Streptococcal infection

Streptococcal infection is a group of infectious diseases caused by streptococci of various serological groups, with airborne and alimentary transmission of the pathogen, occurring with fever, intoxication, local suppuration and the development of post-streptococcal autoimmune (rheumatism, glomerulonephritis) complications.

ICD-10 codes

• A38. Scarlet fever.
• A40. Streptococcal septicemia.
  • A40.0. Septicemia caused by group A streptococcus
  • A40.1. Septicemia caused by group B Streptococcus.
  • A40.2. Septicemia caused by group D streptococcus.
  • A40.3. Septicemia caused by Streptococcus pneumoniae.
  • A40.8. Other streptococcal septicemia.
  • A40.9. Streptococcal septicemia, unspecified.
• A46. The mug.
• A49.1. Streptococcal infection, unspecified.
• Q95. Streptococci and staphylococci as a cause of diseases classified elsewhere.
  • B95.0. Streptococcus group A as a cause of diseases classified elsewhere.
  • B95.1. Streptococcus group B as a cause of diseases classified elsewhere.
  • B95.2. Streptococcus group D as the cause of diseases classified elsewhere.
  • B95.3. Streptococcus pneumoniae as the cause of diseases classified elsewhere.
  • B95.4. Other streptococci as a cause of diseases classified elsewhere.
  • B95.5. Unspecified streptococci as a cause of diseases classified elsewhere.
• G00.2. Streptococcal meningitis.
• M00.2. Other streptococcal arthritis and polyarthritis.
• P23.3. Congenital pneumonia caused by group B Streptococcus.
• P23.6. Congenital pneumonia caused by other bacterial agents (streptococcus, except for group B).
• P36.0. Sepsis of the newborn caused by streptococcus group B.
• P36.1. Sepsis of the newborn, due to other and unspecified streptococci.
• Z22.3. Carrying out pathogens of other specified bacterial diseases (streptococci).

What causes streptococcal infection?

Streptococcal infection is caused by streptococci. The most important streptococcal pathogen is S. Pyogenes, it is beta-hemolytic, and in the Lancefield classification is assigned to group A. Thus, we get: beta-hemolytic streptococcus group A (HABGS).

What symptoms does streptococcal infection have?

The two most common acute diseases caused by group A beta-hemolytic streptococcus are pharyngitis and skin infections. In addition, delayed non-haemorrhagic complications such as acute rheumatic fever and acute glomerulonephritis sometimes appear 2 or more weeks after a streptococcal infection caused by Group A beta-hemolytic streptococcus. Diseases caused by other types of streptococci are usually less common and include soft tissue infection or endocarditis. Some non-HABCS infections predominantly occur in certain populations (eg, group B streptococcus in newborns and in infants, and enterococci in hospital patients).

Infections can spread along the length of affected tissues and through lymphatic channels into regional lymph nodes. There may also occur local purulent complications, such as peritonsillar abscess, otitis media, sinusitis. There may also be bacteremia. Whether there will be an abscess depends on the severity of the disease and the susceptibility of the affected tissue.

Streptococcal pharyngitis is usually caused by beta-hemolytic group A streptococcus. About 20% of patients with this disease have symptoms of strep throat infection, such as sore throat, fever, reddening of the pharynx and purulent deposits on the tonsils. In the remaining 80%, the symptoms of streptococcal infection are less pronounced, and the study reveals the same signs as in viral pharyngitis. Cervical and submaxillary lymph nodes may increase in size and become painful. Streptococcal pharyngitis can lead to peritonsillar abscess. Cough, laryngitis and stuffy nose are not characteristic for streptococcal pharyngeal infection. The presence of these symptoms usually indicates a disease of another etiology, most often viral or allergic. 20% of people are asymptomatic carriers of Group A beta-hemolytic streptococcus. Skin infections include impetigo and cellulite. Cellulite can spread very quickly. This is due to countless lytic enzymes that produce mainly group A streptococci. Erisipeloid is a particular case of cellulite.

Necrotizing fasciitis caused by pyogenic streptococcus is an acute cutaneous or rarely muscular infection that spreads along the fascial lintels. Streptococci with necrotizing fasciitis come from the skin or the viscera, and the damage can be surgical, trivial, remote from the disease site or blind, as with diverticulum of the colon and appendicular abscess. This disease often occurs in intravenous drug users. Formerly known as streptococcal gangrene and popularly called a meat-eating bacterium, the syndrome can also be polymicrobial when aerobic and anaerobic saprophyte flora, including Clostridium Perfringens, also participates in inflammation. When this syndrome captures the peritoneum, it is called gangrene Fournier. Frequent accompanying diseases, such as impaired immunity, diabetes and alcoholism. Symptoms of streptococcal infection begin with fever and intense local pain. Thrombosis of the microcirculatory bed causes ischemic necrosis, which leads to a rapid spread of infection and disproportionately increasing intoxication. In 20-40% of cases, adjacent muscles are involved in the process. Shock and renal dysfunction often occur. Even with adequate treatment, mortality is still high. Septicemia, purulent sepsis, endocarditis and pneumonia of streptococcal etiology remain serious complications, especially if the etiologic microorganism is multiresistant enterococcus.

Streptococcal infectious-toxic shock is similar to that caused by Staphylococcus aureus. It can be caused by toxin-producing strains of group A beta-hemolytic streptococcus. Patients are usually children and adults with skin infections or soft tissue infections that do not have other pathology.

Late complications of streptococcal infection

The mechanism of the appearance of late complications has not been studied in many respects, but it is known that cross-immunity reactions arise in which the formed antibodies to streptococcus antigens react with host tissues.

Acute rheumatic fever (ORL) is an inflammatory disorder. It occurs in less than 3% of patients within a few weeks after an untreated upper respiratory tract infection caused by Group A beta-hemolytic streptococcus. Today, acute rheumatic fever occurs much less frequently than in the pre-antibiotic era. The diagnosis is based on a combination of carditis, arthritis, chorea, specific skin manifestations and laboratory tests. The most important point in the treatment of streptococcal pharyngitis is the prevention of acute rheumatic fever.

Post-streptococcal acute glomerulonephritis is an acute nephritic syndrome that accompanies pharyngitis or skin infection caused by certain nephritogenic strains of group A beta-hemolytic streptococcus. This consequence can be caused only by a certain number of streptococcal group A serotypes. The overall frequency of attacks after a pharyngitis or skin infection is approximately 10-15%. Most often, it occurs in children 1-3 weeks after the disease. Almost all children recover and do not have permanent kidney disorders, but this is possible in some adults. Treatment of streptococcal infection with antibiotics does not have a significant effect on the formation of postreptococcal glomerulonephritis.

How is streptococcal infection diagnosed?

Streptococci are almost not identified by culture on a sheep blood agar. Tests of rapid detection of antigens are now available, which allows to determine beta-hemolytic streptococcus group A directly when studying smears from the throat. Many such tests are based on the methodology of immunoassays. Recently, optical immunological tests have become more accessible. They have a high sensitivity (more than 95%), but differ in specificity (50-80% and 80-90% for the most recent optical immunological tests). Negative results should be confirmed by culture research (in particular, when there is a question of using macrolides due to potential resistance). By the time of recovery, evidence of infection can be obtained indirectly by measuring the titers of anti-streptococcal antibodies in the blood serum. The detection of antibodies is very important for diagnosing post-streptococcal diseases, such as acute rheumatic fever and glomerulonephritis. Confirmation requires a consistent increase in antibody titres in the samples, since a single increase in antibody titers may result from a previous long-term infection. Serum samples should not be taken more than 2 weeks later, and they can be taken after 2 months. The titer of antistreptolysin-o (asl-o) increases only in 75-80% of cases of infection. For the full diagnosis in difficult cases, the following tests for the determination of: anti-hyaluronidase, antidexoxyribonuclease B, antinicotinamide adenine dinucleotide or antistreptokinase may be used. Penicillin, prescribed in the first five days after the onset of the disease for the symptomatic treatment of strep throat, may cause a later appearance and a decrease in the level of the asp response. Patients with streptococcal pyoderma usually do not give a significant response, but they can generate a response to other antigens (in particular, anti-DNAase or anti-hyaluronidase).

How is streptococcal infection treated?

Streptococcal pharyngitis

Pharyngeal beta-hemolytic group A streptococci infections are usually self-limiting. Prescribing antibiotics can reduce the duration of the disease in children, especially with scarlet fever, but have a weak effect on the development of symptoms in adults. Whatever the case, the use of antibiotics can prevent local purulent complications and acute rheumatic fever.

The drug of choice is penicillin. One injection of benzanthinopenicillin G 600 000 ED intramuscularly for young children (less than 27.3 kg) and 1.2 million units intravenously for adolescents and adults is often sufficient. Oral penicillin V can be used when there is confidence that the patient will withstand the required 10-day course and will follow the appointments. It is prescribed 500 mg of penicillin V (250 mg for children less than 27 kg). Oral cephalosporins are also effective. Cefdinir, cefpodoxime and azithromycin can be used for a 5-day course of therapy. Postponement of therapy for 1-2 days before the appearance of laboratory confirmation does not entail an increase in the duration of the disease and the incidence of complications.

In cases where penicillin and beta-lactam are contraindicated, erythromycin is administered 250 mg orally or clindamycin 300 mg orally for 10 days, but resistance of beta-hemolytic streptococcus group A to macrolides is noted (some authors recommend confirming in vitro sensitivity in those cases, when they are going to appoint a macrolide and there is a probability of resistance to macrolides in the community). Trimethoprim-sulfamethoxazole, some fluoroquinolones and tetracyclines are unreliable for the treatment of streptococcal infections. Clindamycin (5 mg / kg orally) is a more preferred drug in children with frequent exacerbations of chronic tonsillitis. Perhaps this is due to the fact that chronic tonsillitis causes co-infection in the crypts of the tonsils with penicillinase-producing staphylococci or anaerobes that inactivate penicillin G, and clindamycin has good activity against these agents. It also became known that clindamycin suppresses exotoxin production faster than other drugs.

Sore throat, fever, headache can be treated with analgesics and antipyretics. Bed rest and isolation are not necessary. Close contacts of people who have symptoms of streptococcal infection or a history of post-streptococcal complications should be studied for the presence of streptococci.

Skin Streptococcal Infections

Cellulite is often treated without performing a culture test. This is due to the fact that isolating the culture in this case is very difficult. Therefore, for the treatment of drugs that are effective not only for streptococci, but also for staphylococci. Necrotizing fasciitis should be treated in conditions of the DIC. It is necessary to conduct extensive (possibly, repeated) surgical scrubbing. The recommended starting antibiotic is betalactam (often a broad-spectrum preparation, until the etiology is confirmed by culture) plus clindamycin.

Despite the fact that staphylococci retain sensitivity to lactam antibiotics, animal studies have shown that penicillin is not always effective with a large bacterial inoculum, as streptococci grow slowly.

Other streptococcal infections

The drugs of choice for the treatment of infections caused by groups B, C and G are penicillin, ampicillin and vancomycin. Cephalosporins and macrolides are generally effective, but they should be prescribed taking into account the sensitivity of microorganisms, especially in severe patients, immunodeficient or weakened patients, and in people with foreign bodies in the focus of infection. Surgical drainage and wound cleaning as an addition to antimicrobial therapy can be salutary for a patient's life.

S. Bovis is relatively sensitive to antibiotics. Despite the fact that recently isolated vancomycin-resistant S. Bow's isolates, the microorganism remains sensitive to penicillin and aminoglycosides.

Most green streptococci are sensitive to penicillin G, and the rest - to lactams. Increased resistance, and therapy in the presence of such strains should be guided by the results of tests to determine the sensitivity in vitro.