Yu-Hui Lin

Antimicrobial susceptibility of clinical isolates of Acinetobacter baumannii

The in-vitro activity of 18 antimicrobial agents alone or in combination against 248 clinical isolates of Acinetobacter baumannii from Taiwan were tested by agar dilution. The MIC90S of ampicillin, amoxicillin, piperacillin, cefuroxime, cefotaxime, ceftriaxone, gentamicin, and amikacin were at least 128 mu g/ml. Ceftazidime, cefepime, sulbactam, clavulanic acid, and tazobactam presented moderate activity with MIC90S of 32, 16, 16, 32, and 32 mu g/ml, respectively. The increased activity of ampicillin/sulbactam, amoxicillin/clavulanic acid, and piperacillin/tazobactam was due to the intrinsic effect of sulbactam, clavulanic acid, and tazobactam, respectively. Imipenem, meropenem, and ciprofloxacin were the most active antimicrobial agents with MIC90S of 1, 1, and 0.5 mu g/ml, respectively. Nineteen isolates (7.7%) were resistant to all aminoglycosides and beta-lactam antibiotics, except carbapenems and ciprofloxacin. We are concerned about the multidrug resistance of A. baumannii in this study.

Comparison of susceptibility to extended-spectrum β-lactam antibiotics and ciprofloxacin among gram-negative bacilli isolated from intensive care units

The in vitro activities of extended-spectrum beta-lactam antibiotics (including piperacillin, cefotaxime, ceftriaxone, ceftazidime, cefepime, imipenem, and meropenems) were assessed and compared with the activity of ciprofloxacin against 366 clinical Gram-negative bacilli isolates from the intensive care units of Taichung Veterans General Hospital. The most prevalent species isolated were Pseudomonas aeruginosa and Acinetobacter baumannii. The activities of ceftazidime, cefepime, imipenem, and meropenem against these isolates were comparable to that of ciprofloxacin. Meropenem was found to be the most potent extended-spectrum beta-lactam antibiotic tested and the MIC50s and MIC90s for most of these multiresistant strains were lower than those of imipenem, ceftazidime, and cefepime, except for Stenotrophomonas maltophilia. The extended-spectrum beta-lactam antibiotics that were still active against S. maltophilia were piperacillin and ceftazidime. More than 50% of Enterobacter spp. were resistant to third-generation cephalosporins and piperacillin, but they remained susceptible to carbapenems and cefepime.

Comparison of polymerase chain reaction and pulsed-field gel electrophoresis for the epidemiological typing of Campylobacter jejuni

Seventeen sporadic Campylobacter jejuni enteritis cases occurred in Taichung City, Taiwan between July 1995 and September 1995. Pulsed-field gel electrophoresis (PFGE) and enterobacterial repetitive intergenic consensus (ERIC-1) primed polymerase chain reaction (PCR) techniques were compared for the epidemiological typing of the 17 C. jejuni isolates. Fourteen distinct PFGE fingerprint patterns were observed. Fifteen distinct PCR fingerprint patterns were demonstrated. Two clusters of isolates (isolates 5 and 6; isolates 10, 11 respectively) were found to be genetically indistinguishable by both methods. In conclusion, we consider that PFGE is a highly reproducible method for determining the relatedness among the C. jejuni isolates in this study, although their limited numbers of restriction fragments may reduce the discriminatory power. Although less reproducible than PFGE typing, ERIC-1 primed PCR can be used as a simple and rapid tool to discriminate different strains of C. jejuni.

Comparison of polymerase chain reaction and pulsed-field gel electrophoresis for the epidemiological typing of Alcaligenes xylosoxidans subsp. xylosoxidans in a burn unit.

Eighteen isolates of Alcaligenes xylosoxidans subsp. xylosoxidans were collected from clinical specimens of 15 patients in a burn unit and a plastic surgery ward over a 16-month period. Pulsed-field gel electrophoresis and polymerase chain reaction (PCR) were compared for the epidemiologic typing of these 18 isolates and fifteen epidemiologically unrelated strains. These 18 isolates demonstrated an identical fingerprint pattern and were easily distinguished from the 15 epidemiologically unrelated strains by pulsed-field gel electrophoresis typing and both enterobacterial repetitive intergenic concensus and repetitive extragenic palindrome-primed PCR fingerprinting. We conclude that pulsed-field gel electrophoresis analysis of XbaI-digested genomic DNA is a highly discriminatory and reproducible method for epidemiological typing of A. xylosoxidans subsp. xylosoxidans isolates. However, poor resolution due to frequent cutting in the smaller fragments (< 145.5 Kb) may lead to difficulty in interpretation. PCR is a rapid and highly discriminatory, but less reproducible, technique with occasional loss of major bands. The fingerprints produced by repetitive extragenic palindrome primed PCR had more intense bands and were easier to read than those produced by enterobacterial repetitive intergenic concensus-primed PCR in this study.

Molecular epidemiology of penicillin-resistant Streptococcus pneumoniae isolated in central Taiwan

Previous studies have suggested that penicillin-resistant pneumococcal isolates (especially those with MIC > 1 microgram/mL) usually are clonally related. To test this hypothesis, the molecular epidemiology of 29 clinical isolates of penicillin-resistant pneumococci (of which 83% were also resistant to either cefotaxime or ceftriaxone) collected in central Taiwan was investigated by pulsed field gel electrophoresis. Twenty-seven distinct patterns were identified. Our results indicate that an increase in penicillin-resistant S. pneumoniae between April 1993 and June 1994 in central Taiwan is not due to the clonal dissemination of a limited number of epidemic strains.

Gonococcal meningitis and intra-abdominal abscess in the presence of a ventriculoperitoneal shunt.

We report a case of gonococcal meningitis with an intraabdominal abscess in a 19-y-old woman, who had a ventriculoperitoneal shunt after craniotomy for astrocytoma. Percutaneous drainage was performed for the intraabdominal abscess. Ceftriaxone was administered with the ventriculoperitoneal shunt removal. The clinical course improved, but visual impairment last for 3 months following treatment.We report a case of gonococcal meningitis with an intraabdominal abscess in a 19-y-old woman, who had a ventriculoperitoneal shunt after craniotomy for astrocytoma. Percutaneous drainage was performed for the intraabdominal abscess. Ceftriaxone was administered with the ventriculoperitoneal shunt removal. The clinical course improved, but visual impairment last for 3 months following treatment.