Micro Block II: Lecture ___ Streptococcus pneumonia

What bacteria perform alpha hemolysis?

*1) Streptococcus pneumoniae 2) Viridans group* a) subacute endocarditis-*S. sanguis, S. mitis, S. mutans* b) abscess formation- *S. anginosus group--> S. intermedius*

Viridans group

*Normal flora in the oral cavity* *Enter the bloodstream after dental manipulations or oral trauma*

Streptococcus pneumonia is often referred to by what other name?

*Pneumococcus*

Streptococcus pneumoniae microscopic morphology

*lancet-shaped diplococci*

Streptococcus pneumoniae colonization

*normal flora in upper respiratory tract (20-70%)* -especially high in children and adults with young children

Streptococcus pneumoniae epidemiology

*susceptible populations* 1. superficial URT infection (e.g. otitis media) - *infants and children* 2. invasive infections (pneumonia, meningitis) - *very young, elderly*, anyone with an *underlying disease* such as chronic alcoholism, stroke, asplenia, or prior respiratory disease

*PCV-13 (Prevnar 13) - new in 2010*

- addition of *six new purified polysaccharides* to cover capsule serotypes that were not part of the PCV 7 - should be used in place of the PCV 7 for children

PPV (PNEUMOVAX 23) (best vaccine for adults)

-purified polysaccharide from the *23 most common isolates* (90%) -works well in adults but *no response in children less than 2 years of age* -*still used in adults because of broad coverage* - given *every 5 years*

Streptococcus pneumoniae transmission

-spread of normal flora from person to person -disease caused by *spread of normal flora from naso/oropharynx to adjacent tissue or aspiration into the lungs*

Prevention against S. Pneumoniae infection

1) *Antibodies against the CAPSULE* is the primary defense against pneumococcal disease 2) *Vaccines*- two different vaccines still in use for different populations

What are the two types of vaccines used to prevent S. Pneumoniae infection?

1) *PPV (PNEUMOVAX 23)- the best vaccine for *ADULTS* 2) *Conjugate Vaccine*- for children

Streptococcus pneumoniae Exotoxins and Enzymes

1) *Pneumolyisn*- oxygen-labilie, cross-reacts with streptolysin O- kills phagocytes 2) IgA protease

What are the diseases caused by streptococcus pneumoniae?

1) *Pneumonia* complications: *a) pleural effusion with empyema (pus) b) bacteremia with meningitis* Upper respiratory tract infections: 2) *Otitis media* 3) *Sinusitis, Conjunctivitis*

Treatment of S. Pneumoniae *Traditional (sensitive) Strains*

1. *Oral Penicillin* for documented mild cases 2. *Penicillin G* (im or iv) for pneumonia, meningitis, endocarditis 3. *Otitis media - amoxicillin* 4.*Conjunctivitis - fluoroquinolones* 5. *Sinusiti*s - same as for otitis media--> fluoroquinolones

Upper Respiratory Tract Infections caused by streptococcus pneumonia (primarily in infants and children)

1. *Otitis media - S. pneumoniae is the most common cause of otitis media!!!* 2. Other infections - *sinusitis, conjunctivitis*

Pneumonia

1. *Rapid onset, shaking chills, fever, developing cough with copious "rusty" sputum* 2. X-ray usually shows *heavy consolidation* 3. *Major cause of both nosocomial and community-acquired pneumonia* 4. 500,000 cases/yr in U.S. with more than 50,000 deaths 5. 5% fatality even when treated appropriately *due to the weakened defenses and underlying diseases of most patients*

Treatment of S. Pneumoniae *Penicillin-Resistant Strains*

1. *Vancomycin* 2. Active *fluoroquinolones* 3. Some 3rd generation cephalosporins 4. Telithromycin 5. Linezolid (oxazolidinone) 6. Ceftaroline

Streptococcus pneumoniae cellular antigens

1. Peptidoglycan 2. Teichoic acid 3. Lipoteichoic acid 4. Cell wall proteins 5. *Capsule - major virulence factor, anti-phagocytic* -*polysaccharide polymers, more than 83 different serotypes* -*antibody to the capsule is protective - vaccine target!*

Laboratory Diagnosis of S. pneumoniae

1. Specimen collection 2. *Direct examination (rapid)* RAPID a. *Gram stain* RAPID b. *urine antigen test - commercial kit (1999) - pneumonia (and meningitis)* c. antigen detection in CSF (meningitis) - commercial kits have *poor sensitivity* 3. *Culture - blood agar* (24 hr, not rapid)- observe for *α-hemolysis, mucoid colonies* 4. *Antibiotic sensitivities*- *all isolates must be tested for resistance to penicillin* ; increase in resistant strains

Complications of Pneumonia

1.* Pleural effusion with empyema (pus)* 2. *Bacteremia with meningitis* - spread from the pleura→ lymphatics→ bloodstream→ meninges *most common meningitis in adults* 3. Other bacteremia complications- endocarditis, pericarditis, septic arthritis

Alpha Hemolysis

Incomplete lysis of RBC with *zone of greening* or darkening under and around the colonies; *reaction only seen with streptococci*

S. pneumoniae

Normal flora in URT, common cause of pneumonia, meningitis, otitis media, sinusitis

Conjugate Vaccine (for children)

PCV-7 (Prevnar 7) used from 2000-2010 (not bolded) -purified polysaccharide from the *7 most common serotypes CONJUGATED TO A PROTEIN* - *approved in 2000 for vaccination of all infants at 2, 4, and 6 months, followed by a booster at 12-15 months* - approved for *prevention of bacteremia and meningitis*, but should also reduce pneumonia, otitis media, and other pneumococcal diseases

Break down bacteria in the Viridans group by: a) those that cause *subacute endocarditis, prosthetic joint infections* b) those that cause *abscess formation*

a) 1) *S. sanguis* 2) *S. mitis* 3) *S. mutans* b) 1) *S. angiosus group*- *S. intermedius*