High levels of multiple antibiotic resistance among 938 Haemophilus influenzae type b meningitis isolates from Cuba (1990-2002).

Objectives: A national surveillance study to determine antimicrobial susceptibility in Haemophilus influenzae type b isolated from cerebrospinal fluid was carried out in Cuba from 1990 to 2002.

Methods: Susceptibility to ampicillin, co-amoxiclav, cefotaxime, ceftriaxone, co-trimoxazole, tetracycline, chloramphenicol and rifampicin was tested by the microdilution method according to the NCCLS guidelines.

Results: The 34 participating laboratories recovered 938 consecutive, non-identical isolates. All the isolates were retrieved from children aged <5 years. The mean number of isolates collected by year in the pre-vaccination era (1990-1998) was 93; after vaccination, 57 isolates were reported in 1999, 31 in 2000, four in 2001 and five in 2002. Resistance to ampicillin, co-trimoxazole, tetracycline and chloramphenicol was 46.3% (all beta-lactamase-positive), 51.3%, 33.2% and 44.0%, respectively. Ampicillin-resistant beta-lactamase-negative strains were not detected. All strains were susceptible to co-amoxiclav, cefotaxime, ceftriaxone and rifampicin. Ampicillin resistance was strongly associated with resistance to tetracycline, co-trimoxazole and chloramphenicol (P<0.001). Multidrug resistance was present in 43.8% of isolates. The most prevalent phenotype was resistance to ampicillin/chloramphenicol/tetracycline/co-trimoxazole, which was detected in 29.2% of strains overall. An increase in the prevalence of resistance to these antibiotics was observed from 1990 to 2000 in the range 40.7%-54.8% for ampicillin, 40.1%-51.6% for chloramphenicol, 45.4%-58.1% for co-trimoxazole and 23%-45.2% for tetracycline.

Conclusions: In Cuba, the widespread vaccination against Haemophilus influenzae type b prevented a large number of meningitis cases in children caused by strains resistant to multiple antibiotics.