Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0276640 (TEM)
 20,729 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We surveyed 161 clinical isolates of ampicillin-resistant, beta-lactamase-producing isolates of Haemophilus influenzae obtained between 1975 and 1985 to determine whether they produced TEM-1 or Rob beta-lactamase. Plasmid DNA was obtained from a Rob-producing isolate, F990, and a plasmid (pBR322) known to encode TEM-1. Both plasmids were labeled with 32P and hybridized to whole cell DNA obtained from the clinical isolates. All 161 isolates hybridized with one of the plasmid probes and could be classified as TEM-1- or Rob-producing isolates. Analysis of the distinctive pH profiles of the two beta-lactamases was used to confirm the findings of the DNA hybridization assay. Overall, 13 (8%) isolates obtained from patients in California, North Carolina, Tennessee, Missouri, Louisiana, and Mississippi produced the Rob beta-lactamase. The remaining isolates elaborated the TEM-1 enzyme. We conclude that ampicillin resistance in H. influenzae may be mediated by the production of Rob beta-lactamase and that the occurrence of this enzyme is not limited to the two isolates described to date.
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PMID:Epidemiology of rob beta-lactamase among ampicillin-resistant Haemophilus influenzae isolates in the United States. 325 84

The most common cause of ampicillin resistance in Haemophilus influenzae type b is production of TEM-1 beta-lactamase; however, a novel enzyme with a similar substrate profile but a quite different isoelectric point has also been described. This beta-lactamase, designated ROB-1, has not been found previously in any other organism. In a survey of 46 ampicillin-resistant H. influenzae type b isolates, we found a second human isolate that produces ROB-1 and discovered that ampicillin-resistant isolates of the porcine pathogen Haemophilus pleuropneumoniae also produced ROB-1. In both Haemophilus species ROB-1 production was determined by plasmids that had considerable DNA sequence homology. However, the ROB-1 and TEM-1 beta-lactamase genes were not related. Our findings suggest that this form of ampicillin resistance has an animal reservoir and that conditions fostering its prevalence in animal strains may play a role in the spread of resistance to human pathogens.
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PMID:An animal source for the ROB-1 beta-lactamase of Haemophilus influenzae type b. 348 84

Available data indicate that the most common beta-lactamase produced by Branhamella catarrhalis is plasmid mediated. The same enzyme occurs in Moraxella nonliquefaciens, a commensal in the upper respiratory tract. The ability to produce the enzyme, which is known as BRO-1, can be transferred by conjugation from M. nonliquefaciens to B. catarrhalis. Since the first beta-lactamase-producing strains of B. catarrhalis appeared in 1977, the frequency of beta-lactamase production has increased rapidly; figures as high as 76% have been reported. The plasmid-mediated beta-lactamase TEM-1 occurs in several species of the genus Haemophilus. While the frequency of beta-lactamase production in H. influenzae is reported to be 10-15%, the incidence is significantly higher in non-pathogenic Haemophilus species. Both phenoxymethyl-penicillin and ampicillin promote the occurrence of beta-lactamase-producing strains, but the selective pressure exerted by ampicillin seems to be more pronounced. It may be possible to reduce the ecological effects of the penicillins by avoiding overdiagnosis of the most common bacterial infections of the respiratory tract, and by shortening the courses of antibiotic treatment.
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PMID:Upper respiratory tract infections. Ecological and therapeutic aspects of beta-lactamase production with special reference to Branhamella catarrhalis. 348 90

A total of 114 strains of Haemophilus influenza were characterized with respect to beta-lactamase production and ampicillin MIC. Of this total, 41 strains produced a TEM-type beta-lactamase, and ampicillin MICs for these strains were greater than or equal to 2.0 microgram/ml. It was found that 54 strains lacked TEM-type beta-lactamase activity, and ampicillin MICs for them were less than or equal to 0.5 microgram/ml. The remaining 19 strains were beta-lactamase negative, but ampicillin MICs were greater than or equal to 2.0 micrograms/ml. Disk diffusion susceptibility tests were performed with two media, i.e., Mueller-Hinton agar containing 1.0% hemoglobin and 1.0% IsoVitaleX supplement (CHOC-MHA) and enriched chocolate agar (CHOC), by using disks containing 10 and 2 micrograms of ampicillin. If strains of H. influenzae for which ampicillin MICs were greater than or equal to 2.0 micrograms/ml were considered resistant, while strains for which MICs were less than or equal to 0.5 microgram/ml were considered susceptible, the following zone diameter interpretive criteria were identified as indicating ampicillin susceptibility: CHOC-MHA (10-micrograms disks), greater than or equal to 20 mm; CHOC-MHA (2-micrograms disks), greater than or equal to 17 mm; CHOC (10-micrograms disks), greater than or equal to 25 mm; and CHOC (2-micrograms disks), greater than or equal to 20 mm. In all cases, zones of inhibition less than those listed above would be interpreted as indicating resistance. Each of these four combinations was found to be essentially equivalent in identifying susceptible and resistant strains of H. influenzae, irrespective of beta-lactamase production.
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PMID:Ampicillin disk diffusion susceptibility testing of Haemophilus influenzae. 349 38

The incidence and mechanisms of ampicillin resistance (MIC greater than 1 mg/l) were investigated in 105 clinical isolates of Haemophilus influenzae collected in Edinburgh during 1983/4. Fifteen (14.3%) ampicillin-resistant strains were identified and these were non-serotypable and comprised six biotypes. Isoelectric focusing and beta-lactamase-inhibition studies demonstrated that production of the TEM-1 beta-lactamase was the principal mechanism of resistance in nine (60%) strains. Radiolabelling revealed that one beta-lactamase-positive strain also had an unusual penicillin-binding protein (PBP) profit. No beta-lactamase activity was detected in the other six (40%) ampicillin-resistant strains. Two beta-lactamase-negative ampicillin-resistant strains had atypical PBP profiles. SDS-PAGE analysis showed that four beta-lactamase-negative ampicillin-resistant strains, including one with altered PBPs, exhibited outer membrane protein profiles which differed from those of sensitive strains of the same biotype. The ampicillin-resistance mechanism of the remaining strain could not be determined. Thus, several resistance mechanisms, either acting individually or in combination, are implicated in ampicillin resistance in H. influenzae.
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PMID:Ampicillin resistance in Haemophilus influenzae: identification of resistance mechanisms. 350 21

Documented ampicillin treatment failures of systemic Haemophilus influenzae type b infections have been associated with synthesis of a TEM-1 beta-lactamase. A patient with H. influenzae type b meningitis in whom ampicillin treatment failed is described; the isolate was beta-lactamase-negative according to the cell suspension chromogenic cephalosporin assay. The false-negative result occurred in a strain which elaborated a novel, plasmid-mediated beta-lactamase with characteristics which distinguish it from TEM-1 beta-lactamase. Clinically important ampicillin resistance in H. influenzae type b occurs by mechanisms other than by synthesis of TEM-1 beta-lactamase. Diagnostic microbiology laboratories should perform antibiotic susceptibility tests in addition to tests for beta-lactamase production.
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PMID:Ampicillin treatment failure of apparently beta-lactamase-negative Haemophilus influenzae type b meningitis due to novel beta-lactamase. 611 76

The emergence of beta-lactamase producing strains of Haemophilus influenzae and Neisseria gonorrhoeae has required fundamental changes in the antimicrobial therapy of disease caused by these organisms. Ampicillin resistance in both organisms is caused by plasmid mediated production of TEM beta-lactamase. This enzyme is specified by a sequence of mol. wt 3.2 X 10(6) which is capable of inserting itself at multiple sites in DNA replicons without the requirement for significant base sequence homology between donor and recipient replicon. Further, it does so without requirement for conventional recombination enzymes. Analysis of beta-lactamase specifying plasmids of H. influenzae show that they generally have a molecular mass in the order of 30 X 10(6) and contain the complete TnA sequence. They are conjugative but are incapable of mobilizing smaller beta-lactamase plasmids. Previous studies have presented evidence suggesting that these plasmids may have evolved by insertion of the TnA sequence (perhaps introduced from enteric bacteria) into a phenotypically cryptic plasmid of mol. wt 27 X 10(6) resident in rare strains of H. influenzae. In this study, we review data showing a high degree of homology between the small (3--7 X 10(6) mol. wt), nonconjugative beta-lactamase specifying plasmids of N. gonorrhoeae, H. parainfluenzae and H. ducreyl and present new evidence that cryptic plasmids highly homologous to the beta-lactamase plasmids are present in many strains of H. parainfluenzae. This suggests that the small beta-lactamase specifying plasmids of H. parainfluenzae, H. ducreyi and N. gonorrhoeae may have arisen by insertion of TnA into phenotypically cryptic plasmids present in H. parainfluenzae.
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PMID:Evolution of antibiotic resistance plasmids in Neisseria gonorrhoeae and Haemophilus species. 631 45

The activity in vitro of the new parenteral penicillin, temocillin, was determined by an agar dilution technique at two inocula against 201 recent clinical isolates and also against reference strains that produced characterized beta-lactamases. Ampicillin, ticarcillin, latamoxef (moxalactam) and cefoxitin were used as comparative agents. Temocillin showed no useful activity against Pseudomonas aeruginosa or the Bacteroides fragilis group but was highly active against the Enterobacteriaceae, inhibiting all isolates (Serratia marcescens excepted) at less than or equal to 8 mg/l. The MIC50 and MIC90 were usually within one dilution and results with both inoculum sizes were similar. Temocillin also had good activity against Haemophilus influenzae and beta-lactamase producing strains were as susceptible as non-beta-lactamase producers. Neither for the Enterobacteriaceae nor for H. influenzae did a 1000-fold increase in inoculum result in a greater than two-fold increase in MIC. The above results implied excellent stability to beta-lactamases and this was borne out by the activity of temocillin against strains containing chromosomal cephalosporinases, the 'broad-spectrum' Class IV enzyme and the plasmid mediated enzymes TEM-1, OXA-1 and SHV-1. The protein binding of temocillin was found to be 87%.
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PMID:Comparative in-vitro activity of temocillin (BRL 17421), a new penicillin. 660 23

BRL 17421, a novel beta-lactam antibiotic, was tested in vitro against fastidious gram-negative bacteria and compared with amoxicillin and amoxicillin plus clavulanic acid. The compound showed good activity against Haemophilus influenzae (range of minimal inhibitory concentrations, 0.2 to 1 microgram/ml), Neisseria gonorrhoeae (0.007 to 0.5 microgram/ml), and Branhamella catarrhalis (0.03 to 0.1 microgram/ml). BRL 17421 exhibited excellent stability against the TEM-type beta-lactamase of H. influenzae and N. gonorrhoeae, and its activity was little affected by inoculum size. Minimal lethal concentrations of BRL 17421 for 10(7) colony-forming units of H. influenzae ranged between 0.5 and 4 micrograms/ml.
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PMID:In vitro activity of BRL 17421 against Haemophilus influenzae, Neisseria gonorrhoeae, and Branhamella catarrhalis. 680 22

Carriage of ampicillin-resistant (Ampr) Haemophilus parainfluenzae has become frequent among children in our community, although carriage of Ampr Haemophilus influenzae remains uncommon. In this study we characterized the mechanism of ampicillin resistance in 27 representative isolates of H. parainfluenzae. As determined by isoelectric focusing, each isolate had a TEM-1 beta-lactamase; substrate profiles assessed for enzymes from 10 strains were also consistent with TEM-1 enzyme. Agarose gel electrophoresis revealed a plasmid of 23 to 34 megadaltons in each isolate and a small plasmid (less than or equal to 4 megadaltons) in 14 isolates. Transfer of ampicillin resistance to H. influenzae Rd was achieved during membrane mating with 14 of 15 donors. The transconjugants exhibited high-level ampicillin resistance (greater than or equal to 50 micrograms/ml), which was stable despite serial passage of isolates on antibiotic-free media. The transconjugants tested retained fertility. Cryptic plasmids were discovered in 7 of 25 antibiotic-susceptible H. parainfluenzae isolates. Our data suggest that H. parainfluenzae may play an important role in the exchange of Ampr genes among throat bacteria.
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PMID:Characterization of ampicillin-resistant Haemophilus parainfluenzae. 698 Jun 26


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