Serotype distribution and antibiotic susceptibility of Streptococcus pneumoniae strains in the South of Tunisia: a five- year study (2012-2016) of pediatric and adult populations

Abstract Objectives To analyze the serotype distribution of Streptococcus pneumoniae clinical isolates collected in the south of Tunisia over a 5-year period in different age groups and to assess their antimicrobial susceptibility patterns. Methods A total of 305 non-duplicate S . pneumoniae isolates were collected between January 2012 and December 2016 at the university hospital in Sfax, Tunisia. All isolates were serotyped by multiplex PCR. The antibiotic susceptibility of all isolates was determined using the disk diffusion test or Etest assay. Results Among the 305 pneumococcal isolates, 76 (24.9%) were invasive and 229 (75.1%) were non-invasive. The most common serotypes were 19F (20%), 14 (16.7%), 3 (9.2%), 23F (7.5%), 19A (5.9%), and 6B (5.9%). Potential immunization coverage rates for pneumococcal conjugate vaccines PCV7, PCV10, and PCV13 were 58%, 59.3%, and 78.7%, respectively. Three-quarters (75.3%) of pneumococcal isolates were non-susceptible to penicillin. The resistance rate to erythromycin was 71.4%. Only two isolates were resistant to levofloxacin. Conclusions 19F and 14 were the most prevalent serotypes in the south of Tunisia. The inclusion of a PCV in the immunization program could be useful for reducing the burden of pneumococcal diseases. The high resistance rate to penicillin and macrolides is alarming. Prudent use of antibiotics is crucial to prevent the selection of multidrug-resistant pneumococci.