Nosocomial infections are infections acquired by patients and staff within a hospital or other health care settings. The World Health Organization (WHO, 2002) defined nosocomial infection as an infection acquired by a patient in a health care facility who was admitted for a different reason than the infection, and which must not be present or incubating at the time of admission. It may be alternately defined as any infection that develops 48 hours after admission or within 48 hours after the patient has been discharged (Shaikh et al., 2008). These infections are also referred to as healthcare-associated infections (HAIs) (Calfee, 2012).
Nosocomial infections occur worldwide, cause significant morbidity and mortality in hospitalized patients, and pose great risk to public health and safety. They occur, on average, in more than 5% of all hospitalized patients and have been cited as one of the top ten causes of death in the United States (WHO, 2002; Calfee, 2012). Many of these infections are avoidable and may be easily prevented through proper preventive measures.
Causative factors of nosocomial infections are microbiological, environmental, and anthropogenic in nature. Patients requiring hospitalization are likely to be immune compromised and already have greater susceptibility towards developing opportunistic infections. This risk is compounded by many treatment-resistant microbiological strains that have developed within healthcare facilities and the leniency of staff towards adequate preventive measures. The setting of a healthcare facility itself is conducive to spreading infections, as infected patients and carriers come in contact with non-infected patients, staff, and visitors (WHO, 2002; Mohammed et al., 2014).
There are several types of nosocomial infections and simplified criteria have been provided to aid proper surveillance in healthcare facilities. The five broad sites of infection are urinary, pulmonary or respiratory, surgical, sepsis, and vascular catheter. Urinary infections are the most common of all nosocomial infections, with 80% associated with the use of indwelling bladder catheter. These cause less morbidity than any other type of nosocomial infection but may progress to bacterial infection in the blood and even death. The infecting microbe may be from the patient's own microbiota (Escherichia coli and others) or acquired from the facility (especially resistant strains of Klebsiella) (WHO, 2002; Calfee, 2012; Mohammed et al., 2014).
Infections of the surgical site are also common and may be affected by patient costs and extent of postoperative care. This type of nosocomial infection is usually acquired during surgery and may be exogenous (from the staff, the air, or the medical equipment) or endogenous (from flora on the patient's skin or surgery site). The greatest risk factor of infection is the extent of exposure of the patient to infectious agents, largely dependent on the length of the operation and the patient's condition. Since most surgical operations are often complex and invasive (even if regarded as routine), other risk factors are at play such as the surgeon's technique, infection at other sites, preoperative shaving, and the general experience of the team (WHO, 2002; Calfee, 2012; Mohammed et al., 2014).
Nosocomial pneumonia has great risk of occurring in patients who are in intensive care units (ICUs) and are hooked up to ventilator machines. This is often caused by microbes that colonize the stomach, upper airway and bronchi, and the lungs. Bacteria may come from the patient's digestive system, nose, and throat, or from contaminated equipment. Other respiratory nosocomial infections may also occur in patients who are not intubated. Viral bronchiolitis, tuberculosis, influenza, and secondary bacterial pneumonia may occur especially in pediatric and geriatric units, whose patients even when healthy already have considerably weaker immune systems than healthy adults (WHO, 2002; Shaikh et al., 2008; Calfee, 2012).
Sepsis or infection of the blood especially by bacteria (bacteremia) occurs less frequently than other nosocomial infections but has high rates of fatality, especially with particularly virulent strains of microorganisms such as multidrug-resistant Staphylococcus and Candida spp. Infection may occur through the central line (central venous catheter) at the entry site on the skin or in the subcutaneous path ("tunnel") of the device (WHO, 2002; Calfee, 2012; Mohammed et al., 2014). Other nosocomial infections that occur frequently in patients include the skin and soft tissues, often leading to open sores that may progress to systemic infection. Gastroenteritis is the most common nosocomial infection in children but may also occur in adults. Finally, infections of the eyes, nose, and throat such as sinusitis, conjunctivitis, strep throat, etc. may also occur (WHO, 2002).
Prevention of outbreaks of nosocomial infections is essential in keeping all members of the population safe. Since a great number of these infections are easily preventable, healthcare providers must adhere to proper guidelines to reduce their occurrence. As such, personnel each have roles to play and everyone must cooperate in order to maximize the efficiency of the preventive effort. WHO (2002) guidelines propose the establishment of an Infection Control Committee, which proactively encourages information sharing and cooperation among a multidisciplinary group of hospital staff members. The Committee must be responsible for assessing and reviewing surveillance & prevention activities, epidemiological & epidemics data, and potential risks with new technologies. It must also actively try to improve healthcare practice and to ensure proper staff training and adequate adherence to the set guidelines (WHO, 2002).
Nosocomial infections pose a great burden to the human population in general and must be dealt with carefully and consistently. Preventive effort must be focused on healthcare facilities to reduce the rates of these infections. Overcoming the sheer amount of effort, coordination, communication, and commitment would pave the path to potentially eliminating preventable nosocomial infections altogether.
Calfee, D. P. (2012). Crisis in hospital-acquired, healthcare-associated infections. Annual Review of Medicine 63: 359-371.
Mohammed, M., Mohammed, A. H., Mirza, M. A., and Ghori, A. (2014). Nosocomial Infections: An Overview. International Research Journal of Pharmacy 5(1): 7-12.
Shaikh, J. H., Devrajani, B. R., Shah, S. Z., Akhund, T., and Bibi, I. (2008). Frequency, pattern and etiology of nosocomial infection in intensive care unit: an experience at a tertiary care hospital. Journal of Ayub Medical College Abottabad 20(4): 37-40.
World Health Organization (2002). Prevention of hospital-acquired infections: A practical guide (2nd Ed.). Malta: WHO.