Phenotypic and Genotypic Detection of Aminoglycoside Resistant Klebsiella pneumoniae Isolated from Sputum Samples of Patients with Respiratory Tract Infections in Iraq

Abstract

A major source of respiratory tract infections, especially in hospitalized patients, the elderly, and people with weakened immune systems, Klebsiella pneumoniae is a clinically significant opportunistic pathogen. Antimicrobial resistance in K. pneumoniae is becoming more common, which is a major global health problem since it restricts treatment options and raises rates of morbidity and mortality. Since aminoglycoside antibiotics are commonly used to treat severe Gram-negative bacterial infections, resistance to these medicines is particularly significant among the several resistance mechanisms. Thus, the goal of the current investigation was to examine the genotypic and phenotypic traits of aminoglycoside-resistant K. pneumoniae that were isolated from sputum samples taken from patients suffering from respiratory tract infections. Standard microbiological techniques were used to process 40 sputum samples that were obtained from patients at Baqubah Teaching Hospital. Biochemical tests and the VITEK 2 automatic identification system was used to provide additional validation. In addition, polymerase chain reaction (PCR) targeting the rpoB gene was employed to ensure accurate molecular confirmation of the bacterial isolates. The antimicrobial susceptibility testing of Klebsiella pneumoniae isolates against aminoglycoside antibiotics revealed variable resistance patterns. The highest resistance rate was observed against streptomycin (72.7%), followed by neomycin (68.18%), while amikacin showed comparatively lower resistance (22.7%) . Genotypic analysis was subsequently performed using PCR to detect aminoglycoside resistance genes, with particular emphasis on the aph (3')-VI gene. The results revealed that 22 (55%) of the 40 sputum samples were identified as K. pneumoniae. Among these isolates, 10 (45.5%) exhibited resistance to aminoglycoside antibiotics and were selected for molecular investigation. PCR analysis demonstrated that all 10 aminoglycoside-resistant isolates (100%) carried the aph (3')-VI resistance gene, indicating a strong association between this gene and the observed aminoglycoside resistance phenotype. In conclusion, aminoglycoside-resistant K. pneumoniae represents a significant therapeutic and epidemiological challenge in respiratory tract infections. The integration of phenotypic identification methods with molecular diagnostic techniques provides a reliable approach for the accurate detection and surveillance of resistant strains. Continuous monitoring of resistance genes and antimicrobial susceptibility patterns is essential for guiding appropriate antibiotic therapy, improving patient outcomes, and strengthening infection control strategies in healthcare settings.