Yee Gyung Kwak

Risk factors for the acquisition of carbapenem-resistant Escherichia coli among hospitalized patients

Carbapenem resistance among Gram-negative bacilli has become an increasingly serious problem worldwide, and the emergence and spread of carbapenem-resistant Escherichia coli (CREC) is also becoming a serious problem. To date, however, risk factors for CREC acquisition have not been determined, so we decided to evaluate this in hospitalized patients through matched case-control study. Nosocomially acquired CREC was isolated from 46 patients between January 1997 and December 2007. For each patient, 3 matched-control subjects were selected. Previous use of carbapenem (adjusted odds ratio [AOR], 6.50) and metronidazole (AOR, 4.25), the presence of biliary drainage catheter (AOR, 4.59), and prior hospital stay (AOR 1.02) were found as independent risk factors for CREC. Our results suggest that the nosocomial acquisition of CREC may be favored by the selection pressure of carbapenems and metronidazole and also related to prior hospital stay and the presence of biliary drainage catheter.

Clinical Features and Outcomes of Bacteremia Caused by Enterococcus casseliflavus and Enterococcus gallinarum: Analysis of 56 Cases

The clinical significance and virulence potential of Enterococcus casseliflavus/flavescens and Enterococcus gallinarum are still uncertain. We retrospectively analyzed 56 cases of significant bacteremia caused by E. casseliflavus or E. gallinarum. Of these cases, 25 (44.6%) were associated with polymicrobial bacteremia, and 43 (76.8%) were associated with entry via the biliary tract. Resistance to vancomycin was observed in 17 (30.4%) of these 56 patients, and this resistance was significantly associated with E. gallinarum bacteremia (adjusted odds ratio [AOR], 10.56; 95% confidence interval [CI], 2.41-46.27) and bacteremia without biliary tract origin (AOR, 6.74; 95% CI, 1.44-31.67). The crude mortality rate was 13%, and the bacteremia-related mortality rate was 1.9%. In conclusion, bacteremia due to E. casseliflavus and E. gallinarum is commonly associated with biliary tract disease and may be associated with a low risk of mortality.

The impact of a ventilator bundle on preventing ventilator-associated pneumonia: A multicenter study

BACKGROUND For prevention of ventilator-associated pneumonia (VAP), a bundle approach was applied to patients receiving mechanical ventilation in intensive care units. The incidence of VAP and the preventive efficacy of the VAP bundle were investigated. METHODS A quasi-experimental study was conducted in adult intensive care units of 6 university hospitals with similar VAP rates. We implemented the VAP bundle between March 2011 and June 2011, then compared the rate of VAP after implementation of the VAP bundle with the rate in the previous 8 months. Our ventilator bundle included head of bed elevation, peptic ulcer disease prophylaxis, deep venous thrombosis prophylaxis, and oral decontamination with chlorhexidine 0.12%. Continuous aspiration of subglottic secretions was an option. RESULTS Implementation of the VAP bundle reduced the VAP rate from a mean of 4.08 cases per 1,000 ventilator-days to 1.16 cases per 1,000 ventilator-days. The incidence density ratio (rate) was 0.28 (95% confidence interval, 0.275-0.292). CONCLUSIONS Implementing the appropriate VAP bundle significantly decreased the incidence of VAP in patients with mechanical ventilation.

Clinical Significance of Spontaneous Aeromonas Bacterial Peritonitis in Cirrhotic Patients: A Matched Case-Control Study

BACKGROUND Although Aeromonas species are known to cause bacteremia in patients with cirrhosis, less is known about spontaneous bacterial peritonitis (SBP) caused by Aeromonas species in these patients. METHODS We performed a retrospective, matched case-control study (1:2 ratio) consisting of patients presenting with SBP due to Aeromonas species from January 1997 through December 2006. Control subjects were patients with SBP caused by other organisms and were matched to the patients by age (+/- 1 year) and sex. RESULTS We identified 43 patients with SBP due to Aeromonas species, 40 (93%) of whom had Aeromonas hydrophila infection and 3 (7%) of whom had Aeromonas sorbia infection. There were 81 control subjects, of whom 38 (47%) were infected with Escherichia coli, 25 (31%) were infected with Klebsiella species, 12 (15%) were infected with Streptococcus species, and 6 (7%) were infected with other bacteria. Baseline Child-Pugh class and model for end-stage liver disease score did not differ between groups. A significant increase in the incidence of infection during the warm season (July-September) was observed in the group with SBP due to Aeromonas species, compared with the group with SBP due to other bacteria (63% vs. 25%; P < .001). Diarrheal episodes were significantly more frequent in the group with SBP due to Aeromonas species (26% vs. 6%; P = .002). There were no statistically significant differences between groups with regard to appropriateness of initial antibiotic therapy,3-day mortality, and 30-day cumulative survival. In the group with Aeromonas infection, the in-hospital mortality rate was 23%; septic shock was the only independent prognostic factor of in-hospital mortality (odds ratio, 34.5;95% confidence interval, 1.9-640.6; P = .02). CONCLUSION Aeromonas species should be considered to be a causative organism of SBP in cirrhotic patients presenting with diarrheal episodes during the warm season. Compared with SBP caused by other organisms, SBP due to Aeromonas species was not associated with more-advanced cirrhosis.

Risk factors for device-associated infection related to organisational characteristics of intensive care units: findings from the Korean Nosocomial Infections Surveillance System.

Device-associated infections (DAIs) have been the major causes of morbidity and mortality of patients in intensive care units (ICUs). This study evaluated the risk factors for DAIs in ICUs. Ninety-six medical or surgical ICUs of 56 hospitals participated in the Korean Nosocomial Infections Surveillance System between July 2007 and June 2008. The occurrence of catheter-associated urinary tract infection (CAUTI), central line-associated bloodstream infection (CABSI), and ventilator-associated pneumonia (VAP) were monitored and DAI rates were calculated. Data associated with ICU characteristics were collected and Poisson regression was used for statistical analysis. Rates of CAUTI, CABSI, and VAP were 3.87 per 1000 urinary catheter days, 2.23 per 1000 central line days, and 1.89 per 1000 mechanical ventilator days, respectively. Rates of CAUTI were higher in ICUs in Seoul (P=0.032) and ICUs of major teaching hospitals (P=0.010). The ICUs of university-affiliated hospitals showed lower CAUTI rates (P=0.013). CABSI rates were higher in Seoul (P=0.001) and in medical ICUs (P=0.026). VAP rates were lower in ICUs of hospitals with more than 900 beds compared with hospitals with 400-699 beds (P=0.026). VAP rates were higher in surgical ICUs (P<0.0001) and increased 1.13-fold with each 100-unit increase in beds per infection control professional (P=0.003). The organisational and institutional characteristics of ICUs may influence DAI rates and there is a need for improvement in the incidence of VAP, CAUTI or CABSI.

Association of norB overexpression and fluoroquinolone resistance in clinical isolates of Staphylococcus aureus from Korea

OBJECTIVES Although the prevalence of fluoroquinolone resistance among methicillin-resistant Staphylococcus aureus (MRSA) is known to be higher than in methicillin-susceptible S. aureus (MSSA), the reasons have never been identified. METHODS We randomly selected 115 isolates of S. aureus collected from 10 different hospitals in Korea between June 2009 and May 2011. To investigate the difference in fluoroquinolone resistance mechanisms between MRSA and MSSA, we evaluated gyrA and parC mutations and the relative expression of the multidrug efflux pump genes norA, norB and norC. RESULTS All 62 ciprofloxacin-resistant S. aureus had either gyrA or parC mutations. The S84L mutation of gyrA (59/62, 95.2%) and the S80F mutation of parC (61/62, 98.4%) were the most common. Fifty-eight (93.6%) strains had both the S84L mutation of gyrA and the S80F mutation of parC. Among the 115 isolates, norB overexpression was the most common, occurring in 49 (42.6%) strains. There were only two (1.7%) strains with norA overexpression and none with norC overexpression. Strains overexpressing norB were more common among ciprofloxacin-resistant S. aureus (33/62, 53.2%) than ciprofloxacin-susceptible S. aureus (16/53, 30.2%) (P = 0.013). When we analysed 62 ciprofloxacin-resistant S. aureus strains, those overexpressing norB were more common in ciprofloxacin-resistant MRSA (28/46, 60.9%) than in ciprofloxacin-resistant MSSA (5/16, 31.3%) (P = 0.041). CONCLUSIONS Increased expression of norB can be a factor that contributes to ciprofloxacin resistance in MRSA strains.

Adverse events associated with the 2009 H1N1 influenza vaccination and the vaccination coverage rate in health care workers

We prospectively examined the 2009 H1N1 influenza vaccination coverage rate and the adverse events related to the monovalent vaccine in Korean health care workers. The H1N1 vaccination coverage rate was 91.7%. There were no significant adverse events discouraging the vaccination.

Trends in the incidence rate of device-associated infections in intensive care units after the establishment of the Korean Nosocomial Infections Surveillance System

BACKGROUND The effectiveness of continuous nationwide surveillance on healthcare-associated infections should be investigated in each country. AIM To assess the rate of device-associated infections (DAIs) in intensive care units (ICUs) since the establishment of the Korean Nosocomial Infections Surveillance System (KONIS). METHODS Nationwide data were obtained on the incidence rate of DAI in ICUs reported to KONIS by all participating hospitals. The three major DAIs were studied: ventilator-associated pneumonia (VAP), central line-associated bloodstream infection (CABSI), and catheter-associated urinary tract infection (CAUTI). The pooled and year-wise incidence rates (cases per 1000 device-days) of these DAIs were determined for the period 2006 and 2012. In addition, data from institutions that had participated in KONIS for at least three consecutive years were analysed separately. FINDINGS The number of ICUs participating in KONIS gradually increased from 76 in 2006 to 162 in 2012. Between 2006 and 2012, the incidence rate per 1000 device-days for VAP decreased significantly from 3.48 to 1.64 (F = 11, P < 0.01), for CAUTI the rate decreased non-significantly from 1.85 to 1.26 (F = 2.02, P = 0.07), and for CABSI the rate also decreased non-significantly from 3.4 to 2.57 (F = 1.73, P = 0.12). In the 132 ICUs that had participated in KONIS for at least three consecutive years, the VAP rate significantly decreased from the first year to third year (F = 20.57, P < 0.01), but the rates of CAUTI (F = 1.06, P = 0.35) and CABSI (F = 1.39, P = 0.25) did not change significantly. CONCLUSION The decreased incidence rate of VAP in ICUs in Korea might be associated with the continuous prospective surveillance provided by KONIS.

Impact of a national hospital evaluation program using clinical performance indicators on the use of surgical antibiotic prophylaxis in Korea

OBJECTIVES Clinical performance measurement in surgical antibiotic prophylaxis (SAP) was implemented as part of a national hospital evaluation program (NHEP) in Korea in 2007. This study investigated changes in SAP quality before and after the implementation of clinical performance measurement. METHODS The medical records of patients who underwent three types of surgery that were included for assessment in the NHEP (NHEP surgery) - arthroplasty, gastrectomy, and hysterectomy - and two other types of non-NHEP assessment surgery - craniotomy and spine surgery (non-NHEP surgery) - at six hospitals, from August to October in 2006-2008, were retrospectively reviewed. Three clinical indicators of SAP (antibiotic selection, timing of administration of the first dose, and duration) and the development of surgical site infections (SSIs) were compared before and after implementation. RESULTS A total of 1949 patients were enrolled: 356 arthroplasty, 273 gastrectomy, 615 hysterectomy, 168 craniotomy, and 537 spinal surgery. There were no significant changes in age, gender, wound class, or ASA score for each surgery during the study period. From 2007, SAP quality was significantly improved in NHEP surgery for the three clinical indicators. The timing of administration of the first dose was most markedly improved. SAP quality was also improved in non-NHEP surgery, but not as much as in NHEP surgery. Changes in the SSI rates for each surgery were not significant. CONCLUSIONS Hospital evaluation using clinical performance indicators can considerably improve the use of SAP. Further studies are warranted to investigate whether this hospital evaluation will decrease the development of SSIs.

Severity predictors in eschar-positive scrub typhus and role of serum osteopontin.

We prospectively evaluated severity predictors in terms of host, microorganism, and treatment factors in 153 eschar-positive scrub typhus patients. Severity was assessed with the Acute Physiology and Chronic Health Evaluation (APACHE) II score (< 10 versus ≥ 10) and predefined criteria of severe complications. Genotypes of Orientia tsutsugamushi were determined. Independent risk factors for severity (APACHE II score ≥ 10) were old age, diabetes mellitus, serum osteopontin > 100 ng/mL, and a group of underlying diseases (congestive heart failure, cerebrovascular disease, chronic liver disease, bronchial asthma, and chronic obstructive lung diseases). Anemia (≤ 10 g/dL) and C-reactive protein > 10 mg/dL were indicators of current severity. Neither the delay in antibiotics administration nor strain types (Boryong, Taguchi, or Kanda/Kawasaki) contributed to the severity. The risk factors for severe complications were similar. Serum osteopontin > 100 ng/mL had a negative predictive value of 96% for severe complications. This marker can be used to rule out severe disease status.