Acinetobacter baumannii(A. baumannii) is undoubtedly one of the most successful pathogens in the modern healthcare system. With invasive procedures, antibiotic use and immunocompromised hosts increasing in recent year...Acinetobacter baumannii(A. baumannii) is undoubtedly one of the most successful pathogens in the modern healthcare system. With invasive procedures, antibiotic use and immunocompromised hosts increasing in recent years, A. baumannii has become endemic in hospitals due to its versatile genetic machinery, which allows it to quickly evolve resistance factors, and to its remarkable ability to tolerate harsh environments. Infections and outbreaks caused by multidrugresistant A. baumannii(MDRAB) are prevalent and have been reported worldwide over the past twenty or more years. To address this problem effectively, knowledge of species identification, typing methods, clinical manifestations, risk factors, and virulence factors is essential. The global epidemiology of MDRAB is monitored by persistent surveillance programs. Because few effective antibiotics are available, clinicians often face serious challenges when treating patients with MDRAB. Therefore, a deep understanding of the resistance mechanisms used by MDRAB can shed light on two possible strategies to combat the dissemination of antimicrobial resistance: stringent infection control and antibiotic treatments, of which colistin-based combination therapy is the mainstream strategy. However, due to the current unsatisfying therapeutic outcomes, there is a great need to develop and evaluate the efficacy of new antibiotics and to understand the role of other potential alternatives, such as antimicrobial peptides, in the treatment of MDRAB infections.展开更多
Background Acinetobacter baumannii is one of the main gramnegative bacilli in clinical practice Nosocomial infections caused by multidrug resistance Acinetobacter baumannii is very difficult to treat This study was de...Background Acinetobacter baumannii is one of the main gramnegative bacilli in clinical practice Nosocomial infections caused by multidrug resistance Acinetobacter baumannii is very difficult to treat This study was designed to investigate the antimicrobial resistance characteristics and four resistant gene expressions of aminoglycosidemodifying enzymes including Nacetyltransferases and Ophosphotransferases in Acinetobacter baumannii Methods Bacterial identification and antimicrobial susceptibility test were performed by PhoenixTM system in 247 strains of Acinetobacter baumannii Minimal inhibitory concentrations (MICs) of seven aminoglycosides including gentamicin, amikacin, kanamycin, tobramycin, netilmicin, neomycin and streptomycin in 15 strains of multidrug resistant Acinetobacter baumannii were detected by agar dilution Four aminoglycosidemodifying enzyme genes were amplified by polymerase chain reaction (PCR) and verified by DNA sequencerResults The resistance rates of 247 strains of Acinetobacter baumannii against cefotaxime, levofloxacin, piperacillin, aztreonam, tetracycline, ciprofloxacin and chloramphenicol were more than 50% Imipenem and meropenem showed high antibacterial activities with resistance rates of 32% and 41% MIC50 and MIC90 of gentamicin, amikacin, streptomycin and kanamycin in 15 strains of multidrug resistant Acinetobacter baumanii were all more than 1024 mg/L, and the resistance rates were 100%, 100%, 100% and 933%, respectively But their resistance rates to tobramycin, netilmicin and neomycin were 867%, 933% and 467%, respectively Three modifying enzyme genes, including aacC1, aacC2 and aacA4 genes, were found in 15 strains, but aphA6 had not been detected Their positive rates were 933%, 200% and 200%, respectively These three genes existed simultaneously in No19 strain Nucleotide sequences of aacC1, aacC2 and aacA4 genes shared 100%, 979% and 997% identities with GenBank genes (AY307113, S68058 and AY307114)Conclusion Multidrug resistant Acinetobacter baumannii strains展开更多
Background： Acinetobacter baumannii has emerged as an important pathogen causing a variety of infections. Using data from the China Surveillance of Antimicrobial Resistance Program conducted biennially, we investigat...Background： Acinetobacter baumannii has emerged as an important pathogen causing a variety of infections. Using data from the China Surveillance of Antimicrobial Resistance Program conducted biennially, we investigated the secular changes in the resistance of 2917 isolates ofA. baumannii from 2004 to 2014 to differ antimicrobial agents. Methods： Pathogen samples were collected from 17 to 20 hospitals located in the eastern, central, and western regions of China. Minimum inhibitory concentrations （MICs） were determined by a 2-fold agar dilution method, and antimicrobial susceptibility was established using the 2014 Clinical Laboratory Standards Institute-approved breakpoints. Isolates not susceptible to all the tested aminoglycosides, fluoroquinolones, β-lactams, β-lactam/β-lactam inhibitors and carbapenems were defined as extensively drug resistant. Results： The rates of nonsusceptibility to common antimicrobial agents remained high （〉65%） over the years with some fluctuations to certain agents. The prevalence of imipenem-resistant A. batmlannii （IRAB） increased from 13.3% in 2004 to 70.5% in 2014 and that of extensively drug-resistant A. haumannii （XDRAB） increased from I1.1% in 2004 to 60.4% in 2014. The activity of tigecycline was stable with MIC,≤4 mg/L against A. baumannii from 2009 to 2014. Susceptibility to colistin remained high （97.0%） from 2009 to 2014. The prevalence of XDRAB increased in all the three surveillance regions over the years and was significantly higher in Intensive Care Unit （ICU） wards than non-lCU wards. Conclusions： This longitudinal multicenter surveillance program revealed the nationwide emergence of A. baumnnii in China and showed a significant increase in prevalence from 2004 to 2014. High levels of bacterial resistance were detected among samples collected from clinical settings in China, with IRAB and XDRAB being especially prevalent. This study will help to guide empirical therapy and identify at-risk groups requiring more intense intervent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 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 ad展开更多
Objective:To assess and characterize antibiotic resistance in Acinetobacter baumannii strains recovered from 5 health-care facilities in Algiers.Methods:Antibiotic susceptibility testing was performed by agar diffusio...Objective:To assess and characterize antibiotic resistance in Acinetobacter baumannii strains recovered from 5 health-care facilities in Algiers.Methods:Antibiotic susceptibility testing was performed by agar diffusion and agar dilution methods,resistance genes were identified by PCR and sequencing,and molecular typing of isolates was carried out by enterobacterial repetitive intergenic consensus-PCR(ERIC-PCR).Results:Among 125 tested isolates,117(93.6% ) were multidrug-resistant.of which 94(75.2% ) were imipenem resistant.The bla_(ADC)and bla_(OXA-51-like) genes were detected in all isolates,in association with ISAba I sequence in 84% and 8% (imipenem resistant) of isolates,respectively.The bla_(OXA-23-like) and bla_(OXA-24-like)carbapenemase genes were delected in 67.02% and 20.21% of imipenem-resistant isolates,respectively.The bla_(OXA-23-like) gene is linked to ISAba1 or ISAba4 elements.The metallo-β-lactamase NDM-1 gene was found in 10(10.6% ) imipenem-resisianl strains from three hospitals,it is linked to ISAba125 clement in nine strains.Extended spectrum β-lactamases production was not detected.Imipenem and cefotaxime resistance phenolypes could not be transferred to Escherichia coli by conjugation.Outer membrane protein CarO gene was not delected in four imipenem-resisianl isolates.The aac(6')-1b.sul1,sul2,tetA and tetB genes were present in 5.31% .36.17% .77.65% .1.06% and 65.92% of strains,respectively.Class 1 integrons were detected in 23.4% strains.KRIC-PCR typing showed a genetic diversity among bla_(OXA-23-like) and bla_(OXA-24-like) positive strains,while clonality was observed among bla_(NDM-1)positives.Conclusions:This study highlighted the high prevalence of imipenem resistance in Acinetobacter baumannii in Algiers hospitals mediated mainly by bla_(OXA-23-like),bla_(OXA-24-like),and bla_(NDM-1) genes.展开更多
Objective: To check biofilm formation by Acinetobacter baumannii(A. baumannii)clinical isolates and show their susceptibility to different antibiotics and investigate a possible link between establishment of biofilm a...Objective: To check biofilm formation by Acinetobacter baumannii(A. baumannii)clinical isolates and show their susceptibility to different antibiotics and investigate a possible link between establishment of biofilm and multidrug resistance.Methods: This study was performed on clinical samples collected from patients with nosocomial infections in three hospitals of Tehran. Samples were initially screened by culture and biochemical tests for the presence of different species of Acinetobacter. Identifications were further confirmed by PCR assays. Their susceptibilities to 11 antibiotics of different classes were determined by disc diffusion method according to Clinical and Laboratory Standards Institute guidelines. The ability to produce biofilm was investigated using methods: culture on Congo red agar, microtiter plate, and test tube method.Results: From the overall clinical samples, 156 specimens were confirmed to contain A. baumannii. The bacteria were highly resistant to most antibiotics except polymyxin B.Of these isolates, 10.26% were able to produce biofilms as shown on Congo red agar.However, the percentage of bacteria with positive biofilm in test tube, standard microtiter plate, and modified microtiter plate assays were 48.72%, 66.66%, and 73.72%, respectively. At least 92% of the biofilm forming isolates were multidrug resistant.Conclusions: Since most of the multidrug resistant strains produce biofilm, it seems necessary to provide continuous monitoring and determination of antibiotic susceptibility of clinical A. baumannii. This would help to select the most appropriate antibiotic for treatment.展开更多
Background:Intracranial infection after craniotomy is one of the most serious postoperative complications,especially multidrug-resistant(MDR)or extensively drug-resistant(XDR)bacterial meningitis,and strongly affects ...Background:Intracranial infection after craniotomy is one of the most serious postoperative complications,especially multidrug-resistant(MDR)or extensively drug-resistant(XDR)bacterial meningitis,and strongly affects the prognosis of patients.Current treatment experience regarding these infections is scarce.Case presentation:We report a case of severe intracranial infection of XDR Acinetobacter baumannii(A.baumannii)that was treated by intravenous(IV)injection,sequential intraventricular(IVT)injection of tigecycline and polymyxin B,and other anti-infective drugs.Good results were obtained,and the patient was eventually discharged from the hospital.This case is characterized by intracranial infection.Conclusions:The polymyxin B IV+IVT pathway is an ideal treatment strategy for XDR A.baumannii.The tigecycline IVT pathway is also a safe treatment option.展开更多
Acinetobacter baumannii causes serious infections especially in immunocompromised and/or hospitalized patients.Several A.baumannii strains are multidrug resistant and infect wounds,bones,and the respiratory tract.Curr...Acinetobacter baumannii causes serious infections especially in immunocompromised and/or hospitalized patients.Several A.baumannii strains are multidrug resistant and infect wounds,bones,and the respiratory tract.Current studies are focused on finding new effective agents against A.baumannii.Phage therapy is a promising means to fight this bacterium and many studies on procuring and applying new phages against A.baumannii are currently being conducted.As shown in animal models,phages against multidrug-resistant A.baumannii may control bacterial infections caused by this pathogen and may be a real hope to solve this dangerous health problem.展开更多
Pan-drug resistant Acinetobacter baumannii(A.baumannii)(PDRAB)is resistant to all currently-available antimicrobials(including carbapenems),with the exception of colistin(polymyxin).Recently,PDRAB
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展开更多
Objective:To record surveillance,antibiotic resistance of uropathogens of hospitalized patients over a period of 18 months.Methods:Urine samples from wards and cabins were used for isolating urinary tract infection(UT...Objective:To record surveillance,antibiotic resistance of uropathogens of hospitalized patients over a period of 18 months.Methods:Urine samples from wards and cabins were used for isolating urinary tract infection(UTI)-causing bacteria that were cultured on suitable selective media and identified by biochemical tests;and their antibiograms were ascertained by Kirby-Bauer's disc diffusion method,in each 6-month interval of the study period,using 18 antibiotics of five different classes.Results:From wards and cabins,1 245 samples were collected,from which 996 strains of bacteria belonging to 11 species were isolated,during April 2011 to September2012.Two Gram-positive,Staphylococcus aureus(S.aureus)and Enterococcus faecalis(E.faecalis),and nine Gram-negative bacteria,Acinetobacter baumannii,Citrobactcr sp.,Escherichia coli,Enterobacter aerogenes,Klebsiella pneumoniae.Klebsiella oxytoca,Proteus mirabilis,Proteus vulgaris and Pseudomonas aeruginosa were isolated.Both S.aureus and E.faecalis were vancomycin resistant,and resistant-strains of all pathogens increased in each 6-month period of study.Particularly,all Gram-negatives were resistant to nitrofurantoin and co-trimoxazole,the most preferred antibiotics of empiric therapy for UTI.Conclusions:Antibiograms of 11 UTI-causing bacteria recorded in this study indicated moderately higher numbers of strains resistant to each antibiotic studied,generating the fear of precipitating fervent episodes in public health particularly with bacteria,Acinetobacter baumannii,Escherichia coli,Klebsiella pneumoniae and S.aureus.Moreover,vancomycin resistance in strains of S.aureus and E.faecalis is a matter of concern.展开更多
Mechanisms of bacterial resistance to fluoro-quinolones may be grouped intothree principal categories: gene mutations of DNA topoisomerase Ⅱ (GyrA or GyrB), DNA topoisomeraseⅣ ( ParC or ParE), decrease of outer memb...Mechanisms of bacterial resistance to fluoro-quinolones may be grouped intothree principal categories: gene mutations of DNA topoisomerase Ⅱ (GyrA or GyrB), DNA topoisomeraseⅣ ( ParC or ParE), decrease of outer membrane permeation and upregulation of multi-drug effluxpump (active efflux system). Efflux pumps are transport proteins removing toxic substrates(including virtually all classes of clinically relevant antibiotics) from cells to the externalenvironment. These proteins exist in both Gram positive bacteria and Gram negative bacteria as wellas in fungi and mammalian (tumour) cells. It has been reported that alkaloid reserpine and carbonylcyanide m-chlorophenylhydrazone (CCCP) can inhibit NorA multi-drug efflux. In order to explore theuniversality of drug efflux in microorganisms, 85 strains of Acinetobacter baumannii (A. baumannii)were tested using reserpine and CCCP. The quinolone-resistant-determining region (QRDR) of gyrA andparC genes in 35 isolates of A. baumannii were amplified by polymerase chain reaction (PCR) andsequenced by DNA sequencer. The correlation between resistant mutation regularity and bacterial drugefflux were analysed.展开更多
BACKGROUND:The Acinetobacter baumannii group,including Acinetobacter baumannii,Acinetobacter genomospecies 3 and 13 TU,is phenotypically indistinguishable and uniformly identified as Acinetobacter baumannii by laborat...BACKGROUND:The Acinetobacter baumannii group,including Acinetobacter baumannii,Acinetobacter genomospecies 3 and 13 TU,is phenotypically indistinguishable and uniformly identified as Acinetobacter baumannii by laboratories of clinical microbiology.This review aimed to demonstrate the differences among them.METHODS:Literatures associated with the Acinetobacter baumannii group were identified and selected from PubMed databases and relevant journals.RESULTS:Acinetobacter genospecies 3 and 13 TU possess a certain proportion in clinical isolates.There were considerable differences in epidemiologic features,clinical manifestations,antimicrobial resistances and therapeutic options among the Acinetobacter baumannii group.Compared with Acinetobacter genomospecies 3 and 13 TU,Acinetobacter baumannii with a higher resistance to antimicrobial agents are easier to be treated inappropriately,and present a worse outcome in patients.CONCLUSION:The Acinetobacter baumannii group comprises three distinct clinical entities,and their clinical value are not equal.展开更多
文摘Acinetobacter baumannii(A. baumannii) is undoubtedly one of the most successful pathogens in the modern healthcare system. With invasive procedures, antibiotic use and immunocompromised hosts increasing in recent years, A. baumannii has become endemic in hospitals due to its versatile genetic machinery, which allows it to quickly evolve resistance factors, and to its remarkable ability to tolerate harsh environments. Infections and outbreaks caused by multidrugresistant A. baumannii(MDRAB) are prevalent and have been reported worldwide over the past twenty or more years. To address this problem effectively, knowledge of species identification, typing methods, clinical manifestations, risk factors, and virulence factors is essential. The global epidemiology of MDRAB is monitored by persistent surveillance programs. Because few effective antibiotics are available, clinicians often face serious challenges when treating patients with MDRAB. Therefore, a deep understanding of the resistance mechanisms used by MDRAB can shed light on two possible strategies to combat the dissemination of antimicrobial resistance: stringent infection control and antibiotic treatments, of which colistin-based combination therapy is the mainstream strategy. However, due to the current unsatisfying therapeutic outcomes, there is a great need to develop and evaluate the efficacy of new antibiotics and to understand the role of other potential alternatives, such as antimicrobial peptides, in the treatment of MDRAB infections.
文摘Background Acinetobacter baumannii is one of the main gramnegative bacilli in clinical practice Nosocomial infections caused by multidrug resistance Acinetobacter baumannii is very difficult to treat This study was designed to investigate the antimicrobial resistance characteristics and four resistant gene expressions of aminoglycosidemodifying enzymes including Nacetyltransferases and Ophosphotransferases in Acinetobacter baumannii Methods Bacterial identification and antimicrobial susceptibility test were performed by PhoenixTM system in 247 strains of Acinetobacter baumannii Minimal inhibitory concentrations (MICs) of seven aminoglycosides including gentamicin, amikacin, kanamycin, tobramycin, netilmicin, neomycin and streptomycin in 15 strains of multidrug resistant Acinetobacter baumannii were detected by agar dilution Four aminoglycosidemodifying enzyme genes were amplified by polymerase chain reaction (PCR) and verified by DNA sequencerResults The resistance rates of 247 strains of Acinetobacter baumannii against cefotaxime, levofloxacin, piperacillin, aztreonam, tetracycline, ciprofloxacin and chloramphenicol were more than 50% Imipenem and meropenem showed high antibacterial activities with resistance rates of 32% and 41% MIC50 and MIC90 of gentamicin, amikacin, streptomycin and kanamycin in 15 strains of multidrug resistant Acinetobacter baumanii were all more than 1024 mg/L, and the resistance rates were 100%, 100%, 100% and 933%, respectively But their resistance rates to tobramycin, netilmicin and neomycin were 867%, 933% and 467%, respectively Three modifying enzyme genes, including aacC1, aacC2 and aacA4 genes, were found in 15 strains, but aphA6 had not been detected Their positive rates were 933%, 200% and 200%, respectively These three genes existed simultaneously in No19 strain Nucleotide sequences of aacC1, aacC2 and aacA4 genes shared 100%, 979% and 997% identities with GenBank genes (AY307113, S68058 and AY307114)Conclusion Multidrug resistant Acinetobacter baumannii strains
文摘Background： Acinetobacter baumannii has emerged as an important pathogen causing a variety of infections. Using data from the China Surveillance of Antimicrobial Resistance Program conducted biennially, we investigated the secular changes in the resistance of 2917 isolates ofA. baumannii from 2004 to 2014 to differ antimicrobial agents. Methods： Pathogen samples were collected from 17 to 20 hospitals located in the eastern, central, and western regions of China. Minimum inhibitory concentrations （MICs） were determined by a 2-fold agar dilution method, and antimicrobial susceptibility was established using the 2014 Clinical Laboratory Standards Institute-approved breakpoints. Isolates not susceptible to all the tested aminoglycosides, fluoroquinolones, β-lactams, β-lactam/β-lactam inhibitors and carbapenems were defined as extensively drug resistant. Results： The rates of nonsusceptibility to common antimicrobial agents remained high （〉65%） over the years with some fluctuations to certain agents. The prevalence of imipenem-resistant A. batmlannii （IRAB） increased from 13.3% in 2004 to 70.5% in 2014 and that of extensively drug-resistant A. haumannii （XDRAB） increased from I1.1% in 2004 to 60.4% in 2014. The activity of tigecycline was stable with MIC,≤4 mg/L against A. baumannii from 2009 to 2014. Susceptibility to colistin remained high （97.0%） from 2009 to 2014. The prevalence of XDRAB increased in all the three surveillance regions over the years and was significantly higher in Intensive Care Unit （ICU） wards than non-lCU wards. Conclusions： This longitudinal multicenter surveillance program revealed the nationwide emergence of A. baumnnii in China and showed a significant increase in prevalence from 2004 to 2014. High levels of bacterial resistance were detected among samples collected from clinical settings in China, with IRAB and XDRAB being especially prevalent. This study will help to guide empirical therapy and identify at-risk groups requiring more intense intervent
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.
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 ad
基金supported by grants from National Fund for the Research and National Agency for the Development of Research in Health(Algeria)
文摘Objective:To assess and characterize antibiotic resistance in Acinetobacter baumannii strains recovered from 5 health-care facilities in Algiers.Methods:Antibiotic susceptibility testing was performed by agar diffusion and agar dilution methods,resistance genes were identified by PCR and sequencing,and molecular typing of isolates was carried out by enterobacterial repetitive intergenic consensus-PCR(ERIC-PCR).Results:Among 125 tested isolates,117(93.6% ) were multidrug-resistant.of which 94(75.2% ) were imipenem resistant.The bla_(ADC)and bla_(OXA-51-like) genes were detected in all isolates,in association with ISAba I sequence in 84% and 8% (imipenem resistant) of isolates,respectively.The bla_(OXA-23-like) and bla_(OXA-24-like)carbapenemase genes were delected in 67.02% and 20.21% of imipenem-resistant isolates,respectively.The bla_(OXA-23-like) gene is linked to ISAba1 or ISAba4 elements.The metallo-β-lactamase NDM-1 gene was found in 10(10.6% ) imipenem-resisianl strains from three hospitals,it is linked to ISAba125 clement in nine strains.Extended spectrum β-lactamases production was not detected.Imipenem and cefotaxime resistance phenolypes could not be transferred to Escherichia coli by conjugation.Outer membrane protein CarO gene was not delected in four imipenem-resisianl isolates.The aac(6')-1b.sul1,sul2,tetA and tetB genes were present in 5.31% .36.17% .77.65% .1.06% and 65.92% of strains,respectively.Class 1 integrons were detected in 23.4% strains.KRIC-PCR typing showed a genetic diversity among bla_(OXA-23-like) and bla_(OXA-24-like) positive strains,while clonality was observed among bla_(NDM-1)positives.Conclusions:This study highlighted the high prevalence of imipenem resistance in Acinetobacter baumannii in Algiers hospitals mediated mainly by bla_(OXA-23-like),bla_(OXA-24-like),and bla_(NDM-1) genes.
基金Supported by an educational grant for doctoral thesis from Islamic Azad University of Karaj(grant number:11530554922001)
文摘Objective: To check biofilm formation by Acinetobacter baumannii(A. baumannii)clinical isolates and show their susceptibility to different antibiotics and investigate a possible link between establishment of biofilm and multidrug resistance.Methods: This study was performed on clinical samples collected from patients with nosocomial infections in three hospitals of Tehran. Samples were initially screened by culture and biochemical tests for the presence of different species of Acinetobacter. Identifications were further confirmed by PCR assays. Their susceptibilities to 11 antibiotics of different classes were determined by disc diffusion method according to Clinical and Laboratory Standards Institute guidelines. The ability to produce biofilm was investigated using methods: culture on Congo red agar, microtiter plate, and test tube method.Results: From the overall clinical samples, 156 specimens were confirmed to contain A. baumannii. The bacteria were highly resistant to most antibiotics except polymyxin B.Of these isolates, 10.26% were able to produce biofilms as shown on Congo red agar.However, the percentage of bacteria with positive biofilm in test tube, standard microtiter plate, and modified microtiter plate assays were 48.72%, 66.66%, and 73.72%, respectively. At least 92% of the biofilm forming isolates were multidrug resistant.Conclusions: Since most of the multidrug resistant strains produce biofilm, it seems necessary to provide continuous monitoring and determination of antibiotic susceptibility of clinical A. baumannii. This would help to select the most appropriate antibiotic for treatment.
基金supported by grants from the National Natural Science Foundation of China(81571940,81741125)the Guangzhou Science and Technology Planning Project of China(201504281714528)PLA Logistics Research Project of China(CWH17L020,17CXZ008,18CXZ030)
文摘Background:Intracranial infection after craniotomy is one of the most serious postoperative complications,especially multidrug-resistant(MDR)or extensively drug-resistant(XDR)bacterial meningitis,and strongly affects the prognosis of patients.Current treatment experience regarding these infections is scarce.Case presentation:We report a case of severe intracranial infection of XDR Acinetobacter baumannii(A.baumannii)that was treated by intravenous(IV)injection,sequential intraventricular(IVT)injection of tigecycline and polymyxin B,and other anti-infective drugs.Good results were obtained,and the patient was eventually discharged from the hospital.This case is characterized by intracranial infection.Conclusions:The polymyxin B IV+IVT pathway is an ideal treatment strategy for XDR A.baumannii.The tigecycline IVT pathway is also a safe treatment option.
基金supported by the statutory funds from the Hirszfeld Institute of Immunology and Experimental Therapy, Polish Academy of Sciences
文摘Acinetobacter baumannii causes serious infections especially in immunocompromised and/or hospitalized patients.Several A.baumannii strains are multidrug resistant and infect wounds,bones,and the respiratory tract.Current studies are focused on finding new effective agents against A.baumannii.Phage therapy is a promising means to fight this bacterium and many studies on procuring and applying new phages against A.baumannii are currently being conducted.As shown in animal models,phages against multidrug-resistant A.baumannii may control bacterial infections caused by this pathogen and may be a real hope to solve this dangerous health problem.
文摘Pan-drug resistant Acinetobacter baumannii(A.baumannii)(PDRAB)is resistant to all currently-available antimicrobials(including carbapenems),with the exception of colistin(polymyxin).Recently,PDRAB
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
基金Supported by the major research project on Botany(Grant No.39-388/2010/SR)from UGC+1 种基金New Delhiawarded RN Padhy
文摘Objective:To record surveillance,antibiotic resistance of uropathogens of hospitalized patients over a period of 18 months.Methods:Urine samples from wards and cabins were used for isolating urinary tract infection(UTI)-causing bacteria that were cultured on suitable selective media and identified by biochemical tests;and their antibiograms were ascertained by Kirby-Bauer's disc diffusion method,in each 6-month interval of the study period,using 18 antibiotics of five different classes.Results:From wards and cabins,1 245 samples were collected,from which 996 strains of bacteria belonging to 11 species were isolated,during April 2011 to September2012.Two Gram-positive,Staphylococcus aureus(S.aureus)and Enterococcus faecalis(E.faecalis),and nine Gram-negative bacteria,Acinetobacter baumannii,Citrobactcr sp.,Escherichia coli,Enterobacter aerogenes,Klebsiella pneumoniae.Klebsiella oxytoca,Proteus mirabilis,Proteus vulgaris and Pseudomonas aeruginosa were isolated.Both S.aureus and E.faecalis were vancomycin resistant,and resistant-strains of all pathogens increased in each 6-month period of study.Particularly,all Gram-negatives were resistant to nitrofurantoin and co-trimoxazole,the most preferred antibiotics of empiric therapy for UTI.Conclusions:Antibiograms of 11 UTI-causing bacteria recorded in this study indicated moderately higher numbers of strains resistant to each antibiotic studied,generating the fear of precipitating fervent episodes in public health particularly with bacteria,Acinetobacter baumannii,Escherichia coli,Klebsiella pneumoniae and S.aureus.Moreover,vancomycin resistance in strains of S.aureus and E.faecalis is a matter of concern.
文摘Mechanisms of bacterial resistance to fluoro-quinolones may be grouped intothree principal categories: gene mutations of DNA topoisomerase Ⅱ (GyrA or GyrB), DNA topoisomeraseⅣ ( ParC or ParE), decrease of outer membrane permeation and upregulation of multi-drug effluxpump (active efflux system). Efflux pumps are transport proteins removing toxic substrates(including virtually all classes of clinically relevant antibiotics) from cells to the externalenvironment. These proteins exist in both Gram positive bacteria and Gram negative bacteria as wellas in fungi and mammalian (tumour) cells. It has been reported that alkaloid reserpine and carbonylcyanide m-chlorophenylhydrazone (CCCP) can inhibit NorA multi-drug efflux. In order to explore theuniversality of drug efflux in microorganisms, 85 strains of Acinetobacter baumannii (A. baumannii)were tested using reserpine and CCCP. The quinolone-resistant-determining region (QRDR) of gyrA andparC genes in 35 isolates of A. baumannii were amplified by polymerase chain reaction (PCR) andsequenced by DNA sequencer. The correlation between resistant mutation regularity and bacterial drugefflux were analysed.
基金supported by a from grant Priority Academic Program Development of Jiangsu Higher Education Institutions(PAPD)
文摘BACKGROUND:The Acinetobacter baumannii group,including Acinetobacter baumannii,Acinetobacter genomospecies 3 and 13 TU,is phenotypically indistinguishable and uniformly identified as Acinetobacter baumannii by laboratories of clinical microbiology.This review aimed to demonstrate the differences among them.METHODS:Literatures associated with the Acinetobacter baumannii group were identified and selected from PubMed databases and relevant journals.RESULTS:Acinetobacter genospecies 3 and 13 TU possess a certain proportion in clinical isolates.There were considerable differences in epidemiologic features,clinical manifestations,antimicrobial resistances and therapeutic options among the Acinetobacter baumannii group.Compared with Acinetobacter genomospecies 3 and 13 TU,Acinetobacter baumannii with a higher resistance to antimicrobial agents are easier to be treated inappropriately,and present a worse outcome in patients.CONCLUSION:The Acinetobacter baumannii group comprises three distinct clinical entities,and their clinical value are not equal.
