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14 Cards in this Set

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Staphylococcusaureus

-Most pathogenic of thestaphylococci


-Cause superficial skin infections, deep tissue infections, food poisoning, toxic shock,


-Normally found in nares, axilla, upper respiratory tract, skin surface, and groin


-Gram Positive Cocci


-Catalase Positive


-Growth + fermentation in MSA plate

Staphylococcusepidermidis

- Normal microbiota: skin and mucousmembranes; distributed widely over body surface


- Can cause infections in immunocompromisedpatients


- Associatedwith indwelling prosthetic devices—intravascular catheters, cardiac valves,joints, cerebral shunts; bacteremia; UTIs; wounds


-Catalase Postive


-Gram Positive Cocci in Clusters


-Growth + No fermentation in MSA plate

Staphylococcussaprophyticus

-Second most common cause ofuncomplicated UTIs in women


- Cause urinary tract infections: –Sexuallyactive, young females–Prostatitisin men–Infectionsin sites outside of urinary tract are uncommon


-Normal microbiota: skin and mucosaof the urogenital tract


-Gram Positive Cocci in Clusters


-Catalase Positive


-Growth + no fermentation in MSA plate

Catalase Test

2H2O ------> 2H2O +O2


(Hydrogen Peroxide + Catalase ---> 2 Water Molecules + 1 Oxygen molecules)

Bacteremia

Presence of bacteria in the blood stream

Septicemia

(sepsis) is a systemic bacteremia withclinical signs and symptoms (fever, chills, hypothermia, vomiting,hyperventilation and septic shock).

Risk Factors for Bacterial Sepsis

•Hospitalization•Recent surgery•Hemodialysis•IV and immune therapy•IV drug abuse

Streptococcuspyogenes

- Causes Group A streptococciinfections–Most common cause of pharyngitis


- Produce and secrete toxins and hemolysinsthat contribute to tissue invasion and destruction


- NEVERnormal microbiota in any part of body—always a pathogen; presence in specimensis always considered clinically significant


- Cause infections of the upperrespiratory tract:–Pharyngitis, tonsillitis, otitis media –Can be invasive and infect soft tissue,blood, bone, sterile body sides, sterile body fluids, and wounds –Causes rheumatic fever and acuteglomerulonephritis


-Catalase Negative


-Gram Positive Cocci in Pairs and Chains


-Beta Hemolysis on BAP



Streptococcusagalactiae

-Causes Group B streptococciinfections–Significantneonatal infection


- Norma microbiota: female genitaltract, lower GI tact, may colonize upper respiratory tract


- Infections most commonly involveneonates and infants–Bacteriapassed from mother to child during birth—can cause multisystem problemsincluding sepsis and meningitis–Infectionsin adults include postpartum UTIs–Immunocompromisedpatients are at risk for infection


-Catalase Negative


-Gram Positive Cocci in Pairs and Chains


-Gamma or Beta Hemolysis on BAP

Streptococcuspneumoniae

-Class C


-#1 cause of community acquiredbacterial pneumonia


-Normal microbiota: upperrespiratory tract -Causes infections of the upperrespiratory tract–Pneumonia,sinusitis, and otitis media–Canbecome invasive and cause bacteremia and meningitis


-Catalase Negative


-Gram Positive Cocci in Pairs and Chains


-Alpha Hemolysis on BAP

Enterococcusfaecalis

-Causes group D streptococciinfections –Importantnosocomial infection, especially vancomycin resistant strains (VRE)


-Normal microbiota: gastrointestinaltract


-Most infections are nosocomial(originates in hosptials) –IncludeUTIs, bacteremia, endocarditis, and wound infections


-Catalase Negative


-Gram Positive Cocci in Chains and Pairs


-Gamma Hemolysis



Alpha Hemolysis

Causes partial lysis of RBCs andbreakdown of hemoglobin which leads to a green color change in the agar.

Beta Hemolysis

Causes complete lysis of RBCs andbreakdown of hemoglobin which leads to a colorless clearing in the agar.

Gamma Hemolysis

An organism that does not causehemolysis.