Experimental study of the efficacy of linezolid alone and in combinations against experimental meningitis due to Staphylococcus aureus strains with decreased susceptibility to beta-lactams and glycopeptides.

BACKGROUND: To evaluate in vitro and in vivo efficacies of linezolid, vancomycin, and the combination of linezolid and rifampicin against two Staphylococcus aureus strains with reduced susceptibility to beta-lactams and one of them also to glycopeptides. METHODS: In vitro killing curves and a rabbit model: Meningitis was induced by intracisternal inoculation of 10(8) CFU/ml of each strain. Five hours later (0 h), rabbits were randomly assigned to control or to therapeutic groups. CSF bacterial counts, lactate and protein concentrations, and pharmacokinetic parameters were determined. RESULTS: In vivo: linezolid and its combination with rifampicin reduced bacterial concentrations at 24 h, median cfu/mL 4.85 vs 3.87 (p < 0.05) for linezolid and 5.02 vs 4.21 (p < 0.05) for linezolid + rifampicin, against the glycopeptide intermediate S. aureus (GISA) strain and improved inflammatory parameters. CONCLUSIONS: Despite the need for more experimental data, our results suggest that linezolid and its combinations could be considered as a potential alternative in difficult-to-treat CNS infections and especially in those due to GISA strains and deserve more studies.

Molecular screening of Bartonella species in rodents from south western Spain.

Rodents (87 Mus spretus and 10 Rattus norvegicus) collected in a suburban area of Seville (Andalusia, Spain) between September 2003 and April 2004 were tested by polymerase chain reaction for the presence of Bartonella DNA using primers amplifying a fragment of the 16S/23S rRNA internal transcribed spacer (ITS). Sequence analyses of the ITS of these Bartonella demonstrated that rodents in this region harbored at least three strains: two Bartonella genotypes detected in M. spretus, which clustered separately, and one genotype corresponding with B. tribocorum in R. norvegicus. The finding of Bartonella species in a high proportion of the rodent samples suggests the need to investigate whether these agents might be responsible for cases of febrile illnesses of unknown etiology in Southern Spain.

Neumonía nosocomial por Acinetobacter baumannii / Nosocomial pneumonia due to Acinetobacter baumannii

Acinetobacter baumannii es una importante causa de neumonía nosocomial, especialmente de las neumonías tardías asociadas a ventilación mecánica. En España, ocupa el tercer lugar en frecuencia tras Pseudomonas aeruginosa y Staphylococcus aureus. Los factores de riesgo para el desarrollo de esta neumonía son el traumatismo craneal, la neurocirugía, el síndrome de distrés respiratorio agudo, la aspiración y el tratamiento antimicrobiano previo. El diagnóstico de certeza requiere la toma de muestras respiratorias con técnicas invasivas y de cultivos cuantitativos para diferenciar la infección de la frecuente colonización. La mortalidad cruda de los pacientes con neumonía por A. baumannii asociada a ventilación mecánica es elevada, pero la atribución de ésta a la neumonía es controvertida. El tratamiento antimicrobiano apropiado es un factor pronóstico protector aunque las posibilidades terapéuticas son limitadas. Imipenem es el antimicrobiano de elección y sulbactam el tratamiento alternativo. Colistina es el tratamiento de elección en las neumonías por A. baumannii panresistente. La combinación de rifampicina e imipenem o sulbactam puede ser una alternativa a la colistina en la neumonía por A. baumannii panresistente. Las medidas de control consiguen la erradicación de A. baumannii en los brotes epidémicos, y la reducción del número de casos en las situaciones endémicas. Aunque su aplicación es importante en todo el hospital, las unidades de cuidados intensivos son el lugar clave

Acinetobacter baumannii is a significant cause of nosocomial pneumonia, especially late ventilatorassociated pneumonia. In Spain, A. baumannii is the third leading pathogen after Pseudomonas aeruginosa and Staphylococcus aureus. Risk factors for pneumonia due to A. baumannii are head injury, neurosurgery, acute respiratory distress syndrome, aspiration, and previous antibiotic therapy. Definitive diagnosis requires respiratory samples and invasive techniques with quantitative cultures to differentiate true infections from simple colonizations. The crude mortality of patients with ventilator-associated A. baumannii pneumonia is high, although the attributable mortality is controversial. Adequate empirical antimicrobial therapy of A. baumannii pneumonia is a protective factor, even though the therapeutic options are often limited. The treatment of choice is imipenem and sulbactam may be considered an acceptable alternative. Nowadays, colistin is the treatment of choice in A. baumannii pneumonia caused by panresistant strains. The associations of imipenem and rifampin or imipenem and sulbactam may be acceptable alternatives to colistin in infections caused by these strains. Surveillance measures are essential to eradicate this multidrug-resistant pathogen in outbreaks and reduce the number of episodes in endemic situations. Although these measures are important throughout the hospital, intensive care units are especially high-risk areas

[Nosocomial pneumonia due to Acinetobacter baumannii]. / Neumonía nosocomial por Acinetobacter baumannii.

Acinetobacter baumannii is a significant cause of nosocomial pneumonia, especially late ventilator-associated pneumonia. In Spain, A. baumannii is the third leading pathogen after Pseudomonas aeruginosa and Staphylococcus aureus. Risk factors for pneumonia due to A. baumannii are head injury, neurosurgery, acute respiratory distress syndrome, aspiration, and previous antibiotic therapy. Definitive diagnosis requires respiratory samples and invasive techniques with quantitative cultures to differentiate true infections from simple colonizations. The crude mortality of patients with ventilator-associated A. baumannii pneumonia is high, although the attributable mortality is controversial. Adequate empirical antimicrobial therapy of A. baumannii pneumonia is a protective factor, even though the therapeutic options are often limited. The treatment of choice is imipenem and sulbactam may be considered an acceptable alternative. Nowadays, colistin is the treatment of choice in A. baumannii pneumonia caused by panresistant strains. The associations of imipenem and rifampin or imipenem and sulbactam may be acceptable alternatives to colistin in infections caused by these strains. Surveillance measures are essential to eradicate this multidrug-resistant pathogen in outbreaks and reduce the number of episodes in endemic situations. Although these measures are important throughout the hospital, intensive care units are especially high-risk areas.