Yu-Chi Chen

Nosocomial Infections Caused by Sphingomonas paucimobilis: Clinical Features and Microbiological Characteristics

From January 1995 to September 1996, 14 isolates of Sphingomonas paucimobilis, including 11 from clinical specimens from six patients with nosocomial infection and three from environmental sources, were collected. Two of the six patients had intravascular catheter-related bacteremia and one each had bacteremic biliary tract infection, urinary tract infection, ventilator-associated pneumonia, and wound infection. The S. paucimobilis isolates were identified according to biochemical profiles established with use of the API 20NE system and Vitek GNI card and the characteristic cellular fatty acid chromatogram. Ten biotypes, 11 antibiograms (by the Etest), and 12 random amplified polymorphic DNA (RAPD) patterns (by arbitrarily primed polymerase chain reaction) were identified. The identical biotype, antibiogram, and RAPD pattern of the two isolates (one each from blood and bile) from a patient with biliary tract infection indicated the invasiveness of the organism. Two patients with intravascular catheter-related bacteremia had isolates of this organism repeatedly recovered, and these isolates had heterogeneous RAPD patterns. The present study highlights the wide distribution in hospital environments of various clones of S. paucimobilis, which may cause recurrent infections by a single strain or several episodes of infection due to two or more clones of this organism in hospitalized patients.

Quinupristin-Dalfopristin Resistance among Gram-Positive Bacteria in Taiwan

ABSTRACT To understand quinupristin-dalfopristin resistance among clinical isolates of gram-positive bacteria in Taiwan, where this agent is not yet available for clinical use, we evaluated 1,287 nonduplicate isolates recovered from January 1996 to December 1999 for in vitro susceptibility to quinupristin-dalfopristin and other newer antimicrobial agents. All methicillin-susceptible Staphylococcus aureus (MSSA) isolates were susceptible to quinupristin-dalfopristin. High rates of nonsusceptibility to quinupristin-dalfopristin (MICs, ≥2 μg/ml) were demonstrated for the following organisms: methicillin-resistant S. aureus (MRSA) (31%), coagulase-negative staphylococci (CoNS) (16%),Streptococcus pneumoniae (8%), viridans group streptococci (51%), vancomycin-susceptible enterococci (85%), vancomycin-resistantEnterococcus faecalis (100%), vancomycin-resistantEnterococcus faecium (66%), Leuconostoc spp. (100%), Lactobacillus spp. (50%), andPediococcus spp. (87%). All isolates of MSSA, MRSA,S. pneumoniae, and viridans group streptococci were susceptible to vancomycin and teicoplanin. The rates of nonsusceptibility to vancomycin and teicoplanin were 5 and 7%, respectively, for CoNS, ranging from 12 and 18% for S. simulans to 0 and 0% for S. cohnii and S. auricularis. Moxifloxacin and trovafloxacin had good activities against these isolates except for ciprofloxacin-resistant vancomycin-resistant enterococci and methicillin-resistant staphylococci. In Taiwan, virginiamycin has been used in animal husbandry for more than 20 years, which may contribute to the high rates of quinupristin-dalfopristin resistance.

Nutritionally Variant Streptococcal Infections at a University Hospital in Taiwan: Disease Emergence and High Prevalence of β-Lactam and Macrolide Resistance

From January 1993 to December 2002, 28 patients with nutritionally variant streptococci (NVS) infections were treated at a university hospital in Taiwan. Twelve (43%) of these patients had various underlying malignancies, and 7 (25%) had underlying valvular heart diseases. Nine patients (32%) had infective endocarditis, and 9 (32%) had primary bacteremia. The deaths of 7 patients (25%) were directly related to NVS infection. Among the 28 isolates recovered from these patients, 50% were not susceptible to penicillin, 33% were not susceptible to cefotaxime, and 93% were not susceptible to azithromycin.

Indwelling Device-Related and Recurrent Infections Due to Aeromonas Species

From October 1995 to February 1997, 13 isolates of Aeromonas species were recovered from four patients treated at National Taiwan University Hospital (Taipei). One of the patients, a diabetic, had simultaneous Aeromonas veronii biotype veronii bacteremia and A. veronii biotype sobria urinary tract infection. Seven weeks after the episode, the patient had necrotizing fasciitis due to A. veronii biotype veronii. The other three patients all had underlying hepatobiliary malignancies complicated by obstructive jaundice, and all underwent percutaneous transhepatic cholangiographic drainage. These three patients had multiple isolates of Aeromonas species (A. hydrophila and/or A. caviae) recovered from samples of blood or bile or from catheter insertion sites. All isolates were identified on the basis of the results of extended biochemical tests as well as characteristic cellular fatty acid profiles. The results of genotyping generated by arbitrarily primed polymerase chain reaction and of susceptibility testing showed that these Aeromonas species were pathogens that caused indwelling device-related infections and that the organisms could persist for long periods, with subsequent recurrence of severe infection. Concomitant infection due to more than one Aeromonas species or caused by polyclonal A. hydrophila or A. veronii biotype veronii was also documented.