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Query: UNIPROT:Q29983 (MIC)
 21,138 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

During antibiotic therapy for serious Haemophilus influenzae type b infections in children, respiratory mucosal colonization with this organism is suppressed but not eradicated. To define possible mechanisms contributing to this suppression, the ability of six antibiotics to influence the adherence of H. influenzae type b to human epithelial cells was investigated. In assays in which the organisms were grown in broth containing 0.5 X the MIC of rifampin, ampicillin, clindamycin, chloramphenicol, lincomycin, or trimethoprim-sulfamethoxazole, all drugs except rifampin significantly reduced bacterial adherence. In assays in which nonreplicating organisms were exposed to the antibiotics, all six drugs reduced the adherence of the bacteria. In assays in which the epithelial cells were exposed to the antibiotics, all drugs reduced bacterial adherence. In addition, the presence of ampicillin, chloramphenicol, lincomycin, or trimethoprim-sulfamethoxazole appeared to facilitate the release of organisms adherent to epithelial cells. Thus, antibiotics appear to inhibit adherence of H. influenzae type b to human epithelial cells and may interfere with bacterial or epithelial cell binding sites. These observations may explain the suppression of H. influenzae type b mucosal colonization that occurs during antibiotic treatment of patients with systemic H. influenzae type b infections.
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PMID:Effect of antibiotics on adherence of Haemophilus influenzae type b. 349 Aug 26

In the present study, five non-beta-lactamase- and five beta-lactamase-producing strains of Haemophilus influenzae were used to determine whether three different growth media, Mueller-Hinton broth and agar, brain heart infusion broth and agar, and tryptic soy broth and agar, and their added supplements (0.2% hemin-0.1% IsoVitaleX, 1% hemin-1% IsoVitaleX, 2% sheep blood, 10% Fildes enrichment, 5% Fildes enrichment, 1% supplement B, 5% horse erythrocytes, and 2% hemoglobin-1% IsoVitaleX) would influence the growth rate of this microorganism and the antibacterial activity of eight antibiotics, including ampicillin, tetracycline, chloramphenicol, gentamicin, cefamandole, erythromycin, trimethoprim-sulfamethoxazole (TMP-SMX), and cefoperazone. The growth curve studies were carried out with an initial inoculum of 10(4) bacteria per ml, and MICs were determined with an inoculum of 5 X 10(5) microorganisms. Mueller-Hinton broth, brain heart infusion broth, and tryptic soy broth enriched with 5% Fildes resulted in a maximal growth of more than 10(8) CFU/ml at 24 h. When 10% Fildes or 2% sheep blood was added as enrichment to Mueller-Hinton broth, a considerable reduction in the growth rate of H. influenzae strains resulted (P less than 0.01). Significant variations in MICs (P less than 0.01) were observed with chloramphenicol, TMP-SMX, erythromycin, and cefoperazone when brain heart infusion agar, Mueller-Hinton agar, or tryptic soy agar was used. Chloramphenicol, gentamicin, erythromycin, and TMP-SMX were all affected by the different enrichments added to Mueller-Hinton agar. MICs were in general higher with 5% Fildes enrichment and lower with 1% supplement B. Cefoperazone was the only drug which exhibited a lower MIC in 5% Fildes enrichment for ampicillin-resistant H. influenzae strains.
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PMID:Influence of growth medium and supplement on growth of Haemophilus influenzae and on antibacterial activity of several antibiotics. 349 45

It has become increasingly important to perform routine susceptibility tests on certain anaerobic bacteria, Haemophilus influenzae and Streptococcus pneumoniae, as a result of the decreasing predictability of their antimicrobial susceptibility patterns. The antimicrobial susceptibilities of 49 anaerobic isolates, 25 H. influenzae isolates, and 25 S. pneumoniae isolates were determined concurrently by API Uniscept MIC trays and a conventional broth microdilution method using Wilkins-Chalgren broth, 5% Fildes in Schaedler broth, or 5% lysed horse blood in Mueller-Hinton broth, respectively. Analysis of 490 anaerobic organism-antibiotic combinations, 144 H. influenzae-antibiotic combinations, and 125 S. pneumoniae-antibiotic combinations showed that 98.9%, 100%, and 99.2%, respectively, of the API results were within +/- 1 log2 dilution of the reference system. The API Uniscept MIC panel would be acceptable for use as a routine susceptibility system for anaerobic organisms in a clinical microbiology laboratory. To eliminate trailing endpoints, however, further studies need to be performed to evaluate additional broth media for the susceptibility testing of H. influenzae and S. pneumoniae in the API panels.
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PMID:Susceptibility testing of fastidious organisms in the API microdilution panel. 349 93

Penicillin-binding protein (PBP) alterations have been associated with non-beta-lactamase-mediated ampicillin resistance in Haemophilus influenzae. We evaluated the PBP profiles of several ampicillin-susceptible and -resistant clinical isolates of H. influenzae to determine how consistently the described alterations occurred, and to document the reproducibility of the PBP profiles for this species. The MIC of ampicillin ranged from 0.06 to 0.13 microgram ml-1 for the susceptible isolates at an inoculum of 100,000 c.f.u. when tested by broth dilution, and was 0.5 microgram ml-1 for all four isolates when tested by agar dilution. The MIC for the resistant isolates ranged from 4 to 8 micrograms ml-1 when tested by broth dilution, and from 1.5 to 16 micrograms ml-1 when tested by agar dilution. At least eight distinct PBPs with molecular masses ranging from 27 to 90 kDa were detected both in cell membrane preparations and whole cell (in vivo) binding assays done on cells in the exponential growth phase. PBP variability was evident both in the ampicillin-susceptible and -resistant isolates; however, much greater variability existed within the four resistant strains. The differences in PBP patterns included (1) electrophoretic mobility, (2) binding capacity for the antibiotic and (3) the presence of additional PBPs in two of the resistant isolates. However, decreased binding capacity was consistently demonstrated in PBP 5 (56 kDa) of all of the resistant isolates. Saturation curves with both penicillin and ampicillin indicated that PBP 5 had decreased affinity for the antibiotics.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Ampicillin resistance and penicillin-binding proteins of Haemophilus influenzae. 349 5

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

A new semisynthetic oral cephalosporin, BMY-28100, was evaluated for in vitro and in vivo antibacterial activities in comparison with cefaclor and cephalexin. BMY-28100 showed in vitro activity 3- and 10-fold more potent than that of cefaclor against Staphylococcus aureus and Streptococcus pneumoniae, respectively. BMY-28100 was slightly better than cefaclor and about 4 times more active than cephalexin against Haemophilus influenzae and Neisseria gonorrhoeae. Escherichia coli, Klebsiella pneumoniae and Proteus mirabilis were comparably susceptible to BMY-28100 and cefaclor. The bactericidal activity of BMY-28100 against S. aureus, E. coli and P. mirabilis was equal to or twice as high as MIC value, which was similar to that of cefaclor. The stability of BMY-28100 against penicillinases was nearly comparable to that of cefaclor, whereas cefaclor was somewhat unstable to cephalosporinases. BMY-28100 was about twice as active as cefaclor against three Gram-positive bacterial infections. BMY-28100 was also more potent against infections of H. influenzae and P. mirabilis, but slightly less active against E. coli Juhl than cefaclor. Blood level parameters of BMY-28100 were significantly superior to those of cefaclor and slightly better than cephalexin in mice and rats. The urinary recovery of BMY-28100 was somewhat higher and comparable to that of cefaclor and cephalexin, respectively. BMY-28100 was more stable than cefaclor in human and calf sera at 37 degrees C.
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PMID:In vitro and in vivo evaluations of BMY-28100, a new oral cephalosporin. 350 Jan 58

The need for complex growth media has complicated routine susceptibility testing of Haemophilus influenzae because of antagonism of certain antimicrobial agents by the medium or because of difficulties in interpretation of growth endpoints. Haemophilus test medium (HTM) is a simple, transparent medium for broth- or agar-based tests with H. influenzae. HTM incorporates Mueller-Hinton medium with additions of 15 micrograms of hematin per ml, 15 micrograms of NAD per ml, and 5 mg of yeast extract per ml as growth-promoting additives. Agar or broth microdilution MICs of 10 antimicrobial agents for a collection of 179 H. influenzae isolates determined by using HTM compared favorably with MICs determined by the conventional agar or broth dilution methods recommended by the National Committee for Clinical Laboratory Standards. Disk diffusion tests performed with HTM allowed accurate categorization of susceptible and resistant strains and were easier to interpret than tests performed with Mueller-Hinton chocolate agar. A particular advantage of HTM was the reliability of broth- or agar-based test results with trimethoprim-sulfamethoxazole. The results of the study suggest modification of current National Committee for Clinical Laboratory Standards MIC-interpretive criteria for H. influenzae with amoxicillin-clavulanate, chloramphenicol, and trimethoprim-sulfamethoxazole. Error rate-bounded analysis of MICs and disk diffusion zone sizes also suggest modified zone-interpretive criteria for ampicillin, amoxicillin-clavulanate, chloramphenicol, and tetracycline with HTM or conventional media. Interpretive zone sizes are newly proposed for cefaclor and rifampin disk diffusion tests.
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PMID:Improved medium for antimicrobial susceptibility testing of Haemophilus influenzae. 350 Sep 65

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

Two hundred and fifty-seven ampicillin-resistant clinical isolates of Haemophilus influenzae were tested by disk diffusion and MIC determination for susceptibility to aztreonam, imipenem, and amoxycillin combined with clavulanate. The modal MICs and MICs for 50 and 90% of isolates of all three antimicrobial agents for the 157 beta-lactamase-positive strains did not differ significantly from figures obtained with 2,201 ampicillin-susceptible H. influenzae by the same methods. Aztreonam and amoxycillin-clavulanate were less active, as reflected by an increase in these parameters, against 38 beta-lactamase-negative isolates requiring greater than or equal to 4 micrograms of ampicillin per ml for inhibition and 62 strains considered to have an intermediate degree of nonenzymic (intrinsic) resistance to ampicillin (zone diameters of less than 20 mm with 2-micrograms ampicillin disks and MICs of 1 or 2 micrograms/ml). There was no detectable difference in imipenem activity against these 100 strains compared with that observed against the ampicillin-susceptible group. Of the 24 strains requiring at least 4 micrograms of imipenem per ml for inhibition, 13 also showed reduced susceptibility to ampicillin (5 beta-lactamase-positive and 8 beta-lactamase-negative isolates). A lack of correlation between reduced susceptibility to imipenem and the other beta-lactams was observed.
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PMID:In vitro activities of aztreonam, imipenem, and amoxycillin-clavulanate against ampicillin-resistant Haemophilus influenzae. 350 40

The prevalence of antimicrobial resistance among clinical isolates of Haemophilus influenzae was assessed in France. A total of 705 isolates, obtained from CSF (98 strains), blood (76), ears (118), eyes (164), lower respiratory tract specimens (144), genital specimens (28), and various other specimens (71) were examined. These isolates were obtained from microbiological laboratories distributed throughout France and were sent to the Center for the study of H. influenzae during one year. Biotype of isolates was determined by use of API 10 E system and serotype was determined by slide agglutination procedure. All isolates were examined for beta-lactamase production with a chromogenic test. Susceptibility to ampicillin, cefotaxime, gentamicin, kanamycin, chloramphenicol, tetracycline, minocycline, erythromycin and rifampicin was determined by disk diffusion test and MIC determination by agar dilution procedure. Drug resistance was observed for 92 strains (13%). The overall resistance was 11.2% to ampicillin (all but one strain were beta-lactamase producers), 9% to tetracycline (Tc), 3.4 to chloramphenicol (Cm) and 6.8% to kanamycin (Km). Eleven phenotypes of resistance were observed: the most frequently observed were Ap-Km-Tc, Ap, Ap-Km-Cm-Tc, Ap-Tc, Ap-Km, Tc. Antimicrobial resistance rates varied by specimens: resistance to ampicillin concerned 12.2% of the strains from CSF, 10.5% from blood, 12.5% from sputum, 16.1% from ears, 6.7% from eyes; tetracycline resistance concerned 14.2%, 10.5%, 10.4%, 7.6% and 4.8% of the same strains respectively; resistance to chloramphenicol concerned 4%, 5.2%, 1.3%, 3.3% and 2.4% of the strains respectively.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:[Prevalence of antibiotic resistance of Haemophilus influenzae isolated in France: a year of activities of the network of surveillance for H. influenzae infections]. 353 9


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