Phylogenetic analysis of Klebsiella pneumoniae isolates of respiratory tract infections in humans and sheep.

Abstract

Background: Klebsiella pneumoniae is an important opportunistic pathogen, which is capable of colonizing the respiratory system in both humans and animals causing mild to severe infections.

Aim: This study aims to isolate K. pneumoniae from the nasal discharges of human and sheep as well as identify the antibiotic resistance and molecular phylogeny of local isolates.

Methods: A total of 100; 50 humans and 50 sheep, positive nasal swab isolates were selected, and confirmed biochemically and by the VITEK-2 system. Molecular testing using the polymerase chain reaction (PCR) and phylogeny was conducted.

Results: On MacConkey agar, Klebsiella isolates appeared as large, pinkish, and mucoid colonies; while microscopically, it appeared as Gram-negative rods. Traditional biochemical tests revealed that 62% and 78% of human and sheep isolates were positive Klebsiella isolates, whereas respectively, 54.84% and 71.8% of these isolates were positive by VITEK-2. Antibiotic susceptibility tests showed that the human isolates were sensitive to aztreonam, piperacillin-tazobactam, ciprofloxacin, and cefuroxime. Subsequently, sheep isolates were sensitive to cefuroxime, ciprofloxacin, piperacillin-tazobactam, ampicillin, cefoxitin, and tetracycline. Targeting 16S rRNA gene, a total of 17 human and 28 sheep isolates were molecularly positive K. pneumoniae. Phylogenetic analysis of study human and sheep isolates showed their identity to NCBI Indian (LC747146.1) and Iraqi (LC711141.1) isolates, respectively. Comparative analysis between the local human and sheep isolates revealed a significant identity that ranged from 99.82% to 99.88% with a percentage of mutation ranging from 0.008% to 0.002%.

Conclusion: Klebsiella pneumoniae is a highly prevalent bacterium in both human and sheep with an observable resistance to antibiotics. Molecular phylogeny of study isolates demonstrated their close relation, suggesting the possible direct or indirect transmission of the bacterium from sheep to human or vice versa. Moreover, studies are greatly important to estimate the routes of bacterial transmission. Also, extensive hygiene practices could be lowered the spreading of K. pnuemoniae to farm workers.