Combined action of chloramphenicol and ampicillin on chloramphenicol-resistant Haemophilus influenzae

Chloramphenicol-resistant Haemophilus influenzae meningitis in young urban Nigerian children

In a developing country like Nigeria, the unusual emergence of Haemophilus influenzae type b, resistant to cost-effective antimicrobials, is of serious concern. We report three cases of H. influenzae type b meningitis in young Nigerian children in whom clinical and bacteriological features of resistance to chloramphenicol were identified. One of the cases had concomitant resistance to ampicillin (multiple-drug resistance). Significant anaemia was an associated feature in two cases, one of whom had a recent measles infection. All three cases were malnourished. The possible mechanisms of antimicrobial resistance in H. influenzae infections are highlighted while the need for periodic surveillance of antibiotic resistance profiles in resource-poor countries is emphasized. The potential value of prophylactic measures like H. influenzae type b conjugate immunization is discussed.

Randomised comparison of chloramphenicol, ampicillin, cefotaxime, and ceftriaxone for childhood bacterial meningitis. Finnish Study Group

In a multicentre study, 220 consecutive cases of bacterial meningitis in children older than 3 months were randomised to treatment with chloramphenicol, ampicillin (initially with chloramphenicol), cefotaxime, or ceftriaxone. The drugs were given in four equal daily doses for 7 days, except ceftriaxone which was given only once daily. 200 cases could be assessed; the causative organisms were Haemophilus influenzae type b (Hib) in 146; meningococci (Mnc) in 32; pneumococci (Pnc) in 13; and other or unknown in 9. In patients with Hib meningitis, sterilisation of the cerebrospinal fluid occurred most rapidly with ceftriaxone. Otherwise, in terms of overall clinical recovery, normalisation of laboratory indices, clinically significant adverse reactions, toxic effects, sequelae, and mortality rate, the treatment groups were very similar. However, there were 4 bacteriological failures, all in the chloramphenicol group. Also, the treatment was extended or changed in more cases in the chloramphenicol group than in the other groups. Chloramphenicol was thus inferior to the other three antimicrobials. Ampicillin is a good and cheap alternative, but there are difficulties with resistance. Easy administration tempts the use of ceftriaxone rather than cefotaxime but it causes diarrhoea. A 7-day course of ampicillin, cefotaxime, or ceftriaxone is sufficient in Hib, Mnc, or Pnc meningitis.

Chloramphenicol and tetracyclines

Tetracyclines have a broad range of clinical usefulness because of their broad antimicrobial spectrum of activity. For most routine gram positive and gram negative infections, alternative agents are available, but for Chlamydiae, Rickettsiae, Brucella, and Borrelia they still remain agents of choice. To some extent, gastrointestinal intolerance and inability to use these agents in patients with renal dysfunction have been overcome by the availability of doxycycline. Phototoxicity is a problem with this agent, however. Tetracycline is still useful as a sclerogenic agent for malignant effusions, and demeclocycline often is an agent of choice in therapy of inappropriate antidiuretic hormone secretion.

Susceptibility of relatively penicillin-resistant Streptococcus pneumoniae to newer cephalosporin antibiotics

Antimicrobial susceptibilities were performed at the Centers for Disease Control on 3400 Streptococcus pneumoniae isolates that were collected during a national survey of serotype-distribution of pneumococci found in normally sterile body fluids. The results showed 126 isolates (3.7%) to be relatively resistant to penicillin (RPR). The RPR strains were tested for susceptibility to cefuroxime, ceftriaxone, cefotaxime, cefamandole, cefaclor, ceftazidime, and moxalactam. These newer generation cephalosporin drugs were tested either because of their ability to penetrate into the cerebrospinal fluid (CSF) or for their activity against pneumococci. Three hundred ninety-one pneumococci were tested with 179 resistant to at least one antimicrobial. The RPR strains were not categorically resistant to the cephalosporins but were fourfold more resistant to them than were the penicillin-susceptible strains. The three most effective antimicrobials in the study for RPR were cefuroxime, cefotaxime, and ceftriaxone [corrected]. Each gave MICs that were attainable in CSF for RPR. Fifty percent of the RPR were inhibited by 0.06 mg/ml and 90% by 0.25 micrograms/ml of these antimicrobials. The least effective were cefaclor, moxalactam, and ceftazidime.