Primary Anti-retroviral Resistance in Treatment-naive HIV-infected Patients: A Korean HIV/AIDS Cohort Study

Primary anti-retroviral resistance is considered one of the major problems of HIV treatment. Contrary to reports from western countries, prior Korean studies have reported a relatively low primary resistance rate (less than 5%). Based on Korean HIV/AIDS cohort data, we estimated the primary resistance rate among treatment-naive HIV-infected patients. According to the results, the primary resistance rate was higher (8.8%) than reported previously in Korean studies. However, the major PI mutation was not found.

Primary Anti-retroviral Resistance in Treatment-naive HIV-infected Patients: A Korean HIV/AIDS Cohort Study

Primary anti-retroviral resistance is considered one of the major problems of HIV treatment. Contrary to reports from western countries, prior Korean studies have reported a relatively low primary resistance rate (less than 5%). Based on Korean HIV/AIDS cohort data, we estimated the primary resistance rate among treatment-naive HIV-infected patients. According to the results, the primary resistance rate was higher (8.8%) than reported previously in Korean studies. However, the major PI mutation was not found.

Clinical Characteristics and Risk Factors of Death among Patients with Vancomycin-Resistant Enterococci (VRE) during 8 Years (1994-2001) in a University Hospital

BACKGROUND: Vancomycin-resistant enterococci (VRE) infection is an emerging nosocomial problem. VRE usually multidrug-resistant, poses therapeutic dilemmas. The gene that encodes the resistance against vancomycin may spread the resistance to Staphylococcus aureus. However, there are no well-organized studies on the clinical manifestations and the factors that contribute to mortality in Korea. Herein, this study was focused on the clinical manifestations and mortality risks of patients with VRE infection during 8 years (1994-2001) in a university hospital. Understanding of the epidemiology and clinical manifestations of VRE would help develop control strategy of VRE outbreak in a hospital. METHOD: Sixty seven cases that had the VRE infection in Korea University Guro Hospital from January 1, 1994to December 12, 2001, were reviewed. We analyzed the risk factors of VRE infection and death by using univariable and multivariable statistic analyses. RESULTS: VRE infections have recently been increasing. Most of VRE infections were caused by Enterococcus faecium (85.1%) and Enterococcus faecalis (10.4%). Among 67 cases, 40 cases (59.7%) expressed VanA phenotype, 23 cases (34.3%) expressed VanB phenotype, and 3 cases expressed VanC phenotype (6%). The risk factors for death were renal dysfunction, central venous catheter insertion, and tracheostomy by using univariable analysis. The risk factor for death was renal dysfunction by using multivariable analysis. CONCLUSION: VRE has been increasing during the late 1990s in Korea. The VRE infection occurs especially in the patients who have renal dysfunction, long-term hospitalization, and ICU care. The implementation of careful isolation, infection control measures, prudent use of antibiotics, especially vancomycin, and periodic screening of patients populations are required to control VRE infection.

Clinical Characteristics and Risk Factors of Death among Patients with Vancomycin-Resistant Enterococci (VRE) during 8 Years (1994-2001) in a University Hospital

BACKGROUND: Vancomycin-resistant enterococci (VRE) infection is an emerging nosocomial problem. VRE usually multidrug-resistant, poses therapeutic dilemmas. The gene that encodes the resistance against vancomycin may spread the resistance to Staphylococcus aureus. However, there are no well-organized studies on the clinical manifestations and the factors that contribute to mortality in Korea. Herein, this study was focused on the clinical manifestations and mortality risks of patients with VRE infection during 8 years (1994-2001) in a university hospital. Understanding of the epidemiology and clinical manifestations of VRE would help develop control strategy of VRE outbreak in a hospital. METHOD: Sixty seven cases that had the VRE infection in Korea University Guro Hospital from January 1, 1994to December 12, 2001, were reviewed. We analyzed the risk factors of VRE infection and death by using univariable and multivariable statistic analyses. RESULTS: VRE infections have recently been increasing. Most of VRE infections were caused by Enterococcus faecium (85.1%) and Enterococcus faecalis (10.4%). Among 67 cases, 40 cases (59.7%) expressed VanA phenotype, 23 cases (34.3%) expressed VanB phenotype, and 3 cases expressed VanC phenotype (6%). The risk factors for death were renal dysfunction, central venous catheter insertion, and tracheostomy by using univariable analysis. The risk factor for death was renal dysfunction by using multivariable analysis. CONCLUSION: VRE has been increasing during the late 1990s in Korea. The VRE infection occurs especially in the patients who have renal dysfunction, long-term hospitalization, and ICU care. The implementation of careful isolation, infection control measures, prudent use of antibiotics, especially vancomycin, and periodic screening of patients populations are required to control VRE infection.

Clinical and Microbiological Feature of Quinolone-Resistant Klebsiella pneumoniae Pneumonia in a University Hospital / 감염

BACKGROUND: Klebsiella pneumoniae is an opportunistic pathogen which causes a spectrum of extra- intestinal infections. Since early 1980s, many outbreaks of extended-spectrum beta-lactamase (ESBL) producing K. pneumoniae have been reported. Using quinolone as an alternative therapeutic antibiotics also induced increased resistance to quinolones. Therefore, we evaluatedted the clinical and microbiological features of pneumonia caused by quinolone-resistant K. pneumoniae (QRKP). METHODS: From March of 1998 to April of 2000, 345 cases of K. pneumoniae pneumonia had been admitted to Korea University Guro Hospital. We retrospectively reviewed medical records of 75 cases. Thirty patients with pneumonia due to QRKP (case patients) were compared to 45 patients with pneumonia due to quinolone-susceptible K. pneumoniae (QSKP: control patients). We also performed antimicrobial susceptibility test (disc diffusion method and agar dilution method) and RAPD (random amplified polymorphic DNA) analysis to differentiate the isolates in resistant strains. RESULTS: Of 345 episodes of pneumonia, 30 (8.7 %) were caused by QRKP. Multivariate analysis re-vealed that prior antibiotics use was an independent risk factor for QRKP pneumonia. Among prior antibiotics, quinolone and the third generation cephalosporin were independently related to quinolone resistance. Although mortality rate was not high, QRKP pneumonia was associated with a significantly longer treatment duration and poor treatment response (P=0.009 and 0.007 respectively). According to the antimicrobial susceptibility test, quinolone resistance was significantly associated with the multi-drug resistance. RAPD analysis showed that 28 quinolone resistant strains belonged to only 4 genotypes, suggesting that patient- to-patient transmission of a few strains within the hospital occurred. CONCLUSION: QRKP pneumonia had a significant impact on clinical outcome and quinolone resistance was associated with multiple resistance to other antibiotics. It should be emphasized that judicious use of antibiotics as well as barrier precautions is required to reduce future outbreak and spread of QRKP.

Colonization Rate, Risk Factor for Acquisition and Genetic Diversity of Vancomycin-Resistant Enterococci (VRE) Isolated from Rectal Culture of Patients in Intensvie Care Units from Ten Large Hospitals in Korea / 감염

BACKGROUND: VRE have become an emerging nosocomial pathogen in Korea, but there has not been nationwide study on the colonization of VRE among high risk groups of hospitalized patients. The purpose of this study was to determine the prevalence of rectal colonization of VRE among patients hospitalized in the intensive care unit (ICU), to study the risk factors for nosocomial acquisition of VRE among those patients, to define the genetic diversity of VRE strains in major hospitals in Korea. METHODS: Between January the 20th and 30th of 2000, a point surveillance study was conducted in the ICU of the ten large hospitals, which were located nationwide. Surveillance rectal swab cultures for detecting VRE were obtained among 214 patients admitted to the ICU during the study period. To isolate VRE, rectal swab cultures were performed on Enterococcosel(R) agar that containing 6 microgram/mL of vancomycin. Minimal inhibitory concentrations (MICs) of vancomycin and teicoplanin were determined by agar dilution method. For the genotyping of VRE isolates, the detection of vanA, vanB, vanC1 and vanC2 gene by polymerase chain reaction was done. Pulsed-field gel electrophoreis (PFGE) was used for elucidating the genetic relatedness of VRE isolates. To identify the risk factors for rectal VRE colonization, patients harboring VRE were compared to patients who were not colonized with this organism. RESULTS: The rectal colonization rate of VRE was variable from 9.7% to 51.9% according to hospital. 64 VRE strains which were isolated from 63 patients included 37 E. feacium. 26 E. gallinarum and 1 E. casseliflavus isolates. Therefore the colonization rate of clinically significant vanA type VRE was 17.3% (37/ 214). 37 E. feacium. 26 E. gallinarum and 1 E. casseliflavus isolates were presented as vanA, vanC1 and vanC2 genotypes, respectively. Risk factors for rectal VRE colonization included the presence of chronic illness, previous use of broad spectrum antibioitcs es-pecillay vancomycin, and prolonged stay in ICU. Various PFGE patterns are noted among vanA type VRE isolates, so individual acquisition of VRE during stay in the majority of ICUs were suggested. But there is some evidence of focal VRE spread within the ICU and between hospitals. CONCLUSION: This study demonstrated the high rectal colonization rate (17.3%) of clinically significant vanA type VRE among patients admitted to the ICUs of ten large hospitals located nation-widely. This study suggested that practicing HICPAC guidelines, restricted vancomycin usage and periodic surveillance cultures in patients with high risk factors are important in preventing the emergence and spread of VRE infection among ICU patients.

Clinical Features of VRE Infection, Microbiologic Characteristics and Genetic Relatedness of VRE Isolates from Six University Hospitals / 감염

BACKGROUND: In recent years, vancomycin-resistant enterococci (VRE) have become one of major nosocomial pathogens in Korea. VRE infection presents as an increasingly difficult clinical problem in the treatment and management. The purpose of this study was to determine the clinical features, microbiologic characteristics, and genetic relatedenss of clinical VRE isolates which were collected from six university hospitals, distributed nationwide in Korea. In addition, we aimed to elucidate the possibility of VRE dissemination between hospitals. METHODS: During one year (January, 1999 to January, 2000), 107 clinically suspected VRE isolates were collected from six university hospitals and were subjected to vancomycin resistance genotyping by vanA, vanB, vanC1 and vanC2 PCR. Those 70 isolates with vanA genotype were examined antimicrobial susceptibility by agar dilution method. Pulsed-field gel electrophoreis (PFGE) were used for discriminating the genetic relatedness of VRE isolates. Clinical characteristics of the 61 patients with vanA VRE infection were analyzed for the identification of risk factors for VRE infection. RESULTS: Out of 107 clinical VRE isolates from six hospitals, 70 isolates (65.4%) were vanA genotype VRE (67 E. faecium, 3 E. faecalis). Their MIC90 of vancomycin, teicoplanin and ampicillin were >512 microgram mL, 512 microgrammL and >512 microgrammL respectively. The prevalance of high-level resistance to gentamicin and streptomycin were 96.9% and 78.1%, respectively. Prolonged hospital stay, cerebro-vascular disease, use of third generation cephalosporins, use of Foley catheter and levin tube were associated with VRE infection. 64 vanA VRE (61 E. faecium, 3 E. faecalis) had unique PFGE pattern within each hospital and showed no evidence of VRE transmission between hospitals. CONCLUSION: This study demonstrated the most common vancomycin resistance genotype among clini-cal VRE isolates in Korea were vanA type VRE. vanA genotype VRE had unique PFGE pattern within each hospital and showed no evidence of inter-hospital transmission. This study suggested that maintaining HICPAC guidelines, restricted vancomycin usage and periodic surveillance in patients with high risk factors are important in preventing the emergence and spread of VRE infection within hospitals.

Clinical Aspects and Prognostic Factors of Neutropenic Fever in Leukemic Patients: 1996~2001 / 감염

BACKGROUND: Cancer therapy-related infections due to neutropenia is a well known problem in cancer treatment. Leukemia increases the risk furthermore because of its nature of bone marrow involvement. Therefore knowledge of the aspects of infections in neutropenic leukemic patients are important in preventing morbidity and mortality. METHODS: This study was conducted by reviewing clinical records of 69 cases of 49 leukemic patients who had neutropenic fever during 1996~2001. Each case was reviewed and analyzed in terms of clinical status & treatment, laboratory results, origins of fever and pathogens (if origin was infectious), final outcome and prognostic factors. RESULTS: Of 69 cases of 49 leukemic patients with neutropenic fever, mortalilty was 29%. Microbiologically defined infection (MDI) was 45% and clinically defined infection (CDI) was 30.4%, which meant a increase in MDIs compared with the previous study. Major focuses of fever were lung, blood and catheter-related, which were similar to those of 1988~1995. The major pathogens were gram negative bacilli (43.2%), followed by gram positive cocci (29.7%), but the proportion of gram positive pathogens had increased. Age, usage of selective gut decontamination and colony-stimulating factors (CSFs), and the presence of bone marrow recovery were related to prognosis by univariate analysis. Multivariate logistic regression analysis revealed that the bone marrow recovery was the only significantly related to patient's outcome, which was the same as the previous study (P<0.001). CONCLUSION: Proportions of pathogens in febrile neutropenic patients were similar with the previous study, but gram positive infections are increasing recently. Bone marrow recovery was the only significant prognostic factor in these patients. And, the benefits of selective gut decontamination or CSF usage is still questionable.

Epidemiologic and Clinical Features of Adult Patients with Measles During 2000 Epidemic / 감염

BACKGROUND: Measles is an acute highly contagious infection caused by measles virus. Since the introduction of measles vaccines in 1963, measles has been dramatically decreased in Korea. However, measles outbreaks have occurred periodically every 4 to 6 years during the 1990s. During 2000, measles outbreak of large scale occurred throughout the country and the total of 32,088 cases were reported. The majority of affected population was infants and school-aged children, but measles was reported also among adolescent and adult population. There was no report about the epidemiology of adult measles cases during the last decade. In this study, we retrospectively analyzed the epidemiologic and clinical features of adult measles patients in Korea. METHODS: From July of 2000 to January of 2001, 50 adult cases of measles had been admitted to Korea University Hospital. Medical records of these 50 patients, who were clinically diagnosed as measles, were reviewed. Demographic data, clinical features, history of measles vaccination and laboratory findings were evaluated. RESULTS: The median age of patients was 23 years : 28 (56%) were male. Most cases (49/50, 98%) occurred between November of 2000 to January of 2001 and 8 (16%) patients were associated with outbreaks. The occupation of patients was diverse but, students (28%) and office workers (20%) were the most common. 44 (88%) of 50 patients had no underlying diseases. Adult measles patients demonstrated similar clinical symptoms, which were shown in children with measles. In laboratory findings, mean WBC count was 4,933/micro L and 18 (36%) patients had thrombocytopenia. 21 (42 %) patients had complication of measles, and hepatitis was the most common episodes among them. Measles vaccination history revealed that 5 (10%) had two-dose and 7 (14%) had one-dose measled vaccine. In 35 patients, measles IgM antibody test was done. It appears that IgM positive rate among one-dose measle vaccination group, two-dose measle vaccination group, and group with unknown vaccination history were 86% (6/ 7), 40% (2/5), and 78% (18/23), respectively. Most (94%) of patients were hospitalized and more than two-third of patients were isolated. All the patients were recovered without sequelae. CONCLUSION: In 2000 measles outbreak, adult measles had the typical clinical features similar to those in the children and the severe complication was rare. Adult measles patients demonstrated low measles vaccination rate and occurred mainly among the students and office workers.

Antibiotic Treatment of Methicillin-Resistant Staphylococcus epidermidis(MRSE) Infection

Staphylococcus epidermidis and other coagulase-negative staphylococci (CNS), often dismissed previously as culture contaminants, are assuming great clinical importance as true pathogens. CNS infections are associated with indwelling foreign bodies and increase along with increasing use of catheters and artificial devices inserted through the skin. CNS from nosocomial infections, particularly S. epidermidis, are usually resistant to multiple antibiotics, with more than 80% resistant to methicillin. Methicillin-resistant. epidermidis (MRSE) can become resistant to all β-lactams, cephalosporins, and carbapenems by the aquisition of a chromosomal mecA gene, which encodes penicillin-binding proteins 2a that has low affinity for β-lactams. S. epidermidis universally attaches to surface of indwelling artificial devices and catheters and produces extracellular polysaccharides, resulting in the formation of a biofilm. Biofilms increase resistance of S. epidermidis to antimicrobial agents and the potential to cause infections in patients with indwelling medical devices. The drug of choice for MRSE infection is glycopeptide antibiotics (e.g. vancomycin and teicoplanin) and cure rates have been improved by addition of gentamicin or rifampin. Recently developed noble antibiotics for Gram-positive bacteria, quinupristin/dalfopristin and linezolid, will play an important role in the treatment of serious MRSE infections. However, antibiotics alone often fail for cure and removal of indwelling medical devices may be crucial.