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#4 Bacterial infection of the respiratory system
n/a
33
Microbiology
Graduate
08/17/2012

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Cards

Term
What gram positive cocci is seen in bacterial infection of the respiratory system?
Definition
Staphylococcus, streptococcus, enterococcus
Term
What gram negative cocci is seen in bacterial infection of the respiratory system?
Definition
Neisseriaceae (N. Gonorrhoeae and N. Meningitidis), moraxella, acinetobacter
Term
What gram positive bacteria are spore formers?
Definition
Bacillus and clostridium
Term
What gram negative bacteria are anaerobes?
Definition
Actinomyces, bacteroides, and clostridium
Term
What are the three classifications of streptococci?
Definition
Pyogenic streptococci, penumococci, and viridans
Term
What is characteristic of pyogenic streptococci?
Definition
Contains lancefield antigen (cell wall carbohydrate), may be alpha or beta hemolytic
Term
What is characteristic of viridans (streptococci)?
Definition
Non hemolytic, normal flora of oral cavity
Term
What is characteristic of pneumococci (streptococci)
Definition
Only one member, S. pneumoniae
Term
What is the most common cause for seeking medical care in the US?
Definition
Strep throat due to streptococcal pharyngitis caused by the bacteria Streptococcus pyogenes
Term
What is the morphology of Streptococcus pyogenes?
Definition
Gram positive oval cells growing in chains, non acid-fast, no spore, non-motile, may or may not have capsules
Term
How is Streptococcus pyogenes cultured?
Definition
Blood agar, cultures as small colonies with a possible surrounding zone of hemolysis, glucose fermentation yields lactic acid
Term
What is the different hemolytic zones that may surround Streptococcus pyogenes cultures?
Definition
Beta-hemolysis = clear zone surrounding the colony (complete hemolysis), alpha-hemolysis = hazy zone with green discoloration (incomplete hemolysis)
Term
What are the symptoms of strep throat?
Definition
Soreness of throat, difficult swallowing, fever, malaise, headache, red throat, which patches of pus with hemorrhagic spots or yellowish white exudates, enlarged/tender cervical lymph nodes, abdominal pain (not always)
Term
Virulence of Streptococcus pyogenes is mediated by what?
Definition
Cell wall components
Term
What is a positive sign of a rapid strep test?
Definition
Visible clumps produced by antigen and antibody interaction, negative sign has a smooth, milky reaction
Term
What is the only beta-hemolytic pathogen that is bacitracin sensitive?
Definition
Gr. A streptococcus
Term
How is strep throat treated?
Definition
Penicillin is the first choice, erythromycin and first generation of cephalosporin (cephalexin) may be given to penicillin sensitive patients
Term
What kind of complications can arise from streptococcal pharyngitis?
Definition
Scarlet fever, strawberry tongue
Term
What causes scarlet fever?
Definition
Infection with Streptococcus pyogenes that is itself infected with a bacteriophage, arythrogenic toxics enter blood and cause rashes
Term
What is rheumatic fever?
Definition
Complication of streptococcal pharyngitis, antibody generated against streptococcal antigens cross-reacts with antigenic apitopes on cardiac cells, damages valves cause sub-acute bacterial endocarditis
Term
What are the symptoms of rheumatic fever?
Definition
Fever, joint pain, chest pain, nodules under the skin, rash, chorea
Term
What must be present for a diagnosis of rheumatic fever?
Definition
Must have last 2 major criteria: carditis, arthritis, chorea, subcutaneous nodules, arythema marginatum or one major and two minor criteria: fever, joint pain, electrical changes in the heart, evidence of certain proteins in the blood
Term
How is rheumatic fever treated?
Definition
Ten day course of penicillin or single injection of penicillin-G, aspirin for pain and inflammation, steroids are sometimes used for carditis, diazepam or haloperidol fo rChorea
Term
What provides immunity to rheumatic fever?
Definition
Type-specific IgA prevents adhesion and IgG against M-protein protects against invasion, though there are too many strains of GAS to prevent repetitive infections
Term
What renal complications can arise from Streptococcus pyogenes?
Definition
Acute glomerulonephritis
Term
What is the causative agent of Pneumococcal pneumonia?
Definition
Streptococcus pneumoniae - a gram positive diplococcus, has very thick capsule (major virulent factor)
Term
Why is Streptococcus pneumoniae referred to as diplococci?
Definition
Resides in pairs
Term
Where is Streptococcus pneumoniae found?
Definition
Normal flora in the upper respiratory tract that normally does not reach lower respiratory tract, compromised immune status renders individual susceptible
Term
What are the symptoms of pneumonia?
Definition
Runny nose, chest congestion, cough, fever with chills, chest pain, purulen sputum, shallow/rapid breathing, low oxygenation
Term
Why do Streptococcus pneumoniae avoid phagocytosis when infecting lung alveoli?
Definition
Thick capsule
Term
Streptococcus pneumoniae entering the blood stream causes what?
Definition
Septicemia
Term
What is the #1 cause of meningitis in adults?
Definition
Pneumonia infected meninges
Term
How is S. pneumoniae diagnosed?
Definition
Identification of gram positive diplococci in smears in blood agar, distinguished from S. viridans by susceptibility to Optochin or by bile solubility
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