Outline the aetiology, clinical manifestations and possible preventative measures for nosocomial infections in Intensive Care.
Aetiology: dependent on cause. Combination of overgrowth of endogenous flora, immune suppression, impairment of natural defences (eg. endotracheol tube, invasive catheters), and cross contamination with pathogens. Commonest are pneumonia (thought related to aspiration of organisms colonising oro-pharyngeal and gastric contents, decreased gastric pH, exposure to water borne organisms), surgical wound infections (contamination at time of surgery), sinusitis (tubes, immobility, nasal congestion), line related sepsis (entry site contamination, blood borne contamination, contamination of intravenous lines).
Clinical manifestations: apart from systemic manifestations of sepsis (leukocytosis/leukopaenia, fever, etc) are dependent on cause. Pneumonia (purulent secretions, impaired oxygenation, radiological infiltrates etc.), sinusitis (purulent discharge), line related (local inflammation). Diagnostic techniques are specific to cause.
Possible prevention: consider general infection control measures (including surveillance, continuous quality improvement, avoid un-necessary immunosuppression [steroids, glucose control], avoid un- necessary antibiotics). Decrease cross infection (standard precautions [esp. hand washing] and transmission based precautions; cleaning/disinfection and sterilization of equipment; avoiding reuse of single use items). Pneumonia (eg. semi-recumbent position, aspiration above cuff, possibly selective decontamination, infrequent changing of circuit). Line related (eg. sterile insertion, antibiotic/antiseptic impregnated lines, perhaps tunneling, surveillance, change according to protocol).
This question is painfully broad. A good article reporting on the epidemiology of nosocomial infection in American ICUs is available, and using this substrate, one can attempt to boil the answer down into a point-form list. A notable reference is Hatcher and Dhillon's chapter for Ohs' Manual(Ch 70, p. 724)
Aetiology of nosocomial infection in ICU:
Chapter 70 (pp. 724) Nosocomial infections by James Hatcher and Rishi H-P Dhillon
Ak, Oznur, et al. "Nosocomial infections and risk factors in the intensive care unit of a teaching and research hospital: A prospecive cohort study." Medical Science Monitor 17.5 (2011): PH29-PH34.
Barnett, Adrian G., et al. "The increased risks of death and extra lengths of hospital and ICU stay from hospital-acquired bloodstream infections: a case–control study." BMJ open 3.10 (2013): e003587.
Doyle, Joseph S., et al. "Epidemiology of infections acquired in intensive care units." Seminars in respiratory and critical care medicine. Vol. 32. No. 02. © Thieme Medical Publishers, 2011.
Richards, Michael J., et al. "Nosocomial infections in combined medical-surgical intensive care units in the United States." Infection control and hospital epidemiology 21.8 (2000): 510-515.
Lepape, A. "Prevention of nosocomial infections in ICU. What is really effective?." Medicinski arhiv 57.4 Suppl 1 (2002): 15-18.