Day 9: Nosocomial Infections

What is nosocomial infection? And why is it important for us to know?

Let’s start with familiarising ourselves with the meaning of nosocomial infection.

Nosocomial infection (NI) or also known as hospital-acquired infection is an infection acquired in the hospital by a patient who was admitted for a reason other than that infection. This infection is not present in the patient at the time of admission to the hospital but it developed during the course of stay in the hospital. This infection includes the occupational infections among staff in the hospital.

There are 2 main forms on NI; endogenous infection and exogenous infection.

1. Endogenous infection, or also known as self-infection or auto-infection is the infection developed during the stay in the hospital. The causative agent comes from the patient (normal flora or colonisers of skin and other epithelial surfaces) and it infected the patient due to their decrease immunity.

2. Exogenous infection can be further divided into 2 type; cross-infection and environmental infection. It can come from another person or an environmental source.

• Cross-infection – the patient comes into contact with new infective agents and develops infection

• Environmental infection – the organism acquired depends on the nature of the source. For example; moist areas tend to be colonized with Gram-negative rods (eg: Escherichis coli, Klebsiella, Psedomonas) whereas air and dust-borne organisms are those that can withstand drying (eg: streptococci, staphylococci, mycobacteria, acinetobacter). Other sources can come from food, in fluids catheters, endoscope, ventilator and respiratory equipment, and etc.

Factors influencing the development of NI:

• The microbial agent
• Patient susceptibility
• Environmental factors
• Bacterial resistance

Virtually all microorganisms can cause NI:

• Virus 
• Blood-borne: HIV, HBV, HCV
• Others: CMV, rubella, varicella
• Bacteria
• Gram-positive (eg: staphylococcus aureus, staphylococcus epidermidis)
• Gram-negative (eg: enterobacteriaceae, pseudomonas aeruginosa, acinetobacter baumanni)
• Mycobacterium tuberculosis
• Fungi
• Candida
• Aspergillus
• Parasite

Types of infection:

• Urinary tract infections [most common!]
• Surgical wounds infections (surgical site infections)
• Nosocomial respiratory infections
• Infection with intravascular lines
• Primary bacteraemia

The impact of NI:

1. Patients:

• Increase LOS (Length of Stay) and treatment course
• Increase cost
• Possible to get another disease and maybe even more dangerous
• Increase GDR (Gross Death Rate)

2. Hospital:

• Overload
• Increase workload
• Increase operational cost
• Unsafe during duty (can cause operational infection)
• Possible cause of malpractice
• Decrease hospital quality

3. Community

• Absent for job (thus decrease human resources)
• Source of transmission to their family and community

NI caused many kinds of problems to the patient, hospital and the community. Therefore, it is important for us to do something about this.

“Prevention is better than cure”

1/3 of NI is preventable!

How do we do this?

• Separate the source of infection from the rest of the hospital
• Cut off any route of transmission

What other ways to prevent NI?

Reducing person-to-person transmission through:

• Hand washing
• Personal hygiene
• Clothing
• Mask
• Gloves
• Safe injection practices

Preventing transmission from the environment through:

• Cleaning of the hospital environment
• Use of hot/superheated water
• Disinfection of patient equipment
• Sterilization

“Hand washing is the single most important measure for control of NI”

Hand hygiene, including hand washing and hand disinfection, is the primary preventive measure. Thorough hand washing with adequate quantities of water and soap removes more than 90% of the transient flora including most contaminants. An antimicrobial soap will further reduce the transient flora, but only if it is used for several minutes.

Do you know that the most cases of NI happened in the ICU? And do you know why?

According to Dr. Hera, ICU is the place where most medical equipment used to support very sick people. This is where the use of antibiotics is the highest, about 10 times more than usual. Therefore, its uses normally wasn’t controlled, thus will cause problems when we face with chronic infection. Other than that, the irrational used of antibiotics can cause the increase NI cases and bacteria resistance.

How to identify NI cases in the hospital?

For this, there’s a special committee to monitor NI cases in the hospital. The infection control nurse will observe for any NI cases. They will record the data in the surveillance report and report it to the head of the ward. Then the head of the ward will report it to the NI committee. The NI committee will then visit the patient to see if it’s really NI or not, then they will discuss the case and report it to the hospital director. 

REFERENCES:

1. Dr. Hera Nirwati: Nosocomial Infection
2. Prof. Victor Lim; International Medical University: Health Care Associated Infections and its Control