Micro: Gram + Bacterial Infections Flashcards
Gram + cocci we will discuss can be grouped into two genera:
Staphylococci & Streptococci
Gram + bacilli we will discuss can b grouped into two categories:
Spore forming & non-spore forming
Name the Gram +, spore forming aerobic/facultative anaerobic genus
Bacillus
Name the Gram +, spore forming obligate anaerobic genus
Clostridia
Name the Gram +, non-spore forming, aerobic or facultative anaerobic genera
Corynebacteria & Listeria
Staphylococci are found in what microscopic morphology?
Grape-like clusters
Streptococci are found in what microscopic morphology?
chains/pairs and chains
List the species of Staph we will discuss.
S. aureus
S. epidermidis
S. saprophyticus
Streptococcus pyogenes are a group A, group B or group D Strep species?
Group A
Streptococcus agalactiae are a group A, group B or Group D Strep species?
Group B
Enterococci & Streptococcus gallolyticus are a group A, group B or Group D Strep species?
Group D
Are S. aureus coagulase + or -?
Positive
Where are S. aureus colonizers?
Skin and mucosa
List the 3 clinical manifestations of S. aureus.
1- Pyogenic infections (boils/abscesses, folliculitis, wound infections, impetigo)
2- Disseminated infections (endocarditis, osteomyelitis, pneumonia (Hosp. acq), bacteremia/sepsis
3- Toxigenic (food poisoning, Toxic Shock syndrome, scalded skin syndrome)
List the 3 broad categories of S. aureus virulence factors.
Surface proteins, enzymes, toxins
T/F: antibiotic resistance is a common and worrisome feature of S. aureus infections.
Truth
What is the cause of most Staph epidermidis infections?
occur in the setting of foreign devices (prosthetic joints/other ortho hardware, central lines, artificial valves, etc.)
What helps Staph epi adhere to foreign objects?
Surface adhesins; BIOFILM (slime) is then produced which encases bacteria shielding them from Abx and immune response
Staphylococcus saprophyticus is normal flora of the female ___________ and ___________.
genital tract; GI tract
Are Staph epi & Staph saprophyticus coagulase - or +?
Negative
What is the 2nd most common cause of UTIs behind E. coli?
Staph saprophyticus
What is the Lancefield antigen?
carbohydrate antigen important for typing, especially for the beta-hemolytic Streps.
Groups A, B, C, D, & G refer to Lancefield antigen
Describe alpha, beta and gamma hemolysis.
A- green blood agar around colonies
B- complete clearing of blood agar (group A & B Strep)
G- No change to BAP
Describe the hemolysis of Strep pyogenes
Beta hemolytic
Describe the Lancefield antigen of Strep pyogenes
Group A
List the virulence factors of Strep pyogenes.
M protein, streptokinase, several different toxins
What pyogenic diseases does S. pyogenes cause?
Pharyngitis, cellulitis, impetigo, necrotizing fasciitis, erysipelas
What toxigenic diseases does S. pyogenes cause?
Scarlet fever, Toxic Shock Syndrome (TSS)
What immune related diseases does S. pyogenes cause?
Rheumatic fever, acute glomerulonephritis
Which group of Strep causes “Strep throat” (pharyngitis)?
Group A
Describe the microscopic morphology of Strep pneumoniae
Lancet shaped diplococci
Describe the hemolysis of Strep. pneumoniae
Alpha hemolytic
List the diseases associated with Strep pneumoniae (more common in young, old and immunocompromised)
Lobar pneumonia
Bacteremia
Meningitis (most common cause)
Otitis media (most common cause)
Name the one virulence factor of Strep pneumoniae
Capsule
Is there a vaccine for Strep pneumoniae?
Yes.
What are the two genera/species of group D Strep?
Enterococcus sp. & Strep gallolyticus
Enterococcus sp of Strep is a part of normal _______ flora.
Colonic flora
Enterococcus is associated with these diseases:
Hospital-acquired UTIs
Blood stream infections
Endocarditis
There is a very strong association between pts with colon cancer and Streptococcus gallolyticus induced ___________.
Endocarditis
There are two forms of anthrax caused by Bacillus anthracis. List them and what causes their symptoms.
Inhalation anthrax and Cutaneous anthrax (most common form)
Both are toxin-mediated (AB toxin)
Which gram positive rod causes food poisoning?
Bacillus cereus. Can be diarrheal or emetic, both toxin-mediated.
List the 4 species of Clostridia.
C. perfringens
C. difficile
C. tetani
C. botulinum
C. perfringens causes what two diseases?
Gas gangrene (alpha toxin) & food poisoning (toxin) 3rd most common food-borne illness
________ (genus & species) is the most common cause of nosocomial diarrhea and most common cause of abx-associated diarrhea.
C. difficile
How does one contract C. dif?
Fecal-oral route
T/F: C. diff’s disease is toxin mediated.
true
Where do you find the spores of C. tetani?
soil
C. tetani’s disease is _______-mediated. Surprise!
Toxin-mediated
Infection with ___________ (genus & species) presents as strong muscle spasms and spastic paralysis (lock-jaw).
C. tetani
What’s the prognosis for a C. tetani infection?
Not good, high mortality. Vaccine is protective against toxin (TdaP, DTap).
C. botulinum causes botulism, a _______-mediated disease.
Toxin-mediated. Almost got you!
Floppy baby syndrome is caused by: (genus/sp)
Clostridium botulinum
What is the 2nd most common cause of botulism?
Food-borne botulism
What are the clinical manifestations of botulism?
hypotonia/difficulty feeding/weakness; flaccid paralysis
Describe the microscopic morphology of Corynbacterium diptheriae. Do it now.
Pleomorphic (size/shape changes in response to env. conditions), club-shaped, arranged in palisades (chinese characters), beaded appearance.
Guess, just GUESS what mediates Corynbacterium diptheriae disease!
AB Toxin you silly goose!
Describe the disease caused by Corynbacterium diptheriae.
Acute pharyngitis with formation of an overlying gray membrane (pseudomembrane) which can cause mechanical obstruction
What is the prophylactic vaccine for C. diptheriae?
DTap/TDaP
Listeria monocytogenes causes these diseases in the extremes of age and in immunocompromised patients?
meningitis, bacteremia
Infection in pregnancy with this bacterium can be devastating- nonspecific flu-like symptoms that can ultimately lead to fetal demise,/miscarriage/infection at birth.
Listeria monocytogenes
If you see chinese language looking bacteria under a microscope, what is it?
Corynbacterium diptheriae
T/F: Group A Strep is ALWAYS susceptible to Penicillins.
True
Impetigo caused by group A strep will have what character and can be found where on the body?
Small, scabbed lesions. Around the mouth.
Impetigo caused by S. aureus will have what character and be found where on the body?
More blister like, more bulbous. Found all over the body.
Clostridium perfringens has a unique micro morph for a gram + bacterium. Describe it.
large “box-car” rods
