Manner and meaning of susceptibility testing of ampicillin-resistant Haemophilus influenzae. 1977

B M Gray, and C A Hubbell, and H C Dillon

We examined ampicillin-resistant strains of Haemophilus influenzae to compare the percentage of resistant organisms in each strain with the susceptibility to ampicillin by an agar dilution method. Using an inoculum of 10(4) colony-forming units, the minimal inhibitory concentration (MIC) increased with the percentage of resistant organisms in the strain. Laboratory-manipulated strains composed of different proportions of a susceptible and a resistant strain behaved similarly. The survival of isolated colony-forming units (colony MIC) was then determined by spreading inocula over the surface of a set of MIC plates, resulting in separation of individual colonies. This modification of the susceptibility test to the colony level gave end points that were clear and reproducible and that did not vary with changes in incubation time or temperature. True differences in susceptibility among strains were demonstrated by this method, whereas results of the conventional MIC test may reflect only the number of resistant organisms present in the inoculum.

UI MeSH Term Description Entries
D008826 Microbial Sensitivity Tests Any tests that demonstrate the relative efficacy of different chemotherapeutic agents against specific microorganisms (i.e., bacteria, fungi, viruses). Bacterial Sensitivity Tests,Drug Sensitivity Assay, Microbial,Minimum Inhibitory Concentration,Antibacterial Susceptibility Breakpoint Determination,Antibiogram,Antimicrobial Susceptibility Breakpoint Determination,Bacterial Sensitivity Test,Breakpoint Determination, Antibacterial Susceptibility,Breakpoint Determination, Antimicrobial Susceptibility,Fungal Drug Sensitivity Tests,Fungus Drug Sensitivity Tests,Sensitivity Test, Bacterial,Sensitivity Tests, Bacterial,Test, Bacterial Sensitivity,Tests, Bacterial Sensitivity,Viral Drug Sensitivity Tests,Virus Drug Sensitivity Tests,Antibiograms,Concentration, Minimum Inhibitory,Concentrations, Minimum Inhibitory,Inhibitory Concentration, Minimum,Inhibitory Concentrations, Minimum,Microbial Sensitivity Test,Minimum Inhibitory Concentrations,Sensitivity Test, Microbial,Sensitivity Tests, Microbial,Test, Microbial Sensitivity,Tests, Microbial Sensitivity
D010405 Penicillinase A beta-lactamase preferentially cleaving penicillins. (Dorland, 28th ed) EC 3.5.2.-. beta-Lactamase I,AER-I beta-Lactamase,Benzylpenicillinase,Carbenicillinase,Exopenicillinase,beta Lactamase III,beta Lactamase RP4,gamma-Penicillinase,AER I beta Lactamase,Lactamase RP4, beta,beta Lactamase I,beta-Lactamase, AER-I,gamma Penicillinase
D002999 Clone Cells A group of genetically identical cells all descended from a single common ancestral cell by mitosis in eukaryotes or by binary fission in prokaryotes. Clone cells also include populations of recombinant DNA molecules all carrying the same inserted sequence. (From King & Stansfield, Dictionary of Genetics, 4th ed) Clones,Cell, Clone,Cells, Clone,Clone,Clone Cell
D006193 Haemophilus influenzae A species of HAEMOPHILUS found on the mucous membranes of humans and a variety of animals. The species is further divided into biotypes I through VIII. Bacterium influenzae,Coccobacillus pfeifferi,Haemophilus meningitidis,Hemophilus influenzae,Influenza-bacillus,Mycobacterium influenzae
D000667 Ampicillin Semi-synthetic derivative of penicillin that functions as an orally active broad-spectrum antibiotic. Penicillin, Aminobenzyl,Amcill,Aminobenzylpenicillin,Ampicillin Sodium,Ampicillin Trihydrate,Antibiotic KS-R1,Omnipen,Pentrexyl,Polycillin,Ukapen,Aminobenzyl Penicillin,Antibiotic KS R1,KS-R1, Antibiotic,Sodium, Ampicillin,Trihydrate, Ampicillin
D013045 Species Specificity The restriction of a characteristic behavior, anatomical structure or physical system, such as immune response; metabolic response, or gene or gene variant to the members of one species. It refers to that property which differentiates one species from another but it is also used for phylogenetic levels higher or lower than the species. Species Specificities,Specificities, Species,Specificity, Species

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