Antimicrobial susceptibility, serotype distribution, virulence profile and molecular typing of piliated clinical isolates of pneumococci from east coast, Peninsular Malaysia

Nurul Diana Dzaraly,Nurshahira Sulaiman,Fatimah Haslina Abdullah,Farahiyah Mohd Rani,Mohd Nasir Mohd Desa,Abdulrahman Muthanna,Nor Iza A Rahman,Niazlin Mohd Taib,Nurul Hana Zainal Baharin,Cheah Yun Shuan,Navindra Kumari Palanisamy,Zarina Ariffin,Siti Norbaya Masri,Tuan Suhaila Tuan Soh,Zarizal Suhaili

doi:10.1038/s41598-021-87428-z

Abstract

Pilus has been recently associated with pneumococcal pathogenesis in humans. The information regarding piliated isolates in Malaysia is scarce, especially in the less developed states on the east coast of Peninsular Malaysia. Therefore, we studied the characteristics of pneumococci, including the piliated isolates, in relation to antimicrobial susceptibility, serotypes, and genotypes at a major tertiary hospital on the east coast of Peninsular Malaysia. A total of 100 clinical isolates collected between September 2017 and December 2019 were subjected to serotyping, antimicrobial susceptibility test, and detection of pneumococcal virulence and pilus genes. Multilocus sequence typing (MLST) and phylogenetic analysis were performed only for piliated strains. The most frequent serotypes were 14 (17%), 6A/B (16%), 23F (12%), 19A (11%), and 19F (11%). The majority of isolates were resistant to erythromycin (42%), tetracycline (37%), and trimethoprim-sulfamethoxazole (24%). Piliated isolates occurred in a proportion of 19%; 47.3% of them were multidrug-resistant (MDR) and a majority had serotype 19F. This study showed ST236 was the most predominant sequence type (ST) among piliated isolates, which was related to PMEN clone Taiwan19F-14 (CC271). In the phylogenetic analysis, the piliated isolates were grouped into three major clades supported with 100% bootstrap values. Most piliated isolates belonged to internationally disseminated clones of S. pneumoniae, but pneumococcal conjugate vaccines (PCVs) have the potential to control them.

Highlights

Pilus has been recently associated with pneumococcal pathogenesis in humans
A total of 100 S. pneumoniae isolates were collected over a period of 28 months, between September 2017 and December 2019
We found that the pneumococcal pilus islet was associated with clonal spread involving many serotypes such as 19F, 19A, and 6A/B, which are mostly covered by pneumococcal conjugate vaccines (PCVs)

Summary

Introduction

Pilus has been recently associated with pneumococcal pathogenesis in humans. The information regarding piliated isolates in Malaysia is scarce, especially in the less developed states on the east coast of Peninsular Malaysia. We studied the characteristics of pneumococci, including the piliated isolates, in relation to antimicrobial susceptibility, serotypes, and genotypes at a major tertiary hospital on the east coast of Peninsular Malaysia. The 7-valent pneumococcal conjugate vaccine (PCV7) was first implemented for children in the United States of America (USA) in 2000 and Europe in 2001 to reduce the burden of pneumococcal diseases This vaccine covers serotypes 4, 6B, 9V, 14, 18C, 19F, and 23F. The role of pili is to enhance the ability of pneumococci to adhere to epithelial cells; at the same time, the piliated strain was found to be significantly more virulent in a murine model of invasive diseases[8] This suggests that pneumococcal pili provide an extra advantage to initiate colonization, leading to the downstream of infection and pathogenesis process[9,10,11]. Two pili islets have been detected in pneumococci, namely, PI-18 and PI-29

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Results

Discussion

Conclusion