RESUMEN
The antimicrobial activity of a new fluoro-quinolone, lomefloxacin (NY-198, SC47111), was evaluated by standardized susceptibility testing methods at ten laboratories in Argentina. Lomefloxacin was found to be the most active drug against 1,316 recent clinical isolates compared directly to norfloxacin, co-trimoxazole, and gentamicin. Only 1.4% of Enterobacteriaceae were lomefloxacin-resistant (MIC greater than 4 micrograms/ml), and the lomefloxacin MIC90 for all staphylococci was 2 micrograms/ml, including methicillin-resistant isolates. Streptococci, enterococci, and some Pseudomonads (9% resistance) were less susceptible to lomefloxacin. Lomefloxacin was the most active against Neisseria gonorrhoeae strains compared to penicillin, cefuroxime, and spectinomycin. Among the tested Mycobacteria, only the nontuberculosis, slow growers had lomefloxacin MICs of greater than 4 micrograms/ml.
Asunto(s)
Antiinfecciosos/farmacología , Bacterias/efectos de los fármacos , Fluoroquinolonas , Quinolonas , 4-Quinolonas , Argentina , Bacterias/aislamiento & purificación , Humanos , Pruebas de Sensibilidad Microbiana , Estudios Multicéntricos como AsuntoRESUMEN
The gas-phase basicity and acidity of tropolone have been determined by Fourier transform ion cyclotron resonance mass spectrometry (FT ICR) techniques. Ab initio calculations at the MP2/-6311+G(d,p) level were carried out to describe the effects that protonation and deprotonation have on the aromaticity and hence on the stability of the system. Experimental and calculated energetics of protonation and deprotonation are in excellent agreement. Our analysis shows that both the protonated and the deprotonated species are stabilized by resonance. As a consequence the acidity of tropolone (341.3 kcal/mol) is enhanced, and this compound is found to be surprisingly as acidic as benzoic acid. This is in good agreement with the results reported in the literature and obtained in DMSO solutions. The intramolecular hydrogen bond becomes significantly weaker upon protonation, and this effect tends to counterbalance the resonance stabilization of the cation. As a consequence, tropolone is found to be slightly less basic than tropone.
RESUMEN
With the purpose of exploring the reliability of the enthalpies of formation calculated using the G3 method, we have examined a series of saturated and unsaturated alicyclic hydrocarbons varying the size and the number of formal double bonds in the molecule. Heats of formation have been calculated at the G3 level through both atomization reactions and bond separation isodesmic reactions, and comparisons with experimental values and with values previously calculated at the G2(MP2) and G2 levels have been made. The quality of the G3-calculated enthalpies of formation using atomization reactions is comparable to that obtained at the G2 level using bond separation reactions, whereas G3 calculations are two to three times faster than G2 calculations.
RESUMEN
Strain effects have been quantitatively evaluated for a set of 22 compounds including ketones (R(2)CO), carboxamides (RCONH(2)), and N,N-dimethylcarboxamides (RCONMe(2)), where R = Me, Et, i-Pr, t-Bu, 1-adamantyl (1-Ad), in their neutral and protonated forms. To this end, use was made of the gas-phase proton affinities and standard enthalpies of formation of these compounds in the gas phase, as determined by Fourier transform ion cyclotron resonance mass spectrometry (FT ICR) and thermochemical techniques, respectively. The structures of 1-AdCOMe and (1-Ad)(2)CO were determined by X-ray crystallography. Quantum-mechanical calculations, at levels ranging from AM1 to MP2/6-311+G(d,p)//6-31G(d), were performed on the various neutral and protonated species. Constrained space orbital variation (CSOV) calculations were carried out on selected protonated species to further assess the contributions of the various stabilizing factors. Taking neutral and protonated methyl ketones as references, we constructed isodesmic reactions that provided, seemingly for the first time, quantitative measures of strain in the protonated species. A combination of these data with the results of theoretical calculations (which also included several "computational experiments") lead to a unified, conceptually satisfactory, quantitative description of these effects and their physical link to structural properties of the neutral and protonated species.
RESUMEN
The importance of hands in the transmission of nosocomial infection has been world wide admitted. However, it is difficult to induce this behavior in health-care workers. The aim of the present work was to point out the importance of hand bacteria colonization, the influence of hand washing and of patient physical examination. One hundred health-care workers were randomly divided in two groups: Group A without hand washing previous to patient physical examination or handling (PPE); group B with hand washing previous to PPE. Direct fingerprint samples in Columbia agar before and after PPE were obtained. The colonies were counted and identified by conventional techniques, and antibiograms according to NCCLS were performed. Before PPE group A participants showed a high number of bacteria regarding group B participants (73.9 Vs 20.7; p < 0.001); 44 out of 50 participants were carriers of potentially pathogen bacteria. No group B participants were carriers of potential pathogen bacteria before PPE. The latter group showed an increase in number of bacteria after PPE (20.7 CFU (before) Vs 115.9 CFU (after); p < 0.001). Sixteen group B participants were contaminated after PPE with potential pathogens such as S. aureus (50% of them methicillin resistant); Escherichia coli, Pseudomonas aeruginosa and Enterococcus faecalis, half of them multiresistant. We can conclude on the importance of these results to implement educational programs and to provide the health-care workers with the proper commodities to fulfill this practice.
Asunto(s)
Infección Hospitalaria/prevención & control , Desinfección de las Manos , Mano/microbiología , Transmisión de Enfermedad Infecciosa de Profesional a Paciente/prevención & control , Recuento de Colonia Microbiana , Humanos , Control de Infecciones/métodosRESUMEN
We report the most frequent species and serovars of enteropathogenic organisms in Rosario from 1985 to 1993. Enteropathogenic Escherichia coli was the most prevalent agent affecting 144/570 (25.2%) children; 0111 represented 41.8%, 055: 13.6%, 0119: 12.7%. Among enterotoxigenic E. coli (ETEC) the most frequent were ETEC-ST 0128:H21 and 0153:H45. Shigella spp were isolated in 8.8%; S. flexneri: 7%, principally type 2 (59.5%); S. sonnei: 1.6%, and S. dysenteriae type 2: 0.2%. Campylobacter spp were found in 6.1% of patients; C. jejuni: 4.6%; C. coli: 1.4% and C. lari: 0.2%; except groups 0 13.50 and 0 4 (2 cases each), no predominant serogroups were found. Salmonella was isolated in 2.8% of cases, being the predominant serovar S. typhimurium until 1986, but a dramatically increase of cases due to S. enteritidis was observed since 1987. There was 1.9% of Aeromonas spp and 2 cases due to Vibrio cholerae non 0-1. No Yersinia was found. In patients with gastroenteritis due to Shigella, Campylobacter, Salmonella, or EPEC as the unique pathogen, leukocytes were observed in the faeces in 70%, 50%, 20%, and 10% of cases respectively.
Asunto(s)
Diarrea/microbiología , Enterobacteriaceae/aislamiento & purificación , Enfermedad Aguda , Aeromonas/aislamiento & purificación , Factores de Edad , Argentina/epidemiología , Campylobacter/aislamiento & purificación , Preescolar , Diarrea/epidemiología , Escherichia coli/aislamiento & purificación , Heces/microbiología , Humanos , Shigella/aislamiento & purificaciónRESUMEN
Corynebacterium urealyticum has been recognised as causing inflammatory cystitis and other human infections. In our knowledge this is the first case of a prosthetic valve endocarditis due to C. urealyticum. It was diagnosed in a 61 year old male patient with a history of rheumatic fever, hypertension and aortic stenosis. He had undergone surgery to replace the aortic valve and to perform triple aortocoronary bypass. The isolate was not multiresistant. Endocarditis due to C. urealyticum is very rare. Corynebacterium species, usually considered as contaminants, frequently colonize surgical cardiovascular areas and must be taken into account as causative agents of severe endocarditis.
Asunto(s)
Infecciones por Corynebacterium , Endocarditis Bacteriana/microbiología , Endocarditis Bacteriana/diagnóstico , Endocarditis Bacteriana/terapia , Resultado Fatal , Humanos , Masculino , Persona de Mediana EdadRESUMEN
We report a case of spinal epidural abscess. In our knowledge this is the first ever reported case due to Fusobacterium nucleatum. An 83 year old female patient with a history of lumbar trauma presented severe lumbalgia. Magnetic resonance showed the unusual anterior location, complicated by psoas abscess. Laminectomy and lumbar drainage were performed. She was treated with ceftriaxone plus metronidazole during 10 days. The evolution was favourable without any residual neurological morbidity.
Asunto(s)
Absceso/microbiología , Espacio Epidural/microbiología , Infecciones por Fusobacterium/complicaciones , Fusobacterium nucleatum , Absceso/diagnóstico , Absceso/cirugía , Anciano , Anciano de 80 o más Años , Espacio Epidural/cirugía , Femenino , HumanosRESUMEN
As part of a multicenter collaborative study the relative frequency of enteropathogenic agents in children less than 5 years of age with acute diarrhea was determined. Rates of isolation were similar as regards sex, age, and season. The frequency of polymorphonuclear cells (PMN) in the stools was significantly higher among patients requiring admission in comparison with ambulatory patients. Enteropathogenic E. coli (EPEC) was isolated more frequently in that group in comparison with outpatients (p < 0.001), mainly among children less than 5 months of age. The most prevalent agents were EPEC (26.1%), enterotoxigenic E. coli (ETEC) (9.7%), Shigella (8.5%), Rotavirus (5.1%), Giardia (3.6%), Campylobacter (3.2%), and Salmonella (2.4%). The EPEC predominant serogroups were 0 111, 0 55, 0 26, and 0 119. ETEC serotypes 0 153:H45 and 0 128:H21 were more often isolated. The predominant species in the genus Shigella were S. flexneri (80.5%), and S. sonnei (9.5%); in the genus Campylobacter, the species were C. jejuni (81.3%), and C. coli (18.7%). Shigella was clearly related to the presence of PMN in the faeces, in children less than 5 months old. Campylobacter was more frequent in ambulatory patients more than one year of age. Rotavirus was found predominantly in autumn and winter. Salmonella and ETEC were more frequent in summer. Giardia was associated with weight loss. In about 10% of the cases there were simultaneous mixed isolations of two or more agents. Salmonella isolates were sensitive to the majority of antimicrobial agents probed. Many Shigella and E. coli were resistant to sulfamethoxazole-trimethoprim and ampicillin (40-80%). Nearly all enterobacteria were sensitive to gentamicin and norfloxacin.
Asunto(s)
Diarrea/microbiología , Enterobacteriaceae/aislamiento & purificación , Enfermedad Aguda , Factores de Edad , Animales , Argentina/epidemiología , Campylobacter/aislamiento & purificación , Preescolar , Diarrea/epidemiología , Diarrea/parasitología , Farmacorresistencia Microbiana , Enterobacteriaceae/efectos de los fármacos , Femenino , Giardia/aislamiento & purificación , Humanos , Lactante , Recién Nacido , Masculino , Rotavirus/aislamiento & purificación , Estaciones del AñoRESUMEN
Bacteremia is associated with high morbidity and mortality. Nosocomial bacteremia is associated with an attributable mortality of 35%. In order to characterize the etiological agent of bacteremia cases during two time periods, 6605 patients were studied as follows: 1) from 1980 to 1982 (n = 2401) and 2) from 1988 to 2000 (n = 4204). A total of 596 cases of bacteremia were detected. The most frequent agents were Staphylococcus aureus, negative coagulase (CNS) Staphylococcus, Klebsiella pneumoniae and Escherichia coli. In the second period, an increase in the frequency of bacteremia caused by gram positive bacteria, particularly gram-positive cocci, was noted. Conversely, gram negative bacteria diminished significantly in the second period, specially enterobacterial species. Methicillin-resistant S. aureus and CNS were significantly more frequently isolated in the second period. Infrequent agents of endocarditis, such as Actinobacillus actinomycetemcomitans, Haemophilus aphrophilus, and Corynebacterium urealyticum, were isolated.
Asunto(s)
Bacteriemia/epidemiología , Infección Hospitalaria/epidemiología , Infecciones por Bacterias Gramnegativas/epidemiología , Infecciones por Bacterias Grampositivas/epidemiología , Argentina/epidemiología , Bacteriemia/microbiología , Infección Hospitalaria/microbiología , Endocarditis Bacteriana/epidemiología , Endocarditis Bacteriana/microbiología , Infecciones por Enterobacteriaceae/epidemiología , Infecciones por Enterobacteriaceae/microbiología , Infecciones por Bacterias Gramnegativas/microbiología , Infecciones por Bacterias Grampositivas/microbiología , Humanos , Estudios Retrospectivos , Infecciones Estafilocócicas/epidemiologíaRESUMEN
A semiprepared medium containing horse globular lysate was evaluated for the isolation of Campylobacter under two incubation atmospheres (5% O2 and candle jar). Studying 19 known strains of C. jejuni, 151 human and 230 animal fecal samples. They were seeded on conventional medium (MC) and on the new medium (MLG) and incubated at 42 degrees C for 24 and 48 h. Campylobacter strains grew better in 5% O2 atmosphere after 48 h of incubation. All the strains that grew or were isolated on MC, could also grow in MLG incubation in candle jar. Campylobacter was isolated from human fecal samples with the same frequency (5.3%) in MC and MLG, independently of the incubation atmosphere employed. These bacteria were isolated in 35.2% and 34.3% of the animal fecal samples seeded on Skirrow modified medium and MLG, respectively. The concordance proportion between both media was 99.13%.
Asunto(s)
Técnicas Bacteriológicas , Campylobacter/aislamiento & purificación , Medios de Cultivo , Eritrocitos , Aerobiosis , Animales , Infecciones por Campylobacter/microbiología , Infecciones por Campylobacter/veterinaria , Campylobacter jejuni/aislamiento & purificación , Diarrea/etiología , Diarrea/microbiología , Enteritis/microbiología , Estudios de Evaluación como Asunto , Heces/microbiología , Caballos/sangre , Humanos , Oxígeno/farmacología , TemperaturaRESUMEN
The incidence of severe infections caused by Lactobacillus spp. is very low. This paper reports a case of a liver abscess and bacteremia due to Lactobacillus rhamnosus. The patient is a 73 year-old woman with antecedent of diabetes mellitus. She has undergone surgery and received antimicrobial therapy (ampicillin plus gentamicin). The clinical outcome was favorable.
Asunto(s)
Bacteriemia/microbiología , Infecciones por Bacterias Grampositivas/microbiología , Lactobacillus/aislamiento & purificación , Absceso Hepático/microbiología , Anciano , Diabetes Mellitus Tipo 2/complicaciones , Susceptibilidad a Enfermedades , Femenino , Humanos , Lactobacillus/patogenicidadRESUMEN
Streptococcus agalactiae is an endogenous bacterium that has emerged in the last 20 years as an etiological agent in both neonatal and perinatal infections, and in immunocompromised patients. The differentiation of the capsular polysaccharide, the presence of surface proteins c, X, R, and molecular methods allow classification in serotypes and genotypes. This identification is a useful tool for epidemiological purposes and virulence studies in this bacterium. The objective of this work was to study the serotypes and the antimicrobial susceptibility of isolates recovered from invasive diseases in different areas of Argentina. In the analyzed sample a fair predominance of Ia and III serotypes was recovered, followed by II and IV serotypes. All the isolates were found to be sensitive to penicillin. A 6% of resistance to erythromycin and a 4.5% to clindamycin were detected. In three of the isolates, constitutive MLS phenotype (resistance to macrolides, lincosamins and streptogramins) was founded, while in the remaining one, inducible MLS phenotype was detected. These results stress the importance of conducting a surveillance of the prevalent serotypes in our country with the goal of future prevention of this disease with an effective vaccine. The knowledge of the antimicrobial susceptibility profile will be also important to obtain therapeutic success in the treatment.
Asunto(s)
Infecciones Estreptocócicas/microbiología , Streptococcus agalactiae/clasificación , Streptococcus agalactiae/efectos de los fármacos , Argentina , Farmacorresistencia Bacteriana , Humanos , Pruebas de Sensibilidad Microbiana , Serotipificación , VirulenciaRESUMEN
Arcanobacterium haemolyticum is a bacterial pharyngeal pathogen that predominantly infects adolescents and young adults. It rarely causes severe infection. A case of sinusitis in an 18-year-old female patient with a skin rash is presented. The strain was susceptible to erythromicin, ampicilin, vancomicin, cephalotin, clindamicin, rifampicin and penicillin. Erythromicin has been proposed as first-line therapy.
Asunto(s)
Actinomycetaceae/aislamiento & purificación , Infecciones por Actinomycetales/microbiología , Rinitis/microbiología , Sinusitis/microbiología , Infecciones por Actinomycetales/tratamiento farmacológico , Adolescente , Femenino , Humanos , Rinitis/tratamiento farmacológico , Sinusitis/tratamiento farmacológicoAsunto(s)
Infecciones por Campylobacter/epidemiología , Enteritis/epidemiología , Adolescente , Adulto , Argentina , Campylobacter fetus/aislamiento & purificación , Niño , Preescolar , Enteritis/microbiología , Heces/microbiología , Femenino , Humanos , Lactante , Masculino , Factores SocioeconómicosAsunto(s)
Flavobacterium , Enfermedades del Recién Nacido/microbiología , Meningitis/microbiología , Sepsis/microbiología , Antibacterianos/farmacología , Líquido Cefalorraquídeo/microbiología , Farmacorresistencia Microbiana , Flavobacterium/efectos de los fármacos , Humanos , Recién Nacido , Enfermedades del Recién Nacido/líquido cefalorraquídeo , MasculinoRESUMEN
The topological analysis of the electron localization function (ELF) has been applied to explore the nature of bonding in thermal cyclizations of (2-ethynylphenyl)triazene and 2-ethynylstyrene. These processes have been proposed to occur through both five- (i.e., coarctate) and six-membered (i.e., pericyclic) transition states. The analysis of electron delocalization, as measured from an irreducible ELF f-localization domain reduction diagram, allows us to characterize these cyclizations of 2-ethynylstyrene in terms of a more pronounced pericyclic or coarctate character than those associated with (2-ethynylphenyl)triazene. The latter evolve through pseudopericyclic and pseudocoarctate pathways. It is found that ELF results are also in good agreement with recent magnetic evidence data obtained from the anisotropy of induced current density (ACID) calculations.