A Medicolegal Perspective on Hospital Acquired Infections in the Intensive Care Unit
A hospital-acquired infection (HAI) is any infection that originates from a stay in a medical facility. HAIs occur frequently and represent the most common adverse event among hospitalised patients. The highest incidence is seen in the Intensive Care Unit (ICU): nearly 10% of patients who spend two or more days in an ICU will develop at least one infection. HAIs contribute hugely to morbidity and mortality in the patient population and this is also increased in the ICU setting. It has been estimated that HAIs cause around 6% of all deaths annually, thus exceeding the mortality attributed to breast and colon cancer combined. As well as the increased risk of death, hospital stays are considerably lengthened, from an average of 5 days for patients without an infection to around 22 days for those with an HAI. Clearly, HAIs have the potential to confer a significant burden, both clinical and economic.
A recent Europe-wide survey revealed that pneumonia was the most frequently recorded HAI in the ICU setting, with almost all cases being associated with intubation. Ventilator-associated pneumonia (VAP) affects up to a quarter of all patients receiving mechanical ventilation, and the risk of developing it increases with the duration of ventilation and hospital stay. It is also associated with numerous host factors, including age, male gender, severity of illness, and the presence of various medical conditions, including cardiac disease and immune-suppression. VAP has the highest mortality of all HAIs, at up to 75% of patients. Other VAP complications include lung abscesses and the development loculated abscesses in the chest cavity. Rapid diagnosis is vital and physicians must monitor patients undergoing ventilation closely, particularly those with known risk factors. Strategies to reduce the risk of aspiration of secretions with a high bacterial load, as well as the selective use of non-invasive positive pressure ventilation, may help to reduce the incidence of VAP.
The use of urinary catheters is almost universal in the ICU. Not surprisingly, catheter-associated urinary tract infections (CAUTIs) are also very common, and make up around 20% of all HAIs. The risk of bacteria in the urine increases by around 5% for each day that a patient has an indwelling urinary catheter, and, once present, low levels of bacteria or fungi can rapidly multiply, resulting in CAUTIs. However, as the systemic use of antibiotics to prevent CAUTIs has been associated with the development of microbial antibiotic resistance, it should be reserved for high-risk patients only, such as those who are immunosuppressed. A high number of CAUTIs are thought to be preventable, but despite the link with the duration of catheterisation, many hospitals do not have an adequate monitoring system for catheter use and do not use catheter removal reminders or stop-orders. The introduction of guidelines for appropriate catheter usage has seen a reduction in CAUTI incidence rates of up to 45%.
Bloodstream infections (BSIs) are also associated with catheter usage, and complicated infections may require several weeks of antibiotic medication. The incidence appears to be linked to the type of catheter used, as well as the duration of use and placement technique. Therefore, the selection of an appropriate type of catheter and site of insertion, along with meticulous adherence to a sterile insertion technique, should help to reduce the risk of BSI. Strict hygiene measures can also help to prevent surgical site infections (SSIs), which usually occur when microbes invade the wound site at the time of operation. As patients who are carriers of MRSA are at higher risk of SSIs, pre-operative screening should be carried out so that additional preventive measures can be taken.
Sepsis is a significant issue in the ICU, and the condition often develops as a consequence of an HAI. Up to half of all sepsis cases, and around 25% of cases involving organ dysfunction, originate from a hospital stay. Furthermore, mortality in patients with ICU-acquired sepsis is above 40%. This is considerably higher than for the general ICU population, despite their critically ill status. An additional problem often associated with HAIs is the issue of microbial resistance to antibiotic medications. Around 25% of Staphylococcus aureus isolates show resistance to oxacillin, giving rise to MRSA. Resistance to third-generation cephalosporins is also high, at around 17% in E. coliisolates and 44% for both Klebsiella spp. and Enterobacter spp. isolates. Such resistance makes treatment more difficult as it reduces the number of antibiotics available and leads to higher medical costs, longer hospital stays and increased mortality.
HAIs are particularly common in the ICU setting, and many are due to the use of invasive medical devices, such as endotracheal tubes, urinary catheters, and indwelling lines. In addition, the frequency of antimicrobial resistance is very high in the ICU, due to the severity of clinical conditions experienced by patients and the frequent use of antibiotics. However, many HAIs are considered preventable and their incidence could be reduced with better education and strict adherence to infection control measures. It has been estimated that such strategies could reduce the incidence of HAIs by up to 70%.
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