Cocci occur in several organizational forms and can lead to serious infections if they multiply rapidly and the infected person has a weakened immune system. Several cocci subspecies are so adaptable that they have now evolved strains that are resistant to conventional antibiotics. It is also particularly insidious that cocci can repeatedly cause severe food poisoning despite good food hygiene.
What are cocci?
Cocci are spherical bacteria that are either completely round or egg-shaped or elliptical in shape. The medical layperson can tell that certain types of bacteria are cocci by the name ending -coccus. Cocci occur in various forms of organization, depending on the level of division at which they have not separated from one another. The best-known representatives are staphylococci, streptococci and enterococci. If the bacteria, which are normally present in every human and animal, encounter particularly favorable conditions and multiply rapidly, they can trigger dangerous diseases and even lead to death. Immunocompromised individuals, diabetics, neurodermatitis sufferers and hospitalized persons (patients and hospital staff) are particularly at risk of contracting cocci infections. In most cases, cocci are treated with the usual antibiotics. However, there are now strains that are resistant to certain antibiotics. Staphylococci were first described by Friedrich Julius Rosenbach in 1884. Enterococci were previously considered to be serogroup D streptococci because, like streptococci, they have the group D Lancefield antigen. Since 1984, however, they have been considered a distinct genus of cocci because of their divergent genetic structure. They belong to the lactobacilli (lactic acid bacteria).
Occurrence, distribution, and characteristics
The spherical bacteria are organized in groups of two (diplococci), tetrads (groups of four), or as chain cocci, parcel cocci (quadrangular aggregation of 8 or more spherical bacteria), or cluster cocci (in racemes). Staphylococci occur as clusters and colonize the surfaces of skin and mucous membranes in large numbers – but this does not bother people with intact immune systems. The gram-positive pathogens do not have any movement of their own and feed on putrefactive substances (saprophagous). Since they have a high pH tolerance, some disinfectants cannot kill them. Even desiccation cannot harm them. Because they can adapt quickly to new environments through mutation, they spread rapidly and can cause epidemics. Transmission occurs from person to person through direct contact with an infected person, through infected objects and food. The incubation period after infection with staphylococci is 4 to 10 days. Infected patients may also show symptoms months later. In cases of food poisoning, the first signs of illness appear after a few hours. The most important representatives are Staphylococcus aureus, which colonizes the skin and mucous membranes, and Staphylococcus epidermidis, which lives on the skin and other surfaces and is feared in hospitals because of its resistance to penicillin and methicillin. It is transmitted there via infected equipment, blood, cough secretions, wound secretions and skin contact. It enters the patient’s body via transplanted heart valves, artificial joints, and through indwelling venous catheters. Streptococci colonize the oral cavity and are usually harmless. The gram-positive spherical bacteria organize themselves individually or in pairs in more or less long chains. They cannot move on their own and do not form spores. Some strains are surrounded by a mucus envelope. They live anaerobically, but can be exposed to oxygen and are formed by fermentation processes. Enterococci also form chains and are part of the normal intestinal flora in animals and humans. They are also found in foods such as cheese and sausage.
Diseases and ailments
Staphylococcus aureus enters the bloodstream through wounds and injuries. Externally, it causes eczema, boils, and carbuncles. If it spreads through the bloodstream, it can cause heart and lung infections, hepatitis, meningitis, and even blood poisoning. Patients with a damaged skin barrier (neurodermatitis sufferers) and people with circulatory disorders of the skin are particularly at risk.Staphylococcus aureus strains, which are now resistant due to excessive use of antibiotics (MRSA strains), are particularly problematic. Toxic shock syndrome (circulatory failure due to explosive multiplication of staphylococci in the body) is also very dangerous for the patient. In addition, staphylococci can cause food poisoning, since even heat treatment does not completely kill the pathogens. Some strains are even insensitive to heat. Staphylococcus epidermidis readily attaches itself to foreign materials and thus, despite adequate disinfection, enters the patient’s body, where it can cause infections and even blood poisoning. Elderly people with heart disease and weakened immune defenses as well as recently operated patients are particularly at risk. After amputations, the invading bullet bacteria delay the healing process. Streptococci cause caries by attacking tooth enamel and are responsible for many infections in the ENT area such as middle ear and tonsillitis. They are also thought to cause pneumonia, purulent connective tissue infections (phlegmon), impetigo, wound and urinary tract infections, scarlet fever, puerperal fever, and toxic shock syndrome (TSS). Streptococci can usually be treated well with penicillin. Enterococci can cause chronic urinary tract inflammation if they enter the urinary tract organs from the intestines. They can also cause pleurisy and endocarditis. They are treated with a combination of aminopenicillin and aminoglycosides or, if resistant to penicillin or oxacillin, with a combination of ampicillin and gentamycin.
