| Objective: To evaluate the value of quantitative culture of multi-drug resistant(MDR)bacteria and bronchial mucosa biopsy in the differential diagnosis of colonization and infection with multi-drug resistance bacteria by giving intubated or tracheotomied patient bronchoscopes detection. At the same time, some clinical information of the two groups was analyzed to provide evidence for giving intubated patients rational therapy and preventing them from the infection of MDR bacteria.Methods: The study was conducted from May. 2010 to Mar. 2011. All the patients were admitted to Respiratory Intensive Care Unite(RICU)and on mechanical ventilation for more than 48 hours. The culture of sputum was MDR Pseudomonas aeruginosa or Acinetobacter baumannii or both. A prospective observational cohort survey was carried out in these patients. All subjects were divided into two groups:infection group and colonization group according to the clinical infection symptoms and the outcome of antibiotic therapy. When the patient's condition was stable enough to receive bronchoscopy, bronchial mucosa biopsy and bronchoscopic protected specimen brushing (PSB) were conducted after the informed consent was obtained from the patient's legally authorized representative. Histopathology examination was conducted to the biopsy tissue. Microbiological diagnosis was performed with the use of quantitative culture and we made the threshold 1×103 CFU/ml. Bacteria were identified by microbioligy method and drug sensitive test was carried out by using KB paper disk. Then the sensitivity and specificity of the two methods were analyzed. At the same time, we recorded the basic information of the patients, underlying disease, the history of using antibiotic, blood gas analysis, APACHEⅡscores of different stages(when the patients were intubated and the MDR bacteria were detected), duration of mechanical ventilation, with or without ventilator-associated pneumonia(VAP), the first time of MDR strains were detected and the prognosis information. We analyzed the information above to evaluate that whether they were different between the two groups.Results: (1) During the study period, a total of 47 patients were enrolled in this study, of which infected with 22 cases and colonized with 25 cases. 26 strains of MDR bacteria were detected from the infection group and 29 strains from the colonization group by quantitative culture of the secretion got by bronchoscopic protected specimen. Both of the two kinds of MDR bacteria could be detected from parts of the patients in both groups. The duration of invasive mechanical ventilation, length of stay, and the first time of MDR strains were detected of the infection group were longer than that of the colonization group and showed a significant difference (P<0.05). (2) 22.7% of the colonization group and 42.9% of the infection group used escalated therapy before the onset multi-drug resistance of bacteria, but there had no statistically significant. There was only one patient who used de-escalated therapy. The duration of use antibiotics after MDR bacteria were detected had no statistically significant. (3) The colonization group had 5 cases of VAP and infection group had 10 cases. The colonization group's incidence of VAP was lower than infection group (20.0% vs 45.5%, P>0.05), but there was no significant difference. And there were no differences of the prognosis between the two groups. (4) The first time of MDR strains were detected after intubated of the colonization group was 15±15d, and infection group was 7±8d. The colonization group's onset of MDR bacteria was later than infection group and the difference was statistically significant (P <0.05) .The number of patients with MDR bacteria gradually increased with the time of intubated. There were 32 cases (76.2%) that had MDR strains at the time of 14 days. Since then, the cumulative number of cases increased with a much slower rate. (5) APACHEⅡscore of the colonization group was 19.76±5.72 when intubated and 16±4.97 when MDR strains were detected and had significant difference(P<0.05). The APACHEⅡscore of the infection group at the two points had no significant difference. When MDR strains were detected, APACHEⅡscore of infection group was higher than colonization group(19.77±6.30 vs 16±4.97) and the difference was statistically significant (P=0.027). (6)The bronchial mucosa biopsy showed that inflammation was detected in 18 cases in infection group (81.8%) and 6 cases in colonization group (24.0%).The incidence of inflammation in infection group was much higher than that in colonization group (P<0.05). As the quantitative culture of multi-drug resistant bacteria got by bronchoscopic protected specimen, the positive rate of infection and colonization group were 72.7% and 28.0%. In addition, bronchial biopsy showed typical pathological changes in the majority of infection group patients and there were more inflammatory cells than that in the colonization group.(7) The combination of bronchial mucosa biopsy with microorganism quantitative cultures had higher sensitivity than microorganism quantitative cultures used alone(81.8% vs 72.7%). The specificity of combination did not become lower, and it was still 72.0%.Conclusions: (1)To reduce the incidence of colonization and onset of MDR strains, we should try our best to make the patients wean from mechanical ventilation earlier, make the ICU length of stay shouter and use antibiotics rationally. (2)When the MDR strains are detected and the patient's condition is worse, there has more possibility that the patient is infected with the bacteria.(3) Microorganism quantitative cultures got by PSB combining with bronchial mucosa biopsy is more feasible in identifying colonized or infected bacteria than microorganism quantitative cultures used alone. This provides fundamental for the choice of antibiotic in clinical work.
|
PDF Full Text Request