BACKGROUND Pyogenic ventriculitis caused by extensively drug-resistant Acinetobacter baumannii(A.baumannii)is one of the most severe complications associated with craniotomy.However,limited therapeutic options exist f...BACKGROUND Pyogenic ventriculitis caused by extensively drug-resistant Acinetobacter baumannii(A.baumannii)is one of the most severe complications associated with craniotomy.However,limited therapeutic options exist for the treatment of A.baumannii ventriculitis due to the poor penetration rate of most antibiotics through the blood-brain barrier.CASE SUMMARY A 68-year-old male patient with severe traumatic brain injury developed pyogenic ventriculitis on postoperative day 24 caused by extensively drug-resistant A.baumannii susceptible to tigecycline only.Successful treatment was accomplished through multi-route administration of tigecycline,including intravenous combined with continuous ventricular irrigation plus intraventricular administration.The pus was cleared on the 3rd day post-irrigation,and cerebrospinal fluid cultures were negative after 12 d.CONCLUSION Our findings suggest that multi-route administration of tigecycline can be a therapeutic option against pyogenic ventriculitis caused by extensively drugresistant A.baumannii.展开更多
BACKGROUND Nosocomial infections with carbapenem-resistant Acinetobacter baumanniicalcoaceticus complex(ABC)strains are great problem for intensive care units.ABC strains can develop resistance to all the antibiotics ...BACKGROUND Nosocomial infections with carbapenem-resistant Acinetobacter baumanniicalcoaceticus complex(ABC)strains are great problem for intensive care units.ABC strains can develop resistance to all the antibiotics available.Carbapenem resistance is common and colistin resistance is rare in our country.Knowing the risk factors for colistin resistance is important since colistin seems to be the only remaining therapeutic option for the patients with pneumonia due to extensively drug resistant ABC for our country.AIM To investigate the comparison of clinical responses and outcomes between pneumonia patients with colistin-susceptible and-resistant Acinetobacter sp.Strains.METHODS During the study period,108 patients with pneumonia due to colistin-susceptible strains and 16 patients with colistin-resistant strains were included retrospectively.Continuous variables were compared with the Mann-Whitney U test,and categorical variables were compared using Pearson’s chi-square test or Fisher’s Exact chi-square test for two groups.A binary logistic regression model was developed to identify the potential independent factors associated with colistin resistance in patients with colistin-resistant strains.RESULTS High Acute Physiology and Chronic Health Evaluation II scores(OR=1.9,95%CI:1.4-2.7;P<0.001)and prior receipt of teicoplanin(OR=8.1,95%CI:1.0-63.3;P=0.045)were found to be independent risk factors for infection with colistin-resistant Acinetobacter sp.Different combinations of antibiotics including colistin,meropenem,ampicillin/sulbactam,amikacin and trimethoprim/sulfamethoxazole were used for the treatment of patients with colistin-resistant strains.Although the median duration of microbiological cure(P<0.001)was longer in the colistin-resistant group,clinical(P=0.703),laboratory(P=0.277),radiological(P=0.551),microbiological response(P=1.000)and infection related mortality rates(P=0.603)did not differ between the two groups.Among the patients with infections due to colistin-resistant strains,seven were treated with antibiotic combinations that included sulbactam.Clinical(6/7)and microbiological(5/7)response rates were quite high in these patients.CONCLUSION The optimal therapy regimen is unclear for colistin-resistant Acinetobacter sp.infections.Although combinations with sulbactam seems to be more effective in our study patients,data supporting the usefulness of combinations with sulbactam is very limited.展开更多
We report an atypical case of anti-N-methyl-D-aspartate receptor encephalitis(ANMDARE). A 27-year-old man diagnosed with ANMDARE received immunotherapy and had a good recovery. However, within one month, he developed ...We report an atypical case of anti-N-methyl-D-aspartate receptor encephalitis(ANMDARE). A 27-year-old man diagnosed with ANMDARE received immunotherapy and had a good recovery. However, within one month, he developed severe status epilepticus and decreased level of conscience with new hyperpyrexia and dyspnea, and was admitted to the emergency intensive care unit. Acinetobacter baumanii were found in the sputum culture; and anti-NMDAR antibodies were positive(titer: 1/80) in the cerebrospinal fluid. Repeated immunotherapy was administered with antibacterial agents, and the patient recovered except for mild psychiatric sequelae. This is the first report of ANMDARE that aggravates after acinetobacter baumannii pneumonia. Awareness and knowledge of this disorder should be extended, especially in the emergency medicine community.展开更多
With beta-lactam drugs and immunosuppressants widely used, the infection caused by Acinetobacter baumannfi (Ab) has become more and more serious with multidrug resistant Acinetobacter baumannfi (MDRAb) emerging an...With beta-lactam drugs and immunosuppressants widely used, the infection caused by Acinetobacter baumannfi (Ab) has become more and more serious with multidrug resistant Acinetobacter baumannfi (MDRAb) emerging and worsening rapidly. Compared with other patients, the incidence and multidrug resistance of MDRAb are higher in children in pediatric intensive care unit (PICU) because of immune deficiency, severe basic diseases, prolonged hospitalization and invasive operations. Hence it is significant to study the epidemiology and changes of antibacterial susceptibility in order to reduce the incidence of MDRAb in children. A total 115 patients with MDRAb pneumonia and 45 patients with negative MDRAb (NMDRAb) pneumonia who had been treated from January 2009 to August 2011 were studied retrospectively at the PICU of Wuhan Children's Hospital. Clinical data were analyzed with univariate and multivariate Logistic regression. In 176 clinical strains of Acinetobacter baumannfi isolated, there were 128 strains of MDRAb, accounting for 72.73%. Drug susceptibility tests showed that the resistance rates of 13-1actam antibiotics were more than 70% except for cefoperazone sulbactam. The rates to carbapenems were higher than 90%. They were significantly higher than those of NMDRAb. Amikacin, levofloxacin, ciprofloxacin and minocycline had the lowest drug-resistance rates (〈20%). Multivariate Logistic regression revealed that ICU stay, the time of mechanical ventilation, anemia, hypoproteinemia and the use of carbapenems were independent risk factors for MDRAb pneumonia. MDRAb is an important opportunistic pathogen to pneumonia in PICU, and its drug-resistance is severe. It increases significantly the mortality of patients. It is important to take the effective prevention measures for controlling it.展开更多
Background: The emergence of carbapenemase producing Acinetobacter baumannii is increasingly reported nowadays and constitutes a major problem to the intensive care unit (ICU) patients with notable extensive-drug resi...Background: The emergence of carbapenemase producing Acinetobacter baumannii is increasingly reported nowadays and constitutes a major problem to the intensive care unit (ICU) patients with notable extensive-drug resistance ability. The study investigates carbapenemase producing A. baumannii strains exhibiting an extensively drug-resistant (XDR) phenotype, isolated from ICU patients in Khartoum. Methods: A total of 100 nonduplicate Gram-negative coccobacilli strains were obtained from microbiology laboratory of ICU patients’ clinical isolates. Molecular identification of A. baumannii was performed by targeting 16S rRNA gene using specifically designed primers. Then, XDR strains were determined by susceptibility testing (disc diffusion). For detection of carbapenemase genes Polymerase chain reaction (PCR) was carried out. Result: Of 100 ICU clinical isolates, 38 (38.0%) was confirmed A. baumannii strains, those strains showed 100% carbapenem resistance and 60.5% extensive drug resistance to the antibiotics tested. The frequency of carbapenemase producer was 57.9% (22/38) of carbapenem resistance A. baumannii (CRAB). The most common carbapenemase associated with resistance was blaOXA gene followed by blaNDM and blaGES A. baumannii isolates. The co-occurrence of blaOXA-48-like and blaNDM, blaOXA-23-like and blaOXA-51, and blaNDM-1 and blaOXA-51 was detected in 22.7%, 18.2% strains and 4.5% respectively. A unique characteristic of our findings was the coharbouring of the genes blaNDM-1, blaOXA-23-like, blaOXA-51 and blaOXA-143 in 9.1% strains (2/22), and this was the first report in the Khartoum city, Sudan. Conclusion: We have demonstrated for the first time a high prevalence of XDR-carbapenemase producing A. baumannii clinical isolates from ICU patients in Khartoum. Also an emergent blaOXA-143 was reported as High-Risk Clones. This highlights the routine mentoring of XDR-carbapenemase producing A. baumannii to avoid clone dissemination in our region hospitals.展开更多
Background Multidrug-resistant Acinetobacter baumannii (MDRAB) is an important and emerging hospital-acquired pathogen worldwide. This study was conducted to identify the sources of MDRAB and its role in respiratory...Background Multidrug-resistant Acinetobacter baumannii (MDRAB) is an important and emerging hospital-acquired pathogen worldwide. This study was conducted to identify the sources of MDRAB and its role in respiratory tract colonization and nosocomial pneumonia in intensive care unit (ICU) patients. Methods We conducted a prospective active surveillance study of MDRAB in three ICUs at a Chinese Hospital from April to August 2011, to identify the sources of MDRAB and its role in respiratory tract colonization and nosocomial pneumonia. Results One hundred and fourteen (13.0%) MDRAB isolates were detected from 876 specimens, with a sensitivity of 11.6% (55/474) in screening of the pharyngeal and tracheal swabs, and 14.7% (59/402) of the sputum/endotracheal aspirates. MDRAB colonization/infection was found in 34 (26.8%) of 127 patients, including 16 (12.6%) cases of pure colonization and 18 (14.2%) cases of pneumonia (two pre-ICU-acquired cases of pneumonia and 16 ICU-acquired cases of pneumonia). Previous respiratory tract MDRAB colonization was found in 22 (17.3%) patients: eight (6.3%) were pre-ICU-acquired colonization and 14 (11.0%)ICU-acquired colonization. Of eight pre-ICU-colonized patients, five were transferred from other wards or hospitals with hospitalization 〉72 hours, and three came from the community with no previous hospitalization. Overall, 6/22 colonized patients presented with secondary pneumonia; only two (9.1%) colonized MDRAB strains were associated with secondary infections. Respiratory tract MDRAB colonization had no significant relationship with nosocomial pneumonia (P=0.725). In addition, acute respiratory failure, mechanical ventilation, renal failure, and prior carbapenem use were risk factors for MDRAB colonization/infection. Conclusions A high proportion of cases of MDRAB colonization/infection in ICU patients were detected through screening cultures. About one-third were acquired from general wards and the community before ICU admission. The low incidence of MDRAB colonization-related pneumonia questions the appropriateness of targeted antibiotic therapy.展开更多
Background Acinetobacter baumannfi has emerged as an important pathogen related to serious infections and nosocomial outbreaks around the world. However, of the frequently used methods, pulsed-field gel electrophores...Background Acinetobacter baumannfi has emerged as an important pathogen related to serious infections and nosocomial outbreaks around the world. However, of the frequently used methods, pulsed-field gel electrophoresis (PFGE) and amplified fragment length polymorphism (AFLP) in Acinetobacter baumannfi genotyping lack the direct molecular proof of drug resistance. This study was conducted to establish a typing method based on drug resistant gene identification in contrast to traditional PFGE and AFLP in the period of nosocomial epidemic or outbreak. Methods From January 2005 to October 2005, twenty-seven strains of Acinetobacter species from Intensive Care Units, the Second Affiliated Hospital in Ningbo were isolated, including both epidemic and sporadic events. Susceptibility test, PFGE, AFLP and drug resistance gene typing (DRGT) were carried out to confirm the drug resistance and analyze the genotyping, respectively. PFGE was used as a reference to evaluate the typeability of DRGT and AFLP. Results Twenty-seven strains of Acinetobacter displayed multiple antibiotic resistance and drug resistant genes, and β-1actamase genes were detected in 85.2% strains. The result of DRGT was comparable to PFGE in Acinetobacter strains with different drug resistance though a little difference existed, and even suggested a molecular evolution course of different drug-resistant strains. AFLP showed great polymorphism between strains and had weak ability in distinguishing the drug resistance. Conclusion Compared to AFLP and PFGE, DRGT is useful to analyze localized molecular epidemiology of nosocomial infections and outbreaks, which would benefit clinical diagnosis and therapy.展开更多
Background:Acinetobacter baumannii(A.baumannii)has become one of the most important opportunistic pathogens inducing nosocomial pneumonia and increasing mortality in critically ill patients recently.The interaction be...Background:Acinetobacter baumannii(A.baumannii)has become one of the most important opportunistic pathogens inducing nosocomial pneumonia and increasing mortality in critically ill patients recently.The interaction between A.baumannii infection and immune response can influence the prognosis of A.baumannii related pneumonia.The target of the present study was to investigate the role of immunodeficiency in A.baumannii induced pneumonia.Methods:Male BALB/c mice were randomly divided into the normal immunity control(NIC)group,normal immunity infection(NIA)group,immune compromised control(CIC)group,and immune compromised infection(CIA)group(n=15 for each group).Intraperitoneal injection of cyclophosphamide and intranasal instillation of A.baumannii solution were used to induce compromised immunity and murine pneumonia,respectively.The mice were sacrificed at 6 and 24 h later and the specimens were collected for further tests.Seven-day mortality of mice was also assessed.Results:After A.baumannii stimulation,the recruitment of neutrophils in mice with normal immunity increased sharply(P=0.030 at 6 h),while there was no significant raise of neutrophil counts in mice with compromised immune condition(P=0.092 at 6 h,P=0.772 at 24 h).The Th cell polarization presented with pulmonary interleukin(IL)-4 and interferon(IFN)-γlevel in response to the A.baumannii in CIA group were significantly depressed in comparison with in NIA group(IFN-γ:P=0.003 at 6 h;P=0.001 at 24 h;IL-4:P<0.001 at 6 h;P<0.001 at 24 h).The pulmonary conventional dendritic cell accumulation was even found to be inhibited after A.baumannii infection in immunocompromised mice(P=0.033).Correspondingly,A.baumannii associated pneumonia in mice with compromised immunity caused more early stage death,more severe histopathological impairment in lung.Conclusion:A.baumannii could frustrate the immune response in immunocompromised conditions,and this reduced immune response is related to more severe lung injury and worse outcome in A.baumannii induced pneumonia.展开更多
文摘BACKGROUND Pyogenic ventriculitis caused by extensively drug-resistant Acinetobacter baumannii(A.baumannii)is one of the most severe complications associated with craniotomy.However,limited therapeutic options exist for the treatment of A.baumannii ventriculitis due to the poor penetration rate of most antibiotics through the blood-brain barrier.CASE SUMMARY A 68-year-old male patient with severe traumatic brain injury developed pyogenic ventriculitis on postoperative day 24 caused by extensively drug-resistant A.baumannii susceptible to tigecycline only.Successful treatment was accomplished through multi-route administration of tigecycline,including intravenous combined with continuous ventricular irrigation plus intraventricular administration.The pus was cleared on the 3rd day post-irrigation,and cerebrospinal fluid cultures were negative after 12 d.CONCLUSION Our findings suggest that multi-route administration of tigecycline can be a therapeutic option against pyogenic ventriculitis caused by extensively drugresistant A.baumannii.
文摘BACKGROUND Nosocomial infections with carbapenem-resistant Acinetobacter baumanniicalcoaceticus complex(ABC)strains are great problem for intensive care units.ABC strains can develop resistance to all the antibiotics available.Carbapenem resistance is common and colistin resistance is rare in our country.Knowing the risk factors for colistin resistance is important since colistin seems to be the only remaining therapeutic option for the patients with pneumonia due to extensively drug resistant ABC for our country.AIM To investigate the comparison of clinical responses and outcomes between pneumonia patients with colistin-susceptible and-resistant Acinetobacter sp.Strains.METHODS During the study period,108 patients with pneumonia due to colistin-susceptible strains and 16 patients with colistin-resistant strains were included retrospectively.Continuous variables were compared with the Mann-Whitney U test,and categorical variables were compared using Pearson’s chi-square test or Fisher’s Exact chi-square test for two groups.A binary logistic regression model was developed to identify the potential independent factors associated with colistin resistance in patients with colistin-resistant strains.RESULTS High Acute Physiology and Chronic Health Evaluation II scores(OR=1.9,95%CI:1.4-2.7;P<0.001)and prior receipt of teicoplanin(OR=8.1,95%CI:1.0-63.3;P=0.045)were found to be independent risk factors for infection with colistin-resistant Acinetobacter sp.Different combinations of antibiotics including colistin,meropenem,ampicillin/sulbactam,amikacin and trimethoprim/sulfamethoxazole were used for the treatment of patients with colistin-resistant strains.Although the median duration of microbiological cure(P<0.001)was longer in the colistin-resistant group,clinical(P=0.703),laboratory(P=0.277),radiological(P=0.551),microbiological response(P=1.000)and infection related mortality rates(P=0.603)did not differ between the two groups.Among the patients with infections due to colistin-resistant strains,seven were treated with antibiotic combinations that included sulbactam.Clinical(6/7)and microbiological(5/7)response rates were quite high in these patients.CONCLUSION The optimal therapy regimen is unclear for colistin-resistant Acinetobacter sp.infections.Although combinations with sulbactam seems to be more effective in our study patients,data supporting the usefulness of combinations with sulbactam is very limited.
文摘We report an atypical case of anti-N-methyl-D-aspartate receptor encephalitis(ANMDARE). A 27-year-old man diagnosed with ANMDARE received immunotherapy and had a good recovery. However, within one month, he developed severe status epilepticus and decreased level of conscience with new hyperpyrexia and dyspnea, and was admitted to the emergency intensive care unit. Acinetobacter baumanii were found in the sputum culture; and anti-NMDAR antibodies were positive(titer: 1/80) in the cerebrospinal fluid. Repeated immunotherapy was administered with antibacterial agents, and the patient recovered except for mild psychiatric sequelae. This is the first report of ANMDARE that aggravates after acinetobacter baumannii pneumonia. Awareness and knowledge of this disorder should be extended, especially in the emergency medicine community.
文摘With beta-lactam drugs and immunosuppressants widely used, the infection caused by Acinetobacter baumannfi (Ab) has become more and more serious with multidrug resistant Acinetobacter baumannfi (MDRAb) emerging and worsening rapidly. Compared with other patients, the incidence and multidrug resistance of MDRAb are higher in children in pediatric intensive care unit (PICU) because of immune deficiency, severe basic diseases, prolonged hospitalization and invasive operations. Hence it is significant to study the epidemiology and changes of antibacterial susceptibility in order to reduce the incidence of MDRAb in children. A total 115 patients with MDRAb pneumonia and 45 patients with negative MDRAb (NMDRAb) pneumonia who had been treated from January 2009 to August 2011 were studied retrospectively at the PICU of Wuhan Children's Hospital. Clinical data were analyzed with univariate and multivariate Logistic regression. In 176 clinical strains of Acinetobacter baumannfi isolated, there were 128 strains of MDRAb, accounting for 72.73%. Drug susceptibility tests showed that the resistance rates of 13-1actam antibiotics were more than 70% except for cefoperazone sulbactam. The rates to carbapenems were higher than 90%. They were significantly higher than those of NMDRAb. Amikacin, levofloxacin, ciprofloxacin and minocycline had the lowest drug-resistance rates (〈20%). Multivariate Logistic regression revealed that ICU stay, the time of mechanical ventilation, anemia, hypoproteinemia and the use of carbapenems were independent risk factors for MDRAb pneumonia. MDRAb is an important opportunistic pathogen to pneumonia in PICU, and its drug-resistance is severe. It increases significantly the mortality of patients. It is important to take the effective prevention measures for controlling it.
文摘Background: The emergence of carbapenemase producing Acinetobacter baumannii is increasingly reported nowadays and constitutes a major problem to the intensive care unit (ICU) patients with notable extensive-drug resistance ability. The study investigates carbapenemase producing A. baumannii strains exhibiting an extensively drug-resistant (XDR) phenotype, isolated from ICU patients in Khartoum. Methods: A total of 100 nonduplicate Gram-negative coccobacilli strains were obtained from microbiology laboratory of ICU patients’ clinical isolates. Molecular identification of A. baumannii was performed by targeting 16S rRNA gene using specifically designed primers. Then, XDR strains were determined by susceptibility testing (disc diffusion). For detection of carbapenemase genes Polymerase chain reaction (PCR) was carried out. Result: Of 100 ICU clinical isolates, 38 (38.0%) was confirmed A. baumannii strains, those strains showed 100% carbapenem resistance and 60.5% extensive drug resistance to the antibiotics tested. The frequency of carbapenemase producer was 57.9% (22/38) of carbapenem resistance A. baumannii (CRAB). The most common carbapenemase associated with resistance was blaOXA gene followed by blaNDM and blaGES A. baumannii isolates. The co-occurrence of blaOXA-48-like and blaNDM, blaOXA-23-like and blaOXA-51, and blaNDM-1 and blaOXA-51 was detected in 22.7%, 18.2% strains and 4.5% respectively. A unique characteristic of our findings was the coharbouring of the genes blaNDM-1, blaOXA-23-like, blaOXA-51 and blaOXA-143 in 9.1% strains (2/22), and this was the first report in the Khartoum city, Sudan. Conclusion: We have demonstrated for the first time a high prevalence of XDR-carbapenemase producing A. baumannii clinical isolates from ICU patients in Khartoum. Also an emergent blaOXA-143 was reported as High-Risk Clones. This highlights the routine mentoring of XDR-carbapenemase producing A. baumannii to avoid clone dissemination in our region hospitals.
文摘Background Multidrug-resistant Acinetobacter baumannii (MDRAB) is an important and emerging hospital-acquired pathogen worldwide. This study was conducted to identify the sources of MDRAB and its role in respiratory tract colonization and nosocomial pneumonia in intensive care unit (ICU) patients. Methods We conducted a prospective active surveillance study of MDRAB in three ICUs at a Chinese Hospital from April to August 2011, to identify the sources of MDRAB and its role in respiratory tract colonization and nosocomial pneumonia. Results One hundred and fourteen (13.0%) MDRAB isolates were detected from 876 specimens, with a sensitivity of 11.6% (55/474) in screening of the pharyngeal and tracheal swabs, and 14.7% (59/402) of the sputum/endotracheal aspirates. MDRAB colonization/infection was found in 34 (26.8%) of 127 patients, including 16 (12.6%) cases of pure colonization and 18 (14.2%) cases of pneumonia (two pre-ICU-acquired cases of pneumonia and 16 ICU-acquired cases of pneumonia). Previous respiratory tract MDRAB colonization was found in 22 (17.3%) patients: eight (6.3%) were pre-ICU-acquired colonization and 14 (11.0%)ICU-acquired colonization. Of eight pre-ICU-colonized patients, five were transferred from other wards or hospitals with hospitalization 〉72 hours, and three came from the community with no previous hospitalization. Overall, 6/22 colonized patients presented with secondary pneumonia; only two (9.1%) colonized MDRAB strains were associated with secondary infections. Respiratory tract MDRAB colonization had no significant relationship with nosocomial pneumonia (P=0.725). In addition, acute respiratory failure, mechanical ventilation, renal failure, and prior carbapenem use were risk factors for MDRAB colonization/infection. Conclusions A high proportion of cases of MDRAB colonization/infection in ICU patients were detected through screening cultures. About one-third were acquired from general wards and the community before ICU admission. The low incidence of MDRAB colonization-related pneumonia questions the appropriateness of targeted antibiotic therapy.
文摘Background Acinetobacter baumannfi has emerged as an important pathogen related to serious infections and nosocomial outbreaks around the world. However, of the frequently used methods, pulsed-field gel electrophoresis (PFGE) and amplified fragment length polymorphism (AFLP) in Acinetobacter baumannfi genotyping lack the direct molecular proof of drug resistance. This study was conducted to establish a typing method based on drug resistant gene identification in contrast to traditional PFGE and AFLP in the period of nosocomial epidemic or outbreak. Methods From January 2005 to October 2005, twenty-seven strains of Acinetobacter species from Intensive Care Units, the Second Affiliated Hospital in Ningbo were isolated, including both epidemic and sporadic events. Susceptibility test, PFGE, AFLP and drug resistance gene typing (DRGT) were carried out to confirm the drug resistance and analyze the genotyping, respectively. PFGE was used as a reference to evaluate the typeability of DRGT and AFLP. Results Twenty-seven strains of Acinetobacter displayed multiple antibiotic resistance and drug resistant genes, and β-1actamase genes were detected in 85.2% strains. The result of DRGT was comparable to PFGE in Acinetobacter strains with different drug resistance though a little difference existed, and even suggested a molecular evolution course of different drug-resistant strains. AFLP showed great polymorphism between strains and had weak ability in distinguishing the drug resistance. Conclusion Compared to AFLP and PFGE, DRGT is useful to analyze localized molecular epidemiology of nosocomial infections and outbreaks, which would benefit clinical diagnosis and therapy.
基金supported by grants from the National Natural Science Foundations of China(No.81300060)Specialized Research Fund for the Doctoral Program of Higher Education of China(No.20130092120070)。
文摘Background:Acinetobacter baumannii(A.baumannii)has become one of the most important opportunistic pathogens inducing nosocomial pneumonia and increasing mortality in critically ill patients recently.The interaction between A.baumannii infection and immune response can influence the prognosis of A.baumannii related pneumonia.The target of the present study was to investigate the role of immunodeficiency in A.baumannii induced pneumonia.Methods:Male BALB/c mice were randomly divided into the normal immunity control(NIC)group,normal immunity infection(NIA)group,immune compromised control(CIC)group,and immune compromised infection(CIA)group(n=15 for each group).Intraperitoneal injection of cyclophosphamide and intranasal instillation of A.baumannii solution were used to induce compromised immunity and murine pneumonia,respectively.The mice were sacrificed at 6 and 24 h later and the specimens were collected for further tests.Seven-day mortality of mice was also assessed.Results:After A.baumannii stimulation,the recruitment of neutrophils in mice with normal immunity increased sharply(P=0.030 at 6 h),while there was no significant raise of neutrophil counts in mice with compromised immune condition(P=0.092 at 6 h,P=0.772 at 24 h).The Th cell polarization presented with pulmonary interleukin(IL)-4 and interferon(IFN)-γlevel in response to the A.baumannii in CIA group were significantly depressed in comparison with in NIA group(IFN-γ:P=0.003 at 6 h;P=0.001 at 24 h;IL-4:P<0.001 at 6 h;P<0.001 at 24 h).The pulmonary conventional dendritic cell accumulation was even found to be inhibited after A.baumannii infection in immunocompromised mice(P=0.033).Correspondingly,A.baumannii associated pneumonia in mice with compromised immunity caused more early stage death,more severe histopathological impairment in lung.Conclusion:A.baumannii could frustrate the immune response in immunocompromised conditions,and this reduced immune response is related to more severe lung injury and worse outcome in A.baumannii induced pneumonia.