Effect of Ampicillin and Chloramphenicol Against Haemophilus influenzae

The effects of combinations of ampicillin and chloramphenicol against seven strains of Haemophilus influenzae type b (five beta-lactamase-negative and two beta-lactamase-positive strains) were evaluated by killing-kinetic methods. Growth of strains was assessed in modified Levinthal broth against an inoculum of 1O5 organisms per ml; colony counts were performed immediately and at 6 and 20 h postinoculation. Ampicillin and chloramphenicol were completely bactericidal at 20 h, reducing bacterial densities to 0 colony-forming units per ml at concentrations equivalent to the ampicillin inhibitory concentration and twofold the chloramphenicol inhibitory concentration. Chloramphenicol at its inhibitory concentration or at one-half of its inhibitory concentration prevented the normally bactericidal activity of ampicillin at 20 h incubation, but not at 6 h.

mentioning

confidence: 99%

Chloramphenicol inhibition of the bactericidal effect of ampicillin against Haemophilus influenzae

Rocco¹,

Overturf²

1982

“…For the pneumococci, synergy was observed against 6 isolates, additive effects were observed against 14, and antagonism occurred against only 1 strain (Table 2).…”

Section: Resultsmentioning

confidence: 99%

“…Tests were done in microtiter plates by using a modification of a previously described procedure (6). Final concentrations of ampicillin increased in 0.01-pg/ml increments from 0.01 to 0.15 ,ug/ml.…”

Section: Methodsmentioning

confidence: 99%

“…This recommendation was supported by data from a recent in vitro study (6) which showed that ampicillin and chloramphenicol were not antagonistic against H. influenzae type b. However, limited information (1,(7)(8)(9)) is available about the interaction of these antibiotics against Streptococcus pneumoniae (pneumococcus) or Neisseria meningitidis (meningococcus), the-other two common causes of childhood meningitis.…”

mentioning

confidence: 98%

See 1 more Smart Citation

Effect of Ampicillin and Chloramphenicol Against Streptococcus pneumoniae and Neisseria meningitidis

Feldman

Zweighaft

1979

Self Cite

Antagonism, determined by isobolograms constructed from data from combinations of ampicillin and chloramphenicol at or below the minimal inhibitory or bactericidal concentrations, was observed against 13 clinical isolates of meningococcus and against one isolate of pneumococcus. Synergy occurred against six strains of pneumococcus and three of meningococcus. Additive effects were noted against 14 isolates of pneumococcus and 5 of meningococcus. There was no relationship between the minimal inhibitory or bactericidal concentrations for the isolates and the occurrence of antagonistic, additive, or synergistic effects. These data indicate that ampicillin and chloramphenicol may be antagonistic in vitro against some strains of pneumococcus or meningococcus.The combination of ampicillin or penicillin with chloramphenicol has been recommended as initial antibiotic therapy for patients with suspected bacterial meningitis because of the emergence of ampicillin-resistant Haemophilus influenzae type b strains (2). This recommendation was supported by data from a recent in vitro study (6) which showed that ampicillin and chloramphenicol were not antagonistic against H. influenzae type b. However, limited information (1, 7-9) is available about the interaction of these antibiotics against Streptococcus pneumoniae (pneumococcus) or Neisseria meningitidis (meningococcus), the-other two common causes of childhood meningitis.The present study was done to examine the in vitro effect of ampicillin and chloramphenicol against isolates of S. pneumoniae and N. meningitidis. MATERIALS AND METHODSBacterial isolates. A total of 21 strains of S. pneumoniae and 21 strains of N. meningitidis were isolated from patients or were obtained from Clyde Thornsberry (Center for Disease Control). The pneumococci were isolated from either blood (12 strains) or cerebrospinal fluid (9 strains). Capsular typing was not done on the pneumococcal strains. The meningococci were isolated from cerebrospinal fluid (13 strains), blood (2 strains), throat culture (2 strains), brain, spleen, or eye culture (1 strain each), and an unknown source (1 strain). Of the meningococci 13 strains were group B and 8 were group C.Media. Studies were done by using Mueller-Hinton broth to grow the meningococci and Todd-Hewitt broth supplemented with 5% human serum to grow the pneumococci. Bacterial colony counts of the meningococci or pneumococci were determined by plating 0.1-ml samples from serial 10-fold dilutions of broth cultures onto the surface of chocolate agar plates containing 1% IsoVitaleX (Baltimore Biological Laboratory) or plates containing 5% sheep blood, respectively (5).Studies of antimicrobial interaction. The 42 strains were tested in duplicate for their susceptibility to ampicillin and chloramphenicol, separately and in combination, by using a microtiter apparatus (Cooke Engineering Co., Alexandria, Va.).Tests were done in microtiter plates by using a modification of a previously described procedure (6). Final concentrations of ampicillin increased in 0.0...

“…Ampicillin and chloramphenicol have additive or even synergistic activity against many strains ofH. influenzae type b (12). However, it should be noted that for pneumococci this combination may be antagonistic, both in vitro and in experimental aniimals (13,31).…”

mentioning

confidence: 99%

Comparison of cotrimoxazole, ampicillin, and chloramphenicol in treatment of experimental Haemophilus influenzae type B meningitis

Perfect¹,

Lang²,

Durack³

1980

To evaluate cotrimoxazole in the treatment of bacterial meningitis, we compared its action with that of ampicillin and chloramphenicol in experimental Haemophilus influenzae type b meningitis. Both trimethoprim and sulfamethoxazole penetrated well into the cerebrospinal fluid of infected rabbits, reaching 40 and 26%, respectively, of their simultaneous serum levels. Levels measured 30 and 60 min after intravenous injection exceeded the minimum inhibitory concentration of this combination for H. influenzae by 10- to 100-fold. The mean ratio of trimethoprim to sulfamethoxazole in cerebrospinal fluid was 1:22. Cotrimoxazole was as effective as ampicillin in therapy of beta-lactamase-negative H. influenzae meningitis and as effective as chloramphenicol for a beta-lactamase positive strain. These findings corroborate favorable preliminary clinical experience reported by others and indicate that cotrimoxazole deserves further study in the therapy of bacterial meningitis.