Intro and Gram postive bacteria disease

Question 1

Gram stain limitaitions

Answer 1

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)

Question 2

Stains

Answer 2

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)

Question 3

Bacterial genetics

Transformation

Answer 3

S. pneumo, H influenza, Neisseria (SHiN)

good at taking up bacteria

Question 4

Bacterial genetics

Transduction

Answer 4

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.

Question 5

Staphy (all catalase positive)

Answer 5

Staph aureus: coagulase positive

The others: coagulase negative
then differentiate by NO StRESs

Novobiocin:
Saprophyticus is Resistant
Epidermidis is Sensitive

Question 6

Gram positive branching

Answer 6

Anaerobe, not acid fast: actinomyces

anerobe, acid fast:norcadia

Question 7

Gram positive rods

Answer 7

Clodistrium (anaerobe)
Corynebacterium
Listeria
Bacillus (aerobe)
Mycobacterium (acid fast)

Question 8

Gram positive cocci

Answer 8

divide by catalase

positive= staphy
negative=strep

Question 9

Hemolysis alpha

Answer 9

S pneumo: capsule, optochin sensntive

Viridian strep (S mutans): no capsule, optochin resistant

Alpha OVRPS

Question 10

Hemolysis beta

Answer 10

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.

Question 11

Hemolysis gamma

Answer 11

no hemolysis

Group D = enteroccucus: growth in bile and 6.5% NaCl
Nonenterococcus (bovis): growth in bile but not 6.5%

Question 12

Staph

Answer 12

Acute endocarditis, osteomyelitis

Protein A, thus inhibit complement fixation and phagocytosis

Question 13

Staph epidermidis

Answer 13

Prosthetic devices and IV catheters by produing adherent biofilms.

Normal skin flora, contaminated blood cultures

Question 14

Strep pneumo

Answer 14

Meningitis, Otitis media, Pneumonia, Sinusitis

Rusty, sputun, sepsis in sickle anemia and splenectomy

No virulence without capsule
IgA protease (vs Protein A in Staph)

Question 15

Viridan group Strep

Answer 15

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.

Question 16

Strep myrogens

Answer 16

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)

Question 17

strep agalactiae

Answer 17

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

Question 18

Enterococci Group D

Answer 18

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

Question 19

Strep bovis (also group D)

Answer 19

Bacteriemia and subacute endocarditis in colon cancer patient.

Question 20

Corynebacterium dipthteriae

Answer 20

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

Question 21

Spores

Answer 21

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

Question 22

C diff

Answer 22

Two toxins
Toxin A: enterotoxin binds to the brush border of the gut
Toxin B: cytotoxin, destroyes the cytoskeletal

Question 23

Bacillus Anthrax

Answer 23

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

Question 24

Bacillus cereus

Answer 24

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

Question 25

Listeria monocytogenes

Answer 25

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

Question 26

Actinomyces vs nocardia

Answer 26

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

Question 27

TB

Answer 27

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

Question 28

Other mycobacteria

Answer 28

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.

Question 29

Leprosy (Hansen’s disease)

Answer 29

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.