Clinical Analysis For Imipenem-resistant Pseudomonas Aeruginosa Infections In A Neonatal Intensive Care Unit

ObjectiveTo explore the clinical features and risk factors of imipenem-resistantPseudomonas aeruginosa (IRPA) infections in Neonatal intensive care unit(NICU) for more effective in preventing and treating IRPA infection. Ourultimate goal is to reduce the occurrence of nosocomial infections in NICU.Firstly, we retrospectively analyzed the clinical data of73patientsconfirmed IRPA infection to determine the clinical characteristics of IRPAinfection of in NICU. Secondly, by comparison with the group of patients withimipenem-susceptible P. aeruginosa (ISPA) infections, we conducted a studyto investigate the independent risk factors for IRPA infection in NICU.Materials and MethodsFrom January2008to December2011, there were totally207cases of P.aeruginosa culture positive samples in NICU. We excluded8cases because ofduplicate sampling from one individual but different organs,6cases because of good clinical condition without infection symptoms, and8cases becauseof withdrawal treatment by parents before the culture result came out.Therefore, finally188cases were enrolled for our study, with73cases IRPA,115cases ISPA. Clinical situations data of two groups were collected. Andcompared in order to find out the risk factors by chi-square test and logisticregression analysis.ResultsOur study revealed that in73cases of IRPA infection, there were49casesof patients (67.1％) with very preterm (gestational age≤32weeks), and54cases (74.0％) with very low birth weight (＜1500g). Differences ingestational age and birth weight were statistically significant betweengroups IRPA and ISPA (P＜0.001). Furthermore, after those measurement datatransformed into categorical variables for univariate analysis, we found thatthe two groups of patients were statistically significant differences ingestational age≤32weeks and birth weight＜1500g (P＜0.05).Our study showed that respiratory disease (50cases,68.5％), anemia (42,57.5％) and intracranial hemorrhage (23,31.5％) were the most commoncomplications in73cases of IRPA infection. Sixty-one cases of patients(83.6％) received central line or artery catheterization,57cases ofpatients (78.1％) in IRPA group received mechanical ventilation duringhospitalization in NICU. All patients in IRPA group had used one or more thanone kinds of broad-spectrum antibiotic2weeks before isolation of P.aeruginosa; Among them, there were53(72.6％) cases of imipenem,48(65.8％)cases of the third generation cephalosporins,35(47.9％) cases ofpiperacillin-sulbactam, and4(5.5％) cases of vancomycin respectively.Data showed that apnea (46cases,63.0％), jaundice (37,50.7％) andhypoglycemia (34,46.6％) were the most common clinical presentations in73cases of IRPA infection, followed by lethargy (27,37.0％), respiratory distress (26,35.6％), abdominal distension (24,32.9％), hyperglycemia (13,17.8％) and fever (7,9.6％). The results of laboratory tests showed thatmore than half of patients appeared increased white blood cell count (WBC)(46,63.0％), increased C-reactive protein (39,53.4％) and increasedprocalcitonin (37,50.7％). In addition, there were some patients presentedwith thrombocytopenia (26,35.6％).Data from univariate analysis showed that the risk factors for IRPAinfection in NICU were: gestational age≤32weeks, birth weight＜1500g,small for gestational age, imipenem or the third generation cephalosporinsantibiotic therapy2weeks before isolation of P. aeruginosa, and mechanicalventilation, central line or artery catheterization.The multivariate logistic regression analysis revealed an independentrisk factor was imipenem treatment within the2weeks before isolation ofP. aeruginosa (OR=6.409;95％CI,1.926-21.333).Conclusions1. Very preterm, very low birth weight infants belong to the high-risk groupsof IRPA infection in NICU.2. The predisposing factors for IRPA infection in NICU were: complications,invasive procedures and broad spectrum antibiotics.3. Clinical presentations of IRPA infection of neonatal patients in NICU arenonspecific, and laboratory tests lack specificity.4. The occurrence of nosocomial infections of IRPA in NICU hospitalizedpatients was strongly related to the treatment with imipenem.