Susceptibility patterns of Enterococcus spp. isolated in Poland during 1996

Susceptibility of Enterococcus spp. isolated from various clinical specimens to different antimicrobial agents was evaluated. Of the 346 enterococcal isolates obtained from four regional Polish hospitals during 6 months of 1996, 261 (75.4%) were identified as Enterococcus faecalis, 75 (21.7%) as Enterococcus faecium and ten (2.9%) as other enterococcal species. High-level resistance to gentamicin was expressed by 33.4% of E. faecalis and 86.5% of E. faecium strains and corresponding streptomycin resistance by 43.9 and 82.4%, respectively. Over 80% of E. faecium isolates were resistant to ampicillin. None of the isolates was resistant to teicoplanin, however 7.9% of E. faecalis and 1.4% of E. faecium strains were moderately susceptible to vancomycin.     

Safety and potential risks of enterococci isolated from traditional fermented capers

A collection of 17 enterococci isolates obtained from fermentations of capers (the fruits of Capparis sp.) were investigated for incidence of known virulence determinants, antibiotic resistance and production of biogenic amines. Molecular identification revealed the presence of Enterococcus faecium (nine isolates), Enterococcus faecalis (4), E. avium (3) and Enterococcus casseliflavus/flavescens (1). Alpha-haemolytic activity was detected in two E. avium and one E. faecalis isolates, and beta-haemolytic activity was detected in E. casseliflavus/flavescens. The haemolytic component cylB was detected by PCR amplification in three non-haemolytic isolates and in E. casseliflavus/flavescens. The collagen adhesin ace gene and the endocarditis associated antigen gene efaA_fm were detected in two isolates each. Genes encoding sex pheromone precursors (cpd, cob, ccf) were detected in E. faecalis and E. casseliflavus/flavescens. Other presumed virulence genes (agg, gelE, cylM, cylA and efaA_fs) were not detected. All isolates were resistant to rifampicin, erythromycin and ciprofloxacin, and some were also resistant to quinupristin/dalfopristin, tetracycline, levofloxacin, gentamicin and streptomycin. Vancomycin resistance was not detected. Tyrosine decarboxylation was detected in all E. faecium isolates. Given the high resistance of enterococci to environmental conditions, and their implication in opportunistic infections, the incidence of potential virulent enterococci in foods (especially those of a higher risk-like home-made foods) should be carefully studied.     

Clinical relevance of a European collaborative study on comparative susceptibility of Gram-positive clinical isolates to teicoplanin and vancomycin

Seventy laboratories in nine European countries (Belgium, France, Germany, Italy, The Netherlands, Portugal, Spain, Switzerland and the UK) each collected 100 consecutive Gram-positive bacterial pathogens during 1995. MICs were determined by a co-ordinating laboratory in each country using an agar incorporation method with Mueller Hinton medium (NCCLS). Quality control was ensured by distribution of five test strains to the co-ordinating laboratories. A total of 7078 isolates was collected: 2885 Staphylococcus aureus, 1706 enterococci, 1480 coagulase-negative staphylococci (CNS), 932 Streptococcus spp. (including 289 strains of S. pneumoniae) and 75 miscellaneous species. Of these, the country coordinators successfully re-tested 6824 isolates. Using NCCLS interpretive criteria, overall 39 isolates (including 28 strains of enterococci) were teicoplanin-resistant (0.57%) and 38 (mostly CNS; 0.56%) were intermediate, whilst 32 isolates (including 30 strains of enterococci) were resistant to vancomycin (0.47%) and 7 (all enterococci; 0.10%) were intermediate. The overall resistance rate was ≤0.5%. The two glycopeptides were essentially active against the major pathogens encountered in the survey. The only real difference with clinical implications from previously reported susceptibility data is the emergence and spread of resistance in enterococci, particularly in E. faecium. Resistance was highest in SSTI, UTI, bloodstream and GI infections; no resistance was encountered in RTI, gynaecological infections or central nervous system infections. This resistance was also geographically diverse: Resistance to vancomycin in E. faecalis was present only in France, Germany, Italy, Portugal and Spain (Italy and Spain only for teicoplanin), whilst resistance to teicoplanin and vancomycin in E. faecium was present in all countries except Spain. Eight isolates (0.5% of all enterococci) were vancomycin-resistant but teicoplanin-susceptible, exhibiting the vanB phenotype. These were four strains of E. faecalis and four strains of E. faecium. Whilst isolates of S. haemolyticus had higher MIC of teicoplanin than other CNS, and were more susceptible to vancomycin, overall resistance to teicoplanin was low (3.3% in S. haemolyticus; 0.6% in CNS). S. haemolyticus was a relatively rare pathogen, accounting for 6.3% of all CNS isolates, and 1.4% of all Gram-positives collected. The results of this survey show that, despite occasional nosocomial problems (e.g. with enterococci and S. haemolyticus), teicoplanin or vancomycin remain adequate therapy for infections caused by Gram-positive pathogens in the 1990s.     

Importance of amino acid alterations and expression of penicillin-binding protein 5 to ampicillin resistance of Enterococcus faecium in Taiwan

The importance of the amino acid sequence in the C-terminal domain of penicillin-binding protein 5 (PBP5) and the levels of PBP5 expression to ampicillin resistance of Taiwan clinical isolates of Enterococcus faecium were studied. Sequence data revealed the existence of 12 amino acid sequence variants within the C-terminal domain of PBP5 in the 33 tested isolates (ampicillin minimum inhibitory concentrations (MICs) 1 mg/L to >256 mg/L). Western blot analyses of the levels of PBP5 showed that, with few exceptions, lower amounts of PBP5 were present in the susceptible strains than in the resistant strains. More importantly, a significant correlation (P = 0.004, Fisher's exact test) between the expression of PBP5 and ampicillin resistance was detected. Point mutations in PBP5, including addition of aspartic acid or serine after position 466 and change of methionine to alanine or threonine at position 485, alanine or isoleucine to threonine at position 499 and glutamate to valine at position 629, were found to be significantly associated with ampicillin resistance. A significant correlation was obtained for the combined mutation (alleles 10 and 11), suggesting that combined mutation of PBP5 can be a marker for ampicillin resistance of E. faecium.     

Influence of adjunctive interferon-gamma on treatment of gentamicin- and vancomycin-resistant Enterococcus faecalis infection in mice.

Increasing antibiotic resistance and the development of multidrug-resistance in the enterococci has complicated the treatment of serious enterococcal infections. It has been demonstrated in vitro that interferon-gamma (IFN-γ) significantly augments the activities of gentamicin and vancomycin against Enterococcus faecalis resistant to these antibiotics. The present study was aimed at determining whether this beneficial effect of IFN-γ on antienterococcal antibiotic activity can be validated in vivo. Following intraperitoneal inoculation in mice with a gentamicin- and vancomycin-resistant E. faecalis clinical isolate, the animals received IFN-γ, antibiotic or a combination of both agents, subcutaneously, at determined dosing regimens. Treatment with IFN-γ alone significantly improved survival of infected animals in a dose-dependent manner. High dose IFN-γ was not beneficial and the level of enterococcal infectious burden influenced the effectiveness of the cytokine. The addition of IFN-γ to therapy with gentamicin or vancomycin, or a combination of both antibiotics was associated with a marked increase in survival of infected non-neutropenic mice compared to treatments with the agents alone. However, the same treatments made in infected neutropenic mice did not show an enhancement effect by IFN-γ after a combination therapy with antibiotics. In a study to examine pharmacokinetic interactions, concurrent administration with IFN-γ significantly modified the disposition of gentamicin but not that of vancomycin. The results of this study suggest that the use of IFN-γ in combination with vancomycin or gentamicin is a new treatment option that might improve the outcome of therapy of multidrug-resistant E. faecalis infections.     

Risk factors in enterococci isolated from foods in Morocco: Determination of antimicrobial resistance and incidence of virulence traits

A collection of enterococci isolated from meat, dairy and vegetable foods from Morocco including 23 Enterococus faecalis and 15 Enterococcus faecium isolates was studied. All isolates were sensitive to ampicillin, penicillin, and gentamicin. Many E. faecalis isolates were resistant to tetracycline (86.95%), followed by rifampicin (78.26% ciprofloxacin (60.87%), quinupristin/dalfopristin (56.52%), nitrofurantoin (43.47%), levofloxacin (39.13%), erythromycin (21.73%), streptomycin (17.39%), chloramphenicol (8.69%), vancomycin (8.69%), and teicoplanin (4.34%). E. faecium isolates showed a different antibiotic resistance profile: a high percentage were resistant to nitrofurantoin (73.33%), followed by erythromycin (66.60%), ciprofloxacin (66.66%), levofloxacin (60.00%), and rifampicin (26.66%), and only a very low percentage were resistant to tetracycline (6.66%). One isolate was resistant to vancomycin and teicoplanin. The incidence of virulence factors was much higher among E. faecalis isolates, especially for genes encoding for sex pheromones, collagen adhesin, enterococcal endocarditis antigen, and enterococcal surface protein. Isolates with multiple factors (both antibiotic resistance and virulence traits) were also more frequent among E. faecalis isolates, in which one isolate cumulated up to 15 traits. By contrast, several isolates of E. faecium had only very few unwanted traits as compared to only two isolates in E. faecalis. The high abundance of isolates carrying virulence factors and antibiotic resistance traits suggests that the sanitary quality of foods should be improved in order to decrease the incidence of enterococci.     

Antibiotic resistance among enterococcal strains isolated from clinical specimens

The distribution and resistance patterns of clinical isolates of enterococci from hospital patients were compared with those obtained from outpatients. Of 235 enterococcal isolates 212 (90.2%) were identified as Enterococcus faecalis and 23 (9.8%) as E. faecium. E. faecium occurred more frequently in specimens from hospitalized patients than from outpatients (P < 0.001). Over 90% of all E. faecalis isolates were susceptible to ampicillin. Resistance to ampicillin occurred in 66.7% of hospital strains of E. faecium. High-level resistance to gentamicin (MIC > 500 mg/l) was seen in 37.03% of inpatients' and in 11.5% of outpatients' E. faecalis isolates and in 76.2% of hospital isolates of E. faecium. High-level streptomycin resistance (MIC > 2000 mg/l) occurred in 52.8% of E. faecalis and 76.2% of E. faecium hospital isolates. There were no isolates resistant to vancomycin. The community acquired strains isolated from outpatients were more susceptible than isolates from hospitalized patients to all antimicrobial agents tested.     

Antimicrobial resistance of Enterococci in Lebanon

There is little information on the types of Enterococcus spp and their antibiotic resistance patterns in Lebanon. One hundred and fifty-three consecutive clinical enterococcal isolates collected between 1998 and 1999 were tested against 11 antimicrobial agents using disk diffusion and the Etest. The isolates were identified by conventional methods and API-Strep and were found to consist of Enterococcus faecalis (72.5%), Enterococcus faecium (22.9%), Enterococcus avium (3.2%) and Enterococcus gallinarum (1.3%). The percent of resistant strains of E. faecalis and E. faecium respectively were, ampicillin 0.9 and 14%, erythromycin 59% and 40%, tetracycline 72% and 34%, chloramphenicol 32 and 11%, rifampin 36% and 57%, ciprofloxacin, 23% and 34%, norfloxacin 22 and 8%. High level aminoglycoside (HLA) resistance was found in 19% E. faecalis and 9% E. faecium for gentamicin and 36% and 26% for streptomycin. Excellent correlation was observed between the high level disk tests and the Etest in the detection of HLA resistance but not with the regular disks. None of the isolates showed resistance to vancomycin or teicoplanin except for one E. gallinarum isolate which showed intermediate resistance (MIC 16 mg/l) to vancomycin. These variable antimicrobial rates of resistance suggest a surveillance programme for antimicrobial resistance in this country would be helpful to help control infection, guide empirical antibiotic therapy and implement a policy of antibiotic usage.     

High-level gentamicin-resistant Enterococcus faecium strains isolated from bone marrow transplant patients: accumulation of antibiotic resistance genes, large plasmids and clonal strain dissemination

Twenty-six high-level gentamicin-resistant (HLGR) Enterococcus faecium strains colonising neutropenic bone marrow transplant patients were studied. Polymerase chain reaction analysis showed that high-level gentamicin resistance was mediated by the aac(6′)-Ia-aph(2″)-Ie gene; the aph(2″)-Id gene responsible for gentamicin resistance was also detected in 16 strains. Multiple antibiotic resistance was related to the presence of aph(3′)-IIIa, ant(6)-Ia, erm(B), erm (A) and tet(M) genes. Strains clustered into 18 groups according to their plasmid content as well as 16 pulsed-field gel electrophoresis (PFGE) patterns. Although the majority of PFGE patterns were single isolates, three microclones were identified. Hybridisation showed that in the majority of the strains the aac(6′)-aph(2″) gene resided on a large plasmid of ca. 96 kb detected only on PFGE gels. Based on these findings, colonisation by HLGR E. faecium strains was a result of either possibly related plasmid spread or strain dissemination.     

2014-2017年某医院152例尿路感染肠球菌耐药性监测分析

目的:了解2014年1月-2017年1月某医院尿液标本分离肠球菌的临床特点及耐药情况,为肠球菌经验治疗提供参考依据。方法:回顾性分析2014年1月-2017年1月分离自尿液标本肠球菌,VITEK2-compact微生物鉴定系统对细菌进行鉴定,纸片扩散法联合MIC法行抗生素敏感试验,WHONET 5.6和SPSS 20软件进行统计分析。结果:(1)2014年1月-2017年1月尿液标本共检出病原菌908株,主要是大肠埃希菌,其中屎肠球菌84株,粪肠球菌68株,是位于第2位和第3位的病原菌。(2)屎肠球菌对于氨苄西林、高水平庆大霉素、环丙沙星、左氧氟沙星、呋喃妥因的耐药率分别89.6%,63.2%,91.5%,85.7%,69.4%、明显高于粪肠球菌的24.2%(2=65.001,P=0.000)、40.4%(2=8.246,P=0.004)、56.6%(2=26.129,P=0.000)、51.2%(2=21.144,P=0.000)、12.2%(2=50.193,P=0.000);粪肠球菌对于氯霉素的耐药率为33.3%,显著高于屎肠球菌2.6%(2=27.035,P=0.000)。二者对于喹诺酮类抗生素都有较高的耐药率(51.2%)。(3)检出一株对万古霉素耐药的屎肠球菌,耐药率为1.2%(1/84);未检出对万古霉素耐药的粪肠球菌;未发现对利奈唑胺、替加环素耐药的肠球菌。(4)屎肠球菌多重耐药现象严重。结论:尿液标本屎肠球菌与粪肠球菌对抗菌药物耐药性差异大,屎肠球菌多重耐药现象形势严峻,已发现耐万古霉素的屎肠球菌,必须严密监控,尽早诊治,切断传播链。     

肠球菌多重耐药株出现的危险因素和用药探究

目的：了解某院肠球菌感染的临床分布、耐药情况、多重耐药株出现的危险因素及用药情况，为临床肠球菌感染患者抗菌药物的合理用药提供参考依据。方法：对2016年7月-2018年12月检出的肠球菌的标本来源、临床科室分布、药敏结果、患者基础疾病及抗菌药物选择进行回顾性分析。采用χ²检验对肠球菌属粪肠球菌、屎肠球菌、鸟肠球菌的药敏结果进行比较分析；同时采用Logistics回归分析对多重耐药株进行多因素分析。结果：共分离出151株肠球菌属，检出7种肠球菌，其中以粪肠球菌（53.64%）和屎肠球菌（29.13%）为主；屎肠球菌对氨苄西林、环丙沙星、左氧氟沙星、莫西沙星、呋喃妥因、青霉素的耐药率高于粪肠球菌和鸟肠球菌；屎肠球菌对高单位的庆大霉素耐药率为75%（P=0.000），高于粪肠球菌而低于鸟肠球菌的耐药率；粪肠球菌对奎奴普丁-达福普丁的耐药率96.2%（P=0.000）明显高于屎肠球菌（4.54%）和鸟肠球菌（70%）。对粪肠球菌和鸟肠球菌感染，临床上使用甲磺酸左氧氟沙星氯化钠注射液最多，而对屎肠球菌，使用注射用哌拉西林钠他唑巴坦钠最多。2种及2种以上基础疾病、泌尿道感染、既往3个月内使用过抗菌药物和既往3个月内住院是导致肠球菌感染患者发生多重耐药菌感染的危险因素。结论：屎肠球菌感染在该院肠球菌属感染中占主要地位，耐药率方面明显高于粪肠球菌和鸟肠球菌。针对肠球菌感染的患者，临床医师在经验性选择抗菌药物时，需要考虑以上4种多重耐药菌感染的危险因素。     

2020年河南省100所医院神经内科病原菌分布及耐药性分析

目的:探讨2020年河南省100所医院神经内科病原菌的分布及耐药性,为医院感染的防控和临床抗菌药物的合理应用提供依据。方法:收集河南省细菌耐药监测网上有关神经内科病原菌分布及耐药性的相关数据,采用WHONET进行统计分析。结果:共纳入分析的细菌总数为7 507株,其中革兰阴性菌6 094株(81.2%);革兰阳性菌1 413株(18.8%)。结果显示,金黄色葡萄球菌和屎肠球菌对青霉素平均耐药率达89.9%和89.6%,未检测出耐替考拉宁、万古霉素和利奈唑胺的金黄色葡萄球菌。肺炎克雷伯菌、大肠埃希菌、铜绿假单胞菌、鲍曼不动杆菌对亚胺培南和美罗培南平均耐药率分别是23.4%,1.4%,23.1%,69.5%。三级医院纳入分析的细菌总数为6 590株,二级医院为917株;三级医院中肺炎克雷伯菌、鲍曼不动杆菌、铜绿假单胞菌对碳青霉烯类药物耐药率均高于二级医院。结论:该省神经内科患者的病原菌以革兰阴性菌为主,部分病原菌耐药情况严重,尤其是鲍曼不动杆菌,各级医院应该加强防控措施,规范抗菌药物使用,保障医疗安全。     

肠球菌的耐药性分析

目的 研究临床分离的肠球菌对常用抗生素的耐药性及肠球菌与感染性疾病的关系。方法 应用VITEK全自动微生物分析仪对临床标本中分离的88株肠球菌进行鉴定和药物敏感试验。结果 肠球菌对临床常用9种抗生素耐药率以呋喃妥因及万古霉素最低,分别为1．5％、2．3％;其次为氨苄西林和青霉素G,分别为21．3％、34．1％。而对氯霉素、诺氟沙星、四环素及高浓度的庆大霉素、链霉素均呈一定程度耐药,耐药率都在43％以上。结论 肠球菌对临床常用9种抗生素以呋喃妥因及万古霉素最为敏感。本地区所流行菌株对青霉素G仍有较高敏感率。高度耐氨基糖苷类的肠球菌已有相当比例。肠球菌引起的不同部位感染以泌尿系统最为常见。     

血管外科下肢溃疡感染病原学特点及耐药性分析

目的:分析比较血管外科常见下肢静脉性、动脉性溃疡感染的病原学特点及耐药性,为制订合理有效的抗感染方案提供依据.方法:选取2015年7月-2020年7月苏州大学附属第二医院血管外科180例下肢溃疡感染患者(分泌物培养阳性),根据病因分为2组,A组为静脉性溃疡,共114例;B组为动脉性溃疡,共66例,采集创口分泌物相关样本...     

Antimicrobial activity of imipenem against isolates from complicated urinary tract infections

Antimicrobial activity of imipenem was measured using 4725 strains isolated from patients with complicated urinary tract infections (CUTIs) between 1988 and 2000. Imipenem was inactive against methicillin-resistant Staphylococcus aureus and Staphylococcus epidermidis, Enterococcus faecium and some non-fermenting Gram-negative rods. Resistant strains (MIC>16 mg/l) were observed in Staphylococcus haemolyticus (22%), Enterococcus faecalis (4%), Enterococcus avium (8%), Serratia marcescens (5%) and Pseudomonas aeruginosa (7%). Although the prevalence of imipenem-resistant strains of S. aureus, S. epidermidis and P. aeruginosa was sporadically high in some years, no steady increase was seen over the period. Resistant strains were rare in other major uropathogenic species. These results suggest that imipenem is still one of the most reliable antimicrobial drugs.     

Antimicrobial activity and durability of a novel antimicrobial-impregnated bladder catheter

The main objective of this study was to examine the antimicrobial activity and durability of a novel indwelling bladder catheter impregnated with minocycline and rifampin. Thirty antimicrobial-impregnated bladder catheters were inserted transurethrally in spinal cord-injured patients and removed, in six groups of five catheters each, at 3, 7, 10, 14, 17 or 21 days. Removed catheters had detectable zones of inhibition against two different clinical isolates of each of the 10 tested uropathogens (Escherichia coli, Pseudomonas aeruginosa, Proteus mirabilis, Klebsiella pneumoniae, Enterobacter cloacae, Citrobacter diversus, Enterococcus faecalis, Enterococcus faecium, Staphylococcus saprophyticus and Candida albicans) for greater than 14 days after catheter insertion. The residual zones of inhibition and levels of antimicrobial agents in removed catheters were both inversely related to the duration of catheter placement. Minocycline and rifampin were undetectable in serum and urine. These results support the ongoing efforts for examining the clinical efficacy of these experimental bladder catheters.     

7例棉子糖肠球菌临床易感因素分析及抗菌药物治疗策略

目的:了解棉子糖肠球菌的临床易感因素、耐药特点及用药情况,为棉子糖肠球菌感染的防治提供参考。方法:收集2017年1月-2021年12月检出的7例棉子糖肠球菌患者的临床资料,回顾性分析棉子糖肠球菌的临床易感因素,并结合药敏结果及用药选择探讨其抗菌药物治疗策略。结果:7例棉子糖肠球菌中,伤口分泌物为主要标本来源,占42.86%;低蛋白血症、广谱抗菌药物暴露史为棉子糖肠球菌最主要的宿主高风险因素,占比均为85.71%;年龄大于60岁、住院时间大于20 d、使用抗菌药物超过15 d和糖尿病病史也是棉子糖肠球菌的宿主易感因素。药敏结果提示该菌对万古霉素、利奈唑胺、利福平、呋喃妥因和达托霉素敏感率为100%,对左氧氟沙星敏感率为80%,对青霉素类药物、庆大霉素、红霉素及复方磺胺甲唑等敏感性很差。对于棉子糖肠球菌感染,临床根据药敏选择万古霉素或左氧氟沙星治疗有效。结论:棉子糖肠球菌临床易感因素除以往报道的高龄、长时间住院、广谱抗菌药物暴露史以外,还可能存在低蛋白血症和糖尿病病史等因素。其治疗用药可优先选择万古霉素、利奈唑胺和达托霉素,避免选择青霉素、氨苄西林及红霉素等药物。     

Extended antimicrobial resistance screening of the dominant faecal Escherichia coli and of rare resistant clones

Fifty faecal samples from healthy adults were grown on MacConkey agar and three pink colonies were subcultured, identified to species level and their antimicrobial susceptibility determined. Forty-seven samples yielded 141 isolates of Escherichia coli that were susceptible to most antimicrobials. Resistance was noted for ampicillin (30.5%), chloramphenicol (12.1%), tetracycline (23.4%), trimethoprim (24.8%) and co-trimoxazole (22.7%). A direct faecal plating method was used for extended resistance screening with E. coli as the indicator organism. Zone breakpoints were determined using normalised resistance interpretation and gave similar susceptibility results. Eighty-eight isolates of E. coli from within the zones of inhibition revealed four times more antimicrobial resistance. Extended antimicrobial resistance screening both provides the susceptibility profile of the dominant E. coli isolate and detects greater resistance in rare isolates.     

In Vitro Evaluation of High-Level,Gentamicin-Resistant Enterococci Isolated from Bacteremic Patients

We attempted to characterize the susceptibility of high-level, gentamicin-resistant (HLGR, minimum inhibitory concentration [MIC] >2000 μg/ml) enterococcal blood isolates and evaluated a small subset of these isolates for bactericidal synergy. Thirteen Enterococcus faecalis and three Enterococcus faecium isolates that were HLGR were prospectively collected. Standard broth macrodilution techniques were used to determine the MICs and minimum bactericidal concentrations to a variety of antibiotics. Two isolates were evaluated for synergy by time-kill curve methods using combinations of penicillin and streptomycin, teicoplanin and rifampin, and vancomycin and ciprofloxacin. Teicoplanin was the most active antibiotic tested, with all isolates exhibiting susceptibility to this agent. Four E. faecalis isolates and one E. faecium isolate expressed only low-level resistance to streptomycin (LLSR, MlCs 32–64 μg/ml). Penicillin and streptomycin produced bactericidal synergy in the LLSR isolate. The other antibiotic combinations did not result in bactericidal synergy in the two isolates tested. For HLGR enterococci that are only LLSR, the combination of penicillin-streptomycin appears to provide adequate bactericidal activity. Teicoplanin may potentially be useful for streptomycin-resistant HLGR isolates.     

Integron presence in a multiresistant Morganella morganii isolate

A multiresistant strain of Morganella morganii was isolated from a patient affected by several severe pathologies. The isolate was found to be resistant to the following antimicrobials: ampicillin, nalidixic acid, cefalothin, cefoxitin, ceftriaxone, ciprofloxacin, chloramphenicol, streptomycin, erythromycin, gentamicin, novobiocin, penicillin, rifampicin, tetracycline and violet crystal. Mechanisms leading to this multiresistance were studied. Porins of M. morganii multiresistant and wild-type strains were analysed by sodium dodecylsulphate–polyacrylamide gel electrophoresis (SDS–PAGE) and were characterised by their ability to form channels in planar black lipid bilayers. The channels formed by porins from multiresistant and susceptible strains suggested that the porins of the multiresistant strain were not responsible for resistance. A 6.6 kb plasmid (pML2003) was detected, isolated and studied. pML2003 included two integrons. Direct sequencing revealed that one of the integrons contained two cassettes, aminoglycoside adenyltransferase (aadB) and chloramphenicol acetyltransferase (catB3) conferring resistance to aminoglycosides and chloramphenicol, respectively. The second integron contained carbenicillinase (blaP1b) and adenyltransferase (aadA2), which confer resistance to β-lactamases and streptomycin, respectively.