Microbiology

Question 1

Clostridium difficile treatment…also recurring infection treatment

Answer 1

Metro, vancomycin and fidamoxicin

Fidamoxicin is preferred in recurrent infections since it shows less reoccurrence after treatment and higher cure rate

Question 2

What’s neomycin used for?

Answer 2

E.coli diarrhea and hepatic encephalopathy

Question 3

Hepatic encephalopathy caused by?

Answer 3

Liver dysfunction resulting in decreased detoxification capabilities and metabolic abnormalities
accumulation of ammonia (usually made by enterocytes)

activation of inhibitory
neurotransmitters
gamma-aminobutyric acid
serotonin

impairment of excitatory neurotransmitters
glutamate
catecholamines
exact mechanism unknown

Question 4

Hepatic encephalopathy treatment?

Answer 4

lactulose (nonabsorbable sugar)
acidification of the gut lumen results in ammonia trapping and less reabsorption
side effect includes diarrhea

rifaximin (nonabsorbable antibiotic)
destruction of gut bacteria result in less conversion of dietary protein to ammonia

Question 5

Fidamoxicin

Answer 5

Inhibits rna polymerase

Question 6

Campylobacter

Answer 6

most common cause of diarrhea in kids and adults in industrialized countries

Question 7

domestic animals to human infection

Answer 7

campylobacter

Question 8

campylobacter S/S

Answer 8

inflammatory meaning watery then bloody, tenesmus, leukocytes in stool, nausea etc., mimics appendicitis pain

Question 9

Guillian Barre infection

Answer 9

Campylobacter

Question 10

Preformed exotoxin in precooked foods (mayo, custards etc.), abdominal cramps and vomiting

Answer 10

Staph Aureus Food poisioning

Question 11

Shigella carriers

Answer 11

fomites in daycare, unwashed hands, contaminated food from unhygenic handling

Question 12

Bacillus Cerues toxin

Answer 12

heat stable enterotoxin

Question 13

Giardia from what?

Answer 13

contamintaed water- go camping and drink from lake etc.

Question 14

Campylobacter movement

Answer 14

corkscrew fashion

Question 15

Esophagus infectionsand immunocompromised state

Answer 15

3 infections causes esophagitis Candida > CMV> HSV

Candida: yeast and pseudohyphae/ grey white pseudomembranes on erythematous mucosa

CMV: intranuclear and cytoplasmic inclusions// linear ulcerations in distal esophagus

HSV: eosinophillic intranuclear inclusions in multinucelar squamos cells at junction// small vesicles into punched out ulcers

Question 16

HIV infections

Answer 16

esophagitis: candida, HSV CMV
meningitis: cryptococcosis
watery diarrhea: isospora belli
ring lesions in brain and chorioretinitis: toxoplasma

Question 17

Hep B and Hep D infection, how?

Answer 17

The HBsAg of Hep B needs to be coat Hep D Ag in order to infect hepatocytes

Question 18

Achalasia

Answer 18

dilated esophagus with dysphagia, can’t belch, absent peristalsis in SM of esophagus
ALWAYS DUE TO DEFECTED GANGLION MYENTERIC PLEXUS
usually due to primary condition unless pt from central or south america think chagas due to trypanosoma cruzi

Question 19

trypanosoma cruzi

insect called the reduvid bug in huts of rural huts in south america..makes a neurotoxin that causes intramural parasymp ganglion denervation..affects the LES causing dilated esophagus

Answer 19

Megaesophagus, megacolon and megaureter how?

Question 20

CMV and Toxoplasma

Answer 20

CMV causes heterophile negative mononucleosis
Toxoplasma causes mononucleosis like illness

both causes in immunocompotent

Question 21

Clostridium Botulism in infants

Answer 21

12% of honey tested to have botulism
bacteria spores germinates the gut —> intracellular toxin production–> bacteriolysis causes toxin release systemically–> weakness in the baby, more severe S/S causes diminished gag reflex, less feeding and sucking, less energy, less crying
usually constipation in baby before toxin related S/S

Dx: ELISA or PCR; mainly by S/S and hx…. stool toxins

Question 22

Cl Botulism in adults

Answer 22

preformed toxin unlike infant botulism; very severe

Question 23

Vibrio Cholerae

Answer 23

gm negative and oxidase +ve (like C jejuni but V. cholerae needs high alkaline media)
cholerae toxin related to ETEC– doesn’t invade mucosa but ACTIVATES adenylate cyclase in instestinal epithelial cells that inc cAMP and inc Cl- EFFLUX and dec Na+ reabsorption = massive watery diarrhea

also activated goblet cells to make mucus which is why we see the rice water stools

no leukocytes in this stool!

Question 24

Watery, Inflammatory and Enteric diarrhea causes

Answer 24

Watery: d/t enteroxoin

V. cholerae, Giardia, Bacillus, ETEC, microsporidia, cryptosporidia– staph aureus, e.coli, some viruses (ones i forget)

Inflammatory/ dysentery; see fecal PMNs maybe RBCs;

EHEC, shigella – C. jejuni, Salmonella, EIEC, Yersenia, Cl. difficile, Entameoba histolytica

Enteric fever; invasion and dissemination– fecal Mononuclear cells

Salmonella typhi

Question 25

charcot leyden crystals in stool

Answer 25

parasitic infection of gut

Question 26

Giardia cysts

Answer 26

ellipocidial cysts with 2 nuclei- treat with metronidazole

Question 27

south and central america

Answer 27

Argentina
Bolivia
Brazil
Chile
Colombia
Ecuador
French Guiana (département of France)
Guyana
Paraguay
Peru
Suriname
Uruguay
Venezuela

Panama, Costa Rica, Nicaragua, Honduras, El Salvador, Guatemala, and Belize

chagas; trypanosoma cruzi, reduvid bug

Question 28

southeast asia

Answer 28

consists of two distinctive different geographic regions, one is mainland Southeast Asia, also known as Indochina, on the Indochinese peninsula; it comprises the countries of
Cambodia, Laos, Myanmar (Burma), Thailand, Vietnam and West Malaysia (Peninsular Malaysia), the other is the Malay Archipelago, or Maritime Southeast Asia, which comprises the countries of:
Brunei (on the island of Borneo), East Malaysia (with the Malayan states of Sabah and Sarawak on the northern part of Borneo), all the islands of Indonesia, the Philippines, Singapore and Timor-Leste (East Timor).

stronglyoides stercolis