| Nosocomial infection | |
|---|---|
| Other names | HAI (Healthcare-Associated Infections) |
 | |
| Contaminated surfaces increase cross-transmission | |
| Specialty | Infectious disease |
Ahospital-acquired infection, also known as anosocomial infection (from the Greeknosokomeion, meaning "hospital"), is aninfection that is acquired in ahospital or otherhealthcare facility.[1] To emphasize both hospital and nonhospital settings, it is sometimes instead called ahealthcare-associated infection.[2] Such an infection can be acquired in a hospital,nursing home,rehabilitation facility, outpatient clinic, diagnostic laboratory or other clinical settings. A number of dynamic processes can bring contamination into operating rooms and other areas within nosocomial settings.[3][4] Infection is spread to the susceptible patient in the clinical setting by various means. Healthcare staff also spread infection, in addition to contaminated equipment, bed linens, or air droplets. The infection can originate from the outside environment, another infected patient, staff that may be infected, or in some cases, the source of the infection cannot be determined. In some cases the microorganism originates from the patient's ownskin microbiota, becomingopportunistic after surgery or other procedures that compromise the protective skin barrier. Though the patient may have contracted the infection from their own skin, the infection is still considered nosocomial since it develops in the health care setting.[5] The termnosocomial infection is used when there is a lack of evidence that the infection was present when the patient entered the healthcare setting, thus meaning it was acquired or became problematic post-admission.[5][6]
During 2002 in the United States, theCenters for Disease Control and Prevention estimated that roughly 1.7 million healthcare-associated infections, from all types ofmicroorganisms, includingbacteria andfungi combined, caused or contributed to 99,000 deaths.[7] InEurope, where hospitalsurveys have been conducted, the category ofgram-negative infections are estimated to account for two-thirds of the 25,000 deaths each year.[8] Nosocomial infections can cause severepneumonia and infections of theurinary tract,bloodstream and other parts of the body.[9][10] Many types displayantimicrobial resistance, which can complicatetreatment.[11]
In the UK about 300,000 patients were affected in 2017, and this was estimated to cost theNHS about £1 billion a year.[12]
In-dwelling catheters have recently been identified with hospital-acquired infections.[14] To deal with this complication, procedures are used, calledintravascular antimicrobial lock therapy, that can reduce infections that are unexposed to blood-borne antibiotics.[15] Introducing antibiotics, including ethanol, into the catheter (without flushing it into the bloodstream) reduces the formation ofbiofilms.[13]
| Route | Description |
|---|---|
| Contact transmission | The most important and frequent mode of transmission of nosocomial infections is by direct contact. |
| Droplet transmission | Transmission occurs when droplets containing microbes from the infected person are propelled a short distance through the air and deposited on the patient's body; droplets are generated from the source person mainly by coughing, sneezing, and talking, and during the performance of certain procedures, such as bronchoscopy. |
| Airborne transmission | Dissemination can be either airborne droplet nuclei (small-particle residue {5μm or smaller in size} of evaporated droplets containing microorganisms that remain suspended in the air for long periods of time) or dust particles containing the infectious agent. Microorganisms carried in this manner can be dispersed widely by air currents and may become inhaled by a susceptible host within the same room or over a longer distance from the source patient, depending on environmental factors; therefore, special air-handling and ventilation are required to prevent airborne transmission. Microorganisms transmitted by airborne transmission includeLegionella,Mycobacterium tuberculosis and therubeola andvaricella viruses. |
| Common vehicle transmission | This applies to microorganisms transmitted to the host by contaminatedfomite items, such as food, water, medications, devices, and equipment. |
| Vector borne transmission | This occurs when vectors such as mosquitoes, flies, rats, and other vermin transmit microorganisms. |
Contact transmission is divided into two subgroups: direct-contact transmission and indirect-contact transmission.
| Route | Description |
|---|---|
| Direct-contact transmission | This involves a direct body surface-to-body surface contact and physical transfer of microorganisms between a susceptible host and an infected or colonized person, such as when a person turns a patient, gives a patient a bath, or performs otherpatient-care activities that require direct personal contact. Direct-contact transmission also can occur between two patients, with one serving as the source of the infectious microorganisms and the other as a susceptible host. |
| Indirect-contact transmission | This involves contact of a susceptible host with a contaminated intermediate object, usually inanimate, such as contaminated instruments,needles, or dressings, or contaminated gloves that are not changed between patients. In addition, the improper use of saline flush syringes, vials, and bags has been implicated in disease transmission in the US, even when healthcare workers had access to gloves, disposable needles, intravenous devices, and flushes.[16] |
Alongside reducing vectors for transmission, patient susceptibility to hospital-acquired infections needs to be considered. Factors which render patients at greater risk of infections include:
Given the association between invasive devices and hospital-acquired infections, specific terms are used to delineate such infections to allow for monitoring and prevention. Noted device-associated infections includeventilator-associated pneumonia, catheter-associated blood stream infections,catheter-associated urinary tract infections anddevice-associated ventriculitis. Surveillance for these infections is commonly undertaken and reported by bodies such as theEuropean Centre for Disease Prevention and Control andCenters for Disease Control and Prevention.[citation needed]
Controlling nosocomial infection is to implementQA/QC measures to thehealth care sectors, and evidence-based management can be a feasible approach. For those with ventilator-associated or hospital-acquired pneumonia, controlling and monitoring hospitalindoor air quality needs to be on agenda in management,[21] whereas for nosocomialrotavirus infection, ahand hygiene protocol has to be enforced.[22][23][24]
To reduce the number of hospital-acquired infections, the state of Maryland implemented the Maryland Hospital-Acquired Conditions Program that provides financial rewards and penalties for individual hospitals. An adaptation of the Centers for Medicare & Medicaid Services payment policy causes poor-performing hospitals to lose up to 3% of their inpatient revenues, whereas hospitals that are able to decrease hospital-acquired infections can earn up to 3% in rewards. During the program's first two years, complication rates fell by 15.26% across all hospital-acquired conditions tracked by the state (including those not covered by the program), from a risk-adjusted complication rate of 2.38 per 1,000 people in 2009 to a rate of 2.02 in 2011. The 15.26% decline translates into more than $100 million in cost savings for the health care system in Maryland, with the largest savings coming from avoidance of urinary tract infections,sepsis and other severe infections, andpneumonia and other lung infections. If similar results could be achieved nationwide, the Medicare program would save an estimated $1.3 billion over two years, while the US healthcare system as a whole would save $5.3 billion.[25]
Hospitals have sanitation protocols regardinguniforms, equipmentsterilization, washing, and other preventive measures. Thoroughhand washing and/or use ofalcohol rubs by all medical personnel before and after each patient contact is one of the most effective ways to combat nosocomial infections.[26] More careful use ofantimicrobial agents, such asantibiotics, is also considered vital.[27] As many hospital-acquired infections caused by bacteria such as methicillin-resistantStaphylococcus aureus, methicillin-susceptibleStaphylococcus aureus, andClostridioides difficile are caused by a breach of these protocols, it is common that affected patients make medical negligence claims against the hospital in question.[28]
Sanitizing surfaces is part of control measures to reduce nosocomial infections in healthcare environments. Modern sanitizing methods such asNon-flammable Alcohol Vapor in Carbon Dioxide systems have been effective against gastroenteritis, methicillin-resistantStaphylococcus aureus, and influenza agents. The use ofhydrogen peroxide vapor has been clinically proven to reduce infection rates and risk of acquisition. Hydrogen peroxide is effective against endospore-forming bacteria, such asClostridioides difficile, whereas alcohol is ineffective.[29][non-primary source needed] Ultraviolet cleaning devices may also be used to disinfect the rooms of patients infected withClostridioides difficile or methicillin-resistantStaphylococcus aureus after discharge.[30][non-primary source needed]
Despite sanitation protocol, patients cannot be entirely isolated from infectious agents. Furthermore, patients are often prescribed antibiotics and other antimicrobial drugs to help treat illness; this may increase theselection pressure for the emergence of resistant strains.[31]
Sterilization goes further than just sanitizing. It kills all microorganisms on equipment and surfaces through exposure to chemicals, ionizing radiation, dry heat, or steam under pressure.[32]
Isolation is the implementation of isolating precautions designed to prevent transmission of microorganisms by common routes in hospitals. (SeeUniversal precautions andTransmission-based precautions.) Because agent and host factors are more difficult to control, interruption of transfer of microorganisms is directed primarily at transmission for example isolation of infectious cases in special hospitals and isolation of patient with infected wounds in special rooms also isolation of joint transplantation patients on specific rooms.[citation needed]
Handwashing frequently is called the single most important measure to reduce the risks of transmittingskin microorganisms from one person to another or from one site to another on the same patient. Washing hands as promptly and thoroughly as possible between patient contacts and after contact withblood,body fluids,secretions,excretions, and equipment or articles contaminated by them is an important component of infection control and isolation precautions.The spread of nosocomial infections, among immunocompromised patients is connected with health care workers' hand contamination in almost 40% of cases, and is a challenging problem in the modern hospitals. The best way for workers to overcome this problem is conducting correct hand-hygiene procedures; this is why the WHO launched in 2005 the GLOBAL Patient Safety Challenge.[33]
Two categories of micro-organisms can be present on health care workers' hands: transient flora and resident flora. The first is represented by the micro-organisms taken by workers from the environment, and the bacteria in it are capable of surviving on the human skin and sometimes to grow. The second group is represented by the permanent micro-organisms living on the skin surface (on the stratum corneum or immediately under it). They are capable of surviving on the human skin and to grow freely on it. They have low pathogenicity and infection rate, and they create a kind of protection from the colonization from other more pathogenic bacteria. The skin of workers is colonized by 3.9 × 104 – 4.6 × 106cfu/cm2. The microbes comprising the resident flora are:Staphylococcus epidermidis,Staphylococcus hominis, andMicrococcus,Propionibacterium,Corynebacterium,Dermabacter, andPittosporum spp., while transient organisms areStaphylococcus aureus, andKlebsiella pneumoniae, andAcinetobacter, Enterobacter andCandida spp. The goal of hand hygiene is to eliminate the transient flora with a careful and proper performance of hand washing, using different kinds of soap, (normal and antiseptic), and alcohol-based gels. The main problems found in the practice of hand hygiene is connected with the lack of available sinks and time-consuming performance of hand washing. An easy way to resolve this problem could be the use of alcohol-based hand rubs, because of faster application compared to correct hand-washing.[34]
Improving patient hand washing has also been shown to reduce the rate of nosocomial infection. Patients who are bed-bound often do not have as much access to clean their hands at mealtimes or after touching surfaces or handling waste such as tissues. By reinforcing the importance of handwashing and providing sanitizing gel or wipes within reach of the bed, nurses were directly able to reduce infection rates. A study published in 2017 demonstrated this by improving patient education on both proper hand-washing procedure and important times to use sanitizer and successfully reduced the rate of enterococci andStaphylococcus aureus.[35]
All visitors must follow the same procedures as hospital staff to adequately control the spread of infections. Moreover, multidrug-resistant infections can leave the hospital and become part of the communityflora if steps are not taken to stop this transmission.[citation needed]
It is unclear whether or not nail polish or rings affected surgical wound infection rates.[36]
In addition to hand washing,gloves play an important role in reducing the risks of transmission of microorganisms. Gloves are worn for three important reasons in hospitals. First, they are worn to provide a protective barrier for personnel, preventing large scale contamination of the hands when touching blood, body fluids, secretions, excretions, mucous membranes, and non-intact skin. In the United States, theOccupational Safety and Health Administration has mandated wearing gloves to reduce the risk ofbloodborne pathogen infections.[37] Second, gloves are worn to reduce the likelihood that microorganisms present on the hands of personnel will be transmitted to patients during invasive or other patient-care procedures that involve touching a patient's mucous membranes and nonintact skin. Third, they are worn to reduce the likelihood that the hands of personnel contaminated with micro-organisms from a patient or afomite can transmit those micro-organisms to another patient. In this situation, gloves must be changed between patient contacts, and hands should be washed after gloves are removed.[citation needed]
Micro-organisms are known to survive on inanimate "touch" surfaces for extended periods of time.[38][39] This can be especially troublesome in hospital environments whereimmunodeficient patients are at enhanced risk for contracting nosocomial infections. Patients with hospital-acquired infections are predominantly hospitalized in different types of intensive care units (ICUs).[40]
Touch surfaces commonly found in hospital rooms, such as bed rails, call buttons, touch plates, chairs, door handles, light switches, grab rails, intravenous poles, dispensers (alcohol gel, paper towel, soap), dressing trolleys, and counter and table tops are known to be contaminated withStaphylococcus,methicillin-resistantStaphylococcus aureus (one of the most virulent strains of antibiotic-resistant bacteria) andvancomycin-resistantEnterococcus.[41] Objects in closest proximity to patients have the highest levels of methicillin-resistantStaphylococcus aureus and vancomycin-resistantEnterococcus. This is why touch surfaces in hospital rooms can serve as sources, or reservoirs, for the spread of bacteria from the hands of healthcare workers and visitors to patients.[42]
A number of compounds can decrease the risk of bacteria growing on surfaces including:copper,silver, andgermicides.[43]
There have been a number of studies evaluating the use of no-touch cleaning systems particularly the use of ultraviolet C devices. One review was inconclusive due to lack of, or of poor quality evidence.[44] Other reviews have found some evidence, and growing evidence of their effectiveness.[45][46]
Two of the bacteria species most likely to infect patients are theGram-positive strains ofmethicillin-resistantStaphylococcus aureus, andGram-negativeAcinetobacter baumannii. While antibiotic drugs to treat diseases caused by methicillin-resistantStaphylococcus aureus are available, few effective drugs are available forAcinetobacter.Acinetobacter bacteria are evolving and becoming immune to antibiotics, so in many cases,polymyxin-type antibacterials need to be used. "In many respects it's far worse than MRSA", said a specialist atCase Western Reserve University.[47]
Another growing disease, especially prevalent inNew York City hospitals, is the drug-resistant, Gram-negativeKlebsiella pneumoniae. An estimated more than 20% of theKlebsiella infections inBrooklyn hospitals "are now resistant to virtually all modern antibiotics, and those supergerms are now spreading worldwide."[47]
The bacteria, classified as Gram-negative because of their color on theGram stain, can cause severepneumonia and infections of theurinary tract, bloodstream, and other parts of the body. Their cell structures make them more difficult to attack with antibiotics than Gram-positive organisms like methicillin-resistantStaphylococcus aureus. In some cases, antibiotic resistance is spreading to Gram-negative bacteria that can infect people outside the hospital. "For gram-positives we need better drugs; for gram-negatives we need any drugs", said Brad Spellberg, an infectious-disease specialist atHarbor–UCLA Medical Center, and the author ofRising Plague, a book about drug-resistant pathogens.[47]
Hospital-acquired pneumonia (HAP) is the second most common nosocomial infection and accounts for approximately one-fourth of all infections in the intensive care unit (ICU).[48] HAP, or nosocomial pneumonia, is a lower respiratory infection that was not incubating at the time of hospital admission and that presents clinically two or more days after hospitalization.[49] Ventilator-associated pneumonia (VAP) is defined as HAP in patients receiving mechanical ventilation. The incidence of VAP is 10–30% among patients who require mechanical ventilation for >48 h.[50] A standard treatment protocol is based on accurate diagnosis definitions, microbiological confirmation of VAP, and the administration ofimipenem plusciprofloxacin as initial empirical antibiotic treatment.[51]
One-third of nosocomial infections are considered preventable. The CDC estimates 687,000 people in the United States were infected by hospital-acquired infections in 2015, resulting in 72,000 deaths.[52] The most common nosocomial infections are of theurinary tract, surgical site and variouspneumonias.[7]
An alternative treatment targeting localised infections is the use of irradiation by ultraviolet C.[53]
The methods used differ from country to country (definitions used, type of nosocomial infections covered, health units surveyed, inclusion or exclusion of imported infections, etc.), so the international comparisons of nosocomial infection rates should be made with the utmost care.[citation needed]
In Belgium, the prevalence of nosocomial infections is about 6.2%. Annually about 125,500 patients become infected by a nosocomial infection, resulting in almost 3000 deaths. The extra costs for the health insurance are estimated to be approximately €400 million/year.[54]
Estimates ranged from 6.7% in 1990 to 7.4% (patients may have several infections).[55] At national level, prevalence among patients in health care facilities was 6.7% in 1996,[56] 5.9% in 2001[57] and 5.0% in 2006.[58] The rates for nosocomial infections were 7.6% in 1996, 6.4% in 2001 and 5.4% in 2006.[citation needed]
In 2006, the most common infection sites wereurinary tract infections (30.3%),pneumopathy (14.7%), infections of surgery site (14.2%). Infections of theskin andmucous membrane (10.2%), other respiratory infections (6.8%) and bacterial infections / blood poisoning (6.4%).[59] The rates among adult patients inintensive care were 13.5% in 2004, 14.6% in 2005, 14.1% in 2006 and 14.4% in 2007.[60]
Nosocomial infections are estimated to make patients stay in the hospital for four to five additional days. Around 2004–2005, about 9,000 people died each year with a nosocomial infection, of which about 4,200 would have survived without this infection.[61]
Rate was estimated at 8.5% of patients in 2005.[62]
Since 2000, estimates show about a 6.7% infection rate, i.e. between 450,000 and 700,000 patients, which caused between 4,500 and 7,000 deaths.[63] A survey in Lombardy gave a rate of 4.9% of patients in 2000.[64]
Estimates range between 2 and 14%.[65] A national survey gave a rate of 7.2% in 2004.[66]
In 2012, theHealth Protection Agency reported the prevalence rate of hospital-acquired infections in England was 6.4% in 2011, against a rate of 8.2% in 2006,[67] withrespiratory tract,urinary tract andsurgical site infections the most common types of infections reported.[67] In 2018, it was reported that in-hospital infections had risen from 5,972 in 2008 to 48,815 in 2017.[68]
TheCenters for Disease Control and Prevention (CDC) estimated roughly 1.7 million hospital-associated infections, from all types of bacteria combined, cause or contribute to 99,000 deaths each year.[69] Other estimates indicate 10%, or 2 million, patients a year become infected, with the annual cost ranging from $4.5 billion to $11 billion.[70] In the US, the most frequent types of hospital infections are catheter-associated urinary tract infection (32%), followed by surgical site infection (22%), and ventilator-associated pneumonia (15%).[71]
In 1841,Ignaz Semmelweis, a Hungarianobstetrician was working at a Vienna maternity hospital. He was "shocked" by the death rate of women who developedpuerperal fever. He documented that mortality was three times higher in the ward where themedical students were delivering babies than in the next ward that was staffed bymidwiferystudents.[72] The medical students were also routinely working withcadavers. He compared therates of infection with a similar hospital inDublin, Ireland, andhypothesized that it was the medical students who somehow were infecting the women after labor. He instituted mandatoryhand-washing in May 1847 and infection rates dropped dramatically.Louis Pasteur proposed thegerm theory of disease and began his work oncholera in 1865 by identifying that it wasmicroorganisms that were associated withdisease.[73][74]
The dictionary definition ofnosocomial at WiktionaryAuthority control databases: National |
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