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Enteric Pathogens Flashcards

1
Q

Clostridium difficile is a gram ___ bacillus

A

POSITIVE

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2
Q

Clostridium difficile - 3 types of toxins

A

Binary toxin
Toxin A
Toxin B* (cytotoxin)

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3
Q

Clostridium difficile dx

A

Test stool for toxin A/B by ELISA, PCR for gene (usually toxin B), culture

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4
Q

Clostridium difficile tx

A

Mild/moderate disease: Metronidazole (oral/IV)
Severe disease: Vancomycin 125mg PO QID (oral, not IV)
Alternatives: stool transplant, surgical (toxic megacolon)

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5
Q

Eschericia coli is a gram ____ bacillus

A

NEGATIVE

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6
Q

Bacteria that is most common cause of UTI

A

E. coli

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7
Q

5 different strains of E. Coli

A 
ETEC - Enterotoxigenic E. Coli 
EPEC - Enteropathogenic E.coli 
EIEC - Enteroinvasive E. coli
EAEC - Enteroaggregative E. coli
EHEC - Enterohemorrhagic E. coli
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8
Q

ETEC

A
  • Traveller’s diarrhea (fecal-oral)
  • Mild watery diarrhea and nausea
  • NO VOMITING
  • Usually lasts 1-4d
  • 10^8-10^10 bacteria needed to cause disease
  • Tx: Oral rehydration, dukoral available, can try empiric ABx +/- loperamide/Immodium (ie. Cipro or Azithromycin + immodium)
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9
Q

EHEC

A
  • AKA STEC (Shiga toxin producing E.Coli)
  • Includes E.Coli 0157:H7 (50%) and O104:H4 (50%)
  • (Bloody) diarrhea
  • Possible HUS (hemolytic anemia, AKI, thrombocytopenia)
  • Ingestion of cow fecal matter contaminated food/water
  • 10-100 organisms infective
  • Acts on enterocytes and endothelial cells
  • Tx: No antibiotics, supportive measures (ABX may cause bacteria to die and release more toxins)
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10
Q

2 types of salmonella

A
  1. Non-Typhoidal

2. Typhoidal

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11
Q

Salmonella is a gram _____ bacillus

A

NEGATIVE

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12
Q

2 most common non-typhoidal salmonella serotypes

A
  1. Enteritidis

2. Typhimurium

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13
Q

Non-typhoidal salmonella

A
  • self-resolving gastroenteritis
  • 10^3-10^5 organisms infective
  • Incubation:6-72h; resolves within 4-7d
  • Acute diarrhea, fever, abdo pain
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14
Q

Typhoidal salmonella

A

-typically invasive: fever, systemic symptoms (rash, headache), bacteremia
-Gastroenteritis (diarrhea and/or constipation)
-ONLY HUMANS (no animal reservoir; fecal-oral)
-can lead to intestinal perforation if left untreated
-asymptomatic carriage in gall bladder
Dx: Culture, molecular/PCR

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15
Q

Helicobacter pylori is a gram _____ bacillus

A

NEGATIVE

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16
Q

H pylori

A
  • Nausea, vomiting, epigastric pain, anorexia, acid reflux
  • Most common cause of gastritis
  • Most common chronic bacterial infection in humans
  • Fecal-oral, oral-oral
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17
Q

Non-typhoidal salmonella tx

A

No ABx required unless invasive disease or increased risk population

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18
Q

Typhoidal salmonella tx

A 
Ceftriazone or azithromycin (lots of resistance already to other Abx) 
Vaccine available (~50% effective)
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19
Q

Possible tests for H Pylori

A
  • Possible tests: urease breath test, serology (ELISA IgG), Endoscopy + biopsy
  • Test for eradication if needed = UBT ~4wks after tx
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20
Q

H Pylori tx

A

triple therapy for 2 weeks (PPI + 2 antibiotics = Lansoprazole + Clarithromycin + Amoxicillin)

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21
Q

Hep A

A
  • Fecal-oral
  • Mild, self-limiting
  • Fatigue, nausea, vomiting, diarrhea, abdo pain, fever
  • Severe: jaundice, pruritus, dark urine, pale stools
  • Extra-hepatic: cryoglobinemia, glomerulonephritis, arthritis, leukocytoclastic vasculitis
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22
Q

Hep A tx

A

Supportive, recovery in 2-3mths after infection

lifelong immunity

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23
Q

Hep A LFTs

A

ALT > AST

Transaminases >1000

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24
Q

Hep A vaccine

A

2 doses at least 6 mo apart

Can give as early as 6 mo

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25
2 common bacteria involved in food poisoning:
1. Staph aureus | 2. Bacillus cereus
26
Food bacillus cereus is found a lot in
Rice
27
Food poisoning
Acute cause, vomiting, upper GI within 1-6h after ingestion
28
Food poisoning dx
clinical
29
Food poisoning tx
Resolves within 24h without tx
30
Clostridium botulinum is a gram _____ bacillus
positive, rod, anaerobe
31
MOA of Botulinum Toxin A
Binds to receptors on neuron cell surface --> heavy chain stays on receptor while light chain gets taken into cell and damages SNARE proteins --> released ACh vesicles can't dock on post-synaptic muscle cell --> no ACh received by muscle cell
32
the 8 Ds of adult symptoms of Botulinum
1. Droopy eyelids 2. Double vision 3. Dysphagia 4. Dysarthria 5. Dizziness 6. Dry mouth 7. Descending flaccid paralysis 8. Diaphragm paralysis --> death
33
infant symptoms of Botulinum
Floppy baby syndrome = hypotonia/decreased muscle tone
34
Botulinum dx
Clinical presentation | Toxin detection in stool and serum
35
Botulinum tx
Anti-toxin (Ig) Respiratory support if necessary Mostly supportive
36
Abdominal abscess tx
(1) Empiric ABx if septic: Piperacillin-Tazobactam OR Ceftriaxone PLUS Metronidazole (2) Surgical drainage plus culture (3) Directed ABx based on culture results + anaerobic coverage (continue Metronidazole)
37
Normal gut flora
- Gram -ve coliforms: E. Coli, Proteus, Klebsiella, Enterobacter = facultative anaerobes - Anaerobes: Bacteroides (-), clostridium (+), fusobacterium (-), peptostreptococcus (+) - Gram +ve facultative anaerobes: streptococcus, enterococcus - Staph aureus - Candida
38
Most common pathogens in abdo abscesses
E. coli and Bacteroides
39
Most common pathogens in patients with ABX/hospital exposure
Candida Enterococcus Resistant gram -ve bacteria
40
Entamoeba histolytica
- Protozoa from contaminated food | - Can cause amoebic liver abscess
41
E. histolytica liver abscess dx
Imaging, serology and liver aspirate (anchovy paste)
42
E. histolytica liver abscess tx
NO SURGERY Metronidazole 5-10d Paramomycin or iodoquinol (for asymptomatic carriers)
43
Candida albicans
- Yeast | - Infection with: loss of mucosal barrier, immune deficiency, abx use
44
Common manifestations of Candida albicans
- Oral thrush in HIV | - Candida esophagitis - dysphagia, odynophagia, nausea, vomiting, anorexia
45
Candida albicans tx
Fluconazole (14-21d)
46
Fluconazole
Anti-fungal tx
47
HSV: common infections
- Herpes virus | - Oral, esophagitis, CNS, hepatitis, genital ulcers
48
HSV dx
Clinical Tissue or body fluid --> PCR Histology: viral inclusions
49
HSV tx
Acyclovir (IV/PO) Valacyclovir (PO) Prophylaxis if frequent outbreaks
50
CMV: common infections
- Herpes virus | - Esophagitis, retinitis, colitis, hepatitis, pneumonia
51
CMV dx
Clinical Elevated CMV serum viral load Tissue or body fluid --> PCR = suggest dx Histology: owl eyes (enlarged lymphocyte cell with viral inclusion) =confirms dx
52
CMV tx
Ganciclovir (IV) Valganciclovir (PO) Reduce immune suppression
53
Mycobacterium avid complex (MAC)
- Non-tuberculous mycobacteria - Found in immune suppressed - Pneumonia, colitis, disseminated disease, lymphadenitis - fever, fatigue, weight loss, diarrhea, lymphadenopathy, cough
54
MAC dx
- clinical - imaging: lymphadenopathy, pull cavity/nodular infiltrate - culture: need 2 separate resp samples, blood culture - histology: colon, bone marrow, lymph node
55
MAC tx
- Rifabutin, Ethambutol AND clarithromycin for at least 12 months - Reduce immune suppression - Azithromycin prophylaxis when CD4 count <50 (ie. HIV pts)
56
Causes of chronic diarrhea in HIV patients
Parasitic protozoa - isospora, cyclospora * treatable with Trimethoprim-Sulfamethoxazole - Microsporidia spp., cryptosporidium * immune reconstitution only
57
Strongyloides stercoralis
Parasitic helminth | -usually most evident in immunosuppressed patients
58
Infections from recent travel
- ETEC - EAEC - Campylobacter
59
Infections from day care centres
- EHEC - Shigella - Norovirus - Rotavirus
60
Infection from health care exposure
-C. difficile
61
Infections common in immune compromised
- Protozoa - MAC - CMV
62
Infections common in young people
- HUS - Rotavirus - Shigella
63
Infections common in old people
- C. Diff - Salmonella - HUS
64
Empiric tx for febrile, inflammatory diarrhea in immunosuppressed host
3rd gen cephalosporin or ciprofloxacin
65
Pathogens that should be considered for tx if symptomatic
- Shigella - Campylobacter - E. histolytica - C.diff
66
Pathogens that should NOT be considered for tx
- EHEC (risk of HUS) | - Salmonella in a healthy host
67
Pathogens that MAY be treated even if asymptomatic
- Shigella to reduce spread in high risk settings (MSM, day care) - Salmonella in chronic carriers at high risk of transmission (food workers) - Entamoeba histolytica to prevent progression to invasive disease
68
Mild C.diff
WBC <15 000 cells/uL AND serum creatinine <1.5x premorbid level
69
Severe C.diff
WBC >15 000 cells/uL OR serum creatinine level >/=1.5x premorbid level
70
2 alternatives to vancomycin for severe C.diff
1. Fidaxomicin | 2. Increase to 500mgQID PO + metronidazole = combo therapy (only for critically ill)
71
Recurrent C.diff tx
1. Treat again with vancomycin (QID until better, BID for 1 wk, OD for 1wk, q2d, q3d, then stop 2. Stool transplant (FMT) -- good but not always available
72
Giardia lamblia
Intestinal protozoa
73
Giardia lamblia tx
1st line in Canada = Metronidazole | 1st line where available = Tinidazole
74
Cystisospora belli
Intestinal protozoa
75
Cystisospora belli tx
Self-limited in healthy hosts | Trimethoprim/Sulfamethoxazole (TMP-SMX) if prolonged
76
Cyclospora cayetanensis
Intestinal protozoa
77
Cyclospora cayatanensis tx
Self-limited | Trimethoprim/sulfamethoxazole if prolonged
78
Cryptosporidium hominis tx
In HIV pt - HAART | In immune competent pt - self-limited (maybe nitazoxanide)
79
Blastocystis hominis
Intestinal protozoa | Commonly found in asymptomatic individual
80
Blastocystis hominis tx
Can consider MTZ, iodoquinol, paromomycin or TMP-SMX
81
Dientamoebe fragilis
Intestinal protozoa
82
Dientamoebe fragilis tx
If diarrhea >1wk and no other potential pathogen found, consider tx with MTZ, iodoquinol, paromomycin, tetracycline
83
Entamoeba dispar
Intestinal protozoa
84
Entamoeba dispar tx
No tx needed
85
Non-antibiotic tx for infectious diarrhea
- ORS (most effective) - Anti-emetics (ie. ondansetron, metoclopramide, domperidone) - Anti-diarrheals (ie. imodium/loperamide)
86
Ondansetron MOA
5HT3 antagonist -- specific serotonin receptor blocked such that serotonin cannot trigger vagal afferents to activate commit centre in brain
87
Metoclopramide, domperidone MOA
dopamine antagonist -- blocks dopamine receptors in chemoreceptor trigger zone in CNS (plus can block 5HT3 at high dose)
88
Which drug should be avoided in children/adults with fever or abdominal distention?
Anti-diarrheals | Risk of ileus
89
Loperamide MOA
u-opioid receptor agonist in myenteric plexus of LI --> decreases muscle contraction in LI = decreased gut motility
90
Tx NOT recommended for gastroenteritis
- Clay minerals (kaopectate) -- no evidence - Antispasmodics -- increased risk of toxic megacolon - Vit A -- no benefit in acute epis - Diphenoxylate/atropine (lomotil) -- not for infectious gastroenteritis - Opiates should be avoided f possible
91
Recommended prophylactic tx for TD
- Basic hygiene practices - Fluoroquinolone chemoprophylaxis (high risk pts) - Rifampin chemoprophylaxis (high risk pts) - Bismuth subsalicylate (anti-secretory agent)
92
Top causes of fever
- Malaria - Arbovirus: Dengue, Chikungunya, Zika - Typhoid - Rickettsial fevers
93
Malaria
- Returning traveler has malaria unless proven otherwise - Fevers, rigors, headaches, myalgia, anorexia - Severe: end organ dysfunction
94
5 Malaria species
``` P. falciparum P. vivax P. ovale P. malariae P. knowlesi ```
95
Malaria dx
Thick and thin blood smears; 3 smears 12-24h apart | Rapid antigen tests (can't determine parasitemia)
96
Malaria tx
Severe pt: 1st line: Artesunate IV + doxy or clindamycin 2nd line: Quinine IV + doxy or clindamycin Uncomplicated pt: 1st line: Arthemeter-Lumefantrine (not avail in Canada) Others: Atovaquone-Proguanil (Malarone), Quinine + doxy/clindamycin, chloroquine Treating oval and vivax (dormant forms in liver): chloroquine + primaquine*
97
Arbovirus - big 3
Dengue fever Chikungunya Zika
98
Arbovirus
Fever, arthralgia, myalgia, headache, blanching rash of dengue, nausea, vomiting, diarrhea, conjunctivitis (zika), low plts (dengue)
99
Zika complication
Sexual and materno-fetal transmission Fetal microcephaly if infection in utero Infected/potentially-infected reproductive aged women: no attempts at conception for 2 months Infection/potentially-infected men: no unprotected sex for 6 months
100
Dengue complication
Hemorrhagic fever or shock syndrome | Required back to back infections
101
Chikungunya complication
Persistent post-infectious arthralgia
102
Zika dx
PCR if <10d from symptom onset + serology
103
Dengue and chikungunya dx
Serology, acute and convalescent needed
104
Arbovirus tx
Supportive care only
105
Typhoid
``` Salmonella type Fecal-oral; contaminated water Prolonged fever (minimum 3d), fatigue, headache, +/- cough, constipation (adults), mild diarrhea (kids), apathy, neurocognitive findings ```
106
Typhoid complications
~2wks after illness Usually GI related b/c hangs out in Peyer's patches Intestinal perforation, GI bleed, sepsis
107
Typhoid dx
Blood culture
108
Typhoid tx
Ceftriaxone or azithromycin
109
Rickettsial fevers
Spread by fleas, ticks, lice, mice Some have rash, fevers Can be life threatening
110
Rickettsial tx
DOXYCYCLINE (for all types)
111
C. diff symptoms
- Watery, foul smelling diarrhea - Elevated WBCs without appearing very sick - Mild abdo discomfort - Pseudomembranous colitis (severe) - Toxic megacolon (severe)

Medd 422 (4 decks)

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