Genetic populations of Bacillus anthracis isolates from Korea

Bacillus (B.) anthracis is the pathogen that causes fatal anthrax. Strain-specific detection of this bacterium using molecular approaches has enhanced our knowledge of microbial population genetics. In the present study, we employed molecular approaches including multiple-locus variable-number tandem repeat analysis (MLVA) and canonical single-nucleotide polymorphism (canSNP) analysis to perform molecular typing of B. anthracis strains isolated in Korea. According to the MLVA, 17 B. anthracis isolates were classified into A3a, A3b, and B1 clusters. The canSNP analyses subdivided the B. anthracis isolates into two of the three previously recognized major lineages (A and B). B. anthracis isolates from Korea were found to belong to four canSNP sub-groups (B.Br.001/2, A.Br.005/006, A.Br.001/002, and A.Br.Ames). The A.Br.001/002 and A.Br.Ames sub-lineages are closely related genotypes frequently found in central Asia and most isolates were. On the other hand, B. anthracis CH isolates were analyzed that belonged to the B.Br.001/002 sub-group which found in southern Africa, Europe and California (USA). B.Br.001/002 genotype is new lineage of B. anthracis in Korea that was not found before. This discovery will be helpful for the creation of marker systems and might be the result of human activity through the development of agriculture and increased international trade in Korea.

Epidemic by Salmonella I 4,5,12:i:- and Characteristics of Isolates in Korea / 감염과화학요법

BACKGROUND: Salmonella I 4,[5],12:i:- was first reported as a new serovar by the Spanish National Reference Laboratory in 1997. Thereafter, several outbreaks caused by this serovar have been reported, indicating worldwide transmission. MATERIALS AND METHODS: Stool samples and patient data were collected from diarrhea cases in an outbreak at Daegu city in 2008. Salmonella isolates were characterized by phage typing, antibiotic resistance profile and flagella gene deletion. Deposited isolates in the EnterNet-Korea, acute diarrheal surveillance system, were also screened for this serovar. RESULTS: Isolates from diarrhea patients in the Daegu outbreak (2008) were identified as Salmonella I 4,[5],12:i:-. Screening the deposited isolates in the EnteroNet-Korea revealed that an unidentifed isolate in 2001 was the Salmonella I 4,[5], 12:i:-. CONCLUSIONS: Salmonella I 4,[5],12:i:-. was the causative pathogen of the 2008 foodborne outbreak of salmonellosis in Daegu City. Retrospective screening revealed that Salmonella I 4,[5],12:i:- was present in Korea as early as 2001.

The Laboratory Diagnosis of Melioidosis in a Korean Patient

Burkholderia pseudomallei is a gram-negative opportunistic intracellular pathogen that causes an acute and fatal septicemic melioidosis in humans. The organism is mainly found in Southeastern Asia and Northern Australia. Recently, we encountered a case of melioidosis in a Korean patient and performed the laboratory diagnosis of melioidosis. As a result, a gram negative bacterium was isolated from a melioidosis patient, and it was identified as B. pseudomallei on DNA sequencing of 16S ribosomal RNA with 99.9% homology and biochemical examination of VITEK gram-negative identification card. Also, DNA from cultured bacteria was tested in multiplex PCR, a 245 bp fragment amplified from the metalloprotease gene and a fragment of variable size ranging from 400~700 bp resulting from amplification of the 10 bp repetitive element for B. pseudomallei were confirmed after electrophoresis. The bacterium was sensitive to ceftazidime, imipenem and meropenem but resistant to ticarcillin. So far, there are no domestic cases of melioidosis in Korea, however, due to the increase in international travelers, the incidence of melioidosis is likely to increase. We report a recent case of melioidosis in a Korean patient.

Korean Nosocomial Infections Surveillance System, Intensive Care Unit Module Report: Data Summary from July 2009 through June 2010 / 병원감염관리

BACKGROUND: In this report, we present the annual data of the intensive care unit (ICU) module of the Korean Nosocomial Infections Surveillance System (KONIS) from July 2009 through June 2010. METHODS: We performed a prospective surveillance of nosocomial urinary tract infections (UTIs), bloodstream infections (BSIs), and pneumonia (PNEU) at 116 ICUs in 63 hospitals by using KONIS. Nosocomial infection (NI) rates were calculated as the number of infections per 1,000 patient-days or device-days. RESULTS: We identified 3,965 NIs during the study period: 2,156 cases of UTIs (2,119 were urinary catheter-associated), 1,110 cases of BSIs (948 were central line-associated), and 699 cases of PNEU (410 were ventilator-associated). The rate of urinary catheter-associated UTIs (CAUTIs) was 4.75 cases per 1,000 device-days (95% confidence interval, 4.55-4.95), and urinary catheter utilization ratio was 0.86 (range, 0.859-0.861). The rate of central line-associated BSIs was 3.28 (range, 3.07-3.49), and the utilization ratio was 0.56 (range, 0.559-0.561). The rate of ventilator-associated PNEUs (VAPs) was 1.95 (range, 1.77-2.15), and the utilization ratio was 0.41 (range, 0.409-0.411). Although ventilator utilization ratio was lower in the hospitals with 400-699 beds than in the hospitals with 700-899 beds and more than 900 beds, the rate of VAPs were higher in the hospitals with 400-699 beds than in hospitals with 700-899 beds and more than 900 beds. The incidence of infections due to imipenem-resistant Acinetobacter baumannii increased from 43.6% to 82.5% since July 2006. CONCLUSION: The risk of acquiring VAP and CAUTI is highest in the ICUs of hospitals with 400-699 beds than that in hospitals with more beds. Imipenem-resistant A. baumannii was identified as an emerging gram-negative pathogen of nosocomial infections.

Bloodstream Infections and Clinical Significance of Healthcare-associated Bacteremia: A Multicenter Surveillance Study in Korean Hospitals

Recent changes in healthcare systems have changed the epidemiologic paradigms in many infectious fields including bloodstream infection (BSI). We compared clinical characteristics of community-acquired (CA), hospital-acquired (HA), and healthcare-associated (HCA) BSI. We performed a prospective nationwide multicenter surveillance study from 9 university hospitals in Korea. Total 1,605 blood isolates were collected from 2006 to 2007, and 1,144 isolates were considered true pathogens. HA-BSI accounted for 48.8%, CA-BSI for 33.2%, and HCA-BSI for 18.0%. HA-BSI and HCA-BSI were more likely to have severe comorbidities. Escherichia coli was the most common isolate in CA-BSI (47.1%) and HCA-BSI (27.2%). In contrast, Staphylococcus aureus (15.2%), coagulase-negative Staphylococcus (15.1%) were the common isolates in HA-BSI. The rate of appropriate empiric antimicrobial therapy was the highest in CA-BSI (89.0%) followed by HCA-BSI (76.4%), and HA-BSI (75.0%). The 30-day mortality rate was the highest in HA-BSI (23.0%) followed by HCA-BSI (18.4%), and CA-BSI (10.2%). High Pitt score and inappropriate empirical antibiotic therapy were the independent risk factors for mortality by multivariate analysis. In conclusion, the present data suggest that clinical features, outcome, and microbiologic features of causative pathogens vary by origin of BSI. Especially, HCA-BSI shows unique clinical characteristics, which should be considered a distinct category for more appropriate antibiotic treatment.

Further Evaluation of Multiplex PCR for Rapid Detection of Salmonella Typhi / 감염과화학요법

Typhoid fever is a class I legally designated communicable disease in Korea; and if remains as an important public health problem in many developing countries. It takes at least 3-5 days to detect and identify Salmonella Typhi (S. Typhi) by classical diagnostic method. For this reason, multiplex PCR (mPCR) was evaluated in detecting and identifying S. Typhi. In this study, forty-three bacterial strains, which consisted of 42 Salmonella enterica serovars and one Citrobacter freundii. were used to evaluate the promptness of mPCR in detecting and identifying S. Typhi. mPCR was performed with four genes which were known for representing Salmonella spp and/or S. Typhi: invA, fliC-d, viaB and prt. invA and prt gene was amplified in all strains and viaB gene was in only S. Typhi. fliC-d gene was amplified in three serovars: S. Typhi, S. Schwarzengrund and S. Livingstone. After specificity test, mPCR was modified as triplex PCR with three genes (invA, fliC-d, and viaB) and the sensitivity test was performed against S. Typhi-inoculated stool samples. mPCR was able to detect S. Typhi cell suspension of 1x105 cfu/mL. We found that modified multiplex PCR was useful to detect S. Typhi from stool samples within 24h whereas it takes 3-5days to detect by classic diagnosis method.

Korean Nosocomial Infections Surveillance System, Intensive Care Unit Module Report: Data Summary from July 2008 through June 2009 and Analysis of 3-Year Results / 병원감염관리

BACKGROUND: In this report, we present the annual data of the intensive care unit (ICU) module of the Korean Nosocomial Infections Surveillance System (KONIS) from July 2008 through June 2009. METHODS: We performed a prospective surveillance of nosocomial urinary tract infections (UTI), bloodstream infections (BSI), and pneumonia (PNEU) at 101 ICUs in 57 hospitals using KONIS. Nosocomial infection (NI) rates were calculated as the numbers of infections per 1,000 patient-days or device-days. RESULTS: We identified 3,287 NIs during the study period: 1,787 UTIs (1,772 cases were urinary catheter-associated), 917 BSIs (797 were central line-associated), and 583 PNEUs (335 were ventilator-associated). The rate of urinary catheter-associated UTIs was 4.80 cases per 1,000 device-days (95% confidence interval, 4.58-5.03) and urinary catheter utilization ratio was 0.85 (0.849-0.851). Although the urinary catheter utilization ratios were lower in the hospitals with 400-699 beds than in the hospitals with 700-899 beds and more than 900 beds, the rates of urinary catheter-associated UTIs were higher in hospitals with 400-699 beds than in the larger ones. The rate of central line-associated BSIs was 3.27 (3.05-3.51) and the utilization ratio was 0.56 (0.559-0.561). The rate of ventilator-associated PNEUs was 1.86 (1.67-2.07) and the utilization ratio was 0.41 (0.409-0.411). The rate of ventilator-associated PNEUs was lower in July 2008-June 2009 than in July 2007-June 2008 and July 2006-December 2006. CONCLUSION: It appears that the KONIS influences the reduction in the rate of device-associated infections, especially ventilator-associated PNEU; therefore, ongoing targeted surveillance and infection control strategies are needed to control device-associated infections.

The Korean Surgical Site Infection Surveillance System Report, 2009 / 병원감염관리

BACKGROUND: A nationwide prospective multicenter study was performed in Korea to determine the incidence and risk factors for surgical site infections (SSI) after craniotomies (CRAN), ventricular shunt operations (VS), gastric operations (GAST), colon operations (COLO), rectal operations (RECT), hip joint replacements (HJR), and knee joint replacements (KJR). METHODS: We collected data regarding demographics, clinical and operative risk factors for SSI, and antibiotics administered to the patients who underwent CRAN in 18 hospitals, VS in 19 hospitals, GAST in 19 hospitals, COLO in 19 hospitals, RECT in 19 hospitals, HJR in 24 hospitals, and KJR in 23 hospitals between January and December 2009. All the data were collected using a real-time web-based reporting system. RESULTS: The SSI rate of CRAN, VS, GAST, COLO, RECT, HJR, and KJR was 3.68 (22/1,169), 5.96 (14/235), 4.25 (75/1,763), 3.37 (22/653), 5.83 (27/463), 1.93 (23/1,190), and 2.63 (30/1,139), respectively, per 100 operations. The only significant risk factor for SSI after CRAN was postoperative cerebrospinal fluid leakage. The independent risk factors for SSI after GAST were multiple procedure, reoperation, infection of other sites, and transfusion. In HJR, the duration of preoperative hospital stay and operation time were longer, and the need for general anesthesia, transfusion, and steroid use and the incidence of contaminated/dirty wound, obesity, and infection of other sites were significantly increased in the infected group. In KJR, the duration of preoperative hospital stay was longer and the need for reoperation was significantly higher in the infected group, and in addition, the incidence of SSI was higher among males. CONCLUSION: The maintenance of surveillance on SSI is very important because surveillance provides valuable information to the surgeon and infection control personnel, which in turn helps decrease the incidence of SSI.

Korean Nosocomial Infections Surveillance System, Intensive Care Unit Module Report: Data Summary from July 2007 through June 2008 / 병원감염관리

BACKGROUND: This is the first annual data on the surveillance of intensive care unit (ICU) module by the Korean Nosocomial Infections Surveillance System (KONIS) from July 2007 through June 2008. METHODS: The KONIS performed a prospective surveillance for nosocomial urinary tract infections (UTI), bloodstream infections (BSI), and pneumonia (PNEU) at 96 ICUs in 56 hospitals. Nosocomial infection (NI) rates were calculated as the numbers of infections per 1,000 patient-days or device-days. RESULTS: A total of 2,637 NIs were found during the study period; 1,391 UTIs (1,365 cases were urinary catheter-associated), 667 BSIs (563 were central line-associated), and 579 PNEUs (357 were ventilator-associated). The rate of urinary catheter-associated UTIs was 4.43 cases per 1,000 device-days (95% confidence interval, 4.20-4.67) and urinary catheter utilization ratio was 0.84 (0.839-0.841). The rate of central line-associated BSIs was 2.83 (2.61-3.07) and the utilization ratio was 0.54 (0.538-0.542). The rate of ventilator-associated PNEUs was 2.49 (2.25-2.76) and the utilization ratio was 0.39 (0.388-0.392). Although the ventilator utilization ratios were lower in the hospitals with less than 900 beds than in the hospitals with more than 900 beds, the rates of ventilator-associated PNEUs were higher in the smaller hospitals than in the larger ones. CONCLUSION: This result suggests that ongoing targeted surveillance and implementation of proven infection control strategies are needed.

Development of Capture ELISA Using a Biotinylated Monoclonal Antibody for Detection of Botulinum Neurotoxin Type A

A capture enzyme-linked immunosorbent assay (capture ELISA) was developed to detect Clostridium botulinum neurotoxin type A (BoNT/A) in assay buffer and human serum. The assay is based upon affinity-purified rabbit polyclonal and biotinylated monoclonal antibodies directed against the BoNT/A complex purified from C. botulinum ATCC19397. For the capture ELISA, the optimized amount (2 microgram/ml) of rabbit polyclonal antibody was immobilized on ELISA plates to detect BoNT/A (ranging from 0 to 500 ng/ml), which was recognized by 2 microgram/ml of the monoclonal antibody. From three independent repeated experiments, standard curves were linear over the range of 0~31.25 ng/ml BoNT/A and the coefficients (r(2)) ranged from 0.9951~0.9999 for all assays. The inter-variations were typically 0.50~6.93% and the specificity was confirmed by showing no cross-reactivity against BoNT/B and /E. The detection limit of capture ELISA was 0.488 ng/ml, which was close to mouse LD(50). In addition, application with BoNT/A-spiking human sera showed a possibility to detect BoNT/A with capture ELISA from the contaminated human sera. Taken together, the newly developed capture ELISA could serve as a rapid and sensitive screening tool for detecting BoNT/A simultaneously from massive specimens.

Korean Nosocomial Infections Surveillance System (KONIS) Report: Data Summary from July through September 2006 / 병원감염관리

BACKGROUND: THe Korean Society for Nosocomial Infection Control (KOSNIC) orfanized the Korean Nosocomial Infections Surveillance System (KONIS) to establish a nationwide database of Nosocomial infection (NI) rate in the intensive care units (ICUs) of Korean hospitals. This report is a summary of the data from July through September 2006. METHODS: The KONIS performed a prospective sruveillance for nosocomial urinary tract infections (UTI), bloodstream infections (BSI), and pneumonia (PNEU) at 76 ICUs in 44 hospitals. NI rates were calculated as the numbers of infections per 1,000 patient-days or device-days. RESULTS: A total of 846 nosocomial infections were fOlllld during the study period: 407 UTIs (397 cases were urinary catheter-associated), 204 BSIs (182 were central line-associated), and 235 PNEUs (161 were ventilator-associated). The rate of urinary catheter-associated UTIs was 4.61 cases per 1,000 device-days and urinary catheter utilization ratio was 0.83. The rate of central line-associated BSIs was 3.16 and the utilization ratio was 0.55. The rate of ventilator-associated PNEUs was 3.80 and the utilization ratio was 0.41. Although the ventilator utilization ratio was lower in the hospitals with 400-699 beds than in the hospitals with more than 900 beds, the rate of ventilator-associated pneumonia was higher in the smaller hospitals than in the larger ones. The rates of all three device-associated infections were the highest in the neurosurgical ICUs and the rates were the lowest in the surgical ICUs. CONCLUSION: This study may contribute to the development of effective strategies for NI control according to the size of hospital and the type of ICUs.

Genetic Diversity among Virulent Mega Plasmids pXO1 and pXO2 of Bacillus anthracis Isolated in Korea

We compared genetic variations in virulence mega plasmids pXO1 and pXO2 of twenty-seven Bacillus anthracis strains from Korean patients and environmental samples together with those of Bacillus anthracis Sterne, Pasteur and A2012 standard strains. Genetic variations were analyzed in twenty-three variable regions (ten and thirteen variablenumber tandem repeats and insertion/deletions in pXO1 and pXO2, respectively). The pXO1 plasmids were classified into 7 groups and pXO2 plasmids to 12 groups. Discrete phylogenic lineages could be differentiated between environmental and clinical strains by UPGMA (unweighted pair group method with average) method. In addition, clinical strains showed more variations than environmental isolates. The pXO2 plasmid appeared genetically more unstable than pXO1. A general plasmid genotype could be suggested for Korean soil isolates since they mostly clustered into a representative group.

Molecular Analysis of Clostridium difficile Isolates by Arbitrarily Primed-Polymerase Chain Reaction and Polymerase Chain Reaction-Ribotyping / 감염

BACKGROUND: Clostridium difficile is known as the major cause of nosocomially acquired diarrhea. Various phenotypic and genotypic methods have been used to subtype C. difficile strains. The purpose of the present study is to evaluate several typing methods which can be used as tools for subtyping C. difficile isolates for epidemiological studies. METHODS: In two Korean tertiary care hospitals, a total of 81 C. difficile isolates were collected from symptomatic, hospitalized patients in 1998. All isolates were examined for the release of toxin A and toxin B by PCR assay and cell culture assay. Also arbitrarily primed-PCR and PCR-ribotyping profiles were determined for the typing of C. difficile strains on a genetic level. RESULTS: The toxin B gene was detected in 65.4% (54/81) of isolates by both PCR assay and cell cultureassay. Nine types were identified with T-7 primer, and 13 types were identified with PG-05 primer in AP- PCR. Sixteen types were identified in PCR-ribotyping. When two typing methods were compared, reproducibility by PCR-ribotyping was 100%, while it was only 83% and 33% AP-PCR with primer T-7, and PG-05, respectively. The discrimination index was 0.88 for PCR-ribotyping, 0.82 for AP-PCR with primer T-7 and 0.81 with primer PG-05. CONCLUSION: These data suggest that PCR-ribotyping provides a reproducible, discriminatory, and simple alternative to conventional molecular approaches for typing strains of C. difficile.

Antimicrobial Resistance of Neisseria gonorrhoeae Isolated in Korea / 감염

BACKGROUND: The aim of this study was to monitor trends in antimicrobial susceptibilities of Neisseria gonorrhoeae isolates, in particular, to examine the possibility of increasing prevalence of fluoroquinolone resistance in Korea and the relationship between patterns of mutations involving gyrA and parC genes and the ciprofloxacin resistance level. METHODS: The antimicrobial susceptibilities of 489 gonoccocal isolates which were nationwide collected from patients visiting Health Centers were determined by NCCLS disk diffusion and agar plate dilution methods. PCR and direct DNA sequencing of the amplicons were performed to identify mutations within the quinolone resistance-determining regions of gyrA and parC genes. RESULTS: The proportion of resistance to penicillin, tetracycline, or both remained as high as 94%. The isolates with ciprofloxacin resistance remarkably increased from 1% in 1999 to 5% in 2000 and also resistance to cefoxitine and ceftriaxone were shown to be increased. The strains resistant to spectinomycin was little reported. Four isolates with 16 microgram/mL of MIC for ciprofloxacin all showed the same alternations of Ser-91 to Phe, Asp-95 to Gly in GyrA and Ser-87 to Arg in ParC, but ciprofloxacin-susceptible strains have little amino acid substitution. CONCLUSION: Considering the increasing prevalence of isolates with resistance to ciprofloxacin and ofloxacin, it is likely that the antibiotics such as spectinomycin, or ceftriaxone are recommended as the first-line treatment for gonoccocal infections in Korea. The results from this study suggest that mutation analysis for quinolone resistance-determining regions of gyrA and parC genes are important in epidemiological studies for the spread of ciprofloxacin resistant strains.

Inflammatory Reaction in Intestinal Mucosa by Bacteroides fragilis Enterotoxin Stimulation: Regulation of Chemokine Gene Expression in Human Intestinal Epithelial Cells

No abstract available.

Emerging antimicrobial resistance, plasmid profile and pulsed-field gel electrophoresis pattern of the endonuclease-digested genomic DNA of Neisseria gonorrhoeae

Resistant gonococci are very prevalent in many countries, particularly in Asia. This study was conducted to determine the trend of resistance, the effect of decreasing the ciprofloxacin susceptibilities of gonococci on the prevalence of penicillinase-producing N. gonorrhoeae (PPNG), and to compare the epidemiology of strains with the previous studies. A total of 602 strains of gonococci were isolated from prostitutes in 1997-1999. Antimicrobial susceptibility was tested by NCCLS disk diffusion and agar dilution methods. For epidemiologic analysis, vplasmid analysis and pulsed-field gel electrophoresis (PFGE) were performed. The proportion of PPNG remained high (79%), and the strains with decreased susceptibility to ciprofloxacin increased significantly from 67% in 1997 to 84% in 1999. Compared to our previous study, the PFGE patterns were similar, while the proportion of strain with the 3.2-MDa plasmid markedly decreased. In conclusion, a rapid increase in ciprofloxacin-nonsusceptible strains may suggest difficulties in the treatment of gonococcal infections in the near future with the drug. The recent decrease of PPNG with the 3.2-MDa plasmid may suggest that there is an epidemiological change in gonococcal infections, and the prevalence of related PFGE patterns suggests the dissemination of a few clones among the high risk populations.

Basolaterial Secretion of CXC Chemokines by Human Intestinal Epithelial Cells in Response to Bacteroides fragilis Enterotoxin Via NF-kB Pathway

No Abstract Available.

Basolaterial Secretion of CXC Chemokines by Human Intestinal Epithelial Cells in Response to Bacteroides fragilis Enterotoxin Via NF-kB Pathway

No Abstract Available.

Prevalence of Leptospira interrogans in Wild Rodents in Korea

Leptospirosis has been known as endemic disease in Korea since 1984. Wild rodent, mostly Apodemus agrarius, has been known as an important source of leptospiral infection especially in rainy circumstances in harvest reason of rural area. The infection rates of Leptospira interrogans in field rodents, Apodemus agrarius, was investigated by culture and PCR detection of leptospiral DNA, and compared with previous data. Furthermore, the serogroup and serovar were investigated. Two hundred twenty two Apodemus agrarius were captured during October to December 1996. Spirohaetes were isolated from 22 (9.9%) and leptospiral DNA was detected in an additional six rodents (12.6%). Subsequent cross-agglutinin absorption test, monoclonal antibody reactivity classified 21 cultures among 22 isolates as Leptospira interrogans serogroup Icterohemorrhagiae serovar lai. The above data did not differ from previous survey in 1984 to 1987. There was no significant change of Leptospira interrogans infection in field rodents in Korea.

Serovar Identification and Genetic Characterization of Leptospira Isolates by Arbitrarily Primed PCR and Ribotyping

Serovars of 22 leptospiral field isolates from rats trapped in Korea were identified by cross-agglutinin absorption test (CAAT). Genomic characteristics of 7 selected isolates and 6 antigenically closely related reference serovars of lai, yeonchon, birkini, gem, mwogolo, and canicola were differentiated by arbitrarily primed PCR (AP-PCR) and southern blot hybridization using 16S rRNA gene probe from Borrelia burgdorferi. Among the 22 isolates, 21 strains were identified as serovar lai by CAAT, while the serological reactivity of NR13 did not accord with that of serovar lai. Results of AP-PCR using primers RSP, KF and PB-1 were in general agreement with those obtained by serological identification, and all 7 isolates including NR13 showed the same profile with serovar lai or yeonchon. In the southern blot hybridization with 16S rRNA gene probe, the isolates were divided into two ribotype groups when HindIII and BamHI digests were employed: isolates NR4, NR13, and serovar lai showed the same profile, and isolates JR34, JR57, KR48, JR77, and JR82 were classified as the another ribotype group. Isolate NR13 and serovar yeonchon, which were isolated in Korea and showed serological differences with serovar lai, were indistinguishable from serovar lai in this DNA study using AP-PCR and ribotyping. These results demonstrate that Korean leptospiral isolates were closely related in DNA level, and ribotyping would be useful for subgrouping of field isolates.