The Study Of Patients Of Acinetobacter Baumannii Colonized Epidemic Characteristics And Risk Factors In A Surgical ICU

ObjectivesTo descript the epidemiology of Acinetobacter baumannii in a surgical Intensive Care Unit (surgical ICU) of an university hospital; to analyze the risk factors of patients of Acinetobacter baumannii colonized; to analyze the relationships between STs by Multilocus Sqeuence Typing(MLST) scheme and drugresistance of Acinetobacter baumannii for the the clue of proper measurements of hospital infection control of Acinetobacter baumannii.MethodsFrom April 7, 2008 to July 16, 2009, this study was performmed in a surgical ICU of an university hospital in Beijing.Sampling was performed every other day according to sterilization technological specification(2006). Sampling sites included patients'body surface (forehead, nasal fossa, fold inguen, axillary fossa and other exposure sites) who stayed in the surgical ICU. China blue mediums were used to incubating bacterium, then, biochemistry test (triple sugar iron agar and citrate agar incubation) and incubation 42℃to identify Acinetobacter baumannii.129 isolates of Acinetobacter baumannii from unique positive patients were performmed susceptibility test. Susceptibility test carried by K-B slips diffusion method. 7 disks with antibiotics were selected, including cefuroxime, cefepime, cefotaxim, imipenem, amikacin, minocycline, levofloxacin.85 isolates of Acinetobacter baumannii from unique colonized patiens were chosen to perform multilocus sequence typing(MLST) scheme. The protocol of MLST was simply as follow: bacterial cultureâ†'DNA extractionâ†'7 housekeeping gene PCR amplifying and sequencingâ†'allele genes adjustedâ†'allele genes alignmentâ†'MLST wed submitionâ†'STs.Standardized questionaires were well designed to collect the patients clinical informations, including demographical characters, underlying conditions, Medical devices and procedures in and before SICU, hospital calendar, surgical, antibiotic used in SICU, and other potential hospitalized risk factors.Dichotomization variables analyzed byχ2 or Fisher exact test, properly, while multi-categorical variables by Cochran-Mantel-Haenszel test. Student's t test or Wilcoxon rank sum test was used for continuous variables analysis. Univariate and multivariate logistic regression analysis was applied to identify the potential and independent risk factors of patients of Acinetobacter baumannii colonized. Two-sided P values of equal or less than 0.05 were considered statistical significant difference. Epidata (Version 2.0) was used to establish the database. Statistical analysis was performed with SAS (SAS Institute Inc., version 8.1) and SPSS (SPSS,Chicago,IL, version 16.0).ResultsTotally, 24.52% (129/522) patients were Acinetobacter baumannii colonized, 17.82% (93/522) patients colonized in surgical ICU, 5.94%(31/522) patients colonized before surgical ICU.Among the 129 isolates of Acinetobacter baumannii from unique colonized patients, 34.88%(45/129) obtained from forehead, 27.91%(40/129) from nasal fossa, 17.05%(22/129)from axillary fossa, 14.73%(20/129)from fold inguen, 0.78%(1/129) from sputum and skin wound respectively. There was no statistical significant difference of the distribution of patients'colonized sites in and before the surgical ICU(P=0.552).Susceptibility test show: 90.70% (117/129)isolates were multidrug resistance Acinetobacter baumannii (MDRAB). 89.25% (83/93) isolates from patients who colonized in surgical ICU and 93.55% (29/31) isolates from patients who colonized before surgical ICU was MDRAB, but no significance difference between the two group (P=0.726). 96.90% isolates were cefuroxime resistant, cefotaxim 90.70%, amikacin 86.82%, cefepime 82.95%, levofloxacin 75.97%, imipenem 46.51%, minocycline (19.38%) with the lowest resistant.The differences of the 7 antibiotics resistance of the isolates which obtained in and before surgical ICU were no statistical significance (all P value >0.050).85 isolates of unique patients were carried MLST. 14 STs were found (ST75, ST90, ST91, ST92, ST118, ST137, ST138, ST191, STn1, STn3, STn4, STn6, STn7, STn9). ST137, ST138, STn1, STn3, STn4, STn6, STn7, STn9 were the new found STs. The dominace STs was ST75 (29.4%, 25/85), ST138(29.4%, 25/85). eBurst was used to find cluster. We found three subgroups, including subgroup A (T138, ST75), subgroup B (ST90, ST118, ST137, ST191, ST92), subgroup C (STn1, STn6), and 5 singletons(ST91, STn3, STn4, STn7, STn9). The imipenem resistance of subgroup A was higher than subgroup B, but no statistical significant difference(P=0.060), while the minocycline resistance of subgroup B was significant higher than subgroup A (P=0.010).73.12%(68/93)Acinetobacter baumannii colonized patients were male, significant higher than non-colonized patients(P=0.025). And there were statistical significant difference of age(means 53 vs 60, P=0.004), Apache II (medians 12 vs 11, P=0.003) between the colonization and non-colonization group.The surical ICU was moved to a new place on July 15, 2008. Number of patient's bed increased from 7 to 20. Before unit alteration, the highest colonized ratio was 35.0%, then decreased after surgical ICU moved (patients'colonized ratio 5%-15%). There were no statistical significant difference among different scale of rooms in ICU (before unit alteration P=0.362,after unit alteration P=0.694).About 25% positive patiens who colonized before surgical ICU have stayed in the department of orthopedics, surgery ward. 12.90% positive patiens colonized before surgical ICU were from out-patient clinic. Over 50% colonized patients came back to the origin wards after cared in the surgical ICU, and about 25% colonized patients discharged directly.Univariate analysis showed that index of invasive procedure in surgical ICU, catheter days in surgical ICU (days of venipuncture, days of gastric tube, days of urinary catheter, times of arterial blood pressure, breathing machine by incision of trachea, days of breathing machine by incision of trachea, days of breathing machine by mouth, days of drainage, days of vacuum aspiration, hemodialysis and days of hemodialysis), days in ICU, surgical sites infection(deep, lacune, chest, abdomen), classes of antibiotics, species of antibiotics, third generation of cephalosporins, species of cephalosporins, quinolones, species of quinolones, glycopeptides, species of glycopeptides, carbopenems, species of carbopenems, semisynthesis penicillin, species of semisynthesis penicillin, aminoglycosides, species of aminoglycosides, oxazolidinones, species of oxazolidinones, antifungal antibiotics, species of antifungal antibiotics, patients'bed transfer, times of patients'bed transfer, wound, nasogastric feeding, mixtrophism maybe the potential risk factors of patients who colonized in the surgical ICU; underlying conditions (malignant tumor), surgical, emergency type of surgical and ward alteration maybe the potential protecting factors who colonized in the surgical ICU.Multiple Logistics regression analysis took the variates which P value were equal or less than 0.050 of univeriate analysis in the model. 9 variates stayed in the model by stepwise, including days in ICU, number of sputum aspiration through artificial airway, surgical ICU removal, days of venipuncture catheter, nasogastric feeding, mixotrophism, carbopenems, oxazolidinones, glycopeptides. Adjusted sex, age, BMI, ApacheII, the independent risk factors of patients who colonized Acinetobacter baumannii in the surgical ICU included duration of ICU (P<0.001,OR(95%CI): 1.346(1.207-1.501)), number of sputum aspiration through artificial airway(P=0.011,OR(95%CI) :1.156(1.033-1.292)), mixotrophism (P<0.001,OR(95%CI): 8.181(2.779-24.078)), number of species of glycopeptides (P=0.009,OR(95%CI): 4.474(1.460-13.712)); ward alteration(P=0.014,OR(95%CI): 0.169(0.041-0.700)), carbopenems (P=0.019, OR(95%CI): 0.205(0.055-0.769)) were the predominant risk factors of Acinetobacter baumannii colonized patients。ConclusionsMDRAB was persistent epidemic in the surgical ICU. Patients'Acinetobacter baumannii colonized ratio were high in the surgical ICU.Most of Acinetobacter baumannii isolates were cephalosporins, quinolones, aminoglycosides resistance. Patients who colonized Acinetobacter baumannii before ICU were common from department of orthopaedics and surgery. The common sites of Acinetobacter baumannii colonized were nasal fossa and forehead. ST75 and ST138 were the dominant isolates. MDRAB may tend to worldwide epidemic by MLST. Cross dissemination of Acinetobacter baumannii among the wards of the university hospital, and infection control measurements were necessary. Long surgical ICU stay, more frequences of sputum aspiration through artificial airway, mixotrophism, more species of glycopeptides may increasing the probability of patient colonized MDRAB. Proper scale of surgical ICU and proper using carbopenems may decrease the probability of patient colonized MDRAB.