[Value of optimization of bedside Gram staining of sputum smear in the early diagnosis and treatment of ventilator-associated pneumonia].

OBJECTIVE: To investigate the significance of optimization of bedside Gram staining of sputum smear in the early diagnosis and antimicrobial treatment for ventilator-associated pneumonia (VAP) patients.

METHODS: The data of patients with VAP undergoing mechanical ventilation over 48 hours in the Department of Critical Care Medicine of Tianjin Fourth Central Hospital from June 2009 to June 2014 were analyzed. The patients were divided into two groups according to whether or not bedside Gram staining of sputum smear was used or not. The sputum samples from lower respiratory tract of all VAP patients were collected daily with tracheal catheter. In empirical examination group (from June 2009 to December 2011, n=43), the patients received antibiotics at the time of onset of VAP, selection of antibiotics depended on the information of bacterial epidemiology of the intensive care unit (ICU), and also existence of high risk factors of multi-drug resistant bacteria. In target treatment group (from January 2012 to June 2014, n=43), the patients received antibiotics according to the results of bedside instant sputum smear examination and empirical antibiotic regime. The correlation between the results of sputum smear examination and culture result was analyzed. The levels of body temperature, white blood cell (WBC) count, procalcitonin (PCT) level,and high sensitivity C- reactive protein (hs-CRP) were measured on the 1st day and 3rd day. The length of antibiotics treatment, duration of mechanical ventilation, and the time of ICU stay were recorded for both groups.

RESULTS: There were 512 qualified sputum specimens for culture, from which 336 pathogens were found, and 358 strains of pathogenic bacteria were found from microscopic examination of 512 qualified sputum smear. The coincidence rate of results of bedside examination of sputum smear and that of sputum culture was 78.32%(401/512). The diagnostic acumen of the former was 85.42% (287/336), specificity was 64.77% (114/176), positive predictive value was 80.17% (287/358), and negative predictive value was 74.03% (114/154). On the 1st day, no statistical differences in infection index between the two groups could be found, but on the 3rd day, the results were significantly improved in both groups. Compared with the empirical treatment group, the body temperature, WBC, PCT and hs-CRP in the target treatment group were significantly lower [body temperature (centigrade): 36.83 ± 0.69 vs. 37.64 ± 0.71, WBC (× 10⁹/L): 7.91 ± 2.75 vs. 9.66 ± 3.39, PCT (μg/L): 7.14 ± 3.89 vs. 10.14 ± 4.32, hs-CRP (mg/L): 12.24 ± 6.28 vs. 15.54 ± 5.94, P<0.05 or P<0.01]. Compared with the empirical treatment group, the time of antibiotics use(days: 6.00 ± 2.55 vs. 9.20 ± 3.46), the duration of mechanical ventilation (days: 5.00 ± 1.73 vs. 7.00 ± 1.94), and the length of ICU stay (days: 7.43 ± 1.72 vs. 12.57 ± 4.16) were significantly shortened (P<0.05 or P<0.01).

CONCLUSIONS: The results of bedside sputum examination and sputum culture showed a good correlation, and the former is helpful in early diagnosis and treatment of VAP. The result of high quality sputum smear in significant in guiding the first choice of antibiotics, reduce the time of antibiotic use, shorten the duration of mechanical ventilation and the length of ICU stay, and improve the outcome of the patients.