Simplified Medium for Ampicillin Susceptibility Testing of
            <i>Haemophilus influenzae</i>

Jorgensen, James H.; Jones, Pamela M.

doi:10.1128/aac.7.2.186

Cited by 19 publications

(17 citation statements)

References 8 publications

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“…In this study we compared a new method for testing the antibiotic susceptibility of H. influenzae (NRA) with a standard 'micro-broth-di- (5) and agar dilution techniques (3,15), further supporting the validity of the NRA.…”

Section: Discussionmentioning

confidence: 99%

“…The appearance of ampicillin-and chloramphenicol-resistant strains of Haemophilus influenzae (9,14) has stimulated interest in developing better techniques for assaying the antimicrobial susceptibility of these fastidious bacteria (5,6). Broth dilution assays, though commonly employed to measure both the minimal inhibitory concentration (MIC) and minimal bactericidal concentration (MBC) of antimicrobial agents, can be used to test the susceptibility of H. influenzae only if the medium is supplemented with hemin and nicotinamide adenine dinucleotide.…”

mentioning

confidence: 99%

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Nitrate Reduction: New Method for Testing the Antibiotic Susceptibility of Haemophilus influenzae

Fleming

Fierer

1978

Antimicrob Agents Chemother

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We have developed a new micro-broth-dilution assay for determining the antimicrobial susceptibility of Haemophilus influenzae. This assay is based on the ability of viable H. influenzae to reduce nitrates to nitrites. Bacterial viability is detected by a positive nitrite reaction rather than visible turbidity. The nitrate reduction assay was compared with a standard microassay using 51 isolates of H. influenzae and six beta-lactam antibiotics. Although there was good agreement between the two methods, the nitrate reduction assay was more sensitive in detecting viable bacteria, and so established a more accurate estimate of the minimal inhibitory concentration. The nitrate reduction assay offered the additional advantage that it could be used to determine the minimal bactericidal concentration without having to subculture the broth. Ampicillin, penicillin, and cefamandole were equally effective in vitro against susceptible strains (minimal inhibitory concentrations, 0.125 to 0.5 ,g/ml), whereas all three antibiotics were ineffective against two beta-lactamase-producing strains. Using the nitrate reduction assay, resistance to cefamandole was detectable with inoculum sizes ranging from 104 to 106 colony-forming units per ml, while the turbidity assay detected resistance only with the largest inoculum.The appearance of ampicillin-and chloramphenicol-resistant strains of Haemophilus influenzae (9, 14) has stimulated interest in developing better techniques for assaying the antimicrobial susceptibility of these fastidious bacteria (5, 6). Broth dilution assays, though commonly employed to measure both the minimal inhibitory concentration (MIC) and minimal bactericidal concentration (MBC) of antimicrobial agents, can be used to test the susceptibility of H. influenzae only if the medium is supplemented with hemin and nicotinamide adenine dinucleotide. Some broths will support the growth of H. influenzae, but even under good growth conditions turbidity may be difficult to detect (4, 7).We have developed a new assay procedure for testing the antimicrobial susceptibility of H. influenzae. The assay is based on the nitrate reductase activity of viable H. influenzae and the resultant production of nitrite (4, 16). Our method has the distinct advantage of increased reproducibility and accuracy, since the MIC is indicated by a color reaction, which is more easily detected than turbidity. This report includes a description of the assay and the results obtained with several beta-lactam antibiotics. MATERIALS AND METHODSBacteria. Fifty-one isolates of H. influenzae were tested. Thirty-nine isolates were smooth, nontypable H. influenzae recovered from sputum specimens submitted to the bacteriology laboratory, San Diego Veterans Administration Hospital. Ten isolates from various clinical specimens were classified serologically as type B and were ampicillin susceptible. Two strains were ampicillin-resistant, beta-lactamase-producing type B strains; one was obtained from Clyde Thornsberry, Center for Disease Control, Atlanta, Ga., ...

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Section: Discussionmentioning

confidence: 99%

mentioning

confidence: 99%

Nitrate Reduction: New Method for Testing the Antibiotic Susceptibility of Haemophilus influenzae

Fleming

Fierer

1978

Antimicrob Agents Chemother

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“…1,1988 is simple to prepare. It has been used successfully in broth and agar dilution testing as well as for disk diffusion assays (46,48). However, it has only been evaluated for differentiating ampicillin-susceptible strains from beta-lactamase-producing strains.…”

Section: Susceptibility Testingmentioning

confidence: 99%

Haemophilus influenzae: antibiotic susceptibility

Needham

1988

Clin Microbiol Rev

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Ampicillin resistance was first reported among clinical isolates of Haemophilus influenzae in 1972. Reports of chloramphenicol resistance followed shortly thereafter. The principal mechanism of resistance to these two antibiotics is enzymatic. Although other mechanisms have been described, they are found in comparatively few strains. The genetic information for the inactivating enzymes is plasmid mediated and therefore readily transmissible to susceptible strains. Consequently, effective therapy for invasive disease caused by this pathogen has been seriously compromised. As antibiotic susceptibility became less predictable, in vitro testing became increasingly important. Unfortunately, the standardization of methods for laboratory testing has been slow and complicated by the fastidious nature of the organisms. This review traces the development of antibiotic resistance in H. influenzae, discusses the mechanisms which appear to be important in mediating resistance, explores newer antimicrobial agents which might be useful in the treatment of infection, and analyzes the various approaches to in vitro testing.

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“…The widening spectrum of Haemophilus influenzae infections affecting both young children (8) and healthy adults (23) and the emergence of strains resistant to ampicillin (14,21,27) have stimulated investigators to study the in vitro efficacy of other antimicrobial agents against this microorganism (4,11,12,20,30).…”

mentioning

confidence: 99%

“…Most of the 25 beta-lactamaseproducing H. influenzae were resistant to 128 yg of ampicillin per ml. Both moxalactam and chloramphenicol, which had minimal inhibitory concentrations of less than 0.25 and 2 jig/ml, respectively, were more active than cefamandole, which had a minimal inhibitory concentration ranging from 2 to 2128 ,ug/ml.The widening spectrum of Haemophilus influenzae infections affecting both young children (8) and healthy adults (23) and the emergence of strains resistant to ampicillin (14,21,27) have stimulated investigators to study the in vitro efficacy of other antimicrobial agents against this microorganism (4,11,12,20,30).On the basis of these observations, cefamandole has been suggested as a useful cephalosporin for H. influenzae infections other than those affecting the central nervous system (3,6,9,25,26), but its clinical efficacy in infections due to ampicillin-or chloramphenicol-resistant strains has yet to be confirmed on a large scale.In the present study, we report the comparative in vitro activity of moxalactam, a new semisynthetic 1-oxa-beta-lactam (28, 31), cefamandole lithium, ampicillin, and chloramnphenicol. …”

mentioning

confidence: 99%

Limited in vitro activity of cefamandole against 100 beta-lactamase- and non-beta-lactamase-producing Haemophilus influenzae strains: comparison of moxalactam, chloramphenicol, and ampicillin

Bergeron¹,

Claveau²,

Simard³

1981

Antimicrob Agents Chemother

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In the present study, the minimal inhibitory concentrations and minimal bactericidal concentrations of moxalactam, cefamandole lithium, ampicillin, and chloramphenicol were determined, both in broth and on solid medium, against 75 non-beta-lactamase-producing and 25 beta-lactamase-producing strains of Haemophilus influenzae. Most of the 75 strains were inhibited or killed by 2 ,jg or less of ampicillin, chloramphenicol, or moxalactam per ml, but cefamandole exhibited poor bactericidal activity against 11 non-beta-lactamase-producing strains, of which 9 were non-type B H. influenzae. Most of the 25 beta-lactamaseproducing H. influenzae were resistant to 128 yg of ampicillin per ml. Both moxalactam and chloramphenicol, which had minimal inhibitory concentrations of less than 0.25 and 2 jig/ml, respectively, were more active than cefamandole, which had a minimal inhibitory concentration ranging from 2 to 2128 ,ug/ml.The widening spectrum of Haemophilus influenzae infections affecting both young children (8) and healthy adults (23) and the emergence of strains resistant to ampicillin (14,21,27) have stimulated investigators to study the in vitro efficacy of other antimicrobial agents against this microorganism (4,11,12,20,30).On the basis of these observations, cefamandole has been suggested as a useful cephalosporin for H. influenzae infections other than those affecting the central nervous system (3,6,9,25,26), but its clinical efficacy in infections due to ampicillin-or chloramphenicol-resistant strains has yet to be confirmed on a large scale.In the present study, we report the comparative in vitro activity of moxalactam, a new semisynthetic 1-oxa-beta-lactam (28, 31), cefamandole lithium, ampicillin, and chloramnphenicol.

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Simplified Medium for Ampicillin Susceptibility Testing of Haemophilus influenzae

Cited by 19 publications

References 8 publications

Nitrate Reduction: New Method for Testing the Antibiotic Susceptibility of Haemophilus influenzae

Nitrate Reduction: New Method for Testing the Antibiotic Susceptibility of Haemophilus influenzae

Haemophilus influenzae: antibiotic susceptibility

Limited in vitro activity of cefamandole against 100 beta-lactamase- and non-beta-lactamase-producing Haemophilus influenzae strains: comparison of moxalactam, chloramphenicol, and ampicillin

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