Aerobic Cocci Flashcards
Pathogenicity of Strep agalactiae
Group B specific antigen, infections in newborns and women who become ill after childbirth-endometritis and wound infections.
Pathogenicity of Strep pyogenes
Bacterial pharyngitis, pyoderma infections, rheumatic fever invasive Streptococcal infections
Pathogenicity of Strep pneumoniae
CA - Pneumonia, sinusitis, otitis media, bacteremia and meningitis
Pathogenicity of Strep viridians
subacute bacterial endocarditis, immunocompromised meningitis, abscesses, osteomyelitis
Pathogenicity of Enterococcus
UTI’s, wound infections, interabdominal abscesses
Pathogenicity of Pedicoccus
Isolated from saliva, stool, urine, and wounds, rarely causes disease but septicemia and bacteremia have been reported
Pathogenicity of Strep milleri (anginosus)
Abscesses and other pyogenic infections
Pathogenicity of Staph aureus
Skin and wound infections, food poisoning, scalded skin syndrome, toxic shock syndrome
Pathogenicity of Staph epidermidis
Predominantly hospital-acquired, with catheterization prosthetic heart valve implantation
Pathogenicity of Staph saprophyticus
UTI’s in young sexually active females
Pathogenicity of Micrococcus
Rarely causes infections
Pathogenicity of Stomatococcus
Opportunistic pathogen isolated most often from drug abuse
Colony and microscopic morphology of staphylococcus
White, smooth colonies, may or may not produce pigment or hemolysis, GPC in clusters or tetrads
Colony and microscopic morphology of beta Strep groups A & B
Group A - large zone of beta hemolysis, tiny PP colonies, gram pos. cocci in chains. Group B - narrow zone of beta hemolysis, small white colonies, gram pos. cocci in chains
Colony and microscopic morphology of Enterococcus
Small white colonies with disappearing borders, can show any hemolysis, gram pos cocci in chains
List tests to distinguish between Staphylococcus aureus and other Staphylococcus species
Staph aureus has a positive coagulase test and latex
What test distinguishes Staphylococci from Streptococci
Catalase
Discuss the types of hemolysis and what is happening to the RBCs
Beta - complete clearing of RBCs (clear, yellow)
Alpha - partial lysis of RBCs (Green)
Gamma - No change in background
Does beta hemolysis always indicate the presence of Streptococci
no
3 ways to identify enterococcus
Automated systems, PYR, Bile esculin and 6.5% NaCl
Describe the leucine aminopeptidase test (LAP) and list the organisms it differentiates.
Leucine aminopeptiase is a peptidase that hydrolyzes peptide bonds adjacent to a free amino group. Because LAP reacts most quickly with Leucine. The addition of DMACA causes a red color to develop in pos. tests.
- LAP differentiates Aerococcus and Leuconostoc from other GPC.
- LAP positive for strept, entero, and pediococcus spp.
Significance of vancomycin resistant Enterococcus, including how the genetic material is acquired
Widespread use of vancomycin has led to VRE. There are two choices for VRE: synercid and linezolid. Proteins encoded by vanA and vanB genes give its resistance. Enterococcus spp containing the Van A phenotype are highly resistant. Modify peptidoglycan termini, N-acyl-D-Ala-D-Ala, involved in cross-linking to N-Acyl-D-Ala-D-Lactate.
Compare and contrast hospital aquired MRSA and community aquired MRSA
Hospital: HA-MRSA is the name for infections acquired while in the hospital recently, long term care, dialysis, or indwelling devices
Community: CA-MRSA is the name for infections amongst people who lack traditional healthcare associated risk factors. Outbreaks have been among athletes, correctional facility inmates, military recruits in barracks, pediatric patients and tattoo recipients.
Virulence factors for Streptococcus
- M protein
- Enzymes (Streptolysin O and S)
- DNAase A-D
- Streptokinase A and B
- Pyrogenic toxins A-C
- Capsule