4.1 Principal findings
Our study demonstrated that patients with a higher nursing care level had a higher incidence of blood culture contamination in the ED.
4.2 Strengths and weakness of the study
This study has several limitations. First, the study has a low generalizability because it is a single-center study. Despite this, our hospital accepts a wide range of patients regardless of illness severity or location, and the hospital’s ambulance acceptance is 95% . Additionally, the population pyramid and mean age in Chiba prefecture is similar to Japan’s national population pyramid . Second, people who were not using nursing care services were excluded, such as those living on the street or aged below 65 years. Third, our study did not consider the skin puncture site because of missing data and limitations in our medical chart ordering system. This is relevant because previous studies showed that the skin puncture site, particularly the femoral artery, affected contamination rates . This is pertinent to elderly and critically ill patients who tend to have their specimens collected from the femoral artery because of difficulties in venipuncture. Further research is needed to evaluate the association between procedure factors such as puncture site and patients’ factors including nursing care level to contamination rates.
4.3 Strengths and weaknesses in relation to other studies
Previous studies showed that improvements in blood culture specimen collection and standardized use of sterile gloves and/or chlorhexidine skin disinfectants reduces blood culture contamination [2, 6, 7]. However, few studies have explored the patient factors that may affect blood culture contamination rates. Our study focused on patients’ physical and cognitive function and found that patients with lower ADL or cognitive function tended to have a higher risk for blood culture contamination.
Previous studies have shown that it is more difficult to conduct procedures in the ED compared to the inpatient wards and intensive care unit (ICU) . Multiple studies on the incidence of central line–associated bloodstream infections (CLABSI) showed that CLABSI rates in the ED were similar to those reported in the ICU [19, 20]. These studies involved younger patients (median age = 60 years), whereas our study involved older patients and may be more relevant to the older population.
4.4 Meaning of the study
Our study adopted the Japanese nursing care level classification that uses both ADL and cognitive function to assess a person’s ability to maintain their hygiene. Some previous research showed there are associations between oral hygiene and elderly people’s ADL or cognitive functions . We hypothesized that people with a lower ADL or cognitive function had difficulties maintaining their hygiene, and it may affect blood contamination rate in the ED.
Since most patients at the ED come from their own homes, the patients’ hygiene before their hospital visit may affect the blood culture contamination rate. Several studies on dental health showed that oral hygiene was associated with ADL scores among the homebound older patients. The studies implied that older patients with lower ADL scores needed more support for daily personal care than those with higher ADL scores . Additionally, other studies showed that 10% of the older patients with dementia had resistance-to-care behavior, including physical and/or psychological resistance. People with dementia may show abhorrence and aggressive behavior in response to the invasion of their personal space [22, 23]. This adds to the difficulty of maintaining hygiene.
Guidelines from multiple organizations recommend a systems-based approach comprising education, procedure checklists, hand hygiene, use of sterile gloving, avoidance of femoral catheter insertion, and use of chlorhexidine-alcohol skin disinfectants [2, 6, 7]. Since the older patients need more medical care, they may undergo more frequent medical procedures, such as blood extractions for culture. These patients tend to have difficulties following orders, and more resources like manpower are needed to complete each procedure successfully . Since early administration of appropriate empirical antibiotic therapy decreases mortality from bacteremia , a more careful, appropriate blood culture procedure is required.