Streptococcus pneumoniae: Difference between revisions

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Streptococcus pneumoniae
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== Background ==
 +
==Background==
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=== Microbiology ===
 +
===Microbiology===
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* [[Has Gram stain::Gram-positive]], lancet-shaped diplococci
  
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* 90+ serotypes, based on capsular polysaccharide that is bound to peptidoglycan
  
−
* Lab identification is based on [[Has hemolysis pattern::α-hemolysis]] of blood agar (from pneumolysin), [[Has susceptibility to::optochin]] susceptibility, and bile salt solubility
  
−
* Via transformation, bacteria can exchange genetic material with each other
  
   
  +
*[[Stain::Gram-positive]], lancet-shaped [[Shape::coccus|diplococcus]]
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==== Susceptibility testing ====
  
  +
*90+ serotypes, based on capsular polysaccharide that is bound to peptidoglycan
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* CLSI penicillin breakpoints for susceptibility changed in 2008
  
  +
*Lab identification is based on catalase [[Catalase::negative]], [[Hemolysis pattern::α]] hemolysis of blood agar (from pneumolysin), [[Susceptible to::optochin]] susceptibility, and bile salt solubility
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** For meningitis: ≤0.06 μg/mL
  
  +
*Via transformation, bacteria can exchange genetic material with each other
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** For other infections: ≤2 μg/mL
  
   
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==== Antibiotic resistance ====
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===Antibiotic Resistance===
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* '''[[Penicillin]]''' resistance
  
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** ''S. pneumoniae'' has 6 PBPs: 1A, 1B, 2A, 2B, 2X, and 3
  
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** Resistance in any of the PBPs can increase the MIC
  
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** Mutations in PBP 2B are associated with low-level resistance
  
−
** Mutations in PBP 2X are associated with high-level resistance
  
−
* '''[[Macrolides|Macrolide]]''' resistance
  
−
** ''ermB'' encodes an enzyme that methylates the 23S subunit, blocking macrolides and giving very high MIC ≥64
  
−
** ''mefA'' encodes an efflux pump that gives a relatively lower MIC ≤16
  
   
  +
*'''[[Penicillin]]''' resistance
−
=== Epidemiology ===
  
  +
**''S. pneumoniae'' has 6 PBPs: 1A, 1B, 2A, 2B, 2X, and 3
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* Present worldwide
  
  +
**Resistance in any of the PBPs can increase the MIC
−
* Major cause of morbidity and mortality in children
  
  +
**Mutations in PBP 2B are associated with low-level resistance
−
** Leading cause of under-5 mortality worldwide
  
  +
**Mutations in PBP 2X are associated with high-level resistance
  +
*'''[[Macrolides|Macrolide]]''' resistance
  +
**''ermB'' encodes an enzyme that methylates the 23S subunit, blocking macrolides and giving very high MIC ≥64
  +
**''mefA'' encodes an efflux pump that gives a relatively lower MIC ≤16
   
−
=== Pathophysiology ===
 +
===Epidemiology===
−
* Acquired by coughing and sneezing
  
−
* Asymptomatic carriage or colonization in the nasopharynx
  
−
* Invasion through epithelial cells into the bloodstream, using the PAF and pIg receptors
  
−
* Capsule and various proteins help it to evade immune system
  
   
  +
*Present worldwide
−
== Clinical Presentation ==
  
  +
*Major cause of morbidity and mortality in children
  +
**Leading cause of under-5 mortality worldwide
   
−
=== Asymptomatic carriage ===
 +
===Pathophysiology===
   
  +
*Acquired by coughing and sneezing
−
* 4-10% in the general adult population, usually lasting several weeks
  
  +
*Asymptomatic carriage or colonization in the nasopharynx
−
* Highest in children, up to 30-60% depending on the situation, lasting up to 6 months
  
  +
*Invasion through epithelial cells into the bloodstream, using the PAF and pIg receptors
  +
*Capsule and various proteins help it to evade immune system
   
  +
==Clinical Manifestations==
−
=== Otitis media ===
  
   
−
=== Sinusitis ===
 +
===Asymptomatic Carriage===
   
  +
*4-10% in the general adult population, usually lasting several weeks
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=== Bacteremia ===
  
  +
*Highest in children, up to 30-60% depending on the situation, lasting up to 6 months
   
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=== Pneumonia ===
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===Otitis Media===
   
  +
===Sinusitis===
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* Acute onset of cough (92%), fatigue (63%), shortness of breath (47%), and dyspnea (23%) with documented or subjective fever (92%), chills (77%), sweats, purulent sputum, and pleuritic chest pain (79%)
  
   
−
=== Meningitis ===
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===Bacteremia===
   
  +
===Pneumonia===
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* Most common cause of meningitis in adults
  
−
* Acquired by hematogenous spread from nasopharynx, or direct invasion from sinuses
  
−
* May be secondary to otitis media or sinusitis
  
−
* CSF leaks and other defects predispose to infection
  
−
* Diagnostic yield in CSF decrease significantly 4 hours after administration of antibiotics
  
   
  +
*Acute onset of cough (92%), fatigue (63%), shortness of breath (47%), and dyspnea (23%) with documented or subjective fever (92%), chills (77%), sweats, purulent sputum, and pleuritic chest pain (79%)
  +
  +
===Meningitis===
  +
  +
*Most common cause of [[bacterial meningitis]] in adults
  +
*Acquired by hematogenous spread from nasopharynx, or direct invasion from sinuses
  +
*May be secondary to otitis media or sinusitis
  +
*CSF leaks and other defects predispose to infection
  +
*Diagnostic yield in CSF decrease significantly 4 hours after administration of antibiotics
  +
  +
==Management==
  +
{| class="wikitable"
  +
! rowspan="2" |Scenario
  +
! colspan="3" |Penicillin (μg/mL)
  +
! colspan="3" |Ceftriaxone (μg/mL)
  +
|-
  +
!S
  +
!I
  +
!R
  +
!S
  +
!I
  +
!R
  +
|-
  +
|Non-meningitic oral
  +
|≤0.06
  +
|0.12-1
  +
|≥2
  +
|
  +
|
  +
|
  +
|-
  +
|Non-meningitic parenteral
  +
|≤2
  +
|4
  +
|≥8
  +
|≤1
  +
|2
  +
|≥4
  +
|-
  +
|Meningitic parenteral
  +
|≤0.06
  +
|
  +
|≥0.12
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|≤0.5
  +
|1
  +
|≥2
  +
|}
  +
  +
==Prevention==
  +
  +
===Vaccination===
  +
  +
*Essentially two forms of vaccine available in Canada
  +
**Pneu-C-13: 13-valent pneumococcal conjugate vaccine (Prevnar-13)
  +
***More immunogenic, but fewer serotypes
  +
***Routine childhood immunization, also used for immunocompromised adults
  +
***Includes serotypes: 4, 9V, 6B, 14, 18C, 19F, 23F, 1, 5, 7F, 3, 6A, and 19A
  +
***Given at least 1 year after Pneu-P-23
  +
**Pneu-P-23: 23-valent pneumococcal polysaccharide vaccine (Pneumovax)
  +
***Less immunogenic, but more serotypes
  +
***Routine immunization in elderly
  +
***Includes above serotypes (except 6A), plus 2, 8, 9N, 10A, 11A, 12F, 15B, 17F, 20, 22F, and 33F
  +
***Given at least 8 weeks after Pneu-C-13 and at least 5 years after most recent Pneu-P-23 (except HSCT patients)
  +
***Booster given at 5 years if they are at risk of poor antibody response
  +
  +
{| class="wikitable"
  +
!Age
  +
!Status
  +
!Vaccine
  +
|-
  +
|<18
  +
|routine
  +
|2 to 4 doses PC-13, depending on age
  +
|-
  +
| rowspan="3" |18-64
  +
|healthy
  +
|no routine vaccination
  +
|-
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|[[Tobacco use disorder|smoking]], [[Alcohol use disorder|alcohol]], injection drug use, homeless, long-term care facility
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|1 dose PP-23
  +
|-
  +
|high risk for invasive disease
  +
|1 dose PP-23 ± booster at 5 years
  +
|-
  +
| rowspan="2" |≥18
  +
|immunocompromised
  +
|1 dose PC-13, followed in 8 weeks by 1 dose PP-23 with booster at 5 years
  +
|-
  +
|HSCT recipient
  +
|3 doses PC-13 q4wk starting 3-9 months post-transplant, followed 6-12 months later by 1 dose PP-23 ± booster at 1 year
  +
|-
  +
|≥65
  +
|healthy, regardless of prior vaccination
  +
|1 dose PP-23
  +
|}
  +
  +
*'''Conditions with high risk''' for invasive disease include (highest risk are bolded): [[CSF leak]], chronic neurologic conditions that impair clearance of oral secretions, cochlear implants, chronic heart disease, [[diabetes mellitus]], '''[[chronic kidney disease]]''', '''[[chronic liver disease]]''' including [[cirrhosis]], and chronic lung disease including [[asthma]] requiring medical care within past 12 months
  +
*'''Immunocompromising conditions''': [[hyposplenia]] (including [[sickle cell disease]], [[asplenia]], or splenic dysfunction), [[primary immunodeficiency]], therapeutic immune suppression (including [[corticosteroids]], [[chemotherapy]], [[radiation therapy]], and transplantation), [[HIV]], [[HSCT]], [[malignancy]], [[nephrotic syndrome]], [[solid organ transplantation]]
  +
  +
=== Post-Exposure Management ===
  +
  +
* Per Public Health Ontario, no specific management is required for close contacts
 
{{DISPLAYTITLE:''Streptococcus pneumoniae''}}
  
{{DISPLAYTITLE:''Streptococcus pneumoniae''}}
 
[[Category:Gram-positive cocci]]
  
[[Category:Gram-positive cocci]]

Latest revision as of 11:15, 17 September 2023

Background

Microbiology

  • Gram-positive, lancet-shaped diplococcus
  • 90+ serotypes, based on capsular polysaccharide that is bound to peptidoglycan
  • Lab identification is based on catalase negative, α hemolysis of blood agar (from pneumolysin), optochin susceptibility, and bile salt solubility
  • Via transformation, bacteria can exchange genetic material with each other

Antibiotic Resistance

  • Penicillin resistance
    • S. pneumoniae has 6 PBPs: 1A, 1B, 2A, 2B, 2X, and 3
    • Resistance in any of the PBPs can increase the MIC
    • Mutations in PBP 2B are associated with low-level resistance
    • Mutations in PBP 2X are associated with high-level resistance
  • Macrolide resistance
    • ermB encodes an enzyme that methylates the 23S subunit, blocking macrolides and giving very high MIC ≥64
    • mefA encodes an efflux pump that gives a relatively lower MIC ≤16

Epidemiology

  • Present worldwide
  • Major cause of morbidity and mortality in children
    • Leading cause of under-5 mortality worldwide

Pathophysiology

  • Acquired by coughing and sneezing
  • Asymptomatic carriage or colonization in the nasopharynx
  • Invasion through epithelial cells into the bloodstream, using the PAF and pIg receptors
  • Capsule and various proteins help it to evade immune system

Clinical Manifestations

Asymptomatic Carriage

  • 4-10% in the general adult population, usually lasting several weeks
  • Highest in children, up to 30-60% depending on the situation, lasting up to 6 months

Otitis Media

Sinusitis

Bacteremia

Pneumonia

  • Acute onset of cough (92%), fatigue (63%), shortness of breath (47%), and dyspnea (23%) with documented or subjective fever (92%), chills (77%), sweats, purulent sputum, and pleuritic chest pain (79%)

Meningitis

  • Most common cause of bacterial meningitis in adults
  • Acquired by hematogenous spread from nasopharynx, or direct invasion from sinuses
  • May be secondary to otitis media or sinusitis
  • CSF leaks and other defects predispose to infection
  • Diagnostic yield in CSF decrease significantly 4 hours after administration of antibiotics

Management

Scenario Penicillin (μg/mL) Ceftriaxone (μg/mL)
S I R S I R
Non-meningitic oral ≤0.06 0.12-1 ≥2
Non-meningitic parenteral ≤2 4 ≥8 ≤1 2 ≥4
Meningitic parenteral ≤0.06 ≥0.12 ≤0.5 1 ≥2

Prevention

Vaccination

  • Essentially two forms of vaccine available in Canada
    • Pneu-C-13: 13-valent pneumococcal conjugate vaccine (Prevnar-13)
      • More immunogenic, but fewer serotypes
      • Routine childhood immunization, also used for immunocompromised adults
      • Includes serotypes: 4, 9V, 6B, 14, 18C, 19F, 23F, 1, 5, 7F, 3, 6A, and 19A
      • Given at least 1 year after Pneu-P-23
    • Pneu-P-23: 23-valent pneumococcal polysaccharide vaccine (Pneumovax)
      • Less immunogenic, but more serotypes
      • Routine immunization in elderly
      • Includes above serotypes (except 6A), plus 2, 8, 9N, 10A, 11A, 12F, 15B, 17F, 20, 22F, and 33F
      • Given at least 8 weeks after Pneu-C-13 and at least 5 years after most recent Pneu-P-23 (except HSCT patients)
      • Booster given at 5 years if they are at risk of poor antibody response
Age Status Vaccine
<18 routine 2 to 4 doses PC-13, depending on age
18-64 healthy no routine vaccination
smoking, alcohol, injection drug use, homeless, long-term care facility 1 dose PP-23
high risk for invasive disease 1 dose PP-23 ± booster at 5 years
≥18 immunocompromised 1 dose PC-13, followed in 8 weeks by 1 dose PP-23 with booster at 5 years
HSCT recipient 3 doses PC-13 q4wk starting 3-9 months post-transplant, followed 6-12 months later by 1 dose PP-23 ± booster at 1 year
≥65 healthy, regardless of prior vaccination 1 dose PP-23

Post-Exposure Management

  • Per Public Health Ontario, no specific management is required for close contacts
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