Chun-Ming Lee

Emergence and spread of multi-drug resistant organisms: Think globally and act locally

Centers for Disease Control, Department of Health, Taiwan, ROC Division of Infectious Diseases, Department of Internal Medicine, Mackay Memorial Hospital, Taiwan, ROC Division of Pediatric Infectious Diseases, Department of Pediatrics, Chang Gung Memorial Hospital and College of Medicine, Chang Gung University, Taiwan, ROC Department of Internal Medicine, National Taiwan University Hospital and National Taiwan University College of Medicine, Taiwan, ROC Department of Internal Medicine, National Defense Medical Center, Taiwan, ROC

Impact of susceptibility profiles of Gram-negative bacteria before and after the introduction of ertapenem at a medical center in northern Taiwan from 2004 to 2010 ☆ ☆☆ ★

This retrospective observational study evaluated the impact of antimicrobial consumption on antimicrobial susceptibility among aerobic Gram-negative bacteria after introducing ertapenem to the formulary of a teaching hospital (1130 beds) in northern Taiwan. Data on consumption of various antimicrobial agents, expressed as defined daily dose/1000 patient-days (DDD/1000 PD), were collected retrospectively from hospital pharmacy records 2 years before and 5 years after the introduction of ertapenem (October 2005). During the study period, the consumption of ampicillin and aminoglycosides decreased significantly. In contrast, the consumption of cefoxitin, ceftazidime, cefpirome, piperacillin-tazobactam, carbapenems (ertapenem, imipenem, and meropenem), and fluoroquinolones (ciprofloxacin, levofloxacin, and moxifloxacin) increased significantly over time. There was a significant increase in the rate of susceptibility of Escherichia coli to ampicillin, cefotaxime, ceftazidime, piperacillin-tazobactam, cefpirome, amikacin, and levofloxacin; an increase in the rate of susceptibility of Klebsiella pneumoniae to ceftazidime, cefepime, cefpirome, piperacillin-tazobactam, meropenem, levofloxacin, and amikacin; a significant decrease in the rate of susceptibility of Pseudomonas aeruginosa to meropenem; and a significant decrease in the rate of susceptibility of Acinetobacter baumannii to ceftazidime, carbapenems, ciprofloxacin, and levofloxacin. The rate of antibiotic susceptibility to ertapenem of extended spectrum β-lactamase producers, including E. coli and K. pneumoniae, remained stable. Usage of ertapenem was found to be negatively and significantly associated with the susceptibility rates of P. aeruginosa to meropenem and gentamicin. Significantly negative correlations were noted between the use of ertapenem and the rates of susceptibility of A. baumannii to ceftazidime, piperacillin-tazobactam, carbapenems (imipenem and meropenem), ciprofloxacin, and levofloxacin.

Antimicrobial susceptibility and clinical outcomes of Candida parapsilosis bloodstream infections in a tertiary teaching hospital in Northern Taiwan

BACKGROUND Candida parapsilosis is an emerging non-albicans Candida that is associated with central line-associated infection. C. parapsilosis has higher minimal inhibitory concentration to echinocandin than Candida albicans, and the effects of echinocandin on C. parapsilosis are ambiguous. Therefore, in this study, we aimed to investigate the susceptibility and the correlation between incidence and drug consumption. METHODS This retrospective study was conducted in a tertiary teaching hospital in northern Taiwan between 2008 and 2012. The Candida species distribution, the correlation between the use of antifungal agents and the incidence of C. parapsilosis bloodstream infection, demographic information, clinical characteristics, mortality rate, and in vitro susceptibility of C. parapsilosis were analyzed. RESULTS A total of 77 episodes from 77 patients were included for analysis. The overall 90-day mortality rate was 41.6%. The incidence of C. parapsilosis bloodstream infection showed a moderate positive correlation with the increased defined daily dose of echinocandin. The risk factors associated with mortality included malignancy or a metastatic tumor. Multivariate logistical regression analysis showed that patients with malignancy had higher odds ratios in terms of mortality. The rate of C. parapsilosis resistance to fluconazole was 3%, whereas the susceptibility rate was 95.5%. CONCLUSION Underlying comorbidity and malignancy were factors leading to death in patients with C. parapsilosis bloodstream infection. Catheter removal did not influence the mortality rate. The survival rate of patients receiving echinocandin was lower than the group receiving fluconazole. Fluconazole remains the drug of choice to treat C. parapsilosis bloodstream infections.

Citrobacter freundii bacteremia: Risk factors of mortality and prevalence of resistance genes

BACKGROUND/PURPOSE Multidrug-resistant strains of Citrobacter have emerged, which carry Amp-C β-lactamase (Amp-C), broad-spectrum β-lactamase, extended-spectrum β-lactamase (ESBL), and other resistance mechanisms. These strains are associated with a higher rate of in-hospital mortality. The object of this study is to determine the mortality risk factors, susceptibility pattern to antibiotics, and prevalence of resistance genes in patients with Citrobacter freundii bacteremia. METHODS From January 2009 to December 2014, blood isolates of C. freundii were collected in MacKay Memorial Hospital, Taipei, Taiwan. PCR technique and sequencing were performed for resistance genes. Pulsed-field gel electrophoresis (PFGE) was done using XbaI restriction enzyme. The clinical characteristics and risk factors for mortality are demonstrated. RESULTS The 36 blood isolates of C. freundii belonged to 32 different PFGE pulsotypes, and 15 isolates (41.7%) were polymicrobial. The most common source of infection was intra-abdominal origin (61.1%), followed by unknown sources (22.2%), the urinary tract (8.3%), intravascular catheter (5.6%), and soft tissue (2.8%). High degree of antibiotic resistance was noted for cefazolin (100%), cefoxitin (97.2%), and cefuroxime (66.7%). The blaTEM-1 resistance gene was present in 16.7% isolates. 72.2% isolates carried blaAmpC and 5.6% isolates carried ESBL genes (blaSHV-12 or blaCTX-M-15). Multivariate analysis indicated that the independent risk factor for 28-day mortality was carrying the blaTEM-1 resistance gene. CONCLUSION For patients with C. freundii bacteremia, carrying the blaTEM-1 resistance gene was an independent risk factor for 28-day mortality. Carbapenems, fourth-generation cephalosporins, amikacin, and quinolones are still reliable agents for drug-resistant strains.

Trend in vancomycin susceptibility and correlation with molecular characteristics of methicillin-resistant Staphylococcus aureus causing invasive infections in Taiwan: results from the Tigecycline in vitro Surveillance in Taiwan (TIST) study, 2006-2010.

This study was intended to investigate the trend in vancomycin susceptibility and correlation with molecular characteristics of methicillin-resistant Staphylococcus aureus (MRSA) causing invasive infections. A total of 670 MRSA isolates were collected from patients with invasive infections as part of bacterial collection in the Tigecycline in vitro Surveillance in Taiwan (TIST) from 2006 to 2010. MICs of the isolates to vancomycin were determined using the agar dilution method. Characteristics of staphylococcal cassette chromosome mec (SCCmec), mec-associated hypervariable region (dru), and accessory gene regulator (agr) of the isolates were identified by polymerase chain reaction methods. MRSA isolates with SCCmec types I, II, and III were molecularly defined as hospital-associated MRSA (HA-MRSA), and those with SCCmec types IV, V, and VT were assigned as community-associated MRSA (CA-MRSA). All but 1 MRSA isolates exhibited vancomycin MICs ≤1 mg/L. A declining trend in vancomycin MICs among MRSA isolates was noted, which was associated with the decline in proportion of HA-MRSA. The percentage of CA-MRSA increased from 25.6% in 2006 to 46.0% in 2010. An increase in the geometric mean of vancomycin MICs was found in MRSA with particular molecular types such as SCCmec types II and III, agr groups I and II, and dru10-14. A significant correlation among particular molecular types was found, including SCCmecII-agr group II-dru4, SCCmecIII-agr group I-dru11-14, SCCmecIV-agr group II-dru9, and SCCmecVT-agr group I-dru9 and dru11. There was no vancomycin creep among MRSA isolates, and the declining trend of vancomycin MIC against MRSA was attributed to the increasing prevalence of CA-MRSA over time.

Primary Brain Abscess Due to Nocardia Otitidiscaviarum: A Case Report

Nocardia can cause serious opportunistic infections in immunocompromised patients. Nocardial brain abscess in these patients has a high mortality. We describe a patient with Nocardia otitidiscaviarum brain abscess. After the abscess was evacuated at craniotomy, the patient was treated successfully with trimethoprim-sulfamethoxazole, meropenem, and amikacin.

The Role of Tigecycline in the Era with Multi-drug Resistant Organisms (MDROs) the Experience of a Medical Center in Taiwan

Background: With the rapid growing of multi-drug resistant organisms (MDROs) and a lack of newly developed antimicrobial agent, tigecycline has been given high hopes and expectations as a candidate to treat all these MDROs except Pseudomonas aeruginosa, Proteus mirabilis. Methods: All hospitalized adult subjects who received treatment with tigecycline were enrolled at a medical center in Northern Taiwan. Patients treated with tigecycline for 48 hours were excluded. Results: Almost half patients were shown to have successful clinical response to tigecycline (151/309; 49%), with high clinical success observed in complicated skin and skin structure infections (101/137; 74%). Treatment failure was mostly seen in hospital-acquired pneumonias with MDROs isolates (83/100; 83%). The mortality rate was 27% (84/309), which was mainly due to hospital acquired pneumonias (48/101; 48%). Conclusion: Our study show good efficacy of tigecycline in the treatment of complicated skin and skin structure infections. Regarding to the treatment of pneumonia, ineffective response was seen as most patients with HAP in our study. Its use in treating other infections not yet approved by the current guidelines requires further research to obtain enough evidence for future approval.