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Nosocomial infections (NIs) increase patient morbidity and mortality, hospital stay and economic cost, and are correlated with antibiotic resistance. According to a prevalence study carried out by the WHO in 55 hospitals of 14 countries, 8.7% of patients admitted to a hospital suffered an NI; this means that approximately 1.4 million people will develop a health-related infection ; for these patients, the mean hospital stay will be 14 days longer [2,3]. NIs are especially relevant in certain hospital areas (intensive-care units (ICUs)), where their incidence is two-fold to five-fold higher [4,5]. Identification of the factors related to NI is crucial for the development of preventive strategies [1,2,6], which require an integrated and continuous education programme to improve the care provided to patients by healthcare workers ; adequate hand hygiene is probably the most cost-effective measure [1,7–11].
Although there is enough evidence to show a relationship between improvements in hand hygiene practices and a decrease in NI incidence [6–13], there is a low level of adequate compliance with these recommendations in the routine of daily practice, rarely exceeding 40–50% [10,14–18].
Given the relevance of NI control in the ICU and the benefit attributed to the use of barrier measures (especially hand hygiene of healthcare staff) in the prevention of such infections, we performed this study with the following aims: (i) to determine the frequency and epidemiology of NIs in the ICU at a second-level hospital; (ii) to determine the main risk factors associated with them; (iii) to analyse the prognostic factors associated with mortality in patients admitted to this ICU; and (iv) to evaluate the influence of a hand-washing programme on compliance with hand-hygiene practices and on the development of NI.
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The main aims of our study were to analyse risk factors for NI in an ICU and the influence of a hygiene promotion programme on infection control. The data concerning the development of NI in our cohort were obtained from the patients admitted to the ICU during the two observation periods; despite the fact that P1 was distributed in different months from those of P2, the analysis of the population characteristics in both periods showed that they were clinically comparable. The statistically significant difference between the average ages of the populations, which was probably of little relevance from the clinical point of view, was not translated into a clinical difference in past or present pathology between the two groups, and only chronic liver dysfunction was more frequent in group B than in group A. Although patient severity of disease as estimated by the APACHE II index was similar, the classification according to the CDC score showed inequalities. Nevertheless, on grouping of patients into two categories including, on the one hand, CDC codes 1–3 (corresponding to clinically stable situations), and, on the other, CDC codes 4 and 5 (unstable clinical situations), significant differences were not found between the groups. With regard to patient exposure to most of the invasive procedures considered to be risk factors for the development of NI, the results were also similar, with the exceptions of arterial catheterization (less frequent in group A) and the administration of antibiotics before ICU admission (more frequent in group A). The fact that exposure to antibiotic treatment before ICU admission was more frequent in group A could be explained by the higher frequency of community infections in this group of patients (23.29% vs. 17.52%; p <0.05).
Among the NIs diagnosed in our ICU, ventilator-associated pneumonia (VAP) was the most frequent (21.1% of all episodes of NI), as reported by previous studies , but it was closely followed by urinary infection associated with urinary catheter use (19.9%). The rate of infections related to central catheter use (without bacteraemia) (21.1%) was equal to that of VAP, but most of the publications do not refer to this type of infection, and they only assess bacteraemia associated with venous catheter use.
Identification of the factors that increase the risk of developing NI is paramount, in order to enable the elaboration of strategies for the prevention of such complications. In our cohort, in the multivariate analysis, we mainly found extrinsic risk factors, in agreement with previously published data [5,14,20–22]. These extrinsic variables were central venous catheter inserted for more than 5 days (OR 18.8) and the presence of tracheostomy (OR 25.3). Both are directly related to the types of NI most frequently diagnosed in our ICU: VAP and central venous catheter infection (CVC). However, urinary catheter use was not an independent risk factor for the development of NI, which is somewhat striking; perhaps the higher incidence of the other two types of NI is the cause of this result.
Fifteen per cent of the patients in our cohort died; the factors that were statistically associated with a fatal outcome were older age (>65 years) (OR 2.9), diabetes mellitus (OR 1.3), administration of antibiotic treatment during hospital stay before ICU admission (OR 3.3), level 3 according to the CDC severity score (OR 4.3), APACHE II score >15 (OR 4), pulmonary artery catheterization (OR 23.5), invasive mechanical ventilation for more than 5 days (OR 7.3), and presence of a urinary catheter for more than 3 days (OR 2.1). However, having undergone non-urgent surgery was a protective factor, probably because these patients developed fewer complications than the patients who were admitted for ‘urgent’ reasons. The identification of prolonged mechanical ventilation and central venous catheterization as risk factors associated with mortality coincides with the findings of previous studies . Other risk factors mentioned in the literature were included in our analyses, such as renal failure, parenteral nutrition, and the presence of tracheostomy, but statistical significance was not detected. Unlike in other studies, in our cohort the development of NI was not a risk factor for death [23,24].
One of the goals of this work was the implementation of an educational programme to improve hand-washing practices and the placement of alcohol gel at the patients’ headboards [11–13,25]. As previously mentioned [1,10–18], hand-washing is usually considered to be the most important measure for the prevention of NI and dissemination of microorganisms. Even so, compliance with this measure does not exceed 50% at most, and although the relevance of hand-washing is generally admitted, some authors find that, under ideal circumstances, hand hygiene may influence only 40% of all NIs in an ICU . Nevertheless, the impact of hand-washing on NI prevalence seems to have been clearly proved [7,12,13], and, even taking into account what has previously been stated, and the fact that, at worst, there is a beneficial effect on 40% of the NIs in the ICU, where the incidence is usually higher than in the rest of the hospital, hand-washing has already been shown to be important.
The compliance with hand-washing (considering both hygienic washing with water and soap, and disinfection with iodine or alcohol gel) obtained in the first observation period of healthcare activities was similar to that reported by other authors [18,26,27], usually under 50%. The prevalence of compliance before patient care was lower than that obtained after care [18,27], which can be explained by workers’ perception of their own health risk. In P2, the frequency of hand-washing, both before and after healthcare, increased significantly, as has been found in previous studies [17,18,27]. However, it should be pointed out that, even though the frequency of hand-washing increased, it continued to be performed mainly with water and soap (hygienic washing), although hand disinfection with hydroalcoholic antiseptics is more advisable [7,10,25]. Considering all the products for hand hygiene available in the second observation period, disinfection with alcohol gel was performed in only 24.8% of hand-washing episodes before patient care and in 7.6% after care. Therefore, it is obvious that, with the implementation of the programme, we did not succeed in raising enough awareness of the importance of this recommendation, which is currently considered to be the reference standard for hand hygiene . Perhaps this explains why, despite the fact that the number of patients who developed NIs in the ICU showed a significant decrease in the second period of study (13.7% in P1 vs. 8.3% in P2; p <0.05), having been admitted during P1 was not a statistically significant risk factor for the development of NI. Multiple factors are involved in the development of NI, and establishing the association between improvement in hand hygiene and the reduction in NIs is difficult. In a meta-analysis of clinical studies , only nine publications registered a positive impact of compliance with hand hygiene measures on the prevention of NI, and only four reported important reductions in NIs.