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

Ampicillin-resistant Haemophilus influenzae type B have been reported only during the past year. Five clinical isolates from the U.S. and Germany all had the TEM-type beta-lactamase which is known to be transferred widely among other gram-negative bacilli. Unlike those bacilli, however, the H. influenzae cell had very little barrier to entry of penicillins. This greater permeability of the H. influenzae cell to penicillins appeared to reduce the protective effect of its beta-lactamase, in that acquisition of the TEM-type beta-lactamase increased levels of resistance to penicillins much less for individual cells of H. influenzae than for those of Escherichia coli. Large inocula of either species appeared highly resistant. The unusually low level of resistance of individual cells of H. influenzae containing the TEM-type beta-lactamase may have delayed their emergence or recognition, and has unresolved clinical implications.
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PMID:Ampicillin-resistant Haemophilus influenzae type B possessing a TEM-type beta-lactamase but little permeability barrier to ampicillin. 4 83

The ability of Haemophilus equigenitalis, the causal agent of contagious equine metritis 1977, to survive in various antibiotic-containing semen extenders was studied at different environmental temperatures. Gentamicin sulphate was found to be markedly superior to ampicillin or a combination of sodium benzyl penicillin and polymyxin B sulphate, Semen treated with the former antibiotic was either sterile at cultural examination or else yielded appreciably fewer colonies of H. equigenitalis than the untreated semen control. Ampicillin had no observable effect on the survival of this organism. Gentamicin was most effective when semen-extender mixtures were held at room temperature rather than at 37 or 4 degrees C. No detrimental effects on sperm motility were observed following the use of the different antibiotic-containing semen extenders in the presence or absence of H. equigenitalis.
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PMID:Survival of Haemophilus equigenitalis in different antibiotic-containing semen extenders. 28 12

Rarely is endocarditis attributed to the species of Hemophilus. Most frequently implicated are H aphrophilus and H parainfluenzae, but H influenzae also is seen. We report six cases of endocarditis due to H aphrophilus or H parainfluenzae and review the literature. Emboli to skin, lungs, kidneys, spleen, brain, and other organs are common complications, and acute glomerulonephritis and meningitis often occur. Ampicillin is the mainstay of antimicrobial therapy for patients whose isolates are sensitive to it, but the duration of antimicrobial therapy necessary for eradication of the infection is not clear. Studies of antimicrobial synergism are warranted in instances of endocarditis caused by ampicilin- or penicillin-resistant strains of Hemophilus, or when patients are allergic to penicillin; in these instances, combination antimicrobial therapy must be given when bactericidal synergism can be demonstrated. Intensive management of complications caused by embolization is crucial to patient survival.
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PMID:Hemophilus endocarditis: new cases, literature review and recommendations for management. 30 87

We evaluated the inhibitory effect of trimethoprim (TMP) and sulfamethoxazole (SMZ), alone and in combination, against 34 strains of Haemophilus influenzae. Growth inhibition was determined after incubation for 18 h by comparing viable counts of cultures in drug-containing medium with corresponding counts of control cultures in drug-free medium. In a modified, thymidine-deficient Levinthal broth, the numbers of colony-forming units of all the isolates tested were reduced 100-fold or more by TMP/SMZ (1.25/25 mug/ml) as compared with growth without drug. Inhibition was significantly greater with TMP/SMZ than with either TMP or SMZ alone. Ampicillin-susceptible and ampicillin-resistant strains were equally susceptible to TMP/SMZ. Growth of nontypable strains was inhibited more than growth of type b organisms.
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PMID:Quantitative inhibition of Haemophilus influenzae by trimethoprim/sulfamethoxazole. 30 86

Ampicillin-resistant Hemophilus influenzae had not been identified in Fresno, California, before June 1976. In the 12 months that followed, eight resistant type B strains and three resistant nontypable isolates were cultured from patients treated at two hospitals that provide nearly all of the acute pediatric inpatient care for the area. Two of the resistant strains were obtained from patients with invasive infections and represented 4.2 percent of Hemophilus influenzae isolated from blood, cerebrospinal fluid or joint aspirates during the 12 months. The remaining six resistant type B strains were obtained from 117 patients, and were the predominant organism in cultures of other sites, primarily respiratory secretions. In two of three patients infected with nontypable organisms, resistance appeared to emerge during therapy with ampicillin. Measurement of beta lactamase was a practical and accurate method for differentiating between ampicillin-sensitive and resistant strains. All ten of the beta lactamase-positive isolates tested had minimal inhibitory concentrations (MIC) for ampicillin of 15 mug per ml, or less. In contrast 30 beta lactamase-negative strains had MIC's of 1.5 mug per ml, or less, of ampicillin. Our results indicate that ampicillin resistance has become a significant problem in the Central Valley of California and probably the entire state.
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PMID:Ampicillin-resistant Hemophilus influenzae. 30 57

Ampicillin-resistant Haemophilus influenzae does occur now in the FRG. In one isolate a plasmid with resistance genes (R-factor) could be demonstrated as cause of the ampicillin resistance. This R-factor influences production of a beta-lactamase of the TEM type which destroys ampicillin. The infectious nature of the ampicillin resistance was proven by the fact that it was transferable to other bacterial species through cocultivation. Parallel to ampicillin resistance tetracycline resistant Haemophilus influenzae has occurred in the FRG. Here the resistance was equally bound to plasmids. These R-factors are infectious as well. Molecular analysis of the 3 isolated resistance factors in Haemophilus influenzae showed that they carry the same resistance genes which are known from R-factors of Enterobacteriaceae. In the therapy of purulent infections due to Haemophilus influenzae such as childhood meningitis one can no longer rely on general ampicillin sensitivity of the offender. Apart from ampicillin and tetracycline resistant Haemophilus influenzae chloramphenicol resistance has been observed in a few cases.
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PMID:[Infectious resistance to antibiotics in Haemophilus influenzae (author's transl)]. 30 40

The comparative activities of ampicillin, cefamandole, cefoxitin, cefaclor, and cefatrizine against both beta-lactamase-producing and non-beta-lactamase-producing isolates of Haemophilus influenzae were determined by using an agar dilution susceptibility test procedure. Ampicillin was the most active drug tested against non-beta-lactamase-producing isolates, whereas cefamandole was most active against beta-lactamase-producing strains.
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PMID:Comparative activities of selected beta-lactam antibiotics against Haemophilus influenzae. 30 21

The in vitro activity of cefamandole was determined against 58 isolates of Haemophilus influenzae type b; 47 were beta-lactamase-negative (ampicillin-susceptible), and 11 produced beta-lactamase (ampicillin-resistant). Ampicillin-susceptible strains were susceptible to cefamandole with a median minimal bactericidal concentration (MBC) of 0.4 microgram/ml. Ampicillin-resistant strains had a median MBC of 0.8 microgram/ml. Prior studies have documented these concentrations of cefamandole in cerebrospinal fluid in the presence of inflamed meninges. Three children with meningitis due to H. influenzae type b were treated with cefamandole (200 mg/kg per day), including one child with disease due to an ampicillin-resistant strain. All patients showed clinical improvement during therapy. However, sterility of the cerebrospinal fluid was never achieved in two patients during 72--96 hr of therapy with cefamandole. The third patient relapsed with a recurrence of positive cultures during the seventh day of cefamandole therapy. Therefore, cefamandole does not appear to be a useful agent for treatment of meningitis due to H. influenzae type b irrespective of in vitro susceptibility or evidence of penetration into the cerebrospinal fluid.
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PMID:Failure of cefamandole in treatment of meningitis due to Haemophilus influenzae type b. 30 3

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 mug/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 10(4) to 10(6) colony-forming units per ml, while the turbidity assay detected resistance only with the largest inoculum.
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PMID:Nitrate reduction: new method for testing the antibiotic susceptibility of Haemophilus influenzae. 30 65

The emergence of resistance to ampicillin and other antibiotics in Haemophilus influenzae has been a relatively recent event. In contrast, drug resistance has been rampant in the Enterobacteriaceae for many years. Ampicillin-resistance in H. influenzae is almost invariably attributable to possession of the TEM (Type III a)beta-lactamase. As is common in other bacteria the gene specifying this enzyme is plasmid-borne in Haemophilus. Some ampicillin-resistant strains of H. influenzae can transfer the TEM beta-lactamase gene to other strains of Haemophilus, to Escherichia coli and to Pseudomonas aeruginosa. The features of such transfer are unusual and lead for example, to the induction of adenine requirement in recipient strains of P. aeruginosa. Crypticity measurements of beta-lactamase activity show that in comparison to P. aeruginosa or E. coli, the outer membrane of H. influenzae affords only a weak penetration barrier to beta-lactam antibiotics. This may have consequences for the stability and distribution of beta-lactamase production in Haemophilus spp. which are discussed. A comparison of the molecular properties of R-plasmids determining a variety of resistances and carried by strains of H. influenzae isolated in diverse geographical locations has revealed unexpected homologies. A series of such plasmids of similar molecular weights (about 30 X 10(6)) differ substantially only in the transposable resistance genes that they carry. A model based on these findings is presented to explain the acquisition of ampicillin- and other resistances by Haemophilus.
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PMID:beta-lactamases and R-plasmids of Haemophilus influenzae. 30 59


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