Changes in the aerobic faecal flora of patients treated with antibiotics for acute intra-abdominal infection.

BACKGROUND: An open observational study was performed to investigate changes in the rectal flora and antibiotic susceptibility among faecal bacteria in patients treated with antibiotics for acute intra-abdominal infection. METHODS: One hundred and forty patients with acute intra-abdominal infection requiring antibiotic treatment and hospitalization were included. Eight surgical units from the southern part of Sweden participated, between January 2006 and November 2007. Antibiotic treatments were according to local guidelines. Rectal swabs were obtained on admission (sample 1) and 2-14 days after the end of antibiotic treatment (sample 2). Aerobic bacteria and yeasts were analysed. The material was divided into 2 groups: 1 group with Enterobacteriaceae and 1 group with non-fermentative Gram-negative bacteria. The susceptibility to antibiotics in each group was compared between samples 1 and 2. RESULTS: The main finding of this study on patients with severe intra-abdominal infections was a shift in the aerobic faecal flora following antibiotic treatment, from Escherichia coli to other more resistant Enterobacteriaceae, Enterococcus faecium, and yeasts. The susceptibility to cephalosporins and piperacillin-tazobactam decreased in Enterobacteriaceae. CONCLUSIONS: Following antibiotic treatment, a shift in the aerobic rectal flora to species with intrinsic antibiotic resistance was observed. This indicates that the emergence of resistance is not due to new mutations, but rather to selection of more resistant species. This should be taken into account when designing treatments for secondary intra-abdominal infections.

Epidemiological typing of methicillin-resistant Staphylococcus aureus (MRSA): spa typing versus pulsed-field gel electrophoresis.

Molecular methods based on sequencing, such as spa typing, have facilitated epidemiological typing of bacterial isolates compared to the gold standard pulsed-field gel electrophoresis (PFGE), a technically more demanding method. We studied methicillin-resistant Staphylococcus aureus (MRSA) in 4 Swedish counties from 2003 through 2005, and compared spa typing and PFGE results to epidemiological data. Of 280 MRSA isolates, 91 were from sporadic cases and 189 were associated with 35 outbreaks. A total of 50 spa types and 74 PFGE patterns were detected. 60 (21%) of the MRSA isolates carried the Panton-Valentine leukocidin (PVL) genes. 12 of the PVL-positive MRSA were healthcare associated. 25 of the spa types and 31 of the PFGE patterns were associated with outbreaks. In 1 of the outbreaks we found isolates with different but closely related spa types, and in 6 of the outbreaks we observed isolates with different but related PFGE patterns. In this low-endemic setting, with outbreaks limited in time and place, we found spa typing to be a useful tool for epidemiological typing of MRSA, due to its rapidity, accessibility, ease of use, and standardized nomenclature.

Wound contamination in cardiac surgery. A systematic quantitative and qualitative study of the bacterial growth in sternal wounds in cardiac surgery patients.

OBJECTIVES: To investigate the degree of bacterial contamination in the sternal wound during cardiac surgery and the sternal skin flora after operation in order to increase our understanding of the pathogenesis of sternal wound infections. DESIGN: Prospective study where cultures were taken peri- and postoperatively from sternal wounds and skin. SETTING: University Hospital. PATIENTS: 201 cardiac surgery patients. RESULTS: 89% of the patients grew bacteria from the subcutaneous sternal tissue. 98% of the patients showed bacterial growth on the surrounding skin at the end of the operation. We found both commensal and nosocomial bacteria in the sternal wound. These bacteria had different temporal distribution patterns. Coagulase-negative staphylococci (CoNS) and Propionibacterium acnes (PA) were by far the most prevalent bacteria during and after the operation. Furthermore, 41% of patients had more than 10,000 CFU/pad CoNS on the skin. There was no correlation between length of operation and number of bacteria. Men displayed higher bacterial counts than women on the skin. CONCLUSION: Skin preparation with ethanol/chlorhexidine is unable to suppress the physiological skin flora for the duration of a heart operation. A decrease of CoNS and PA postoperatively can be caused by competitive recolonisation of commensal and nosocomial bacteria.

Modified pulsed-field gel electrophoresis protocol for typing of enterococci.

Controlling the spread of vancomycin-resistant enterococci (VRE) is an important task in hospital epidemiology. Pulsed-field gel electrophoresis (PFGE) has become the golden standard for molecular epidemiological characterisation of enterococcal isolates. For separation of DNA fragments by PFGE, different electrophoresis conditions have been recommended, but none of these protocols allows a satisfactory separation of both small and large DNA fragments of enterococci simultaneously. In this study we have speeded up the preparation of chromosomal DNA and defined new electrophoresis conditions that enhance separation of small and large DNA fragments for subtyping of enterococci with a 24 h PFGE.

Compliance with hygiene guidelines: the effect of a multimodal hygiene intervention and validation of direct observations.

BACKGROUND: Good compliance with hygiene guidelines is essential to prevent bacterial transmission and health care-associated infections. However, the compliance is usually <50%. METHODS: A multimodal and multidisciplinary hygiene intervention was launched once the baseline compliance was determined through direct observations in 4 departments of obstetrics and gynecology. Detailed evaluations of the compliance rates were performed at point of stability (at 80%) and follow-up (3 years after hygiene intervention). Validation of direct observations was performed using blinded double appraisal and multiappraisal. RESULTS: At baseline, the compliance with barrier precautions and the dress code at the 4 departments were 39% to 47% and 79% to 98%, respectively. Point of stability was reached approximately 1 year after the hygiene intervention was launched. The compliance with barrier precautions was significantly higher at follow-up compared with baseline in 3 departments. In the validation by double appraisal, 471 of 483 components were judged identical between observers. In the multiappraisal, 95% to 100% of the observers correctly judged the 7 components. CONCLUSION: It is possible to improve compliance with hygiene guidelines, but, to ensure a long-lasting effect, a continuous focus on barrier precautions is required. Observation is a valid method to monitor compliance.

The effect of improved compliance with hygiene guidelines on transmission of Staphylococcus aureus to newborn infants: the Swedish Hygiene Intervention and Transmission of S aureus study.

BACKGROUND: Newborn infants are often colonized with Staphylococcus aureus originating from health care workers (HCWs). We therefore use colonization with S aureus of newborn infants to determine the effect of an improved compliance with hygiene guidelines on bacterial transmission. METHODS: Compliance with hygiene guidelines was monitored prior to (baseline) and after (follow-up) a multimodal hygiene intervention in 4 departments of obstetrics and gynecology. spa typing was used to elucidate transmission routes of S aureus collected from newborn infants, mothers, fathers, staff members, and environment. RESULTS: The compliance with hygiene guidelines increased significantly from baseline to follow-up. The transmission of S aureus from HCWs to infants was however not affected. Fathers had the highest colonization rates. Persistent carriage was indicated in 18% of the HCWs. The most commonly isolated spa type was t084, which was not detected in a previous study from the same geographic area. CONCLUSION: It is possible to substantially improve the compliance with hygiene guidelines, by using multimodal hygiene intervention. The improved compliance did not decrease the transmission of S aureus from sources outside the own family to newborn infants. Furthermore, we show the establishment of a new spa type (t084), which now is very common in our region.

A clonal outbreak of methicillin-susceptible Staphylococcus aureus with concomitant resistance to erythromycin, clindamycin and tobramycin in a Swedish county.

In contrast to methicillin-resistant Staphylococcus aureus (MRSA), studies on clonal distribution of methicillin-susceptible S. aureus (MSSA) are scarce. Since 2004, an increasing incidence of concomitant resistance to erythromycin, clindamycin and tobramycin (ECT) among MSSA has been detected in Ostergotland County, Sweden. The objectives of this study were to investigate the genetic relatedness among these isolates with 2 genotyping methods, pulsed-field gel electrophoresis (PFGE), and sequence-based typing of the polymorphic region X of the staphylococcal protein A gene (spa typing), and to determine the incidence of the Panton-Valentine leukocidin (PVL) gene. When genotyping 54 ECT-resistant MSSA isolates from 49 patients (1 isolate per patient per y), 91% were shown to be part of a clonal outbreak with both methods used (spa type t002). The clonal outbreak was concentrated in 8 hospital departments and 2 primary care centres, all located in the city of Linkoping. All isolates were negative for the PVL gene. In conclusion, this study demonstrates an ongoing clonal outbreak of PVL-negative ECT-resistant MSSA. This stresses the need to continuously maintain basic hygiene rules, since nosocomial transmission of pathogens is not limited to known resistant bacteria such as MRSA.

Rectal colonization and frequency of enterococcal cross-transmission among prolonged-stay patients in two Swedish intensive care units.

The aims of this study were to gain insight into the dynamics of the rectal flora during prolonged ICU stay, with a particular focus on colonization and cross-transmission with resistant pathogens, and to evaluate methods for the rapid isolation of relevant bacteria from rectal swabs. Patients admitted to a general intensive care unit (GICU) or a cardiothoracic ICU (TICU) at the University Hospital of Linköping, Sweden, between 1 November 2001 and January 2002 with a length of stay > 5 d were included (n = 20). Chromogenic UTI agar medium was used for discrimination of different species, and appropriate antibiotics were added to detect resistance. Direct plating was compared to enrichment broth for a subset of specimens. The study showed an early alteration in rectal flora, with a dramatic decrease in Gram-negative rods in favour of Gram-positive bacteria. An ampicillin- and high-level gentamicin resistant clone of Enterococcus faecium was found in 6 of 10 patients in the GICU and 2 of 11 patients in the TICU. Enrichment broth did not enhance the detection of Gram-negative bacteria compared to direct plating on Chromogenic UTI medium, but enrichment broths were needed for optimal detection of resistant Gram-positive bacteria.

Blood exposure: factors promoting health care workers' compliance with guidelines in connection with risk.

BACKGROUND: Health care workers compliance with guidelines, universal precautions, in connection with tasks that could involve contact with patient's blood is unsatisfactory. In a previous paper, we identified different forces that undermine compliance. Socialization into infection control, routinization, stereotyping, perceptions of patients' wishes and the presence of competing values and norms are examples of such forces. AIMS AND OBJECTIVES: The aim of this article is to describe and analyse different forces that promote adherence to universal precautions. Behavioural variations are seen as a consequence of differences between wards with regard to the safety culture. Safety culture is conceptualized as the outcome of a constant interplay between deactivating and reactivating forces. In this article the focus is on the latter. METHOD: The grounded theory approach. Data were collected through interviews with nurses and assistant nurses. RESULTS: The charge nurse, informal leaders, students, infection control nurses, type of work, availability of equipment, blood-exposure incidents and media-coverage of infectious diseases are described as potentially important for compliance. The properties these agents must possess in order to be influential are also described. RELEVANCE TO CLINICAL PRACTICE: The outcome of an occupationally acquired infection can be fatal. Hence it is important that health care workers take protective measures. The results imply that mere information about safe practices alone is insufficient to achieve that goal. All factors of importance for compliance must be taken in to consideration in clinical work and in education.

Health care workers' action strategies in situations that involve a risk of blood exposure.

Previous research shows that health care workers (HCWs) often act in a risky way in blood-exposure situations, and thereby run the risk of becoming infected by blood-borne pathogens. A qualitative study was conducted in order to describe factors that influence HCWs' actions in such situations. Nurses and nursing assistants were interviewed. The analysis shows that HCWs perceive that there is a conflict among different demands. These demands are protecting the patient's privacy, protecting themselves from being infected and respecting the norms of the department. The process of managing this conflict is labelled 'balancing', which most often results in the choice of a diagnosis-related strategy.

Division of the genus Enterococcus into species groups using PCR-based molecular typing methods.

Broad-range 16S rDNA PCR (BR-PCR) applied to DNA from 32 clinical enterococcal isolates and 12 other enterococci from a clinical reference collection followed by species-specific hybridization analysis identified 25 strains of Enterococcus faecalis and 19 Enterococcus species. Randomly amplified polymorphic DNA (RAPD) analysis using UPGMA clustering on the same material revealed four different clusters at a similarity level of 49%. Based on partial 16S rDNA sequence analysis of variable regions V4 and V9, it was possible to divide the 19 type strains specifying the genus Enterococcus into 12 different 16S rDNA species groups. The type strain distribution then served as a template for the analysis of the other 44 strains which were assigned to four different species groups (a-d) based on their 16S rDNA motifs. There was good agreement with the RAPD clusters. Species group a was an individual species line containing 25 strains that were identified as E. faecalis. Group b also represented an individual species line of 12 strains identified as E. faecium. The remaining seven strains that formed species groups c and d could not be fully identified to species by this analysis. It was concluded that BR-PCR of 16S rDNA followed by partial sequence analysis of the PCR products is a reliable technique for the identification and classification of enterococci. Further division of unresolved species groups should be achievable if regions other than V4 and V9 of 16S rDNA are also analysed.

Genetic relatedness of Enterococcus faecalis isolates with high-level gentamicin resistance from patients with bacteraemia in the south east of Sweden 1994-2001.

High-level gentamicin resistant (HLGR) enterococci (Enterococcus faecalis and Enterococcus faecium) have become a substantial nosocomial problem in many countries. In this study, we investigated the prevalence of HLGR enterococci and their genetic relatedness in blood culture isolates from patients with bacteraemia admitted to the 3 hospitals in Ostergötland, a county in the south east of Sweden, during 1994-2001. 36 of 250 E. faecalis (14%,) and 4 of 106 E. faecium isolates (4%) were shown by PCR to carry the aac(6')-Ie-aph(2")-Ia aminoglycoside modifying gene and these isolates were also classified as HLGR enterococci by the gentamicin antibiotic disk diffusion method. A majority of HLGR E. faecalis isolates (83%) belonged to the same cluster of genetically related isolates, according to the pulsed-field gel electrophoresis (PFGE) patterns, whereas all 4 HLGR E. faecium isolates had unique PFGE patterns. In conclusion, our study showed that in contrast to studies from many other countries, the presence of HLGR enterococci was more common in E. faecalis than in E. faecium and appeared the first time in 1996 and 1999, respectively. Bacteraemia with HLGR enterococci in Ostergötland was mainly due to the spread of a cluster of related E. faecalis strains.

Genetic relatedness among Enterococcus faecalis with transposon-mediated high-level gentamicin resistance in Swedish intensive care units.

We studied 45 isolates of Enterococcus faecalis with high-level gentamicin resistance (HLGR), all but one concomitantly resistant to ciprofloxacin, and 25 ciprofloxacin-resistant isolates without HLGR for genetic relatedness using pulsed-field gel electrophoresis (PFGE). E. faecalis were isolated from patients admitted to intensive care units at eight hospitals in southern Sweden from December 1996 through December 1998. Genomic analysis by PFGE resulted in three clusters of genetically related isolates (designated clusters I, II and III) and 23 unique clones. Cluster I was found predominantly in the eastern and central parts of southern Sweden and clusters II and III in south-western Sweden. Among the 45 isolates with HLGR, 69% belonged to cluster I, 20% to cluster II, and 11% had unique PFGE patterns, which suggests that the majority of isolates with HLGR are closely related. Among the 25 ciprofloxacin-resistant isolates without HLGR, 68% had unique PFGE patterns, 12% belonged to cluster I and 20% to cluster III, which suggests the ciprofloxacin-resistant isolates are not related. All isolates with HLGR contained the aac(6')Ie-aph(2")Ia gene, which was carried on a Tn5281-like transposon in all isolates except one. We conclude that HLGR in E. faecalis was mainly due to dissemination of genetically related clones during the time studied, and that HLGR in these isolates was due to the presence of the aac(6')Ie-aph(2")Ia gene.