Streptococcus pneumoniae (pneumococcus)
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Introduction
Commonly carried in the oropharyngeal area.
Epidemiology
- peak incidence in the winter & spring
- carrier rates as high as 70% or higher[4]
- penicillin-resistant pneumococci associated with beta- lactam antibiotic use[4]
- infection most common in infants & elderly
- risk factors:
- Table: serotype frequency for years 2020 & 2021[10]
| serotype | 2020 | 2021 | |
|---|---|---|---|
| 10A | 16 | 5 | |
| 11A | 26 | 16 | |
| 12F | 6 | 7 | |
| 13 | 1 | 3 | |
| 14 | 3 | 0 | |
| 15A | 26 | 32 | |
| 15B | 11 | 10 | |
| 15C | 9 | 3 | |
| 16F | 22 | 23 | |
| 17F | 3 | 2 | |
| 18C | 0 | 2 | |
| 19A | 18 | 11 | |
| 19F | 15 | 14 | |
| 20 | 15 | 11 | |
| 21 | 1 | 1 | |
| 22F | 58 | 40 | |
| 23A | 23 | 38 | |
| 23B | 12 | 11 | |
| 23F | 1 | 0 | |
| 24F | 1 | 0 | |
| 28A | 1 | 3 | |
| 3 | 106 | 63 | |
| 31 | 12 | 12 | |
| 33F | 12 | 14 | |
| 34 | 9 | 7 | |
| 35B | 29 | 43 | |
| 35F | 10 | 21 | |
| 37 | 1 | 0 | |
| 38 | 3 | 0 | |
| 4 | 7 | 8 | |
| 6B | 0 | 2 | |
| 6C | 12 | 8 | |
| 7C | 14 | 13 | |
| 7F | 4 | 1 | |
| 8 | 18 | 8 | |
| 9N | 32 | 35 | |
| 9V | 1 | 0 | |
| mixed | 122 | 142 | |
| NT | 3 | 0 |
, mixed = mixed serotypes
Pathology
- pneumonia
- chest X-ray
- may initially be normal
- later may show classic lobar pneumonia
- leukocytosis of 10,000-30,000/mm3 is common
- sputum may be rust colored or blood-streaked
- pleurisy/pleural effusion is common
- cavitation is rare
- Streptococcus pneumoniae may increase susceptibility to viral pneumonia[5]
- chest X-ray
- bacteremia & sepsis, especially in the elderly
- mortality 20-30%
- fever in 70%
- respiratory distress in 50%
- altered mental status in 50%
- volume depletion in 50%
- meningitis - mortality 20%
- endocarditis
- septic polyarthritis
Genetics
- M-phenotype produces an efflux pump resulting in resistance to:
- macrolides: erythromycin, clarithromycin, azithromycin
- 11% in 1995, 20% in 1999
- sensitivity to clindamycin persists
- coresistance to other antibiotics is common
- penicillin (81%), cefotaxime (60%), Bactrim (88%)
- most M-phenotypes sensitive to fluoroquinolones
- risk factors include
- older age, immunosuppression, alcoholism, beta-lactam within past 3 months, exposure to child in day care
- macrolides: erythromycin, clarithromycin, azithromycin
Laboratory
- Streptococcus pneumoniae serology
- Streptococcus pneumoniae serotype
- Streptococcus pneumoniae antigen
- Streptococcus pneumoniae nucleic acid
- Streptococcus identified by culture
- Gram positive cocci in pairs (lancet-shaped diplococci) & chains.
- grows in 18-24 hours on ordinary blood agar incubated at 37 degrees in 5-10% CO2
- colonies are alpha hemolytic & heterogenous in appearance
- may be identified by sensitivity to optochin
- antibiotic resistance testing
- see ARUP consult[7]
Complications
- 1 month mortality men with mean age 63 years is 12%
- 10-year survival of patients with pneumococcal pneumonia, men with mean age 63 years is < 70%[8] (normal > 95%)[8]
Differential diagnosis
- Staphyloccus aureus unlikely cause of community-acquired pneumonia except after influenza, immunosuppression, injection drug use, male homosexuality
- Haemophilus influenzae is a less common cause of community-acquired pneumonia without chronic disease & is a less common cause of endocarditis & septic arthritis
- Borrelia burgdorferi generally does not cause pneumonia
Management
- uncomplicated pneumonia treated as outpatient:
- procaine PCN G 600,000 units IM, followed by PCN V 250-500 mg PO every 6 hours for 7-10 days
- amoxicillin 500 mg PO TID
- azithromycin preferred to amoxicillin for empiric therapy of community-acquired pneumonia in patients without risk factors for M-phenotype (see Genetics)
- penicillin allergy
- seriously ill patients:
- PCN G 1-2 million units IV every 4 hours
- erythromycin 500 mg PO or IV every 6 hours if PCN allergy
- levofloxacin
- vancomycin 1 g IV every 12 hours if PCN allergy or PCN or multi-drug resistant organism (all strains sensitive to vancomycin)
- 2 drugs may be better that one for sepsis[6]
- empiric therapy for meningitis
- resistance to penicillin
- arises via alterations in penicillin-binding protein(s)
- 50% of intermediate resistant strains are also resistant to ceftazidime & ceftizoxime
- most intermediate resistant strains are susceptible to ceftriaxone & cefotaxime
- most strains susceptible to respiratory fluoroquinolones
- vancomycin or linezolid[2]
More general terms
More specific terms
Additional terms
- pneumococcal congugate vaccine (Prevnar, Prevnar 13, PCV13, Prevnar-20, PCV20, Prevnar-15, PCV15, Vaxneuvance, Capavaxive, PCV21, PHiD-CV10, PCV10, Synflorix)
- pneumococcal vaccine
- pneumonia (PNA)
- recurrent invasive pneumococcal disease
References
- ↑ Manual of Medical Therapeutics, 28th edition, Ewald & McKenzie (eds) Little, Brown & Co, 1995, pg 301
- ↑ 2.0 2.1 Medical Knowledge Self Assessment Program (MKSAP) 11, 15, 16. American College of Physicians, Philadelphia 1998, 2009, 2012
- ↑ Mayo Internal Medicine Board Review, 1998-99, Prakash UBS (ed) Lippincott-Raven, Philadelphia, 1998, pg 796
- ↑ 4.0 4.1 4.2 Journal Watch 22(4):29, 2002 Nasrin et al, BMJ 324:28, 2002
- ↑ 5.0 5.1 Journal Watch 24(17):138, 2004 Madhi SA, Klugman KP, The Vaccine Trialist Group. A role for Streptococcus pneumoniae in virus-associated pneumonia. Nat Med. 2004 Aug;10(8):811-3. Epub 2004 Jul 11. PMID: https://www.ncbi.nlm.nih.gov/pubmed/15247911
- ↑ 6.0 6.1 Journal Watch 24(18):147, 2004 Baddour LM, Yu VL, Klugman KP, Feldman C, Ortqvist A, Rello J, Morris AJ, Luna CM, Snydman DR, Ko WC, Chedid MB, Hui DS, Andremont A, Chiou CC; International Pneumococcal Study Group. Combination antibiotic therapy lowers mortality among severely ill patients with pneumococcal bacteremia. Am J Respir Crit Care Med. 2004 Aug 15;170(4):440-4. Epub 2004 Jun 07. PMID: https://www.ncbi.nlm.nih.gov/pubmed/15184200
- ↑ 7.0 7.1 ARUP Consult: Streptococcus pneumoniae The Physician's Guide to Laboratory Test Selection & Interpretation https://arupconsult.com/content/streptococcus-pneumoniae
- ↑ 8.0 8.1 8.2 Sandvall B et al. Long-term survival following pneumococcal pneumonia. Clin Infect Dis 2013 Apr 15; 56:1145. PMID: https://www.ncbi.nlm.nih.gov/pubmed/23300240
- ↑ Wong A, Marrie TJ, Garg S et al Increased risk of invasive pneumococcal disease in haematological and solid-organ malignancies. Epidemiol Infect. 2010 Dec;138(12):1804-10. PMID: https://www.ncbi.nlm.nih.gov/pubmed/20429967
- ↑ 10.0 10.1 Centers for Disease Control & Prevention Public Health Surveillance. September 29, 2023 2016-2021 Serotype Data for Invasive Pneumococcal Disease Cases by Age Group from Active Bacterial Core surveillance https://data.cdc.gov/Public-Health-Surveillance/2016-2021-Serotype-Data-for-Invasive-Pneumococcal-/qvzb-qs6p