Nosocomial infection

Nosocomial infection

Hospital acquired infections
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An infection occurring to a patient in hospital or other health care facility in whom it was not present or incubating at the time of admission or the residual of an infection acquired during a previous admission .
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Includes: infection acquired in the hospital but appearing after discharge & also infections among the staff of the facility Occurs at rate of approximately 5-10% admission in some hospitals Many nosocomial infections are associated with an : Extended length of stay Substantial morbidity & Prolonged therapy

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if medical staff are not adequately trained &guidelines not well developed &monitored, this will increase Nosocomial infection.  
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Descriptive epidemiology Agent host Environment Agent factors: Pathogenicity &virulence Invasiveness &toxicity Tissue selectivity Antigenicity Viability Dosage of the infection
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 COMMON BACTERIAL AGENTSAGENTS

(9%)
(10%)
(11%)
(12%)
(13%)
(45%)



Host factors: Resistance &immunity Genetic factors Physiological factors Age &sex Social &habitual factors Environmental factors : Physical Biological Socio-cultural Economic Epidemiological Triangle

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Diagnostic procedures , medical or surgical therapy ..it can cause.. infection Potent immunosuppressive ,chemotherapeutic agents &antibiotics affect normal flora Exposure to persons who are infected or carriers can transmit inf. (health workers or patients)
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Infection rate differ considerably among hospitals Referral hospitals generally have higher rate than community hospitals: (More complex patient mix &more aggressive modes of therapy used)
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General risk factors of NI within the hospital include : Prolonged stay (>/ 48hrs) Mechanical ventilation Diagnosis of trauma Urinary catheter
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Prevention (general outbreaks): Investigation of reservoir &mode of transmission Appropriate use of diagnostic procedures ,invasive devices &medical therapy particularly antibiotics Hospital environment may be modified Strategies to proper use of isolation materials hand washing ,&other effective approaches to prevent transmission .
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Main categories of Nosocomial infection

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1.Urinary Tract Infection: IT accounts 1/3 of NI 80% of NUTIs caused by urinary catheters The typical UTIs prolongs hospital stay The prevalence of bacteruria during a short term use of catheter is: approximately 15% compared with a prevalence of 90% in along term use
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Risk factor for bacteruria: Duration of catheterization Micro bacterial colonization of the drainage bag No antibiotic use Female gender Diabetes mellitus Abnormal serum creatinine Errors in catheter care
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Prevention a. Prevention of catheterization by the use of alternative approach Patient training Medication Surgery Use of special clothes &bags Intermittent catheterization Use of external collection &urinary diversion
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b. Prevention of bacteruria once catheterized minimizing the duration recommended closed drainage systemGood hand washing after caring each patient is the single measure most –likely to prevent cross-transmission of urinary pathogens *

2.Lower respiratory infection (LRI) &pneumonia It accounts >13% of NIs CFR 20-50% N pneumonia associated with an excess length of stay of >/one week Most of NLRI occur in ICU &surgery recovery units
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Predisposing factors Endotracheal intubations Tracheostomy (lead to decrease LRT defense mechanisms ..drying and direct rout of entry) Ventilator Contaminated aerosols Other contaminated equipment Chronic lung diseases Advanced age prior administration of antibiotics Immunosuppression.

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Prevention General hygienic measures Use of barrier isolation materials Routine decontamination of respiratory equipments Using gloves ,gowns &masks Annual influenza immunization of pts &hospital staff
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3.Surgical wound infections (SWIs) sWIs are now the 2nd most common NI accounting for at least 17% Infection rate varies according to: operative site patient co morbidity
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Sources :Inoculation from pt’s residual floraContaminated host tissues Surgical team members hands at the time of surgeryAirborne contamination at the time of surgery Post operative drains or catheters *

Prevention: Not shaving the operation site with a razor Disinfection of the skin at the incision site Appropriate use of preoperative antibiotics when indicated Perioperative antibiotics started immediately before surgery &continued for up to 24 hrs after are effective
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4.Nosocomial Diarrhea: A common problem Risk factors Older age sever underlying disease Hospitalization of more than one week Long stay in the ICU Prior antibiotic treatment.

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5.Blood stream infection (BSIs) Account for 14% of NIs Primary bacteremia: isolation of bacterial blood stream pathogen in the absence of an infection at another site Secondary bacteremia: occurs when bacteria are isolation from the blood during an infection with the same organism at another site : i.e UTIs, SWIs, LRIs
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Source: 1-IV catheters , intrinsic IV fluid contamination ,multi dose parenteral IV medications 2-Contamination of antiseptics 3-Contamination of hands of health workers 4-External colonization of the catheter
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AnthraxIt is an acute bacterial disease that usually affects skin but may very rarely involve oropharynx, mediastinum, or intestinal tract.
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A/Cutaneous Anthrax Presented with itching of an exposed skin followed by papular then vesicular lesion which within (2-6)days proceed into a depressed black Escher with extensive edema. usually it is painless.
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Cutaneous Anthrax

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B/Inhalation Anthrax Presented initially with mild nonspecific symptoms (flulike) followed by acute symptoms of respiratory distress with x-ray evidence of mediastinal widening, fever and shock within (3-5)days with death shortly thereafter. C/Intestinal Anthrax It is rare and difficult to recognize. Abdominal distress followed by fever, signs of septicemia and death.
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*Diagnosis: is made by determination of the causative agent in blood , lesions or discharges by direct polychrome methylene blue stained smears or by culture or inoculation of mice, guinea pigs or rabbits. ELISA may be available in certain laboratories . *Infectious agent: Bacillus Anthracis (gram positive, encapsulate, spore forming non motile rods).
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Occurrence : Human is an incidental host. Sporadic infrequent human infections in most industrialized countries. Endemic in agricultural regions. *It is an occupational hazards primarily of :- 1.Workers with animal hair, bone, and wool processing. 2.Veterinarians and agriculture and wild life workers.
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*Anthrax is considered a leading potential agent in biowarfare and as such could present in epidemiologically unusual circumstances . Reservoir: Animals shed bacilli in terminal hemorrhages or blood at death. On exposure to air, vegetative cells sporulate, the spores are resistant to adverse environmental conditions and disinfections. It may remain viable in soil for many years.
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Mode of transmission : *Cutaneous infection is by : 1.Contact with tissues of animals dying of the disease .Possibly by fly bite. 2.Contact with hair, and wool or products. 3.Contact with contaminated soil . *Inhalational type through inhalation of spores in risky industrial processes (wool). *Intestinal and or pharyngeal is through ingestion of undercooked contaminated meat.
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Incubation period : (1-7) days ( may be up to 60 days). Period of communicability : Person to person transmission is very rare. Articles and soil contaminated with spores may remain infective for decades. Susceptibility and resistance: Uncertain ,there is some evidence of inapparant infection among people in frequent contact with infectious agent. Second attack can occur but rare.
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Preventive Measures :1.Immunize high risk persons with a cell –free vaccine containing protective antigen. 2.Eduacte employees about mode of transmission, care of skin abrasions and personal cleanliness.3.Control dust and properly ventilate work areas.4.Thoroughly wash, disinfect or sterilize hair, wool, and bone meal. *

5.If anthrax is suspected in animals aseptically collect blood sample for culture then autoclave, incinerate, or chemical disinfection of all instruments or materials used. 6. Promptly immunize and annually reimmunize all animals at risk.
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