M. Delgado Rodríguez

Preoperative stay as a risk factor for nosocomial infection

To evaluate the relationship between duration of preoperative stay and the risk of nosocomial infection, we studied 449 patients who underwent surgery at the University Hospital of Granada during the first six months of 1986. Patients were chosen from two cross-sectional surveys. Nosocomial infection was studied throughout each patients hospital stay. Other variables included preoperative stay, age, severity and total length of stay. The data were analyzed by comparing nosocomial infection for different lengths of preoperative hospitalization, age and severity by calculating the Odds Ratio. The effects of age and severity were studied by stratifying patients by duration of preoperative stay. Two multivariate regression models were used to confirm the results of the stratified analysis. The results suggest that lengthening the preoperative stay may increase the risk of nosocomial infection in surgical wounds and in other sites, and may simultaneously potentiate the effects of other risk factors such as age and severity of the patients condition, whose influence on susceptibility to infection increases with the duration of preoperative stay.

EFFECT OF PENICILLIN AND CHLORAMPHENICOL ON THE GROWTH AND ENDOTOXIN RELEASE BY N. MENINGITIDIS

The action of two antibiotics, penicillin and chloramphenicol, on bacterial growth and endotoxin liberation was studied in 18 strains of Neissevia meningitidis isolated from blood and CSF of patients with meningococcal infections. The antibiotics were administered both separately and in combined form in doses equivalent to 1 MIC and 100 MIC. Penicillin was found to produce a faster and more intense bactericidal effect than chloramphenicol during the first hour, whereas at 12 h these differences were not significant. This could explain the initial worsening observed in some infected patients when large doses of penicillin are administered. An increased liberation of endotoxin after adding penicillin was observed in six of the strains studied, whereas the remaining 12 did not show significant increases. The six strains (belonging to serogroup B) were known to have an enhanced capacity for spontaneous endotoxin liberation.

Endotoxin liberation by strains of N. meningitidis isolated from patients and healthy carriers.

The main objective of this study was to assess whether the capacity of Neisseria meningitidis to release endotoxin depends upon the type of strain or upon bacterial mass. Endotoxin release was studied in 32 strains isolated from patients with meningococcal infections and in 49 from asymptomatic carriers, using a quantitative test (limulus test with a chromogenic substrate). The results show that the strains from patients release significantly higher amounts of endotoxin than strains from carriers regardless of serogroup and isolation site. No correlation was found between stage of bacterial growth and the amount of endotoxin liberated. These findings suggest that endotoxin liberation is a characteristic of certain strains of N. meningitidis and is not determined simply by bacterial mass.

Prevalence of dental caries in schoolchildren of the province of Granada (Spain)

A sample of 3,347 students between 5 and 14 years of age was selected from the entire student population in the province of Granada (Spain) to study the prevalence of dental caries and several risk factors for the disease. Decay was ascertained in the study population by mean of the following indices: df, DMF, and DMFS. Risk factors considered were the level of oral hygiene, number of between-meal sugar-containing food, and flouride concentration in drinking water. The indices mentioned showed a clear relationship to the age of the participants in the study. The level of oral hygiene did not show a clear association with dental caries measured through the df and DMF indices. Curiously, a higher correlation was noted between the disease in deciduous teeth and fluoride concentration than between the disease in permanent teeth and the latter factor.A sample of 3,347 students between 5 and 14 years of age was selected from the entire student population in the province of Granada (Spain) to study the prevalence of dental caries and several risk factors for the disease. Decay was ascertained in the study population by mean of the following indices: df, DMF, and DMFS. Risk factors considered were the level of oral hygiene, number of between-meal sugar-containing food, and flouride concentration in drinking water. The indices mentioned showed a clear relationship to the age of the participants in the study. The level of oral hygiene did not show a clear association with dental caries measured through the df and DMF indices. Curiously, a higher correlation was noted between the disease in deciduous teeth and fluoride concentration than between the disease in permanent teeth and the latter factor.

Utilización de la densidad de incidencia, en la valoración de faciores de riesgo de la infección nosocomial

Resumen En la literatura se han propuesto las medidas de densidad de incidencia para la valoracion de la infeccion nosocomial. A traves de una cohorte retrospectiva de 843 pacientes se realiza una comparacion entre la razon de densidades de incidencia (RDI) y el cociente de incidencias acumuladas o riesgo relativo (RR) en la cuantificacion de factores de riesgo de la infeccion hospitalaria. Las variables que se analizaron fueron la intervencion quirurgica, su duracion, el tipo de cirugia, la gravedad de la enfermedad subyacente y la edad. En todas las situaciones la RDI fue inferior al RR, al eliminar la prolongacion de estancia producida por los distintos factores de riesgo. Ejemplos de ello fueron el que la RDI para la operacion fue de 2,78, mientras que el RR ofrecio valores de 6,46, o en la edad, donde los mayores de 60 anos presentaron un RR significativo de 1,67, mientras que la RDI fue de 0,96. Esto sugiere que el empleo de la RDI facilitaria la comparabilidad de los resultados entre diferentes centros en la cuantificacion de factores de riesgo para la infeccion nosocomial, aparte de cuantificar con mas exactitud los distintos factores de riesgo, lo que tiene importancia a la hora de establecer las medidas de control.