BY MUHAMMAD BELLO MUSTAPHA
A nosocomial infection: also called “hospital acquired infection” can be defined as an infection acquired in hospital by a patient who was admitted for a reason other than that infection. An infection occurring in a patient in a hospital or other health care facility in whom the infection was not present or incubating at the time of admission. This includes infections acquired in the hospital but appearing after discharge, and also occupational infections among staff of the facility. Patient care is provided in facilities which range from highly equipped clinics and technologically advanced university hospitals to front-line units with only basic facilities. Despite progress in public health and hospital care, infections continue to develop in hospitalized patients, and may also affect hospital staff. Many factors promote infection among hospitalized patients: decreased immunity among patients; the increasing variety of medical procedures and invasive techniques creating potential routes of infection; and the transmission of drug-resistant bacteria among crowded hospital populations, where poor infection control practices may facilitate transmission.
Hospital-acquired infections add to functional disability and emotional stress of the patient and may, in some cases, lead to disabling conditions that reduce the quality of life. Nosocomial infections are also one of the leading causes of death. The economic costs are considerable.
The increased length of stay for infected patients is the greatest contributor to cost. One study showed that the overall increase in the duration of hospitalization for patients with surgical wound infections was 8.2 days, ranging from 3 days for gynecology to 9.9 for general surgery and 19.8 for orthopedic surgery. Prolonged stay not only increases direct costs to patients or payers but also indirect costs due to lost work.
The increased use of drugs, the need for isolation, and the use of additional laboratory and other diagnostic studies also contribute to costs. The advancing age of patients admitted to health care settings, the greater prevalence of chronic diseases among admitted patients.
This study is aimed at studying:
The main causes of nosocomial infections
Factors that influence nosocomial infections
Criteria for its surveillance
Universal prevention, control and management of nosocomial infection
FACTORS INFLUENCING NOSOCOMIAL INFECTIONS
THE MICROBIAL AGENT
The patient is exposed to a variety of microorganisms during hospitalization. Contact between the patient and a microorganism does not by itself necessarily result in the development of clinical disease, other factors influences the nature and frequency of nosocomial infections. The likelihood of exposure leading to infection depends partly on the characteristics of the microorganisms, including resistance to antimicrobial agents, intrinsic virulence, and amount (inoculum) of infective material. Many different bacteria, viruses, fungi and parasites may cause nosocomial infections. Infections may be caused by a microorganism acquired from another person in the hospital (cross-infection) or may be caused by the patient’s own flora (endogenous infection). Some organisms may be acquired from an inanimate object or substances recently contaminated from another human source (environmental infection).
Important patient factors influencing acquisition of infection include age, immune status, underlying disease, and diagnostic and therapeutic interventions. The extremes of life (infancy and old age) are associated with a decreased resistance to infection. Patients with chronic disease such as malignant tumors, leukemia, diabetes mellitus, renal failure, or the acquired immunodeficiency syndrome (AIDS) have an increased susceptibility to infections with opportunistic pathogens. The latter are infections with organisms that are normally innocuous, e.g. part of the normal bacterial flora in the human, but may become pathogenic when the body’s immunological defenses are compromised. Immunosuppressive drugs or irradiation may lower resistance to infection. Injuries to skin or mucous membranes bypass natural defense mechanisms. Malnutrition is also a risk. Many modern diagnostic and therapeutic procedures, such as biopsies, endoscopic examinations, catheterization, intubation/ventilation and suction and surgical procedures increase the risk of infection. Contaminated objects or substances may be introduced directly into tissues or normally sterile sites such as the urinary tract and the lower respiratory tract.
iii. ENVIRONMENTAL FACTORS
Health care settings are an environment where both infected persons and persons at increased risk of infection congregate. Patients with infections or carriers of pathogenic microorganisms admitted to hospital are potential sources of infection for patients and staff. Patients who become infected in the hospital are a further source of infection. Crowded conditions within the hospital, frequent transfers of patients from one unit to another, and concentration of patients highly susceptible to infection in one area (e.g. Newborn infants, burn patients and intensive care) all contribute to the development of nosocomial infections. Microbial flora may contaminate objects, devices, and materials which subsequently contact susceptible body sites of patients.
iv. BACTERIAL RESISTANCE
Many patients receive antimicrobial drugs. Through selection and exchange of genetic resistance elements, antibiotics promote the emergence of multidrug resistant strains of bacteria, microorganisms in the normal human flora sensitive to the given drug are suppressed, while resistant strains persist and may become endemic in the hospital. The widespread use of antimicrobials for therapy or prophylaxis (including topical) is the major determinant 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, enterococci, and tuberculosis are currently resistant to most or all antimicrobials which were once effective. Multiresistant Klebsiella and Pseudomonas aeruginosa are prevalent in many hospitals. This problem is particularly critical in developing countries where more expensive second-line antibiotics may not be available or affordable.
SIMPLIFIED CRITERIA FOR SURVEILLANCE OF NOSOCOMIAL INFECTIONS
Type of nosocomial
Simplified criteria of Infection
Surgical site infection
Any purulent discharge, abscess, or spreading cellulites at the surgical site during the month after the operation
Positive urine culture (1 or 2 species) with at least 105 bacteria/ml, with or without symptom
Respiratory symptoms with at least two of the following signs appearing during hospitalization: cough, purulent sputum, new infiltrate on chest and radiographs consistent with infection
Inflammation, lymphangitis or infection purulent discharge at the insertion site of the catheter
CONTROL OF NOSOCOMIAL INFECTIONS
Prevention of nosocomial infections is the responsibility of all individuals and services providing health care. Everyone must work cooperatively to reduce the risk of infection for patients and staff. This includes personnel providing direct patient care, management and physical plant, provision of materials and products, and training of health workers. Infection control programmes are effective provided they are comprehensive and include surveillance and prevention activities, as well as staff training. There must also be effective support at the national and regional levels.
NATIONAL OR REGIONAL PROGRAMMES
The responsible health authority should develop a national (or regional) programme to support hospitals in reducing the risk of nosocomial infections. Such programmes must: set relevant national objectives consistent with other national health care objectives, develop and continually update guidelines for recommended health care surveillance, prevention and practice, develop a national system to monitor selected infections and assess the effectiveness of interventions, harmonize initial and continuing training programmes for health care professionals and facilitate access to materials and products essential for hygiene and safety.
ROLE OF HOSPITAL MANAGEMENT
The administration and/or medical management of the hospital must provide leadership by supporting the hospital infection programme. They should be responsible for: establishing a multidisciplinary Infection Control Committee, identifying appropriate resources for a programme to monitor infections and apply the most appropriate methods for preventing infection, ensuring education and training of all staff through support of programmes on the prevention of infection in disinfection and sterilization techniques and delegating technical aspects of hospital hygiene to appropriate staff, such as: nursing, housekeeping, maintenance and clinical microbiology laboratory management.
ROLE OF THE PHYSICIAN
Physicians have unique responsibilities for the prevention and control of hospital infections by: providing direct patient care using practices which minimize infections, following appropriate practice of hygiene (e.g. hand washing, isolation) serving on the Infection Control Committee and supporting the infection control team.
ROLE OF THE HOSPITAL PHARMACIST
The hospital pharmacist is responsible for: obtaining, storing and distributing pharmaceutical preparations using practices which limit potential transmission of infectious agents to patients, dispensing anti-infectious drugs and maintaining relevant records (potency, incompatibility, conditions of storage and deterioration), obtaining and storing vaccines or sera, and making them available as appropriate, maintaining records of antibiotics distributed to the medical departments, providing the Antimicrobial Use Committee and Infection Control Committee with summary reports and trends of antimicrobial use and having available the following information on disinfectants, antiseptics and other anti-infectious agents.
ROLE OF THE MICROBIOLOGIST
The microbiologist should handle patient and staff specimens with precaution to maximize the likelihood of a microbiological diagnosis, develop guidelines for appropriate collection, transport, and handling of specimens, ensuring laboratory practices meet appropriate standards, ensuring safe laboratory practice to prevent infections in staff, performing antimicrobial susceptibility testing following internationally recognized methods, and providing summary reports of prevalence of resistance, monitoring sterilization, disinfection and the environment where necessary and epidemiological typing of hospital microorganisms where necessary.
ROLE OF THE NURSING STAFF
Implementation of patient care practices for infection control is the role of the nursing staff. Nurses should be familiar with practices to prevent the occurrence and spread of infection, and maintain appropriate practices for all patients throughout the duration of their hospital stay. The nurse in charge of a ward is responsible for: maintaining hygiene, consistent with hospital policies and good nursing practice on the ward, monitoring aseptic techniques, including hand washing and use of isolation, reporting promptly to the attending physician any evidence of infection in patients under the nurse’s care, initiating patient isolation and ordering culture specimens from any patient showing signs of a communicable disease. When the physician is not immediately available, limiting patient exposure to infections from visitors, hospital staff, other patients, or equipment used for diagnosis or treatment, maintaining a safe and adequate supply of ward equipment, drugs and patient care supplies.
ROLE OF THE INFECTION CONTROL TEAM: HOSPITAL HYGIENE SERVICES
The infection control programme is responsible for oversight and coordination of all infection control activities to ensure an effective programme. The hospital hygiene service is responsible for: organizing an epidemiological surveillance programme for nosocomial infections, participating with pharmacy in developing a programme for supervising the use of anti-infective drugs, ensuring patient care practices are appropriate to the level of patient risk, checking the efficacy of the methods of disinfection and sterilization and the efficacy of systems developed to improve hospital cleanliness, participating in development and provision of teaching programmes for the medical, nursing, and allied health personnel, as well as all other categories of staff.
UNIVERSAL PRECAUTIONS OF NOSOCOMIAL INFECTIONS
All staff must maintain good personal hygiene. Nails must be clean and kept short. False nails should not be worn. Hair must be worn short or pinned up. Beard and moustaches must be kept trimmed short and clean.
Staff can normally wear a personal uniform or street clothes covered by a white coat. In special areas such as burn or intensive care units, uniform trousers and a short-sleeved gown are required for men and women. In other units, women may wear a short sleeved dress. The working outfit must be made of a material easy to wash and decontaminate. If possible, a clean outfit should be worn each day. An outfit must be changed after exposure to blood or if it becomes wet through excessive sweating or other fluid exposure. In aseptic units and in operating rooms, staff must wear dedicated shoes, which must be easy to clean. In aseptic units, operating rooms, or performing selected invasive procedures, staff must wear caps or hoods which completely cover the hair. Masks of cotton wool, gauze, or paper are ineffective. Paper masks with synthetic material for filtration are an effective barrier against microorganisms. Masks are used in various situations; mask requirements differ for different purposes. Staff wears masks to work in the operating room, to care for immune-compromised patients, to puncture body cavities. A surgical mask is sufficient. Staff must wear masks when caring for patients with airborne infections, or when performing bronchoscopes or similar examination. A high-efficiency mask is recommended. Patients with infections which may be transmitted by the airborne route must use surgical masks when outside their isolation room. Gloves are used for Patient protection staff wear sterile gloves for surgery, care for immune-compromised patients, invasive procedures which enter body cavities. Non-sterile gloves should be worn for all patient contacts where hands are likely to be contaminated, or for any mucous membrane contact. Staff wears non-sterile gloves to care for patients with communicable disease transmitted by contact, to perform bronchoscopies or similar examinations. Hands must be washed when gloves are removed or changed. Disposable gloves should not be reused. Latex or polyvinyl-chloride is the materials most frequently used for gloves. Quality, i.e. absence of porosity or holes and duration of use vary considerably from one glove type to another. Sensitivity to latex may occur, and the occupational health programme must have policies to evaluate and manage this problem.
CLEANING OF THE HOSPITAL ENVIRONMENT
Routine cleaning is necessary to ensure a hospital environment which is visibly clean, and free from dust and soil. Ninety per cent of microorganisms are present within “visible dirt”, and the purpose of routine cleaning is to eliminate this dirt. Neither soap nor detergents have antimicrobial activity, and the cleaning process depends essentially on mechanical action. There must be policies specifying the frequency of cleaning and cleaning agents used for walls, floors, windows, beds, curtains, screens, fixtures, furniture, baths and toilets, and all reused medical devices.
DISINFECTION OF PATIENT EQUIPMENT
Disinfection removes microorganisms without complete sterilization to prevent transmission of organisms between patients. Disinfection procedures must: meet criteria for killing of organisms, have a deterrent Effect, act independently of the number of bacteria present, the degree of hardness of the water, or the presence of soap and proteins (that inhibit some disinfectants). To be acceptable in the hospital environment, they must also be: easy to use, non-volatile, not harmful to equipment, staff or patients, free from unpleasant smells and effective within a relatively short time.
Hospital-acquired infections add to functional disability and emotional stress of the patient and may, in some cases, lead to disabling conditions that reduce the quality of life. Nosocomial infections are also one of the leading causes of death, and therefore a team work of high specialties in the health centers (physician, pharmacist, medical laboratory scientist and nurses) is highly recognized to implement safety measure and good relationships with patients so as to reduce the epidemiology of nosocomial infections.
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