Rising incidence of beta-lactam resistance among pneumococci in Kuwait: Failure of cefotaxime therapy in pneumococcal meningitis

ABSTRACT

Pneumococcal resistance to antimicrobial agents has become a global problem. This study was done to evaluate the resistance of Streptococcus pneumoniae [pneumococci] to penicillin G in Kuwait, and to assess the efficacy of other -lactam agents [cefotaxime or ceftriaxone] in the management of invasive pneumococcal infections. Surveillance studies were done in a general teaching hospital in Kuwait for penicillin G resistance [intermediate or high level resistance] of pneumococci isolated from clinical specimens by agar diffusion method using oxacillin [1 micro g] disc. In cases of pneumococcal meningitis, minimum inhibitory concentrations [MICs] of penicillin and cefotaxime were determined by agar dilution method, to differentiate intermediate resistance and high level resistance. An increase in the incidence of penicillin G-resistant pneumococci from 20.6% [94 out of 457 isolates] for the period 1985-1988 to 28.5% [40 out of 140 isolates] during 1992-1994 and 38.3% [43 out of 112 isolates] during 1995/96 was observed. During the period 1992-1994, 40-45% [7 out of 16 isolates] blood culture isolates of pneumococci were intermediate or highly resistant to penicillin. Therapy with cefotaxime or ceftriaxone produced a positive outcome in 6 of the 7 patients. However, failure of cefotaxime therapy to achieve a cure was noted in 1 patient who had systemic lupus erythematosus and intermediate resistant [penicillin MIC 0.5 mg/l; cefotaxime MIC 1 mg/l] pneumococcal septicaemia complicated with meningitis. A cure was however achieved with the addition of chloramphenicol to the regimen. Resistance of pneumococci to penicillin G and other -lactam agents is increasing in Kuwait. Penicillin-resistant pneumococcal bacteraemia in an immunosuppressed setting, if managed with cefotaxime or ceftriaxone, should be given high doses [cefotaxime 12 g/day or ceftriaxone 4 g/day] from the beginning. Cases of pneumococcal meningitis with cefotaxime-intermediate resistant strains [MIC 0.5-1 mg/l] on monotherapy consisting of cefotaxime or ceftriaxone should be viewed with caution. Chloramphenicol or vancomycin with rifampicin should be added to the regimen if therapeutic failure is suspected