Bacterial profile and their antimicrobial resistance patterns among patients with community-acquired pneumonia in southwestern Iran.

Background and objectives: Community-acquired pneumonia (CAP) is one of the most common life-threatening infections, occurring in the community or within the first 48 hours of a patient's hospitalization. The present study aimed to investigate the frequency of pathogenic bacteria and their antibiotic resistance pattern in the sputum of patients with community-acquired pneumonia in Yasuj from 2018 to 2019.

Materials and methods: In the present study, 128 patients with CAP were included. Under aseptic conditions clinical samples including sputum collected from each patient were sent to the Microbiology Laboratory. Specific culture media and biochemical tests were used to identify the bacteria. Antimicrobial resistance patterns of the isolates were examined by disc diffusion. DNA was extracted from sputum using the phenol-chloroform method. The PCR method was used for the molecular detection of bacteria. Data were analyzed using SPSS software version 22 and the chi-square test.

Results: The most common clinical symptoms in patients were sputum (68.8%), fever (64.1%), shortness of breath (60.2%), cough (50.8%), and chest pain (24.2%). A total of 133 bacteria were identified by culture and 117 bacteria by PCR. In the current study, the most prevalent organisms were Streptococcus pneumoniae (24.1%), Hemophilus influenzae (18%), Staphylococcus aureus (13.5%), and Moraxella catarrhalis (11.4%). Antibiogram test showed that most of the Gram-negative bacteria were resistant to levofloxacin (22.6%), rifampin (20.8%) and ceftriaxone (17%), and the highest resistance rate to clindamycin (43.1%), ciprofloxacin (43.1%) and amoxicillin (41.4%) were detected in the Gram-positive bacteria. Cefepime was the most effective antibiotic against Gram negative bacteria.

Conclusion: S. pneumoniae was the most prevalent bacteria identified by culture and PCR methods in patients with CAP, indicating an important role of this bacterium in the pathogenesis of CAP. According to the results, cefepime can be used to treat patients with CAP with Gram-negative bacteria. In the present study, S. pneumoniae, S. aureus, P. aeruginosa, H. influenzae, M. catarrhalis, and K. pneumoniae have been isolated from the CAP patient population with varying frequencies. This is consistent with various studies in different parts of the world.