Mestrado em Doenças Infecciosas
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Navegando Mestrado em Doenças Infecciosas por Assunto "Agentes antiinfecciosos"
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- ItemAvaliação da eficácia da claritromicina e da amicacina no tratamento da infecção experimental de camundongos BALB/c pelo Mycobacterium massiliense(Universidade Federal do Espírito Santo, 2012-08-21) Colombo, Débora Corona; Palaci, Moisés; Zanini, Marcos Santos; Pereira, Fausto Edmundo LimaNosocomial infections caused by rapidly growing mycobacteria (RGM) have increased significantly in recent years in developed and developing countries. In Brazil, the occurrence of outbreaks due to RGM was reported since last decade. In most cases, a single strain of M. massiliense, named BRA100, was the causative agent. M. massiliense, as well as other species of the group RGM, is resistant to a broad-spectrum of antimicrobial agents, which limits the therapeutic options for the treatment of patients. Due to the lack of clinical trials to establish appropriate therapeutic regimens, the current guidelines for the treatment of infections caused by these microorganisms are based on in vitro antimicrobial activities and clinical case reports. However, there are variations in the correlation between the in vitro susceptibility tests results and the therapeutic response observed, which creates a controversy about their use to support the pharmacotherapy of infections by RGM. In this context, we conducted a study to evaluate the activities of clarithromycin and amikacin against M. massiliense in BALB/c mice. The Minimal Inhibitory Concentration (MICs) of clarithromycin and amikacin for the M. massiliense isolate obtained from a nosocomial outbreak that occurred in 2007, were determined by the broth microdilution assay using cation-adjusted Mueller–Hinton. For in vivo tests, BALB/c mice were infected intravenously with 1 X 107 to 2 x 107 CFU/mL of M. massiliense. Treatments with amikacin or clarithromycin lactobionate were initiated one day post-infection. The mice received daily by subcutaneous injection, 0.1 ml of clarithromycin lactobionate (50mg/kg/12h) or 0.1 ml of amikacin (100mg/kg/day) for 14 days. The mice were sacrificed 24 to 48h after administration of the last dose. Spleen and liver were aseptically removed for determination of weight and number of CFU (log10) per organ. Our results demonstrated in vitro activities of clarithromycin and amikacin against the M. massiliense isolate. Treatment of BALB/c mice with clarithromycin prevented the development of hepatosplenomegaly, as well as the formation of granulomatous lesions for 15 days of infection with M. massiliense. Nevertheless, the clarithromycin and even amikacin were not effective, inducing no reduction of the bacterial population of M. massiliense in the organs. The in vitro susceptibility for bacteria isolated from organs of the mice demonstrated that there was no development of inducible resistance to clarithromycin and amikacin during 12 the treatment. In conclusion, there was no correlation between the activities in vitro and in vivo of clarithromycin and amikacin against M. massiliense.
- ItemCaracterização de cepas hospitalares de enterococcus resistentes à vancomicina (VRE) : resistência aos antimicrobianos e fatores de virulência(Universidade Federal do Espírito Santo, 2013-09-26) Coelho, Marcela Rodrigues; Schuenk, Ricardo Pinto; Nunes, Ana Paula Ferreira; Santos, Kênia Valéria; Spano, Liliana CruzEnterococcus are Gram-positive cocci commonly found in the gastrointestinal tract of humans and animals as well as in soil, water and food. The members of the genus Enterococcus have a remarkable ability to acquire new mechanisms of resistance to antimicrobials, and are considered one of the most versatile bacteria in the current scenario of bacterial resistance and a major cause of hospital acquired infections. Vancomycin-resistant enterococci (VRE) were first identified in the late 1980s in a few European countries. In the present study, hundred VRE isolated from different hospital of Vitória-ES were examined for their resistance genotype and the virulence factors encoded by ace, efaA, gelE, agg and esp genes. The presence of vancomycin resistance genes and species was determined by a polymerase chain reaction using different specific primers (vanA, vanB, ddl E. faecalis and ddl E. faecium). The in vitro susceptibility to ampicillin, penicillin, streptomycin, gentamicin, tetracycline, erythromycin, nitrofurantoin, norfloxacin, ciprofloxacin, teicoplanin, vancomycin and linezolid was evalueted by disk diffusion method. The Minimal Inhibitory Concentration (MIC) to vancomycin was determined by E-test and agar dilution method. All isolates were identified as VRE are the species Enterococcus faecium. All isolates showed MIC to vancomycin >32 µg/ml and proved to harbor the vanA gene in the PCR multiplex. The most in vitro active compound was linezolid. The occurrence of a high frequency of multiple antimicrobial-resistance was detected among these isolates and this phenotype was independent of the origin from they were recovered. Several virulence factors were described for enterococcus, but little is known about the virulence of Enterococcus faecium. The virulence factors were investigated by molecular. The prevalence of the virulence genes was as follows: ace (2%), efaA (5%), gelE (3%), agg (2% and esp (62%). These results showed the low virulence of nosocomial multiple-resistant E. faecium. The knowledge about the role of them on its pathogenesis can contribute to develop new strategies for enterococcus infection combat.
- ItemImpacto do biofilme de Escherichia coli enteroagregativa na susceptibilidade a antimicrobianos(Universidade Federal do Espírito Santo, 2017-09-27) Gonçalves, Mariana Teixeira; Santos, Kênia Valéria dos; Spano, Liliana Cruz; Palaci, Moises; Santos, Andre Luis Souza dosEnteroaggregative Escherichia coli (EAEC) is an emerging pathogen that causes acute and persistent diarrhea worldwide. Biofilm formation, a notable aspect of its pathogenicity, is related to the persistence of infection and requires antimicrobial treatment, and the use of ampicillin, quinolone, sulfamethoxazole/trimethoprim and tetracycline is suggested. As usual techniques of determination of susceptibility do not reflect biofilm activity we aimed to determine the minimum inhibitory concentration of biofilm (MBIC) of nine antimicrobials of eight classes, and to determine the minimum concentration of biofilm eradication (MBEC) by means of (peg-lid), for EAEC clinical samples, for prototype strains EAEC042 and EAEC17-2 and for reference strain ATCC 25922. Minimum inhibitory concentration (MIC) was determined for 35 samples per agar dilution and 20 antimicrobial susceptible samples were selected for ampicillin, cefotaxime, ceftriaxone, chloramphenicol, ciprofloxacin, tetracycline and tobramycin and 19 to sulfamethoxazole/trimethoprim for determination of MBIC. Biofilm was formed in Dulbecco's Modified Eagle Minimum Medium with 0.4% glucose and the biofilm maturation time and formation intensity were determined both in the microplate well and in the peg-lid. The biofilm maturation was achieved with 24 h; eight and 12 samples were classified as strong and weak biofilm forming, respectively. 24 h Biofilm was subjected to folded dilutions of the antimicrobials in Mueller-Hinton broth adjusted with cation and optical density at 650 nm (OD650) was measured after ultrasonic biofilm recovery, before and after incubation at 37 ° C for 6 hours. MBIC revealed that the biofilms were: (i) 100% (20/20) resistant to tetracycline, chloramphenicol and sulfamethoxazole/trimethoprim and 90% (18/20) to ampicillin; (ii) 90% (18/20) with intermediate resistance to ceftriaxone and cefotaxime, (iii) 95% (19/20), ciprofloxacin-sensitive, 80% (16/20) to cefoxitin and 75% (15/20) to tobramycin. Biofilm increased the inhibitory concentration of the antimicrobials by 2 to 4,266.7 times the MIC and the strong forming samples increased the MBIC of ampicillin, ceftriaxone and tobramycin more than the weak formers (p <0.05). The MBEC was always superior to the MBIC and to the last concentration tested, with the exception of cefoxitin and cefotaxime for a sample. Biofilm maturation time of 48h, and 72h did not interfere with MBIC. In conclusion, ciprofloxacin presented excellent activity for EAEC biofilm, followed by cefoxitin and tobramycin, and antimicrobials that were ineffective as ampicillin, sulfamethoxazole/trimethoprim and tetracyclines for the treatment of EAEC infection should not be recommended.