Emergence of extended-spectrum beta-lactamase-producing Escherichia coli and Klebsiella pneumoniae during the years 2000 and 2004 in Helsinki, Finland.

The molecular epidemiology of 33 Escherichia coli and 81 Klebsiella pneumoniae extended-spectrum beta-lactamase-producing healthcare-associated and community-acquired isolates collected in the Helsinki district during 2000-2004 was investigated. Clonality studies, antimicrobial susceptibility and genotyping of the isolates were performed. Newly emerging CTX-M-producing E. coli and bla(SHV-12)-producing K. pneumoniae isolates were detected. Clonal clusters of both species persisted throughout the study period.

Factors predisposing to acute and recurrent bacterial non-necrotizing cellulitis in hospitalized patients: a prospective case-control study.

Acute non-necrotizing cellulitis is a skin infection with a tendency to recur. Both general and local risk factors for erysipelas or cellulitis have been recognized in previous studies using hospitalized controls. The aim of this study was to identify risk factors for cellulitis using controls recruited from the general population. We also compared patients with a history of previous cellulitis with those suffering a single episode, with regard to the risk factors: length of stay in hospital, duration of fever, and inflammatory response as measured by C-reactive protein (CRP) level and leukocyte count. Ninety hospitalized cellulitis patients and 90 population controls matched for age and sex were interviewed and clinically examined during the period April 2004 to March 2005. In multivariate analysis, chronic oedema of the extremity, disruption of the cutaneous barrier and obesity were independently associated with acute cellulitis. Forty-four (49%) patients had a positive history (PH) of at least one cellulitis episode before entering the study. Obesity and previous ipsilateral surgical procedure were statistically significantly more common in PH patients, whereas a recent (<1 month) traumatic wound was more common in patients with a negative history (NH) of cellulitis. PH patients had longer duration of fever and hospital stay, and their CRP and leukocyte values more often peaked at a high level than those of NH patients. Oedema, broken skin and obesity are risk factors for acute cellulitis. The inflammatory response as indicated by CRP level and leukocyte count is statistically significantly more severe in PH than NH patients.

Evaluation of a commercial MRSA assay when multiple MRSA strains are causing epidemics.

Rapid and reliable diagnostic methods are needed to control methicillin-resistant Staphylococcus aureus (MRSA) transmission. We studied the BD GeneOhm MRSA Assay which is based on one specific amplification product at the junction of the right extremity sequence of the staphylococcal cassette chromosome mec (SCCmec) and the chromosomal sequence of orfX of S. aureus. The test was applied on 95 clinical isolates in Finland: 83% were positive. The isolates giving negative results represented several pulsed-field gel electrophoresis (PFGE) types and harboured SCCmec types IV, V, VI or were new types with different combinations of ccr genes.

Clinical presentations and epidemiology of beta-haemolytic streptococcal bacteraemia: a population-based study.

In this population-based study, all 314 episodes of beta-haemolytic streptococcal bacteraemia in adult patients in the Pirkanmaa area, Finland, during the 10-year period 1995-2004 were retrospectively reviewed. Altogether, 92 cases of bacteraemia caused by Lancefield group A beta-haemolytic streptococci (GAS), 76 caused by group B beta-haemolytic streptococci (GBS), 18 caused by group C beta-haemolytic streptococci (GCS) and 128 caused by group G beta-haemolytic streptococci (GGS) were identified. The most important finding was that the incidence of GGS increased during the study period. Disruption of the cutaneous barrier was a very common predisposing factor in GAS and GGS bacteraemias. Skin infections were the presenting clinical manifestations in two-thirds of GAS and GGS bacteraemias.

Epidemic of severe Streptococcus pyogenes infections in injecting drug users in the UK, 2003-2004.

During the late 1990s, increases in referrals to the national reference laboratory of Streptococcus pyogenes isolates from injecting drug users (IDUs) with severe soft tissue infection indicated an emerging problem in the UK, later confirmed during the 2003-2004 European enhanced surveillance (Strep-EURO) programme. In light of these findings, further analyses were undertaken in an attempt to understand the reasons behind this increase in referrals. Single and multivariable analyses were undertaken to compare clinical, microbiological and demographic characteristics of IDUs diagnosed with severe S. pyogenes infection during the 2003-2004 enhanced surveillance study with those of other cases arising during this same period. Temporal and spatial analyses were undertaken for IDUs to identify clustering, as a means of understanding the transmission dynamics underpinning this increase. Infections in IDUs were spread across the UK, with some concentration in northern England and London. IDUs presented with a wide range of clinical manifestations, including pneumonia, which was found to be significantly more common in IDUs (OR 3.00) than in other cases. Marked differences in type distributions were found between IDUs and other cases, in particular the concentration of emm/M83 (22% of IDUs, 2% of non-IDUs). These findings indicate that an epidemic of severe S. pyogenes infections in IDUs occurred in the UK, peaking in 2003. The explanation for this rise remains unclear.

Molecular characterization of methicillin-resistant Staphylococcus epidermidis strains from bacteraemic patients.

In order to study the clonality of clinical methicillin-resistant Staphylococcus epidermidis (MRSE) strains and their staphylococcal cassette chromosome mec (SCCmec) elements, 60 isolates of MRSE from bacteraemic patients in three units of the Helsinki University Hospital, Finland were selected, covering the periods 1990-1993 and 1997-1998. The MRSE strains were analysed by pulsed-field gel electrophoresis (PFGE), multilocus sequence typing and SCCmec typing. Eleven PFGE types (FIN-SE-1-11) with sequence type ST2 (clonal complex 2; CC2) were identified. The previously established methicillin-resistant Staphylococcus aureus SCCmec criteria were applied to name the MRSE SCCmec complexes, and it was found that 7% of the isolates carried SCCmec type IA (ccrA1, class B), whereas the majority (93%) yielded six non-typeable SCCmec PCR patterns (P1-P6). Within each SCCmec PCR pattern, two ccr recombinase genes (ccrA2 and ccrA3) and two mec gene complexes (class A and class B) were detected. In addition, the ccrC gene was associated with three of the six patterns. In conclusion, the MRSE strains were genetically related to each other (ST2) but their SCCmec complexes were unique combinations of elements previously recognized among SCCmec types III and IV.

Emergence and spread of vancomycin resistance among enterococci in Europe.

Nowadays, six types of acquired vancomycin resistance in enterococci are known; however, only VanA and to a lesser extent VanB are widely prevalent. Various genes encode acquired vancomycin resistance and these are typically associated with mobile genetic elements which allow resistance to spread clonally and laterally. The major reservoir of acquired vancomycin resistance is Enterococcus faecium; vancomycin-resistant Enterococcus faecalis are still rare. Population analysis of E. faecium has revealed a distinct subpopulation of hospital-acquired strain types, which can be differentiated by molecular typing methods (MLVA, MLST) from human commensal and animal strains. Hospital-acquired E. faecium have additional genomic content (accessory genome) including several factors known or supposed to be virulence-associated. Acquired ampicillin resistance is a major phenotypic marker of hospital-acquired E. faecium in Europe and experience has shown that it often precedes increasing rates of VRE with a delay of several years. Several factors are known to promote VRE colonisation and transmission; however, despite having populations with similar predispositions and preconditions, rates of VRE vary all over Europe.

Clonality of epidemic methicillin-resistant Staphylococcus aureus strains in Finland as defined by several molecular methods.

In Finland, the incidence of methicillin-resistant Staphylococcus aureus (MRSA) strains has increased ten fold within the last decade. In order to follow the changing epidemiology of MRSA, accurate typing of S. aureus strains is important. The purpose of this study was to reanalyse 44 previously recognised Finnish epidemic MRSA strains (EMRSA) by several molecular typing methods and to revise their nomenclature. The 44 EMRSA strains were grouped into 26 pulsed-field gel electrophoresis (PFGE) clusters, 20 multi locus sequence typing (MLST) sequence types (ST) belonging to 12 clonal complexes (CC) of which CC8 was the most prevalent, and 27 spa types belonging to four clonal complexes. The staphylococcal cassette chromosome mec (SCCmec) type IV was predominant, and 48% of the strains were nonmultiresistant to antibiotics. The discriminatory power of PFGE clusters, MLST, and spa typing was high. The overall concordance values of typing methods differed when assessed by two different methods. Adjusted Rand coefficient provided fairly low correlations for all comparisons. However, spa type was able to efficiently predict types and clonal complexes of most of the other methods with high probability (> or =80%).

Panton-Valentine leukocidin genes and staphylococcal chromosomal cassette mec types amongst Finnish community-acquired methicillin-resistant Staphylococcus aureus strains, 1997-1999.

Methicillin-resistant Staphylococcus aureus (MRSA) strains from Finland covering years 1997-1999 were studied for the presence of Panton-Valentine leukocidin (PVL) gene loci, and the clinically well-defined community-acquired MRSA (CA-MRSA) strains (n = 108) also for staphylococcal chromosomal cassette mec (SCCmec) and multilocus sequence types (MLST). Only a minority (12%) of the CA-MRSA strains contained the PVL gene loci and possessed genotypes formerly described as typical to CA-MRSA strains. The majority of these strains were heterogenous by MLST and pulsed-field gel electrophoresis (PFGE) analysis but, however, harboured the SCCmec cassette type IV. In conclusion, it seems doubtful to consider only molecular characteristics such as the presence of PVL genes as definite markers for CA-MRSA strains.

The epidemiology of severe Streptococcus pyogenes associated disease in Europe.

Several European countries reported outbreaks of severe disease caused by Streptococcus pyogenes in the late 1980s. This marked a departure from the previous decades, where very few such outbreaks were noted. These changes in disease occurrence formed part of a global phenomenon, the reasons for which have yet to be explained. Results of surveillance activities for invasive S. pyogenes infection within Europe over the past fifteen years identified further increases in many countries. However, variations in surveillance methods between countries preclude robust comparisons being made, illustrating the need for a unified surveillance strategy across Europe. This was finally embodied in the Strep-EURO programme, introduced in 2002.

Comparison of genotypes of methicillin-resistant and methicillin-sensitive Staphylococcus aureus in Finland.

The frequency of horizontal transfer of the staphylococcal cassette chromosome mec to methicillin-susceptible Staphylococcus aureus is unknown. In order to gain more information regarding this frequency in Finland, the genotypes of 299 clinical methicillin-sensitive Staphylococcus aureus isolates were compared to representatives of 24 epidemic methicillin-resistant Staphylococcus aureus genotypes. Sixty-eight percent of the methicillin-sensitive isolates had a genotype similar to eight of the epidemic methicillin-resistant strains. The remaining isolates (32%) showed 22 different genotypes. The results indicate that, in Finland, several methicillin-sensitive Staphylococcus aureus genotypes may have acquired the staphylococcal cassette chromosome mec.

Bacterial genotype affects the manifestation and persistence of bovine Staphylococcus aureus intramammary infection.

Two-hundred seventeen Staphylococcus aureus isolates from 116 dairy cows with intramammary infections were analyzed by pulsed-field gel electrophoresis to study the association between symptom severity, persistence of infection, and bacterial genotype. Among five main genotypes infecting 90% of the cows, one was associated with severe clinical symptoms but reduced persistence.

The epidemiology of severe Streptococcus pyogenes associated disease in Europe.

Several European countries reported outbreaks of severe disease caused by Streptococcus pyogenes in the late 1980s. This marked a departure from the previous decades, where very few such outbreaks were noted. These changes in disease occurrence formed part of a global phenomenon, the reasons for which have yet to be explained. Results of surveillance activities for invasive S. pyogenes infection within Europe over the past fifteen years identified further increases in many countries. However, variations in surveillance methods between countries preclude robust comparisons being made, illustrating the need for a unified surveillance strategy across Europe. This was finally embodied in the Strep-EURO programme, introduced in 2002.

Changing epidemiology of methicillin-resistant Staphylococcus aureus in Finland.

Data on methicillin-resistant Staphylococcus aureus (MRSA) cases notified to the National Infectious Disease Register (NIDR) and antibiotic resistance profiles of MRSA isolates sent to the national reference laboratory between 1997 and 2002 were analysed. In addition, the diagnostic methods used for MRSA identification in Finnish microbiology laboratories, the number of MRSA screening specimens studied, and the MRSA situation in long-term care facilities in 2001 were reviewed. MRSA cases notified to the NIDR rose from 120 in 1997 to 597 in 2002 (from 2.3 to 11.5 cases per 100,000 population). The increase was greatest in elderly people and outside Helsinki metropolitan area, in the districts where the proportion of non-multiresistant strains was most prominent. The National Committee for Clinical Laboratory Standard's guidelines for the oxacillin disk diffusion test were followed, except for the incubation temperature and time, which may have hindered detection of some MRSA strains. There was a wide geographic variation in the rates of MRSA, but this was not related to screening activity. MRSA isolates from long-term facilities accounted for more than half of the notifications to the NIDR in 2001.

Control of methicillin-resistant Staphylococcus aureus outbreak involving several hospitals.

This population-based, retrospective, cohort study describes a large methicillin-resistant Staphylococcus aureus (MRSA) epidemic caused by one strain (E1) in the greater Helsinki region. The epidemic comprised 210 cases at several hospitals, but was finally controlled. The study period ranged from June 1991 to December 2000. The epidemic peaked in 1993-1995 with 143 cases (68% of total cases). From August 1993, all MRSA-positive cases at the eight municipal hospitals were isolated and barrier nursed. Contacts were cohorted and screened for MRSA colonization. Decolonization treatment was administered to some chronic carriers. MRSA cases and contacts were identified in the joint patient register of the municipal hospitals from August 1993. The annual incidence of MRSA E1 in Helsinki City area per 100,000 inhabitants rose from 0.2 in 1991 to 13.6 in 1994. It decreased from 1995, reaching 0.7 per 100,000 in 2000. A jointly agreed policy on MRSA and timely co-operation between all units were essential for control of this epidemic.

Outbreak caused by tobramycin-resistant Pseudomonas aeruginosa in a bone marrow transplantation unit.

Between May and August 1995, 5 patients in a bone marrow transplantation (BMT) ward developed bacteremia caused by Pseudomonas aeruginosa resistant to tobramycin (TRPA). Previously, isolates of TRPA had been limited to patients who were treated in 1 intensive care unit (ICU) of this tertiary care teaching hospital in Helsinki, Finland. To study whether the outbreak was caused by a single or multiple strains of P. aeruginosa, 102 isolates of TRPA from clinical samples obtained from different hospital units and 22 isolates obtained from the hospital environment were characterized by pulsed-field gel electrophoresis. All isolates from hematological patients produced 1 unique fragment pattern, which was also isolated from 3 ICU patients before the BMT ward outbreak began as well as from 5 shower heads in the BMT ward. The outbreak in the BMT ward was successfully controlled by eradicating the probable environmental source--contaminated hand showers--but the endemic infections continued in the ICU.

Recognition of two groups of methicillin-resistant Staphylococcus aureus strains based on epidemiology, antimicrobial susceptibility, hypervariable-region type, and ribotype in Finland.

Epidemiological evidence suggests that some methicillin-resistant Staphylococcus aureus (MRSA) strains are more prone to dissemination than others. We studied 72 MRSA strains, collected through nationwide MRSA surveillance in 1992 through 1999 and known to be either (i) sporadic, (ii) local outbreak strains spread within one hospital, or (iii) epidemic strains spread among hospitals, by antimicrobial susceptibility testing, hybridization of the mec hypervariable region (HVR), and ribotyping. Our results show that two main groups can be identified among these strains. The first group includes mainly nonepidemic, nonmultiresistant MRSA strains showing a specific mec HVR hybridization pattern, A, in combination with a variety of ribotypes. The other group includes multiresistant strains with mec HVR hybridization pattern B or C in association with closely related ribotype a or b. Sixty-four percent (9 of 14) of Finnish epidemic MRSA strains belong to the latter group. These findings support the existence of differences in epidemic potential among MRSA strains.

Eradication of methicillin-resistant Staphylococcus aureus from a health center ward and associated nursing home.

BACKGROUND: Long-term health care facilities have been recognized as reservoirs of multiresistant bacterial strains, especially methicillin-resistant Staphylococcus aureus (MRSA). Efforts to control MRSA in this setting usually have been only partially effective. We describe herein the eradication of epidemic MRSA from a Finnish health care center ward and affiliated nursing home. METHODS: The methods to control MRSA included (1) contact isolation precautions, (2) screening for asymptomatic carriage, (3) eradication of carriage, and (4) education of staff on hygienic measures. The first 6 patients with MRSA-positive findings were referred without delay to the Infectious Diseases Unit of the adjacent university hospital for eradication treatment. Later, an isolation unit of 6 rooms was founded in the health care center, where the MRSA-colonized patients were nursed as a separate cohort until they, in succession, were referred to the Infectious Diseases Unit for decolonization. RESULTS: From May 20 through August 17, 1993, the epidemic MRSA strain was isolated from 8 long-term patients on the 40-bed ward of the health care center, 4 of the 59 residents of the nursing home, and 1 member of the staff. Eradication of carriage was successful in all except 1 patient with dementia, who was nursed in contact isolation in the health care center until his death 21 months later. CONCLUSIONS: It is possible to eradicate MRSA from a long-term health care facility even after 13 cases by applying strict control measures. Our experience may be valuable in the future decision-making process for control of new and more challenging multiresistant bacteria, eg, vancomycin-resistant strains of MRSA.

Epidemiological typing of Candida albicans from bloodstream infections by restriction enzyme analysis.

Candida albicans blood culture isolates (n = 142) from 130 patients treated in 7 acute care hospitals in Southern Finland between 1986 and 1995 were typed by restriction enzyme analysis (REA) with EcoRI and MspI. REA revealed 118 distinct DNA types: 13 were detected in > 1 patient and 105 DNA types were unique. Patients with identical DNA types were not temporally or geographically clustered. Among 11 patients with more than 1 C. albicans isolate during 1 episode of fungemia the DNA type remained the same, except in 1 patient. These results indicate that REA is a powerful tool for the epidemiological typing of C. albicans infections.