Preliminary Analysis Of Clinical Characteristics And Influencing Factors Of Lower Resdiratory Tract Infection Of Acinetobacter Baumannii In Respiratory Intensive Care Unit

Background Acinetobacter baumannii(AB)is a common opportunistic pathogen that causes nosocomial infection and highly susceptible to drug resistance and clone transmission.Infections of Multidrug resistant Acinetobacter Baumanni(MDR-AB),extensively-drug resistent Acinetobacter Baumanni(XDR-AB)and pandrug resistent Acinetobacter Baumanni(PDR-AB)are the main causes of nosocomial infection.Among them,the prevalence of carbapenem-resistant Acinetobacter baumannii(CRAB)has become the focus of attention.The identification of colonization and infection of AB in lower respiratory tract is still difficult.Respiratory Intensive Care Unit(RICU)is the main place of infection of AB in lower respiratory tract(AB-LRTI),and there are few reports about AB-LRTI in RICU and the clinical characteristics of LRTI caused by AB with other bacteria.Therefore,we intend to collect clinical datas for the identification of colonization and infection of AB in lower respiratory tract in RICU,and retrospective analysis about the production and epidemiological characteristics of AB-LRTI.Methods We collected clinical datas from 204 patients admitted to RICU,the First Affiliated Hospital of Soochow University from September 2012 to September 2018(2012.09-2018.09),the bacteriological results were AB,of which 164 cases of AB were diagnosed and met the criteria of LRTI[1],40 cases were considered for colonization of AB.The patient's bacteriological specimens were derived from sputum,lower respiratory secretions or bronchoalveolar lavage,pleural effusion and blood.The definition of bacterial colonization were based on Centers for Disease Control and Prevention/National Medical Safety Network(CDC/NHSN)[2],and combined with experts' agreement on diagnosis,treatment and prevention of the infection of AB in China in 2012[3].Making a judgment on whether colonizion or infection of AB.The specific groups were as follows,only AB was isolated,defined as AB's colonization group after judgment,including 40 cases;only AB was isolated,defined as simple AB-LRTI group after judgment,including 63 cases.AB and another bacteria were isolated simultaneously,defined as AB with another bacteria's LRTI group after judgment,including 101 cases.Among them,LRTI of AB with another Gram-negative bacteria group(with another G-bacteria's LRTI group)was 60 cases,LRTI of AB with Gram-positive bacteria group(with G+ bacteria's LRTI group)was 23 cases,LRTI of AB with fungus group(with fungus's LRTI group)was 15 cases,LRTI of AB with influenza A(H1N1),Yarrowia pneumoniae,actinomycete was one case,respectively.We compared the group of AB with another bacteria's LRTI with AB's colonization group and simple AB-LRTI group,respectively;compared the group of AB with another G-bacteria's LRTI with AB's colonization group and simple AB-LRTI group,respectively;compared the group of AB with G+bacteria's LRTI with AB's colonization group and simple AB-LRTI group,respectively;compared the group of AB with fungus's LRTI with AB's colonization group and simple AB-LRTI group,respectively.To analyze and compare the clinical characteristics,influencing factors,treatment options and prognosis of each group.Results Compared with AB's colonization group,immunosuppression,more than 4 invasive procedures,specimens from bronchoalveolar lavage,90-day mortality of petients from the group of AB with another bacteria's LRTI were higher,and patients from the latter who suffered fever,yellowish sputum,pulmonary rale and septic shock were more.In laboratory tests,WBC>10×109(or<4×109),NE%>75%(or<40%),LY<1.1×109,albumin<30g/l,hs-CRP>10 mg/l,and Neutrophil-to-Lymphocyte Ratio(NLR)were higher than those in AB's colonization group(all P<0.05).The frequency of bronchoscopy and days of infusing carbapenem for the 90 days before isolating AB,and the APACHE ? score within 24 hours after admission of the group of AB with another bacteria's LRTI were higher than AB's colonization group,except for the group of AB with G+bacteria's LRTI,the other 3 groups' days from isolating AB to invasive mechanical ventilation were shorter than that of AB's colonization group(all P<0.05).The proportion of patients with invasive mechanical ventilation,the days of invasive mechanical ventilation,and the patients whose PLT<100×109 of the group of AB with another bacteria's LRTI group were higher than those in AB's colonization group,except for the group of AB with fungus's LRTI,the other 3 groups were statistically different from AB's colonization group(all P<0.05).In addition,compared with AB's colonization group,patients from the groups of AB with another bacteria's LRTI and AB with another G-bacteria's LRTI had longer ICU stays and complicated gastrointestinal bleeding(all P<0.05).Petients from the groups of AB with another G-bacteria's LRTI had longer hospital stay,and the proportion of specimens from non-respiratory passages was relatively higher than that of AB's colonization group(all P<0.05).Infusion days of carbapenem and ?-lactams/?-lactamase inhibitors for the 90 days before isolating AB,proportion of septic shock and NLR of patients from the group of AB with another bacteria's LRTI and AB with another G-bacteria's LRTI were more than that of simple AB-LRTI group(P<0.05),the frequency of bronchoscopy for the 90 days before isolating AB of the group of AB with another G-bacteria's LRTI was more than that of simple AB-LRTI group(all P<0.05).In addition,patients from the group of AB with G+bacteria's LRTI suffered fever,PLT<100×109,and 90-day mortality were higher than those in simple AB-LRTI group(all P<0.05).Patients from the group of AB with fungus's LRTI had shorter invasive mechanical ventilation days,ICU stay,and hospital stay,and had higher incidence of septic shock,NLR,and 90-day mortality than those in simple AB-LRTI group(all P<0.05).After multivariate logistic regression analysis,it was found that,more than 4 invasive procedures,or immunosuppression,or with more days of infusing carbapenem for the 90 days before isolating AB were all the independent risk factors for AB-LRTI,and the OR value was respectively 7159.789,6.65,1.202.Among the 204 isolates of AB,48 isolates were MDR-AB,18 isolates were XDR-AB,126 isolates were PDR-AB,isolates of CRAB were up to 90%,tegacycline,amikacin,cefoperazone-sulbactam with low AB resistance rates in the near stage,was 24.64%,58.0%,60.89%,respectively,the others all exceeded 70%.The following was antibacterial therapy and prognosis of 63 patients from simple AB-LRTI group,the effective rate of tigecycline mainly combined with ?-lactam/?-lactamase inhibitors was 69.2%(9/13);the effective rate of ?-lactam/?-lactamase inhibitors mainly combined with carbapenem was 50%(7/14);the effective rate of tigecycline mainly combined with carbapenem were 50%(6/12).The following was antibacterial therapy and prognosis of 60 patients from the group of AB with another G-bacteria's LRTI,the effective rate of tigecycline mainly combined with ?-lactam/?-lactamase inhibitors was 35.3%(6/17);the effective rate of carbapenem mainly combined with ?-lactams/?-lactamase inhibitors was 37.5%(3/8);the effective rate of tigecycline mainly combined with carbapenem was 33.33%(2/6).The following was antibacterial therapy and prognosis of 23 patients from the group of AB with G+bacteria's LRTI,the effective rate of mainly carbapenem was 33.33%(2/6);the effective rate of carbapenem mainly combined with ?-lactams/?-lactamase inhibitors was 20%(1/5).Conclusion Patients who were simple AB-LRTI or AB with another bacteria's LRTI in RICU had significant differences in epidemiology,clinical symptoms and laboratory indicators compared with patients with AB's colonization;For patients admitted to RICU,who suffered AB with another bacteria's LRTI were more susceptible to septic shock than simple AB-LRTI;patients who suffered AB with another G-bacteria's LRTI had features of more times of bronchoscopy for the 90 days before isolating AB and long-term use of broad-spectrum antibacterials;patients who suffered AB with fungus's LRTI had a short treatment window,high 90-day mortality,and poor prognosis;For patients admitted to RICU,who suffered more than 4 invasive procedures,or immunosuppression,or with more days of infusing carbapenem for the 90 days before isolating AB,were more susceptible to AB-LRTI;patients admitted to RICU who suffered simple AB-LRTI or AB with another G-bacteria's LRTI,tigecycline combined with ?-lactam/?-lactamase inhibitors may be the recommended one.