detection by real-time PCR. nuc-negative samples were further checked for the presence of nuc amplification inhibitors by a PCR internal inhibitor assay. nuc-positive samples and nuc-negative samples with PCR inhibitors were cultured onto plates and processed further. The diagnostic values for this MRSA screening method were 93.3% sensitivity, 89.6% specificity, 31.8% positive predictive value, and 99.6% negative predictive value. The application of the broth-PCR method will be able to report most of the negative samples (258 of 289 [89.3%]) on the next morning and can save as much as 84.9% (258 of 304) of the labor and cost spent on processing the nuc-negative specimens on plates. In the study, all the samples were processed in parallel by the broth enrichment method and the plating method for comparison. To identify MRSA, the isolated oxacillin-resistant S. aureus strains were tested by a duplex real-time PCR targeting the mecA gene and the nuc gene. A collection of MRSA, methicillin-susceptible Staphylococcus aureus, methicillin-resistant Staphylococcus epidermidis, and methicillin-susceptible Staphylococcus epidermidis strains and a panel of standard strains of 11 bacterial species other than S. aureus were also tested by this method, which was proved to be a valuable tool for MRSA identification in a routine microbiological laboratory.

A lack of serologic evidence of transmission of Chlamydia pneumoniae by transfusion of buffy coat-depleted RBCs.

BACKGROUND: Recent studies have shown that a high percentage of blood donors harbor Chlamydia pneumoniae DNA and antigens within their PBMNCs. The aim of the present study was to investigate whether recipients of RBC transfusions who were seronegative for C. pneumoniae before transfusion showed any evidence of seroconversion after transfusion. STUDY DESIGN AND METHODS: Patients who were possible recipients of RBC transfusion and negative in a screen test for IgG antibodies against C. pneumoniae at the time of blood group determination were candidates to be included in the study. The patients were contacted 3.0 to 3.5 months after the blood group determination, and those who accepted to participate agreed that another venous blood sample could be taken. RESULTS: Among the patients who participated, 53 had become recipients of RBC transfusion (transfused group), and 51 later did not receive any RBC transfusion (control group). No significant change was found in IgG titer against C. pneumoniae between the first and the second sample from the same patient, in either the transfused group or the control group. CONCLUSION: In our study, which was limited to 53 seronegative recipients of RBC units from seropositive donors, we found no serologic evidence that C. pneumoniae could be transmitted by RBC transfusion.