Genomic characterization, antimicrobial resistance profiles, enterotoxin, and biofilm production of methicillin-resistant Staphylococcus aureus isolated from clinical and animal products origins in Eastern Turkey / Caracterização genômica perfis de resistência antimicrobiana, produção de enterotoxinas e biofilme Staphylococcus aureus resistente à meticilina isolado de origem clínica e de produtos de origem animal no leste da Turquia

Staphylococcus aureus is an opportunistic and ubiquitous pathogen found in the skin, nares, and mucosal membranes of mammals. Increasing resistance to antimicrobials including methicillin has become an important public concern. One hundred and eight (108) S. aureus strains isolated from a total of 572 clinical and animal products samples, were investigated for their biofilm capability, methicillin resistance, enterotoxin genes, and genetic diversity. Although only one strain isolated from raw retail was found as a strong biofilm producer, the percentage of antimicrobial resistance pattern was relatively higher. 17.59% of S. aureus strains tested in this study were resistant to cefoxitin and identified as methicillin-resistant S. aureus (MRSA) isolates. mecA and mecC harboring S. aureus strains were detected at a rate of 2.79% and 0.93%, respectively. In addition, staphylococcal enterotoxin genes including Sea, Seb, Sec, and Sed genes were found to be 18.5%, 32.4%, 6.5% and 3.7%, respectively. The phylogenetic relationship among the isolates showed relationship between joint calf and cow milk isolates. Multi locus sequence typing (MLST) revealed three different sequence types (STs) including ST84, ST829, and ST6238. These findings highlight the development and spread of MRSA strains with zoonotic potential in animals and the food chain throughout the world.

Staphylococcus aureus é um patógeno dúctil e ubíquo encontrado na pele, narinas e membranas mucosas de mamíferos. O aumento da resistência aos antimicrobianos, incluindo a meticilina, tornou-se uma importante preocupação pública. Cento e oito (108) cepas de S. aureus isoladas de um total de 572 amostras clínicas e de produtos animais foram investigadas por sua capacidade de biofilme, resistência à meticilina, genes de enterotoxinas e diversidade genética. Embora apenas uma cepa isolada do cru tenha sido encontrada como forte produtora de biofilme, a porcentagem do padrão de resistência antimicrobiana foi relativamente maior. Parte das cepas (17,59%) de S. aureus testadas neste estudo eram resistentes à cefoxitina e identificadas como isolados de MRSA. mecA e mecC abrigando cepas de S. aureus foram detectados a uma taxa de 2,79% e 0,93%, respectivamente. Além disso, verificou-se que os genes da enterotoxina estafilocócica, incluindo os genes Sea, Seb, Sec e Sed, eram 18,5%, 32,4%, 6,5% e 3,7%, respectivamente. A relação filogenética entre os isolados mostrou relação entre os isolados de bezerro e leite de vaca. A tipagem de sequência multiloco (MLST) revelou três tipos de sequência diferentes (STs), incluindo ST84, ST829 e ST6238. Essas descobertas destacam o desenvolvimento e a disseminação de cepas de MRSA com potencial zoonótico em animais e na cadeia alimentar em todo o mundo.

Genomic characterization, antimicrobial resistance profiles, enterotoxin, and biofilm production of methicillin-resistant Staphylococcus aureus isolated from clinical and animal products origins in Eastern Turkey

ABSTRACT: Staphylococcus aureus is an opportunistic and ubiquitous pathogen found in the skin, nares, and mucosal membranes of mammals. Increasing resistance to antimicrobials including methicillin has become an important public concern. One hundred and eight (108) S. aureus strains isolated from a total of 572 clinical and animal products samples, were investigated for their biofilm capability, methicillin resistance, enterotoxin genes, and genetic diversity. Although only one strain isolated from raw retail was found as a strong biofilm producer, the percentage of antimicrobial resistance pattern was relatively higher. 17.59% of S. aureus strains tested in this study were resistant to cefoxitin and identified as methicillin-resistant S. aureus (MRSA) isolates. mecA and mecC harboring S. aureus strains were detected at a rate of 2.79% and 0.93%, respectively. In addition, staphylococcal enterotoxin genes including Sea, Seb, Sec, and Sed genes were found to be 18.5%, 32.4%, 6.5% and 3.7%, respectively. The phylogenetic relationship among the isolates showed relationship between joint calf and cow milk isolates. Multi locus sequence typing (MLST) revealed three different sequence types (STs) including ST84, ST829, and ST6238. These findings highlight the development and spread of MRSA strains with zoonotic potential in animals and the food chain throughout the world.

RESUMO: Staphylococcus aureus é um patógeno dúctil e ubíquo encontrado na pele, narinas e membranas mucosas de mamíferos. O aumento da resistência aos antimicrobianos, incluindo a meticilina, tornou-se uma importante preocupação pública. Cento e oito (108) cepas de S. aureus isoladas de um total de 572 amostras clínicas e de produtos animais foram investigadas por sua capacidade de biofilme, resistência à meticilina, genes de enterotoxinas e diversidade genética. Embora apenas uma cepa isolada do cru tenha sido encontrada como forte produtora de biofilme, a porcentagem do padrão de resistência antimicrobiana foi relativamente maior. Parte das cepas (17,59%) de S. aureus testadas neste estudo eram resistentes à cefoxitina e identificadas como isolados de MRSA. mecA e mecC abrigando cepas de S. aureus foram detectados a uma taxa de 2,79% e 0,93%, respectivamente. Além disso, verificou-se que os genes da enterotoxina estafilocócica, incluindo os genes Sea, Seb, Sec e Sed, eram 18,5%, 32,4%, 6,5% e 3,7%, respectivamente. A relação filogenética entre os isolados mostrou relação entre os isolados de bezerro e leite de vaca. A tipagem de sequência multiloco (MLST) revelou três tipos de sequência diferentes (STs), incluindo ST84, ST829 e ST6238. Essas descobertas destacam o desenvolvimento e a disseminação de cepas de MRSA com potencial zoonótico em animais e na cadeia alimentar em todo o mundo.

Phenotypic and molecular detection of metallo-ß-lactamase-producing Pseudomonas aeruginosa isolates from patients with burns in Tehran, Iran

Abstract INTRODUCTION: Health care-associated infections caused by metallo-β-lactamase (MBL)-producing Pseudomonas aeruginosa are a significant growing concern in patients with burns worldwide. The aims of this study were to determine the antibiotic susceptibility of and detect the presence of MBLs among P. aeruginosa isolates and assess their clonal relationship using enterobacterial repetitive intergenic consensus (ERIC)-PCR. METHODS: Non-duplicated clinical isolates (160) of P. aeruginosa were collected from patients with burns at the Motahari Hospital in Tehran, Iran. All isolates were identified using standard laboratory methods and further characterized for antimicrobial susceptibility. Any carbapenem-resistant isolates were then examined for MBL production by the E-test and MBL-encoding genes were detected by PCR. The clonal relatedness of MBL-producing isolates was assessed by ERIC-PCR. RESULTS: For multidrug-resistant isolates, the highest rates of susceptibility were observed for colistin 160 (100%), polymyxin B 160 (100%), and ceftazidime 32 (20%). In total, 69 (43.7%) isolates were identified as MBL producers. Twenty-eight (17.5%) isolates were positive for the bla VIM-1 gene followed by the bla IMP-1 (15.6%) and bla SPM-1 (5.6%) genes. ERIC-PCR revealed three separate genotypes, where type A (76.8%) was the most prevalent, followed by B (20.3%), and then C (2.9%). CONCLUSIONS: Our present study found that the bla IMP-1 and bla VIM-1 genes were present at a significant frequency and also detected the bla SPM-1 gene in P. aeruginosa isolates for the first time, highlighting the need for establishing suitable infection control measures to successfully treat patients and prevent further spread of these resistant organisms among patients with burns.

Genotypic Diversity of Multidrug Resistant Shigella species from Iran / 감염과화학요법

BACKGROUND: In many developing countries, shigellosis is endemic and also occurs in epidemics and treatment of multidrug-resistant (MDR) isolates are important. The aims of this study were to determine the antimicrobial susceptibility, prevalence of class 1 and 2 integrons and the clonal relatedness of isolates. MATERIALS AND METHODS: Antimicrobial susceptibility tests were performed by disc diffusion method. Polymerase chain reaction (PCR)-sequencing technique was employed for detection and characterization of integrons. The genetic relatedness was evaluated by using enterobacterial repetitive intergenic consensus (ERIC) PCR. RESULTS: There was a high percentage of resistance to trimethoprim-sulfamethoxazole (TMP/SMX) (93.7%), ampicillin (AMP) (87.3%), streptomycin (STR) (84.5%) and tetracycline (TET) (78.9%). Multidrug resistant phenotype was seen in 95.1% of total isolates. Most common MDR profile was TMP/SMX/STR/AMP resistant pattern. Among the 142 Shigella spp. analyzed in this study, 28 isolates were positive for class 1 integron with two types of gene cassette arrays (dfrA17/aadA5 = 31.7% and dfrA7 = 3.8%). The class 2 integron was more frequently detected among the isolates (94.7%) with dfrA1/sat1/aadA1 (69.4%) and dfrA1/sat1 (30.6%) gene cassettes. ERIC-PCR results showed 6, 5, 4 and 3 main genotypes among S. flexneri, S. sonnei, S. boydii and S. dysenteriae isolates, respectively. CONCLUSIONS: Our findings revealed that multidrug resistant Shigella species with high prevalence of class 2 integron were very common in Iran. In addition, ERIC-PCR patterns showed limited variety of clones are responsible for shigellosis in the region of the study.

Genotypic Diversity of Multidrug Resistant Shigella species from Iran / 감염과화학요법

BACKGROUND: In many developing countries, shigellosis is endemic and also occurs in epidemics and treatment of multidrug-resistant (MDR) isolates are important. The aims of this study were to determine the antimicrobial susceptibility, prevalence of class 1 and 2 integrons and the clonal relatedness of isolates. MATERIALS AND METHODS: Antimicrobial susceptibility tests were performed by disc diffusion method. Polymerase chain reaction (PCR)-sequencing technique was employed for detection and characterization of integrons. The genetic relatedness was evaluated by using enterobacterial repetitive intergenic consensus (ERIC) PCR. RESULTS: There was a high percentage of resistance to trimethoprim-sulfamethoxazole (TMP/SMX) (93.7%), ampicillin (AMP) (87.3%), streptomycin (STR) (84.5%) and tetracycline (TET) (78.9%). Multidrug resistant phenotype was seen in 95.1% of total isolates. Most common MDR profile was TMP/SMX/STR/AMP resistant pattern. Among the 142 Shigella spp. analyzed in this study, 28 isolates were positive for class 1 integron with two types of gene cassette arrays (dfrA17/aadA5 = 31.7% and dfrA7 = 3.8%). The class 2 integron was more frequently detected among the isolates (94.7%) with dfrA1/sat1/aadA1 (69.4%) and dfrA1/sat1 (30.6%) gene cassettes. ERIC-PCR results showed 6, 5, 4 and 3 main genotypes among S. flexneri, S. sonnei, S. boydii and S. dysenteriae isolates, respectively. CONCLUSIONS: Our findings revealed that multidrug resistant Shigella species with high prevalence of class 2 integron were very common in Iran. In addition, ERIC-PCR patterns showed limited variety of clones are responsible for shigellosis in the region of the study.

High prevalence of plasmid-mediated quinolone resistance determinants in Enterobacter cloacae isolated from hospitals of the Qazvin, Alborz, and Tehran provinces, Iran

Abstract: INTRODUCTION: Plasmid-mediated quinolone resistance (PMQR) is a growing clinical concern worldwide. The main aims of this study were to detect qnr-encoding genes and to evaluate the clonal relatedness of qnr-positive Enterobacter cloacae isolates. METHODS: A total of 116 E. cloacae isolates that were not susceptible to quinolone were obtained from seven hospitals in Tehran, five hospitals in Qazvin, and two hospitals in Karaj (Iran). Bacterial identification was performed using standard laboratory methods and API 20E strips. Quinolone resistance was determined using the Kirby-Bauer disk diffusion method according to the Clinical Laboratory Standards Institute (CLSI) guidelines. PCR and sequencing were employed to detect qnrA, qnrB, and qnrS genes, and clonal relatedness was assessed using the enterobacterial repetitive intergenic consensus (ERIC)-PCR method. RESULTS: In total, 45 (38.8%) and 71 (61.2%) of isolates showed high- and low-level quinolone resistance, respectively, and qnr-encoding genes were detected in 70 (60.3%) of them. qnrB1 [45 (38.8%) isolates] was the most commonly detected gene, followed by qnrS1 [28 (24.1%) isolates] and qnrB4 [18 (15.5%) isolates] either alone or in combination with other genes. The results of the ERIC-PCR revealed that 53 (75.7%) qnr-positive isolates were genetically unrelated. CONCLUSIONS: This study describes, for the first time, the high prevalence of the qnrB1, qnrS1, and qnrB4 genes among E. cloacae isolates in Iran. The detection of qnr genes emphasizes the need for establishing tactful policies associated with infection control measures in hospital settings in Iran.

Molecular epidemiological characteristics of metallo-β-lactamase-producing Pseudomonas aeruginosa from Changsha / 中国感染控制杂志

Objective To investigate the genotypes and epidemic of metallo-β-lactamase-(MBL )-producing Pseudomonas aeruginosa (P .aeruginosa)in Changsha.Methods P .aeruginosa isolated from seven comprehensive hospitals in Changsha were collected and performed identification and antimicrobial susceptibility testing,pheno-types of MBL were detected with EDTA-disk synergy test and E-test,genotypes were determined by polymerase chain reaction (PCR),homology analysis were conducted by enterobacterial repetitive intergenic consensus PCR (ERIC-PCR).Results Preliminary screening by EDTA-disk synergy test and E-test showed that only 10 of 81 iso-lates were strong positive;PCR result showed that 18 isolates were positive for MBL,11 of which were IMP-9-type MBL,1 was IMP-1-type,and 6 were VIM-2-type.SIM,SPM,GIM,and NDM-1-types were not found.ERIC-PCR showed that 12 strains of IMP-producing P .aeruginosa has multiple types,6 VIM-2-producing strains were of the same type.Conclusion IMP-9 and VIM-2 are main genotypes in P .aeruginosa in Changsha.

A study of outer membrane protein and molecular epidemiology of carbapenem-resistantAcinetobacter baumannii / 中华危重病急救医学

ObjectiveTo study the characteristics of the distribution and drug resistance ofAcinetobacter baumannii, and the epidemiology of the main strains among wards and hospitals, and to investigate the role of outer membrane protein in producing resistance against carbapenems.Methods 145Acinetobacter baumannii strains were collected from July 2013 to July 2014 from Huangdao Hospital Affiliated to Qingdao University and 401st Army Hospital. Antimicrobial susceptibility test was carried out with K-B disk diffusion method. Enterobacterial repetitive intergenic consensus polymerase chain reaction (ERIC-PCR) was used for DNA typing and test of homology. The carO gene of outer membrane protein was amplified by PCR, and the outer membrane proteins were extracted by ultrasonication and ultracentrifuge method from 30 randomly selected carbapenem-resistantAcinetobacter baumannii and 17 carbapenem-sensitive strains. Sodium dodecyl sulfate-polyacrylamide gel electropheresis (SDS-PAGE) was used to analyze the expressions of outer membrane proteins.Results 145Acinetobacter baumannii strains were generally resistant to 16 common antimicrobial agents, with the highest susceptibility rate of 79.3% for minocycline, followed by susceptibility rate of 40.7% for amikacin. There were 128 carbapenem-resistant strains (resistance rate of 88.3%), 137 multidrug-resistant strains and 126 extensively drug-resistant strains. The detection rates of carO gene were 97.7%(125/128)and 17.6%(3/17) in carbapenem-resistant and sensitive strains respectively. Around position of relative molecular mass 47 000, 16 of 17 sensitive isolates were expressed this protein, while 20 of 30 resistant ones were detected nothing or fade; 13 of 17 sensitive isolates were expressed around position of relative molecular mass 37 000 and 29 000 while 25 were detected nothing or fade around position of relative molecular mass 37 000 and 23 were detected nothing or fade around position of relative molecular mass 29 000 in 30 resistant ones. 145Acinetobacter baumannii were classified into 8 types based on ERIC-PCR electrophoresis patterns, and the major prevalence types were type A (71 strains) and type E (37 strains).Conclusions Drug resistance of clinically isolatedAcinetobacter baumannii is a serious problem in two hospitals; drug-resistant strains are spread and epidemic among wards and hospitals. The carO gene of outer membrane protein is widespread in carbapenem-resistantAcinetobacter baumannii. The loss or fading of outer membrane protein may play an important role inAcinetobacter baumannii resistance to carbapenems drugs.

Preliminary study of intestinal flora distribution in infants with different feeding patterns / 中华实用儿科临床杂志

Objective To investigate the characteristics of intestinal flora in infants with different feeding patterns.Methods Sixty-two cases of health infants(30-120 d)were divided into 4 groups according to their feeding patterns:breast feeding,imported powder milk feeding,domestic powder milk feeding and mixed feeding.Samples of their fresh feces in each group were collected and divided into sections equally:the bifidobacteria were isolated in anaerobic box and the number was counted for one section;for the other section,total DNA of intestinal flora was extracted and enterobacterial repetitive intergenic consensus (ERIC) fingerprints were amplified with the method of ERIC-PCR.After that,the specific bands observed in different groups were cloned and sequenced and alignmented.Results The colonies of bifidobacteria were more in breast feeding and mixed feeding groups[(9.10 ± 1.33) cfu/g;(8.62 ± 1.35) cfu/g]than those in domestic powder milk feeding and imported powder milk feeding groups[(7.62 ± 1.22) cfu/g;(7.32 ± 0.80) cfu/g,t =3.23,P ＜ 0.05];while there was no significant difference between breast feeding and mixed feeding groups,and between 2 powder milk feeding groups.Two specific bands were found from the ERIC fingerprints (A:1 100 bp mainly in breast feeding,domestic powder milk feeding and mixed feeding groups;B:1 000 bp mainly in imported powder milk feeding group).Sequencing and analysis of Basic Local Alignment Search Tool showed that homologous bacteria of A and B fragments were bifidobacterium longum.The encoding protein of A fragments might be related to the enzymes of carbohydrate metabolism,and B fragments were related to the enzymes of protein metabolism.Conclusions The colonies of bifidobacteria in intestinal tract are more in breast feeding and mixed feeding infants than those in formula feeding groups.The distribution of intestinal flora in domestic powder milk feeding infants is more similar to that of the breast feeding infants.

Carbapenemase genes and homology of Acinetobacter baumannii in two hospitals of Qingdao / 中国感染控制杂志

Objective To investigate antimicrobial resistance,distribution,and carriage of carbapenemase genes of Acinetobacterbaumannii(AB)from two hospitals in Qingdao.Methods 145 AB isolates collected from two hospi-tals (78 from hospital A,67 from hospital B)were performed antimicrobial susceptibility testing,carbapenemase genes were amplified by polymerase chain reaction (PCR);homology analysis were conducted with enterobacterial repetitive intergenic consensus (ERIC)-PCR.Results AB from hospital A were generally resistant to 16 commonly used antimicrobial agents,with the lowest resistant rate of 3.85% to cefoperazone/sulbactam,followed by resist-ance rate of 16.67% to minocycline,resistant rates to the other antimicrobial agents were all>73% . AB from hos-pital B were generally resistant to 23 commonly used antimicrobial agents,but the resistance rates to minocycline and tigecycline were both 0,resistance rates to amikacin and levofloxacin were 23.88% and 38.81% respectively, resistant rates to the other antimicrobial agents were all >64% . All strains carried OXA-5 1 gene,the carriage rates of OXA-23 gene in carbapenem-resistant group were 86.76% (59/68)and 56.67% (34/60)in hospital A and B re-spectively,the difference was significant(χ2= 14.53,P<0.001);OXA-58 gene was detected in 3 isolates in hospi-tal A but not detected from hospital B. 145 AB strains were classified into 8 types,the major prevalence types were type A (n= 71)and E(n= 37);the major prevalence types in hospital A were type A (46.15% )and E(41.03% ), hospital B were type A (52.24% )and C (17.91% ).Conclusion Antimicrobial resistance of clinically isolated AB is serious and prevailed in two hospitals. OXA-23 and OXA-51 genes play an important role in AB resistance to car-bapenems.

Enterobacterial repetitive intergenic consensus-polymerase chain reaction typing of Escherichia coli isolated from hospitalized neonates / 中华实用儿科临床杂志

Objective To explore the genetic relationship among the isolates of Escherichia coli,and to analyze the epidemiological status.Methods One hundred and ten strains of Escherichia coli were isolated from 102 hospitalized neonates in the Neonatal Center of Beijing Children's Hospital.The homologous relation among the strains were typed and studied by using enterobacterial repetitive intergenic consensus-polymerase chain reaction (ERIC-PCR) method.Results One hundred and two cases of neonates were selected,including 61 male cases and 41 female cases.Among them,94 cases were full-term infants,8 cases were preterm infants,25 cases ≤7 days,and 77 cases ＞ 7 days.One hundred and ten strains of Escherichia coli isolated clinically by ERIC-PCR typing were divided into 58 types,fingerprints indnded 4-12 bands,and the similarity coefficient was between 26.2％ and 100.0％.The dominant genotype contained 6 strains,with 4-5 bands,and the similarity coefficient was 88.9％-100.0％.In dominant genotype E58,5 out of 6 strains were attacked in March,and 1 strain attacked by the end of February.In the second dominant type E32,4 out of 5 strains were spread in May,and 1 strain in July.In E23 type,4 out of 5 strains were distributed in September,and 1 strain in October.There were 8 pairs of clinical isolates from 8 neonatal patients,including 7 pairs of them belonging to the same genotype,and the other 1 pair of isolates did not belong to the same genotype and was distantly related.From homology analysis point of view,the possibility of the different isolates was infectious or contaminant.Two strains were isolated from the blood and cerebrospinal fluid of the same patient,belonging to the same genotype,with 100.0％ similarity coefficient.Five isolates were confirmed to have closer relationship by ERIC-PCR genotyping.One isolate derived from a child and the other 4 isolates derived from the other 4 children were considered hospital-acquired infection since these five children shared one ward.Conclusions Escherichia coli infections in full-term infants are more common.Most of them are late infections,and boys are more than girls.Different seasons may have different types of epidemic caused by Escherichia coli infection of respiratory tract.Strains of high homology hospital-acquired infection by Escherichia coli was found at Beijng Children's Hospital had Escherichia coli hospital-acquired infection.ERIC-PCR typing method can track the source of infection,which plays a role in prevention and control of nosocomial infection.

Epidemiological characterization of resistance and PCR typing of Shigella flexneri and Shigella sonnei strains isolated from bacillary dysentery cases in Southeast Brazil

Shigella spp are Gram-negative, anaerobic facultative, non-motile, and non-sporulated bacilli of the Enterobacteriaceae family responsible for "Shigellosis" or bacillary dysentery, an important cause of worldwide morbidity and mortality. However, despite this, there are very few epidemiological studies about this bacterium in Brazil. We studied the antibiotic resistance profiles and the clonal structure of 60 Shigella strains (30 S. flexneri and 30 S. sonnei) isolated from shigellosis cases in different cities within the metropolitan area of Campinas, State of São Paulo, Brazil. We used the following well-characterized molecular techniques: enterobacterial repetitive intergenic consensus, repetitive extragenic palindromic, and double-repetitive element-polymerase chain reaction to characterize the bacteria. Also, the antibiotic resistance of the strains was determined by the diffusion disk method. Many strains of S. flexneri and S. sonnei were found to be multi-resistant. S. flexneri strains were resistant to ampicillin in 83.3 percent of cases, chloramphenicol in 70.0 percent, streptomycin in 86.7 percent, sulfamethoxazole in 80.0 percent, and tetracycline in 80.0 percent, while a smaller number of strains were resistant to cephalothin (3.3 percent) and sulfazotrim (10.0 percent). S. sonnei strains were mainly resistant to sulfamethoxazole (100.0 percent) and tetracycline (96.7 percent) and, to a lesser extent, to ampicillin (6.7 percent) and streptomycin (26.7 percent). Polymerase chain reaction-based typing supported the existence of specific clones responsible for the shigellosis cases in the different cities and there was evidence of transmission between cities. This clonal structure would probably be the result of selection for virulence and resistance phenotypes. These data indicate that the human sanitary conditions of the cities investigated should be improved.

Emergence of CTX-M-9 Extended-Spectrum beta-Lactamase-Producing Enterobacter cloacae Isolates / 대한임상미생물학회지

BACKGROUND: The aim of this study is to assess the prevalence and to investigate the molecular epidemiology of Ambler class A extended-spectrum beta-lactamase (ESBL)-producing Enterobacter cloacae isolates in a university hospital in Busan, Korea. METHODS: Non-duplicated clinical isolates of E.cloacae from patients admitted in Kosin University Gospel Hospital were collected during the period from January through September, 2003. ESBL-production was examined by the double-disk synergy test (DDST) and the transferability of cefotaxime-resistance by conjugation. MICs of beta-lactam antibiotics were determined by the agar dilution method and Ambler class A ESBL genes were searched by PCR amplification. Enterobacterial repetitive intergenic consensus (ERIC) PCR was performed to investigate epidemiological relationships among bla CTX-M-9 gene-carrying E.cloacae isolates. RESULTS: Antimicrobial resistance rates of E.cloacae isolates (n=148) to ceftazidime, cefotaxime, and aztreonam were 50.0%, 29.6%, and 48.0%, respectively. Among 50 E.cloacae isolates intermediate or resistant to more than one expanded-spectrum beta-lactam agent, 41 (27.7%) showed positive results in DDST; of these 41 isolates, 1 was found to carry bla TEM-52 gene, 16 carried bla SHV-12 gene, 4 bla CTX-M-9 gene, and 19 both bla SHV-12 and bla CTX-M-9 genes. The 23 E.cloacae isolates carrying bla CTX-M-9 gene showed 9 different profiles by ERIC PCR. CONCLUSION: ESBL-producing E.cloacae was not uncommon in a university hospital in Busan, Korea. The commonest types of ESBLs produced by E.cloacae isolates were SHV-12 and CTX-M-9. CTX-M-9 ESBL-producing E.cloacae isolates showed diverse ERIC-PCR profiles, indicating that they were not originated from a common source.