Pneumococcal infection
Pneumococcal infection | |
---|---|
Other names | Pneumococcosis |
Respirology, neurology |
Pneumococcal infection is an infection caused by the bacterium Streptococcus pneumoniae.[1]
S. pneumoniae is a common member of the
Infections
As estimated by
Pathogenesis
S. pneumoniae is normally found in the
S. pneumoniae has several
The risk of pneumococcal infection is much increased in persons with impaired
People with a compromised immune system, such as those living with HIV, are also at higher risk of pneumococcal disease.[5] In HIV patients with access to treatment, the risk of invasive pneumoccal disease is 0.2–1% per year and has a fatality rate of 8%.[5]
There is an association between pneumococcal pneumonia and
Other risk factors include
Virulence factors
S. pneumoniae expresses different virulence factors on its cell surface and inside the organism. These virulence factors contribute to some of the clinical manifestations during infection with S. pneumoniae.[citation needed]
- Polysaccharide capsule—prevents phagocytosis by host immune cells by inhibiting C3b opsonization of the bacterial cells
- Pneumolysin (Ply)—a 53-kDa pore-forming protein that can cause lysis of host cells and activate complement
- Autolysin (LytA)—activation of this protein lyses the bacteria releasing its internal contents (i.e., pneumolysin)
- Hydrogen peroxide—causes damage to host cells (can cause apoptosis in neuronal cells during meningitis) and has bactericidal effects against competing bacteria (Haemophilus influenzae, Neisseria meningitidis, Staphylococcus aureus)[7][8]
- Choline binding protein A/Pneumococcal surface protein A (CbpA/PspA)—an adhesin that can interact with carbohydrates on the cell surface of pulmonary epithelial cells and can inhibit complement-mediated opsonization of pneumococci
- Competence for genetic transformation likely plays an important role in nasal colonization fitness and virulence (lung infectivity)[10]
Diagnosis
Depending on the nature of infection an appropriate sample is collected for laboratory identification. Pneumococci are typically gram-positive cocci seen in pairs or chains. When cultured on
Pneumococcal antigen (cell wall C polysaccharide) may be detected in various body fluids. Older detection kits, based on latex agglutination, added little value above Gram staining and were occasionally
Prevention
Due to the importance of disease caused by S. pneumoniae several vaccines have been developed to protect against invasive infection. The World Health Organization recommend routine childhood pneumococcal vaccination;[12] it is incorporated into the childhood immunization schedule in a number of countries including the United Kingdom,[13] United States,[14] and South Africa.[15]
Treatment
Throughout history treatment relied primarily on
More advanced beta-lactam antibiotics (
Susceptibility testing should be routine with empiric antibiotic treatment guided by resistance patterns in the community in which the organism was acquired. There is currently debate as to how relevant the results of susceptibility testing are to clinical outcome.[17][18] There is slight clinical evidence that penicillins may act synergistically with macrolides to improve outcomes.[19]
Resistant Pneumococci strains are called penicillin-resistant Pneumococci (PRP),[20] penicillin-resistant Streptococcus pneumoniae (PRSP),[21] Streptococcus pneumoniae penicillin resistant (SPPR),[22] or drug-resistant Strepotococcus pneumomoniae (DRSP).[23]
History
In the 19th century it was demonstrated that immunization of rabbits with killed pneumococci protected them against subsequent challenge with viable pneumococci. Serum from immunized rabbits or from humans who had recovered from pneumococcal pneumonia also conferred protection. In the 20th century, the efficacy of immunization was demonstrated in South African miners.[citation needed]
It was discovered that the pneumococcus's capsule made it resistant to phagocytosis, and in the 1920s it was shown that an antibody specific for capsular polysaccharide aided the killing of S. pneumoniae. In 1936, a pneumococcal capsular polysaccharide vaccine was used to abort an epidemic of pneumococcal pneumonia. In the 1940s, experiments on capsular transformation by pneumococci first identified DNA as the material that carries genetic information.[24]
In 1900 it was recognized that different
The serovars are numbered according to two systems: the American system, which numbers them in the order in which they were discovered, and the Danish system, which groups them according to antigenic similarities.[citation needed]
References
- ISBN 978-0-323-71159-3.
- ^ ISBN 0-8385-8529-9.
- ^ PMID 17380597.
- ^ Verma R, Khanna P (2012) Pneumococcal conjugate vaccine: A newer vaccine available in India. Hum Vaccin Immunother 8(9)
- ^ PMID 22078162.
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- PMID 16481624.
- PMID 27068094.
- ^ PMID 18260752.
- PMID 24340399.
- ^ "Children to be given new vaccine". BBC News. 8 February 2006.
- ^ "Pneumococcal Vaccination: Information for Health Care Providers". cdc.org. Retrieved 26 July 2016.
- ^ "Critical decline in pneumococcal disease and antibiotic resistance in South Africa". NICD. Archived from the original on 23 July 2015. Retrieved 20 July 2015.
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- ^ "Drug Resistance". cdc.gov. 2019-02-13. Retrieved 17 February 2019.
- PMID 19871359.