Bacteria are considered multi-resistant to antibiotics when they develop a resistance to several families of antibiotics, and can only be treated by a limited number of antibiotics. Any bacteria resistant to three or more antibiotics is considered multi-resistant. Multi-resistance is insidious because it renders certain infections untreatable. In other words, they become medical dead-ends. MRB's include communal infections such as pneumococcus, T.B. bacillus, as well as nosocomial infections. (France: RAISIN report, January 2006).
The appearance of new antibiotics is quickly accompanied by resistant bacteria. The emergence of MRB's is therefore closely linked to antibiotic use in health care institutions and family medicine. Non compliance with basic cleanliness measures facilitates the spread of MRB's by person to person contact as well as by contact with a contaminated environment. All bacteria, whether resistant or not, are easily transmitted by hands.
What is bacterial resistance?
Bacterial resistance is the ability to resist the very antibiotics and germicides intended to control them. The evolution towards antibiotic resistance became a serious problem towards the end of the twentieth century. The term multi-resistant refers to any bacterial strain resistant to several germicides or antibiotics. For example, multi-resistant tuberculosis is resistant to several antibiotics that have a completely different chemical structure.
Cross-resistant bacteria are able to resistt antibiotics that have a different molecular structure but use the same mechanism to fight infection.
Bacteria can transfer genetic material to other bacteria resulting in co-resistance. This occurs when the genetic code for several unrelated resistance mechanisms is transferred to a new host bacteria.
Research in bacterial resistance has led to important discoveries concerning the genetic structure of these bacteria and measures to eradicate them. Such information is invaluable to doctors because it allows them to use antibiotics more effectively.
Antibiotics: how they work against bacteria
To be effective against pathogenic bacteria, antibiotics must:
- recognize the target
reach the target
be prescribed in sufficient doses for as long as required.
Resistance Mechanisms
Resistance can be transmitted from one generation to another (mother - daughter) or from one bacterial strain to another (lateral transmission).
Multi-resistant bacteria
Certain bacteria have become resistant to several antibiotics. The following list identifies several MRB's:
- MRSA - Methicillin-resistant Staphylococcus aureus
- Enterococcus ESLB (extended spectrum beta-lactamases)
- enterococcus aerogene strains producing derepressed cephalosporinase
- ceftazidim resistant P. aeruginosa
- glycopeptide resistant enterococcus
- imipenem resistant A. baumanii
- environmental bacteria such as S. maltophilia and B. cepacia
Why fight agains MRB's?
MRB infections require longer, more onerous, and complex antibiotic treatment. Infected patients tend to be hospitalized longer and at greater cost to the health care system. MRB carriers are not necessarily infected with a nosocomial infection and, inversely, NI's are not always MRB's. Hospital workers and patients along with the general public can be carriers for a period of months or longer.
Hospitals are a source or MRB's
There are several contributing factors:
- antibiotic pressure
- mutant resistant bacteria
- extended spectrum antibiotic treatment (with a single antibiotic)
- insufficient doses
- length of antibiotic treatment
- transmission of resistant clones
Other factors:
- length of hospital stay
- severity of the illness
- invasive procedures
Key factors in reducing MRB transmission
- Labs must detect MRB's.
- identify patients who are carriers.
- daily computerized alerts.
- predict the appearance of MRB's.
- effective use of antibiotics.
- participation in surveillance networks.
Standard precautions must be respected by all personnel for each and every patient
- implementation of additional cleanliness measures adapted to a specific situation.
- broad use of alcohol based sanitizers.
- accurate information on patients and their entourage.
- MRB's must be included in patient's files. All treating personnel must be advised of an infected patient's condition. This information must be passed on when patients are transferred to another hospital.
- prevention of MRB's depends on their type and location (in a patient's urine, stool, wounds, bronchi etc).
- increase cleanliness surveillance of the hospital environment, patient's rooms, and equipment with which patients come into contact; examination tables, medical devices that touch a patient's skin such as stethoscopes, otoscopes, blood pressure cuffs etc.
- proper daily maintenance of the entire hospital: patient's rooms, examination rooms, offices, waiting rooms, reception areas, hallways, storage areas for janitorial equipment etc. Maintenance should be carried out starting with the cleanest surfaces and moving on to the dirtiest surfaces, and from top to bottom. The highest risk zones are sinks, toilets, showers, patients rooms, and examination rooms.
- proper disposal of garbage is critical. Strict rules must be implemented for wrapping, storing, and disposing of regular hospital waste as well as high risk contaminated waste related to treatment
- These rules must be rigorously applied
Patients
It is important to remind patients about basic cleanliness measures, specifically washing one's hands in the following situations:
- after touching a portable urinal, dirty bedding or bandages.
- after coughing, sneezing, or blowing one's nose.
- after using the bathroom.
Hospital units must be washed and disinfected with bleach. It is also necessary to follow proper procedure when cleaning and disinfecting janitorial equipment. For example, washing machine temperature must be set at 40 degrees Celsius.
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