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Query: UMLS:C0348321 (Haemophilus)
 15,372 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

There is poor correlation between the MICs and zone sizes obtained for erythromycin against Haemophilus influenzae. The effect of two media, Mueller-Hinton medium supplemented with 3% lysed horse blood and 10 micrograms of NAD per ml (MHA + LYHB) and Mueller-Hinton agar supplemented with 1% bovine hemoglobin and 1% IsoVitaleX (MHA + HGB), on the MICs and zone sizes of erythromycin against H. influenzae was determined. The effect of three different methods for inoculum preparation on the susceptibility of H. influenzae was also determined. The MICs were independent of the method of inoculum preparation, but the zone sizes were smaller if the inoculum was carefully adjusted to contain approximately 10(8) CFU/ml. MICs were higher and zone sizes were smaller when MHA + HGB was used instead of MHA + LYHB. Good correlation was found when MHA + LYHB was used for determining the MIC and MHA + HGB was used for determining susceptibility by the disk method. When the inoculum was adjusted to match a McFarland 0.5 standard, the viable counts had to be approximately 10(8) CFU/ml for good correlation between MICs and zone sizes. A-56268, a new macrolide antibiotic, was tested against H. influenzae, and its MICs and tentative breakpoints against this organism were determined. The MICs obtained by various methods were correlated with in vivo efficacy by using a mouse septicemia model. MICs obtained on MHA + HGB or MHA + LYHB incubated without a 5% CO2 atmosphere showed the best correlation with in vivo efficacy.
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PMID:Susceptibility testing of macrolide antibiotics against Haemophilus influenzae and correlation of in vitro results with in vivo efficacy in a mouse septicemia model. 295 54

The activity of chloramphenicol against 100 different strains of Haemophilus influenzae was assessed by a macrotube broth dilution technique and by a standardized disk diffusion method using both enriched chocolate agar (CHOC) and Mueller-Hinton agar containing 1.0% hemoglobin and 1.0% IsoVitaleX (BBL Microbiology Systems, Cockeysville, Md.) supplement (CHOC-MHA). Filter disks containing 30 micrograms of chloramphenicol were used with the disk diffusion procedure. The following zone diameter interpretive criteria were defined: CHOC-MHA, less than or equal to 25 mm = resistant [corrected] and greater than or equal to 26 mm = susceptible [corrected]; CHOC, less than or equal to 28 mm = resistant [corrected] and greater than or equal to 29 mm = susceptible [corrected]. all of the H. influenzae strains examined were also characterized by using two rapid assays for chloramphenicol acetyltransferase (CAT) activity: a 1-h tube method (t-CAT) and a 30-min procedure which used commercially available reagent-impregnated disks (d-CAT). The t-CAT procedure was found to be significantly more accurate than the d-CAT procedure as a means for demonstrating production of CAT.
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PMID:In vitro chloramphenicol susceptibility testing of Haemophilus influenzae: disk diffusion procedures and assays for chloramphenicol acetyltransferase. 349 44

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

Several agar media (Mueller-Hinton agar, MHA; diagnostic sensitivity test agar, DSTA; Schaedler agar, SchA; Todd-Hewitt agar with added yeast extract, THYA; Wilkins-Chalgren agar, WCA) were compared using the Bauer-Kirby agar disk diffusion test against six nonfastidious quality control strains: Staphylococcus aureus ATCC 25923 and ATCC 29213, Escherichia coli ATCC 25922 and ATCC 35218, Pseudomonas aeruginosa ATCC 27853, and Enterococcus faecalis ATCC 29212. MHA, DSTA, and THYA yielded essentially comparable inhibition zones. However, WCA and SchA antagonized cotrimoxazole and aminoglycoside antibiotics; furthermore, SchA antagonized polymyxin B, and both WCA and SchA antagonized imipenem against the P. aeruginosa strain, but not against the E. coli strains. Sheep blood-MHA (Bl-MHA), WCA, THYA, and DSTA were examined with Streptococcus pyogenes ATCC 19615, Streptococcus agalactiae ATCC 13813, and Streptococcus pneumoniae ATCC 6306. In comparison with Bl-MHA, both WCA and THYA yielded comparable inhibition zones against S. pyogenes; DSTA afforded suboptimal growth. DSTA yielded larger inhibition zones with the majority of antimicrobial drugs against S. agalactiae, whereas WCA and THYA enhanced the activity of oxacillin and penicillin G against this strain. S. pneumoniae strain ATCC 6306 grew well on Bl-MHA, yielded suboptimal growth on WCA and faint growth on THYA, and failed to grow on DSTA. Chocolate-supplemented sheep blood-MHA (CHOC-MHA) was compared with Haemophilus test medium (HTM), WCA with added NAD, and THYA with added hematin and NAD against Haemophilus influenzae strains ATCC 35056 and ATCC 49247. The activities of doxycycline and rifampin were enhanced against both strains by HTM, WCA+NAD, and THYA+hematin+NAD. Only WCA+NAD antagonized cotrimoxazole against both H. influenzae strains, an effect due to thymidine; however, HTM antagonized cotrimoxazole against S. aureus ATCC 25923 and E. coli ATCC 25922. It was concluded that Bl-MHA performed best for beta-hemolytic streptococci quality control strains. Likewise, CHOC-MHA was optimal for the two H. influenzae strains used in this comparative agar disk diffusion study.
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PMID:Agar disk diffusion (Bauer-Kirby) tests with various fastidious and nonfastidious reference (ATCC) strains: comparison of several agar media. 784 20

Quinupristin/dalfopristin and RPR 106972 were active in vitro against a wide range of aerobic Gram-positive organisms including Enterococcus faecium. However, most isolates of Enterococcus faecalis were resistant or of intermediate sensitivity. Against Staphylococcus aureus quinupristin/dalfopristin was more active but for all other species the range of activity of the two drugs was the same or RPR 106972 was more active. RPR 106972 was also more active against the respiratory pathogens Haemophilus influenzae and Moraxella catarrhalis. Quinupristin/dalfopristin MICs for isolates of H. influenzae (1-8 mg/L) clustered around the breakpoint. There were differences in the quality of growth, but little difference in MICs or zone diameters was obtained on three different media: Mueller-Hinton (MHA), Iso-Sensitest (ISA), and Diagnostic Sensitivity Test (DST) agars. The addition of blood to the medium increased MICs 2- to 4-fold, with MHA showing the greatest increase, and reduced zone diameters around quinupristin/dalfopristin discs by 3-4 mm, with the greatest effect on ISA.
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PMID:Comparative activity of quinupristin/dalfopristin and RPR 106972 and the effect of medium on in-vitro test results. 1005 93