Intro and Gram postive bacteria disease Flashcards
Gram stain limitaitions
These microbes may lack real colors
Treponema (too thin to be visualized) Mycobacteria (high lipid content) Mycoplasma Legionella (Silver stain this) Rickettsia Chlamydia (lacks muramic acid in cell wall)
Stains
Giemsa: certain bugs really try patience
Chlamydia, borrelia, rickettsiae, trypanosome, plasmodium
PAS (glycogen): Whipple/ Trepherma whipplei
Ziehl Neelsen (carbol fuschsin): acid fast (norcardia, mycobacterium)
Indian: crypto
Silver: Legionella, H pylori, fungi (pneumocystis)
Bacterial genetics
Transformation
S. pneumo, H influenza, Neisseria (SHiN)
good at taking up bacteria
Bacterial genetics
Transduction
Specialized: an excision event, lysogenic phage infect bacterium
ABCDE: genes for the following 5 bacterial toxins are encoded in lysogenic phage
ShigA-like toxin Botulinum toxin Cholera toxin Diphtheria toxin Erythorogenic toxin of Strep pyrogenes.
Staphy (all catalase positive)
Staph aureus: coagulase positive
The others: coagulase negative
then differentiate by NO StRESs
Novobiocin:
Saprophyticus is Resistant
Epidermidis is Sensitive
Gram positive branching
Anaerobe, not acid fast: actinomyces
anerobe, acid fast:norcadia
Gram positive rods
Clodistrium (anaerobe) Corynebacterium Listeria Bacillus (aerobe) Mycobacterium (acid fast)
Gram positive cocci
divide by catalase
positive= staphy
negative=strep
Hemolysis alpha
S pneumo: capsule, optochin sensntive
Viridian strep (S mutans): no capsule, optochin resistant
Alpha OVRPS
Hemolysis beta
Group A= S pyrogens: bactracin sensitive
Group B= S agalactiae: bactracin resistant
BBRAS
In addition,
S. aureus: catalase positive, coag positive
Listeria: tumbling motility, meningitis in newborn, unpasteurized milk.
Hemolysis gamma
no hemolysis
Group D = enteroccucus: growth in bile and 6.5% NaCl
Nonenterococcus (bovis): growth in bile but not 6.5%
Staph
Acute endocarditis, osteomyelitis
Protein A, thus inhibit complement fixation and phagocytosis
Staph epidermidis
Prosthetic devices and IV catheters by produing adherent biofilms.
Normal skin flora, contaminated blood cultures
Strep pneumo
Meningitis, Otitis media, Pneumonia, Sinusitis
Rusty, sputun, sepsis in sickle anemia and splenectomy
No virulence without capsule IgA protease (vs Protein A in Staph)
Viridan group Strep
Normal flora of oropharynx.
Cause dental caries (Strep mutans)
Subacute endocarditis at damaged valve (S. sanguis)
Sanguis= blood, so goes to the heart
S sanguis sticks to the heart by making glycocalyx.
Strep myrogens
JONES: to dx rhuematic fever Joint-polyarthritis O-carditis N- nodules of subQ E- erythema marginatum S-Sydenham's chorea
PHaryngitis can result in rheumatic PHever and glomerulonePHritis
Impetigo more commonly proceeds glomerulonephritis than pharyngitis
Scarlet fever: scarlet rash SPARING FACE, strawberry (scarlet) tongue, scarlet throat. (Toxin mediated more immediate reaction vs. RF is more sequelae)
strep agalactiae
Colonizes vagina
In babies, pneumonia, meningitis, and sepsis
Produces CAMP factor: which enlarges the area of hemolysis formed by S aureus
Hippurate test positive
Screen women at 35-37 wks, intraparatum penicillin is positive
Enterococci Group D
Normal colonic flora that are penicillin G resistant and cause UTI, biliary tract infection, and subacute endocarditis
Lancefield group D includes enterococci and nonenterococci, which is based on the differences in the C carbohydrates on the wall
Strep bovis (also group D)
Bacteriemia and subacute endocarditis in colon cancer patient.
Corynebacterium dipthteriae
Coryne = CLUB SHAPED
Diphtheria via exotoxin encoded by beta prophage
Pseudomembraneous pharyngitis with lymphadenopathy, myocarditis, and arrythmias
Lab: gram positive rods with metachromatic (blue and red) granules and Elek’s test for toxin
ABCDEFG ADP-ribosylation Beta-prophase C-corynebacterium D-diphteria Elongation Factor 2 Granules
Spores
Spores have dipicolic acid in the core
Spore forming gram positve in soil: Bacillus anthracis, clostrium perfringens, C tetany
Other spore formers: Bacillius cereus, C botulinum, Coxiella burnetii
C diff
Two toxins
Toxin A: enterotoxin binds to the brush border of the gut
Toxin B: cytotoxin, destroyes the cytoskeletal
Bacillus Anthrax
Bacillius anthracis: gram positve, spore forming rod
ONLY bacterium with polypeptide capsule (contains D glutamate)
Cutaneous anthrax: black eschar (painless ulcer), can lead t bacteremia and death, caused by LETHAL AND EDEMA FACTOR
Pulmonary anthrax: flu like symp rapidly progress to fever, pulm hemorrhage, mediastinitis and shock, WOOLSORTER’s disease
Bacillus cereus
Spores survive cooking rice
Keeping rice warm results in germination of spores and enterotoxin formation
Emetic tpe seen with rice and pasta: nausea and vomiting within 1-5 hrs, caused b CEREULIDE, a preformed toxin
Diarrheal type: causes watery, nonbloody diarrhea and GI pain in 8-18 hrs
Listeria monocytogenes
Facultative intracellular,
Ingestion of unpasteurized milk, cheese and deli meat or by vaginal transmission during virth
Forms actin rocket by which to move around “tumbling motility”
Cause amnionitis, septicemia and SPONTANEOUS ABORTION in pregnant women.
Granuolomatosis infantiseptica, neonatal meningitis, meningitis in immunocomp
Mild gastroenteritis in healthy
Tx: GI usually self limited, ampicillin in infants, immunocomp, and elderly for empiric treatment of meningitis
Actinomyces vs nocardia
Both form long, branching filaments assembling FUNGI
Actinomyces: gram positive anaerobe, not acid fast, normal oral flora, causes oral/facial abscesses that drain through sinus tracts, forms yellow sulrfur granules, treat with AMP
Nocardia: gram positive aerobe, acid fast, found in soil, causes pulm infectins in immunocomp, cutanous infection after trauma in immunocompetent, treat with sulfonamides
TB
Primary TB: hilar nodes + Ghon fucus ( usually in mid zone of lung) = combined called ghon complex
Secondary: fibrocaseous capitary lesion in the upper
Extrapulmonary TB:
CNS: parenchymal TB or meningitis
Vertebral body: Pott’s disease
Lymphadenitis, renal, and GI
Other mycobacteria
M kansaii: pulm TB like symp
M avium-intracellulare: cause disseminated non TB disease in AIDS, ofte resistnat to multi drugs, prophylactic treatment with azithro
All mycobacteria are ACID FAST.
Cord factor in virulent strains inhbit MP maturation and induces release of TNFa
Sulfatides (surface glycolipid) inhibit phagolysomal fusion.
Leprosy (Hansen’s disease)
Mycobacterium laprae: likes cool temperature (infects skin and superficial nerves–gloves and stocking loss of sensation), cannot be grown invitro. Reservoir in armadillos
Two types of Hansen’s
1) Lepromatous: diffusely over the skin and communicable, characterized by low cell mediated immunity with a humoral TH2 response
2) tuberculoid: limited to a few hypoesthetic hairless plague, characterized by high cell mediated immunity with largely TH2 type immune response
LEpromatous can be LETHAL
Multidrug therapy: dapsone, rifampin for 6 months for tuberculoid form
Dapsone, rifampin and flofazimine for 2-5 years for lepromatous form.
