Nosocomial Infections
Nosocomial infection is the other name of ‘’Hospital-acquired infection.’’ It can be define as:
‘’The infection acquired by the person in the hospital, manifestation
of which may occur during hospitalization or after discharge from
hospital. The person may be a patient, members of the hospital staff
and/ or visitors.’’
“ Nosocomial ”originate from Two Greeks words :
“nosus” meaning “disease”
“komeion” meaning “to take care of.”
Hence, “Nosocomial” mean any disease contracted by a patient while under medical care , Hospital environment , clinic , rehabilitation facility, nursing home environment,, or other clinical settings.
Nosocomial Infections: Changing Microbiology
Mid-1980’s Mid-1990’s
Enterobacteriaceae Decline in Enterobacteriaceae
S. Aureus Increase in gram-positive cocci
P. Aeruginosa Emergence of fungi
Recognition of viruses
Source of infection:
There are many direct or indirect source of this infection
as given below:
1.Endogenous
2.Exogenous
Endogenous:
This is direct source of infection caused by organisms
that are present as a part normal flora of patient.
Exogenous:
This is indirect source of infection caused by exposure to hospital environment , cross infection from medical personal. Contaminated surface and environment increase cross transmission e.g
Air & Dust
IV fluids & Catheters
Wash bowls & Bed pans
Endoscope
Ventilator and respiratory equipment & Water Disinfectants etc
Cause:
Nosocomial infections are caused by almost all type of micro-organisms e.g Bacteria, Viruses, Fungi, Parasite.
1.Bacteria
Gram +ve bacteria:
Staphylococcus aureus (Methicillin resistant)
Clostridium difficile
Staphylococcus epidermidis
Gram -ve bacteria:
Enterobacteriaceae
Pseudomonas aeruginosa
Acinetobacter baumanni
Mycobacterium tuberculosis
Escherichia coli
Stenotrophomonas maltophilia
2. Viruses
Blood borne infections : HBV, HCV, HIV◦
Others: rubella, varicella, SARS
3. Fungi
Candida albicans
Aspergillus
Types of Nosocomial infections:
Surgical wound infections (SWI)
Lower respiratory infections
Traumatic wounds and burns infections
Primary bacteraemia
Gastrointestinal tract
Hospital-acquired pneumonia
Ventilator-associated pneumonia
Urinary tract infection
Gastroenteritis
Puerperal fever
Central nervous system
Mode of transmission:
1.Contact (most common):
Direct (physical contact) by Hands,clothing ,Droplet contact(followed by auto inoculation) Clinical equipment
Indirect via contaminated articles,Bedpans,bowls,jugs,Instruments like needles,dressings, contaminated gloves,etc.
2.Droplet Transmission:
Droplets containing microbes are also the source of Nosocomial infections .
Droplets are generated by source patient by coughing, sneezing, and talking, and during the performance of certain procedures, such as bronchoscopy.
3. Airborne Transmission:
Some microbes are suspended in air and dust particle can cause Nosocomial infections.
For example Legionella, Mycobacterium tuberculosis and the rubeola and varicella viruses are transmitted by airborne transmission.
By inhalation of infectious particles Nosocomial infections occur ( TB,Varicella)
4. Oral route
Through Gastro Intestinal Tract (GIT)
By food, water, medications etc
5. Parenteral route:
Through injectible , parentral solutions
6. Vector borne:
Through mosquitoes, flies, rats
7. Pathogens transmission:
Pathogen transfer directly(e.g by hands) , indirectly(e.g by food) or by any vector
Signs & Symptoms:
Different Nosocomial infections have different signs or symptoms e.g. abscesses, Discharge, fever, and inflammation. Severe pain and irritation at the infection site and many other visible symptoms may occur.
Prevention & control of Nosocomial infections
Sterilization:
1.Sterilization should be done before sanitizing.
2.Various institutional methods such as air filtration within the hospital should be practiced.
3.Through exposure to chemicals, ionizing radiation, dry heat, or steam under pressure , all microorganisms on equipment and surfaces could be killed.
Isolation:
To prevent the microorganism’s transmission by common routes in hospital and to protect patients, visitors, and Health care workers from Nosocomial infection isolated precaution should be practiced.
Hand washing:
To reduce the risks of transmitting skin microorganisms Hand-washing is a good and common practice.
Gloves:
Use of gloves reduce the risk of microorganism transmission.
Surface sanitation:
Modern sanitizing methods should be used , such as Non-flammable Alcohol Vapor in Carbon Dioxide systems have been effective against influenza MRSA, and gastroenteritis , for sanitizing surface.
Against endospore-forming bacteria, such as Clostridium difficile , Hydrogen peroxide is very effective.
Proper Surveillance:
Surveillance for common infections, prevalence rate of specific infections and set goal for improvement , monitoring of high risk patients, and hospital area to identify outbreaks and document incidence.
Diagnosis
All bacterial or fungal growth on a culture is not pathogenic. Such growth may reflect simple microbial colonization. Following interpretation should be given to the patient:
1.Clinical presentation of the patient
2.Reason for obtaining the test
3.Process by which the specimen was obtained
4.Presence or absence of other supporting evidence of infection
Following methods are used to diagnose and characterize a Nosocomial infection:
1.Quantitative culture of blood obtained from the catheter and peripheral vein.
2.Suspected fungal inspection: fungal cultures
3.Possible thrombosis or propagation: Imaging studies such as echo cardiography
4.Immunocompromised patients;
Occasional special studies (e.g., cultures for atypical Mycobacteria)
e.g tests used to identify pneumonia include the following:
Acute phase reactants
Oxygen saturation and hemodynamic studies
Chest radiography
Sputum Gram stain and culture (if necessary, samples can also be obtained through bronco-alveolar lavage or thoracocentesis)
In specific cases Rapid diagnostic tests should be performed.
Treatment of Nosocomial infections
Most common bacteria that infect the patient are MRSA (resistant strain of S. aureus), member of gram-positive bacteria and Acinetobacter (A. baumannii), which is gram-negative.
While antibiotic drugs are available to treat diseases which are caused by gram-positive MRSA , few effective drugs are available for Acinetobacter. Some bacteria are evolving and becoming immune to existing antibiotics such as Acinetobacter , in such cases need to use polymyxin-type antibacterials.
Drug-resistant gram-negative Klebsiella pneumoniae is another growing disease. More than 50% of the Klebsiella infections are now resistant to virtually all modern antibiotics, and those super-germs are now spreading worldwide.
Gram negative bacteria can cause severe pneumonia and infections of the urinary tract, bloodstream, and other parts of the body. Their cell structures make them more difficult to attack with antibiotics than gram-positive organisms like MRSA. In some cases, antibiotic resistance is spreading to gram-negative bacteria that can infect people outside the hospital.
Dr. Brad Spellberg, an infectious-disease specialist said that for gram-positives we need better drugs; for gram-negatives we need any drugs.
One-third of Nosocomial infections are considered preventable. The CDC noticed that 8 million people in world are infected every year by hospital-acquired infections, resulting in 80,000 deaths. The urinary tract infection , infections at surgical site and various pneumonia are the most common Nosocomial infections.
References:
1.https://en.wikipedia.org/wiki/Hospital-acquired_infection
2.http://www.healthline.com/health/hospital-acquired-nosocomial-infections
3.http://www.medicinenet.com/script/main/art.asp?articlekey=4590
4.http://emedicine.medscape.com/article/967022-overview
5.http://ceaccp.oxfordjournals.org/content/5/1/14.full
6.http://ceaccp.oxfordjournals.org/content/5/1/14/T1.expansion.html
7.http://ceaccp.oxfordjournals.org/content/5/1/14/T2.expansion.html