Detection of blaVIM-M and blBbKPC genes in Streptococcus pneumoniae isolated from sputum samples in Iraqi patients

Abstract

Streptococcus pneumoniae (pneumococcus) is one of the leading causes of community-acquired pneumonia, as well as a major cause of morbidity and mortality around the globe. Of these carbapenemase genes, blaVIM and blaKPC are of great clinical significance and have been frequently described in various Gram-negative pathogens, whereas little work has been done on pneumococcal isolates. The aim of the present study was to detect the presence of blaVIM and blaKPC genes in S. pneumoniae isolated from sputum samples of Iraqi patients suffering pneumonia and confirm the association of these genes with antimicrobial resistance patterns. This cross-sectional study was conducted in Al-Sadr Medical City Hospital, Najaf, Iraq, extending from June 2024 to January 2025. We included 96 patients with clinical diagnosis of pneumonia. Sputum specimens were collected in sterile containers and then cultured according to standard microbiological procedures. Identification of S. pneumoniae was based on the basis of colony morphology, gram staining and biochemical tests. The antimicrobial susceptibility testing against ceftriaxone, ciprofloxacin, gentamicin, imipenem, and meropenem was performed by the Kirby–Bauer disc diffusion method following the Clinical and Laboratory Standards Institute (CLSI) guidelines. Conventional polymerase chain reaction (PCR) was used for the molecular detection of blaVIM and blaKPC genes. Antimicrobial resistance rates to the tested antibiotics were variable, but they were highest for gentamicin and ciprofloxacin, and the carbapenems retained relatively higher activity. Molecular analysis indicated that blaVIM and blaKPC genes were found in 11.5% and 7.3% of the isolates, respectively. The presence of both genes was significantly associated with resistance to imipenem and meropenem (p<0.001). On the other hand, the non-β-lactam resistance showed no significant correlation with the carbapenemase gene carriage. These findings highlight the need for ongoing molecular surveillance, rational use of antibiotics and improved infection control measures to contain the spread of carbapenem resistance from one respiratory pathogen to another