Pseudo-outbreak of Stenotrophomonas maltophilia Due to Contamination of Bronchoscope / 대한진단검사의학회지

BACKGROUND: We noticed an abrupt increase in the isolation of Stenotrophomonas maltophilia from bronchoalveolar lavage (BAL) specimens collected at Chosun University Hospital. We performed surveillance cultures in order to identify the source of what appeared to be a pseudo-outbreak. METHODS: To investigate a possible nosocomial outbreak of S. maltophilia, we performed culture of 11 environmental specimens obtained from a bronchoscopy room and two bronchoscopes. Pulsedfield gel electrophoresis (PFGE) was used to examine the genetic relatedness among the strains of S. maltophilia recovered from BAL specimens of 3 patients and 1 environmental sample, as well as 9 unrelated strains of S. maltophilia as a control. RESULTS: During a 7 day-period in March 2006, S. maltophilia was isolated from the BAL specimens of 7 of 13 (54%) patients, compared to only 5 of 188 (2.6%) patients during the 6-month period prior to that period. S. maltophilia was isolated from 1 of the 11 environmental samples, which was obtained from a fiberoptic bronchoscope suction channel. All 7 patient isolates and one environmental isolate exhibited similar antibiotic susceptibility patterns. PFGE analysis of the genomic DNA from epidemic strains demonstrated an identical banding pattern, whereas each of epidemiologically unrelated strains showed a unique electrophoretic pattern. CONCLUSIONS: Apparently one of the hospital bronchoscopes became contaminated with S. maltophilia during a bronchoscopic procedure. It is likely that subsequent specimen contamination occurred because the bronchoscope had been inadequately cleaned and disinfected. The pseudo-outbreak was controlled successfully by removing the source of infection.

Trends of the Species and Antimicrobial Susceptibility of Microorganisms Isolated from Blood Cultures of Patients / 대한임상미생물학회지

BACKGROUND: Blood culture is an important procedure for the determination of the etiologic agent of septicemia. Analysis of the blood culture results can provide clinicians with very important information for the empirical treatment of patients. METHODS: In this study the blood cuture results at Chosun University Hospital during the years 2002 to 2005 were analysed to determine the species and antimicrobial susceptibility of the isolates. Blood culture bottles were incubated in BACTEC 9240 blood culture system; the isolates were identified by Vitek II, and antimicrobial susceptibility was tested by Vitek II system or the NCCLS disk diffusion method. RESULTS: Positive blood cultures were obtained from 1,520 (18.5%) patients. Among the microorganisms isolated from blood culture, 97.0% were aerobic and facultative anaerobic bacteria and 2.8% were fungi. Frequently isolated organisms in decreasing order were coagulase-negative staphylococci (CNS), Escherichia coli, Staphylococus aureus, Stenotrophomonas maltophilia, Serratia marcescens, and Klebsiella pneumoniae. The proportion of Pseudomonas aeruginosa isolates resistant to ceftazidime and imipenem was increased during the study period. CONCLUSION: E. coli was the most frequent etiologic agent of bacteremia except CNS, common contaminants of skin, at Chosun University Hospital. It seems to be necessary to enhance infection control measures to cope with an increasing number of the resistant bacteria to various antibiotics.

Usefulness of Serum Cystatin C for the Evaluation of Renal Function in Diabetic Patient / 대한진단검사의학회지

BACKGROUND: Diabetic nephropathy is the most frequent complication in patients with diabetes mellitus (DM). In clinical practice, the glomerular filtration rate (GFR) is often estimated from serum creatinine. Recently, serum cystatin C has been suggested being a better parameter for diagnosis of impaired renal function. We evaluated serum cystatin C as a potential new marker of GFR in diabetes patients. METHODS: Serum cystatin C and serum creatinine (sCr) were measured in 73 DM patients to evaluate their usefulness in diabetic patients. DM patients were divided into three groups (whole DM patients, albuminuric patients, and DM patients with sCr<1 mg/dL). Serum cystatin C and sCr were compared with creatinine clearance (CCr). RESULTS: The overall correlation coefficient for the reciprocal of serum cystatin C was superior to that of the reciprocal of serum creatinine in all three patient groups. With CCr cut-off values of 60 mL/min and 80 mL/min, receiver operating characteristic (ROC) plotting demonstrated that serum cystatin C had a higher sensitivity and specificity for detecting decreased GFR than did serum creatinine in all three patient groups. CONCLUSIONS: These findings suggest that serum cystatin C is superior to serum creatinine as a marker of GFR measured by correction or mean ROC-plot AUC in diabetic patients; therefore, serum cystatin C could be used for the early detection of the impairment of renal function.

Evaluation of the detectability of Vitek II System for Inducible Clindamycin Resistance in Staphylococci / 대한진단검사의학회지

BACKGROUND: While broth based antimicrobial susceptibility test methods work well for the detection of the majority of antimicrobial resistance mechanisms, antimicrobial resistance mechanism in some microorganisms may not be detected by these methods. The purpose of this study was to compare Vitek II system with a standard method for the ability to detect inducible clindamycin resistance in Staphylococcus aureus. METHODS: Of 200 clinical isolates of S. aureus tested, 183 were methicillin resistant (MRSA) and 17 were methicillin susceptible (MSSA). A disk approximation test (Clinical Laboratory Standards Institute; CLSI, Wayne, PA, USA) was performed as the standard method by placing standard erythromycin and clindamycin disks in adjacent positions. Vitek II ID-GPI (bioMerieux, Durham, NC, USA) was used for identification and Vitek AST-P536 (bioMerieux, Durham, NC, USA) for antimicrobial susceptibility tests. RESULTS: Clindamycin resistance rates of S. aureus tested by disk diffusion and Vitek II system were 89% and 56%, respectively. All but one inducible clindamycin resistant MRSA isolates were susceptible to clindamycin by Vitek II system. Five inducible clindmycin resistant MSSA isolates were all susceptible to clindamycin by Vitek II system. Vitek II system did not detect the inducible clindamycin resistance in S. aureus. CONCLUSIONS: Our results showed that Vitek II system was unacceptable for the detection of inducible clindamycin resistance in S. aureus. We suggests that the disk approximation test should be used to detect the inducible clindamycin resistance in S. aureus.