Molecular serotyping and genotyping of penicillin non-susceptible pneumococci: the introduction of new sequence types, Tehran, Iran

Abstract

The emergence of penicillin non-susceptible Streptococcus pneumoniae (PNSP) isolates can pose significant challenges to today's health-care system. Resistant clonal isolates are disseminated in different regions and countries, and this study was focused on the description of the epidemiological spread of these strains. Clinical samples were collected from individuals admitted to hospitals affiliated to the Tehran University of Medical Sciences, Iran. To investigate the molecular characteristics of PNSP isolates, they were subjected to molecular typing using multi-locus sequence typing (MLST). Serotype distributions of S. pneumoniae isolates were also evaluated by multiplex PCR assay. The most prevalent serotypes in the PNSP isolates were 23F, 19F, 14, 3 and 9V. Two isolates were considered as a non-vaccine serotype. The MLST analysis showed that PNSP isolates belonged to five different clonal complexes (CC180, CC217, CC81, CC63 and CC320) and 42% (5/12) of the sequence types were novel (12936, 12937, 12938, 12939 and 12940). This study indicates the high level of heterogeneity that is present among PNSP isolates. Unexpected high genetic diversity in small populations indicates consecutive diversification of resistant strains.

Molecular characterization, antibiotic resistance pattern and capsular types of invasive Streptococcus pneumoniae isolated from clinical samples in Tehran, Iran

“…But, vaccination against the most common serotypes of S. pneumoniae using PCVs is not still included to the routine immunization program in the Iran and only recommended for high-risk groups [28]. The present study, in addition to others from Iran, shows that the PCV13 could cover the majority of the invasive pneumococcal isolates [19,20,28,29].…”

“…Habibi Ghahfarokhi et al observed that the common serotypes isolated from clinical samples were 23F, 14, 3, 19F and 19A [28]. In another study by Azarsa et al in Iran, the common serotypes isolated from clinical samples were 23F, 19F, 14, 3 and 9 V [29]. In Japan, Sakata et al evaluated 142 cases of IPD and observed that the most frequently serotypes were 6B, followed by 23F and 19F [30].…”

Changes in pneumococcal serotypes distribution and penicillin resistance in healthy children five years after generalization of PCV10

“…In our study, we revealed that the rates of PNSP were 100%, 44%, 25%, and 25% for serotypes 6B, 6C/6D, 14, and 19B/19C, respectively. Notably, in China, PNSP was commonly detected among serotypes 23F (81.4%), 19F (70.7%), 19A (97.6%), 14 (77.8%), and 6A (66.7%) isolated from invasive infections [ 41 ]. The persistence of PNSP in healthy carriers following the introduction of PCV10 is likely associated with high usage of antibiotics, which may exert significant pressure driving S. pneumoniae strains to acquire antibiotic resistance [ 42 ].…”