Nosocomial Infections (hospital-acquired infections)

Table of Contents

• Epidemiology of Nosocomial Infections 
• Types of Nosocomial Infections
• Central line associated bloodstream infections (CLABSIs)
• Catheter associated urinary tract infections (CAUTI)
• Surgical site infections (SSIs)
• Ventilator associated pneumonia (VAP)
• Nosocomial Pathogens
• Bacteria causing Nosocomial Infections
• Viruses causing Nosocomial Infections
• Fungal parasites causing Nosocomial Infections
• Routes of transmission of Nosocomial Infections
• Determinants
• Reservoirs and transmission of Nosocomial Infections
• Preventions of Nosocomial Infections
• Control of Nosocomial Infections
• Conclusion

Nosocomial infections are any infections that cause disease when the subject enters the hospital or gets treatment in an outpatient clinic (the term comes from the Latin nosocomium, meaning hospital).

• This type of illness is also known as a hospital-acquired infection (or, more generically, healthcare-associated infections).
• Nosocomial illnesses are those that appear 48 hours or more after being admitted to the hospital or 30 days after being released.
• Patients of all ages, clinical specialisations, and anatomical sites are susceptible to nosocomial infections. There is a chance that these infections will result in sepsis or even mortality.
• Longer hospital stays, permanent disabilities, higher rates of antimicrobial resistance, social turmoil, and higher mortality rates are all associated with increased infections.

Epidemiology of Nosocomial Infections 

• Infections in hospitals are frequent. According to a point prevalence survey carried out in 2011–12 among 231,459 patients in 947 acute care hospitals situated in 30 distinct European countries, 5.7% of patients had at least one nosocomial infection at any given moment.
• According to a WHO estimate, these infections affect 15% of all hospitalised patients.
• The incidence rates are greatest in South-East Asia and Sub-Saharan Africa at 75%, accounting for 4%–56% of all neonatal deaths.
• In middle- and low-income nations, the incidence varies from 5.7% to 19.1%, whereas it is adequately high in high-income nations (between 3.5% and 12%).
• The total frequency of infections is three times higher in low-income countries than in high-income countries, despite the fact that this incidence is 3–20 times higher in newborns.

Types of Nosocomial Infections

Nosocomial infections can be caused by a variety of factors. They are based on the kind of illness, where it came from, what pathogen caused it, and whether it is bacterial, fungal, or viral. Infections at surgical sites, urinary tract infections brought on by catheters, and pneumonia caused by a ventilator are the most frequent kinds of infections.

Central line associated bloodstream infections (CLABSIs)

• CLABSIs are fatal nosocomial infections with a mortality incidence ranging from 12% to 25%.
• A central line, also referred to as a central venous catheter, is a tube or catheter used to administer fluids, medications, or blood samples for specific medical procedures.
• Doctors typically administer it by injecting it into a sizable vein in the thorax, groyne, or neck.
• Central lines are most commonly used by doctors in intensive care units (ICUs).
• They have access to a sizable vein near to the heart and can remain in place for weeks or months. They therefore carry a higher chance of severe infection than other intravenous catheters, such as IVs.
• A CLABSI, a severe infection, may happen if viruses or bacteria infiltrate the bloodstream through the catheter.

Catheter associated urinary tract infections (CAUTI)

• The most prevalent kind of nosocomial infection globally is CAUTI.
• As of 2011, more than 12% of infections in acute care hospitals were found to be UTIs.
• CAUTIs are brought on by the patient's own endogenous local microflora.
• When catheters are inserted, they serve as a pathway for the entry of bacteria; additionally, when the catheter's insufficient drainage leaves some urine in the bladder, the environment is more favourable for bacterial development.
• While female patients may develop pyelonephritis, cystitis, and encephalopathy from CAUTI, male patients may experience orchitis, epididymitis, and prostatitis.

Surgical site infections (SSIs)

• 2-5% of surgical patients develop nosocomial illnesses called SSIs.
• These infections, which are the second most common kind of nosocomial infections, are mainly caused by Staphylococcus aureus and require extended hospitalisation because they increase the risk of death.
• The patient's own endogenous microflora produces the pathogens that induce SSI.
• The incidence could reach 20%, depending on the method and monitoring standards applied.

Ventilator associated pneumonia (VAP)

• 9 to 27% of people who are on a ventilator with mechanical assistance develop nosocomial pneumonia, also known as VAP.
• It typically occurs 48 hours following tracheal colonisation.
• Ventilation is the root cause of 86% of nosocomial pneumonia.
• Leucopenia, fever, and bronchial noises are some of the signs of VAP.

Nosocomial Pathogens

Nosocomial illnesses are brought on by bacteria, viruses, and fungus parasites. Different patient populations, healthcare settings, and even variations in the environment where treatment is given affect how these microorganisms behave.

Bacteria causing Nosocomial Infections

• Bacteria are the most common pathogens to induce nosocomial infections.
• Some are naturally occurring in the patient and only cause illness when the patient's immune system is weakened.
• Infections in critical care units are brought on by the pathogenic bacterial species collectively known as Acinetobacter.
• It is found in both soil and water and accounts for 80% of documented infections.
• The colon and gastrointestinal system contain Bacteroides fragilis, a commensal bacterium. When other bacteria are prevalent, infections are triggered.
• Clostridium difficile causes intestinal inflammation that leads to colitis and diarrhoea brought on by antibiotic use because it displaces healthy bacteria with pathogenic ones.

Viruses causing Nosocomial Infections

• Viruses, in addition to bacteria, are a major factor in nosocomial illnesses.
• Routine tracking indicates that 5% of all nosocomial infections are caused by viruses.
• They can spread through nasal, oral-fecal, and hand-to-mouth contact.
• The persistent virus-based disease is referred to as hepatitis.
• Hepatitis viruses can be passed from staff members to patients while receiving medical treatment.
• Hepatitis B and C are commonly transmitted through unsafe injection techniques.
• Rotavirus, herpes simplex, HIV, influenza, and other viruses are examples of other viruses.

Fungal parasites causing Nosocomial Infections

• In people with weakened immune systems, fungus parasites function as opportunistic pathogens and cause nosocomial infections.
• Aspergillus spp. environmental pollution can cause infections.
• Additionally, Cryptococcus neoformans and Candida albicans can cause infections during medical stays.
• While Candida infections are caused by the patient's own internal flora, Aspergillus infections are caused by inhaling fungus spores from contaminated air during hospital building or renovation.

Routes of transmission of Nosocomial Infections

Pathogens are spread primarily through five different channels;

1. Contact transmission ( direct or indirect)

• It is both the most important and frequent method of transmitting nosocomial infections.
• Microorganisms can be spread by contaminated tools, needles, or dressings as well as from one bodily surface to another.

2. Droplet transmission

• Sneezing, coughing, or operations on the respiratory system like bronchoscopy or suction all result in the production of droplets.

3. Vector transmission

• Insects and other invertebrates propagate diseases (for example, mosquitoes transmit malaria and yellow fever, and fleas transmit plague).

4. Airborne transmission

• Small (5 micron) droplet nuclei or dust particles floating in the atmosphere.

5. Common vehicle transmission

• spread by indirect contact with contaminated substance (e.g., contaminated food, blood products, water, contaminated instruments, and other items).

Determinants

Risk factors for nosocomial infections include the setting in which care is given, the patient's vulnerability, and staff and medical professionals' ignorance of such pervasive infections.

1. Environment 

• medical facilities that are not properly kept and inadequate waste removal.

2. Susceptibility

• antibiotic use over a protracted period of time, patient immune suppression, and prolonged ICU stay

3. Unawareness

• incorrect injection methods, a lack of control policies, a lack of knowledge of the basics of infection control, and improper use of invasive devices (like catheters).
• In low-income nations, these risk factors are associated with poverty, a lack of financial assistance, understaffed medical facilities, and an insufficient quantity of equipment.

Reservoirs and transmission of Nosocomial Infections

1. Microflora of patient

• Bacteria from the patient's endogenous flora may spread to tissue wounds or surgical areas and cause infection.
• Following abdominal surgery, SSI is brought on by gram-negative bacteria in the digestive system.

2. Patient and staff

• Through direct contact with patients (hands, saliva, other bodily fluids, etc.) and staff members (water, food, other bodily fluids, during direct contact, or through other environmental sources), pathogen transmission happens during treatment.

3. Environment

• Pathogens that can spread illness can be found in food, water, and medical equipment.
• Transmission to another patient creates a new reservoir for healthy individuals.

Preventions of Nosocomial Infections

Nosocomial infections are a major cause of illness and death, so it is important to prevent them from the start in order to halt their spread.

1. Transmission from environment 

• Unhygienic conditions are the ideal ones for the infectious organism to flourish in.
• Food, water, and airborne contaminants can all disseminate to patients undergoing medical treatment.
• The cleaning and treatment of beds, baths, toilets, walls, floors, windows, and other medical apparatus must be governed by policies.
• With adequate ventilation and clean, filtered air, airborne bacterial contamination can be completely eradicated.
• The ventilation and filter systems in general wards, operating rooms, and critical care units require routine upkeep and documentation.
• Microbiological monitoring methods should be applied to water analysis.
• Patients who are infected need to take separate showers.
• Food preparation errors can lead to foodborne infections.

2. Transmission from staff

• There is a chance that medical personnel will disseminate an infection.
• It is the duty of healthcare workers to take part in infection control.
• Staff members should practise excellent personal hygiene because it is necessary.
• You must correctly decontaminate your hands with hand disinfectants after coming into contact with infected patients.
• It is important to use sterile equipment and safe injection methods.
• Masks, gloves, head coverings, and suitable uniforms are essential for the delivery of healthcare.

3. Hospital waste management

• Hospital waste could serve as a pathogen reservoir, so it needs to be managed carefully.
• 10 to 25 % of the waste generated by healthcare institutions is classified as hazardous waste.
• Infectious waste from hospitals should be stored in an area that is only accessible by limited personnel.
• All waste types must be disposed of separately, including metal waste, surgical waste, waste from infected individuals, waste contaminated with blood and sputum, and waste from diagnostic laboratories.

Control of Nosocomial Infections

Nosocomial diseases have been significantly reduced through prevention, but more needs to be done to keep them under control. Every day, there is a possibility that one out of every 25 hospital patients will acquire at least one kind of nosocomial infection.

1. Infection control programs

• Healthcare facilities should create prevention plans for these diseases, including immunisation drives, regular precautions, and transmission-based safeguards.
• Administration, staff, and patients admitted to or visiting hospitals must take these programmes into account in order to perform their duties in infection prevention.

2. Appropriate antimicrobial use

• Antibiotics are frequently used to cure illnesses.
• A accurate clinical diagnosis of the infection-causing microorganism is required before taking antibiotics.
• About 50 million of the approximately 100 million courses of antibiotics that are given by physicians in offices each year are unnecessary, according to the Centers for Disease Control and Prevention (CDC).
• The choice of antibiotics should take the patient's tolerance into consideration in addition to the type of disease and pathogen.

Conclusion

Due to increasing nosocomial infection rates and antimicrobial resistance, it is now more difficult for infection control committees and healthcare administrations to achieve the goal of eliminating intervals.

However, by adopting sound and healthy care delivery strategies developed by infection control committees and preventing the spread of these infections using the proper antibiotic use strategies, it is possible to significantly reduce the resistance of emerging pathogens to antibiotics.