Exposure to extrinsic risk factors in prevalence surveys of hospital-acquired infections: a methodological approach.

The difficulties encountered in studying the presence of extrinsic risk factors in the framework of prevalence surveys of hospital-acquired infections (HAI) have led to the use of a variety of methodological approaches. This study examined the effect of retrospective approaches for obtaining data regarding exposure to extrinsic risk factors. The EPINE database for 1990 was used and a simulation model was created. All the evaluated approaches differed in their impact upon the association between risk factors and infections. Prevalence of exposure on the day of the survey, prevalence of exposure at any time before the survey was conducted, and total prevalence were found to be significantly associated with the probability of exposure and duration of exposure. For exposure periods of less than four days, the prevalence of exposure during the week prior to the survey was higher than that encountered on the day of the survey. In studying exposure to risk factors retrospectively, no evidence-based justification could be found to determine how many days prior to the day of actual exposure should be included in the study. However, the site of infection determined the proportion of devices removed due to HAI, and this proportion was not very high in this study. Limiting data to recording the presence of the risk factor on the day of the survey, without investigating past exposures, can provide an adequate estimate of the burden of extrinsic risk factors in one-day, point-prevalence surveys.

Nosocomial infections in Spain: results of five nationwide serial prevalence surveys (EPINE Project, 1990 to 1994). Nosocomial Infections Prevalence Study in Spain.

OBJECTIVE: To determine trends in rates of nosocomial infections in Spanish hospitals. DESIGN: Prospective prevalence studies, performed yearly from 1990 through 1994. SETTING: A convenience sample of acute-care Spanish hospitals. PARTICIPANTS AND PATIENTS: The number of hospitals and patients included were as follows: 1990, 125 hospitals and 38,489 patients; 1991, 136 and 42,185; 1992, 163 and 44,343; 1993, 171 and 46,983; 1994, 186 and 49,689. A core sample of 74 hospitals, which participated in all five surveys and included a mean of 23,871 patients per year, was analyzed separately. RESULTS: The overall prevalence rate of patients with nosocomial infections in the five studies was as follows: 1990, 8.5%; 1991, 7.8%; 1992, 7.3%; 1993, 7.1%; and 1994, 7.2%. The prevalence rate of patients with nosocomial infection in the core sample of 74 hospitals was 8.9%, 8.0%, 7.4%, 7.6%, and 7.6%, respectively (test for trend, P = .0001). Patients admitted to intensive-care units had a 22.8% prevalence rate of nosocomial infection in 1994. The most common nosocomial infections by primary site were urinary tract infection and surgical site infections, followed by respiratory tract infections and bacteremia. More than 60% of all infections were supported by a microbiological diagnosis. CONCLUSIONS: The EPINE project provides a uniform tool for performing limited surveillance of nosocomial infections in most Spanish acute-care hospitals. Its use helps to spread an accepted set of definitions and methods for nosocomial infection control in the Spanish healthcare system. The surveys indicated that the prevalence of nosocomial infections has been reduced over the last 5 years in a core sample of Spanish hospitals.

[Immunity against tetanus in adults over the age of 49 years]. / Inmunidad frente al tétanos en adultos mayores de 49 años.

BACKGROUND: Despite the existence of an effective, cheap vaccine with few side effects, tetanus remains present in Spain with most of the cases being observed in subjects over the age of 49 years. The present seroepidemiologic study was performed to detect the degree of protection of this population. METHODS: The presence of antitetanic antibodies were determined in 324 subjects over the age of 49 (range: 50-88 years, mean 65.5 +/- 9.8 years) in Guipúzcoa. A passive hemagglutination technique (Tetan test; Istituto Sieroterápico Milanese) was used to detect tetanic antitoxoid antibodies following validation of the technique with a neutralizing test of the toxin in white mouse. RESULTS: Only 12.3% (40/324) of the subjects were considered as immune versus tetanus. The older subjects were the least protected: 7.7% (8/104) of those over 70 years of age versus 17.3% (17/98) of those from 50-59 years of age (chi 2 = 4.34, p = 0.037). The women were globally less protected: 5.4% versus 17% (33/194) males (chi 2 = 9.72; p = 0.002). CONCLUSIONS: Most of the adult population over the age of 49 years in Guipúzcoa is not protected against tetanus. This is in contrast with the situation observed in the infant and adolescent population. Specific preventive measures directed at the adult and elderly population should be undertaken.

[Low risk of acquiring the hepatitis C virus for the health personnel]. / Bajo riesgo de adquisición del virus de la hepatitis C para el personal sanitario.

BACKGROUND: The hepatitis C virus (HCV) is transmitted by the same routes as that of hepatitis B (HBV) and that of the human immunodeficiency virus (HIV). Health care workers have been considered at risk although of different intensity for acquiring the HBV and HIV with the risk of acquiring the HCV being ignored. METHODS: The presence of anti-HCV was investigated in 338 hospital workers, 110 proceeding from risk areas without direct contact with patients (laboratories and cleaning staff), 141 in direct contact and 87 with accidental risk (needle pricks or splashing of blood products) whom, at the time of the accident were anti-HCV negative. In the latter a minimum period of 6 months, which reached one year in 50% of the cases, elapsed to permit seroconversion. Three hundred seventy-seven healthy women were used as controls. The presence of anti-HCV was investigated with a second generation enzymoimmunoanalysis system confirming the results obtained with RIBA. RESULTS: The workers in zones of risk without direct patient contact presented global seroprevalence of anti-HCV of 1.8% with no statistical difference obtained between those who attended patients directly (1.4%) or the control group (2.1%). HCV transmission was not detected in any of the workers who experienced a high risk accident. CONCLUSIONS: The results concerning the study of the risk of health care workers to obtain hepatitis C suggest that the risk of transmission of the hepatitis C virus in these personnel is low.

[Cases of tetanus in Guipuzcoa]. / Casos de tétanos en Guipúzcoa.

In order to evaluate the situation of tetanus in Guipúzcoa and to assess the impact of preventive measures, we studied the incidence, mortality and other aspects of the disease during the past three decades. Ninety eight cases were detected (annual average 3,27 SD 2,6), this figure being reduced over time (7,2 cases per year during the period 1962-1966; 1,8 cases per year between 1987 and 1991). 67,3% were men and 32,7% women. We registered 6 cases of neonatal tetanus, all of them prior to 1976. Since 1969, there has been no cases within the 1-14 age group. Half of the cases detected during the last five years (4/9) were intravenously drug-addicts. Among those living in less populated areas (less than 10.000 population), the risk of developing the disease was four times greater. 33,7% of patients died, being the mortality rate higher among newborns and patients died, and patients over 55. Although the situation was not worse than in other similar environments, the incidence of tetanus should be reduced by reinforcing preventive measures.

Rubella in Guipuzcoa (Basque Country, Spain) a four-year serosurvey.

Since the early 1980s, Spain has practiced mass vaccination of preschool children and selective vaccination of prepubertal girls. Estimated vaccination coverage in the province of Guipúzcoa (Basque Country) in recent years is about 95% (confirmed minimums of 89% for preschool children and 87.5% for 11 to 12 year-old girls). From the seroepidemiological study we could deduce that there was extensive circulation of wild rubella virus until recently (72-75% of unvaccinated girls 10 to 11 years-old had rubella antibody). More than 98% of the population at risk, represented in this study by 13,564 women (67% of all who bore children over a four-year period), possessed rubella antibodies. In the course of the study period the number of subjects (puerperal women and children) susceptible to infection declined. In spite of this favorable situation, the seroepidemiological study disclosed certain gaps that should be corrected to meet the targets for the European Region of the Expanded Programme on Immunization, and to achieve the goal of elimination of wild rubella virus in the area.

Increase of immunity to rubella and interruption of rubella transmission in Gipuzkoa (Basque Country, Spain) after an enhanced vaccination programme.

In Spain, vaccination against rubella was initiated in schoolgirls in the mid-1970s. In Gipuzkoa, subsequent extensions to the vaccination schedule culminated in 1992 with the introduction of the two-dose measles, mumps and rubella vaccine in children and adolescents of both sexes. Moreover, in 1985 a programme for the identification and vaccination of non-immune parturient women was implemented in the region's main hospital. The prevalence of rubella-susceptible parturient women decreased from 3.7 % at the beginning of the study to < 1.5 % by 1992. Despite this overall decrease, 4.8 % of adolescent parturients were susceptible to rubella during 2001--2002. From 1984, the number of reported cases of rubella (children and adults) progressively decreased until 1997, after which there have been no cases of indigenous rubella. There have been no cases of reported congenital rubella since 1984. These results indicate that the vaccine policy carried out in this geographical area has been effective in achieving considerable progress towards rubella elimination.

Neutralizing antibodies in 6-year-old children after five doses of tetanus toxoid.

It has recently been suggested that multiple boosters of tetanus toxoid may enhance serum antitoxin titres but may not necessarily lead to an effective immune response. Tetanus antitoxin titres by haemagglutination inhibition and mouse toxin neutralization tests were determined in sera of 64 children, 5 and 6 years old. Primary vaccination against tetanus was given as four doses of diphtheria-pertussis-tetanus (DPT) vaccine beginning in the second or third month of life, and a booster dose given to schoolchildren at 6 years of age. In our area more than 90% of children receive five doses of tetanus toxoid before their seventh birthday. The children were given 0.5 ml of DPT or DT containing 10 Lf ml-1 tetanus toxoid at each injection. The haemagglutination titres and the toxin neutralization titres were much higher in 6-year-old than in 5-year-old children. We concluded that the fifth dose is an effective booster in 6-year-old children.

Anti-tetanus toxin titers in sera of the women who gave births in 1985 and 1989 in Gipuzkoa (Basque Country, Spain).

14.9% (208/1400) of the women who gave births in 1985 and 1989 in Gipuzkoa (Basque Country, Spain), was considered to have 'protective' levels (> or = 0.01 IU/ml) of tetanus antitoxin as measured by the passive haemagglutination test. Prevalence of protective antibodies was correlated to the years when women were born: 54.7% (64/117) of those born after 1965 were considered to have 'protective' levels (> or = 0.01 IU/ml) of tetanus antitoxin in contrast to those born before 1956 [only 6.2% (21/338)]. This is considered to be due to the infant immunization campaign introduced in 1965 in the Basque Country. Thus, we conclude that the tetanus immunization campaigns in the Basque Country adult population is urgent.

[Immunity against tetanus in childhood]. / Inmunidad frente al tétanos en población infantil.

In order to evaluate the programs of vaccination against tetanus, we have studied the presence of specific antibodies in a sample of children and adolescents from our region. We used a passive hemagglutination test, corroborating the results by a biological assay based on toxin-neutralization. Among the subjects investigated, 93.2% (551/591) had neutralizing toxin-antibodies at a protective level (> or = 0.01 ui/ml). The younger children were more protected (97.5% in children from 1 to 5 years old, and 79.2% in children from 16 to 19 years of age), (X2 = 25.39, p = 0.000-). We did not find any significant differences between the sexes in the degree of protection. Among protected subjects, the higher antibody titers were observed in children from 6 to 10 years old, coinciding with the age of a booster vaccine. The results show an excellent immunization coverage among the childhood population in our region. They also confirm the high effectiveness of this vaccine. However, this high protection was not found among people above the adolescent period.