Serotype Distribution, Antibiotic Susceptibility and Family Typing of Pneumococcal Surface Protein A (PspA) among Iranian Streptococcus pneumoniae Isolates

Background and Aim : Streptococcus pneumoniae is a major cause of morbidity and mortality worldwide and an etiological agent causing various infectious diseases ranging from non-invasive to invasive diseases. The high prevalence of multidrug-resistant pneumococci has become a global concern. Available vaccines are serotype dependent and protect against only a limited number of pneumococcal serotypes. One of the virulence factors of pneumococci is pneumococcal surface protein A (PspA). This protein is highly conserved and an attractive candidate antigen for the development of new effective vaccines. PspA is classified into ۳ families and ۶ clades based on its structure. The distribution of pneumococcal serotypes among the different PspA families and clades varies from country to country. The purpose of this study is to investigate of the serotype distribution, antibiotic susceptibility, and the diversity of PspA family types from pneumococcal isolates from nasopharyngeal swab samples of children under ۶ years of age, referred to medical centers in Tehran.Methods : A total of ۱۰۰ S. pneumoniae isolates from nasopharyngeal swab samples were characterized for PspA family typing, antibiotic resistance, and capsular typing. The antibiotic susceptibility test was performed based on the Clinical and Laboratory Antimicrobial Standards Institute (CLSI). Pneumococcal serotyping was performed using multiplex polymerase chain reaction methods, and PspA family typing was also done using PCR with specific primers for family typing.Results : Our results showed that serotype ۶A/۶B is the most prevalent in all isolated pneumococcal strains. All strains were sensitive to Levofloxacin, while ۸۸.۶۴% were resistant to gentamycin. Our studies also demonstrated that all of these strains were positive for the presence of the cpsA and pspA genes. This study also indicated that the majority and minority of the isolates belonged to PspA family ۲ and PspA family ۳, respectively. Also, ۲۳.۳۷% of the strains were placed in both PspA families ۱ and ۲.Conclusion : This study, along with other studies, demonstrated the presence of the pspA gene in all strains. Since most isolates were classified as PspA family ۲, PspA family ۲ can be attractive candidate antigens for the development of novel, effective protein-based pneumococcal vaccines.

کلیدواژه ها:

Streptococcus pneumoniae ، Antibiotic Susceptibility ، Pneumococcal Surface Protein A ، Genetic Diversity ، Iran