Characteristics, epidemiology and clinical importance of emerging strains of Gram-negative bacilli producing extended-spectrum β-lactamases

Shah, Aamer Ali; Hasan, Fariha; Ahmed, Safia; Hameed, Abdul

doi:10.1016/j.resmic.2004.02.009

Cited by 105 publications

(90 citation statements)

References 78 publications

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“…Most K. pneumoniae isolates were obtained from the rectal swab (43.4%; n = 62), which is a part of surveillance culture, followed by urine (18.9%; n = 27) and blood (10.5%; n = 15). The largest number of E. cloacae 43.4% (n = 62) 13.3% (n = 2) 10% (n = 1) was isolated from tracheal secretion (33.3%; n = 5), and urine (26.7%; n = 4) and rectal swabs (13.3%; n = 2) as shown in Table 1.…”

Section: Resultsmentioning

confidence: 99%

“…In a plate there were placed non-supplemented ertapenem, meropenem, and imipenem disks; ertapenem, meropenem and imipenem disks supplemented with AFB; meropenem and imipenem disks supplemented with CLOXA; and meropenem and imipenem disks supplemented with EDTA. The plates were then incubated at 35 ± 2°C for 18 to 24h 13 .…”

Section: Phenotypic Tests With Phenylboronic Acid Cloxacillin and Ementioning

confidence: 99%

“…Isolates with zone difference < 5mm for antimicrobial disks supplemented AFB, CLOXA and EDTA were considered possible producers of another β-lactamase (ex. OXA-48) or porin loss, and the ones that showed a zone difference ≥ 5mm only for disks supplemented with EDTA were considered likely producers of MBL 13 .…”

Section: Phenotypic Tests With Phenylboronic Acid Cloxacillin and Ementioning

confidence: 99%

“…These bacteria are considered important agents of nosocomial infections because they produce carbapenemase, which is an enzyme that hydrolyzes the β-lactam ring of not only carbapenem antibiotics, but also those of cephalosporins, penicillin, and monobactams 13 .…”

Section: Introductionmentioning

confidence: 99%

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Phenotypic methods for screening carbapenem-resistant Enterobacteriaceae and assessment of their antimicrobial susceptibility profile

Silva

Rampelotto

Lorenzoni

et al. 2017

Rev. Soc. Bras. Med. Trop.

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Introduction:In this study, we used phenotypic methods to screen carbapenem-resistant Enterobacteriaceae (CREs) and evaluated their antimicrobial sensitivity profile. Methods: One hundred and seventy-eight CREs were isolated at a university hospital in south Brazil in a one-year period. Samples were assessed using disk diffusion tests with inhibitors of β-lactamases such as phenylboronic acid (AFB), cloxacillin (CLOXA), and ethylenediaminetetraacetic acid (EDTA). Strains with differences in zone diameters ≥ 5mm for disks supplemented or not were considered producers of carbapenemases. Results: Klebsiella pneumoniae was the most prevalent CRE, which appeared in 80.3% cases (n = 143). Among clinical materials, the rectal swab was responsible for 43.4% of the isolations (n = 62), followed by urine (18.9%; n = 27). Among the CREs identified in this study, the growth of 56.7% (n = 101) isolates, which were putative producers of Klebsiella pneumoniae carbapenemase (KPC), were inhibited by AFB, whereas 7.3% (n = 13) isolates were inhibited by both AFB and CLOXA and were considered as putative producers of plasmid-mediated AmpC; approximately 3.4% (n = 6) were inhibited by EDTA, which possibly produced metallo-β-lactamase. Lastly, 32.6% (n = 58) cases showed negative results for AFB, CLOXA, and EDTA sensitivity, and represented another class of β-lactamases and/or mechanism of resistance. Conclusions: Phenotypic screening of CREs is important for clinical laboratories that monitor outbreaks of resistant microbes. Phenotypic tests that use carbapenemase inhibitors and enhancers such as AFB, CLOXA, and EDTA are necessary since they are good screening methods for the detection of carbapenemases.

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Section: Resultsmentioning

confidence: 99%

Section: Phenotypic Tests With Phenylboronic Acid Cloxacillin and Ementioning

confidence: 99%

Section: Phenotypic Tests With Phenylboronic Acid Cloxacillin and Ementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Phenotypic methods for screening carbapenem-resistant Enterobacteriaceae and assessment of their antimicrobial susceptibility profile

Silva

Rampelotto

Lorenzoni

et al. 2017

Rev. Soc. Bras. Med. Trop.

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“…TEM-1 ␤-lactamase is a class A enzyme and is the most common plasmid-encoded ␤-lactamase in Gram-negative bacteria (8). TEM-1 ␤-lactamase efficiently hydrolyzes penicillins and many cephalosporins, but it is not an effective catalyst for extended spectrum cephalosporin turnover (9).…”

mentioning

confidence: 99%

Structural and Biochemical Evidence That a TEM-1 β-Lactamase N170G Active Site Mutant Acts via Substrate-assisted Catalysis

Brown

Shanker

Prasad

et al. 2009

Journal of Biological Chemistry

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TEM-1 ␤-lactamase is the most common plasmid-encoded166 and the hydrolytic water. The goal of this study was to examine the importance of Asn 170 for catalysis and substrate specificity of ␤-lactam antibiotic hydrolysis. The codon for position 170 was randomized to create a library containing all 20 possible amino acids. The random library was introduced into Escherichia coli, and functional clones were selected on agar plates containing ampicillin. DNA sequencing of the functional clones revealed that only asparagine (wild type) and glycine at this position are consistent with wild-type function. The determination of kinetic parameters for several substrates revealed that the N170G mutant is very efficient at hydrolyzing substrates that contain a primary amine in the antibiotic R-group that would be close to the Asn 170 side chain in the acyl-intermediate. In addition, the x-ray structure of the N170G enzyme indicated that the position of an active site water important for deacylation is altered compared with the wildtype enzyme. Taken together, the results suggest the N170G TEM-1 enzyme hydrolyzes ampicillin efficiently because of substrate-assisted catalysis where the primary amine of the ampicillin R-group positions the hydrolytic water and allows for efficient deacylation.

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Liver Transplantation: Prevention and Treatment of Infection

Rimola

Navasa

2010

Evidence‐Based Gastroenterology and Hepatology

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Characteristics, epidemiology and clinical importance of emerging strains of Gram-negative bacilli producing extended-spectrum β-lactamases

Cited by 105 publications

References 78 publications

Phenotypic methods for screening carbapenem-resistant Enterobacteriaceae and assessment of their antimicrobial susceptibility profile

Phenotypic methods for screening carbapenem-resistant Enterobacteriaceae and assessment of their antimicrobial susceptibility profile

Structural and Biochemical Evidence That a TEM-1 β-Lactamase N170G Active Site Mutant Acts via Substrate-assisted Catalysis

Liver Transplantation: Prevention and Treatment of Infection

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