二级医院鲍曼不动杆菌感染的临床特征和同源性分析

目的：研究二级医院鲍曼不动杆菌感染患者的临床特征,对耐碳青霉烯鲍曼不动杆菌进行同源性分析,为临床治疗和医院感染控制提供依据。方法收集临床分离的115株非重复性鲍曼不动杆菌,回顾性分析患者的临床资料和细菌药敏资料。采用 Vitek2 Compact 对115株鲍曼不动杆菌进行19种抗菌药物的敏感性检测。采用肠杆菌科基因间一致重复序列聚合酶链技术(ERIC-PCR)对其中的耐碳青霉烯鲍曼不动杆菌进行基因分型和同源性分析。结果115例患者主要集中在 ICU、干部病房和呼吸科病房。患者的平均年龄为(75±16)岁。平均住院时间52.1 d。最常见的合并症为COPD 和糖尿病。72例(62.61%)患者曾接受侵入性操作。86例(74.78%)患者病程中使用过2种及以上的抗生素。48例(41.74%)患者接受机械通气。115株鲍曼不动杆菌对多黏菌素 B 耐药率最低,为0%,其次为替加环素,耐药率7.83%。仅头孢哌酮/舒巴坦、阿米卡星耐药率低于40%,对其他常用抗生素的耐药率均高于50%。对亚胺培南和美罗培南的耐药率分别达56.52%和58.26%。ERIC-PCR 技术将67株耐碳青霉烯鲍曼不动杆菌分为9个基因型。结论二级医院鲍曼不动杆菌感染患者的临床特征为：高龄,住院时间长,合并基础疾病,接受侵入性操作,接受机械通气及使用多种抗生素。对常用的抗生素高度耐药。多重耐药鲍曼不动杆菌及广泛耐药鲍曼不动杆菌存在院内接触传播的现象,因此应该提高医护人员消毒意识,加强耐药性监测及合理使用抗菌药物。     

贵州省2017-2018年非伤寒沙门菌临床分离株耐药及分子分型研究

目的 了解贵州省2017-2018年非伤寒沙门菌(NTS)的血清型分布、耐药情况与脉冲凝胶电泳(PFGE)分子分型特征。方法 对分离自贵州省临床病例的191株非伤寒沙门菌菌株进行生化鉴定、血清型分型,微量肉汤稀释法测定16种抗生素的最小抑菌浓度,PFGE进行分子分型分析。结果 191株非伤寒沙门菌分出18种血清型,鼠伤寒沙门菌(45.5%,87/191)和肠炎沙门菌(29.3%,56/191)为主要血清型。对所测抗生素产生耐药的菌株占96.8%(185/191),对磺胺异恶唑、链霉素、氨苄西林、四环素、多西环素耐药率较高,均超过60.0%。对头孢曲松和环丙沙星耐药率分别为7.9%(15/191)和13.1%(25/191)。多重耐药率为84.3%(161/191),共有69种耐药谱,主要耐药谱型为氨苄西林+链霉素+磺胺异恶唑+萘啶酸和氨苄西林+氯霉素+链霉素+磺胺异恶唑+四环素+多西环素+复方新诺明。87株鼠伤寒沙门菌共分为60种带型,优势型别为JPXX01.GZ0047(12.6%,11/87)。56株肠炎沙门菌共分为21种带型,优势型别为JEGX01.GZ0005(23.3%,13/56)。结论 贵州省NTS主要血清型为鼠伤寒沙门菌和肠炎沙门菌,多重耐药现象严重,PFGE带型总体呈多样性,部分带型与耐药表型有一定的关联性。     

Aerosolized colistin as adjunctive treatment of ventilator-associated pneumonia due to multidrug-resistant Gram-negative bacteria: a prospective study

BACKGROUND: Ventilator-associated pneumonia (VAP) remains the leading cause of death in patients with intensive care unit (ICU) acquired infections associated with an attributable mortality around 30%. Increasing antimicrobial resistance in patients with VAP challenges intensivists to search for alternative therapeutic options. There is scarcity of data in the literature concerning the administration of aerosolized colistin in critically ill patients with VAP due to multidrug-resistant (MDR) Gram-negative pathogens. METHODS: To assess the safety and effectiveness of aerosolized colistin as an adjunctive to the intravenous antimicrobial therapy for the treatment of VAP due to MDR Gram-negative pathogens, we prospectively examined all patients, who received inhaled colistin. RESULTS: Sixty critically ill patients with a mean APACHE II score 16.7, received aerosolized colistin for the treatment of VAP due to MDR pathogens [Acinetobacter baumannii (37/60 cases), Pseudomonas aeruginosa (12/60 cases) and Klebsiella pneumoniae strains (11/60 cases)]. Half of the isolated pathogens were susceptible only to colistin. Mean (+/-SD) daily dosage of aerosolized colistin was 2.2 (+/-0.7) million international units (IU). All patients received 2946 inhalations of colistin and the mean duration of administration was 16.4 days. Fifty-seven patients received concomitant intravenous treatment with colistin or other antimicrobial agents. Bacteriological and clinical response of VAP was observed in 50/60 (83.3%) patients. No adverse effects related to inhaled colistin were recorded. All cause hospital mortality was 25% while mortality attributable to VAP was 16.7%. CONCLUSIONS: Aerosolized colistin may be considered as adjunctive to intravenous treatment in patients with VAP due to MDR Gram-negative bacteria susceptible to colistin in critically ill patients. Although colistin is safe and effective, the best route of administration remains unclear. In addition, controlled comparative studies are needed to establish its effectiveness and safety.     

Nosocomial bloodstream infections caused by Acinetobacter species in United States hospitals: clinical features, molecular epidemiology, and antimicrobial susceptibility.

We examined the clinical and epidemiological features of nosocomial bloodstream infections (BSIs) caused by Acinetobacter species and observed from 1 March 1995 through 28 February 1998 at 49 United States hospitals (SCOPE National Surveillance Program). Acinetobacter species were found in 24 hospitals (49%) and accounted for 1.5% of all nosocomial BSIs reported. One hundred twenty-nine isolates were identified either as A. baumannii (n=111) or other Acinetobacter species (n=18). Patients with A. baumannii BSI, compared with patients with nosocomial BSI caused by other gram-negative pathogens, were more frequently observed in the intensive care unit (69% vs. 47%, respectively; P<.001; odds ratio [OR] 2.4; 95% confidence interval [CI] 1.6-3.7) and were more frequently receiving mechanical ventilation (58% vs. 30%, respectively; P<.001; OR 3.2; 95% CI 2.1-4.8). Crude mortality in patients with A. baumannii BSI was 32%. Molecular relatedness of strains was studied by use of polymerase chain reaction-based fingerprinting. Clonal spread of a single strain occurred in 5 hospitals. Interhospital spread of epidemic A. baumannii strains was not observed. The most active antimicrobial agents against A. baumannii (90% minimum inhibitory concentration values) were imipenem (1 mg/L; 100% of isolates susceptible), amikacin (8 mg/L; 96%), tobramycin (4 mg/L; 92%), and doxycycline (4 mg/L; 91%). Thirty percent of isolates were resistant to > or =4 classes of antimicrobials and were considered to be multidrug resistant.     

Antibiotic susceptibility, serotype distribution and vaccine coverage of nasopharyngeal and oropharyngeal Streptococcus pneumoniae in a day-care centre in St. Petersburg, Russia

The objectives were to study serotypes and antibiotic susceptibility of Streptococcus pneumoniae carried by healthy children attending a day-care centre in St. Petersburg. S. pneumoniae colonization was investigated in 125 children aged 16-70 months. Antibiotic susceptibility was determined by E-test and disk diffusion. 83 S. pneumoniae cases were isolated in 75/125 (60%) children: 36/75 (48%) in the nasopharynx, 12/75 (16%) in the oropharynx and 27/75 (36%) in both. Carriage rates were 100%, 68%, 72%, 46% and 54% in children aged 12-23, 24-35, 36-47, 48-59 and >or=60 months, respectively. 97.6% of isolates were susceptible to penicillin. 61.4%, 32.5%, 19.3%, 16.7% and 6% isolates were non-susceptible to trimethoprim/sulfamethoxazole, tetracycline, clindamycin, erythromycin and chloramphenicol, respectively. 20.5% of isolates were multidrug resistant (MDR). 45% of isolates were of serotypes included in the 7-valent pneumococcal conjugate vaccine (7V-PCV); 64.9%, 56.8%, 32.4% and 27% of 7V-PCV serotypes were resistant to trimethoprim/sulfamethoxazole, tetracycline, clindamycin and erythromycin, respectively. The respective figures for MDR isolates were 100%, 94.1%, 70.6% and 76.5%; 76.5% of all MDR isolates were covered by 7V-PCV. In conclusion: 1) resistance to trimethoprim/sulfamethoxazole and tetracycline was high; 2) resistance to macrolides was higher than in other Russian regions; 3) 7V-PCV coverage was modest, but the vaccine may potentially reduce MDR-S. pneumoniae.     

High prevalence of metallo-beta-lactamase-producing acinetobacter baumannii in a teaching hospital in Tabriz, Iran

Metallo-beta-lactamase (MBL)-producing Acinetobacter baumannii has become a growing therapeutic concern worldwide. The aims of this study were to evaluate the antimicrobial susceptibility of A. baumannii isolates and to determine the prevalence of MBL genes among carbapenem non-susceptible isolates. During a period of 16 months (March 2008-June 2009), 100 isolates of A. baumannii were collected from different clinical specimens of inpatients admitted to the largest teaching hospital in the northwest of Iran. All isolates were tested for antimicrobial susceptibility by Kirby-Bauer disk diffusion method. Carbapenem non-susceptible isolates were further screened for production of MBL by Etest and were then subjected to PCR for detection of MBL genes of types bla(IMP) and bla(VIM). Among 63 carbapenem (imipenem and meropenem) non-susceptible isolates of A. baumannii, 31 (49%) were found to be MBL producers. Of 31 MBL-producing isolates, 19 (61%) carried the bla(IMP) gene and 9 (29%) carried the bla(VIM) gene. All MBL-producing isolates were multidrug resistant. This is the first report of IMP and VIM types among MBL-producing A. baumannii in Iran.     

Identification of acinetobacter species isolated from human infections based on a new classification by Bouvet and Grimont

The genus Acinetobacter was recently re-classified by Bouvet and Grimont who described four new species, A. baumannii, A. haemolyticus, A. johnsonii and A. junii, and five unnamed genospecies, with a re-definition of A. calcoaceticus and A. lwoffii which appeared in the Approved Lists of Bacterial Names, 1980. One hundred and twenty-eight clinical isolates previously identified as Acinetobacter were retrieved from storage and re-characterized by using a system based on the grouping reactions described by Bouvet and Grimont. Of these 86.7%, 2.3%, and 1.6% were identified as A. baumannii, A. junii and Acinetobacter genospecies 11, respectively, and the remaining 9.4% of the cultures were unidentified. None of the cultures identified as A. calcoaceticus and A. lwoffii was included in the 128 cultures.     

Antimicrobial susceptibility patterns and distribution of blaOXA genes among Acinetobacter spp. Isolated from patients at Tehran hospitals

Multiple drug-resistant strains of Acinetobacter have created therapeutic problems worldwide. This study was conducted to determine the antimicrobial susceptibility patterns and prevalence of bla(OXA-type) carbapenemases among isolates of Acinetobacter spp. obtained from Iranian patients. Here, 128 Acinetobacter isolates were identified at the species level, and their susceptibilities to different antibiotics were determined using disk agar diffusion testing. Isolates were then subjected to multiplex-PCR targeting bla(OXA) genes. More than 50% of the isolates showed multidrug resistance to different antibiotics. The rates of susceptibility to imipenem, meropenem, piperacillin-tazobactam, and amikacin were 50.7, 50, 42.1, and 38.2%, respectively. The MICs of carbapenems for the resistant isolates ranged from 64 to > or = 256 microg/ml. All strains of Acinetobacter baumannii possessed a bla(OXA-51-like) gene. The co-existence of bla(OXA-51-like)/bla(OXA-23-like) and bla(OXA-51-like)/bla(OXA-24-like) was detected in 25% (n=32) and 17.9% (n=23) of the isolates, respectively. Over 70% of carbapenem-resistant strains contained at least two genes encoding OXA-type carbapenemase. Resistance to carbapenems in the population of Acinetobacter strains in Iran is high, with the majority of isolates showing multidrug resistance. A wide diversity of OXA genes exists among the strains of A. baumannii in Iran. Detection of bla(OXA-51-like) can be used as a simple and reliable method to differentiate A. baumannii strains from other species.     

Antimicrobial resistance of Gram-negative bacilli isolates from inpatients and outpatients at Yaounde Central Hospital, Cameroon.

OBJECTIVE: To determine and compare antimicrobial susceptibility patterns of pathogenic bacteria from inpatients and outpatients at a university teaching hospital in Yaounde, Cameroon. METHODS: Gram-negative bacilli isolates (n = 522), obtained from a wide range of clinical specimens (urine, pus and blood) from inpatients and outpatients at Yaounde Central Hospital between March 1995 and April 1998, were evaluated for resistance to antibiotics (amoxicillin, amoxicillin/clavulanate, piperacillin, cefazolin, cefoxitin, cefotaxime, ceftazidime, aztreonam, imipenem, gentamicin, tobramicin, ofloxacin and trimethoprim/sulfamethoxazole). RESULTS: Of the 522 isolates recorded, 80.3% were Enterobacteriaceae. A high incidence of resistance to amoxicillin (85%), piperacillin (75%) and trimethoprim/sulfamethoxazole (71%) was observed. The proportion of antimicrobial-resistant isolates from inpatients was significantly higher than that from outpatients (P < 0.05), except for piperacillin, tobramicin and trimethoprim/sulfamethoxazole. The combinations of antimicrobial and organism showed that the percentage of ceftazidime-resistant Pseudomonas aeruginosa and ceftazidime-resistant Enterobacter cloacae were 26.8% and 24% respectively. The rate of antimicrobial resistance in isolates from inpatients was not significantly higher than that in isolates from outpatients for all the antimicrobial/organism combinations, except for ceftazidime-resistant Escherichia coli, which was exclusively found in isolates from inpatients. Among Enterobacteriaceae, high and low level penicillinase (mostly in E. coli (13.6% and 11% respectively) and Klebsiella spp. (9% and 8% respectively) were the most important beta-lactam resistance phenotypes (31.2% and 23.6%, respectively). Wild type (exclusively observed in E. coli, Proteus mirabilis and Salmonella spp.) and low level penicillinase were higher in outpatient than inpatient isolates (wild type--17.9% vs 10.8% and low level penicillinase--29.4% vs 20.5%, respectively; P < 0.05). However, extended spectrum beta-lactamase strains (Klebsiella spp. (3.5%), E. coli (2.6%), Citrobacter spp. (0.7%), Enterobacter spp. (0.4%) and P. mirabilis (0.2%)) were exclusively recovered from inpatients. Penicillinase and high level cephalosporinase resistance phenotypes were frequently observed in non-fermenter Gram-negative bacilli (46.6% and 29.1% respectively). However, there were no significant differences in penicillinase and cephalosporinase resistance between inpatient and outpatient isolates. CONCLUSION: As the incidence of antimicrobial resistance is substantially higher in isolates from inpatient than outpatient pathogens, more resources should be allocated within the hospital to encourage good antibiotic practices and good hospital hygiene.     

Prevalence of antibiotic resistance among Acinetobacter baumannii isolates from Aleppo, Syria

This study describes and analyzes Acinetobacter baumannii antibiotic susceptibly profile in Aleppo, Syria, thus providing vital information for guiding treatment of A baumannii infections. Two hundred sixty nonrepetitive A baumannii isolates were studied over 3.5 years. Resistance rates are at the higher end of globally reported levels. Newer cephalosporins and β-lactamase-resistant agents are becoming practically ineffective. Better activity is limited to carbapenems and colistin, which elicited the highest susceptibility levels.     

鲍曼不动杆菌临床株中可移动遗传元件ISCR1的作用

目的了解鲍曼不动杆菌临床株中新型可移动遗传元件ISCR1的携带情况及其下游基因环境,探讨鲍曼不动杆菌耐药播散机理。方法收集多重耐药鲍曼不动杆菌临床株34株和敏感株21株,PCR扩增ISCR1基因及其下游的基因环境,扩增产物测序分析。结果 34株多重耐药鲍曼不动杆菌临床株中,携带ISCR1基因14株,其中11株ISCR1阳性多重耐药株,在ISCR1基因下游携带氨基糖甙类耐药基因armA基因;21株敏感株中,ISCR1基因扩增结果均为阴性。结论 ISCR1元件可能参与了armA耐药基因的水平播散。     

348株下呼吸道鲍曼不动杆菌耐药性及变迁分析

目的了解鲍曼不动杆菌及对碳青酶烯类抗生素耐药的鲍曼不动杆菌耐药性及变迁情况。方法采用纸片扩散法对2008～2010年从下呼吸道分离出的348株鲍曼不动杆菌进行药敏试验。结果鲍曼不动杆菌对头孢哌酮/舒巴坦(14.4%)耐药性最低,其次是碳青酶烯类药物亚胺培南(16.1%)和美罗培南(18.4%);对常用抗菌药物的耐药性均呈上升趋势。56株亚胺培南耐药鲍曼不动杆菌中,耐药率最高的是哌拉西林(100%),其次是替卡西林/克拉维酸、氨曲南和庆大霉素;耐药率最低的是米诺环素,其次为头孢哌酮/舒巴坦和环丙沙星。结论鲍曼不动杆菌耐药严重,加强耐药性监测,应根据药敏结果合理使用抗生素,以保护有限的抗生素资源。     

In vitro activity of colistin or sulbactam in combination with fosfomycin or imipenem against clinical isolates of carbapenem-resistant Acinetobacter baumannii producing OXA-23 carbapenemases

This study investigated the in vitro activity of colistin or sulbactam in combination with fosfomycin or imipenem against eight strains of carbapenem-resistant A. baumannii (CRAB). The eight CRAB clinical isolates were collected from hospitalized patients admitted to Songklanagarind Hospital in southern Thailand during January-December 2008. The isolates were divided into 4 different patterns of clonal relationships using the Repetitive Extragenic Palindromic-Polymerase Chain Reaction method (REP-PCR). The in vitro activity of combination antibacterial agents against theses isolates were determined by chequerboard and time-kill methods. All isolates producing OXA-23 carbapenemases were universally susceptible to colistin but intermittently susceptible to other antimicrobial agents. A chequerboard assay showed the synergistic effects of sulbactam plus fosfomycin and colistin plus fosfomycin in 75% and 12.5% of isolates, respectively. Sulbactam at a concentration of 1 x MIC plus fosfomycin at 1 x MIC or at 1/4 x MIC showed synergism in 75% and 37.5% of clinical isolates, respectively. Bactericidal activity was observed for up to 12 hours of incubation. There was no synergism between colistin and sulbactam, sulbactam and imipenem, and colistin and imipenem, against the tested isolates. Combined use of sulbactam and fosfomycin may provide an alternative therapeutic option for CRAB infections.     

部分非鲍曼不动杆菌耐药性及相关基因分析

目的了解目前非鲍曼不动杆菌临床分离株的耐药现状及耐药基因携带情况。方法随机抽取100株不动杆菌临床分离株,采用分子生物学方法筛选非鲍曼不动杆菌,用E-test方法检测非鲍曼不动杆菌对12种抗生素的耐药性,用PCR方法检测16种相关耐药基因的分布。结果共筛选出17株非鲍曼不动杆菌,7株为多重耐药(41.2%),其中对头孢噻肟的耐药率为100%,对氯霉素、哌拉西林、氨苄西林和氨曲南的耐药率分别为76.5%、76.5%、64.7%和52.9%,对多粘菌素B普遍敏感;检出6种耐药基因分别为ampC、blaTEM、blaPER-1、blaOXA-23-like、blaOXA-58和Int1。结论携带超广谱β-内酰胺酶(ESBLs)基因和blaOXA-23-like基因为非鲍曼不动杆菌对β-内酰胺类和碳青霉烯类抗生素耐药的主要原因。非鲍曼不动杆菌的耐药形势严峻,应加强监测。     

Genotypic analysis of Acinetobacter bloodstream infection isolates in a Turkish university hospital

Acinetobacter baumannii is a significant pathogen of bloodstream infections in hospital patients that frequently causes single clone outbreaks. We aimed to evaluate the genetic relatedness and antimicrobial susceptibility of Acinetobacter spp. bloodstream isolates, in order to obtain insight into their cross-transmission. This prospective study was conducted at the Erciyes University Hospital. During a 1-y period, all patients with nosocomial BSI caused by Acinetobacter spp. were included in the study. All data with regard to the patients, underlying diseases and risk factors for BSI and the severity of disease were collected. Blood culture isolates of Acinetobacter spp. were identified according to their morphology and biochemical reactions. The antimicrobial susceptibility was determined using the Kirby-Bauer disk diffusion test according to the NCCLS; the genetic relatedness of isolates was determined by RAPD-PCR analysis and pulsed-field gel electrophoresis (PFGE). 41 patients acquired a nosocomial bloodstream infection caused by A. baumanii during this period. 88% of these infections (36 of 41) occurred while the patients were treated in the intensive care unit. Nearly 80% of the isolates belonged to 3 genotypes, suggesting cross-transmission in ICU settings where infection control practices are poor. All Acinetobacter isolates were multidrug-resistant and the crude mortality of patients infected with A. baumanii was 80.5%. We concluded that the genetic relatedness of Acinetobacter spp. causing BSI was very high, indicating cross-transmission within the ICU setting. Essential components of an infection control programme to prevent nosocomial transmission of A. baumannii are early detection of colonized patients, followed by strict attention to standard precautions and contact isolation.     

High-dose ampicillin-sulbactam as an alternative treatment of late-onset VAP from multidrug-resistant Acinetobacter baumannii

The increased incidence of multidrug-resistant (MDR) Acinetobacter baumannii ventilator-associated pneumonia in critically ill patients poses a severe therapeutic problem. The aim of this study was to evaluate the efficacy and safety of 2 high-dose treatment regimens of ampicillin-sulbactam (A/S) for MDR Acinetobacter baumannii VAP. We undertook a randomized, prospective trial of critically ill patents with (MDR) Acinetobacter baumannii VAP. Patients were randomly assigned to 1 of 2 treatment regimens of A/S (at a rate 2:1 every 8 h): 1) group A, 18/9 g daily dose (n = 14); and 2) group B, 24/12 g daily dose (n = 13). The duration of therapy was 8+/-2 d for both groups. A total of 27 patients were enrolled in the study. Clinical improvement was seen in 66.7% of the study population in 9/14 (64.3%) of group A patients and 9/13 (69.2%) of group B patients, respectively. Bacteriological success was achieved in 77.8% of the study population (12/14, 85.7% of group A) and in 9/13 (69.2%) of group B patients. The 14-d mortality rate was 25.9% and the all cause 30-d mortality was 48.1%. Both mortality rates did not differ significantly between the 2 groups. No major adverse reactions were recorded. We concluded that clinical and bacteriological results of the study support the use of high-dose regimen of ampicillin-sulbactam for MDR Acinetobacter baumannii VAP.     

Cure of multidrug-resistant Acinetobacter baumannii bacteraemia with continuous intravenous infusion of colistin

Continuous intravenous colistin (2,000,000 units per 24 h) was administered in a 41-y-old patient with Acinetobacter baumannii bacteraemia, which led to the cure of the infection. The isolated microorganism was a multi-resistant strain (it was sensitive only to colistin). In addition, the patient had developed allergic reactions to previously administered antimicrobial agents of several classes during his hospitalization. Continuous intravenous infusion of colistin proved to be a salvage regimen, which led to cure of a bacteraemia due to a multi-resistant isolate, without showing any allergic cross-reactivity with other antibiotics.     

Class 1 integrons and resistance gene cassettes among multidrug resistant Salmonella serovars isolated from slaughter animals and foods of animal origin in Ethiopia

The present study was undertaken to identify and characterize integrons and integrated resistance gene cassettes among multidrug resistant (MDR) Salmonella isolates from slaughter animals and food products of animal origin in Ethiopia. A total of 98 epidemiologically unrelated Salmonella isolates comprising 13 serovars were characterized using serotyping, phage typing, antimicrobial resistance testing and the pulsed-field gel electrophoresis (PFGE) method. Integron-PCR was used to detect the presence of class 1 and class 2 integrons in the MDR strains. The associated individual resistance gene cassettes were identified using specific PCRs and DNA sequencing. The location of the integrons was determined by Southern blot hybridization analysis. Among the Salmonella serovars, a high level of antimicrobial resistance was found to streptomycin (82.6%), tetracycline (75.5%), sulfamethoxazole (60.2%), spectinomycin (53.1%), ampicillin (42.8%), nalidixic acid (34.7%), nitrofurantoin (30.6%), trimethoprim (27.5%), gentamicin (20.4%) and ciprofloxacin (19.4%). Class 1 integrons were detected in 53.1% of the MDR isolates comprising serovars Anatum, Braenderup, Kentucky, Saintpaul and Typhimurium. Of the class 1 integron positive isolates 61.5% harboured the integron-associated gene cassettes: aadA2, aadA2+bla(PSE-1), dfrA1-aadA1 and dfrA12-orf-aadA2 (amplicon sizes 1000 bp, 1000+1200 bp, 1600 bp and 1900 bp, respectively). The chromosomally located aadA2 and aadA2+bla(PSE-1) resistance gene cassettes occurred exclusively in S. Typhimurium DT104 isolates, the other cassettes were found on large plasmids in several serovars. An aacCA5-aadA7 gene cassette array (amplicon size 1600 bp) was exclusively found in all MDR S. Kentucky strains of R type Str/SpeSmxGenNalAmpTetCipCef and this integron was shown to be chromosomally located. Results of the present study indicate that class 1 integrons carrying gene cassettes, which confer resistance to different classes of antimicrobials such as aminoglycosides, beta-lactams and trimethoprim are widespread among the MDR Salmonella serovars isolated from slaughter animals and food products of animal origin in Ethiopia indicating the important role of these genetic elements in the dissemination of multidrug resistance.