Su-Pen Yang

Emergence of Carbapenem-Resistant Non-baumannii Species of Acinetobacter Harboring a blaOXA-51-Like Gene That Is Intrinsic to A. baumannii

ABSTRACT The blaOXA-51-like gene, originally intrinsic to Acinetobacter baumannii, had been detected in two clones of Acinetobacter nosocomialis and one clone of Acinetobacter genomic species “Close to 13TU.” These blaOXA-51-like genes, all preceded by ISAba1, were located on plasmids that might have originated with A. baumannii. The plasmid-borne ISAba1--blaOXA-51-like confers a high level of carbapenem resistance and affects the accuracy of using blaOXA-51-like detection as a tool for differentiating A. baumannii from other Acinetobacter species.

Eradication of multidrug-resistant Acinetobacter baumannii from the respiratory tract with inhaled colistin methanesulfonate: a matched case-control study

Repeated isolation of multidrug-resistant Acinetobacter baumannii (MDRAB) from respiratory secretions poses a great challenge for infection control. We conducted a retrospective case-control study to evaluate the efficacy and adverse effect of inhaled colistin methanesulfonate (CMS) in the eradication of MDRAB from the respiratory tract. Patients who were admitted to Taipei Veterans General Hospital between February 2009 and June 2010, had at least two sets of monomicrobial culture of MDRAB from respiratory secretions, and remained in hospital for at least 14 days after the first isolation of MDRAB (index day) were included. Patients who received intravenous CMS were excluded. Patients who received CMS inhalation for ≥ 3 days were selected as cases whereas the controls were matched for age and Acute Physiology and Chronic Health Evaluation II score. Thirty-nine cases and controls were identified. The duration of CMS inhalation was 10.9 ± 3.6 days. The use of inhaled CMS was the only independent factor associated with the eradication of MDRAB within 14 days after the index day (OR 266.33; 95% CI 11.26-6302.18, p <0.001), and shortened the duration of MDRAB recovery from the respiratory tract by 13.3 ± 1.45 days. The adverse effects were similar for both groups. The increase of colistin minimal inhibitory concentrations in the last isolate compared with the index isolate from the same patient did not differ between the two groups. In conclusion, our study demonstrated that inhaled CMS enhanced the eradication of MDRAB from the respiratory tract without significant clinical adverse effect or impact on colistin resistance.

A risk factor analysis of healthcare-associated fungal infections in an intensive care unit: a retrospective cohort study

BackgroundThe incidence of fungal healthcare-associated infection (HAI) has increased in a major teaching hospital in the northern part of Taiwan over the past decade, especially in the intensive care units (ICUs). The purpose of this study was to determine the factors that were responsible for the outbreak and trend in the ICU.MethodsSurveillance fungal cultures were obtained from “sterile” objects, antiseptic solutions, environment of infected patients and hands of medical personnel. Risk factors for comparison included age, gender, admission service, and total length of stay in the ICU, Acute Physiology and Chronic Health Evaluation (APACHE) II scores at admission to the ICU, main diagnosis on ICU admission, use of invasive devices, receipt of hemodialysis, total parenteral nutrition (TPN) use, history of antibiotic therapy before HAI or during ICU stay in no HAI group, and ICU discharge status (ie, dead or alive). Univariable analysis followed by multiple logistic regression analysis was performed to identify the independent risk factors for ICU fungal HAIs and ICU mortality.ResultsThere was a significant trend in ICU fungal HAIs from 1998 to 2009 (P < 0.001). A total of 516 episodes of ICU fungal HAIs were identified; the rates of various infections were urinary tract infection (UTI) (54.8%), blood stream infection (BSI) (30.6%), surgical site infection (SSI) (6.6%), pneumonia (4.5%), other sites (3.5%). The fungi identified were: yeasts (54.8%), Candida albicans (27.3%), Candida tropicalis (6.6%), Candida glabrata (6.6%), Candida parapsilosis (1.9%), Candida species (0.8%), and other fungi (1.9%). Candida albicans accounted for 63% of all Candida species. Yeasts were found in the environment of more heavily infected patients. The independent risk factors (P < 0.05) of developing ICU fungal HAIs from all sites were TPN use, sepsis, surgical patients, mechanical ventilation and an indwelling urinary catheter. The independent risk factors for ICU fungal UTI included TPN use, mechanical ventilation and an indwelling urinary catheter. The independent risk factors for ICU fungal BSI included TPN use, sepsis, and higher APACHE II score. The independent risk factors for ICU fungal pneumonia included TPN use, surgical patients. The independent risk factors for ICU fungal SSI included surgical patients, and TPN use. The odds ratios of TPN use in various infection types ranged from 3.51 to 8.82. The risk of mortality in patients with ICU fungal HAIs was over 2 times that of patients without ICU HAIs in the multiple logistic regression analysis (P < 0.001).ConclusionsThere was a secular trend of an increasing number of fungal HAIs in our ICU over the past decade. Patients with ICU fungal HAIs had a significantly higher mortality rate than did patients without ICU HAIs. Total parenteral nutrition was a significant risk factor for all types of ICU fungal HAIs, and its use should be monitored closely.

Changes in the incidence of candidaemia during 2000–2008 in a tertiary medical centre in northern Taiwan

Candidaemia is associated with high mortality and high healthcare costs. The incidence of candidaemia in Taiwan rose markedly during the period 1980-2000. We conducted this hospital-based surveillance study in order to explore the secular trend in incidence of candidaemia during the period 2000 to 2008. In our study, Candida spp. were the fourth most common cause of bloodstream infections, with a 30-day crude mortality rate of 36.7%. Candida albicans was the most common species identified, although mortality rate did not differ significantly among species. The incidence of candidaemia began to decrease in 2004. Risk factors related to higher mortality included longer hospital stay before onset of candidaemia, liver cirrhosis, malignancy, end-stage renal disease requiring renal dialysis, dependence on mechanical ventilation and urinary catheterisation.

Associated clinical characteristics of patients with candidemia among different Candida species

BACKGROUND The rising incidence of non-albicans Candida (NAC) infection has been associated with a potentially adverse outcome for patients with candidemia. However, categorizing various species causing candidemia into a single NAC group might lead to inappropriate conclusions due to heterogeneity in species. Thus we examined the associated factors among patients with candidemia caused by different species. METHODS This retrospective study was conducted at a tertiary medical center in Taiwan from 2006 to 2009. Mortality rate, demographic and clinical characteristics, albumin levels, and severity scores of acute illness of patients at the onset of candidemia were analyzed. RESULTS A total of 447 episodes among 418 patients were included for analysis. The overall 30-day crude mortality was 48.2%, with no significant difference between C. albicans and NAC candidemia, but apparently C. parapsilosis candidemia was associated with a lower mortality rate. Time to positivity for yeast was significantly different between species. Compared with infection involving C. albicans, more frequent use of total parenteral nutrition, lower Sequential Organ Failure Assessment score and higher albumin levels were observed for C. parapsilosis candidemia. CONCLUSION Identifying associated factors for each species may be a more effective approach than single NAC grouping. Time to positivity may be a hint for treatment guidance in candidemia. More frequent use of total parenteral nutrition and less virulent nature were noted for C. parapsilosis candidemia.

Amino acid substitutions of quinolone resistance determining regions in GyrA and ParC associated with quinolone resistance in Acinetobacter baumannii and Acinetobacter genomic species 13TU

BACKGROUND AND PURPOSE Amino acid substitutions in GyrA and ParC are associated with resistance to quinolones in Acinetobacter baumannii (A baumannii), but this association is rarely elucidated in Acinetobacter genomic species (AGS) 13TU. This study aims to compare the association of amino acid substitutions in GyrA and ParC with quinolone resistance in A baumannii and AGS 13TU in Taiwan. METHODS Eleven representative strains of A baumannii and 13 strains of AGS 13TU were selected from 402 bacteremic isolates. The sequences of quinolone resistance determining regions of gyrA and parC were determined. Minimal inhibitory concentrations (MICs) of nalidixic acid, ciprofloxacin, levofloxacin and moxifloxacin were determined by agar dilution method. RESULTS Ser83Leu substitution in GyrA in A baumannii (one strain) was associated with resistance to all tested quinolones. This substitution plus a Ser80Leu or Ser80Tyr in ParC in A baumannii (four strains) and AGS 13TU (two strains) were associated with higher MICs of all quinolones. All but one quinolone MICs of A baumannii (one strain) and AGS 13TU (two strains) carrying a single substitution Ser56Asn in ParC remained in the susceptibility breakpoint. The Ser83Leu substitution in GyrA, even with additional Ser56Asn substitution in ParC, was associated with resistance to only nalidixic acid, but not other newer quinolones in AGS 13TU (two strains). CONCLUSION A baumannii and AGS 13TU possessed similar quinolone resistance associated with amino acid substitutions in GyrA and ParC. Further study with more strains is needed to determine whether a single Ser83Leu substitution in GyrA was associated with a high level of quinolone MIC only in A baumannii, but not in AGS 13TU.

Prognostic factors of candidemia among nonneutropenic adults with total parenteral nutrition

BACKGROUND Immediate removal of central venous catheters (CVCs) is not possible in patients with candidemia requiring total parenteral nutrition (TPN). This study analyzed the possible prognostic factors for survival time after onset of candidemia among nonneutropenic adults requiring TPN. METHODS We conducted a retrospective analysis from September 2003 to August 2005. RESULTS A total of 59 nonneutropenic adults with candidemia and requiring TPN were identified retrospectively. All Candida isolates were susceptible to flucytosine and amphotericin B. With the exception of one C glabrata isolate, all other isolates were susceptible to fluconazole and itraconazole. The only predictor of 30-day survival rate after onset of candidemia identified in our analysis was an Acute Physiology and Chronic Health Evaluation II (APACHE II) score of 23 points or less. Adults with higher APACHE II scores, who did not have their CVCs changed, did not receive antifungal treatment, or who had thrombocytopenia had shorter survival times after the onset of candidemia. CONCLUSIONS APACHE II scores, thrombocytopenia, antifungal agents, and CVCs changes are associated with survival time in nonneutropenic adults requiring TPN after the onset of candidemia.

Clinical significance of time to positivity for yeast in candidemia

PURPOSE Candidemia is an important issue of nosocomial bloodstream infections, and is associated with a high mortality rate. However, little information is available before final species identification, which takes days after the episode of candidemia. This study tried to determine whether time to positivity (TTP) for yeast helps in predicting the species of candidemia. METHODS A retrospective cohort study was conducted in Taiwan, which included 434 episodes of nonduplicated candidemia during the period between 2006 and 2009. The demographic features, clinical characteristics, TTP for yeast, and acute illness scores were included for analysis. RESULTS The mean age of patients with candidemia was 70.4 ± 15.2 years, and the 30-day crude mortality rate was 48.2%. Forty-five percent of patients suffered from shock status with a mean Acute Physiological and Chronic Health Evaluation II score of 27.0 ± 8.7 and a mean Sequential Organ Failure Assessment score of 9.7 ± 4.5, whereas 50% were admitted to the intensive care units. Candida albicans was still the most commonly identified pathogen (58.1%), followed by C. tropicalis (14.7%), C. parapsilosis (13.1%), and C. glabrata (8.3%). Results of multivariate logistic regression showed that TTP for yeast within 48 hours would more favor C. tropicalis (p = 0.044), and less favor C. glabrata (p = 0.025) and C. parapsilosis (p < 0.001). Patients with parenteral nutrition usage were more frequently associated with a TTP for yeast within 48 hours, whereas those with previous exposure to an antifungal agent had a longer TTP for yeast. CONCLUSION The TTP for yeast might provide a hint of the responsible Candida species before final identification among critical patients with candidemia. The association between antifungal agents and TTP would need more evidence for elucidation.