Analysis of Autolysin-Encoding Gene (lytA) Sequencing of Streptococcus pneumoniae Isolated from Iraqi Patients with Bacterial Meningitis

Zainib Hatif Abbas, Rajaa Abed Ali, Rafal J. Obaid, Hind Taher Muhi and Kais Kassim Ghaima

Abstract

Streptococcus pneumoniae is an important human pathogen associated with a variety of diseases, from mild infections to invasive pneumococcal disease and meningitis. Autolysin (N-acetylmurayl-L-alanine amidase) (LytA) is its most important virulence factor, regulating autolysis, promoting inflammatory processes and biofilm formation, and inhibiting bacterial clearance. In this research we tried to study the lytA gene enclosed autolysin in S. pneumoniae isolates that were detected in Iraqi patients suffering from bacterial meningitis. One hundred CSF samples were collected, and viable bacterial isolates were identified using classical and molecular microbiological methods. All isolates underwent an antibiotic susceptibility test. Out of 100 samples the result showed that 32 isolate of S. pneumoniae was identified by VITEK2 system. The majority of isolates exhibited high resistance to ciprofloxacin and chloramphenicol while higher sensitivity was recorded for Vancomycin and Ceftazidime. All the isolates were also positive for specific genes (lytA and ply) of S. pneumoniae using PCR amplification. Sanger sequencing of the lytA gene indicated that all strains showed high homology with reference strains and no significant mutations were detected (a sign of genetic stability). The autolysin enzyme also possesses conserved domains suggesting the likely functional significance of autolysin in virulence and pathogenesis, notably in meningitis. These findings underscore the potential of lytA and ply as diagnostic biomarkers and therapeutic targets. The study reveals important epidemiological relevance of S. pneumoniae in Iraqi hospitals and confirms the previously described global data on conservation of virulence determinants at the molecular level.