Biofilm Formation by Pathogens Causing Ventilator-Associated Pneumonia at Intensive Care Units in a Tertiary Care Hospital: An Armor for Refuge

Abstract

Background. Emerging threat of drug resistance among pathogens causing ventilator-associated pneumonia (VAP) has resulted in higher hospital costs, longer hospital stays, and increased hospital mortality. Biofilms in the endotracheal tube of ventilated patients act as protective shield from host immunity. They induce chronic and recurrent infections that defy common antibiotics. This study intended to determine the biofilm produced by pathogens causing VAP and their relation with drug resistance. Methods. Bronchoalveolar lavage and deep tracheal aspirates ( n = 70 ) were obtained from the patients mechanically ventilated for more than 48 hours in the intensive care units of Tribhuvan University Teaching Hospital, Kathmandu, and processed according to the protocol of the American Society for Microbiology (ASM). Antibiotic susceptibility testing was done following Clinical and Laboratory Standards Institute (CLSI) 2017 guidelines. Biofilm formation was determined using the microtiter plate method described by Christensen and modified by Stepanovoic et al. Results. Significant microbial growth was seen in 78.6% of the total samples with 52.7% monomicrobial, 45.5% polymicrobial, and 1.8% fungal infection. Among the 71 isolates obtained, bulk was gram-negative ( n = 64 , 90.1%). Pseudomonas aeruginosa (31.0%) was the predominant isolate followed by Acinetobacter calcoaceticus baumannii complex (16.9%), Klebsiella pneumoniae (16.9%), Citrobacter freundii (15.5%), Staphylococcus aureus (7.0%), Escherichia coli (5.6%), Citrobacter koseri (2.8%), Enterococcus faecalis (1.4%), Burkholderia cepacia complex (1.4%), and Candida albicans (1.4%). Of the total isolates, 56.3% were biofilm producers. Multidrug-resistant (MDR) organisms, extended-spectrum β-lactamase (ESBL), and metallo-β-lactamase (MBL) producers were preeminent among the biofilm producers. The highest producer of biofilm was P. aeruginosa (19.7%). Among gram-negative biofilm producers, 42.2% were MDR, 21.9% were ESBL producers, and 7.8% were MBL producers. Conclusion. Gram-negative nonfermenter bacteria account for the bulk of nosocomial pneumonia. MDR, ESBL, and MBL production was preponderant among the biofilm producers. The rampant spread of drug resistance among biofilm producers is summoning novel interventions to combat multidrug resistance.

Prevalence of Multidrug-Resistant Klebsiella pneumoniae Clinical Isolates in Nepal

“…pneumoniae (pooled prevalence, 64%). In various locations, the multidrug resistance was seen to vary from 6% to 91% [ 4 , 23 , 26 , 27 , 29 – 36 ].…”

Multi-drug resistant gram-negative bacterial pneumonia: etiology, risk factors, and drug resistance patterns

“…The matrix confers antibiotic resistance through processes such as slow penetration of antibiotics, expression of chromosomally encoded resistant genes or development of persistent cells, changes in bacterial growth rate and metabolic activities, altered microenvironment due to depletion of nutrients and/or accumulation of waste substances that will antagonize the action of antibiotics, and even counteracting the host immunity [ 99 ]. In mechanically ventilated patients, biofilms are associated with endotracheal intubation, which acts as a reservoir for drug-resistant pathogens causing VAP such as P. aeruginosa and A. baumannii that persist in the hospital settings [ 100 ].…”

Pseudomonas aeruginosa: Recent Advances in Vaccine Development

“…This prior colonisation increases the risk of developing ventilator-associated pneumonia by up to eight times [ 22 ], and is associated with substantial morbidity and mortality [ 25 ]. Mucoid biofilm formation permits P. aeruginosa to colonise medical equipment, including ventilators, catheters, and bronchoscopes [ 26 , 27 ]. Interestingly, a recent review outlined the burden of highly adapted biofilms within healthcare-associated plumbing devices [ 28 ].…”