The study of nosocomial infection requires the knowledge of those patient’s characteristics who are at high risk of infection, how often it occurs, the causes of these infections, which allow for more effective prevention and control. It also authorizes the follow of the types of infections that are increasing in incidence, e.g. Bloodstream infections (Banerjee et al. 1991)
According to world health organization (WHO) nosocomial infection can be defined as “An infection occurring in a patient in a hospital or other health care facility in whom the infection was not present or incubating at the time of admission. This includes infections acquired in the hospital, but appearing after discharge, and also occupational infections among staff of the facility “ (Ducel et al. 2002) in other words, they are those infections that acquired in a hospital or a healthcare unit.
Nosocomial infection (NI) also known as Hospital acquired infection (HAI). Is a serious safety issue that affect patients during the hospital visit. It is believed to be a major health problem even in the antibiotic era. studies around the world show that nosocomial infection is the main cause of morbidity and mortality (Mayon-White et al. 1988), In United Sates, almost 90,000 patients die each year due to HAIs, and it is considered the fifth leading cause of death in acute care hospitals.(Klevens et al. 2007; Dancer et al. 2006).
Nosocomial infection is an infection that developed during the patient stay in a hospital and was not present when patient had been admitted, it could be localized or systemic conditions that result from an infectious agents or toxic reaction. (Maazuddin et al. 2014). A nosocomial infection occurs after more than 48 hours of admission (the typical incubation period) (Horan et al. 2008) or within 30 days post discharge where the patient’s hospital stay has been shorter than the incubation period of pathogen. According to many studies almost 50% of surgical site infection (SSI) have appeared after discharge.(Fernandez-Ayala et al. 2006) It could be acquired by the patient’s visitors or health care staff, or the passage through an infected birth canal could be considered as nosocomial infection.
1.2 Types of nosocomial infection:
The Centers for Disease Control and Prevention (CDC), and the National Healthcare Safety Network (NHSN) have classified nosocomial infection sites into 13 main types. This classification is made based on the clinical and biological standard. These types contain almost 50 potentially specific infection sites for surveillance purposes. Surgical wounds and other soft tissue infections, urinary track infection (UTI), respiratory infection, Gastroenteritis, and Meningitis are the most common types of NI (Raka et al. 2006). Increases in the use of chemotherapy, immunotherapy, the advancement in organ transplantation, and the invasive methods for diagnosis and treatment can cause a detectable change in the distribution of the nosocomial site with time. As an example, nosocomial pneumonia has increased within five years, from 17% to 30% (Ferreira et al. 2007).
1.2.2 Urinary tract infections (UTIs):
Urinary tract infections (UTIs) are the most common type of nosocomial infection, which arise in 40% of hospitalized patients (Klevens et al. 2007). It is therefore considered as a critical health issue which associated with the insertion of urinary catheter that had been applied in up to 25% of hospitalized patients (Saint et al. 2000).It is a regularly used medical instrument to collect the urine into a bag through a thin tube for urinary retention and urinary incontinence problems (Nautiyal et al. 2015). This device is considered as the entrance site of opportunistic organisms into the urinary tract, such as: Escherichia coli, the most reported gram-negative, then pseudomonas aeruginosa. All these organisms will increase the chance of a UTI. Others like: klebsiella pneumoniae and Acinetobacter species are also isolated, and it causes less morbidity than other nosocomial infections but it could lead to bacteremia and death in some cases. To prevent the renal damage, blood stream infections and other complications An antifungal or antibiotic must be given.
1.2.1 Surgical site infections (SSIs):
Surgical site infection (SSI) is an infection occurs on surgery wounds after using an invasive procedure. It might involve the skin only, causing a mild infection, or it could be more seriously involve the organ, deep tissues of the wound, or implanted material. Depending on operation type and patient status, the incidence varies from .5 to 15% (Horan et al. 1993). If the patient recovery delayed by one week on average due to the infection further surgical procedures might be required, or it could be controlled by using antibiotic therapy when the results are obtained. Surgical intervention is needed in case of serious infections, such as: Streptococcal gangrene and extensive tissue necrosis since the antibiotic alone is not enough
1.2.3 Nosocomial respiratory tract infection:
Hospital-acquired pneumonia (HAP) is an inflammation in the lung parenchyma caused by a pathogen that develops after 48 hours of hospital admission (American Thoracic Society 2005), while ventilator-associated pneumonia (VAP) is a subset of HAP which occurs after 48 hours of receiving the mechanical ventilation (MV), and within 72 hours of the ventilation. If the infection occurs before 48 hours or after 72 hours, it is assumed to be unrelated to MV. Rates of infection are higher in intensive care unit (ICU), which is believed to be the most common NI among the ICU patients (Craven et al. 1991). Old age, impaired cardiopulmonary function, prolonged intubation, and Immunodeficiency all increased the risk of mortality, which ranges from 33% to 72% in infected patients (Fiel 2001; Lode et al. 2000) VAP could be classified into two categories: Early and late onset. Early-onset, which occurs during the first 4 days after MV it is less sever and is associated with better prognosis than the late-onset, which arises after five days or more of MV, the causative agent will differ in each onset (American Thoracic Society 1995), between 55% to 85% of nosocomial pneumonia is caused by Gram-negative, while gram-positive especially staphylococcus aureus, occurs in about 10-20% of all the cases – so the use of an appropriate antibiotic is required for the treatment (Lynch 2001).
1.2.4 Nosocomial bloodstream infection:
A bloodstream infections (BSIs) are a major cause of morbidity and mortality. In United States, it is the 10th leading cause of death (Freid et al. 2003) with around 250,000 cases occurring annually (Pittet et al. 1997). Types of BDIs could be either a primary/intravascular that arises within the cardiovascular system, while the secondary/extravascular related to theinfections at another sites such as lung, skin and urinary tract. Most of the primary cases are device-related infection associated with central venous catheters (CVCs) (Wisplinghoff et al. 2004), also know as central venous line. BSI could be traced to three sources: skin colonization (exraluminal), hub contamination (intraluminal), and rarely Infusate contamination (figure 1.1) (Crnich & Maki
The most common source of CVCs infection is Skin colonization, where the patient’s skin’s normal flora is the main cause, but it could be transmitted by the health care worker hands (Bjornson et al. 1982). This usually occurs two weeks after an insertion, and skin commensals such as s.aureus and coagulase-negative staphylococci are usually isolated from patient with a primary bloodstream infection. The hub contamination is considered as the main source of BSI in patient with inserted CVC for more than two weeks (Tenney et al. 1986). Contaminated infusate or additives such as contaminated heparin flush, cause the infection by a pathogen introduced into sterile container.
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