Pneumococcal infection

Source: Wikipedia, the free encyclopedia.
Pneumococcal infection
Other namesPneumococcosis
Respirology, neurology

Pneumococcal infection is an infection caused by the bacterium Streptococcus pneumoniae.[1]

S. pneumoniae is a common member of the

nose and throat of 5–10% of healthy adults and 20–40% of healthy children.[2] However, it is also a cause of significant disease, being a leading cause of pneumonia, bacterial meningitis, and sepsis. The World Health Organization estimates that in 2005 pneumococcal infections were responsible for the death of 1.6 million children worldwide.[3]

Infections

Pneumococcal meningitis

bloodstream infections and bacterial meningitis.[4]

As estimated by

WHO in 2005 it killed about 1.6 million children every year worldwide with 0.7–1 million of them being under the age of five. The majority of these deaths were in developing countries.[3]

Pathogenesis

S. pneumoniae is normally found in the

bacteremia) and is carried to the meninges, joint spaces, bones, and peritoneal cavity, and may result in meningitis, brain abscess, septic arthritis, or osteomyelitis.[citation needed
]

S. pneumoniae has several

IgA produced by the body and mediates its attachment to respiratory mucosa.[citation needed
]

The risk of pneumococcal infection is much increased in persons with impaired

sickle-cell disease predisposes one to a more severe course of infection (overwhelming post-splenectomy infection) and prevention measures are indicated.[citation needed
]

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

upper respiratory system
caused by influenza may facilitate pneumococcal entry and infection.

Other risk factors include

COPD.[5]

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]

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

Quellung test can identify specific capsular polysaccharides.[11]

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

immunochromatography, which has a sensitivity (identifies the cause) of 70–80% and >90% specificity (when positive identifies the actual cause) in pneumococcal infections. The test was initially validated on urine samples but has been applied successfully to other body fluids.[11] Chest X-rays can also be conducted to confirm inflammation though are not specific to the causative agent.[citation needed
]

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

resistance especially in areas of high antibiotic use. A varying proportion of strains may also be resistant to cephalosporins, macrolides (such as erythromycin), tetracycline, clindamycin and the fluoroquinolones. Penicillin-resistant strains are more likely to be resistant to other antibiotics. Most isolates remain susceptible to vancomycin, though its use in a β-lactam-susceptible isolate is less desirable because of tissue distribution of the medication and concerns of development of vancomycin resistance.[citation needed
]

More advanced beta-lactam antibiotics (

cephalosporins) are commonly used in combination with other antibiotics to treat meningitis and community-acquired pneumonia. In adults recently developed fluoroquinolones such as levofloxacin and moxifloxacin are often used to provide empiric coverage for patients with pneumonia, but in parts of the world where these medications are used to treat tuberculosis, resistance has been described.[16]

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

serovars of pneumococci exist and that immunization with a given serovar did not protect against infection with other serovars. Since then over ninety serovars have been discovered each with a unique polysaccharide capsule that can be identified by the quellung reaction. Because some of these serovars cause disease more commonly than others it is possible to provide reasonable protection by immunizing with less than 90 serovars; current vaccines contain up to 23 serovars (i.e., it is "23-valent").[citation needed
]

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

  1. .
  2. ^ .
  3. ^ .
  4. ^ Verma R, Khanna P (2012) Pneumococcal conjugate vaccine: A newer vaccine available in India. Hum Vaccin Immunother 8(9)
  5. ^
    PMID 22078162
    .
  6. .
  7. .
  8. .
  9. .
  10. .
  11. ^ .
  12. .
  13. ^ "Children to be given new vaccine". BBC News. 8 February 2006.
  14. ^ "Pneumococcal Vaccination: Information for Health Care Providers". cdc.org. Retrieved 26 July 2016.
  15. ^ "Critical decline in pneumococcal disease and antibiotic resistance in South Africa". NICD. Archived from the original on 23 July 2015. Retrieved 20 July 2015.
  16. S2CID 205950081
    .
  17. .
  18. .
  19. .
  20. .
  21. .
  22. .
  23. ^ "Drug Resistance". cdc.gov. 2019-02-13. Retrieved 17 February 2019.
  24. PMID 19871359
    .

External links