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37 terms

6141 Microbiology Lecture 2

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Streptococci: gram negative or gram positive?
Gram positive
Streptococci: coagulase negative or positive?
Coagulase negative
What type of Strep is in group A?
Strep. pyogenes (over 130 different strains (M-protein types))
What type of Strep is in group B?
Strep agalactiae
What type of Strep is in group D?
Strep bovis
What are some examples of pyogenic disease caused by Strep. pyogenes?
pharyngitis, impetigo, erisypelas, cellulitis, pneumonia
What are some examples of immune-related disease caused by Strep pyogenes?
Rheumatic fever, glomerulonephritis
What are some toxinoses caused by Strep pyogenes?
Scarlet fever, streptococcal toxic shock syndrome, necrotizing fasciitis
What is the significance of M proteins when discussing Streptococcus?
M proteins help determine the type of Group A Strep present. Different types cause different diseases.
What causes Erysipelas?
Bacterial enzymes (inflammation related and degradative): hyaluronidase, nucleases, hemolysins
Describe Strep pyogenes related cellulitis.
Infection of deeper tissue, erysipelas is more superficial.
What are the symptoms of rheumatic fever?
fever, rash, carditis (heart valve damage afterwards), and arthritis
What causes rheumatic fever?
Strep pyogenes: anti-M protein antibodies cross-react with heart and joint tissue antigens
What causes glomerulonephritis?
Antigen-antibody complexes accumulate on the glomerular basement membrane
What are the symptoms of glomerulonephritis?
hypertension, edema of the face and ankles, bloody urine
What causes Scarlet fever?
Streptococcus pyogenes: erythrogenic toxin, a pyogenic exotoxin.
What are the symptoms of scarlet fever?
diffuse red sunburn-like rash on the neck, trunk, and extremities
History of Strep pyogenes - 18th and 19th centuries
Streptococcal fasciitis in wounded soldiers, puerperal fever (women), blood poisoning
History of Strep pyogenes - late 19th to early 20th centuries
Scarlet and rheumatic fever
History of Strep pyogenes - 1940s to present
Scarlet and rheumatic fever virtually disappear
History of Strep pyogenes - Late 20th century
Scarlet fever outbreaks, TSS, fasciitis, pneumonia, nosocomial wound infections, invasive systemic infections
What is another name for necrotizing fasciitis?
Flesh-eating bacteria
Name several pathologies caused by Strep pneumoniae (pneumococcus)
Meningitis, Acute pneumonia, Otitis media
What causes meningitis?
Strep pneumoniae adheres to endothelial cells of the meninges (the membranes surrounding the brain and the spinal cord
What are some predisposing factors of acute pneumonia?
Repressed cough reflex (drugs and alcohol), respiratory tract infection (influenza virus) or damage (smoking), abnormal circulatory dynamics (heart/lungs), chronic diseases (sickle-cell anemia, nephrosis), head injuries (for meningitis)
In individuals less than 1 mo. of age, which organisms are most likely to cause infection?
Streptococcus group B (69.5%) and Listeria monocytogenes (21.8%)
In individuals 1-23 mo. of age, which organisms are most likely to cause infection?
Streptococcus pneumoniae (45.2%) and Neisseria meningitidis (30.8%)
In individuals 2-29 years, which organisms are most likely to cause infection?
Neisseria meningitidis (59.8%) and Streptococcus pneumoniae (27.2%)
In individuals 30-50 years, which organisms are most likely to cause infection?
Streptococcus pneumoniae (60.6%) and Neisseria menigitidis (18.2%)
In individuals 60+ years of age, which organisms are most likely to cause infection?
Streptococcus pneumoniae (68.6%) and Listeria monocytogenes (21.7%)
What is one of Strep penumoniae's virulence factors?
The capsule: inhibits lysis by phagocytes, over 85 different capsular antigen types
What is the most common cause of the most common childhood infection?
The most common cause: Strep pneumoniae
The most common childhood infeciton: Otitis media
What infections are caused by Strep agalactiae?
meningitis, pneumonia, and bacteremia in neonates
What infections are caused by Strep bovis (Group D)?
nosocomial UTIs, and endocarditis
What infections are caused by Strep mutans (Viridans group)?
causes dental caries, endocarditis, and bacteremia; enters blood stream during dental procedures
What are two species of Enterococcal infections?
Enterococcus faecalis and enterococcus faecium
What are some characteristics of enterococcal infections? (Where organism resides, pathogenesis...)
Reside in colon, nosocomial (second only to Staph aureus), UTIs, bacteremia, wound infections, endocarditis