Bacteria involved in various pathologies, staphylococci (golden, white, etc.) are often responsible for infections contracted in hospitals. Definition, symptoms, contagion and treatments with Dr. Tarek Msadek, head of the Department of Microbiology at the Institut Pasteur.
THE staphylococcus is a bacterial germ of the kind Staphylococcus, of which different strains exist. In humans, the most common are Staphylococcus aureus (or Staphylococcus aureus), THE Staphylococcus epidermidis (or white staphylococcus), but also the Staphylococcus saprophyticus. These can be present in all environments (water, soil, air, food, objects). “We can find staphylococci on our skin, on the mucous membranes, in the nose… without this causing any symptoms“, explains Dr. Tarek Msadek, Head of the Department of Microbiology at the Institut Pasteur. “But itstaphylococci can nevertheless become pathogenic (responsible for a pathology) when they find themselves in a place where they should not be, and they then generate various infections“The severity of these is defined by the type of bacteria and where it is found. The two most common staphylococci in men are staphylococci gold and white.”They are distinguished by their virulence factors: the first is the most serious of the staphylococci, while the second mainly attacks the epidermis.“says the specialist.
THE Staphylococcus aureus is, with the bacterium Escherichia coli, one of the germs most responsible fornosocomial infections (acquired in hospital)”30 to 50% of the population has Staphylococcus aureus on them asymptomatically, that is to say without there being any symptoms“, explains the specialist. As long as it is not in the body, there will be no consequence since it is part of the natural flora of man (except in immunodeficient people, or In addition to being transmitted in the hospital, it can enter the body by direct transmission: Staphylococcus aureus is often present in the nose. If the person touches or scratches their nose, the bacteria ends up on their fingers, then transfers to someone else by shaking hands, and it continues to spread that way until it gets in. in the body, through the mouth for example. It can infect any organ because Staphylococcus aureus is very virulent.
THE Staphylococcus epidermidis is a bacteria that are part of the mucocutaneous flora of almost the entire population. This means that we have it on our epidermis without it causing symptoms. The white staphylococcus can nevertheless become pathogenic in certain circumstances: in the event of immunodeficiency (AIDS, radiotherapy, chemotherapy, etc.) or during the implantation in the body of foreign bodies which have been contaminated by strains present in the patient himself or the nursing staff. It usually leads to skin-related pathologies.
The manifestations are just as diverse as the localizations where staphylococcus can infect the body. “It is a bacterium that can infect all organs, but above all causes boilsthat’s to say skin infections“. These skin infections can vary depending on their location:
- boil,
- onyxis,
- impetigo,
- stye,
- whitlow,
- folliculitis,
- erysipelas…
It can also be located in organs and infect bone tissue as in osteitis or osteomyelitis for example, joints as in spondylodiscitis in the intervertebral discs… In more serious cases, it can lead to meningitis, endocarditis etc “Depending on where it goes, it can bypass the body’s defences, break down tissues and lyse blood proteins to obtain iron.“, describes the specialist.
As said before, staphylococci can be transmitted in some cases by touching each other. But this does not necessarily mean that the person will be infected: for this, the bacteria must be able to penetrate the body. The bacterium being immobile, it cannot swim or move: it must arrive directly in the body to have an effect.
The bacteria enters the body when the skin barrier is broken (by injuries). The bacteria can then grow at the level of the lesion and cause a skin infection, the degree of severity of which will depend on the bacterial strain causing the infection, as well as the speed of treatment and the general state of health of the patient. . These infections are often of the suppurative type (with production of pus) and result from the proliferation of the bacteria. We can also catch it while eating: “Like all other bacteria, some produce a food toxin which, even cooked, remains toxic. This has been the source of many scandals. The toxin will remain in the food, but is relatively benign: it causes vomiting and diarrhea, but this generally only lasts 42 hours“.
“To begin with, we are alerted by the patient’s symptoms: if we see an infection with pus, we take a sample“, explains the specialist. Staphylococcus can be demonstrated by cultures in the laboratory, and according to its color, the type of staphylococcus will be identified. “A laboratory identification is then requested using an antibiogram, to assess the bacteria’s resistance to antibiotics.“, details the doctor. Depending on this result, we can prescribe a treatment.
“When the bacterium is multi-resistant, it is difficult to eliminate it”
Treatment for staph infection involves the use of antibiotics. Depending on its type, staphylococcus may be sensitive to antibiotics usually active on these germs, but it may also have developed resistance. “An over-prescription of antibiotics from the 1940s created resistance. As soon as we release new antibiotics, a few years later, certain bacteria become resistant“, explains Dr. Tarek Msadek. Performing an antibiogram, which makes it possible to test different antibiotics on cultures, will make it possible to determine this resistance and to set up an appropriate treatment. “If we treat with doses that are too low, we kill certain bacteria, but resistance appears and these will take over. However, when the bacterium is multi-resistant, it is difficult to eliminate it“, adds the specialist.
THE frequent and systematic hand washing and utensils used in the hospital environment helps prevent the transmission of staphylococcus, which may be pathogenic for one person, but not for another. In any case, it is essential to maintain constant hygiene and of disinfect any wound. Since the discovery of staphylococcus, there are a lot of disinfectants in hospitals: it is essential to use them. In addition, in a hospital setting, an infected patient will be placed in a single room, in isolation.
Thanks to Dr. Tarek Msadek, Head of the Department of Microbiology at the Institut Pasteur.