Jang-Jih Lu

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.

Molecular epidemiology and evolutionary genetics of Mycobacterium tuberculosis in Taipei

BackgroundThe control of tuberculosis in densely populated cities is complicated by close human-to-human contacts and potential transmission of pathogens from multiple sources. We conducted a molecular epidemiologic analysis of 356 Mycobacterium tuberculosis (MTB) isolates from patients presenting pulmonary tuberculosis in metropolitan Taipei. Classical antibiogram studies and genetic characterization, using mycobacterial interspersed repetitive-unit-variable-number tandem-repeat (MIRU-VNTR) typing and spoligotyping, were applied after culture.MethodsA total of 356 isolates were genotyped by standard spoligotyping and the strains were compared with in the international spoligotyping database (SpolDB4). All isolates were also categorized using the 15 loci MIRU-VNTR typing method and combin with NTF locus and RD deletion analyses.ResultsOf 356 isolates spoligotyped, 290 (81.4%) displayed known spoligotypes and 66 were not identified in the database. Major spoligotypes found were Beijing lineages (52.5%), followed by Haarlem lineages (13.5%) and EAI plus EAI-like lineages (11%). When MIRU-VNTR was employed, 140 patterns were identified, including 36 clusters by 252 isolates and 104 unique patterns, and the largest cluster comprised 95 isolates from the Beijing family. The combination of spoligotyping and MIRU-VNTR revealed that 236 (67%) of the 356 isolates were clustered in 43 genotypes. Strains of the Beijing family was more likely to be of modern strain and a higher percentage of multiple drug resistance than other families combined (P = 0.08). Patients infected with Beijing strains were younger than those with other strains (mean 58.7 vs. 64.2, p = 0.02). Moreover, 85.3% of infected persons younger than 25 years had Beijing modern strain, suggesting a possible recent spread in the young population by this family of TB strain in Taipei.ConclusionOur data on MTB genotype in Taipei suggest that MTB infection has not been optimally controlled. Control efforts should be reinforced in view of the high prevalence of the Beijing strain in young population and association with drug resistance.

Experience of using convalescent plasma for severe acute respiratory syndrome among healthcare workers in a Taiwan hospital

Abstract Objectives: To describe the immunological responses and clinical outcome of coronavirus (SARS) infected healthcare workers (HCW) who had been administered with convalescent plasma as a treatment. Methods: Convalescent plasma (500 mL) was obtained from each of three SARS patients and transfused into the three infected HCW. Donors were blood type O and seronegative for hepatitis B and C, HIV, syphilis and human T-cell lymphotropic virus types I and II (HTLV-I and -II). Serum antibody (IgG) titre was >640. Apharesis was performed with a CS 3000 plus cell separator followed by the forming of the convalescent phase plasma. As part of the routine check with donated plasma, the convalescent plasma was confirmed free of residual SARS-CoV by RT–PCR. Serial serum samples obtained from the recipients of the convalescent plasma were collected to undertake real-time quantitative RT–PCR for SARS-CoV for direct measurement of viral concentration. Specific immunoglobulin IgM and IgG concentrations were titrated using an antigen microarray developed in-house. Results: Viral load dropped from 495 × 103, 76 × 103 or 650 × 103 copies/mL to zero or 1 copy/mL one day after transfusion. Anti-SARS-CoV IgM and IgG also increased in a time-dependent manner following transfusion. All three patients survived. One HCW became pregnant subsequently, delivering 13 months after discharge. Positive anti-SARS-CoV IgG was detected in the newborn. Passive transfer of anti-SARS-CoV antibody from the mother was considered as a possibility. Conclusions: All infected HCW whose condition had progressed severely and who had failed to respond to the available treatment, survived after transfusion with convalescent plasma.

Molecular typing and phenotype characterization of methicillin-resistant Staphylococcus aureus isolates from blood in Taiwan.

Background Staphylococcus aureus causes a variety of severe infections such as bacteremia and sepsis. At present, 60–80% of S. aureus isolates from Taiwan are methicillin resistant (MRSA). It has been shown that certain MRSA clones circulate worldwide. The goals of this study were to identify MRSA clones in Taiwan and to correlate the molecular types of isolates with their phenotypes. Methods A total of 157 MRSA isolates from bacteremic patients were collected from nine medical centers. They were typed based on polymorphisms in agr, SCCmec, MLST, spa, and dru. Phenotypes characterized included Panton-Valentine leucocidin (pvl), inducible macrolide-lincosamide-streptogramin B resistance (MLSBi), vancomycin (VA) and daptomycin (DAP) minimal inhibitory concentrations (MIC), and superantigenic toxin gene profiles. Difference between two consecutive samples was determined by Mann-Whitney-U test, and difference between two categorical variables was determined by Fishers exact test. Results Four major MRSA clone complexes CC1, CC5, CC8, and CC59 were found, including 4 CC1, 9 CC5, 111 CC8, and 28 CC59 isolates. These clones had the following molecular types: CC1: SCCmecIV and ST573; CC5: SCCmecII and ST5; CC8: SCCmecIII, ST239, and ST241, and CC59: SCCmecIV, SCCmecVT, ST59, and ST338. The toxin gene profiles of these clones were CC1: sec-seg-(sei)-sell-selm-(seln)-selo; CC5: sec-seg-sei-sell-selm-(seln)-selp-tst1; CC8: sea-selk-selq, and CC59: seb-selk-selq. Most isolates with SCCmecVT, ST59, spat437, and dru11 types were pvl + (13 isolates), while multidrug resistance (≥4 antimicrobials) were associated with SCCmecIII, ST239, spa t037, agrI, and dru14 (119 isolates) (p<0.001). One hundred and twenty four isolates with the following molecular types had higher VA MIC: SCCmecII and SCCmecIII; ST5, ST239, and ST241; spa t002, t037, and t421; dru4, dru10, dru12, dru13, and dru14 (p<0.05). No particular molecular types were found to be associated with MLSBi phenotype. Conclusions Four major MRSA clone complexes were found in Taiwan. Further studies are needed to delineate the evolution of MRSA isolates.

In vitro activity of nemonoxacin (TG-873870), a novel non-fluorinated quinolone, against clinical isolates of Staphylococcus aureus, enterococci and Streptococcus pneumoniae with various resistance phenotypes in Taiwan

OBJECTIVES The aim of this study was to assess the in vitro activities of nemonoxacin against Gram-positive cocci with various resistance phenotypes. METHODS MICs of nemonoxacin were determined for 798 recently collected (2005-07) and non-duplicate isolates of Gram-positive cocci by the agar dilution method. These isolates included: methicillin-susceptible Staphylococcus aureus (MSSA; n = 100); methicillin-resistant S. aureus (MRSA), including ciprofloxacin-susceptible (n = 50), ciprofloxacin-resistant (n = 100), vancomycin-intermediate (n = 50) and daptomycin-non-susceptible (DNS-MRSA; n = 5) isolates, and community-acquired MRSA (CA-MRSA; n = 101); invasive Streptococcus pneumoniae isolates (n = 150); levofloxacin-non-susceptible (MICs of 4-64 mg/L) S. pneumoniae isolates (n = 30); and enterococci (n = 212), including vancomycin-resistant enterococci (VRE; n = 112). RESULTS Nemonoxacin had potent activity against MSSA (MIC(90) of < or =0.03 mg/L), ciprofloxacin-susceptible MRSA (MIC(90) of < or =0.03 mg/L) and CA-MRSA (MIC(90) of 0.06 mg/L). For all invasive S. pneumoniae isolates, the activity of nemonoxacin (MIC(90) of 0.06 mg/L) was similar to that of gemifloxacin and much better than that of levofloxacin (MIC(90) of 2 mg/L) and moxifloxacin (MIC(90) of 0.25 mg/L). Nemonoxacin had a 32- to 64-fold higher activity than levofloxacin against levofloxacin-non-susceptible isolates. Nemonoxacin exerted limited activity against ciprofloxacin-resistant MRSA (MIC(90) of 1 mg/L), vancomycin-intermediate MRSA (MIC(90) of 2 mg/L), DNS-MRSA (MIC(90) of 1 mg/L), vancomycin-susceptible enterococci (MIC(90) of 2 mg/L for Enterococcus faecalis and 4 mg/L for Enterococcus faecium) and VRE (MIC(90) of 4 mg/L for E. faecalis and 16 mg/L for E. faecium). CONCLUSIONS Our findings point to a potentially useful role for nemonoxacin in the treatment of infections caused by MSSA, ciprofloxacin-susceptible MRSA and S. pneumoniae with various resistance phenotypes.

Characterizations of Clinical Isolates of Clostridium difficile by Toxin Genotypes and by Susceptibility to 12 Antimicrobial Agents, Including Fidaxomicin (OPT-80) and Rifaximin: a Multicenter Study in Taiwan

ABSTRACT A total of 403 nonduplicate isolates of Clostridium difficile were collected at three major teaching hospitals representing northern, central, and southern Taiwan from January 2005 to December 2010. Of these 403 isolates, 170 (42.2%) were presumed to be nontoxigenic due to the absence of genes for toxins A or B or binary toxin. The remaining 233 (57.8%) isolates carried toxin A and B genes, and 39 (16.7%) of these also had binary toxin genes. The MIC90 of all isolates for fidaxomicin and rifaximin was 0.5 μg/ml (range, ≤0.015 to 0.5 μg/ml) and >128 μg/ml (range, ≤0.015 to >128 μg/ml), respectively. All isolates were susceptible to metronidazole (MIC90 of 0.5 μg/ml; range, ≤0.03 to 4 μg/ml). Two isolates had reduced susceptibility to vancomycin (MICs, 4 μg/ml). Only 13.6% of isolates were susceptible to clindamycin (MIC of ≤2 μg/ml). Nonsusceptibility to moxifloxacin (n = 81, 20.1%) was accompanied by single or multiple mutations in gyrA and gyrB genes in all but eight moxifloxacin-nonsusceptible isolates. Two previously unreported gyrB mutations might independently confer resistance (MIC, 16 μg/ml), Ser416 to Ala and Glu466 to Lys. Moxifloxacin-resistant isolates were cross-resistant to ciprofloxacin and levofloxacin, but some moxifloxacin-nonsusceptible isolates remained susceptible to gemifloxacin or nemonoxacin at 0.5 μg/ml. This study found the diversity of toxigenic and nontoxigenic strains of C. difficile in the health care setting in Taiwan. All isolates tested were susceptible to metronidazole and vancomycin. Fidaxomicin exhibited potent in vitro activity against all isolates tested, while the more than 10% of Taiwanese isolates with rifaximin MICs of ≥128 μg/ml raises concerns.

Fluconazole-resistant Kodamaea ohmeri fungemia associated with cellulitis: Case report and review of the literature

Kodamaea (Pichia) ohmeri was formerly considered a contaminant, but is now known to be a significant human pathogen that has been shown to cause fungemia, endocarditis, funguria, and peritonitis in immunocompromised patients. We report a case of fungemia caused by K. ohmeri in a 71-year-old man with cellulitis. The patient was sent to the emergency room due to leg edema, fever, and change of consciousness. During hospitalization, a series of examinations including blood cultures were performed. On hospital day 8, blood culture yielded a yeast colony. Fluconazole was given empirically, but had no effect. The pathogen was identified as K. ohmeri by Vitek YBC card, API 20C, sequencing of the 18S rRNA gene, and the D1/D2 domains of the 26S rRNA gene and the internally transcribed spacer (ITS) regions. Antifungal susceptibility testing was performed with the ATB-Fungus system, and a high minimum inhibitory concentration (level up to 64 mg/l) for fluconazole was found. Fluconazole was replaced with amphotericin B deoxylate, and the fever and cellulitis inflammation gradually subsided. The patient was discharged in a stable condition. This is the first case of K. ohmeri fungemia in Taiwan.

Detection and typing of vancomycin-resistance genes of enterococci from clinical and nosocomial surveillance specimens by multiplex PCR

Ninety-three clinical isolates of vancomycin-resistant enterococci (VRE) collected from nine hospitals in Taiwan were examined for the presence of vanA, vanB, vanC1, or vanC2/vanC3 genes by a multiplex PCR. Forty-seven of these VRE isolates were vanA positive, 1 contained both vanC1 and vanA, 40 harboured vanB, 2 were vanC1, and 3 were identified to be vanC2/vanC3. Twenty-four vanA isolates were sensitive to teicoplanin and thus did not have a typical VanA phenotype. Five isolates with the VanC phenotype harboured vanB. None of the 40 clinically isolated vancomycin-susceptible E. faecium or E. faecalis and the vancomycin-resistant Leuconostoc and Pediococcus isolates were positive for any of the van genes. While performing nosocomial surveillance, VRE were isolated from 47 of 467 rectal swabs by culture. Compared with the conventional culture method, the sensitivity and specificity of the multiplex PCR for detecting and identifying vancomycin-resistance genes in enterococci directly from culture-positive broth were 97.9% and 100%, respectively. The results suggest that genotypic characterization of vancomycin-resistance is necessary for all clinical VRE isolates and that the multiplex PCR assay can be an alternative method for this purpose.

High Prevalence of VanB2 Vancomycin-Resistant Enterococcus faecium in Taiwan

ABSTRACT Thirty-six VanB glycopeptide-resistant Enterococcus faecium isolates were collected from patients in five different hospitals in Taiwan. The vancomycin resistance genes were amplified by the long vanB PCR, which amplifies the 6,373-bpvanB gene cluster including thevanRB2, vanSB2, vanYB2, vanWB2, vanHB2, vanB2, andvanXB2 genes. The deduced amino acid sequences were found to be 95 to 98% homologous to those of thevanB1 gene cluster: VanRB1, 97%; VanSB1, 97%; VanYB1, 96%; VanHB1, 95%; VanB1, 96%; and VanXB1, 98%. Restriction enzyme analysis of the long vanB PCR products revealed that all 36 isolates had the same vanB2-specific pattern. DNA sequence analysis of the vanB2 gene, which is ad-Ala–d-Lac ligase gene, revealed that none of the 36 sequences were identical to the previously publishedvanB2 sequence. Thirty-one isolates had 1 nucleotide different from the published vanB2 sequence. The sequences of the other five isolates differed from the publishedvanB2 sequence by 2 or 3 nucleotides. Four isolates with a low or moderate resistance to vancomycin (MIC = 4 to 32 μg/ml) were found to have the same leucine-to-methionine change at amino acid position 308 of the vanB2 gene. The genomic DNAs of all 36 isolates were digested with SmaI and then typed by pulsed-field gel electrophoresis (PFGE). Eight different PFGE types (I to VIII) were observed, and type I was found to be prevalent in all hospitals examined in this study. This result suggests that intra- and interhospital dissemination of this E. faecium strain has occurred in Taiwan.

Changing trends in antimicrobial resistance of major bacterial pathogens, 1985–2005: A study from a medical center in northern Taiwan

BACKGROUND Antimicrobial resistance is a major health problem worldwide. We evaluated the antimicrobial resistance trends of 16 major bacterial pathogens at a tertiary medical center in northern Taiwan. METHODS We conducted a retrospective review of annual summary documents for antimicrobial susceptibility of clinically isolated gram-positive and gram-negative bacteria from 1985 to 2005. The numbers of isolates and susceptibilities were calculated for three 7-year periods: first period, 1985-1991; second period, 1992-1998; and the third period, 1999-2005. RESULTS During the 21-year period, 219,715 bacterial pathogens were identified. A significant increase in incidence over time was found for methicillin-resistant Staphylococcus aureus, methicillin-resistant S epidermidis, penicillin-nonsusceptible Streptococcus pneumoniae, erythromycin-resistant S pneumoniae, vancomycin-resistant enterococci, cefotaxime/ceftriaxone-resistant Escherichia coli and Klebsiella pneumoniae, and imipenem-resistant Acinetobacter baumannii. Additionally, a significant increase in ciprofloxacin resistance rates over time from 1996 to 2005 was noted for E coli, Enterobacter cloacae, and A baumannii (through 1997 to 2005). However, a significant decrease in erythromycin resistance rate with time from 1999 to 2005 was found for Groups A and B streptococci, non-A, B, D streptococci, and S pneumoniae. CONCLUSION Resistance to antimicrobial agents increased rapidly in the past two decades in Taiwan and has become very common in major bacterial pathogens. Continuous enforcement of policies to limit use of antimicrobial agents and active surveillance of antimicrobial resistance through a nationwide system are both warranted.