No abstract available.
R Factors* ; Shigella*

The study was performed on 90 Salmonella typhi strains isolated from patients in Hanoi, Hue and Ho Chi Minh city. The results showed that: the multi-antibiotic resistant Salmonella typhi strains have already spread over the country; 2 plasmid with size about 120 kilobase (Kb) and 102 Kb. Plasmid 120 Kb is conjugated, self-transmitted R-plasmid and carrying at least 5 antibiotic resistant genes to chloramphenicol, ampicillin, tetracycline and trimethoprim/sulfamethoxazole. The initial analysis by a restricted enzyme of EcoRi showed that these self-transmitted R-plasmid in S.typhi strains isolated in 3 areas Hanoi, Hue and Hochiminh city maybe the same origin.
Salmonella typhi ; R Factors ; epidemiology

Forty-seven ampicillin-resistant R plasmids derived from 218 Shigella sonnei isolates from Daegu and Gwangju areas from 1980 to 2000 were epidemiologically compared by fragments of restriction endonuclease patterns by EcoRI and SmaI, and by Southern hybridization with a blaTEM-1 probe. All the ampicillin-resistant strains isolated in the 1980S carried a conjugative R plasmid responsible for multiple resistance other than ampicillin, and an ampicillin-resistance plasmid. Ampicillin-resistant strains isolated in the 1990S harbored single conjugative R plasmid encoding ampicillin resistance along with variable antimicrobial resistances. The restriction endonuclease digestion patterns and Southern hybridiztion analysis of conjugative R plasmids showing identical resistance pattern and a same size showed different fragment and Western blotting patterns according to different isolation years and areas, while identical patterns were observed among the plasmids derived from a same isolation year and area. These findings suggest that ampicillin resistance among S. sonnei isolates was due to introduction of ampicillin-resistant R plasmids originated from different sources.
Ampicillin Resistance* ; Ampicillin* ; Blotting, Western ; Daegu ; Digestion ; DNA Restriction Enzymes ; Gwangju ; Plasmids ; R Factors ; Shigella sonnei* ; Shigella*

One hundred and eighteen strains of Escherichia coli isolated from clinical specimens were epidemiologically analyzed for antimicrobial resistance, EcoRI restriction endonuclease analysis, southern hybridization with TEM and SHV probe of conjugative R plasmids. 1. Sixty-two to 73% of E. coli isolates were resistant to ampicillin, carbenicillin, sulfisomidine, and tetracycline, and 20-27% to kanamycin, gentamicin, tobramycin, and nalidixic acid. However more than 93% were susceptible to cephalosporins and all strains were highly susceptible to cefotetan, imipenem, aztreonam, and amikacin. 2. Twelve strains were susceptible to all drugs tested and the multiple resistant strains showed 65 resistance pattern types. 3. Thirty-six resistant strains(34%) transferred R plasmids to E. coli RG488 or RG176 by mixed culture. Fifty-six plasmids with 31 different resistant phenotype were obtained from them. 4. Some of 15 plasmids derived from 10 strains showed identical or similar EcoRI restriction endonuclease digestion patterns, hybridized fragment patterns with TEM probe by southern hybridization, and resistance levels of j3-lactams and aminoglycosides. These results indicate that the epidemic strains or plasmids were present in this hospital and molecular genetic analysis of R plasmids can be used to discriminate clinical isolates of multi- resistant E. coli.
Amikacin ; Aminoglycosides ; Ampicillin ; Aztreonam ; Carbenicillin ; Cefotetan ; Cephalosporins ; Digestion ; DNA Restriction Enzymes ; Escherichia coli* ; Escherichia* ; Gentamicins ; Imipenem ; Kanamycin ; Molecular Biology ; Nalidixic Acid ; Phenotype ; Plasmids ; R Factors ; Sulfisomidine ; Tetracycline ; Tobramycin

One hundred and twenty-two strains of E. coli isolated from urinary tract infection were examined for antibiogram, transferability of trimethoprim (Tp) resistance, incompatibility with F group plasmid and southem hybridization with DHFR I, II, and III probe of Tp-resistant R plasmids. 1. Among 172 Gram negative bacilli isolated from urinary tract infection, 122 (70.9%) were E. coli and 75 strains of them were resistant to trimethoprim (Tp). Most of Tp-resistant isolates were also resistant to penicillins (ampicillin, carbenicillin, and ticarcillin), aminoglycosides (kanamycin and gentamicin), and sulfisoxazole but almost all strains were susceptible to cephalosporins. 2. Most of Tp-resistant strains and E. coli transconjugant derived from them showed multiple drug resistance and various antimicrobial resistance patterns. 3. Thirty-three Tp-resistant strains (45.2%) transferred 35 Tp-resistant plasmids to E. coli recipients but among them 6 transconjugants did not show retransfer of resistance and plasmid DNA were not detected in 2 transconjugants after resistance transfer. 4. Tp-resistant R plasmids ranged from 157 to 67 kb and 8 R plasmids were classified to incompatibilty group IncFI or IncFII ranging from 120 to 83 kb. Three and two R plasmids belonged to IncFII showed similar molecular weight, resistance pattern, and reaction site by southern hybridization with DHFR I probe. Twenty-five plasmids specifically responded on various EcoRI endonuclease fragments to DHFR I probe but not to DHFR II or DHFR III probe. These findings suggest that most of Tp- resistant R plasmids from urine isolates of E. coli were derived from various sources but some plasmids including IncFII R plasmids were probably originated from same or similar sources.
Aminoglycosides ; Carbenicillin ; Cephalosporins ; Deoxyribonuclease EcoRI ; DNA ; Drug Resistance, Multiple ; Escherichia coli* ; Escherichia* ; Microbial Sensitivity Tests ; Molecular Weight ; Penicillins ; Plasmids ; R Factors ; Sulfisoxazole ; Trimethoprim Resistance* ; Trimethoprim* ; Urinary Tract Infections

The frequency of antibiotic resistance among Salmonella enterica serovar Typhimurium has increased due to the transfer of multiple resistance factors. We detected the 13 antibiotic resistance genes by multiplex-PCR and compared with the results of phage typing and antibiotic disk diffusion for 49 S. typhimurium isolated from food-poisoning outbreaks in Seoul from 1999 to 2002. Resistance genes for tetracycline, streptomycin, ampicillin, sulfonamide, amino-glycoside-modifying enzyme, chloramphenicol, kanamycin, and trimethoprim were detected in 67.3%, 57.1%, 26.5%, 8.1%, 8.1%, 5%, 2.0%, and 0% of isolates, respectively. Overall 28 isolates (57.1%) possessed two or more antibiotic resistance genes. Class 1 integron carrying multidrug resistace genes, ant(3")-IaB, blaPSE, qacE delta1/sul, and tet G were amplified especially in only DT104 isolates. Among the related resistance genes for same antibiotics, strA and strB for streptomycin resistance were simultaneously detected but tetA and tetB for tetracycline were sporadically detected. DT 104 isolates contained only aadA2 and tetG.
Ampicillin ; Anti-Bacterial Agents ; Bacteriophage Typing ; Chloramphenicol ; Diffusion ; Disease Outbreaks ; Drug Resistance, Microbial ; Humans ; Integrons ; Kanamycin ; R Factors ; Salmonella enterica* ; Salmonella* ; Seoul* ; Streptomycin ; Tetracycline ; Trimethoprim

Clinical isolates of Enterobacteriaceae (189 Klebsiella, 61 Enterobacter, 32 Serratia, 19 E. coli, 7 Proteus, and 3 Citrobacter) from one university hospital were epidemiologically analyzed by using transferable R plasmids resistant beta-lactam antibiotics including broad-spectrum cephalosporins. About 30% of E. cloacae and S. marcescens and about 5% of K. pneumoniae were resistant to one or more broad-spectrum j3-lactam antibiotics including cefotaxim, ceftazidime, aztreonam, or cefoxitin but all isolates of E. aerogenes, K oxytoca, and P. mirabilis were susceptible. Thirty-six conjugative R plasmids including 8 plasmids resistant expanded-spectrum cephalosporins were obtained from multiple resistant K. pneumoniae (19), E. cloacae (9), E. coli (4), and C. freundii (1). Thirty-one plasmids were subjected to R plasmid analysis and classified 20 different plasmid types. Among them 5, 2, and 2 plasmids belong to 3 different types respectively showed identical molecular size, endonuclease fragment pattern by Southem hybridization pattern by TEM-1 probe, pI value by isoelctric focusing, and also identical antibiogram and biotype of wild strains harboring plasmids. But all of plasmids resistant to cefotaxim, ceftazidime, aztreonam or cefoxitin showed different palsmid anlysis patterns. These results indicate that the epidemic strains of 3 clonal types had been present in this hospital and anlysis using transferable R plasmid and bla gene can be used to discriminate multi-resistant clinical isolates of Enterobacteriaceae.
Anti-Bacterial Agents* ; Aztreonam ; Cefotaxime ; Cefoxitin ; Ceftazidime ; Cephalosporins ; Cloaca ; Dermatoglyphics* ; Enterobacter ; Enterobacteriaceae* ; Klebsiella ; Microbial Sensitivity Tests ; Mirabilis ; Plasmids* ; Pneumonia ; Proteus ; R Factors ; Serratia

Conjugative R plasmids derived from 74 clinical isolates of Serratia marcescens were epidemiologically analyzed for antimicrobial resistance, EcoRI restriction endonuclease analysis and Southern hybridization with DHFR, TEM and SHV probe. 1. Resistance frequency of isolates against various B-lactam antibiotics was changed by year. 2. Twenty (27%) resistant strains transferred 32 R plasmids to E. coli or Klebsiella by mixed culture. Most strains isolated from 1994 to 1996 transferred only trimethoprim resistance but most strains isolated from 1997 did resistances against gentamicin (Gm) and B-lactams including ampicillin (Ap), carbenicillin (Cb), cefazolin (Cz), cefaloridine (Cl), cefamandole (Cn). 3. Ten plasmids of GmApCbCzC1Cn or GmApCbCzC1 pattern and 3 plasmids of TcSuGmTbApCbCzC1 pattern respectively showed identical EcoRI restriction endonuclease digestion patterns and hybridized fragment patterns with TEM-1 probe by Southern hybridization. These results indicate that the epidemic plasmids carrying blamM gene were present in this hospital in 1997 and molecular genetic analysis of R plasmids can be used to discriminate S. marcescens isolates for epidemiologic studies.
Ampicillin ; Anti-Bacterial Agents ; Carbenicillin ; Cefamandole ; Cefazolin ; Cephaloridine ; Digestion ; DNA Restriction Enzymes ; Epidemiologic Studies ; Epidemiology* ; Gentamicins ; Klebsiella ; Molecular Biology ; Plasmids ; R Factors ; Serratia marcescens* ; Serratia* ; Trimethoprim Resistance

One hundred and thirty trimethoprim-resistant R plasmids derived from of Escherichia coli isolated from clinical specimens and feces of healthy collegians were examined for incompatibility, EcoRI endonuclease restriction fragment pattern, and Southern hybridization with DHFR I, II, III, V, and VII probe. 1. Most trimethoprim-resistant R plasmids were resistant to ampicillin, tetracycline, chloramphenicol, gentamicin, and kanamycin, and showed multiple drug resistance and various antimicrobial resistance patterns. 2. Trimethoprim-resistant R plasmids ranged from 90 to 50 kilobase and 42.3% of R plasmids tested were classified to incompatibilty group Inc FI, Inc FII or Inc FIV, 3. Among 48 random selected R plasmids from various origin, 14 R plasmids (including 9 of 14 Inc FII plasmids and 3 of 14 Inc FI plasmids) hybridized with DHFR VII oligonucleotide probe but others did not respond to any of DHFR probes used. 4. Most R plasmids showed various EcoRI endonuclease fragments and different reaction sites by Southern hybridization. Six plasmids showed identical or nearly identical molecular weight, EcoRI endonuclease fragment patterns and different sites of Southern hybridization. But 2 Inc FII plasmids derived from urine and feces showed identical pattern. These findings, if confirmed by further studies, suggest that normal flora E. coli can act as reservoir of resistant genes and, consequently, as a factor in the dissemination of these genes among enteric pathogens and need to be examined further.
Ampicillin ; Chloramphenicol ; Deoxyribonuclease EcoRI ; Drug Resistance, Multiple ; Escherichia coli* ; Escherichia* ; Feces ; Gentamicins ; Immunodeficiency Virus, Feline ; Kanamycin ; Molecular Biology* ; Molecular Weight ; Plasmids ; R Factors ; Tetracycline ; Trimethoprim Resistance* ; Trimethoprim*

INTRODUCTIONAt the time of the study, 3 plasmid-borne qnr determinants (qnrA, qnrB and qnrS) and 1 plasmid-borne aminoglycoside-modifying enzyme determinant that confers quinolone resistance (aac(6')-Ib-cr) had been described in the literature.

MATERIALS AND METHODSWe studied the prevalence of the 3 qnr determinants in a total of 117 nalidixic acid-resistant urinary isolates of Klebsiella pneumoniae (61 isolates) and Escherichia coli (56 isolates) using multiplex polymerase chain reaction (PCR). Further, a subset of the original strains (comprising 14 E. coli and 38 K. pneumoniae) showing reduced susceptibility to the aminoglycosides underwent PCR for aac(6')-Ib, followed by restriction digestion with BtsCI to detect the variant aac(6')-Ib-cr.

RESULTSTwenty-eight of 61 (45.9%) Klebsiella isolates were found to possess at least 1 qnr determinant. Only 1/56 (1.8%) E. coli isolates were found to possess a qnr determinant. Two of the Klebsiella isolates possessed 2 qnr determinants each (qnrB and qnrS). The predominant determinant was qnrB (19 isolates). There were 11 isolates harbouring qnrS, and only 1 with qnrA. 1/14 (7.1%) E. coli and 35/38 K. pneumoniae (92.1%) were found to possess aac(6')-Ib-cr. There was pairwise association between each of qnr, aac(6')-Ib-cr and the presence of an extended-spectrum beta-lactamase.

CONCLUSIONSA high prevalence of plasmid-mediated quinolone resistance determinants [i.e., qnrS, qnrB and aac(6')-Ib-cr] was found in quinolone-resistant K. pneumoniae isolated in a large hospital in Singapore.

Drug Resistance, Bacterial ; Escherichia coli ; drug effects ; isolation & purification ; Hospitals ; Humans ; Klebsiella pneumoniae ; drug effects ; isolation & purification ; Molecular Sequence Data ; Quinolones ; pharmacology ; R Factors ; Singapore ; Urine ; microbiology