View source for Streptococcus pneumoniae

==Background==
===Microbiology===

*[[Stain::Gram-positive]], lancet-shaped [[Shape::coccus|diplococcus]]
*90+ serotypes, based on capsular polysaccharide that is bound to peptidoglycan
*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
*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
*'''[[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

===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==
{| 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
|≤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
|-
|[[Tobacco use disorder|smoking]], [[Alcohol use disorder|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
|-
| 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''}}
[[Category:Gram-positive cocci]]