Ping-Cherng Chiang

Extended epidemic of nosocomial urinary tract infections caused by Serratia marcescens.

ABSTRACT In recent years a significant increase in the incidence of Serratia marcescens infections was noted at the Chang Gung Memorial Hospital, Taoyuan, Taiwan. A review of laboratory (1991 to 2002) and infection control (1995 to 2002) records showed the possibility of an extended epidemic of nosocomial urinary tract infections (UTIs) caused by S. marcescens. Therefore, in 1998 and 1999, 87 isolates were collected from patients with such infections and examined and another 51 isolates were collected in 2001 and 2002. The patients were mostly elderly or the infections were associated with the use of several invasive devices. S. marcescens was usually the only pathogen found in urine cultures in our study. Neither prior infections nor disseminated infections with the organism were observed in these patients. Resistance to most antibiotics except imipenem was noted. Two genotyping methods, pulsed-field gel electrophoresis and infrequent-restriction-site PCR, were used to examine the isolates. A total of 12 genotypes were identified, and 2 predominant genotypes were found in 72 (82.8%) of the 87 isolates derived from all over the hospital. However, 63.9% of the isolates of the two genotypes were from neurology wards. A subsequent intervention by infection control personnel reduced the infection rate greatly. The number and proportion of the two predominant genotypes were significantly reduced among the 51 isolates collected in 2001 and 2002. Thus, a chronic and long-lasting epidemic of nosocomial UTIs caused by S. marcescens was identified and a successful intervention was carried out. Both a cautious review of laboratory and infection control data and an efficient genotyping system are necessary to identify such a cryptic epidemic and further contribute to the quality of patient care.

Multidrug resistant Acinetobacter baumannii: risk factors for appearance of imipenem resistant strains on patients formerly with susceptible strains.

Background Multidrug resistant Acinetobacter baumannii (MDRAB) is an important nosocomial pathogen usually susceptible to carbapenems; however, growing number of imipenem resistant MDRAB (IR-MDRAB) poses further clinical challenge. The study was designed to identify the risk factors for appearance of IR-MDRAB on patients formerly with imipenem susceptible MDRAB (IS-MDRAB) and the impact on clinical outcomes. Methodology/Principal Findings A retrospective case control study was carried out for 209 consecutive episodes of IS-MDRAB infection or colonization from August 2001 to March 2005. Forty-nine (23.4%) episodes with succeeding clinical isolates of IR-MDRAB were defined as the cases and 160 (76.6%) with all subsequent clinical isolates of IS-MDRAB were defined as the controls. Quantified antimicrobial selective pressure, “time at risk”, severity of illness, comorbidity, and demographic data were incorporated for multivariate analysis, which revealed imipenem or meropenem as the only significant independent risk factor for the appearance of IR-MDRAB (adjusted OR, 1.18; 95% CI, 1.09 to 1.27). With selected cases and controls matched to exclude exogenous source of IR-MDRAB, multivariate analysis still identified carbapenem as the only independent risk factor (adjusted OR, 1.48; 95% CI, 1.14 to 1.92). Case patients had a higher crude mortality rate compared to control patients (57.1% vs. 31.3%, p = 0.001), and the mortality of case patients was associated with shorter duration of “time at risk”, i.e., faster appearance of IR-MDRAB (adjusted OR, 0.9; 95% CI, 0.83 to 0.98). Conclusions/Significance Judicious use of carbapenem with deployment of antibiotics stewardship measures is critical for reducing IR-MDRAB and the associated unfavorable outcome.

Clinical manifestations, antibiotic susceptibility and molecular analysis of Mycobacterium kansasii isolates from a university hospital in Taiwan

OBJECTIVES Mycobacterium kansasii causes a variety of infections. Although previous reports on the prognosis of antimicrobial therapy have been mostly satisfactory, problems involving treatment failure or relapse have been encountered. The purpose of this study was to establish a relationship between the clinical treatment outcomes of M. kansasii infections and bacterial drug susceptibility, and their clonality. METHODS A total of 37 M. kansasii clinical isolates and clinical information on 34 patients were retrospectively collected in a tertiary medical centre in Taiwan. Bacterial drug susceptibility was determined by the microdilution method. The phylogenetic relationship was analysed by PFGE analysis. RESULTS Results of PFGE typing revealed a major cluster (cluster I) and eight other divergent patterns. Two/three strains leading to treatment failure were also multidrug resistant and belonged to cluster I. CONCLUSIONS A relationship between high drug resistance and genetic relatedness of some M. kansasii strains was established. This was associated with clinical treatment failure.

Outbreak of Serratia marcescens postsurgical bloodstream infection due to contaminated intravenous pain control fluids.

BACKGROUND Serratia marcescens is an important nosocomial pathogen causing significant outbreaks. Here we report an outbreak of bloodstream infection caused by S. marcescens at a 3500-bed hospital in Taiwan. The effective cooperative efforts of both laboratory personnel and infection control practitioners (ICPs) jointly contributed to the total control of the outbreak. METHODS A sudden increase in the isolation of S. marcescens from blood cultures was noted in the Clinical Microbiology Laboratory. The information was passed to the ICPs and an investigation was initiated. Pulsed-field gel electrophoresis was used to study the relationships among the isolates. RESULTS Pulsotype A was identified in 43 (82.7%) of the 52 blood isolates studied. They were isolated from 52 patients distributed across 22 wards that were surveyed by seven ICPs. All patients had undergone surgery before the infection, and fentanyl-containing intravenous fluids were used for pain control in 43 of them. Isolates from 42 belonged to pulsotype A. Three S. marcescens isolates, all from fentanyl-containing fluids and demonstrating pulsotype A, were identified from 251 environmental cultures. All fentanyl-containing fluids that were in use were withdrawn and the outbreak was stopped. CONCLUSIONS The outbreak of S. marcescens bloodstream infection apparently occurred through the use of fentanyl-containing fluids contaminated by a pulsotype A S. marcescens.