Drug-resistant Streptococcus pneumoniae in the Lebanon: implications for presumptive therapy

A total of 50 consecutive clinical isolates of Streptococcus pneumoniae, co llected between 1996 and 1998, were tested against six antimicrobial agents using the E-test. The percentages of fully resistant (R) and intermediatel y-R strains, respectively, were: benzyl penicillin 18 and 38%, amoxycillin- clavulanate 6 and 12%, cefuroxime 22 and 16%, ceftriaxone 2 and 16%, and cl arithromycin 10%. Fully and or intermediately multidrug-resistance (two or more drugs) was seen in 44% of the isolates, 18% being fully resistant. The MIC breakpoint for cefaclor is not defined by the National Committee for C linical Laboratory Standards (NCCLS) but MICs showed that: 76% of the isola tes had an MIC of less than or equal to 8 mg/l, 4% had an MIC of 16 mg/l an d 20% had an MIC of greater than or equal to 32 mg/l. There was agreement b etween the E-test Pen MIC results and the 1 mu g oxacillin (oxa) disk diffu sion screen test for the 22 susceptible and the nine fully R strains but no t for the 19 strains with Pen MICs between 0.1 and 1 mg/l; this shows the i mportance of MIC determination in such isolates. Penicillin and multiply an tibiotic-resistant pneumococci are spreading in Lebanon, emphasizing the ne cessity to reconsider current treatment regimens in this country. (C) 1999 Elsevier Science B.V. and International Society of Chemotherapy. All rights reserved.