Identification and Detection of Pathogenic Bacteria From Patients With Hospital Acquired Pneumonia in Southwest of Iran; Evaluation of Biofilm Production and Molecular Typing of Bacterial Isolates

Abstract

BackgroundHospital acquired pneumonia (HAP) HAP is the most second nosocomial infection and the most common infection in the intensive care unit. The aim of the present study was to determine the prevalence of pathogenic bacteria, their biofilm formation and molecular typing in sputum samples from patients with HAP in southwest of Iran.MethodsIn this cross-sectional study, 58 patients with HAP were included in this study. Clinical samples including sputum andendotracheal aspirate collected from each patient under aseptic conditions and were sent to the Microbiology Laboratory.Isolation and detection of bacteria were performed by culture and polymerase chain reaction methods.Biofilm formation was evaluated using by Congo red Agar or microtiter plate assay.A rep- PCR typing method was used for typing of gram-negative bacteria. MRSA isolates were typed using SCCmec typing method. Data were analyzed by SPSS software version 15 and chi-square test.ResultsUsing culture method, bacteria identified in 52 (89.7 %) of patients. Acinetobacter baumannii was the most prevalent (37%) organism and followed by Staphylococcus aureus, Pseudomonas aeruginosa and Escherichia coli. All of the A. baumannii and P. aeruginosa were biofilm producer. 12 cases (80%) of S. aureus isolates were MRSA and 91.6% of MRSA were SCCmec type III. The rep -PCR analysis showed 7 different patterns in 20 A. baumannii, 6 patterns in 13 P. aeruginosa and 4 patterns in 6 E. coli. Most of the A. baumanii isolates were multi drug resistant. ConclusionA. baumanii was more prevalent in VAP, while S. aureus as a major pathogen in N- VAP that maybe related to tendency of A. baumannii to the aquatic environment. Biofilm production ability in bacteria increased antibiotic resistance, development of chronic and persistent infection in HAP. Based on rep- PCR typing method we concluded that bacteria transmitted from patients or health care workers among different wards of hospital. Colistin can be used as a treatment in gram negative MDR isolates.