Prevalence of PER-1 Extended-Spectrum beta-Lactamase-Producing Clinical Isolates of Acinetobacter baumannii in a University Hospital, Busan, Korea / 대한임상미생물학회지

BACKGROUND: In recent years, Acinetobacter baumannii isolates acquired resistance to cefepime have increased significantly. The aim of this study was to survey the prevalence of PER-1 extendedspectrum beta -lactamase (ESBL)-producing A. baumannii isolates in a University Hospital, Busan, Korea. METHODS: Antimicrobial susceptibilities were tested by the disk diffusion method, and double disk synergy test was performed for screening of ESBL-production. MICs were determined by agar dilution method. The isoelectric points of beta -lactamases were determined by isoelectric focusing. Transferability of cefepime-resistance were tested by conjugation. blaPER-1 and blaPER-2 alleles were detected by PCR, and the DNA sequences of amplified products were determined by using the dideoxy-chain termination method. RESULTS: Among 51 clinical isolates of A. baumannii intermediate or resistant to cefepime, 10 isolates (19.6%) showed positive results in double disk synergy test. PCR-based experiments detected blaPER-1 gene in all the 10 isolates. All the isolates contained three beta -lactamase bands: pI 5.3, 7.9, and 9.4. MICs of ampicillin, piperacillin, cephalothin, cefoxitin, cefoperazone, ceftazidime, cefotaxime, cefepime, and aztreonam were >256 mg/L, respectively, and them of imipenem were 8-16 mg/L. CONCLUSION: The prevalence of PER-1-producing A. baumannii strains in Busan was less than that of in Seoul. But an outbreak of infection caused by this strain in an intensive care unit shows that spread of PER-1-producing A. baumannii strains can be anticipated in a near future. Prevention of hospital infection by these resistant microorganisms are needed.

Molecular Epidemiology of Vancomycin-resistant Enterococci Isolated from Patients in a Neonatal Intensive Care Unit / 대한임상병리학회지

BACKGROUND: Recently, an acquired resistance to vancomycin in enterococci has become a serious clinical problem. For the prevention of further propagation of vancomycin-resistant enterococci (VRE), epidemiological study of the infection is essential, but studies on the VRE infection are rare in Korea. We conducted an analysis of the epidemiology of a VRE outbreak in a neonatal intensive care unit (NICU) to clear up the route of propagation of the VRE. METHODS: Vancomycin-resistant Enterococcus faecium (VREFM) strains were isolated from urine specimens of seven patients, rectal swabs from seven patients, and three skin swabs from two patients in the Kosin Medical Center neonatal intensive care unit, Pusan, Korea. Antimicrobial susceptibilities were tested by a disk diffusion method and agar dilution method. Genotypes of vancomycin-resistance were determined by PCR and SmaI-digested genomic enterococcal DNAs were analyzed by pulsed-field gel electrophoresis. RESULTS: All of the 17 strains of VREFM were resistant to ampicillin, vancomycin, and teicoplanin and they showed the same genotype (vanA). SmaI-digested genomic DNAs of seven strains isolated from urine were typed as I (1), II (1), IIIb (4), and IV (1). Three strains from skin swabs were I (2) and II (1). Six strains from rectal swabs were I (2), II (1), and IIIa (3). Genomic DNA typing of one isolate from a rectal swab failed. Each genomic DNA type of VREFM strains isolated from skin swabs of two patients were the same with those from urine specimens as I and II, respectively. CONCLUSIONS: This study suggests that VRE strains colonized in the intestines can cause infections after skin colonizing and can be transmitted/propagated to other people through skin contact. In conclusion, it is important for the prevention of the dissemination of VRE that controls for patients' skin hygiene, as well as hand washing by medical persons, be put in place.