Colistin resistance in organisms causing ventilator-associated pneumonia – Are we going into pre-antibiotic era?
Introduction: Ventilator-associated pneumonia (VAP) is one of the most common infections in mechanically ventilated patients. VAP is usually caused by multidrug resistant bacteria. The beta-lactam antibiotics, which were once considered the backbone of antibiotic therapy is under strain due to a variety of bacterial antibiotic resistance. Recent evidence suggests that colistin is the only cannon left in the medical armory to treat bacterial infections, mainly those acquired in the hospital that no other drug can treat. But excessive use of colistin has recently led to resistance to these group of drugs. Initially, resistance to colistin was due to mutations but recently detected plasmid-mediated colistin resistance, which is transferrable, heralds the breach of the last group of antibiotics, polymixins. Colistin resistance is on the rise, especially in South East Asia countries. So strict infection control policies are required to control the spread of this infection.
Objective: This study was conducted to see the burden of colistin resistant organisms causing VAP in ICU of Himalayan Institute of Medical Sciences, Dehradun, India.
Design: A prospective observational study.
Setting: Study was conducted in a 40-bed semi-closed ICU of a tertiary care super specialized hospital between August 2016 to April 2017.
Patients and participants: Out of 2304 patients admitted to ICU 420 had a suspicion of VAP. A total of 476 lower respiratory tract samples were collected from 400 patients with clinical evidence of lower respiratory tract infections in form of endotracheal (ET) aspirate, tracheal tube (TT) aspirate, and bronchoalveolar lavage (BAL) specimens.
Intervention: Organism identification and the susceptibility testing were done by using an automated system VITEK 2.
Result: Out of 476 sample received, only 186 samples organisms were isolated, which showed Acinetobacter baumanii was the most common organism. It was found that 19 organisms had resistance to colistin. Klebsiella pneumoniae (25.7%) was the most common organism, which was resistant to colistin, followed by Pseudomonas aeruginosa (16%) and Acinetobacter baumanii (2.4%).
Conclusion: The emergence of colistin resistant strains is a very serious problem as there are only few treatment options. As colistin use is a risk factor for colistin resistance, colistin should not be used alone, combination therapy should be preferred.