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Nosocomial infections (34 cards)
Nosocomial infections هەوکردنی نەخۆشخانەکان
prevention & control methods
definition
> Nosocomial infection: An infection that occurs 48 to 72 hours after admission to the hospital or within a specified period (10-30 days) after discharge, provided that بە مەرجێک کە… at the time of admission there are no obvious signs نیشانە دیارەکان of infection and the disease has not been in its incubation period.
> Microbial infections that appear in the first 48 hours of a patient’s hospitalization are considered دادەنرێت community-acquired infections.
> Nosocomial infections can be acquired from the environment or caused by the patient’s internal flora.
> The World Health Organization (WHO) has recently replaced the HAI (Hospital Acquired Infections) with HCAI (Health Care Acquired Infections) to highlight the importance of infection control out of the hospital environment.
Reasons for the importance of nosocomial infections
> Increase the length of stay of the patient in the hospital
Increases hospital costs for the patient.
Missed working days of patients
Reducing the quality use of hospital beds
Increased risk of personnel infection
Factors contributing to nosocomial infections (susceptibility ئامادەیی and resistance)
In-patients are more susceptible and less resistant to infection than the healthy population. Some reasons:
> Existence of underlying disease
Use of immunosuppressive drugs, antibiotic therapy, etc.
Elimination نەهێشتنی of the body’s natural defense barriers (skin damage following injections, change in body flora following antibiotic therapy, etc.)
Increasing the number of invasive داگیرکەرەکان technical medical methods
Drug-resistant bacteria in hospitalized patients
Complex and long-term surgeries
Density of patients in the hospitals
Intensive care units یەکەکانی چاودێری چڕ , burns, oncology, organ transplants and stem cell transplants are more susceptible زیاتر ئامادەن to infection than other departments.
where do the microbes come from?
> patient’s own flora
cross infection from medical personnel
cross infection from patient to patient
hospital environment ( inanimate objects):
air
water
dust
IV fluids & catheters
washbowls
bedpans
endoscopes
ventilators & respiratory equipment
sources of infection
endogenous:
> patients own flora may invade patient’s tissue during some surgical operations or instrumental manipulations
> normal commensals of the skin, respiratory , GI, UG tract
exogenous:
>from another patient , staff member , environment in the hospital
> environmental sources: inanimate objects, air, water, food
> cross infection from: other patients, hospital staff(suffering from infections or asymptomatic carriers)
Necessary conditions and factors to cause nosocomial infection
Three elements must be provided to transmit the infection in the hospital:
1- Source of infectious organisms: patients, personnel, sometimes visitors and objects
2- Susceptible host
3- Transmission route: common tools, airway, vector (mosquitoes and flies)
(Reservoirs) Source of infectious organisms
> It is the place where the infectious agent can survive, grow and multiply and wait for it to be transmitted to the susceptible host.
Common reservoirs of infection include humans, animals, plants, soil & water.
Common reservoirs of infection in the hospital are: patients, medical personnel, equipment and environment
Measures to reduce nosocomial infection reservoirs
> Patient bathing: Using soap and water to clean and remove discharge, drainage, sweat, or sediment from patients
Dressing materials: Change periodically and at the appropriate time contaminated and wet dressings
Contaminated needles: Insert syringes and cap-free needles into perforated-resistance containers (safety box).
Contaminated material: Use of impermeable bags
Cleaning surfaces: Cleaning and drying table surfaces near the patient’s bed with appropriate detergents and disinfectants
Surgical Wounds: Keep drainage tubes and drainage bags open
Drainage containers and bags: Regular replacement of drainage containers, the drainage system should be located at a lower level than the drainage site.
microorganisms
> any pathogen, on occasion, can cause HAI
those that are able to survive in hospital invironment & develop resistance to antibiotics & disinfections: major cause
commensal bacteria: found in the normal flora of healthy people.
signifivant protective role by preventing colonization by pathogenic microorganisms.
some commensal bacteria may cause infection if the host is compromised.
eg. staphylococcus epidermidis ( cause of I.V. infection)
escherichia coli (cause of urinary infections).
pathogenic bacteria: they have greater virulence , and cause infections( spordic or epidemic) regardless of host status .
Bacteria:
most frequent (up to 80%) of nosocomial infectious agents. About 25 to 50 percent of all nosocomial infections are Gram-negative and 10 percent are Staphylococcal infections.
bacteria:
1\ gram positive bacteria
2\ gram negative bacteria
1\ gram positive bacteria
> staphylococus aureus:
bacteria that colonize the skin, nose and throat of patient and hospital staff. they cause a wide variety of lung , bone , heart and bloodstream infections and are frequently resistant to antibiotics.
in hospitals commonly 40+50% of s.aureus isolates are MRSA.
staph epidermidis & group D streptococci
streptococci: streptococcus hemplyticus & streptococcus pyogenes
clostridium tetani spores: survive in dust for very long time
2\ gram negative bacteria
> in recent decades , enteric gram negative bacilli -> most important group of hospital pathogens
enterobacteriaceae:
( e.coli, proteus, klepsiella, enterobacter, serratia) may colonize sites when the host defences are compromised. they may also be highly antibiotic resistant.
pseudomonas spp:
-often isolated in water and damp areas. they may colonize the digestive tract of hospitalized patients.
- ability to survive & multiply at low temp
- resistance toward antibiotics & disinfectants
viruses:
> HIV and Hepatitis B & C viruses :
transmitted through blood & blood products
viral diarrhea & chickenpox can be spread in hospitals
. cytomegalovirus, herpes virus, influenza , enteroviruses & arenaviruses can cause HAI
*Viral nosocomial infections are more important in children and infants, the elderly and those with chronic diseases.*More than 90% of viral hospital infections are respiratory and digestive viruses.
fungi:
candida albicans , aspergillus , mucor
Fungal infections in the hospital have increased significantly during the last decade.*These infections are often opportunistic.
protozoa:
entamoeba histolytica , plasmoida , toxoplasma gondii , pneumocystis carinii
Parasites, like fungi, are opportunistic and often develop after long-term antibiotic treatment or a weakened immune system.
Modes of transmission
A-Contact transmission
B- Non-contact transmission
A-Contact transmission: The most common way of transmission is nosocomial infection.
*Direct contact: The possibility of transmitting the infection is higher than indirect contact, but in practice it is less important in transmitting the infection between patients. Conversely, it is very important in transmitting infection between staff and patients. Example: MRSA and influenza
*Indirect contact: The most common way of transmitting nosocomial infections, through contamination of surfaces and objects, etc. The role of hospital staff in indirect transmission and contamination of clothing, patient sheets, needles, surgical supplies, etc. is very important.
*Contact with micro droplets: Large particles (more than 5 microns) released from the respiratory mucosa that are dispersed up to a distance of 1 meter. Discharge suction, bronchoscopy, chest physiotherapy can lead to the spread of droplets. Influenza, the coronaviruses that cause COVID- 19, and SARS, Mycoplasma, Streptococcus A, and Neisseria meningitis are transmitted this way.
B- Non-contact transmission:
*Airborne transmission: by inhalation of droplet nuclei (less than 5 microns). TB bacillus, rubella virus, and varicella zoster and Aspergillus fungi are spread this way.
*Transmission from inanimate carriers: includes infections transmitted through food, water and blood products
*Transmission through living vectors: Transmission of infectious agents through mosquitoes, insects, mice and other rodents is not an important route of transmission in many countries, including Iran.
General epidemiology of nosocomial infections
The four most common and important types of nosocomial infections (80% of nosocomial infections) are:
Urinary tract infections
Surgical site infections
Respiratory infections
Blood infection
Other Nosocomial Infections: These include many areas prone to infection that can lead to nosocomial infections if the right context is provided, for example:
Open wounds (ulcers, burns and pressure sores): facilitate the accumulation of bacteria and cause systemic infection
Gastrointestinal inflammation: The most common nosocomial infection in children (rotavirus is a major pathogen). Clostridium difficile is the leading cause of nosocomial gastrointestinal inflammation in adults in developed countries
Inflammation of the sinuses and other internal infections, eye infections and conjunctivitis
Inflammation of the endometrium and other infections of the genitals following the birth of a baby
common nasocomial infections
> UTI:
- most common HAI (%40 of nosocomia infections)
- usually associated with catheterization or instrumentation of urethra , bladder or kidneys
- e.g\ e.coli , klebsiella , proteus , serratia , pseudomonoas , candida albicans
> pneumonia (respiratory infections):
- leading cause of mortality in patients suffering from HAI
- during aspiration in unconscious patients & pulmonary ventilation
-e.g\ staph.aureus , klebsiella , enterobacter , serratia , proteus , pseudomonas , acinetobacter , legionella , e.cole
> wound & skin sepsis:
- follow surgical procedure where causative agent are introduced into the tissue during operations
- higher in elderly patients
- manifest within a week of surgery
- non-surgical wounds due ti burns bed sores.
-e.g\ staph aureus , pseudomonas aeruginosa , e.coli , proteus , enterococci
> gastrointestinal infections:
- food poisoning due to salmonella, shigella sonnei
- enterotoxic manifestation due to staphylococcal contamination of cooked food
- diarhhea due to e.coli
