subject: Nosocomial infection [print this page] Nosocomial infection Nosocomial infection
Hospital patients may be particularly susceptible to infectionand hospital bacteria are often resistant to commonantibiotics. Susceptibility is increased in postoperativepatients, patients with bums, patients on ventilators, inmalnourished patients, and in disease states that compromiseimmunity specifically. Hospital-acquired infectionsare known as nosocomial and are a particular problem onintensive treatment units. Nosocomial infection is anincreasing problem and the resistance pattern of bacteriais constantly changing. The most important factors influencingthe likelihood of cross-infection are the use of handwashing,the ratio of nurses to patients, the number of visitsfrom doctors and the space between patients.The bacteria associated with particular situations cansometimes be predicted, e.g. staphylococci and streptococciare common causes of surgical wound infections,and Pseudomonas frequently infects burns. In ventilatedpatients difficulties arise in deciding whether bacteria suchas Pseudomonas are merely colonizing the respiratorymucosa or whether they are pathogenic. Antibiotic treatmentof colonising organisms is undesirable since the localflora then change to more resistant organisms.With increasing use of antibiotics there has been a resurgenceof outbreaks of nosocomial infection with methicillin(and flucloxacillin)-resistant Staphylococcus aureus(MRSA). MRSA colonize the skin and nose of normal ordiseased subjects, but they are particularly persistent inpatients with any form of skin lesion. In most cases MRSAdo not cause disease, but occasionally vulnerable patientscan develop septicaemia or local suppuration which necessitatesthe use of vancomycin. Because MRSA spreadsrapidly from person to person it is important to isolateinfected patients from other vulnerable patients, and toscreen staff for carriage. Colonized subjects are treatedwith topical antiseptic preparations and, in the case of staff,removed from work until repeated swabs are clear.Vancomycin-resistant staphylococci have been isolatedand the increasing use of this antibiotic has led to aproblem with resistant enterococci. There is some evidencethat antibiotic cycling in intensive care units - that is,changing the first-choice antibiotics every few months -limits the rate of increase in resistance among commonnosocomial bacteria. For example, resistance to gentamicinin enterobacteriaceae such as Klebsiella pneumoniae andSerratia marcescens increases when gentamicin is used, butdecreases when amikacin is substituted. However, there isno consensus on the best policy at present.The use of antibiotics must be controlled both in hospitalsand in the community. Most hospitals have antibioticcontrol policies which recommend the antibiotic to beused in a particular situation and restrict the administrationof some drugs to special situations. Policies for antibioticprophylaxis before surgery need to be reviewedregularly to keep ahead of the development of bacterialresistance.CONTROL OF INFECTIONContainment of outbreaks of infection is required whensusceptible subjects may develop a serious illness if theybecome infected. It is not always desirable to contain infection.Chickenpox, a mild disease in normal children, isusually severe in adults and so outbreaks among schoolchildrenshould not be controlled. In a hospital wherenon-immune patients are liable to develop severe manifestations,however, it is important to prevent crossinfectionto non-immune individuals (about 10% of theadult population).Isolation of patients in single rooms greatly facilitatescontrol of infection. Other measures are determined by themode of transmission and the degree of infectivity of theorganism. Transmission is by: Respiratory secretions (e.g. measles, pulmonarytuberculosis) Excretions and secretions (e.g. gastroenteritis, hepatitisA, typhoid) Skin contact and fomites (e.g. MRSA).Respiratory transmission can be prevented by having thepatient and/or the attendants wear appropriate masks.Organisms transmitted in respiratory secretions usuallyinfect others through the upper or lower respiratory tract,and gowning and handwashing are of minor importance.When excretions and secretions are infectious the mostimportant containment measure is handwashing. Whenclose contact is necessary with a highly infectious patient,such as a patient excreting Shigella in the faeces, gowns andgloves are worn. Special arrangements are needed for thedisposal of excreta, contaminated dressings and contaminatedclothing and bedding.When microorganisms are found in significant numberon the skin, in fomites and in dust around the patient, aswhen MRSA colonize patients in hospital, additional precautionsmust be taken, including the use of overshoestogether with gowns and gloves. Notification also allows surveillance of the incidenceof these infections. Most patients have ceased to bean infectious risk by the time they are discharged fromhospital, but intestinal pathogens often remain in the stoolsfor several weeks. Carriers of such pathogens are advisedto avoid handling food for others, to wash hands regularlyand to avoid towel sharing. Following notification, stoolsamples will be checked by the local authority until theyare pathogen free. http://www.articlesbase.com/diseases-and-conditions-articles/nosocomial-infection-2787959.html
