Comparison of a novel, inhibitor-potentiated disc-diffusion test with other methods for the detection of extended-spectrum beta-lactamases in Escherichia coli and Klebsiella pneumoniae

Ho, Pak‐Leung; Chow, Kin-Hung; Yuen, Kwok‐Yung; Ng, W. S.; Chau, Pui Hing

doi:10.1093/jac/42.1.49

Cited by 59 publications

(41 citation statements)

References 15 publications

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“…In a review of studies which have evaluated collections of ESBL-producing organisms using standard CLSI disk diffusion or MIC breakpoints, 13 to 49% of isolates were cefotaxime susceptible, 36 to 79% ceftriaxone susceptible, 11 to 52% ceftazidime susceptible, and 10 to 67% aztreonam susceptible. Approximately 40% tested susceptible to at least one oxyimino ␤-lactam and 20% to all oxyimino ␤-lactams (91,94,165,179,289,393,409). The reasons for this apparent susceptibility to some cephalosporins is the result of various degrees of hydrolysis of cephalosporins by different ␤-lactamases and enhanced penetration through the bacterial outer membrane of some cephalosporins compared to others.…”

Section: Need For Clinical Microbiology Laboratories To Detect Esbl Pmentioning

confidence: 99%

Extended-Spectrum β-Lactamases: a Clinical Update

2005

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SUMMARY Extended-spectrum β-lactamases (ESBLs) are a rapidly evolving group of β-lactamases which share the ability to hydrolyze third-generation cephalosporins and aztreonam yet are inhibited by clavulanic acid. Typically, they derive from genes for TEM-1, TEM-2, or SHV-1 by mutations that alter the amino acid configuration around the active site of these β-lactamases. This extends the spectrum of β-lactam antibiotics susceptible to hydrolysis by these enzymes. An increasing number of ESBLs not of TEM or SHV lineage have recently been described. The presence of ESBLs carries tremendous clinical significance. The ESBLs are frequently plasmid encoded. Plasmids responsible for ESBL production frequently carry genes encoding resistance to other drug classes (for example, aminoglycosides). Therefore, antibiotic options in the treatment of ESBL-producing organisms are extremely limited. Carbapenems are the treatment of choice for serious infections due to ESBL-producing organisms, yet carbapenem-resistant isolates have recently been reported. ESBL-producing organisms may appear susceptible to some extended-spectrum cephalosporins. However, treatment with such antibiotics has been associated with high failure rates. There is substantial debate as to the optimal method to prevent this occurrence. It has been proposed that cephalosporin breakpoints for the Enterobacteriaceae should be altered so that the need for ESBL detection would be obviated. At present, however, organizations such as the Clinical and Laboratory Standards Institute (formerly the National Committee for Clinical Laboratory Standards) provide guidelines for the detection of ESBLs in klebsiellae and Escherichia coli. In common to all ESBL detection methods is the general principle that the activity of extended-spectrum cephalosporins against ESBL-producing organisms will be enhanced by the presence of clavulanic acid. ESBLs represent an impressive example of the ability of gram-negative bacteria to develop new antibiotic resistance mechanisms in the face of the introduction of new antimicrobial agents.

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Section: Need For Clinical Microbiology Laboratories To Detect Esbl Pmentioning

confidence: 99%

Extended-Spectrum β-Lactamases: a Clinical Update

2005

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“…The antibacterial activities of C. edulis extract were determined using the antibiotic disc diffusion assay ("Kirby-Bauer" assay) [10]. Briefly, bacterial strains (E. coli, B. diminuta, B. magaterium and M. luteus) were grown at 37°C in Luria-Bertani broth and their optical density adjusted to 1.0 at 595 nm.…”

Section: Antibacterial Testmentioning

confidence: 99%

“…The crude metanolic extract of C. edulis were tested against bacteria and yeast using the disc diffusion assay [10]. The results revealed that C. edulis extract inhibited growth of B. diminuta, M. luteus and B. magaterium.…”

Section: Edulis Extracts Exhibited Antibacterial But No Antifungalmentioning

confidence: 99%

Antibacterial and Anti-Acanthamoebic Properties of Catha Edulis (Khat)

Siddiqui¹

2012

J Bacteriol Parasitol

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Infectious diseases remain a significant threat to human health, contributing to more than 17 million annual deaths thus indicating an urgent need to identify novel molecules for antimicrobial chemotherapy. Here, the antimicrobial activities of aqueous crude extract of Catha edulis (khat widely used in Africa and southern parts of Arabia) were tested against a panel of microorganisms including Gram-positive bacteria (Bacillus magaterium, Micrococcus luteus), Gram-negative bacteria (Escherichia coli, Brevundimonas diminuta), yeast (Aspergillus varicoluor, Penicillum solitum, Penicillum brevicompactum) and the protist (Acanthamoeba castellanii) in vitro. At 100 µg, C. edulis extracts exhibited potent antibacterial activity against B. diminuta (19 mm ± 2.3), B. magaterium (16 mm ± 0.7) and M. luteus (22 mm ± 3.1) but not against E. coli and yeast (A. varicoluor, P. solitum, P. brevicompactum). Notably, C. edulis extracts showed amoebicidal effects (>50 % reduction in amoeba numbers of the original inoculum) as evidenced by the uptake of Trypan blue dye. The remaining sub-population of A. castellanii remained viable but cultures remained static over longer incubations. These findings show that C. edulis extract possess selective antibacterial properties. For the first time, it is shown that C. edulis extract exhibit anti-Acanthamoebic properties. Further studies are needed to identify active components and assess their clinical relevance.Antibacterial and Anti-Acanthamoebic Properties of Catha Edulis (Khat) leaves of Catha edulis were purchased from a Somali shop on Edgware Road, London, UK. Approximately, 55 g of the plant material were ground and soaked in 100 mL of methanol (100 %) in a water bath at 25°C for 24 h with continuous shaking using Cole Parmer Orbital shaker at 40 g. The extract was filtered, concentrated at 40°C under reduced pressure, and methanol was dried in a freeze-dryer [8]. Finally, the extracts were re-suspended in 20 mL methanol and stored at 4°C until tested for antimicrobial activities. High performance liquid chromatography (HPLC)The crude methanolic extract were applied to a reverse phase C18 column with flow rate of 1 mL per min. Using HPLC, methanolic extracts were eluted with 0, 50 and 100 % methanol. Fraction collected from the crude methanolic extract were freeze dried. The lyophilised fractions were reconstituted in 1 mL of methanol and tested for antimicrobial activities [9]. Microbial strainsThe microbial strains used in the present study were bacteria [Escherichia coli K1 strain RS218 (O18:K1:H7), a cerebrospinal fluid isolate from a neonate with meningitis, and environmental isolates of Brevundimonas diminuta, Bacillus magaterium, Micrococcus luteus], yeast (Aspergillus varicolor, Penicillium solitum, P. brevicompactum), and the protist (Acanthamoeba castellanii, a keratitis isolate belonging to the T4 genotype). All isolates were available in the University microbial collection (stored at -80°C and available upon request)

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“…Unfortunately, many Enterobacteriaceae producing these new ␤-lactamases do not show frank resistance in routine susceptibility tests with certain ␤-lactam antibiotics despite clinical evidence that the drugs do not provide effective therapy (8,10,21,29,44). Thus, it has become imperative to design tests that will help microbiologists identify which ␤-lactamase(s) may be present in a clinical isolate of Enterobacteriaceae (8,11,12,17,20,25,33,34,(38)(39)(40).A series of studies have been performed to determine whether or not results of microdilution panels with or without ␤-lactamase inhibitors could be used to determine the presence of certain ␤-lactamases among species within the family Enterobacteriaceae (13,25,41). Results have shown that a broad variety of ␤-lactam drugs would be required for a ␤-lactamase identification panel and that accurate identification would require complex logic pathways involving multiple drugs.…”

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confidence: 99%

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βlasEN: Microdilution Panel for Identifying β-Lactamases Present in Isolates of Enterobacteriaceae

et al. 2002

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A dried investigational use-only microdilution panel named ␤lasEN (a short named derived from the panel's purpose, to identify ␤-lactamases in Enterobacteriaceae) containing 10 ␤-lactam drugs with and without ␤-lactamase inhibitors was developed to identify ␤-lactamases among clinical isolates of Escherichia coli, Klebsiella pneumoniae, Klebsiella oxytoca, Citrobacter koseri, Citrobacter freundii group, Enterobacter spp., and Serratia marcescens. The MICs obtained with a collection of 383 organisms containing well-characterized ␤-lactamases were used to develop numeric codes and logic pathways for computerized analysis of results. The resultant logic pathways and ␤lasEN panel were then used to test and identify ␤-lactamases among 885 isolates of Enterobacteriaceae recovered in cultures obtained at six different hospital laboratories across the United States. ␤-Lactamases present in 801 (90.5%) of the 885 isolates were identified by ␤lasEN by using the existing logic pathways and codes or after minor modifications were made to the existing codes. The 84 strains that gave codes that ␤lasEN could not identify were collected, reidentified, and retested by using ␤lasEN. Three strains had been misidentified, 54 strains gave different codes upon repeat testing that could be identified by ␤lasEN, and 27 strains repeated new codes. The ␤-lactamases in these strains were identified, and the new codes were added to the ␤lasEN logic pathways. These results indicate that ␤lasEN can identify clinically important ␤-lactamases among most isolates of Enterobacteriaceae. The results also show that good quality control and attention to proper performance of the tests are essential to the correct performance of ␤lasEN.Over the past 10 years, there has been a significant increase in the numbers and types of ␤-lactamases encountered among clinical isolates of Enterobacteriaceae (4-7, 9, 14-16, 18, 23, 31, 37; H. Kurokawa et al., Letter, Lancet 354:955, 1999). Not only have the older plasmid-mediated ␤-lactamases such as TEM-1 and SHV-1 become more prevalent but also new derivatives of these enzymes capable of producing resistance to expandedspectrum ␤-lactam antibiotics have appeared (9,19). Plasmid derivatives of chromosomal ␤-lactamases have also appeared (2, 9, 14), as have enzymes capable of producing resistance to the carbapenems (9, 12, 22, 28; G. Cornaglia et al., Letter, Lancet 353:899-900, 1999). Unfortunately, many Enterobacteriaceae producing these new ␤-lactamases do not show frank resistance in routine susceptibility tests with certain ␤-lactam antibiotics despite clinical evidence that the drugs do not provide effective therapy (8,10,21,29,44). Thus, it has become imperative to design tests that will help microbiologists identify which ␤-lactamase(s) may be present in a clinical isolate of Enterobacteriaceae (8,11,12,17,20,25,33,34,(38)(39)(40).A series of studies have been performed to determine whether or not results of microdilution panels with or without ␤-lactamase inhibitors could be used to determine the presen...

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Comparison of a novel, inhibitor-potentiated disc-diffusion test with other methods for the detection of extended-spectrum beta-lactamases in Escherichia coli and Klebsiella pneumoniae

Cited by 59 publications

References 15 publications

Extended-Spectrum β-Lactamases: a Clinical Update

Extended-Spectrum β-Lactamases: a Clinical Update

Antibacterial and Anti-Acanthamoebic Properties of Catha Edulis (Khat)

βlasEN: Microdilution Panel for Identifying β-Lactamases Present in Isolates of Enterobacteriaceae

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