pneumococcal infection

肺炎球菌感染症

関

Streptococcus

WordNet

1. (medicine) the invasion of the body by pathogenic microorganisms and their multiplication which can lead to tissue damage and disease
2. (phonetics) the alteration of a speech sound under the influence of a neighboring sound
3. the pathological state resulting from the invasion of the body by pathogenic microorganisms
4. (international law) illegality that taints or contaminates a ship or cargo rendering it liable to seizure
5. moral corruption or contamination; "ambitious men are led astray by an infection that is almost unavoidable"
6. an incident in which an infectious disease is transmitted (同)contagion, transmission
7. of or derived from or caused by bacteria of the genus pneumococcus

PrepTutorEJDIC

1. 〈U〉(病気の)伝染;感染 / 〈C〉伝染病

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出典(authority):フリー百科事典『ウィキペディア（Wikipedia）』「2015/11/07 01:44:38」(JST)

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Pneumococcal infection
Classification and external resources
MeSH	D011008

Pneumococcal infection refers to an infection caused by Streptococcus pneumoniae.

Infections

Pneumococcal meningitis

S. pneumoniae is responsible for 15–50% of all episodes of community acquired pneumonia, 30–50% of all cases of acute otitis media and a significant proportion of bacteremia and bacterial meningitis.

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.

Pathogenesis

S. pneumoniae is normally found in the nose and throat of 5–10% of healthy adults, and 20–40% of healthy children. It can be found in higher amounts in certain environments, especially those where people are spending a great deal of time in close proximity to each other (day care centers, military barracks). It attaches to nasopharyngeal cells through interaction of bacterial surface adhesins. This normal colonization can become infectious if the organisms are carried into areas such as the Eustachian tube or nasal sinuses where it can cause otitis media and sinusitis, respectively. Pneumonia occurs if the organisms are inhaled into the lungs and not cleared (again, viral infection, or smoking-induced ciliary paralysis might be contributing factors). The organism's polysaccharide capsule makes it resistant to phagocytosis, and if there is no pre-existing anticapsular antibody, alveolar macrophages cannot adequately kill the pneumococci. The organism spreads to the blood stream (where it can cause bacteremia) and is carried to the meninges, joint spaces, bones, and peritoneal cavity, and may result in meningitis, brain abscess, septic arthritis, or osteomyelitis.

S. pneumoniae has several virulence factors, including the polysaccharide capsule mentioned earlier, that help it evade a host's immune system. It has pneumococcal surface proteins that inhibit complement-mediated opsonization, and it secretes IgA1 protease that will destroy secretory IgA produced by the body and mediates its attachment to respiratory mucosa.

The risk of pneumococcal infection is much increased in persons with impaired IgG synthesis, impaired phagocytosis, or defective clearance of pneumococci. In particular, the absence of a functional spleen, through congenital asplenia, splenectomy, or sickle-cell disease predisposes one to a more severe course of infection (Overwhelming post-splenectomy infection) and prevention measures are indicated (see asplenia).

People whose immune systems are compromised, such as those living with HIV, are also at higher risk of pneumococcal disease. 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%.

There is an association between pneumococcal pneumonia and influenza. Damage to the lining of the airways (respiratory epithelium) and upper respiratory system caused by influenza may facilitate pneumococcal entry and infection.

Other risk factors include smoking, injection drug use, Hepatitis C, and COPD.

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.

• 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)
• Pili—hair-like structures that extend from the surface of many strains of S. pneumoniae. They contribute to colonization of upper respiratory tract and increase the formation of large amounts of TNF by the immune system during sepsis, raising the possibility of septic shock
• 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

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 blood agar plates with added optochin antibiotic disk, they show alpha-hemolytic colonies and a clear zone of inhibition around the disk meaning they're sensitive to the antibiotic. Pneumococci are also bile soluble. Just like other streptococci, they are catalase-negative. A Quellung test can identify specific capsular polysaccharides.

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 false-positive. Better results are achieved with rapid 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. Chest X-rays can also be conducted to confirm an infection.

Prevention

Main article: Pneumococcal vaccine

Vaccines against Streptococcus pneumoniae are available.

Treatment

Throughout history, treatment relied primarily on β-lactam antibiotics. In the 1960s, nearly all strains of S. pneumoniae were susceptible to penicillin, but, since that time, there has been an increasing prevalence of penicillin 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 quinolones. 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 drug and concerns of development of vancomycin resistance. More advanced beta-lactam antibiotics (cephalosporins) are commonly used in combination with other drugs 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 drugs are used to treat tuberculosis, resistance has been described. Susceptibility testing should be routine, with empiric antibiotic treatment guided by resistance patterns in the community in which the organism was acquired, pending the results. There is currently debate as to how relevant the results of susceptibility testing are to clinical outcome. There is slight clinical evidence that penicillins may act synergistically with macrolides to improve outcomes.

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.

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.

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; the current vaccine contains 23 serovars (i.e., it is "23-valent").

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.

References

External links

• November 2nd: World Pneumonia Day Website
• Pneumococcal Vaccine Accelerated Development and Introduction Plan

UpToDate Contents

全文を閲覧するには購読必要です。 To read the full text you will need to subscribe.

• 1. 成人における肺炎球菌性肺炎 pneumococcal pneumonia in adults
• 2. 侵襲性肺炎球菌（Streptococcus pneumoniae）感染症および菌血症 invasive pneumococcal streptococcus pneumoniae infections and bacteremia
• 3. 成人における肺炎球菌ワクチン pneumococcal vaccination in adults
• 4. 小児の肺炎球菌性肺炎 pneumococcal pneumonia in children
• 5. β-ラクタム系抗菌薬に対する肺炎レンサ球菌の耐性 resistance of streptococcus pneumoniae to beta lactam antibiotics

English Journal

• Hemolytic Uremic Syndrome.

• Cody EM1, Dixon BP2.
• Pediatric clinics of North America.Pediatr Clin North Am.2019 Feb;66(1):235-246. doi: 10.1016/j.pcl.2018.09.011.
• PMID 30454746

• Long-term pneumococcal vaccine immunogenicity following allogeneic hematopoietic stem cell transplantation.

• Langedijk AC1, van Aalst M1, Meek B2, van Leeuwen EMM3, Zeerleder S4, Meijer E5, Hazenberg MD4, Grobusch MP1, Goorhuis A6.
• Vaccine.Vaccine.2019 Jan 14;37(3):510-515. doi: 10.1016/j.vaccine.2018.11.053. Epub 2018 Nov 27.
• PMID 30502071

• Regional variations in serotype distribution and vaccination status in children under six years of age with invasive pneumococcal disease in Germany.

• Perniciaro S1, Imöhl M1, Fitzner C2, van der Linden M1.
• PloS one.PLoS One.2019 Jan 9;14(1):e0210278. doi: 10.1371/journal.pone.0210278. eCollection 2019.
• PMID 30625215

Japanese Journal

• Pneumococcal biliary tract infections – How rare are they?

• Journal of Infection
• NAID 120006360041

• The contrasting roles of Th17 immunity in human health and disease

• Microbiology and immunology 61(2), 49-56, 2017-02
• NAID 40021166111

• 2007年以降に経験した急性乳様突起炎6症例の検討

• 日本耳鼻咽喉科感染症・エアロゾル学会会誌 = The journal of Japan Society for Infection
• NAID 40021099315

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★リンクテーブル★

リンク元	「肺炎球菌感染症」「肺炎球菌感染」「Streptococcus pneumoniae infection」「肺炎球菌性感染症」
関連記事	「infection」「pneumococcal」

「肺炎球菌感染症」

　　[★]

英

pneumococcal infection, pneumococcal infections, Streptococcus pneumoniae infection

同

肺炎球菌性感染症, 肺炎球菌感染, Streptococcus pneumoniae感染症

関

Streptococcus pneumoniae

「肺炎球菌感染」

　　[★]

英

pneumococcal infection、Streptococcus pneumoniae infection

関

肺炎球菌性感染症、肺炎球菌感染症、Streptococcus pneumoniae感染症

「Streptococcus pneumoniae infection」

　　[★]

肺炎球菌感染症、肺炎球菌感染、Streptococcus pneumoniae感染症

関

pneumococcal infection

「肺炎球菌性感染症」

　　[★]

英

pneumococcal infection

関

肺炎球菌感染症、肺炎球菌感染

「infection」

　　[★]

• n.

• 感染、伝染、感染症

関

contagion、infect、infectious disease、infestation、transmission、transmit

　 　 　 　 　 　 　

「pneumococcal」

　　[★]

• adj.

• 肺炎球菌の

関

pneumococci、pneumococcus、S. pneumoniae、Streptococcus pneumoniae