Etiology of microorganisms

In hospital, patients may be exposed to, potential pathogens outside of the healthcare setting before receiving treatment, or may develop infections caused by those pathogens when exposed to the conditions associated with delivery of every healthcare action. Infections of the lungs, wounds, urinary tract and bloodstream can be contracted in hospital. These are called hospital-acquired infections (HAI).

Any medical procedure that results in contact with body fluids and secretions has associated risks and endoscopic (colonoscopy, EGD, ERCP) procedures are no exception.

Nosocomial (Hospital-Acquired) Infections

A nosocomial infection is any infection that is acquired during the course of stay in a hospital, nursing home, or other health care facility.About 5-15% or all hospitalized patients acquire nosocomial infections.

Three factors contribute to nosocomial infections:

•Microorganisms in the hospital

•A compromised host

•The chain of transmission

Nosocomial infections are widespread. They are important contributors to morbidity and mortality. They will become even more important as a public health problem with increasing economic and human impact because of:• Increasing numbers and crowding of people.• More frequent impaired immunity (age, illness, treatments).• New microorganisms.• Increasing bacterial resistance to antibiotics.

These standards recognize the risks that can be present from contact or transmission of enteric secretions, which can most notably include C.diff, VRE, MRSA, and E. coli, in addition to blood borne pathogens, GI borne viruses, and other pathogens that, when present, are often colonized or have reservoirs in the GI tract.

HAI Pathogens

The 10 most common infection-causing pathogens, accounting for 84% of HAIs, are

–negative staphylococci (15%), –Staphylococcus aureus (15%), –Enterococcus species (12%), –Candida species (11%), –Escherichia coli (10%), –Pseudomonas aeruginosa (8%), –Klebsiella pneumoniae (6%), –Enterobacter species (5%), –Acinetobacter baumannii (3%) and –Klebsiella oxytoca (2%).

Factors influencing the development ofnosocomial infections

The microbial agent

Infections may be caused by a microorganism acquired from anotherperson in the hospital (cross-infection) or may be caused by the patient’s own flora (endogenous infection).

The Compromised Host Patients with burns, surgical wounds, and suppressed immune systems are the most susceptible to nosocomial infections.

The Chain Of Transmission

Nosocomial infections are transmitted by direct contact between staff members and patients and between patients. Fomites such as catheters, syringes, and respiratory devices can transmit nosocomial infections.

Type of HAI Simplified criteria infection

•Surgical site infectionAny purulent discharge, abscess, or spreading cellulitis at the surgical site during the month after the operation

•Urinary infectionPositive urine culture (1 or 2 species) with at least 105 bacteria/ml, with or without clinical symptoms

•Respiratory infection

Respiratory symptoms with at least two of the following signsappearing during hospitalization:— cough— purulent sputum— new infiltrate on chest radiograph consistent with infection

•Vascular catheter infectionInflammation, lymphangitis or purulent discharge at the insertion site of the catheter

•SepticaemiaFever or rigours and at least onepositive blood culture

Clostridium difficile (C. difficile/C. diff)

• is a spore forming, gram-positive bacillus that produces exotoxins that are pathogenic to humans. C. difficile-associated disease (CDAD) can range in severity from mild diarrhea to fulminant colitis and death. Risk factors attributed to acquiring C. difficile associated disease (CDAD or infection include gastrointestinal procedures and surgery, advanced age, and prior exposure to antibiotics and proton pump inhibitors (PPI's).

VRE (Vancomycin Resistant Enterococcus)

• Enterococci are bacteria that are commonly found in the GI tract of 95% of the population. As these are generally normal flora, these bacteria rarely cause illness in healthy people. Vancomycin in an antibiotic used to treat very serious infections. It is often used to treat enterococci as they are resistant to many other types of antibiotics. VRE is associated with increased mortality, length of hospital stay, admission to the ICU, surgical procedures and costs.

MRSA (methicillin-resistant Staphylococcus aureus)

• is a type of staph bacteria that is resistant to treatment with commonly prescribed antibiotics such as methicillin, penicillin and amoxicillin. People infected with MRSA are more likely to have longer, more expensive hospital stays or die as a result of the infection.

Staphylococcus aureus, also known as “staph,” are bacteria commonly carried on the skin or in the nose of healthy people. Sometimes staph bacteria can cause serious infections.

• MRSA is usually spread from person to person through direct skin contact or contact with shared items or surfaces that have touched a person’s infection (e.g., towel, equipment surface). This makes some settings more conducive to the transmission of MRSA, such as hospitals, recreational facilities, locker rooms, sports venues, schools and daycare centers.

Risk factors

• At risk populations include:• People with weak immune systems (people living with HIV/AIDS,

cancer patients, transplant recipients, severe asthmatics, etc.) • Diabetics • Intravenous drug users • Use of quinolone antibiotics• Young children • The elderly • College students living in dormitories • People staying or working in a health care facility for an extended

period of time • People who spend time in coastal waters where MRSA is present,

such as some beaches in Florida and the west coast of the United States

• People who spend time in confined spaces with other people, including prison inmates, military recruits in basic training, and individuals who spend considerable time in changerooms or gyms.

How prevent the spread of MRSA?

The CDC (Centers for Disease Control and Prevention) recommends practicing good personal hygiene such as frequent washing of hands with soap and water or an alcohol-based hand rub. Other recommendations include:

• Proactive hospital screening of targeted high-risk populations, which allows for early identification, isolation and treatment of infected individuals.

• Cover cuts and abrasions with clean, dry bandages until healed.

• Avoid sharing personal items such as towels, razors and ointments.

• Cleaning procedures should focus on commonly touched surfaces.

• Use Environmental Protection Agency (EPA) registered disinfectants.

E. coli (Escherichia coli)

E. coli is also a frequent cause of other bacterial infections including cholecystitis, bacteremia, cholangitis, travelers diarrhea, prostatitis, and pneumonia.

is a type of bacteria commonly found in the digestive tract, primarily inhabiting the large intestine. E. coli is spread through contact with fecal contamination, and causes 3 primary types of infection, including urinary tract infections (UTI's), intestinal disease (e.g. gastroenteritis), and neonatal meningitis. E. coli is a leading cause of both community-acquired and nosocomial urinary tract infections, accounting for 90% of all UTI's and up to 50% of nosocomial infections.

High risk areas in the hospital

These areas in the hospital carry a greater risk:• Nurseries• Intensive care unit• Dialysis unit• Organ transplant unit• Burns unit• Operation theatres• Delivery rooms• Post-operative wards

Intensive Care Units (ICU)

• ICU patients may be infected with contagious pathogens, are often immunocompromised and at very high risk for spreading or developing HAIs. Disinfect with bleach to kill pathogens commonly found in ICUs, such as Staphylococcus aureus, Vancomycin Resistant Enterococcus faecalis (VRE) and Pseudomonas aeruginosa, to minimize cross-contamination.

Emergency Room (ER)

• With many patients coming through the door, ER surfaces require proactive disinfecting to prevent the spread of pathogens to the rest of the facility.

Operating Room

• With frequent surgery turnover and the presence of blood, tissue and other body fluids, ensuring a clean and disinfected operating room is of utmost importance.

Dialysis• Cross-contamination can pose a

significant risk to patients in dialysis centers. Bacterial infections are the second leading cause of death among dialysis patients. The most prevalent infections include Staphylococcus aureus (MRSA), Hepatitis B, Hepatitis C and HIV, which many dialysis disinfectants are not EPA-registered to kill. Proper surface disinfection - with an EPA-registered bleach disinfectant - and compliance with hand hygiene protocols are key to preventing infections in dialysis settings.

Endoscopy/GI Suite

• The tests conducted here can create a high risk for organism shedding, such as Clostridium difficile, and contamination of surfaces and medical equipment. Thorough disinfection of these areas is critical to breaking the cycle of indirect pathogen transmission.

Isolation Rooms

• Isolating patients with potentially deadly infections is not enough because HAI-causing pathogens can be transmitted through

contaminated surfaces.

Patient Room and Bathroom

With multiple patient, staff and visitor interactions occurring, these patient areas are prone to cross-contamination since so many different hands touch potentially contaminated surfaces every day. Some infectious germs can survive on these patient room surfaces for hours, days, even months. According to the Healthcare Infection Control Practices Advisory Committee (HICPAC) and CDC guidelines, high-touch surfaces should be more frequently cleaned and disinfected.

Microbes can spread and pass diseases in a number of ways:

• 1) By direct contact: physical contact (touching etc) with an infected person; sexually-transmitted diseases are passed on this way.

• 2) By indirect contact: touching something which an infected person has touched eg a towel, door knob, cup etc.

• 3) By inhalation: breathing in droplets containing microbes which have been produced by sneezing or coughing eg flu, TB, pneumonia.

• 4) By contaminated food or drink: eating food or drinking water which has been infected by microbes eg typhoid, cholera.

• 5) By animal vectors: animals can pass microbes on to humans by biting them eg fleas, mosquitoes.

Contact Transmission

a) direct contact

b) prevention of contact transmission

c) indirect contact

d) droplet

The Transmission Of Disease

Vehicle Transmission

a) water b) food c) air

Vectors of Disease