Predominance of ST320 among Streptococcus pneumoniae serotype 19A isolates from 10 Asian countries

Abstract

Although diverse clones were identified among 19A S. pneumoniae isolates, MDR ST320 was the predominant clone in Asian countries. Its predominance, even in countries with no or low coverage of PCV7, may indicate that its emergence and dissemination was due to more than just vaccine selection pressure in Asian countries. A longitudinal investigation of the change of serotypes and genotypes since the introduction of PCV7 is required to understand the emergence and dissemination mechanisms of a certain clone of 19A S. pneumoniae isolates.

Serotype and Clonal Evolution of Penicillin-Nonsusceptible Invasive Streptococcus pneumoniae in the 7-Valent Pneumococcal Conjugate Vaccine Era in Italy

“…Both these clones have expanded successfully in different areas of the globe. Taiwan 19F -14/ST236/CC320 spread rapidly in Asian countries before PCV7 introduction (4,21); in the United States it has been associated with the emergence of MDR serotype 19A isolates after PCV7 implementation (2). Colombia 23F -26/ST338/CC156 has been increasingly found in the United States and Japan (13,17).…”

Changes in Streptococcus pneumoniae Serotype 19A Invasive Infections in Children from 1993 to 2011

“…Serotype 19A, which is not included in the seven-valent pneumococcal conjugate vaccine (PCV7), emerged as the most prevalent serotype in several studies from the United States and was associated with multidrug resistance (1)(2)(3)(4). Pediatric invasive pneumococcal disease (IPD) caused by serotype 19A has been reported in European and Asian countries (5)(6)(7). Serotype 19A has a propensity to cause mastoiditis (2), and mastoiditis caused by serotype 19A infections was more likely to require intraoperative mastoidectomy than mastoiditis caused by non-19A infections (8).…”

Predominance of Serogroup 19 CC320/271 among Penicillin-Nonsusceptible <i>Streptococcus pneumoniae</i> Isolates after Introduction of the PCV7 Vaccine in Several Regions of Japan

“…Nonvaccine serotype 19A, which became predominant globally after the introduction of PCV7, was still a minor serotype between 2010 and 2014 on the basis of our data. In addition, the major ST was ST236 (which is regarded as the source strain) and not ST320, which had been predominant among serotype 19A isolates in Asian countries (11). A recent report out of Hong Kong describes the clonal expansion of serotype 19F ST271 (which has high resistance to β -lactams and is a single-locus variant of ST236) after the introduction of PCV7 (20).…”

“…Most serotype 19A S. pneumoniae isolates belonged to clonal complex 320 (CC320), which originated from the multidrug resistant (MDR) Taiwan19F-14 Pneumococcal Molecular Epidemiology Network clone (a double-locus variant of , in many parts of the world (9,10). According to the ANSORP study, MDR sequence type 320 (ST320) was the most prevalent clone among 19A S. pneumoniae isolates from Asian countries (11). In the United States, the emergence of MDR CC320 has contributed to an increase in serotype 19A prevalence after the introduction of PCV7 (5).…”