Clinical Efficacy and Safety Analysis of Tigecycline in the Treatment of Acute Exacerbation of Chronic Obstructive Pulmonary Disease Combined with Multidrug-Resistant Acinetobacter baumannii Infection

Objective:To study the clinical efficacy and safety of tigecycline in the treatment of acute exacerbation of chronic obstructive pulmonary disease(COPD)combined with multidrug-resistant Acinetobacter baumannii infection.Methods:113 patients with acute exacerbation of COPD combined with multidrug-resistant Acinetobacter baumannii infection were recruited between January 2021 and January 2023,and given tigecycline treatment.The total effective rate,lung function indexes,related biochemical index levels,and the incidence rate of adverse reactions were observed after the treatment.Results:After the treatment,100 patients were cured,1 case with apparent effect,2 cases were effective,10 cases were ineffective,and the total effective rate was 91.15%.The post-treatment CRP(21.22±3.35 mg/L),PCT(3.18±1.11 ng/L),CRE(76.36±9.24μmol/L),and ALT(37.76±6.99 U/L)were significantly improved as compared to the pre-treatment(P<0.05).After treatment,10 cases of vomiting(8.85%),13 cases of nausea(11.50%),4 cases of diarrhea(3.53%),1 case of abdominal pain(0.88%),and 2 cases of allergy(1.77%)were observed in 113 patients.Conclusion:Tigecycline therapy for patients with acute exacerbation of COPD combined with multidrug-resistant Acinetobacter baumannii infection not only has significant therapeutic efficacy but also has a high degree of safety.

Bloodstream Infection with Carbapenem-resistant Klebsiella Pneumoniae and Multidrug-resistant Acinetobacter Baumannii:a Case Report

IN the presence of septic shock, every hour in delaying the administration of effective antibiotics is associated with a measurable increase in mortality. This is especially true for neutropenic patients with septic shock. As there is a higher incidence of involving multi-drug resistant pathogens for neutropenic patients, the decision on antibiotics regime remains a challenge for physicians.2 Immunosuppression and previous antibacterial use are factors that promote the spread of multi-drug resistant pathogens, and the possibility of co-existing multi-drug resistant pathogens should be suspected when treating patients with these risk factors who developed refractory shock. Here we present a case with neutropenic fever and refractory shock whose blood culture yielded multi-drug resistant Acinetobacter baumannii and carbapenem- resistant Klebsiella pneumoniae.

Postoperative multidrug-resistant Acinetobacter baumannii meningitis successfully treated with intravenous doxycycline and intraventricular gentamicin: A case report

BACKGROUND Multidrug-resistant Acinetobacter baumannii(MDRAB) has emerged as an increasingly important pathogen that causes nosocomial meningitis. However,MDRAB-associated nosocomial meningitis is rarely reported in children.CASE SUMMARY We report the case of a 1-year-old girl with a choroid plexus papilloma, who developed postoperative nosocomial meningitis due to MDRAB. The bacterial strain was sensitive only to tigecycline and colistin, and showed varying degrees of resistance to penicillin, amikacin, ceftriaxone, cefixime, cefotaxime,ciprofloxacin, levofloxacin, gentamicin, meropenem, imipenem, and tobramycin.She was cured with intravenous doxycycline and intraventricular gentamicin treatment.CONCLUSION Doxycycline and gentamicin were shown to be effective and safe in the treatment of a pediatric case of MDRAB meningitis.

Ventilator-associated pneumonia(VAP)and pleural empyema caused by multidrug-resistant Acinetobacter baumannii in HIV and COVID 19 infected patient:A case report

We analyzed the case of a 49-year-old woman with HIV infection off-therapy with poor viro-immunological compensation,not vaccinated for SARS-COV-2,hospitalized for lobar pneumonia and severe COVID19-related respiratory failure in intensive care unit(ICU).The hospitalization was complicated by bacteraemic ventilator-associated pneumonia(VAP)caused by multidrug-resistant Acinetobacter baumannii(MDR-AB)isolated on pleural fluid culture,treated with colistin and cefiderocol for about 3 weeks.The molecular research of MDR-AB on transtracheal aspirate was negative following this therapy.The aim is to show the safety,efficacy and tolerability of colistin-based combination therapy with cefiderocol for Acinetobacter baumannii infection in HIV-infected patient.

中药在控制耐药菌Acinetobacter baumannii繁殖中的研究进展

鲍曼不动杆菌存在多重耐药性,感染后可选择抗菌药物有限,病死率高,抗鲍曼不动杆菌感染是目前临床研究领域的重点和难点。部分中药表现出抑制鲍曼不动杆菌生长的作用,但是其抗菌机制尚不清楚。基于此,本文系统综述了近年来中草药在控制鲍曼不动杆菌感染方面的研究进展,以期为中药抗菌药物的研发提供依据。

Epidemiology of carbapenem-resistant Acinetobacter baumannii colonization in neonatal intensive care units:A systematic review and meta-analysis

BACKGROUND The rising prevalence of carbapenem-resistant Acinetobacter baumannii(CRAB)in neonatal intensive care units(NICUs)represents an escalating challenge in healthcare settings,particularly in managing hospital-acquired infections(HAIs).Studies across various World Health Organization regions have documented a significant incidence of CRAB-related HAIs,with rates as high as 41.7 cases per 1000 patients in ICUs,accounting for 13.6%of all HAIs.These infections pose a doubled mortality risk compared to infections with carbapenem-susceptible Acinetobacter baumannii.A particularly concerning aspect of CRAB colonization is its asymptomatic nature,enabling its transmission through healthcare workers(HCWs)or the NICU environment to vulnerable neonates with developing immune systems.AIM To explore the prevalence of CRAB colonization in NICUs,focusing on neonates,healthcare workers,and the environmental samples,to enhance epidemiological understanding and inform targeted interventions.METHODS We conducted according to PRISMA 2020 checklist guidelines,a comprehensive literature search across multiple databases including MEDLINE(Ovid),EMBASE(Ovid),Global Health(Ovid),Web of Science,and Global Index Me-dicus.Studies were selected based on predetermined criteria,primarily involving neonates,HCWs,and environmental swabs,using culture or molecular methods to detect CRAB colonization.We excluded studies that did not specifically focus on NICUs,were duplicates,or lacked necessary data.The study selection and quality assessment were conducted independently by two reviewers.Data extraction involved collecting comprehensive details about each study.Our statistical analysis used a random-effects model to calculate the pooled prevalence and confidence intervals,stratifying results by regional location.We assessed study heterogeneity using Cochran's Q statistic and I²statistic,with regression tests employed to evaluate potential publication bias.RESULTS We analyzed 737 records from five databases,ultimately including 13 studies from ten countries.For neonates,the pooled prevalence was 4.8%(95%CI:1.1%to 10.5%)with the highest rates observed in South-East Asia(10.5%;95%CI:2.4%to 23.3%).Among HCWs,a single Indian study reported a 3.3%prevalence.Environmental samples showed a prevalence of 2.3%(95%CI:0%to 9.3%),with the highest rates in South-East Asia(10%;95%CI:4.2%to 17.7%).Significant heterogeneity was found across studies,and no publication bias was detected.CONCLUSION This systematic review highlights a significant prevalence of CRAB colonization in neonates across various regions,particularly in South-East Asia,contrasting with lower rates in high-income countries.The study reveals a gap in research on HCWs colonization,with only a single study from India reporting moderate prevalence.Environmental samples indicate moderate levels of CRAB contamination,again higher in South-East Asia.These findings underscore the need for more extensive and focused research on CRAB colonization in NICUs,including exploring the roles of HCWs and the environment in transmission,understanding antimicrobial resistance patterns,and developing effective prevention measures.

Dissemination of carbapenem-non-susceptible Acinetobacter baumannii isolates collected from educational hospitals in Qazvin province of Iran

Background:Acinetobacter baumannii(A.baumannii)is known as an opportunistic pathogen related to health-care-associated infection that has a high antibiotic resistance potential,notably against carbapenems that are widely used to combat A.baumannii infections.This study aimed to detect oxacillin-hydrolyzing(OXA)carbapenemases and metallo-β-lactamases(MBL)among carbapenem-resistant A.baumannii isolated strains and to determine their clonal relationship by repetitive extragenic palindromic PCR(rep-PCR).Methods:In the present study,a total of 211 non-repetitive isolates of A.baumannii were collected from Qazvin educational hospitals(2016–2017).The disk diffusion method was used to investigate the antibiotic susceptibility of studied strains,followed by the detection of MBL and OXA-type genes using polymerase chain reaction(PCR)and sequencing methods.The rep-PCR method assessed the clonal relationship of carbapenem-non-susceptible A.baumannii isolates.Result:The obtained results showed that 87.2%and 86.7%of isolates were non-susceptible to imipenem and meropenem.The blaOXA-24(93.5%)was the most frequent gene,followed by the blaOXA-23(4.34%),blaIMP-1(1.63%),and blaVIM-1(0.54%).Meanwhile,blaOXA-58 and blaOXA-143 genes were not found.81.5%and 66.1%of isolates contained ISAba1 upstream of the blaOXA-23 and blaOXA-58 genes,respectively.Rep-PCR results revealed the carbapenem non-susceptible isolates belonged to three distinct clones:A 171(81%),B 34(16.1%),and C 6(2.8%).Conclusions:The results indicated a high prevalence of carbapenem-non-susceptible A.baumannii,with the emergence of the blaOXA-24 gene as the most common gene and the notable prevalence of MBL genes.These results revealed the need for appropriate therapeutic and infection control strategies and monitoring susceptibility patterns for controlling A.baumannii infections.

Sources of multidrug-resistant Acinetobacter baumannii and its role in respiratory tract colonization and nosocomial pneumonia in intensive care unit patients

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.

Specific and Selective Bacteriophages in the Fight against Multidrug-resistant Acinetobacter baumannii

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.

Control of multidrug-resistant planktonic Acinetobacter baumannii:biocidal efficacy study by atmospheric-pressure air plasma

In this research,an atmospheric-pressure air plasma is used to inactivate the multidrug-resistant Acinetobacter baumannii in liquid.The efficacy of the air plasma on bacterial deactivation and the cytobiological variations after the plasma treatment are investigated.According to colony forming units,nearly all the bacteria（6-log） are inactivated after 10 min of air plasma treatment.However,7% of the bacteria enter a viable but non-culturable state detected by the resazurin based assay during the same period of plasma exposure.Meanwhile,86% of the bacteria lose their membrane integrity in the light of SYTO 9/PI staining assay.The morphological changes in the cells are examined by scanning electron microscopy and bacteria with morphological changes are rare after plasma exposure in the liquid.The concentrations of the long-living RS,such as H2O2,NO3^- and O3,in liquid induced by plasma treatment are measured,and they increase with plasma treatment time.The changes of the intracellular ROS may be related to cell death,which may be attributed to oxidative stress and other damage effects induced by RS plasma generated in liquid.The rapid and effective bacteria inactivation may stem from the RS in the liquid generated by plasma and air plasmas may become a valuable therapy in the treatment of infected wounds.

Study on Distribution of Acinetobacter baumannii Complex in Dental Hospital Using Multiplex PCR

Purpose: In recent years, multidrug-resistant Acinetobacter baumannii has appeared and caused outbreaks of hospital infections all over the world. Close monitoring of this pathogen and other A. baumanii complex species is considered of critical importance to public health organizations. The reliable identification method able to distinguish A. baumannii from genetically close Acinetobacter species is needed, because these species are unable to be differentiated by phenotypic or biochemical methods. The purpose of the present study was to design species-specific primers in order to identify and detect A. baumanii complex species, and Acinetobacter lwoffii which is frequently detected from the human specimens, and to investigate the distribution of these organisms in dental hospital using a multiplex PCR. Methods: Polymerase chain reaction (PCR) primers were designed based on partial sequences of the 16S ribosomal RNA (16S rRNA) gene and DNA gyrase subunit B (gyrB) of each species of A. baumanii complex species. Swab samples were collected from ten dental spittoon units in dental hospital, and the distribution of A. baumanii complex species was investigated using a multiplex PCR. Results: These primers were able to distinguish each species of A. baumanii complex species clearly. A. baumanii and A. calcoaceticus were detected at 20.0% and 10.0% in ten swab samples, respectively. On the other hand, A. nosocomialis, A. lowffii, and A. pittii were detected from no sample. Conclusion: Our developed one-step multiplex PCR method is accurate, specific, cost-effective, time-saving, and worked without requiring DNA extraction.

Risk Factors Associated with MDR and CR Acinetobacter baumannii Carriage among ICU Patients Hospitalized at MOI Teaching and Referral Hospital, Kenya

Background: Multi-drug resistant and Carbapenem-Resistant Acinetobacter baumannii (CRAB) infections present a significant challenge in hospital ICU settings worldwide and the threat posed is worse in developing countries including Kenya. Despite the limited treatment options, there is inadequate comprehensive data on factors associated with MDR and CR Acinetobacter baumannii carriage among ICU patients hospitalized at hospitals. This study therefore aimed to address this gap and determined risk factors associated with MDR and CR Acinetobacter baumannii carriage among ICU patients hospitalized at MOI Teaching and Referral Hospital, Kenya. Methods: Through cross-sectional study design, a total of 132 ICU admitted patients were purposively enrolled in this study between July 2019 and July 2020. Demographic and risk factors associated with MDR and CR Acinobacter baumannii were collected using structured questionnaire. Descriptive statistics and bivalent analysis were used for data analysis obtained. Level of statistical significance was 95% confidence interval (CI) for all analysis. Results: Bivariable analysis showed that employed participants were 3.4 times more likely to have A. baumannii compared to the unemployed (cOR = 3.38, 95%, CI: 1.09 - 10.43, p = 0.035). Patients who were having high BMI were likely to be infected by A. baumannii compared to those who had normal/low BMI (aOR = 11.2, 95%, CI: 3.57 - 21.11, p = 0.004). Those who were aged ≥ 50 years were 21 times more likely to be carbapenem-resistant Acinetobacter baumannii, COR = 21.0, 95% CI: 1.83 - 240.52, p = 0.011. Those who stayed in ICU for more than 30 days were 16 times more likely to be carbapenem-resistant Acinetobacter baumannii compared to those who had been admitted (COR = 16.0, 95% CI: 1.45 - 176.45, p = 0.019). Conclusion: Increased length of hospital stay, obesity and marital status were the factors found to be significantly associated with A. baumannii infections among ICU admitted patients. On the other hand, gender, age, level of education, occupation, referral status and presence of infection were found to have no significant association with A. baumannii infections among ICU admitted patients. All patients admitted to the intensive care units should be screened for colonization with A. baumannii, owing to the poor treatment outcomes associated with carriage of this multidrug resistant pathogen. Proper infection control in the ICU settings should be upheld to mitigate the spread of A. baumannii in the intensive care units.

High prevalence of multidrug-resistance in Acinetobacter baumannii and dissemination of carbapenemase-encoding genes bla_(OXA-23-like),bla_(OXA-24-like)and bla_(NDM-1) in Algiers hospitals

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.

Clinical Distribution and Drug Resistance of Acinetobacter baumannii in a Hospital from 2019 to 2021

Objective:To analyze the clinical distribution and drug resistance of Acinetobacter baumannii(AB)and provide reference for the treatment of AB infection.Methods:AB isolated from clinical specimens of Huaihua First People’s Hospital from 2019 to 2021 were collected and identified by VITEK 2 Compact,an automated microbial identification and susceptibility testing system,in which drug sensitivity test was also performed.Excel was used for statistical analysis.Results:Among the 1,311 AB strains,81.16%(1,064 strains)were from sputum samples,and the departments with the highest detections rates of AB were neurosurgery(24.33%),intensive care(15.48%)and infectious disease(11.44%).The drug sensitivity test showed that the resistance rate of 1,311 AB strains to compound sulfamethoxazole and amikacin was 28.38%and 20.54%,respectively,and the resistance rate to 10 other kinds of common antibiotics was more than 40%.Conclusion:The 1,311 AB strains isolated were widely distributed in clinical settings and had strong resistance to commonly used antibiotics.Therefore,it is necessary to strengthen the monitoring of pathogens and drug resistance,formulate reasonable and effective infection control measures,and ensure that antibiotics are used in a reasonable manner.

Antimicrobial Susceptibility of Multidrug-Resistant <i>Acinetobacter baumanii</i>in a Teaching Hospital: A Two-Year Observation

Multidrug-resistant (MDR) Acinetobacter baumanii (A. baumanii) caused hospital acquired infection, typically in critical-ill patients with medical devices. This is a retrospective descriptive study on epidemiology and microbiology data to determine the antimicrobial susceptibility pattern of MDR-Acinetobacter baumanii isolates from a teaching hospital in Tangerang, Indonesia from Januari 2013 to December 2014. A total of 84 A. baumanii were collected. Patients suffering from respiratory tract infection had the highest number (41.7%) of A. baumanii isolate. There were 39 (46.6%) patients admitted in critical care. A. baumanii isolates in this study mostly were multidrug-resistant organisms with low susceptibility level to 11 antibiotic tested, 44% - 69% in 2013 and 26% - 67% in 2014. A high susceptibility level was observed to amikacin (80% and 79% in 2013, 2014 consecutively) and trimethoprim-sulfamethoxazole (73% and 72% in 2013, 2014 consecutively). A. baumanii is a hospital acquired pathogen in critically-ill patients. The susceptibility pattern of this study result showed MDR organism. There was a sharp decrease of susceptibility in all antibiotics studied from 2013 to 2014 except amikacin and trimethoprim-sulfamethoxazole.

Acinetobacter baumannii WJ6菌落的生长及其异养硝化-好氧反硝化特性

从活性污泥中分离出一株异养硝化-好氧反硝化菌WJ6,经16S rDNA鉴定该菌株被命名为Acinetobacter baumannii WJ6。菌株WJ6的生长状况与硝化及反硝化程度几乎一致。在以(NH_4)_2SO_4为唯一氮源时,经过24 h培养该菌株的氨氮去除率为95.4%;在分别以硝酸盐和亚硝酸盐作为唯一氮源时,经过32 h培养,硝酸盐氮的去除率达到81.7%,亚硝酸盐氮的去除率达到94.9%,表明该菌株具有良好的异养硝化-好氧反硝化能力。

Antimicrobial resistance in Acinetobacter baumannii : From bench to bedside

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.

Biofilm formation in clinical isolates of nosocomial Acinetobacter baumannii and its relationship with multidrug resistance

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.

Antibiotic resistance and carriage class 1 and 2 integrons in clinical isolates of Acinetobacter baumannii from Tehran,Iran

Objective:To investigate antibiotic resistance and carriage class 1 and 2 integrons in clinical isolates of Acinetobacter baumannii(A.baumannii)from Tehran,Iran.Methods:Antimicrobial susceptibility testing was performed according to the Clinical and Laboratory Standards Institute.The presence of integrons was investigated by PCR using specific primers.Results:Among isolated A.baumannii strains,82%were multidrug resistant,27 samples(54%)were resistant to three or more than three antibiotics and 16 samples(32%)showed resistance to two antibiotics.Integrons were detected from 44 of 50 isolates(88%),with classes 1 and 2 being observed in 42%(21/50)and 82%(41/50)of isolates,respectively.Integron-positive A.baumannii isolates showed higher antibiotic resistance than integron-negative isolates and all showed a multidrug-resistant phenotype.Conclusions:Our findings show that classes 1 and 2 integrons,and especially classes 2 integrons are widely disseminated among A.baumannii strains isolated from Tehran and these structures are playing a major role in the acquisition of multidrug resistance in these strains.So monitoring of drug resistance with investigating carriage class 1 and 2 integrons is very important to plan specific infection control measures due to multidrug resistance A.baumannii in Iran hospitals.

Risk factors and clinical responses of pneumonia patients with colistin-resistant Acinetobacter baumannii-calcoaceticus

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.