MMSC 428 Final
(2026 Expert-Verified Final
Exam Q & A )
Latest Updated Version
(A+ Guaranteed )
,Staphylococcus aureus -gram positive cocci in clusters
-facultative aerobe (prefers O2)
-halotonic
-ferment mannitol (yellow on MSA plate)
-catalase +
-coagulase +
-clumping factor +
-medium sized b-hemolytic white colonies
-serological tests for TSST-1 and DNA probes are the best diagnosis methods
-most clinically significant staphylococcus
-important cause of nosocomial infection
staphylococcus aureus virulence mechanisms -protein A: virulent cell wall protein that binds to IgG antibodies and prevents them
from being active
-hemolysins: produce B-hemolysis of RBCs
-exfoliatin: causes epidermal layer of skin to peel off
-pyrogenic toxin: causes fever
-toxic shock syndrome toxin 1 (TSST-1): super antigen over stimulates the T cells
and produces cytokine storm
-panton valentine leukocidin (PVL): lyses WBCs, platelets and RBCs
-staphycoagulase: activates fibrin to cause clotting and prevent WBCs from
reaching the bacteria
-hyaluronidase: breaks down hyaluronic acid in tissue to spread bacteria
-lipases & proteases: destroy host tissues and spread bacteria
staphylococcus aureus clinical manifestations -furuncle: large raised suppurative dome shaped boil due to infection of oil gland or
hail follicle
-carbuncle: a furuncle that progresses and infects a deeper level of the skin,
infection causes systemic symptoms of fever and chills
-impetigo: bullous (>5 mm) domed fluid filled pustules surrounded by zone of
erythema, mainly seen in children
-cellulitis: inflammatory infection of connective tissue
-staphylococcal scalded skin syndrome (SSS): release of exfoliatin exotoxin causes
exfoliative dermatitis with red peeling skin that resembles a burn, mainly in children
and newborns
-toxic shock syndrome (TSS): release of TSST-1 and enterotoxin B cause systemic
symptoms including fever, liver and kidney damage, vomiting, diarrhea, muscle
aches and rash, menstrual and non-menstrual forms
-endocarditis
-intoxication food poisoning: food is contaminated with enterotoxins (no actual
bacteria) and causes vomiting and diarrhea
-nosocomial infections: wound infections, osteomyelitis, biofilm on body implants
-childhood infections: SIDS, head and neck infection
staphylococcus aureus drug resistance -penicillin resistant due to acquiring beta-lactamase genes
-MRSA: methicillin resistant staphylococcus aureus
-VISA: vancomycin intermediate staphylococcus aureus
-VRSA: vancomycin resistance staphylococcus aureus
staphylococcus epidermidis -gram positive cocci in clusters
-nonmotile
-facultative anaerobe (prefer O2)
-smooth, round, non-hemolytic white colonies on BSA
-staphycoagulase - (indicated by the fact that it is nonhemolytic)
-clumping factor -
-PYR -
-ODC d+
-is part of the normal biota, only causes opportunistic infections
-hospital acquired infections: biofilms, septicemia, osteomyelitis, catheter
associated UTI
2026
, staphylococcus lugdunensis -gram positive cocci in clusters
-staphycoagulase -
-clumping factor d+
-PYR +
-ODC + (very strong and fast)
-mannitol -
-nonhemolytic
-oxacillin resistant (mecA gene)
-highly virulent
-equally clinically significant as Staphylococcus aureus, just isolated less frequently
-community and hospital acquired infections: skin abscess, meningitis, septicemia,
septic shock, UTI
-endocarditis: very aggressive and fatal
staphylococci characteristics -gram positive cocci that grow in clusters
-catalase + (good to differentiate from streptococcus)
-non-motile, lack flagella
-facultative anaerobes (prefer O2)
-lysostaphin sensitive
-glucose fermentation +
-modified oxidase test -
-bacitracin resistant
-produce a sticky glycocolyx that allow them to establish a biofilm
-important causes of hospital acquired infections
micrococcus -gram positive cocci in pairs, tetrads or clumps
-related to staphylococci, but less clinically significant
-lysostaphin resistant (would only be able to lyse staphylococcus cells)
-glucose fermentation -
-modified oxidase (cytochrome C oxidase) +
-bacitracin sensitive
streptococcus pyogenes (group A strep) -gram positive cocci in chains
-lancefield group A cell wall antigens
-aerotolerant anaerobe (fermentation only)
-modified oxidase test -
-catalase -
-PYR + (the only B-hemolytic strep that is)
-B-hemolytic
-bacitracin sensitive
-fastidious
-requires blood to be cultured
-small, transparent, dry colonies
-the most virulent streptococci
-usually detected using antigen detection or serology
streptococcus pyogenes (group A strep) virulence -streptolysin O: hemolysin that is active in anaerobic conditions, produces B-
mechanisms hemolysis
-streptolysin S: hemolysin that is active in aerobic conditions, produces B-hemolysis
-M protein: virulent protein that aids attachment to host cells and evades WBC
phagocytosis
-hyaluronic acid capsule: weakly immunogenic, body does not fight it off
-pili: adhesion
-streptokinase: anti-clotting factor that breaks down clots so bacteria can spread
-hyaluronidase: breaks down skin and allows more bacterial spreading
-streptodornoase: breaks down extracellular DNA from lysed host cells and uses it
to make its own nucleic acids
2026
(2026 Expert-Verified Final
Exam Q & A )
Latest Updated Version
(A+ Guaranteed )
,Staphylococcus aureus -gram positive cocci in clusters
-facultative aerobe (prefers O2)
-halotonic
-ferment mannitol (yellow on MSA plate)
-catalase +
-coagulase +
-clumping factor +
-medium sized b-hemolytic white colonies
-serological tests for TSST-1 and DNA probes are the best diagnosis methods
-most clinically significant staphylococcus
-important cause of nosocomial infection
staphylococcus aureus virulence mechanisms -protein A: virulent cell wall protein that binds to IgG antibodies and prevents them
from being active
-hemolysins: produce B-hemolysis of RBCs
-exfoliatin: causes epidermal layer of skin to peel off
-pyrogenic toxin: causes fever
-toxic shock syndrome toxin 1 (TSST-1): super antigen over stimulates the T cells
and produces cytokine storm
-panton valentine leukocidin (PVL): lyses WBCs, platelets and RBCs
-staphycoagulase: activates fibrin to cause clotting and prevent WBCs from
reaching the bacteria
-hyaluronidase: breaks down hyaluronic acid in tissue to spread bacteria
-lipases & proteases: destroy host tissues and spread bacteria
staphylococcus aureus clinical manifestations -furuncle: large raised suppurative dome shaped boil due to infection of oil gland or
hail follicle
-carbuncle: a furuncle that progresses and infects a deeper level of the skin,
infection causes systemic symptoms of fever and chills
-impetigo: bullous (>5 mm) domed fluid filled pustules surrounded by zone of
erythema, mainly seen in children
-cellulitis: inflammatory infection of connective tissue
-staphylococcal scalded skin syndrome (SSS): release of exfoliatin exotoxin causes
exfoliative dermatitis with red peeling skin that resembles a burn, mainly in children
and newborns
-toxic shock syndrome (TSS): release of TSST-1 and enterotoxin B cause systemic
symptoms including fever, liver and kidney damage, vomiting, diarrhea, muscle
aches and rash, menstrual and non-menstrual forms
-endocarditis
-intoxication food poisoning: food is contaminated with enterotoxins (no actual
bacteria) and causes vomiting and diarrhea
-nosocomial infections: wound infections, osteomyelitis, biofilm on body implants
-childhood infections: SIDS, head and neck infection
staphylococcus aureus drug resistance -penicillin resistant due to acquiring beta-lactamase genes
-MRSA: methicillin resistant staphylococcus aureus
-VISA: vancomycin intermediate staphylococcus aureus
-VRSA: vancomycin resistance staphylococcus aureus
staphylococcus epidermidis -gram positive cocci in clusters
-nonmotile
-facultative anaerobe (prefer O2)
-smooth, round, non-hemolytic white colonies on BSA
-staphycoagulase - (indicated by the fact that it is nonhemolytic)
-clumping factor -
-PYR -
-ODC d+
-is part of the normal biota, only causes opportunistic infections
-hospital acquired infections: biofilms, septicemia, osteomyelitis, catheter
associated UTI
2026
, staphylococcus lugdunensis -gram positive cocci in clusters
-staphycoagulase -
-clumping factor d+
-PYR +
-ODC + (very strong and fast)
-mannitol -
-nonhemolytic
-oxacillin resistant (mecA gene)
-highly virulent
-equally clinically significant as Staphylococcus aureus, just isolated less frequently
-community and hospital acquired infections: skin abscess, meningitis, septicemia,
septic shock, UTI
-endocarditis: very aggressive and fatal
staphylococci characteristics -gram positive cocci that grow in clusters
-catalase + (good to differentiate from streptococcus)
-non-motile, lack flagella
-facultative anaerobes (prefer O2)
-lysostaphin sensitive
-glucose fermentation +
-modified oxidase test -
-bacitracin resistant
-produce a sticky glycocolyx that allow them to establish a biofilm
-important causes of hospital acquired infections
micrococcus -gram positive cocci in pairs, tetrads or clumps
-related to staphylococci, but less clinically significant
-lysostaphin resistant (would only be able to lyse staphylococcus cells)
-glucose fermentation -
-modified oxidase (cytochrome C oxidase) +
-bacitracin sensitive
streptococcus pyogenes (group A strep) -gram positive cocci in chains
-lancefield group A cell wall antigens
-aerotolerant anaerobe (fermentation only)
-modified oxidase test -
-catalase -
-PYR + (the only B-hemolytic strep that is)
-B-hemolytic
-bacitracin sensitive
-fastidious
-requires blood to be cultured
-small, transparent, dry colonies
-the most virulent streptococci
-usually detected using antigen detection or serology
streptococcus pyogenes (group A strep) virulence -streptolysin O: hemolysin that is active in anaerobic conditions, produces B-
mechanisms hemolysis
-streptolysin S: hemolysin that is active in aerobic conditions, produces B-hemolysis
-M protein: virulent protein that aids attachment to host cells and evades WBC
phagocytosis
-hyaluronic acid capsule: weakly immunogenic, body does not fight it off
-pili: adhesion
-streptokinase: anti-clotting factor that breaks down clots so bacteria can spread
-hyaluronidase: breaks down skin and allows more bacterial spreading
-streptodornoase: breaks down extracellular DNA from lysed host cells and uses it
to make its own nucleic acids
2026
