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Streptococcus pneumoniae (pneumococcus)

Commonly carried in the oropharyngeal area. Epidemiology: 1) peak incidence in the winter & spring 2) carrier rates as high as 70% or higher [4] -> penicillin-resistant pneumococci associated with beta- lactam antibiotic use [4] 3) infection most common in infants & elderly 4) risk factors: a) cardiopulmonary disease, especially pulmonary edema b) viral respiratory tract infections c) hemoglobinopathy d) hyposplenism e) immunosuppression 5) 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: 1) pneumonia a) chest X-ray 1] may initially be normal 2] later may show classic lobar pneumonia b) leukocytosis of 10,000-30,000/mm3 is common c) sputum may be rust colored or blood-streaked d) pleurisy/pleural effusion is common e) cavitation is rare f) Streptococcus pneumoniae may increase susceptibility to viral pneumonia [5] 2) bacteremia & sepsis, especially in the elderly a) mortality 20-30% b) fever in 70% c) respiratory distress in 50% d) altered mental status in 50% e) volume depletion in 50% 3) meningitis - mortality 20% 4) endocarditis 5) septic polyarthritis Genetics: -> M-phenotype produces an efflux pump resulting in resistance to: a) macrolides: erythromycin, clarithromycin, azithromycin -> 11% in 1995, 20% in 1999 b) sensitivity to clindamycin persists c) coresistance to other antibiotics is common -> penicillin (81%), cefotaxime (60%), Bactrim (88%) d) most M-phenotypes sensitive to fluoroquinolones e) risk factors include - older age, immunosuppression, alcoholism, beta-lactam within past 3 months, exposure to child in day care Laboratory: - Streptococcus pneumoniae serology - Streptococcus pneumoniae serotype - Streptococcus pneumoniae antigen - Streptococcus pneumoniae antigen in CSF - Streptococcus pneumoniae antigen in serum - Streptococcus pneumoniae antigen in sputum - Streptococcus pneumoniae antigen in urine - Streptococcus pneumoniae nucleic acid - Streptococcus pneumoniae DNA - Streptococcus pneumoniae gryB gene - Streptococcus pneumoniae lytA gene - Streptococcus pneumoniae nanA gene - Streptococcus pneumoniae rRNA - Streptococcus identified by culture a) Gram positive cocci in pairs (lancet-shaped diplococci) & chains. b) grows in 18-24 hours on ordinary blood agar incubated at 37 degrees in 5-10% CO2 c) colonies are alpha hemolytic & heterogenous in appearance d) may be identified by sensitivity to optochin - antibiotic resistance testing a) disk diffusion test with oxacillin predicts susceptibility to penicillin: b) some isolates resistant on disk diffusion will be sensitive by standard broth MIC testing c) susceptible: MIC < 0.1 ug/mL d) intermediate resistance: MIC 0.1-1.0 ug/mL e) resistant: MIC > 2.0 ug/mL - 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: 1) uncomplicated pneumonia treated as outpatient: a) procaine PCN G 600,000 units IM, followed by PCN V 250-500 mg PO every 6 hours for 7-10 days b) 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) c) penicillin allergy - macrolide - doxycycline - respiratory fluoroquinolone - clindamycin 2) seriously ill patients: a) PCN G 1-2 million units IV every 4 hours b) erythromycin 500 mg PO or IV every 6 hours if PCN allergy c) levofloxacin d) vancomycin 1 g IV every 12 hours if PCN allergy or PCN or multi-drug resistant organism (all strains sensitive to vancomycin) e) 2 drugs may be better that one for sepsis [6] - beta lactam/macrolide - beta lactam/vancomycin - beta lactam/aminoglycoside f) empiric therapy for meningitis - vancomycin + ceftriaxone + dexamethasone 3) 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]

Related

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 Streptococcus pneumoniae nucleic acid

Specific

penicillin resistant pneumococcus (PRP)

General

Streptococcus

Properties

KINGDOM: monera DIVISION: SCHIZOMYCETES

References

  1. Manual of Medical Therapeutics, 28th edition, Ewald & McKenzie (eds) Little, Brown & Co, 1995, pg 301
  2. Medical Knowledge Self Assessment Program (MKSAP) 11, 15, 16. American College of Physicians, Philadelphia 1998, 2009, 2012
  3. Mayo Internal Medicine Board Review, 1998-99, Prakash UBS (ed) Lippincott-Raven, Philadelphia, 1998, pg 796
  4. Journal Watch 22(4):29, 2002 Nasrin et al, BMJ 324:28, 2002
  5. 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: 15247911
  6. 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: 15184200
  7. ARUP Consult: Streptococcus pneumoniae The Physician's Guide to Laboratory Test Selection & Interpretation https://arupconsult.com/content/streptococcus-pneumoniae
  8. Sandvall B et al. Long-term survival following pneumococcal pneumonia. Clin Infect Dis 2013 Apr 15; 56:1145. PMID: 23300240
  9. 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: 20429967
  10. 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