Nosocomial infection epidemiology and demographics
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]
Epidemiology and Demographics
Nosocomial infections are commonly transmitted when hospital officials become complacent and personnel do not practice correct hygiene regularly. Also, increased use ofoutpatient treatment in recent decades means that a greater percentage of people who are hospitalized today are likely to be seriously ill with more weakened immune systems than in the past. Moreover, some medical procedures bypass the body's natural protective barriers. Since medical staff move from patient to patient, the staff themselves serve as a means for spreading pathogens. Essentially, the staff act as vectors. 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.
United States
The Centers 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.[1] Other estimates indicate 10%, or 2 million, patients a year become infected, with the annual cost ranging from $4.5 billion to $11 billion. In the USA, the most frequent type of infection hospitalwide is urinary tract infection (36%), followed by surgical site infection (20%), and bloodstream infection and pneumonia (both 11%).
France
Estimates ranged from 6.7% in 1990 to 7.4% (patients may have several infections).[2] At national level, prevalence among patients in health care facilities was 6.7% in 1996,[3] 5.9% in 2001[4] and 5.0% in 2006.[5] The rates for nosocomial infections were 7.6% in 1996, 6.4% in 2001 and 5.4% in 2006. In 2006, the most common infection sites were urinary tract infections (30,3%), pneumopathy (14,7%), infections of surgery site (14,2%). Infections of the skin andmucous membrane (10,2%), other respiratory infections (6,8%) and bacterial infections / blood poisoning (6,4%).[6] The rates among adult patients in intensive care were 13,5% in 2004, 14,6% in 2005, 14,1% in 2006 and 14.4% in 2007.[7] Nosocomial infections are estimated to make patients stay in the hospital 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.[8]
Italy
Since 2000, estimates show about a 6.7% infection rate, i.e. between 450,000 and 700,000 patients, which caused between 4,500 and7,000 deaths.[9] A survey in Lombardy gave a rate of 4.9% of patients in 2000.[10]
United Kingdom
Estimates show a 10% infection rate,[11] with 8.2% estimated in 2006.[12]
Switzerland
Estimates range between 2 and 14%.[13] A national survey gave a rate of 7.2% in 2004.[14]
Finland
Rate were estimated at 8.5% of patients in 2005.[15]
Transmission
The drug-resistant Gram-negative bacteria, for the most part, threaten only hospitalized patients whose immune systems are weak. They can survive for a long time on surfaces in the hospital and enter the body through wounds, catheters, and ventilators.
| 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 host'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 {5 µm 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 include Legionella,Mycobacterium tuberculosis and the rubeola and varicella viruses. |
| Common vehicle transmission | This applies to microorganisms transmitted to the host by contaminated 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 other patient-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] |
Risk factors
Factors predisposing a patient to infection can broadly be divided into three areas:
- People in hospitals are usually already in a 'poor state of health', impairing their defense against bacteria – advanced age or premature birth along withimmunodeficiency (due to drugs, illness, or irradiation) present a general risk, while other diseases can present specific risks - for instance, chronic obstructive pulmonary disease can increase chances of respiratory tract infection.
- Invasive devices, for instance intubation tubes, catheters, surgical drains, and tracheostomy tubes, all bypass the body’s natural lines of defence againstpathogens and provide an easy route for infection. Patients already colonised on admission are instantly put at greater risk when they undergo invasive procedures.
- Patients' treatments can leave them vulnerable to infection – immunosuppression and antacid treatment undermine the body’s defences, while antimicrobial therapy (removing competitive flora and only leaving resistant organisms) and recurrent blood transfusions have also been identified as risk factors.
References
- ↑ Klevens, R Monina et al. "Estimating Health Care-associated Infections and Deaths in U.S. Hospitals, 2002." Public Health Reports 122.2 (2007): 160–166.
- ↑ Quenon JL, Gottot S, Duneton P, Lariven S, Carlet J, Régnier B, Brücker G. Enquête nationale de prévalence des infections nosocomiales en France : Hôpital Propre (octobre 1990). BEH n° 39/1993.
- ↑ Comité technique des infections nosocomiales (CTIN), Cellule infections nosocomiales, CClin Est, CClin Ouest, CClin Paris-Nord, CClin Sud-Est, CClin Sud-Ouest, avec la participation de 830 établissements de santé. Enquête nationale de prévalence des infections nosocomiales,1996, BEH n° 36/1997, 2 sept. 1997, 4 pp.. Résumé.
- ↑ Lepoutre A, Branger B, Garreau N, Boulétreau A, Ayzac L, Carbonne A, Maugat S, Gayet S, Hommel C, Parneix P, Tran B pour le Réseau d’alerte, d’investigation et de surveillance des infections nosocomiales (Raisin). Deuxième enquête nationale de prévalence des infections nosocomiales, France, 2001, Surveillance nationale des maladies infectieuses, 2001-2003. Institut de veille sanitaire, sept. 2005, 11 pp.Résumé.
- ↑ Institut de veille sanitaire Enquête nationale de prévalence des infections nosocomiales, France, juin 2006,Volume 1 – Méthodes, résultats, perspectives, mars 2009, ii + 81 pp. 2 – Annexes, mars 2009, ii + 91 pp.Synthèse des résultats, Mars 2009, 11 pp.
- ↑ Institut de veille sanitaire Enquête nationale de prévalence des infections nosocomiales, France, juin 2006, Vol. 1, Tableau 31, p. 24.
- ↑ Réseau REA-Raisin « Surveillance des infections nosocomiales en réanimation adulte. France, résultats 2007 », Institut de veille sanitaire, Sept. 2009, ii + 60 pp.
- ↑ Vasselle, Alain « Rapport sur la politique de lutte contre les infections nosocomiales », Office parlementaire d'évaluation des politiques de santé, juin 2006, 290 pp. (III.5. Quelle est l’estimation de la mortalité attribuable aux IN ?).
- ↑ L'Italie scandalisée par "l'hôpital de l'horreur", Éric Jozsef, Libération, January 17, 2007 Template:Fr
- ↑ Liziolia A, Privitera G, Alliata E, Antonietta Banfi EM, Boselli L, Panceri ML, Perna MC, Porretta AD, Santini MG, Carreri V. Prevalence of nosocomial infections in Italy: result from the Lombardy survey in 2000. J Hosp Infect 2003;54:141-8.
- ↑ Aodhán S Breathnacha, Nosocomial infections, Medicine, 2005: 33, 22-26
- ↑ Press release forThe Third Prevalence Survey of Healthcare-associated Infections in Acute Hospitals. Hospital Infection Society, Londres, 27/10/06.
- ↑ Facts sheet - Swiss Hand Hygiene Campaign. (.doc)
- ↑ Sax H, Pittet D pour le comité de rédaction de Swiss-NOSO et le réseau Swiss-NOSO Surveillance.Résultats de l’enquête nationale de prévalence des infections nosocomiales de 2004 (snip04). Swiss-NOSO 2005;12(1):1-4.
- ↑ Lyytikainen O, Kanerva M, Agthe N, Mottonen T and the Finish Prevalence Survey Study Group. National Prevalence Survey on Nosocomial Infections in Finnish Acute Care Hospitals, 2005. 10th Epiet Scientific Seminar. Mahon, Menorca, Spain, 13–15 October 2005 [Poster].
- ↑ Jain SK, Persaud D, Perl TM; et al. (2005). "Nosocomial malaria and saline flush". Emerging Infect. Dis. 11 (7): 1097–9. PMID 16022788. Unknown parameter
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