Pneumococci

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Pneumococci
Streptococcus pneumoniae

Streptococcus pneumoniae

Systematics
Department : Firmicutes
Class : Bacilli
Order : Lactobacillales
Family : Streptococcaceae
Genre : Streptococcus
Type : Pneumococci
Scientific name
Streptococcus pneumoniae
( Klein 1884) Chester 1901

Pneumococci , Germanised plural from the latinisierten singular pneumococcus ( Alt Gr. Πνεύμων Pneumon , lungs 'and κόκκος KOKKOS , core', 'grain') are Gram-positive bacteria of the type pneumoniae Streptococcus which morphologically to the group of Diplo cocci are so mounted in pairs are.

Pathogen

S. pneumoniae are gram-positive bacteria with capsules . The polysaccharide capsule gives the pathogen an important virulence factor ; in addition, over 90 serotypes are known due to the various polysaccharides contained in it.

The colonies of encapsulated strains show a slimy sheen: S-shapes (“smooth”: smooth). Capsules make phagocytosis of the pneumococci more difficult : only S forms are virulent. The virulence of the pneumococci is proportional to the thickness of the capsule. Pneumococci, which are particularly rich in capsule substance, are therefore highly virulent. Severe pneumococcal diseases are triggered by capsule types that do not activate complement via the alternative route: They escape complement-mediated phagocytosis, which is particularly disadvantageous in the early phase of infection, i.e. H. before antibody formation.

Colonies of unencapsulated trunks are dull, they appear rough ("rough": rough). R-forms are avirulent.

Route of infection and clinical picture

Pneumococci can be passed on from person to person by smear infection , but most of the time it is an endogenous infection. They colonize the mucous membranes of the nasopharynx ( nasopharynx ). Carriers and vectors of pneumococci are mainly children in the first two years of life, adults without contact with small children are only about 5% colonized, a number that increases with age (> 65 years) and with a weaker immune system . Transmitters are usually colonized by one to a maximum of three different serotypes at the same time, which are, however, repeatedly replaced by new ones. The transmission also takes place via droplet infection .

A colonization with pneumococci in the nasopharynx is usually symptom-free and without clinical picture (possibly a slight cold). However, they bind the body's own defenses and disrupt the defense mechanisms. In the upper respiratory tract , the pathogen has to defend itself against elimination through mucociliary clearance . The pneumolysin released during the autolysis of the pneumococci, which acts as a cholesterol-dependent cytolysin through the formation of transmembrane pores in the cell membrane of its target cells, is able to inhibit this defense mechanism and destroy ciliate-bearing epithelial cells . Likewise, pneumolysin can granulocytes and lymphocytes affect functional and lyse in higher doses by pore formation. The polysaccharide capsule inhibits phagocytosis. The IgA1 protease secreted by pneumococci can support the establishment on the mucous membrane by breaking down IgA antibodies.

If pneumococci spreads to the upper or lower respiratory tract, it can cause sinus infections , middle ear infections, or pneumonia . Depending on the serotype, pneumococci can also trigger so-called "invasive pneumococcal diseases" (IPD). This means that they can be found in normally sterile body fluids such as B. be detected in the blood or in the cerebrospinal fluid . Pneumococci can implant themselves in red blood cells in order to avoid detection by neutrophils (white blood cells) - and thus contribute to an increased risk of infection, especially through viral infections with chronic diseases, especially in old age. This also promotes the spread of the bacterium. Inflammation of the middle ear, paranasal sinuses, lungs or meninges can then result, while a transition into the bloodstream (usually via previous infection of the lungs) leads to sepsis ( blood poisoning ). However, the exact reasons why colonization leads to life-threatening diseases in certain people, while most show no symptoms, are not fully understood. The most populated population groups, such as children in their first two years of life (immune systems not yet fully adapted), and the elderly, are at high risk.

Pneumococci can cause a wide variety of diseases. They can be particularly dangerous for babies, young children, the elderly and people with underlying chronic diseases.

Most people suffering from pneumonia sick (pneumonia), are over 50 years old. This is also particularly dangerous because it is easily overlooked. Typical symptoms of the disease, such as sudden high fever, chills, cough, and purulent sputum, are less common in old age. Pneumonia typically begins after a previous infection of the upper respiratory tract .

In addition to coughing, infants often show atypical symptoms such as poor drinking or runny nose. Young children have a cough, rapid pulse, are pale, and have a fever.

A meningitis (meningitis) is generally preceded by an infection of the upper respiratory tract. In infancy , children have a high fever, vomit, are apathetic or restless, refuse to eat or suffer from seizures. If the children are older than one year, the typical stiff neck (meningism) occurs, as well as headaches and unconsciousness . Even if the child survives the infection, they may retain brain damage, be deaf, or have poor vision. In children under five years of age, pneumococci are the second most common cause of acute bacterial meningitis.

A middle ear infection (otitis media) causes severe ear pain and fever in affected children . Some children suffer from frequent otitis media. In Germany, it is estimated that 300,000 to 600,000 children under the age of five develop acute otitis media every year.

In the case of sinusitis (sinusitis), fever and headache occur and the sinuses are suppurated. Infants rarely develop inflammation of the maxillary sinuses because they are not yet fully developed. The so-called ethmoid cell system can also be affected in them.

A corneal inflammation pneumococcal often proceeds rapidly penetrating and painful ( ulcus serpens ).

Epidemiology

Before the pneumococcal vaccine spread in 2006, 6 to 11 serotypes were responsible for at least 70% of IPD in children under 5 years of age. At that time, the incidence of IPD in children under 2 years of age was 44.4 (Europe), 167 (USA), 60 (South Africa) up to 797 ( Mozambique ) per 100,000 per year. According to official estimates by the WHO , around 1.6 million people died from pneumococcal infections in 2005, including an estimated 826,000 children under the age of 5 in the early 2000s. In 2008 the number of deaths fell to around 476,000 children under 5 years of age, in 2015 to 294,000 or 317,300 if co-infections with HIV are counted.

In Germany, more than 10,000 people fall victim to pneumococcal pneumonia every year. Despite antibiotics , half of these deaths occur within the first 48 hours. In the acute phase, the mortality rate is around eight percent, and in the following months around another five percent. [Document is missing]

There is no compulsory registration nationwide, but in some federal states such as Saxony-Anhalt, Saxony, Mecklenburg-Western Pomerania, Brandenburg and Thuringia there is an obligation to register for IPD due to state regulations.

Diagnosis

Pneumococci can be detected microscopically and culturally in corresponding test samples (blood, sputum, bronchial secretions, liquor). They show α-hemolysis on blood agar. There is also a rapid test that detects pneumococcal antigen in the urine.

therapy

Despite the globally increasing antibiotic resistance , penicillins are still the first choice for the treatment of pneumococcal infections. In Germany in particular, the resistance situation of pneumococci to narrow-spectrum penicillins is extremely favorable, which is why targeted and guideline-based therapy, e.g. B. is indicated with penicillin G. The use of aminopenicillins also offers advantages, as they are also effective against germs that are important for differential diagnosis, such as Haemophilus influenzae . Pneumococcal meningitis is an exception , as penicillins, which are poorly accessible to liquor, do not achieve sufficiently high doses of active ingredient at the focus of inflammation. If pneumococcal meningitis is suspected, therapy with cephalosporins should be started immediately . Rifampicin and vancomycin are available as reserve antibiotics for penicillin-resistant pneumococcal strains . For post-exposure prophylaxis (at asplenischen chemotherapy with patients takes place) penicillin V .

vaccination

Two pneumococcal vaccines are available for the vaccination against pneumococci used for infection prophylaxis. A so-called polysaccharide vaccine (PPV23) has been available for many years and is primarily intended for older children and adults. It contains antigens of 23 different types of pneumococci, which are responsible for 90 percent of diseases (trade name Pneumovax 23).

A conjugated vaccine was approved in February 2001 under the trade name Prevenar ( Prevnar in other countries ) and is intended for young children. This is now directed against the ten most common types of pneumococci that are dangerous for children ( Synflorix ). In 2009, another conjugated vaccine, expanded to include 13 serotypes, was approved under the trade name Prevenar13 . This has been approved for all age groups since March 2015.

Before the conjugate vaccine was introduced, the pneumococcal vaccine was only available for children over the age of three, adolescents and adults. The polysaccharide vaccine that is suitable for them, however, is not sufficiently effective in infants and young children because it consists of the unchanged sugar molecules in the capsule and also has weaknesses in long-term effectiveness in adults. Therefore, children under two years of age could not previously be vaccinated against pneumococcal infections. A trick was used in the manufacture of the conjugate vaccine. A protein molecule was bound to the capsule sugar molecules, which makes it easier for the white blood cells to recognize the pathogen. A conjugate vaccine has also been available in Germany since March 2001, which can be used successfully in infants and young children. More than 37,000 young children were vaccinated in clinical studies in the United States and Finland. The effectiveness of the new vaccine was proven in the selected target group.

Although the vaccination is well tolerated, only a small proportion of the people for whom it is recommended are vaccinated. In particular, it is hoped that the vaccination will curb the emergence of antibiotic resistance, which makes it difficult to treat pneumococcal infections worldwide. Therefore, some authorities demand that vaccination should be used to a greater extent than before.

Pneumococcal vaccination protects against invasive pneumococcal infections. On the cost-benefit ratio: A research group at Maastricht University led by Silvia Evers has calculated the cost-benefit ratio of pneumococcal vaccination with a 23-valent polysaccharide vaccine. The upper limit is 50,000 euros per year of life of the same quality (QALY; 1 QALY corresponds, in short, to a year of life spent in perfect health). Health economists consider measures that cost less than 50,000 euros per QALY to be cost-effective. Evers' analysis extended to ten European countries. The cost-benefit ratios were between 9,239 (Denmark) and 23,657 euros per QALY (Sweden). In these calculations, Germany ranks in the middle with 17,093 euros per QALY.

A Dutch research group found that the 7-valent conjugate vaccination PCV-7, known under the trade name Prevnar® , had spread the pneumococcal serotype 19A in the USA and the Netherlands. Serotype 19A is not covered by the 7-valent conjugate vaccine; only the 13-valent conjugate vaccine Prevnar 13® also contains conjugated antigens of the pneumococcal serotype 19A.

Reporting requirement

In Germany, direct evidence of Streptococcus pneumoniae must be reported by name in accordance with Section 7 of the Infection Protection Act (IfSG), provided that the evidence indicates an acute infection and the evidence was obtained from liquor, blood, joint aspirate or other normally sterile substrates . The obligation to notify primarily concerns the management of laboratories ( § 8 IfSG).

In Switzerland, the positive laboratory analysis of Streptococcus pneumoniae or an invasive pneumococcal disease for laboratories, doctors, hospitals, etc. must be reported according to the Epidemics Act (EpG) in conjunction with the Epidemics Ordinance and Appendix 3 or Appendix 1 of the Ordinance of the FDHA on the reporting of observations of communicable diseases in humans .

Web links

Commons : Streptococcus pneumoniae  - album with pictures, videos and audio files
Wiktionary: Pneumococci  - explanations of meanings, word origins, synonyms, translations

Individual evidence

  1. ^ Wilhelm Gemoll : Greek-German school and hand dictionary. Munich / Vienna 1965.
  2. ↑ a b c d e f Epidemiological Bulletin : Scientific justification for updating the pneumococcal vaccination recommendation for seniors. RKI, December 12, 2016, accessed November 24, 2019 .
  3. ↑ a b c Prof. Dr. Sören Gatermann: Medical Microbiology and Infectiology . Ed .: Suerbaum, Burchard, Kaufmann, Schulz. 8th edition. Springer, Berlin, Heidelberg 2016, ISBN 978-3-662-48677-1 , pp. 205 .
  4. ↑ Masaya Yamaguchi et al .: Streptococcus pneumoniae Invades Erythrocytes and Utilizes Them to Evade Human Innate Immunity . In: PLOS ONE . tape 8 , no. 10 , 23 October 2013, ISSN  1932-6203 , p. e77282 , doi : 10.1371 / journal.pone.0077282 , PMID 24194877 , PMC 3806730 (free full text).
  5. ↑ a b Position paper on pneumococcal conjugate vaccines (PCV) - February 2019. World Health Organization , February 22, 2019, pp. 85-104 , accessed on November 24, 2019 .
  6. ↑ Pneumococcal disease. WHO , accessed November 24, 2019 .
  7. ^ Katherine L. O'Brien et al .: Burden of disease caused by Streptococcus pneumoniae in children younger than 5 years: global estimates . In: Lancet (London, England) . tape 374 , no. 9693 , September 12, 2009, p. 893-902 , doi : 10.1016 / S0140-6736 (09) 61204-6 , PMID 19748398 .
  8. ↑ Pneumococcal vaccines WHO position paper - 2012. World Health Organization , April 6, 2012, accessed on November 24, 2019 .
  9. ^ R. Gross: Pneumococci. In: The resident doctor. 1, 2014.
  10. ^ RR Reinert: The antimicrobial resistance profile of Streptococcus pneumoniae . In: Clinical Microbiology and Infection . tape 3 , April 2009, p. 7-11 , PMID 19366363 .
  11. ↑ GERMAP 2010. Retrieved December 15, 2011 .
  12. ↑ ZCT 5-2004: Streptococcus pneumoniae. ( Memento from October 24, 2010 in the Internet Archive )
  13. ^ Marianne Abele-Horn: Antimicrobial Therapy. Decision support for the treatment and prophylaxis of infectious diseases. With the collaboration of Werner Heinz, Hartwig Klinker, Johann Schurz and August Stich, 2nd, revised and expanded edition. Peter Wiehl, Marburg 2009, ISBN 978-3-927219-14-4 , pp. 320m and 322.
  14. ↑ Marianne Abele-Horn (2009), p. 326 f.
  15. ^ Pfizer Inc .: Pfizer Receives European Approval for New Indication for Prevenar 13. Pfizer , March 3, 2015, accessed July 31, 2015 .
  16. ↑ Steven B. Black et al .: Effectiveness of heptavalent pneumococcal conjugate vaccine in children younger than five years of age for prevention of pneumonia . In: The Pediatric Infectious Disease Journal . tape 21 , no. 9 , September 2002, p. 810-815 , doi : 10.1097 / 00006454-200209000-00005 , PMID 12352800 .
  17. ↑ More benefits than costs. In: Medical Practice. August 5, 2008, p. 6.
  18. ↑ Elske JM van Gils et al .: Pneumococcal conjugate vaccination and nasopharyngeal acquisition of pneumococcal serotype 19A strains . In: JAMA . tape 304 , no. 10 , September 8, 2010, p. 1099-1106 , doi : 10.1001 / jama.2010.1290 , PMID 20823436 .