Effect of inoculum size on Haemophilus influenzae type b susceptibility to new and conventional antibiotics

Laferrière, Céline; Marks, Melvin I.; Welch, David

doi:10.1128/aac.24.2.287

Cited by 14 publications

(2 citation statements)

References 13 publications

(13 reference statements)

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“…The demonstration of a significant inoculum effect for cefotaxime, ceftazidime and ceftriaxone was similar to the observations of Laferriere and co-workers (8). The demonstration of a significant inoculum effect for cefotaxime, ceftazidime and ceftriaxone was similar to the observations of Laferriere and co-workers (8).…”

Section: Methodssupporting

confidence: 86%

In vitro synergism of rifampin-cephalosporin combinations againstHaemophilus influenzae type b

Gordon

Wofford-McQueen

Shu

1990

Eur. J. Clin. Microbiol. Infect. Dis.

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The in vitro susceptibility of Haemophilus influenzae type b to rifampin, cefotaxime, ceftazidime, ceftriaxone and cefuroxime was examined at inocula of 10(5) and 10(7) CFU/ml. Time-kill curves were then obtained using antibiotic concentrations at one-half the MIC for each drug at the two inocula with combinations of rifampin plus each of the cephalosporins. There was a pronounced inoculum effect with all of the cephalosporins except for cefuroxime, but the MIC values were also higher for the latter drug. The rare failure of some cephalosporins to promptly sterilize the cerebrospinal fluid in meningitis should encourage investigation of the relationship between the inoculum effect, minimum bactericidal concentration and cerebrospinal fluid antibiotic levels in these clinical situations. A marked synergistic effect was noted for most of the isolates, and therefore, cephalosporin-rifampin combinations might show clinical utility.

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Section: Methodssupporting

confidence: 86%

In vitro synergism of rifampin-cephalosporin combinations againstHaemophilus influenzae type b

Gordon

Wofford-McQueen

Shu

1990

Eur. J. Clin. Microbiol. Infect. Dis.

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“…Haemophilus influenzae or Escherichia coli (20)(21)(22)25 Haemophilus influenzae appears to be less than Haemophilus influenzae allows easier access of ampicillin to its target, although many molecules are still hydrolysed by the beta.lactamase present in the periplasmic space (4,7,27), However, as with other beta-lactamase producing strains, an inoculum effect can be observed (28,29) which probably explains failure of treatment of infection with such strains. MICs of cephalosporins are generally not affected by the presence of the beta-lactamases, the most effective cephalosporins being the so called third-generation cephalosporins, cefotaxime in particular (30)(31)(32)(33)(34).…”

Section: Enzymatic Resistancementioning

confidence: 97%

Mechanisms of beta-lactam resistance inHaemophilus influenzae

Gutmann

Williamson

Collatz

et al. 1988

Eur. J. Clin. Microbiol. Infect. Dis.

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Haemophilus influenzae has become increasingly resistant to beta-lactam antibiotics. Three major mechanisms, both enzymatic and non-enzymatic, are involved. Enzymatic resistance is mainly due to production of a TEM-1 plasmid-mediated beta-lactamase, and in some cases to a new enzyme ROB-1. Of the non-enzymatic mechanisms, decreased permeability due to alteration of outer membrane proteins seems to be rare in comparison to decreased affinity of penicillin-binding proteins for beta-lactam antibiotics. Enzymatic resistance is present in about 10-20% of clinical isolates, while non-enzymatic resistance is present only in 2-4%.

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Ceftriaxone: A Beta‐lactamase—stable, Broad‐spectrum Cephalosporin with an Extended Half‐life

Beam

1985

Pharmacotherapy

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Ceftriaxone is an aminothiazolyl-oxyimino cephalosporin. It possesses the typical in vitro activity of a third-generation cephalosporin with excellent activity against many gram-negative aerobic bacilli: Escherichia coli; species of Proteus, Klebsiella, Morganella, Providencia and Citrobacter; and Enterobacter agglomerans. Ceftriaxone also has outstanding bactericidal action against pneumococci, group B streptococci, meningococci, gonococci and Hemophilus influenzae. In healthy volunteers, it has an exceptionally long serum half-life of 5.8-8.7 (mean 6.5) hours. It distributes well throughout all body spaces, including cerebrospinal fluid in the presence of inflammation. Dosage modification is necessary only when there is combined hepatic and renal dysfunction. Adverse reactions characteristic of cephalosporins have been observed with the administration of ceftriaxone. No unique toxicities have been identified, and hypoprothrombinemic bleeding is not part of the adverse reaction profile. Ceftriaxone has been used to treat serious bacterial infections in neonates, infants, children and adults. Bacteriologic and clinical success rates have consistently exceeded 90%. The drug has also been used as single-dose chemoprophylaxis in coronary artery bypass, biliary tract, vaginal hysterectomy and prostatic surgery. Efficacy and safety were similar to multiple-dose cefazolin. Ceftriaxone warrants special consideration because its extended half-life allows for less frequent dosing than other antimicrobials. Significant cost savings can be realized with proper use of this antibiotic.

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Effect of inoculum size on Haemophilus influenzae type b susceptibility to new and conventional antibiotics

Cited by 14 publications

References 13 publications

In vitro synergism of rifampin-cephalosporin combinations againstHaemophilus influenzae type b

In vitro synergism of rifampin-cephalosporin combinations againstHaemophilus influenzae type b

Mechanisms of beta-lactam resistance inHaemophilus influenzae

Ceftriaxone: A Beta‐lactamase—stable, Broad‐spectrum Cephalosporin with an Extended Half‐life

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