title: Beta-lactam and macrolide resistance and serotype distribution among Streptococcus pneumoniae isolates from Saudi Arabia.
abstract: Three hundred thirty-six clinically significant Streptococcus pneumoniae isolates were collected from laboratories of different hospitals in Riyadh, Saudi Arabia. Most of these isolates were from pulmonary and otitis media (68.2%), and 31.8% were extrapulmonary (blood and CSF). Of the 336 isolates, 44.6% were susceptible to penicillin, and 55.4% were penicillin non-susceptible (35.7% were intermediate and 19.7% were fully resistant). The isolates showed 9.0% resistance to co-amoxiclav, 31.8% to cefuroxime and 39.4% to cefprozil. None of the isolates were resistant to ceftriaxone. Overall macrolide resistance rates were 22.6% to erythromycin, 18.5% to roxithromycin, 17.9% to azithromycin and 17.3% to clarithromycin. Most penicillin non-susceptible pneumococci were of serogroups/types 19 (21.0%), 6 (10.8%), 18 (8.6%), 23 (8.1%) and 14 (7.0%). Serogroups 9, 15, and 1 were found in 5.4%, 4.3%, and 2.2% of the isolates, respectively. Nontypeable strains constituted 6.5%. In exploring the mechanism of resistance to macrolides, 28 of 76 (36.8%) of isolates were erythromycin-resistant due to ribosomal mechanism (all were constitutive type, none were inducible), whereas 48 (63.2%) isolates were resistant due to an efflux mechanism. Good antibiotic control with periodical antibiotic surveillance and appropriate use of pneumococcal vaccine may improve current treatment of pneumococcal infections.
authors.affiliation: Division of Microbiology, Pharmaceutics Department, College of Pharmacy, King Saud University, Riyadh, Saudi Arabia.
authors.forename: S I
authors.initials: SI
authors.lastname: Fouda
authors.forename: A A
authors.initials: AA
authors.lastname: Kadry
authors.forename: A M
authors.initials: AM
authors.lastname: Shibl
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D006801:Humans; D015994:Incidence; D018942:Macrolides / Q000494:pharmacology*; D008826:Microbial Sensitivity Tests; D010033:Otitis Media / Q000382:microbiology; D011018:Pneumonia, Pneumococcal / Q000382:microbiology; D012270:Ribosomes; D012529:Saudi Arabia / Q000453:epidemiology; D012703:Serotyping; D013290:Streptococcal Infections / Q000188:drug therapy* / Q000453:epidemiology; D013296:Streptococcus pneumoniae / Q000145:classification / Q000187:drug effects* / Q000472:pathogenicity*; D018440:beta-Lactam Resistance
chemical_list: D000900:Anti-Bacterial Agents; D018942:Macrolides