Prevalence and antimicrobial resistance of Klebsiella species isolated from clinically ill companion animals

Background@#Klebsiella spp. is an important conditional pathogen in humans and animals.However, due to the indiscriminate use of antibiotics, the incidence of antimicrobial resistance has increased. @*Objectives@#The purpose of this study was to investigate antimicrobial resistance in strains of Klebsiella strains and the phylogenetic relatedness of extended-spectrum cephalosporin (ESC)-resistance among Klebsiella strains isolated from clinically ill companion animals. @*Methods@#A total of 336 clinical specimens were collected from animal hospitals.Identification of Klebsiella species, determination of minimum inhibitory concentrations, detection of ESC resistance genes, polymerase chain reaction-based replicon typing of plasmids by conjugation, and multilocus sequence typing were performed. @*Results@#Forty-three Klebsiella strains were isolated and, subsequently, 28 were identified as K. pneumoniae, 11 as K. oxytoca, and 4 as K. aerogenes. Eleven strains were isolated from feces, followed by 10 from ear, 7 from the nasal cavity, 6 from urine, 5 from genitals, and 4 from skin. Klebsiella isolates showed more than 40% resistance to penicillin, cephalosporin, fluoroquinolone, and aminoglycoside. ESCresistance genes, CTX-M groups (CTX-M-3, CTX-M-15, and CTX-M-65), and AmpC (CMY-2 and DHA-1) were most common in the K.pneumoniae strains. Some K. pneumoniae carrying CTX-M or AmpC were transferred via IncFII plasmids. Two sequence types, ST709 and ST307, from K. pneumoniae were most common. @*Conclusions@#In conclusion, this is the first report on the prevalence, ESCresistance genotypes, and sequence types of Klebsiella strains isolated from clinically ill companion animals. The combination of infectious diseases and antimicrobial resistance by Klebsiella in companion animals suggest that, in clinical veterinary, antibiotic selection should be made carefully and in conjunction with the disease diagnosis.

Prevalence and antimicrobial resistance of Klebsiella species isolated from clinically ill companion animals

Background@#Klebsiella spp. is an important conditional pathogen in humans and animals.However, due to the indiscriminate use of antibiotics, the incidence of antimicrobial resistance has increased. @*Objectives@#The purpose of this study was to investigate antimicrobial resistance in strains of Klebsiella strains and the phylogenetic relatedness of extended-spectrum cephalosporin (ESC)-resistance among Klebsiella strains isolated from clinically ill companion animals. @*Methods@#A total of 336 clinical specimens were collected from animal hospitals.Identification of Klebsiella species, determination of minimum inhibitory concentrations, detection of ESC resistance genes, polymerase chain reaction-based replicon typing of plasmids by conjugation, and multilocus sequence typing were performed. @*Results@#Forty-three Klebsiella strains were isolated and, subsequently, 28 were identified as K. pneumoniae, 11 as K. oxytoca, and 4 as K. aerogenes. Eleven strains were isolated from feces, followed by 10 from ear, 7 from the nasal cavity, 6 from urine, 5 from genitals, and 4 from skin. Klebsiella isolates showed more than 40% resistance to penicillin, cephalosporin, fluoroquinolone, and aminoglycoside. ESCresistance genes, CTX-M groups (CTX-M-3, CTX-M-15, and CTX-M-65), and AmpC (CMY-2 and DHA-1) were most common in the K.pneumoniae strains. Some K. pneumoniae carrying CTX-M or AmpC were transferred via IncFII plasmids. Two sequence types, ST709 and ST307, from K. pneumoniae were most common. @*Conclusions@#In conclusion, this is the first report on the prevalence, ESCresistance genotypes, and sequence types of Klebsiella strains isolated from clinically ill companion animals. The combination of infectious diseases and antimicrobial resistance by Klebsiella in companion animals suggest that, in clinical veterinary, antibiotic selection should be made carefully and in conjunction with the disease diagnosis.

High-level mupirocin resistance in Gram-positive bacteria isolated from diseased companion animals

The purpose of this study was to investigate the high-level mupirocin resistance (HLMR) in Gram-positive bacteria isolated from companion animals. A total of 931 clinical specimens were collected from diseased pets. The detection of mupirocin-resistant bacteria and plasmid-mediated mupirocin resistance genes were evaluated by antimicrobial susceptibility tests, polymerase chain reactions, and sequencing analysis. Four-hundred and six (43.6%) bacteria were isolated and 17 (4.2%), including 14 staphylococci and 3 Corynebacterium were high-level mupirocin-resistant (MICs, ≥ 1,024 ug/mL) harboring mupA. Six staphylococci of HLMR strains had plasmid-mediated mupA-IS257 flanking regions. The results show that HLMR bacteria could spread in veterinary medicine in the near future.

Daclatasvir and asunaprevir combination therapy for patients with chronic hepatitis C virus genotype 1b infection in real world

BACKGROUND/AIMS@#Previous studies have reported a high rate of sustained virologic response (SVR) and a low rate of serious adverse events with the use of daclatasvir (DCV) and asunaprevir (ASV) combination therapy. We evaluated the efficacy and safety of DCV and ASV combination therapy for patients with chronic hepatitis C virus (HCV) genotype 1b infection in real world.@*METHODS@#We enrolled 278 patients (184 treatment-naïve patients) from five hospitals in Daegu and Gyeongsangbuk-do. We evaluated the rates of rapid virologic response (RVR), end-of-treatment response (ETR), and SVR at 12 weeks after completion of treatment (SVR12). Furthermore, we investigated the rate of adverse events and predictive factors of SVR12 failure.@*RESULTS@#The mean age of patients was 59.5 ± 10.6 years, and 140 patients (50.2%) were men. Seventy-seven patients had cirrhosis. Baseline information regarding nonstructural protein 5A (NS5A) sequences was available in 268 patients. Six patients presented with pretreatment NS5A resistance-associated variants. The RVR and the ETR rates were 96.6% (258/267) and 95.2% (223/232), respectively. The overall SVR12 rate was 91.6% (197/215). Adverse events occurred in 17 patients (7.9%). Six patients discontinued treatment because of liver enzyme elevation (n = 4) and severe nausea (n = 2). Among these, four achieved SVR12. Other adverse events observed were fatigue, headache, diarrhea, dizziness, loss of appetite, skin rash, and dyspnea. Univariate analysis did not show significant predictive factors of SVR12 failure.@*CONCLUSIONS@#DCV and ASV combination therapy showed high rates of RVR, ETR, and SVR12 in chronic HCV genotype 1b-infected patients in real world and was well tolerated without serious adverse events.

Lung Cancer Recurrence with Solitary Pancreatic Metastasis Mimicking Primary Pancreatic Cancer / 대한췌담도학회지

Pancreas metastasis of primary lung cancer is known to be very rare and if it occurs, most cases are disseminated malignant status and do not affect therapeutic plan. We experienced a case of lung cancer recurrence with solitary pancreas metastasis and mimicks primary pancreatic cancer. A 54-year old man was admitted to the hospital for further evaluation of pancreatic solitary mass. He underwent left pneumonectomy and adjuvant chemotherapy for treatment of lung adenocarcinoma 3 years ago. After surgical treatment, the lesion was confirmed metastatic adenocarcinoma of lung cancer origin. He was discharged and followed up for 24 months without recurrence.

Mycoplasma pneumoniae-associated Hepatitis without Lung Involvement / 대한소화기학회지

Mycoplasma pneumoniae (M. pneumoniae) is a major cause of community acquired respiratory infections. And it also causes a number of extrapulmonary manifestations including cardiovascular, dermatological, musculoskeletal, and hematological systems. But, acute hepatitis without lung involvement is rare in adults. Here, we report a case of 32-year-old man who presented with fever, chilling, myalgia, and headache. Biochemical analysis showed severely impaired liver function and leukopenia. Laboratory tests and liver biopsy demonstrated a hepatocellular pattern of M. pneumoniae-associated acute hepatitis. Clinical symptoms and laboratory parameters are improved rapidly under treatment with macrolide. Therefore, We recommend that phsycians should consider a possibility of M. pneumoniae infection in acute hepatitis without lung and extrapulmonary involvement, when other more frequent causes have been excluded.

Temporal Changes of Psychosocial Status in Neuroblastoma Survivors Over Time / 신경정신의학

OBJECTIVES: The survival rate of all childhood cancers has been increasing, and latent effects on childhood cancer survivors have been gaining researchers' attention. It has been shown that childhood cancer survivors experience social maladaptation and a decreased quality of life. Although neuroblastoma is one of the most common solid cancers in childhood, there are few reports on psychosocial status in neuroblastoma survivors. The purpose of this study was to investigate temporal changes in psychosocial status in neuroblastoma survivors. METHODS: This study was conducted by undertaking retrospective chart reviews of neuroblastoma survivors that were treated between January 1997 and February 2016 at Samsung Medical Center, Seoul, Korea. Among the 54 survivors identified, data for 28 patients who underwent psychological evaluation before and after treatment completion were selected for further analysis. We compared intelligence score, Korea-Child Behavior Checklist (K-CBCL), and Korean Personality Rating Scale for Children (K-PRC) scores before and after treatment completion. Time derivatives for each variable were calculated to identify temporal changes in scores. RESULTS: After treatment completion, K-CBCL scores for total competence (t=−2.34, p=0.044), somatic complaints (t=−2.43, p=0.022), and thought problems (t=−3.03, p=0.006) were higher than the scores prior to treatment. Familial relationship in K-PRC was significantly improved after treatment (t=2.11, p=0.045). Time derivatives of the significant K-CBCL subscales, except for the withdrawal and externalizing symptom scores, showed a tendency to increase with time. CONCLUSION: Although familial relationship and social competence improved after treatment, the levels of somatic complaints and thought problems increased following neuroblastoma treatment.

Antibacterial activities of bark extracts from Fraxinus rhynchophylla Hance and Geranium koreanum Kom. against clinical strains of Clostridium perfringens in chickens / 대한수의학회지

Necrotic enteritis (NE) caused by Clostridium (C.) perfringens commonly occurs in domestic broiler farms since antibiotic supplementation in poultry feed has been banned. We evaluated the antibacterial activities of medicinal plant extracts against C. perfringens isolates to select alternative compounds for preventing NE. We compared antibacterial activities using two methods and evaluated susceptibilities of the isolates based on minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC). Two (Fraxinus rhynchophylla Hance [FRH] and Geranium koreanum Kom. [GKK]) of the 30 plant extracts had potent antibacterial activities against C. perfringens ATCC 13124 in two assays. The MIC values for FRH and GKK against 20 C. perfringens isolates were 128~256 microg/mL and 32~128 microg/mL, respectively. The geometric MIC mean values for the two extracts were 147.2 microg/mL and 68.8 microg/mL, respectively. The MBCs for the two extracts against the same strains were 1,024~2,048 microg/mL and 256~1,024 microg/mL, respectively. The geometric mean MIC and MBC for GKK were about two-fold lower than those of FRH. The modified spot-on-lawn assay may be useful for measuring primary antibacterial potential. FRH and GKK are expected to be used as feed additives to prevent or treat NE in veterinary practice.

A Case of Mantle Cell Lymphoma Presenting as a Small Intestinal Stricture

Mantle cell lymphoma (MCL) is a subtype of B-cell non-Hodgkin's lymphoma (NHL), accounting for 3-10% of NHL. MCL involves the gastrointestinal (GI) tract in 10-30% of patients and common sites of MCL GI tract involvement are the colorectum and stomach, but any region of the GI tract may be involved. GI tract involvement by MCL usually presents in the form of multiple lymphomatous polyposis involving several segments of the GI tract. A few cases of MCL presenting with a GI tract stricture have been reported. Here, we present a rare case of a small intestinal stricture caused by MCL and review the literature of this disease.

A Case of Acute Lymphoblastic Leukemia Presenting with Protein-Losing Enteropathy / 대한소화기학회지

Protein-losing enteropathy (PLE) is a syndrome characterized by excessive gastrointestinal protein loss, resulting in hypoproteinemia and edema. A variety of benign and malignant conditions can be associated with PLE and acute leukemia is a very rare cause of PLE. We report a case of PLE associated with acute lymphoblastic leukemia. A 27-year-old man was admitted due to watery diarrhea, epigastric pain and bilateral leg edema. Laboratory findings showed hypoproteinemia and polycythemia. The diagnosis of PLE and acute lymphoblastic leukemia were confirmed on the measurement of fecal alpha1-antitrypsin clearance and bone marrow examination. After systemic chemotherapy and autologous stem cell transplantation, his clinical symptoms and abnormal laboratory findings were gradually improved.

A Case of Steroid-induced Hyperinfective Strongyloidiasis with Bacterial Meningitis / 대한소화기학회지

Strongyloides stercoralis is a soil transmitted intestinal nematode that is endemic in the tropical and subtropical regions. In most individuals who are infected, chronic, usually asymptomatic, gastrointestinal infection persists. But, in immunocompromized hosts or in patients receiving immunosuppressive therapy, autoinfection of S. stercoralis may result in the dissemination of larvae, leading to fatal hyperinfection and increased rate of complications. We report a case of hyperinfective strongyloidiasis with bacterial meningitis in a patient receiving steroid therapy. Strongyloidiasis was diagnosed by the presence of filariform larvae of S. stercoralis in the bronchoalveolar lavage cytology and upper gastrointestinal endoscopic biopsy specimen. Her clinical symptoms had progressively aggravated and developed bacterial meningitis during treatment. She died despite aggressive antibiotic and antihelminthic therapy.

A Case of Left Adrenal Gland Metastatic Cancer Diagnosed by Endoscopic Ultrasound-Guided Fine Needle Aspiration

With widespread use of imaging techniques, the discovery of adrenal incidentalomas is increasing recently. Benign tumors are more frequent than malignant tumors in adrenal incidentalomas. Among malignant adrenal incidentalomas, metastatic neoplasms are the most common etiology. Traditional techniques to obtain tissue of adrenal gland include percutaneous approach under computed tomography or abdominal ultrasound guidance as well as open or laparoscopic adrenalectomies. They are invasive and associated with considerable complications such as pneumothorax, pancreatitis, adrenal abscesses, bacteremia, needle-tract metastases, and hemorrhage. Currently, endo scopic ultrasound-guided fine needle aspiration (EUS-FNA) is increasingly used to obtain tissue for diagnosis if the lesion is located in close proximity to the gut lumen. Compared with the traditional percutaneous techniques of tissue acquisition, EUS-FNA has many advantages including less invasiveness and lower complication rate. Here, we report a case of metastatic non-small cell carcinoma of left adrenal gland diagnosed by EUS-FNA with a review of literature.

Distribution of Genomic Species and Antimicrobial Susceptibility in Acinetobacters Isolated from Gangjin Bay, Korea

A total of 90 Acinetobacter isolates from freshwater and seawater in Gangjin Bay of Korea was investigated for the distribution of genomic species, antimicrobial resistance patterns and clonal relatedness. By amplified ribosomal DNA restriction analysis, eighty-nine Acinetobacter isolates were classified into 11 Acinetobacter genomic species. A. johnsonii (n=23) was the most prevalent, followed by A. baumannii (n=13), A. calcoaceticus (n=13), Acinetobacter genomic species 11 (n=10), A. phenon 6/ct13TU (n=9), A. junii (n=5), A. venetianus (n=5), Acinetobacter genomic species 17 (n=4), 14BJ (n=3), A. phenon 10/1271 (n=2), Acinetobacter genomic species 3 (n=1), and ungrouped (n=1). The majority of Acinetobacter genomic species were isolated from the site A and B, and some known nosocomial pathogens in the clinical environment were observed among them. Of the 11 antimicrobial drugs tested, several A. johnsonii isolates exhibited high-frequency resistance to a wide variety of antimicrobial agents, including ampicillin-sulbactam, piperacillin, ceftazidime, cefotaxime, and sulfamethoxazole (p < 0.001). Some Acinetobacter genomic species were resistant to currently used antibiotics but all isolates were susceptible to imipenem, amikacin, and tetracycline. Based on the results of antimicrobial resistance pattern and phylogenetic analysis, 23 A. johnsonii isolates were classified into 19 pulsotypes. In conclusion, there was a significant difference in the distribution of Acinetobacter species between freshwater and seawater. Predominance of A. johnsonii strains was probably due to their ability to proliferate in the contaminated aquatic environment originated from local geographic features. Therefore, the waste effluent from animals and humans plays an important role in the distribution of Acinetobacter species in aquatic environment.

Genetic Identification and Phylogenetic Analysis of Anaplasma and Ehrlichia Species in Haemaphysalis longicornis Collected from Jeju Island, Korea

A total of 1,395 Haemaphysalis longicornis ticks collected from Jeju Island of Korea were examined by 16S rRNA gene-based nested PCR for the presence of infection with Anaplasma and Ehrlichia species. Template DNAs to detect the tick-borne pathogens were prepared from a total 506 tick pools. Eight genera of Anaplasma and six Ehrlichia by 16S rRNA gene PCR and sequencing analysis were identified. A. phagocytophilum was the most prevalent (27 [1.9%]) by nested PCR, followed by A. bovis (5 [0.4%]), E. chaffeensis (4 [0.2%]), and A. centrale (1 [0.1%]). In the phylogenetic analysis based on 16S rRNA sequences, eight genera of Anaplasma group (> 99.4% homology) and six Ehrlichia group (> 99.5% homology) were close to deposited A. marginale strains (AF309867, AF414874, and FJ226454) and Ehrlichia sp. (DQ324547), respectively. Three Anaplasma species groups A. phagocytophilum (group A), A. bovis (group B), and A. centrale (group C) and one Ehrlichia species E. chaffeensis (group D) were determined by comparing with Anaplasma and Ehrlichia related sequences. First, twenty-eight A. phagocytophilum clones belonging to group A were divided into 7 genotypes. The sequence similarity among genotypes A1 to A4 was very high (> 99.6%). Genotype B2 was close to A. bovis from Korea (99.7%). Genotype D1 was close to known E. chaffeensis strains (M73222, AF147752, and AY350424) and their similarity value was 99.7%. In conclusion, the genera of Anaplasma/Ehrlichia, A. phagocytophilum, and E. chaffeensis identified in predominant H. longicornis ticks were ubiquitous throughout the Jeju Island. The various native groups have been found through sequence identities and phylogenetic analysis.

Antimicrobial Resistance and Multilocus Sequence Typing of Vancomycin-Resistant Enterococcus faecium Isolated from Clinical Specimens

A total of 58 vancomycin-resistant E. faecium (VREF) was isolated from 3 hospitals located in Daegu, Korea. The VREF isolates were evaluated for the antimicrobial susceptibility pattern and resistance determinants against vancomcin, aminoglycosides, and macrolides. The multilocus sequence types (MLST) were determined to characterize the clonal diversity of the VREF isolates. The VREF isolates were highly resistance to teicoplanin, erythromycin, ciprofloxacin, gentamicin, and streptomycin, whereas quinupristin-dalfopristin and linezolid were the most susceptible drugs. All isolates carried the vanA gene. The aac6'-aph2" (n=53) and aadE (n=27) genes were detected in the high-level aminoglycoside resistant (HLAR) isolates. The aac6'-aph2" gene was located in the conjugally transferable plasmids. The ermB and ermA genes were detected in the 54 and 3 VREF isolates, respectively. The VREF isolates showed 11 different sequence types (ST). The VREF isolates belonging to ST192 was the most prevalent (n=19), but detected in one hospital, whereas the isolates belonging to ST203 (n=11) were detected in 3 hospitals. These results suggest that the VREF isolates resistant to aminoglycosides and erythromycin are originated from different clones and specific VREF clones are spread in the study hospitals.

Genetic Diversity of Stenotrophomonas maltophilia Isolated from Clinical Specimens

Stenotrophomonas maltophilia is a multi-drug resistant pathogen that has been isolated with increasing frequency from the hospitalized patients. A total of 202 S. maltophilia was isolated from three university hospitals and analysed by molecular typing for an epidemiologic investigation. All isolates were tested by antimicrobial susceptibility, random amplified polymorphic DNA (RAPD) analysis, and pulsed-field gel electrophoresis (PFGE). The RAPD and PFGE patterns were recorded and analysed by the unweighted-pair group method with arithmetic average method. Two or more isolates were considered to be clonally related if their PFGE pattern exhibited > or =80% similarity. Trimethoprim/ sulfamethoxazole and ciprofloxacin were the most active antimicrobial agents tested. The majority of the isolates found to be genetically unrelated by PFGE. The genetically related isolates were recovered from the same patient. The result demonstrates a high genetic diversity of S. maltophilia isolates from clinical specimens. The clonal diversity of S. maltophilia from the hospitalized patients is partly due to the strains originated from the hospital environments, but not horizontal transfer between the patients

Antimicrobial Resistance and Integrons Found in Commensal Escherichia coli Isolates from Healthy Humans

The emergence and spread of antimicrobial resistance among the pathogenic and commensal Enterobacteriaceae are of great concern worldwide. We characterized the antimicrobial resistance and integrons found in commensal Escherichia coli from healthy humans in the community. Class 1 integrase (intl1) and class 2 integrase (intl2) genes were identified in 22 (13.3%) and 2 (1.2%) of 165 E. coli isolates, respectively. dfrA17-aadA5 and dfrA1-aadA2 were the most common class 1 integrons. The prevalence of each type of class 1 integron among commensal E. coli isolates during 2001~2003 was similar to that of clinical E. coli isolates from hospital-acquired infections during 1994~1999. The resistant rates of commensal E. coli isolates carrying intl1 to ampicillin, streptomycin, gentamicin, sulfamethoxazole, trimethoprim, chloramphenicol, and tetracycline were significantly higher than those of intl1-negative E. coli isolates (p<0.05). Integrons were directly associated with multidrug resistance in commensal E. coli isolates. It is hypothesized that multidrug-resistant Enterobacteriaceae from hospital-acquired infections are a potential reservoir for integrons associated with resistance genes found in commensal E. coli isolates in the community

Epidemiology of Shigellosis in Korea

Shigellosis is an acute diarrheal disease caused by bacteria of the genus Shigella. Following the occurrence of a large outbreak of shigellosis as well as sporadic cases since 1998, shigellosis has been a major health problem in Korea. There have been major changes in epidemiology during the last five decades concerning shigellosis in terms of total incidence of shigellosis, prevalence of certain serogroups, selection of specific clones, and introduction of new Shigella clones. S. dysenteriae was the most prevalent species until the early twentieth century, S. flexneri was the most prevalent until the late 1980s, and S. sonnei has been the most prevalent since 1990. Diverse serotypes of S. dysenteriae (4 serotypes), S. flexneri (8 serotypes), and S. boydii (4 serotypes) were found during the Korean War and many of these Korean endemic Shigella strains circulated in the community until the late 1970s. However, the endemic strains of S. dysenteriae, S. boydii, and S. sonnei disappeared in the late 1980s. A new clone of S. sonnei that was introduced between the late 1980s and the early 1990s was responsible for a large proportion of shigellosis in recent years. S. flexneri serotype 4a was the most frequently found during the Korean War and then the incidence of S. flexneri 2a gradually increased with time. S. flexneri isolates detected from 1991 to 1997 were all serotype 2a. However, the diverse clones of S. flexneri reemerged in Korea since 1999. It has not been determined whether the S. flexneri strains from the 2000s were the descendants of the Korean endemic strains or imported new strains, but the PFGE patterns were different between S. flexneri strains from the 1980s and 2000s. The widespread of new S. sonnei strains and the persistence of S. flexneri strains are responsible for the endemicity of shigellosis in Korea.

Integron Carriage in Multiresistant Acinetobacter baumannii Strains

One hundred and eight Acinetobacter baumannii strains isolated from three university hospitals in Korea were investigated for the presence of integrons and its correlation with multiple antibiotic resistance. A. baumannii strains were classified into 23 different groups based on the biochemical tests, RAPD patterns, and antibiotic susceptibility. Many strains isolated from same hospital showed identical epidemiological markers: 75% of isolates from Gwangju, 53% from Seoul, and 39% from Cheonan appeared identical. Integrase genes were detected in 79 (73%) A. baumannii isolates. The intI1 and intI2 genes were detected in 73 (68%) and 10 (9%) isolates, respectively. Class 3 integrons were not detected. Integrase genes were detected in A. baumannii isolates from Gwangju and Seoul, but not in the strains from Cheonan. Based on the epidemiological grouping, most of A. baumannii strains affecting four or more patients carried integrons, while only one strain among the sporadic strains carried a class 2 integron. Integron-carrying A. baumannii strains were resistant to more antibiotics compared to the integron-negative strains. This result suggests that integron-carrying A. baumannii strains are more apt to spread nosocomially and to show multiple antibiotic resistances.

Molecular typing of Acinetobacter baumannii strains by randomly amplified polymorphic DNA (RAPD) analysis

Acinetobacter baumannii strains are emerging pathogens of the nosocomial infection with an increasing frequency in recent years. The therapeutic difficulty due to the wide spread of multiple resistant strains was major problem in A. baumannii infection. It seems likely that high frequency of A. baumannii infection will be increasing epidemiological importance in the future. However, the current limited understanding of the epidemiology of A. baumannii infections is caused by lack of a rapid and practical method for the molecular characterization of A. baumannii strains. This study was undertaken to determine molecular types and genetic similarity among A. baumannii strains isolated from four hospitals by RAPD analysis. Eighty-five strains, including 40 from Chunnam University Hospital, 27 from Dankook University Hospital, 15 from Yonsei University Hospital, and 3 from Seonam University Hospital, were classified into three molecular types. Molecular type II was the most common pattern and included 72 strains. All strains from Dankook University Hospital and 40 strains from Chunnam University Hospital belonged to molecular type I or II. A. baumannii strains form Yonsei University Hospital were very distant similarity values. The range of genetic similarity values among 85 strains of A. baumannii was 0.26 to 1.00. Although phenotypes including biotype and antimicrobial resistance pattern of A. baumannii strains were same or very similar to each other, their RAPD patterns were quite different. Typing with phenotypes was found to be less reliable than molecular typing by RAPD analysis. These results suggest that RAPD analysis provides rapid and simple typing method of A. baumannii strains for epidemiological studies. This work is the first epidemiological report of A. baumannii infections in Korea and it is hoped that results of this work may contribute to a better understanding of the clinical importance and epidemiology of A. baumannii strains.