Study of microbiological isolates and antibiotic susceptibility patterns in suspected cases of ventilator-associated pneumonia with bronchoscopy-based surveillance technique in ICU

Ventilator-associated pneumonia (VAP) is a hospital-acquired lung infection that occurs in patients, who are mechanically ventilated for at least 48 hours, either through tracheostomy or endotracheal intubation.1,2 It is divided into early (within 4 days after mechanical ventilation) and late (from the fifth day onwards).2 This disease is the second most common nosocomial infection in intensive care unit patients.3,4 The microbial causes of ventilator-associated pneumonia vary considerably by geographic location and over time. The most common pathogens involved in ventilator-associated pneumonia are bacteria including E.coli, Klebsiella(gram-negative bacilli) and Staphylococcus aureus (gram-positive coccus). There are variousother causative organisms like Pseudomonas species and Acinetobacter species that are resistant to different antibiotics and are referred to as multidrug-resistant (MDR) species4,5 As per standardized international terminology created by European Centre for Disease Control (ECDC) and Centre for Disease Control & Prevention (CDC), Atlanta, the multidrug-resistant (MDR) and extensively drug-resistant (XDR) have been well defined. The term MDR or multidrug-resistant bacteria denotes those bacteria that have acquired resistance to one or more agents within three or more antimicrobial categories. Extensively drug-resistant (XDR)bacteria denote those that have acquired resistance to at least one antimicrobial agent in all but two antimicrobial categories. VAP is suspected in patients with clinical signs of infection, such as at least two of the following criteria: new onset of fever, purulent endotracheal secretions, leucocytosis or leukopenia, increase in minute ventilation, decline in oxygenation and/or increased need for vasopressors to maintain blood pressure.The risk factors associated with ventilator-associated pneumonia include the duration of mechanical ventilation, underlying lung disease, infection, acute respiratory distress syndrome, neurological disorder, trauma, prior antibiotic usage and red cell transfusion6. VAP is believed to occur in 8% to 28% of mechanically ventilated patients.2,7 The incidence of VAPattributable mortality is difficult to quantify due to the possible confounding effect of associated conditions, but VAP is thought to increase the mortality of the underlying disease by about 30%.8 VAP is also associated with considerable morbidity, including prolonged ICU length of stay, prolonged mechanical ventilation and increased costs of hospitalization. Flexible fibre-optic bronchoscopy is a routinely used invasive diagnostic procedure employed for the diagnosis of various pulmonary diseases and aids in their adequate management. In patients with ventilator-associated pneumonia, bronchoscopy has a diagnostic as well as 2therapeutic role. This includes aspiration of retained secretions & mucous plugs, administration of drugs and bronchoalveolar lavage. One major technical problem with all bronchoscopic techniques is the proper selection of the sampling area in the tracheobronchial tree. Usually, the sampling area is selected based on the location of the infiltrate on the chest radiograph or the segment visualized during bronchoscopy having purulent secretions9. In case of doubt and because autopsy studies indicate that ventilator-associated pneumonia frequently involves the posterior portion of the right lower lobe, this area should probably be sampled on priority.10The risk inherent in bronchoscopy appears slight even in critically ill patients requiring mechanical ventilation, although the associated occurrence of cardiac arrhythmias, hypoxemia, or bronchospasm is not unusual.Microbiological analysis samples from the lower respiratory tract can be obtained by bronchoalveolar lavage, protected-specimen brush and direct lung aspirates. Among these techniques, bronchoalveolar lavage provides the most accurate representation of the bacterial burden in the lungs.11 Bronchoalveolar lavage (BAL) has been shown to be reliable for the identification of microorganisms present in the lung specimens of patients with bacterial pneumonia.12,13Bronchoalveolar lavage (