CTX-M-9 group extended-spectrum β-lactamases in neonatal stool isolates: Emergence in India.

The study reports for the first time the identification of CTX-M-14-like and CTX-M-27-like extended-spectrum β-lactamases (ESBLs) belonging to the CTX-M-9 group in Klebsiella pneumoniae and Escherichia coli isolated from the neonatal stool in India. The plasmid carrying the blaCTX-M-9 group in both the isolates was transferable. Till date, no other CTX-M group, except the CTX-M-1 group, has been reported from India. A total of 77% of the neonates had ESBL-producing K. pneumoniae or E. coli in their stool, and blaCTX-M-15 was the predominant ESBL gene. Although the CTX-M-9 group was found in the stool and did not cause infection, the detection of the CTX-M-9 group might be a prelude to future infections.

Clinical Characteristics of Extended-spectrum beta-lactamase Producing Shigella sonnei Infection Outbreaked in Chungju Area / 대한진단검사의학회지

BACKGROUND: An outbreak of extended-spectrum-lactamase (ESBL)-producing Shigella sonnei enteritis, especially in pediatric populations, was unprecedented not only in Korea, but also throughout the world in the past. This study was intended to devise a management guideline for shigellosis caused by an ESBL-producing strain based on analysis of the clinical manifestations and response to therapy. METHODS: We examined 24 strains of S. sonnei isolated from stool cultures of patients with acute enteritis, between November 2004 and February 2005, for antimicrobial susceptibility and ESBL production, and we also performed DNA sequencing with PCR for the typing of ESBL genes. In addition, we retrospectively analyzed the clinical characteristics, laboratory results, and therapeutic responses to antibiotics of the 103 patients who grew S. sonnei on stool cultures. RESULTS: All 24 isolates showed a very similar antibiotic sensitivity pattern and were ESBL gene type of CTX-M-14. The most frequent clinical symptom in the 103 patients was a fever, followed by diarrhea, abdominal pain, headache, vomiting, and nausea. Leukocytosis and CRP were positive in 53.4% and 78.6% of the patients, respectively. On stool direct smears, 11.7% showed more than 50 WBCs per HPF and 71% were positive on stool occult blood. Microbiological eradication rates were as follows: azithromycin and ciprofloxacin, 100%; imipenem-cilastatin, 68.8%; ampicillin-sulbactam, 42.9%; amoxicillin-clavulanic acid, 20%; ceftizoxime, 12.5%; cefdinir, 6.9%; and ceftriaxone and trimethoprim-sulfamethoxazole, 0%. CONCLUSIONS: We presumed that, given its cost-effectiveness and safety, azithromycin can be an attractive option for the treatment of ESBL-producing S. sonnei enteritis in pediatric populations. Although ciprofloxacin is another cost-effective agent, its use in pediatric populations is not recommended.

Emergence and Wide Dissemination of CTX-M-type ESBLs, and CMY-2- and DHA-1-type AmpC beta-Lactamases in Korean Respiratory Isolates of Klebsiella pneumoniae

Respiratory isolates of Klebsiella pneumoniae in Korea during 2002-2003 were studied to determine the prevalence and types of extended-spectrum beta-lactamases (ESBLs) and plasmid-mediated AmpC beta-lactamases (PABLs). ESBL-production was tested by double-disk synergy, and genotypes of beta-lactamases were determined by PCR and sequencing. ESBLs were detected in 28.4% of 373 isolates, and the most prevalent types were SHV-12 (63 isolates) and CTX-M-14 (9 isolates). Forty of 75 ESBL-producers (53.5%) also had PABLs: 21 isolates with CMY-2-like, 17 with DHA-1-like. Pulsed-field gel electrophoresis showed 19 types and 25 of 74 isolates had an identical pattern, indicating nosocomial spread. Dissemination of ESBL- and PABL-producing K. pneumoniae strains in Korea is a particular concern, as it limits the choice of antimicrobial agents for treatment of infections.

Dissemination of CTX-M Type Extended-Spectrum beta-Lactamases and Emergence of CTX-M-12 in Escherichia coli / 대한진단검사의학회지

BACKGROUND: Clinical isolates of Escherichia coli were evaluated to determine the prevalence and genotypes of Ambler class A extended-spectrum beta -lactamases (ESBLs). METHODS: Clinical isolates of E. coli were collected from 12 hospitals from February through July, 2004. Antimicrobial susceptibility was tested by disk diffusion and agar dilution methods, and ESBLproduction was determined by double-disk synergy test. TEM, SHV, CTX-M, PER-1, VEB, IBC, GES, and TLA type ESBL genes were detected by PCR amplifications, and the PCR products were subjected to direct sequencing. RESULTS: The double-disk synergy test was positive in 90.9% (149 in 164) of the ceftazidime- or cefotaxime-resistant E. coli isolates. The most prevalent types of Ambler class A ESBLs in E. coliisolates were CTX-M-15 (n=53). CTX-M-14 (n=24), CTX-M-3 (n=9), CTX-M-9 (n=3), CTX-M-12 (n=3), SHV-2a (n=1), SHV-12 (n=5) and TEM-52 (n=3) were also found. CTX-M-12 ESBL had never been reported before in Korea. CONCLUSIONS: CTX-M type ESBL-producing E. coli isolates are spreading and CTX-M-12 is emerging in Korea.

Prevalence of CTX-M-type Extended-Spectrum beta-Lactamase-Producing Esherichia coli and Klebsiella pneumoniae Isolates in Korea / 대한임상미생물학회지

BACKGROUND: The aim of this study was to survey the nation wide susceptibilities of Esherichia coli and Klebsiella pneumoniae against cefotaxime and to determine the prevalence of CTX-M-type extended-spectrum beta- lactamases(ESBLs). METHODS: During the period of April to June, 2002, E. coli and K. pneumoniae isolates were collected from 13 hospitals. Antimicrobial susceptibilities to cefotaxime were tested by the disk diffusion method. ESBL production was determined by double disk synergy test. Cefotaxime-resistance of the ESBL-producers was transferred to azide-resistant E. coli J53 by conjugation. MICs of beta- lactam antibiotics were determined by agar dilution method. Searches for blaCTX-M genes were performed by PCR amplication. pIs of beta-lactamases were determined by isoelectric focusing. RESULTS: Ten percents of E. coli and 35 percents of K. pneumoniae isolates among 260 strains of each were intermediate or resistant to cefotaxime. Twenty-three isolates of E. coli and 78 K. pneumoniae isolates showed positive results in the double disk synergy test. One isolate of E. coli and 2 K. pneumoniae isolates harbored blaCTX-M-3 gene, 2 E. coli isolates harbored blaCTX-M-15 gene, and 2 E. coli and 2 K. pneumoniae isolates harbored blaCTX-M-14 gene. CONCLUSION: E. coli and K. pneumoniae isolates producing CTX-M-type ESBLs are not uncommon in Korean hospitals. The spread of CTX-M-type ESBL genes could compromise the future usefulness of 3rd generation cephalosporins and aztreonam for the treatment of E. coli and K. pneumoniae infections.

Prevalence of CTX-M-type Extended-Spectrum beta-Lactamase-Producing Escherichia coli and Klebsiella pneumoniae Isolates in Korea, 2003 / 대한임상미생물학회지

BACKGROUND: The aims of this study were to survey nationwide susceptibilities of Escherichia coli and Klebsiella pneumoniae isolates against cefotaxime and to determine the prevalences of CTX-Mtype extended-spectrum beta-lactamases(ESBLs). METHODS: During the period of February to July, 2003, E. coli and K. pneumoniae isolates were collected from 12 hospitals. Antimicrobial susceptibilities to cefotaxime were tested by the disk diffusion method. ESBL production was determined by the double disk synergy test. Cefotaxime-resistance of the ESBL-producers was transfered to E. coli DH5alphaand E. coli Top10-F by transformation. MICs of beta-lactam antibiotics were determined by the agar dilution method. Searches for blaCTX-M genes was performed by PCR amplication; pIs of beta-lactamases were determined by isoelectric focusing. RESULTS: Among 230 isolates of E. coli and 232 isolates of K. pneumoniae, 27 (11.7%) and 79 (34.1%) were intermediate or resistant to cefotaxime, respectively. Twenty-four (10.4%) isolates of E. coli and 58 (25.0%) K. pneumoniae isolates showed positive results in the double disk synergy test. Three isolates of E. coli and 13 K. pneumoniae isolates harbored blaCTX-M-3 gene, 4 E. coli isolates harbored blaCTX-M-15 gene, and 1 E. coli and 5 K. pneumoniae isolates harbored blaCTX-M-14 gene. CONCLUSION: E. coli and K. pneumoniae isolates producing CTX-M-type ESBLs were not uncommon in Korean hospitals. It is thought that periodical surveys are necessary for inspecting the spread of CTX-M-type ESBL genes are necessary.

Prevalence of CTX-M Extended-spectrum Beta-lactamases in Clinical Isolates of Enterobacteriaceae in Korea

The evolution and dissemination of extended-spectrum beta-lactamases (ESBL) have compromised the clinical use of third-generation cephalosporins worldwide. Although most ESBLs belong to the TEM and SHV beta-lactamase families, the members of CTX-M, a novel ESBL family, are increasing worldwide in Gram-negative bacteria. We examined the prevalence of CTX-M ESBL in clinical isolates of the family Enterobacteriaceae collected from three university hospitals located in three different cities in Korea. Among a total of 603 isolates collected, 163 isolates (27.0%) revealed > or =2 microgram/ ml of MIC against cefotaxime, and 93 isolates (15.4%) produced ESBL confirmed by the double disk synergy test. Among 93 ESBL-producing isolates, blaCTX-M genes were detected in 41 isolates by PCR method and they included 1 isolate of C. freundii, 3 of E. aerogenes, 2 of E. cloacae, 17 of E. coli, 9 of K. pneumoniae, and 9 of S. marcescens. Thus, the overall prevalence of CTX-M ESBL-producing isolates among the family Enterobacteriaceae was 6.8% (41 of 603 isolates) and the proportion of CTX-M-producers among the ESBL-producing isolates was 44.1% (41 of 93 isolates). Further determination of the blaCTX-M subtype by nucleotide sequencing revealed blaCTX-M-3 in 17, blaCTX-M-15 in 11, blaCTX-M-14 in 9, and blaCTX-M-9 in 4 isolates. To our knowledge, this is the first report on the dissemination of CTX-M ESBL among clinical isolates of the family Enterobacteriaceae in Korea.

Prevalence of CTX-M Extended-spectrum Beta-lactamases in Clinical Isolates of Enterobacteriaceae in Korea

The evolution and dissemination of extended-spectrum beta-lactamases (ESBL) have compromised the clinical use of third-generation cephalosporins worldwide. Although most ESBLs belong to the TEM and SHV beta-lactamase families, the members of CTX-M, a novel ESBL family, are increasing worldwide in Gram-negative bacteria. We examined the prevalence of CTX-M ESBL in clinical isolates of the family Enterobacteriaceae collected from three university hospitals located in three different cities in Korea. Among a total of 603 isolates collected, 163 isolates (27.0%) revealed > or =2 microgram/ ml of MIC against cefotaxime, and 93 isolates (15.4%) produced ESBL confirmed by the double disk synergy test. Among 93 ESBL-producing isolates, blaCTX-M genes were detected in 41 isolates by PCR method and they included 1 isolate of C. freundii, 3 of E. aerogenes, 2 of E. cloacae, 17 of E. coli, 9 of K. pneumoniae, and 9 of S. marcescens. Thus, the overall prevalence of CTX-M ESBL-producing isolates among the family Enterobacteriaceae was 6.8% (41 of 603 isolates) and the proportion of CTX-M-producers among the ESBL-producing isolates was 44.1% (41 of 93 isolates). Further determination of the blaCTX-M subtype by nucleotide sequencing revealed blaCTX-M-3 in 17, blaCTX-M-15 in 11, blaCTX-M-14 in 9, and blaCTX-M-9 in 4 isolates. To our knowledge, this is the first report on the dissemination of CTX-M ESBL among clinical isolates of the family Enterobacteriaceae in Korea.

Drug Resistance Genes of Eight CTX-M-14 Variant Genotypes from Klebsiella pneumoniae and Escherichia coli / 中华医院感染学杂志

OBJECTIVE To analyze the sequences of drug resistance genes of the novel CTX-M type of extended spectrum ?-lactamases((ESBLs)) in Hefei Anhui Province. METHODS A pair of primers were designed to detect the groups of CTX-M-9 by PCR from 98 strains confirmed(ESBLs)-producing Klebsiella pneumoniae and Escherichia coli isolated between 1999 and 2000 in Hefei,and then sequenced the productions of PCR,Compared the sequences on blast via GenBank and analyzed the molecular structure to find out whether the change in nucleotides had induced the destitution of amino acid in specific site. RESULTS Of 29 strains,8 variant sequences of CTX-M-14 had been discovered in several sites and resulted in the destitution of amino acid. CONCLUSIONS There are novel CTX-M types of(ESBLs) in Hefei,which come from CTX-M-14.