Ju-Hsin Chia

Isolation of Salmonella enterica serotype choleraesuis resistant to ceftriaxone and ciprofloxacin

Salmonella enterica serotype choleraesuis (S choleraesuis) usually causes systemic infections in man that need antimicrobial treatment. We isolated a strain of S choleraesuis that was resistant to ceftriaxone and ciprofloxacin from a patient with sepsis. Ciprofloxacin resistance was associated with mutations in gyrA and parC, whereas the ampC gene (bla(CMY-2)), responsible for ceftriaxone resistance, was carried by a transposon-like mobile element. This element was found inserted into finQ of a potentially transmissible 140 kb plasmid, with an 8 bp direct repeat flanking the junction regions. The appearance of this resistant S choleraesuis is a serious threat to public health, and thus constant surveillance is warranted.

Development of a Multiplex PCR and SHV Melting-Curve Mutation Detection System for Detection of Some SHV and CTX-M β-Lactamases of Escherichia coli, Klebsiella pneumoniae, and Enterobacter cloacae in Taiwan

ABSTRACT Infection by extended-spectrum β-lactamase (ESBL)-producing Enterobacteriaceae has been increasing in Taiwan. Accurate identification of the ESBL genes is necessary for surveillance and for epidemiological studies of the mode of transmission in the hospital setting. We describe herein the development of a novel system, which consists of a multiplex PCR to identify blaSHV, blaCTX-M-3-like, and blaCTX-M-14-like genes and a modified SHV melting-curve mutation detection method to rapidly distinguish six prevalent blaSHV genes (blaSHV-1, blaSHV-2, blaSHV-2a, blaSHV-5, blaSHV-11, and blaSHV-12) in Taiwan. Sixty-five clinical isolates, which had been characterized by nucleotide sequencing of the blaSHV and blaCTX-M genes, were identified by the system. The system was then used to genotype the ESBLs from 199 clinical isolates, including 40 Enterobacter cloacae, 68 Escherichia coli, and 91 Klebsiella pneumoniae, collected between August 2002 and March 2003. SHV-12 (80 isolates) was the most prevalent type of ESBL identified, followed in order of frequency by CTX-M-3 (65 isolates) and CTX-M-14 (36 isolates). Seventeen (9%) of the 199 clinical isolates harbored both SHV- and CTX-M-type ESBLs. In contrast to Enterobacter cloacae, the majority of which produced SHV-type ESBLs, E. coli and K. pneumoniae were more likely to possess CTX-M-type ESBLs. Three rare CTX-M types were identified through sequencing of the blaCTX-M-3-like (CTX-M-15) and blaCTX-M-14-like (CTX-M-9 and CTX-M-13) genes. The system appears to provide an efficient differentiation of ESBLs among E. coli, K. pneumoniae, and Enterobacter cloacae in Taiwan. Moreover, the design of the system can be easily adapted for similar purposes in areas where different ESBLs are prevalent.

In Vivo Acquisition of Ceftriaxone Resistance in Salmonella enterica Serotype Anatum

ABSTRACT The emergence of resistance to antimicrobial agents within the salmonellas is a worldwide and severe problem. A case of treatment failure due to the emergence of resistance to ceftriaxone in Salmonella enterica serotype Anatum was studied. S. enterica serotype Anatum and Escherichia coli, both of which are susceptible to ceftriaxone, were initially isolated from a diabetic patient hospitalized for the treatment of wound and urinary tract infections. Resistant S. enterica serotype Anatum and E. coli strains were isolated concomitantly 2 weeks after the initiation of ceftriaxone therapy. The patient eventually died of a sepsis caused by the ceftriaxone-resistant salmonella. PCR, nucleotide sequence analysis, and DNA-DNA hybridization identified a blaCTX-M-3 gene located on a 95.1-kb plasmid from the ceftriaxone-resistant isolates of S. enterica serotype Anatum and E. coli. The plasmid was proved to be conjugative. Molecular fingerprinting showed that the susceptible and resistant strains were genetically indistinguishable. The emergence of resistance to ceftriaxone in S. enterica serotype Anatum was due to the in vivo acquisition of a plasmid containing the blaCTX-M-3 gene and was the cause for treatment failure in this patient.

Extended epidemic of nosocomial urinary tract infections caused by Serratia marcescens.

ABSTRACT In recent years a significant increase in the incidence of Serratia marcescens infections was noted at the Chang Gung Memorial Hospital, Taoyuan, Taiwan. A review of laboratory (1991 to 2002) and infection control (1995 to 2002) records showed the possibility of an extended epidemic of nosocomial urinary tract infections (UTIs) caused by S. marcescens. Therefore, in 1998 and 1999, 87 isolates were collected from patients with such infections and examined and another 51 isolates were collected in 2001 and 2002. The patients were mostly elderly or the infections were associated with the use of several invasive devices. S. marcescens was usually the only pathogen found in urine cultures in our study. Neither prior infections nor disseminated infections with the organism were observed in these patients. Resistance to most antibiotics except imipenem was noted. Two genotyping methods, pulsed-field gel electrophoresis and infrequent-restriction-site PCR, were used to examine the isolates. A total of 12 genotypes were identified, and 2 predominant genotypes were found in 72 (82.8%) of the 87 isolates derived from all over the hospital. However, 63.9% of the isolates of the two genotypes were from neurology wards. A subsequent intervention by infection control personnel reduced the infection rate greatly. The number and proportion of the two predominant genotypes were significantly reduced among the 51 isolates collected in 2001 and 2002. Thus, a chronic and long-lasting epidemic of nosocomial UTIs caused by S. marcescens was identified and a successful intervention was carried out. Both a cautious review of laboratory and infection control data and an efficient genotyping system are necessary to identify such a cryptic epidemic and further contribute to the quality of patient care.

Influence of teicoplanin MICs on treatment outcomes among patients with teicoplanin-treated methicillin-resistant Staphylococcus aureus bacteraemia: a hospital-based retrospective study

OBJECTIVES Higher vancomycin MIC values (≥1.5 mg/L via Etest) may be associated with vancomycin treatment failure among patients with serious methicillin-resistant Staphylococcus aureus (MRSA) infections. As there were limited similar data for teicoplanin, this retrospective cohort study intended to determine the predictive value of teicoplanin MICs for treatment failure among patients with MRSA bacteraemia. PATIENTS AND METHODS All patients with at least one blood culture positive for MRSA admitted to the hospital between January 2010 and January 2011 were reviewed. Patients with an age ≥18 years and receipt of teicoplanin therapy throughout the course or receipt of <72 h of vancomycin therapy and then teicoplanin for >3 days were enrolled. Teicoplanin Etest(®) MICs and treatment outcomes for MRSA bacteraemia were reviewed to identify the breakpoint of teicoplanin MICs influencing treatment outcomes. RESULTS Of the 101 patients enrolled, 56 had a lower teicoplanin MIC (≤1.5 mg/L) for MRSA and 45 had a higher MIC (>1.5 mg/L) for MRSA. A lower teicoplanin MIC was associated with a favourable outcome [37 (66.1%) versus 13 (28.9%); P<0.001] and a lower rate of bloodstream infection-related mortality [15 (26.8%) versus 22 (48.9%); P=0.022]. Patients with chronic obstructive pulmonary disease, bacteraemic pneumonia or higher Pittsburgh bacteraemia score had an unfavourable outcome (P=0.028, 0.022 and <0.001, respectively). Multivariate analysis showed that teicoplanin MIC >1.5 mg/L, higher Pittsburgh bacteraemia score and bacteraemic pneumonia were independent risk factors for unfavourable outcome. CONCLUSIONS A higher teicoplanin MIC value (>1.5 mg/L) may predict an unfavourable outcome and higher mortality rate among teicoplanin-treated MRSA bacteraemic patients.

Secular trends in incidence and antimicrobial resistance among clinical isolates of salmonella at a university hospital in Taiwan, 1983-1999

The incidence and antimicrobial resistance among clinical isolates of salmonella at a university hospital in Taiwan between 1983 and 1999 are summarized in this report. A total of 7986 isolates were analysed. Serogroup B has been the most prevalent over the years, with an apparently continuous decline after 1995. Concordant decrease was also found among S. choleraesuis and S. typhi isolates in recent years. In contrast, the proportion of serogroup D strains increased significantly after 1996. S. typhi remained relatively susceptible to most of the antimicrobial agents examined. For non-typhoidal isolates, antimicrobial resistance to ampicillin (62%), chloramphenicol (67%), and sulfamethoxazole-trimethoprim (37%) was relatively higher than that reported elsewhere. Newer generation cephalosporins and fluoroquinolones remained effective over the years, although emerging resistance to these drugs has been noticed since 1992. A more prudent selection and use of antimicrobial agents, in both humans and animals, and a continuous surveillance of resistance are essential in the future.

Risk factors and outcomes of carbapenem-nonsusceptible Escherichia coli bacteremia: A matched case–control study

BACKGROUND Infections due to carbapenem-resistant Enterobacteriaceae have been the emerging problem worldwide. This primary object of this study was to understand the risk factors and clinical outcomes of carbapenem-nonsusceptible Escherichia coli (CNSEc) bacteremia. METHODS We conducted a matched case-control study in a 3,715-bed tertiary care medical center in northern Taiwan. The controls were selected among patients with carbapenem-susceptible E coli and were matched with CNSEc for bacteremia. RESULTS Fifty-one patients were included in this study (17 cases and 34 controls). Bivariate analysis showed that prior exposure to carbapenems (p<0.001), stay in intensive care units (p=0.016), placement of central venous catheters (p=0.001), chronic liver diseases (p<0.001), uremia with regular dialysis (p=0.004), and mechanical ventilation (p=0.004) were associated with CNSEc bacteremia. Multivariate analysis revealed that prior exposure to carbapenems [odds ratio (OR), 29.17; 95% confidence interval (CI), 1.76-484.70; p=0.019], uremia with regular dialysis (OR, 98.58; 95% CI, 4.02-999; p=0.005) and chronic liver diseases (OR, 27.86; 95% CI, 2.31-335.83; p=0.009) were independent risk factors for CNSEc bacteremia. Compared with carbapenem-susceptible E coli group, CNSEc group had a longer hospital stay (68.4 days vs. 35.8 days; p=0.04) and a higher disease severity, as indicated by a Pittsburgh bacteremia score greater than or equal to 4 (5.6% vs. 2.5%; p=0.015). Patients with CNSEc bacteremia had a higher overall in-hospital mortality rate (94.12% vs. 50.00%; p=0.002), but there was no difference in the 28-day mortality between these two groups. CONCLUSIONS CNSEc bacteremia would lead to a poor outcome among patients with prior exposure to carbapenems, chronic liver disease, and uremia with regular dialysis.

Dissemination of Extended-Spectrum β-Lactamase-Producing Enterobacteriaceae in Pediatric Intensive Care Units

ABSTRACT To study the growing trend of extended-spectrum β-lactamase (ESBL)-producing Enterobacteriaceae in pediatric intensive care units (PICUs), 88 nonrepetitive ESBL-producing isolates were prospectively collected and analyzed by molecular methods during a 16-month period. The emergence and dissemination of ESBL-producing Enterobacteriaceae in PICUs are the consequence of the clonal dissemination of a few epidemic strains along with the horizontal transmission of resistance gene-carrying plasmids among bacterial organisms.

NK cells kill mycobacteria directly by releasing perforin and granulysin

Although the mechanisms underlying the cytotoxic effect of NK cells on tumor cells and intracellular bacteria have been studied extensively, it remains unclear how these cells kill extracellular bacterial pathogens. In this study, we examine how human NK cells kill Mycobacterium kansasii and M.tb. The underlying mechanism is contact dependent and requires two cytolytic proteins: perforin and granulysin. Mycobacteria induce enhanced expression of the cytolytic proteins via activation of the NKG2D/NCR cell‐surface receptors and intracellular signaling pathways involving ERK, JNK, and p38 MAPKs. These results suggest that NK cells use similar cellular mechanisms to kill both bacterial pathogens and target host cells. This report reveals a novel role for NK cells, perforin, and granulysin in killing mycobacteria and highlights a potential alternative defense mechanism that the immune system can use against mycobacterial infection.

Outcomes and characteristics of ertapenem-nonsusceptible Klebsiella pneumoniae bacteremia at a university hospital in Northern Taiwan: A matched case-control study

BACKGROUND AND PURPOSE Carbapenem-resistant Klebsiella pneumoniae is an emerging problem worldwide. The object of this study was to investigate the risk factors, characteristics and outcomes of ertapenem-nonsusceptible K pneumoniae (ENSKp) bacteremia. METHODS We conducted a 1:2 ratio matched case-control study. The controls were randomly selected among patients with ertapenem-susceptible K pneumoniae (ESKp) bacteremia and were matched with ENSKp cases for bacteremia. RESULTS Seventy-five patients were included in this study (25 cases and 50 controls). Bivariate analysis showed that prior exposure to either β-Lactam/β-Lactam-lactamase inhibitors (p = 0.008) or 4(th) generation cephalosporins (p < 0.001), chronic obstructive pulmonary disease (COPD) (p = 0.001), acute renal failure (p = 0.021), chronic kidney disease without dialysis (p = 0.021), recent hospital stay (p = 0.016), intensive care unit stay (p = 0.002), mechanical ventilation (p = 0.003), central venous catheter placement (p = 0.016), Foley indwelling (p = 0.022), polymicrobial bacteremia (p = 0.003) and higher Pittsburgh bacteremia score (p < 0.001) were associated with ENSKp bacteremia. The multivariate analysis showed that prior exposure to 4(th) generation cephalosporins (odds ratio [OR], 28.05; 95% confidence interval [CI], 2.92-269.85; p = 0.004), COPD (OR, 21.38; 95% CI, 2.95-154.92; p = 0.002) and higher Pittsburgh bacteremia score (OR, 1.35; 95% CI, 1.10-1.66; p = 0.004) were independent factors for ENSKp bacteremia. ENSKp bacteremia had a higher 14-day mortality rate than ESKp bacteremia (44.0% vs. 22.0%; p = 0.049). The overall in-hospital mortality rates for these two groups were 60.0% and 40.0% respectively (p = 0.102). CONCLUSION ENSKp bacteremia had a poor outcome and the risk factors were prior exposure of 4(th) generation cephalosporins, COPD and higher Pittsburgh bacteremia score. Antibiotic stewardship may be the solution for the preventive strategy.