Influence of growth medium and supplement on growth of Haemophilus influenzae and on antibacterial activity of several antibiotics.
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.
D000667:Ampicillin / Q000494:pharmacology; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D002435:Cefamandole / Q000494:pharmacology; D002438:Cefoperazone / Q000494:pharmacology; D002701:Chloramphenicol / Q000494:pharmacology; D003470:Culture Media; D004338:Drug Combinations; D004917:Erythromycin / Q000494:pharmacology; D005839:Gentamicins / Q000494:pharmacology; D006193:Haemophilus influenzae / Q000187:drug effects / Q000254:growth & development*; D008826:Microbial Sensitivity Tests; D013420:Sulfamethoxazole / Q000494:pharmacology; D013752:Tetracycline / Q000494:pharmacology; D014295:Trimethoprim / Q000494:pharmacology; D015662:Trimethoprim, Sulfamethoxazole Drug Combination
D000900:Anti-Bacterial Agents; D003470:Culture Media; D004338:Drug Combinations; D005839:Gentamicins; D002435:Cefamandole; D004917:Erythromycin; D002701:Chloramphenicol; D000667:Ampicillin; D002438:Cefoperazone; D015662:Trimethoprim, Sulfamethoxazole Drug Combination; D014295:Trimethoprim; D013752:Tetracycline; D013420:Sulfamethoxazole