Bacteriological Profile of Bacteria Species Isolated from Sputum Samples in Respiratory Tract Infections Patients and their Association with Antimicrobial Resistance Pattern

Abstract

Background: Respiratory tract infections (RTIs) are among the most common infectious diseases, and identifying their bacterial causes is essential for appropriate treatment and antimicrobial resistance surveillance. This study aimed to determine the frequency of bacterial growth in sputum samples and identify the predominant bacterial pathogens associated with RTIs in patients attending Azadi Hospital, Kirkuk Province, Iraq. Methods: A total of 77 sputum samples were collected from patients at Azadi Hospital between July 1, 2025, and February 1, 2026. Samples were cultured using standard bacteriological media. Bacterial isolates were identified based on cultural characteristics, microscopic examination, biochemical tests, and the VITEK automated identification system. Antimicrobial susceptibility testing was also performed. Results: Bacterial growth was detected in 18 samples (23.38%), whereas 59 samples (76.62%) showed no bacterial growth. Most samples were obtained from females and patients aged over 50 years. Gram-positive and Gram-negative bacteria represented 55.56% each of the isolates. Streptococcus pneumoniae and Staphylococcus aureus were the most frequently isolated species (22.22% each), followed by Acinetobacter baumannii (16.66%) and Klebsiella pneumoniae (11.11%). Conclusion: The low culture-positive rate indicates that sputum culture alone may have limited diagnostic yield for bacterial RTIs. Increasing the number and quality of respiratory specimens and combining culture with appropriate diagnostic approaches may improve pathogen detection and provide more reliable information for antimicrobial resistance surveillance.