scholarly journals A Novel Extended-Spectrum TEM-Type β-Lactamase (TEM-52) Associated with Decreased Susceptibility to Moxalactam inKlebsiella pneumoniae

1998 ◽  
Vol 42 (1) ◽  
pp. 108-113 ◽  
Author(s):  
Claire Poyart ◽  
Pierre Mugnier ◽  
Gilles Quesne ◽  
Patrick Berche ◽  
Patrick Trieu-Cuot
Keyword(s):  
Sequence Analysis ◽  
Amino Acid Substitutions ◽  
Diffusion Test ◽  
Disk Diffusion Test ◽  
Mobilizable Plasmid ◽  
Allelic Replacement ◽  
Extended Spectrum ◽  
Amoxicillin Clavulanate ◽  
Previously Treated ◽  
Element Sequence

ABSTRACT Klebsiella pneumoniae NEM865 was isolated from the culture of a stool sample from a patient previously treated with ceftazidime (CAZ). Analysis of this strain by the disk diffusion test revealed synergies between amoxicillin-clavulanate (AMX-CA) and CAZ, AMX-CA and cefotaxime (CTX), AMX-CA and aztreonam (ATM), and more surprisingly, AMX-CA and moxalactam (MOX). Clavulanic acid (CA) decreased the MICs of CAZ, CTX, and MOX, which suggested that NEM865 produced a novel extended-spectrum β-lactamase. Genetic, restriction endonuclease, and Southern blot analyses revealed that the resistance phenotype was due to the presence in NEM865 of a 13.5-kb mobilizable plasmid, designated pNEC865, harboring a Tn3-like element. Sequence analysis revealed that the blaT gene of pNEC865 differed from bla TEM-1 by three mutations leading to the following amino acid substitutions: Glu104→Lys, Met182→Thr, and Gly238→Ser (Ambler numbering). The association of these three mutations has thus far never been described, and theblaT gene carried by pNEC865 was therefore designatedbla TEM-52. The enzymatic parameters of TEM-52 and TEM-3 were found to be very similar except for those for MOX, for which the affinity of TEM-52 (Ki , 0.16 μM) was 10-fold higher than that of TEM-3 (Ki , 1.9 μM). Allelic replacement analysis revealed that the combination of Lys104, Thr182, and Ser238 was responsible for the increase in the MICs of MOX for the TEM-52 producers.

scholarly journals Infections with Nontyphoidal Salmonella Species Producing TEM-63 or a Novel TEM Enzyme, TEM-131, in South Africa

2004 ◽  
Vol 48 (11) ◽  
pp. 4263-4270 ◽  
Author(s):  
Tersia Kruger ◽  
Dora Szabo ◽  
Karen H. Keddy ◽  
Kathleen Deeley ◽  
Jane W. Marsh ◽  
...  
Keyword(s):  
South Africa ◽  
Public Health Problem ◽  
Amino Acid Substitutions ◽  
Diffusion Test ◽  
Disk Diffusion Test ◽  
Beta Lactamases ◽  
Extended Spectrum ◽  
Significant Public Health Problem ◽  
Significant Public Health ◽  
Extended Spectrum Beta Lactamases

ABSTRACT Salmonella spp. producing extended-spectrum beta-lactamases (ESBLs) have been reported in many countries, but there is no information on their prevalence in Africa. ESBL-producing Salmonella enterica serotype Isangi and S. enterica serotype Typhimurium strains have been noted in South Africa since 2001. A total of 160 consecutive isolates of Salmonella spp. were collected from 13 hospitals located in different cities in South Africa over a 5-month period from December 2002 to April 2003. All strains were screened for production of ESBLs by the double disk diffusion test and for AmpC production by assessing resistance to cefoxitin. bla SHV, bla TEM, bla CTX-M, and bla CMY-2 were sought from all ESBL-positive and cefoxitin-resistant isolates. A total of 15.6% (25 of 160) isolates produced SHV or TEM ESBLs, and 1.9% (3 of 160) produced CMY-2. Nine S. enterica serotype Typhimurium, eight S. enterica serotype Isangi, and three S. enterica serotype Muenchen strains produced either TEM-63 or a derivative of TEM-63 designated TEM-131. Both TEM-63 and TEM-131 have an isoelectric point of 5.6, and their sequences have the following amino acid substitutions compared to the TEM-1 sequence: Leu21Phe, Glu104Lys, Arg164Ser, and Met182Thr. Additionally, TEM-131 has an Ala237Thr substitution. ESBL-producing Salmonella spp. have become a significant public health problem in South Africa with particular implications for the treatment of serious nontyphoidal Salmonella infections in children, for whom extended-spectrum cephalosporins were the preferred treatment.

scholarly journals Detection of Extended-Spectrum β-Lactamases in Clinical Isolates of Pseudomonas aeruginosa

2006 ◽  
Vol 50 (9) ◽  
pp. 2990-2995 ◽  
Author(s):  
Xiaofei Jiang ◽  
Zhe Zhang ◽  
Min Li ◽  
Danqiu Zhou ◽  
Feiyi Ruan ◽  
...  
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Multidrug Resistant ◽  
Clinical Isolates ◽  
Screening Methods ◽  
Extended Spectrum ◽  
Pcr Product ◽  
Amoxicillin Clavulanate ◽  
Synergy Test ◽  
Esbl Producers ◽  
Disk Test

ABSTRACT With the occurrence of extended-spectrum β-lactamases (ESBLs) in Pseudomonas aeruginosa being increasingly reported worldwide, there is a need for a reliable test to detect ESBLs in clinical isolates of P. aeruginosa. In our study, a total of 75 clinical isolates of P. aeruginosa were studied. Nitrocefin tests were performed to detect the β-lactamase enzyme; isoelectric focusing electrophoresis, PCR, and PCR product sequencing were designed to further characterize the contained ESBLs. Various ESBL-screening methods were designed to compare the reliabilities of detecting ESBLs in clinical isolates of P. aeruginosa whose β-lactamases were well characterized. Thirty-four of 36 multidrug-resistant P. aeruginosa clinical isolates were positive for ESBLs. bla VEB-3 was the most prevalent ESBL gene in P. aeruginosa in our study. Among the total of 34 isolates that were considered ESBL producers, 20 strains were positive using conventional combined disk tests and 10 strains were positive using a conventional double-disk synergy test (DDST) with amoxicillin-clavulanate, expanded-spectrum cephalosporins, aztreonam, and cefepime. Modifications of the combined disk test and DDST, which consisted of shorter distances between disks (20 mm instead of 30 mm) and the use of three different plates that contained cloxacillin (200 μg/ml) alone, Phe-Arg β-naphthylamide dihydrochloride (MC-207,110; 20 μg/ml) alone, and both cloxacillin (200 μg/ml) and MC-207,110 (20 μg/ml) increased the sensitivity of the tests to 78.8%, 91.18%, 85.29%, and 97.06%.

Characterization of Extended-Spectrum β-Lactamase–Producing Escherichia coli Strains Isolated from Retail Foods in Shaanxi Province, China

2015 ◽  
Vol 78 (5) ◽  
pp. 1018-1023 ◽  
Author(s):  
MEILI XI ◽  
QIAN WU ◽  
XIN WANG ◽  
BAOWEI YANG ◽  
XIAODONG XIA ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Shaanxi Province ◽  
People’S Republic Of China ◽  
People's Republic Of China ◽  
M Gene ◽  
Disk Diffusion Test ◽  
Republic Of China ◽  
E Coli ◽  
Extended Spectrum

Extended-spectrum β-lactamase (ESBL)–producing Escherichia coli strains have been reported worldwide; however, the incidence and characterization of foodborne ESBL-producing E. coli strains have been rarely reported in the People's Republic of China. Among a collection of 659 E. coli isolates recovered from retail foods in Shaanxi Province, People's Republic of China, 223 cefoxitin-resistant and/or cefoperazone-resistant isolates were screened for ESBL production with the double disk diffusion test. The ESBL-producing isolates were characterized for antimicrobial resistance and the presence of blaTEM, blaSHV, and blaCTX-M genes. Isolates with blaCTX-M were further classified by PCR as having blaCTX-M-1, blaCTX-M-2, blaCTX-M-8, blaCTX-M-9, or blaCTX-M-25. One hundred forty-seven isolates were identified as ESBL positive. PCR detection revealed that 146 isolates (99.3%) contained the blaCTX-M gene. Among these isolates, 42 (28.8%) were positive for the enzyme CTX-M-1, 5 (3.4%) for CTX-M-2, and 99 (67.8%) for CTX-M-9. No CTX-M-8 and CTX-M-25 were found in this study. One hundred fifteen isolates (78.2%) were positive for the blaTEM gene, but blaSHV was not detected. Among the 147 ESBL-producing E. coli isolates, 75 (51.0%), 35 (23.8%), and 4 (2.7%) isolates were positive for blaTEM and blaCTX-M-9, blaTEM and blaCTX-M-1, and blaTEM and blaCTX-M-2, respectively. All of the 147 ESBL-producing isolates were resistant to three or more non–β-lactam antibiotics. This study provides evidence that foodborne E. coli can harbor ESBL-encoding genes. Thus, food could be a vehicle for the dissemination of ESBL-producing E. coli strains, a situation that requires surveillance and appropriate management strategies.

scholarly journals Evaluation of Mannitol Salt Agar for Detection of Oxacillin Resistance in Staphylococcus aureus by Disk Diffusion and Agar Screening

1998 ◽  
Vol 36 (8) ◽  
pp. 2254-2257 ◽  
Author(s):  
Günter Kampf ◽  
Christoph Lecke ◽  
Ann-Katrin Cimbal ◽  
Klaus Weist ◽  
Henning Rüden
Keyword(s):  
Staphylococcus Aureus ◽  
Disk Diffusion ◽  
Diffusion Test ◽  
Mannitol Salt Agar ◽  
Disk Diffusion Test ◽  
Zone Diameter ◽  
Oxacillin Resistance

Mannitol salt agar was evaluated for detection of oxacillin resistance in 136 Staphylococcus aureus isolates. AllmecA-positive isolates (n = 54) were correctly categorized as oxacillin resistant by the disk diffusion test (1-μg disk; zone diameter, <16 mm); the specificity was 97.6%. Agar screening (2 μg of oxacillin per ml) revealed a sensitivity of 98.1% and a specificity of 95.1%.

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