Antimicrobial Susceptibility Pattern and In-vitro Biofilm Forming Abilities of Potential Pathogens Isolated from Inner Lumen of Endotracheal Tubes of Patients Admitted in Critical Care Units

Abstract

Introduction: The potential pathogens of ventilator associated pneumonia (VAP) have the ability to form biofilm within the endotracheal (ET) tube inserted in a patient. These pathogens can lead to onset of VAP once they are flushed into the lungs during mechanical ventilation. Methodology: A prospective study was conducted where ETtubes were collected from the patients in ICU after more than 48 hours of intubation. ET tube was cut into sections and inner lumen was scrapped. The material was inoculated on 5% sheep blood agar and MacConkey agar. The isolated pathogens were tested for identification and antibiotic susceptibility testing. Bacterial isolates were also tested for in-vitro biofilm formation in microtiter plate by 1% crystal violet assay. Results: Among the 100 ET tubes, 93 microorganisms were isolated which include 79 (84.9%) gram negative bacilli (GNB), 10 (10.8%) gram positive cocci (GPC), and 4 (4.3%) yeasts. Most common isolates were Acinetobacter species, Klebsiella species, Pseudomonas species, and E coli. Out of 10 GPC isolates, six were identified as Methicillin resistant strains including 4 (66.7%) coagulase negative Staphylococcus species and 2 (33.3%) S aureus. Out of 79 GNBs, 16 (20.3%) were extended spectrum beta lactomase (ESBL) producers, 14 (17.7%) AmpC, and 16 (20.3%) were carbapenemase producers. Carbapenemase production was further identified as metallo beta lactamase (MBL) producers (n=10) and serine carbapenemase producers (n=6). Out of 89 bacterial isolates, 82 (92.1%) were tested positive for in-vitro biofilm production while 07 (7.9%) were identified as non-adherent. Conclusion: Most of the ET tubes inserted for more than 48 hours inside a patient have a high risk of getting infested with potential biofilm producing pathogen. There is high rate of multi drug resistant (MDR) strains among these potential pathogens. The biofilm formed inside the ETtube possess the risk of onset of VAP.

Keywords

• Carbapenemase, Crystal violet assay, Multi-drug resistance, Nosocomial infections, Ventilator associated pneumonia.