Hospital-Acquired Infection (Nosocomial Infection) Hazem Al-Khafaji Department of internal medicine college of medicine Al-Qadissyia university Lecture 4

Definition Nosocomial infections are infections acquired in hospitals and other healthcare facilities. The infection to be classified as nosocomial infection should be: 1- The patient must have been admitted for reasons other than the infection. 2- The patient must also have shown no signs of active or incubating infection.

The nosocomial infections occur: up to 48 hours after hospital admissionup to 3 days after discharge from the hospital up to 30 days after an operation in a healthcare facility when a patient was admitted for reasons other than the infection

Epidemiology In the United States, it has been estimated that 9.2 out of every 100 patients acquire a nosocomial infection.  In UK about 6-10%.  100,000 infections per year in UK  5,000 deaths with nosocomial infections playing a role in 15,000 others.

Frequency of infection(WHO Report) Nosocomial infections occur worldwide and affect both developed and resource-poor countries. Infections acquired in health care settings are among the major causes of death and increased morbidity among hospitalized patients. They are a significant burden both for the patient and for public health.An average of 8.7% of hospital patients had nosocomial infections. At any time, over 1.4 million people worldwide suffer from infectious complications acquired in hospital. The highest frequencies of nosocomial infections were reported from hospitals in the Eastern Mediterranean and South-East Asia Regions (11.8 and 10.0% respectively).

What are the factors influence the development of infection in hospital? Consider 4 important factors… The host The microbes The environment Treatment

The Cycle of Contagion Susceptible person Infection or colonisation Transmission Pathogen

Factors influencing the development of nosocomial infections: The microbial agent: Factors leading to infection depends partly on the: 1- characteristics of the microorganisms. 2- including resistance to antimicrobial agents. 3- intrinsic virulence. 4- amount of infective material (inoculum). 5-nosocomial infections are often caused by opportunistic pathogens. 6- antibiotic resistance is a problem.

Environmental factors : 1- Health care settings are an environment where both infected persons and persons at increased risk of infection contact each other. 2- Patients with infections or carriers of pathogenic microorganisms admitted to hospital are potential sources of infection for patients and staff. 3- Patients who become infected in the hospital are a further source of infection. 4- Crowded conditions within the hospital. 5-Frequent transfers of patients from one unit to another, and concentration of patients highly susceptible to infection in one area.

Host(Patient) susceptibility: Important patient factors influencing acquisition of infection include 1- Age(the extremes of life — infancy and old age — are associated with a decreased resistance to infection). 2-Immune status. 3- Underlying disease. 4- Diagnostic and therapeutic interventions. 5-Patients with chronic disease such as malignant tumors, leukemia, diabetes mellitus, renal failure, or (AIDS) have an increased susceptibility to infections with opportunistic micro-organisms.

Treatment: The widespread use of antimicrobials for therapy or prophylaxis (including topical) is the major cause of development of resistance. Antimicrobial agents are, in some cases, becoming less effective because of resistance. As an antimicrobial agent becomes widely used, bacteria resistant to this drug eventually emerge and may spread in the health care setting. Many strains of pneumococci, staphylococci(Methicillin Resistant Staphylococcus aureus (MRSA), enterococci, and tuberculosis are currently resistant to most or all antimicrobials which were once effective. Multiresistant Klebsiella and Pseudomonas are prevalent in many hospitals.

Commonest nosocomial infections( Type of nosocomial infection) 1- Urinary tract infection( Positive urine culture (1 or 2 species) with at least bacteria/ml), with or without clinical symptoms. 2- Surgical site infection Any purulent discharge, abscess, or spreading cellulitis at the surgical site during the month after the operation. 3- Respiratory infection:symptoms with at least two of the following signs appearing during hospitalization: — cough — purulent sputum — new infiltrate on chest radiograph consistent with infection. 4-Vascular catheter Inflammation, lymphangitis or infection purulent discharge at the insertion site of the catheter. 5-Septicaemia Fever or rigors and at least one positive blood culture

6-Other nosocomial infections: There are many other potential sites of infection. For example: ● Skin and soft tissue infections: open sores (ulcers, burns and bedsores) encourage bacterial colonization and may lead to systemic infection. ● Gastroenteritis is the most common nosocomial infection in children, where rotavirus is a chief pathogen: Clostridium difficile is the major cause of nosocomial gastroenteritis in adults in developed countries. ● Sinusitis and other enteric infections, infections of the eye and conjunctiva. ● Endometritis and other infections of the reproductive organs following childbirth.

Pathogens(Microorganisms ) cause nosocomial infections:. The infecting organisms vary among different patient populations, different health care settings, different facilities, and different countries. 1- Bacteria: These are the most common nosocomial pathogens. A-Commensal bacteria may cause infection if the natural host is compromised. For example, cutaneous coagulasenegative staphylococci cause intravascular line infection and intestinal Escherichia coli are the most common cause of urinary infection. B-Pathogenic bacteria have greater virulence, and cause infections (sporadic or epidemic) regardless of host status. For example: — Anaerobic Gram-positive rods (e.g. Clostridium) cause gangrene. — Gram-positive bacteria: Staphylococcus aureus (cutaneous bacteria that colonize the skin and nose of both hospital staff and patients) cause a wide variety of lung, bone, heart and bloodstream infections.

— Gram-negative bacteria: Enterobacteriacae (e.g. Escherichia coli, Proteus, Klebsiella, Enterobacter, may colonize sites when the host defences are compromised (catheter insertion, bladder catheter, cannula insertion) and cause serious infections (surgical site, lung, bacteraemia, peritoneum infection). They may also be highly resistant. Gram-negative organisms such as Pseudomonas spp. are often isolated in water and damp areas. They may colonize the digestive tract of hospitalized patients. — Selected other bacteria are a unique risk in hospitals. For instance, Legionella species may cause pneumonia (sporadic or endemic) through inhalation of aerosols containing contaminated water (air conditioning, showers, therapeutic aerosols).

2 – Viruses There is the possibility of nosocomial transmission of many viruses, including the hepatitis B and C viruses (dentists,transfusions, dialysis, injections, endoscopy), respiratory syncytial virus (RSV). 3- Parasites and fungi Some parasites (e.g. Giardia lamblia) are transmitted easily among adults or children. Many fungi and other parasites are opportunistic organisms and cause infections during extended antibiotic treatment and severe immunosuppression (Candida albicans, Aspergillus spp., Cryptococcus neoformans, Cryptosporidium). These are a major cause of systemic infections among immunocompromised patients. Environmental contamination by airborne organisms such as Aspergillus spp. which originate in dust and soil is also a concern, especially during hospital construction. Sarcoptes scabies (scabies).

Reservoirs(source of infection): Bacteria that cause nosocomial infections can be acquired in several ways: 1.The permanent or transient flora of the patient (endogenous infection). Bacteria present in the normal flora cause infection because of transmission to sites outside the natural habitat (urinary tract), damage to tissue (wound) or inappropriate antibiotic therapy that allows overgrowth. 2. Flora from another patient or member of staff (exogenous cross-infection ).

Modes of transmission of nosocomial pathogens: 1- Direct contact: Hands of health care workers is the most important source of infection.Transmission prevented signifecntly by handwashing. 2- Airborne agent: Agent present in water, waterborne agent as Legionella pneumophila epidemic. 3- Droplets transmission as pulmonary tuberculosis & viruses. 4- Vehicle transmission as contaminated blood,plasma & fluids. as hepatitis C & B. 5- Food borne as E.histolytica. 6-vector transmission as malaria in Africa.

The 5 pillars of infection control Isolation & barrier precautions Decontamination of equipment Prudent use of antibiotics Hand washing Decontamination of environment

Next lecture Parasitic infection Thank you