ABSTRACT
The major difficulty facing microbial investigation in ventilator associated pneumonia [VAP] is to find a method of choice for distal airway sampling avoiding the contamination of upper respiratory colonizers. Since the inappropriate antibiotic treatment is associated with increased morbidity and mortality therefore the detection of the pathogen causing VAP remains the cornerstone in management. This study was conducted to evaluate the role of bronchoscopic bronchoalveolar lavage [BAL] in the etiologic diagnosis of VAP in Pediatric Intensive Care Unit of Ain Shams University Hospital. In addition, aimed to analyze the pulmonary and systemic inflammatory responses, reflected by levels of serum and BAL interleukin 6 [lL-6] and IL-8, and their association with morbidity and mortality. Thirty VAP patients and 10 mechanically ventilated patients without development of VAP [control group] were enrolled in the study. Endotracheal aspirate [ETA], BAL, and blood samples were collected from VAP patients for microbiological diagnosis. ETA and BAL samples were cultured quantitatively and the isolated organisms were identified by standard techniques. Antimicrobial susceptibility testing was done by disc diffusion method. Blood samples were collected from patients and controls for estimation of serum levels of IL-6 and IL-8. Also levels of these cytokines were estimated in BAL of VAP patients. Twenty four [80%] BAL cultures and 14 [46.7%] ETA cultures were considered positive [thresholds of >/= 10[4] and >/= 10[6] CFU/mL]. Blood cultures were positive in 8 [26.7%] patients. The concordance between BAL and ETA culture results was 66.7% with fair agreement [K= 0.359] while it was only 46.7% between blood and BAL culture results with poor agreement [K= 0.167]. Staphylococcus aureus isolates were recovered from patients with early-onset VAP. Pseudomonas aeruginosa and enteric Gram negative bacilli were the isolated pathogens in late-onset VAP and showed a wide range of antibiotic resistance. The rate of positive BAL culture was significantly higher in late-onset VAP patients [P<0.050]. Serum levels [ng/mL] of lL-6 and IL-8 were significantly higher in VAP patients than controls. VAP patients with sepsis had higher levels of serum and BAL IL-8 and IL-6 than VAP patients without sepsis [p < 0.0001]. BAL IL-6 had the greatest ability to discriminate between patients with and without lung injury. Serum and BAL lL-6 and IL-8 showed a statistically significant [P<0.001] increase in non-survivors among VAP patients and serum IL-8 had the greatest discriminating ability between survivors and non-survivors. Quantitative culture of BAL samples had the potential to be a useful tool for the etiological diagnosis of VAP among mechanically ventilated pediatric patients. However, lowering of the diagnostic threshold to discriminate infection from colonization in patients with prior antibiotic therapy has to be considered. BAL and serum levels of IL-8 and IL-6 might be promising markers for morbidity and poor prognosis in mechanically ventilated pediatric patients