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Second Year Microbiology > Disease Causing Pathogens > Flashcards

Disease Causing Pathogens Flashcards

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1
Q

How could you diagnose an infection with Staphylococcus aureus? What would it cause? How could it be treated?

A

Diagnosis:

  • Growth on BP selctive media (shiny, grey)
  • ELISA ST enterotoxin
  • Phage Typing

Disease:

  • Intoxication: vomiting

Treatment:

  • Rehydration
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2
Q

How could you diagnose an infection with Clostridium perferingens? What would it cause? How could it be treated?

A

Diagnosis:

  • PCR for LT toxin

Disease:

  • Intoxication: diarrhoea (bacteria sporulate in gut)

Treatment:

  • Rehydration
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3
Q

How could you diagnose an infection with Bacillus cereus? What would it cause? How could it be treated?

A

Diagnosis:

  • Blue growth on indicator and selective BCSA medium (egg yolk, polymyxin, pH indicator)
  • Mannitol negaitve

Disease:

  • Intoxication: Vomiting (ST toxin)
  • Intoxication: Diarhoea (LT toxin)

Treatment:

  • Rehydration
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4
Q

How could you diagnose an infection with Campylobacter jejuni ? What would it cause? How could it be treated?

A

Diagnosis:

  • Grow on selective, enriched CAMP media
  • Antibiotics, blood, pyruvate, vit B6 (42C)
  • Motile: H antigens
  • Microaerophillic growth: 42C, 5-10% O2

Vibrionaceae Growth Characteristics

  • G- slender rods
  • Facultative anaerobe
  • Oxidase Positive
  • Media needs 1% salt
  • Fermentative metabolism

Disease:

  • Dysentery (invade and toxin produced)

Treatment:

  • Rehydration
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5
Q

How could you diagnose an infection with Salmonella? What would it cause? How could it be treated?

A

Diagnosis:

  • LNF (yellow) on MAC and DCA
  • Precipitate in selinite broth (selective)
  • H2S producer, black dot colonies on DCA
  • Phage typing
  • O and H antigens (motile)

Enterobacteriaceae Growth Characteristics:

  • G- rods
  • Facultative anaerobe
  • Oxidase Negative
  • Simple media growth
  • Fermentative glucose metabolism

Disease:

  • Diarrhoea (Invasive, Sip, T3SS, Ssa)

Treatment:

  • Rehydration
  • Antibiotics rarely used
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6
Q

How could you diagnose an infection with Shigella? What would it cause? How could it be treated?

A

Diagnosis:

  • LNF (yellow) on MAC and DCA
  • No H antigens (Non motile)
  • Serotype O antigens
  • Non H2S on DCA

Enterobacteriaceae Growth Characteristics:

  • G- rods
  • Facultative anaerobe
  • Oxidase Negative
  • Simple media growth
  • Fermentative glucose metabolism

Disease:

  • Dysentery (inasive, Ipa, T3SS, IcsA, cytotoxic shiga toxin)

Treatment:

  • Antibiotics if severe
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7
Q

How could you diagnose an infection with ETEC? What would it cause? How could it be treated?

A

Diagnosis:

  • PCR for LT, ST toxins
  • LF (pink)

Enterobacteriaceae Growth Characteristics:

  • G- rods
  • Facultative anaerobe
  • Oxidase Negative
  • Simple media growth
  • Fermentative glucose metabolism

Disease:

  • Traveler’s diarrhoea (non-invasive)

Treatment:

  • Rehydration
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8
Q

How could you diagnose an infection with EPEC? What would it cause? How could it be treated?

A

Diagnosis:

  • PCR for BfpA gene, eae gene (intimin)
  • Immunofluroescence actin stain
  • LF (pink)

Enterobacteriaceae Growth Characteristics:

  • G- rods
  • Facultative anaerobe
  • Oxidase Negative
  • Simple media growth
  • Fermentative glucose metabolism

Disease:

  • Infant diarrhoea (Non-invasive, T3SS, tir, intimin, A/E)

Treatment:

  • Rehydration
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9
Q

How could you diagnose an infection with EHEC? What would it cause? How could it be treated?

A

Diagnosis:

  • Growth on SMAC
  • EIA for shiga toxins (STX1, STX2)
  • PCR for eae (intimin), STX1, STX2 genes
  • LF (pink)

Enterobacteriaceae Growth Characteristics:

  • G- rods
  • Facultative anaerobe
  • Oxidase Negative
  • Simple media growth
  • Fermentative glucose metabolism

Disease:

  • Diarrhoea, dysentery, HUS
  • (A/E, cytotoxic shiga toxin)

Treatment:

  • Rehydration for diarrhoea
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10
Q

How could you diagnose an infection with Yersinia enterocolitica? What would it cause? How could it be treated?

A

Diagnosis:

  • LNF (yellow)
  • Urease postive
  • Bulls eye colonies on CIN
  • Psychrotrophic growth (cold)

Enterobacteriaceae Growth Characteristics:

  • G- rods
  • Facultative anaerobe
  • Oxidase Negative
  • Simple media growth
  • Fermentative glucose metabolism

Disease:

  • Mistaken for appendicitis
  • Diarrhoea (invasive, T3SS, YopP, YopM)

Treatment:

  • Rehydration
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11
Q

How could you diagnose an infection with Vibrio cholerae ? What would it cause? How could it be treated?

A

Diagnosis:

  • Yellow on TCBS selective indicator medium

Vibrionaceae Growth Characteristics

  • G- slender rods
  • Facultative anaerobe
  • Oxidase Positive
  • Media needs 1% salt
  • Fermentative metabolism

Disease:

  • Asymptomatic possible
  • Profuse diarrhoea (Rice water)
  • (Non invasive, Tcp adhesin, AB5 toxin)

Treatment:

  • Rehydration
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12
Q

How could you diagnose an infection with Vibrio parahaemolyticus ? What would it cause? How could it be treated?

A

Diagnosis:

  • Green on TCBS selective indicator medium

Vibrionaceae Growth Characteristics

  • G- slender rods
  • Facultative anaerobe
  • Oxidase Positive
  • Media needs 1% salt
  • Fermentative metabolism

Disease:

  • Explosive diarrhoea, vommiting
  • (Invasive)

Treatment:

  • Rehydration
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13
Q

How could you diagnose an infection with Rotavirus? What would it cause? How could it be treated?

A

Diagnosis:

  • Electron microscopy
  • ELISA for antigen

Disease:

  • Child Diarrhoea (protein NSP4 like enterotoxin)

Treatment:

  • Rotateq- oral live attenutated vaccine
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14
Q

How could you diagnose an infection with Norovirus (Calicivirus)? What would it cause? How could it be treated?

A

Diagnosis:

  • Electron microscopy
  • EIA for antigen
  • RT PCR for RNA in stool

Disease:

  • Adult diarrhoea (bind histo blood antigens, A and O best)
  • Asymptomatic common

Treatment:

  • Rehydration
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15
Q

How could you diagnose an infection with Adenovirus? What would it cause? How could it be treated?

A

Diagnosis:

  • Electron microscopy
  • Antigen detection

Disease:

  • Diarrhoea, vomitting

Treatment:

  • Rehydration
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16
Q

How could you diagnose an infection with Giardia lamblia? What would it cause? How could it be treated?

A

Diagnosis:

  • Microscopy for cysts/trophozoites in stool
  • Antigen in stool

Disease:

  • Giardiasis
  • Grumbly diarrhoea (non invasive, gut malabsorption)

Treatment:

  • Metronidazole (pro drug for anaerobic metabolism)
  • Prevent by boiling, filtering water
17
Q

How could you diagnose an infection with Cryptosporidium? What would it cause? How could it be treated?

A

Diagnosis:

  • Microscopy for oocysts in stool (acid fast stain)
  • Antigen detection in stool

Disease:

  • Cryptosporidosis - diarrhoea, vomiting
  • (non invasive, proteases and binds glycoproteins)
  • Worse if immunocompromised

Treatment:

  • Immunocompetent: nitazoxanide
  • Immunocompromised: supportive therapy, boost immune system, rehydration
18
Q

How could you diagnose an infection with Entaemoeba histolytica? What would it cause? How could it be treated?

A

Diagnosis:

  • Microscopy for cysts/trophozoites in faeces (iodine stain)
  • Antigens in stool
  • Antibodies in sera (but doesn’t tell if new or old

Disease:

  • Amoebic dysentery (invasive, kills cells, cysteine protease against IgG and IgA)
  • Mild = diarrhoea and cramps

Treatment:

  • Metronidazole (prodrug against anaerobic metabolism)
19
Q

How could you diagnose an infection with Clostridium difficile? What would it cause? How could it be treated?

A

Diagnosis:

Disease:

  • Pseudomembranous Colitis (adhere, toxins, cell death)
  • Recurrent infection (less diverse microbiota, dysbiosis)

Treatment:

  • Faecal transplant/bacteriotherapy (recurrent infection)
20
Q

How could you diagnose an infection with Influenza Virus? What would it cause? How could it be treated?

A

Diagnosis:

  • Rapid Diagnosis- RT-PCR (A vs B, strip with antibody and colour change)
  • Culture (strain/subtype, allantoic fluid, HI tests)
  • Detect ab responses (HI test with patient serum, 4 fold rise in titre)

Disease:

  • Fever, chills, aches, pains, cough (replicates in airway SA2-6, tissue damage, inflammation, cyotkines, IFN)

Treatment:

  • Trivalent vaccine (H1N1, H3N2, B) for at risk groups- grown in eggs
  • NA Inhibitor antivirals (agaisnt type A and B. Relenza/Zanamivir inhaled, Tamiflu/Oseltamivir oral prodrug- but some resistance)
  • Ion Channel Blocker antivirals (adamantanes, inhibit uncoating, only against type A, lots of resistance)
  • Designer Drugs- Sialic acid analogues, bind and block NA active site
21
Q

How could you diagnose an infection with Ebola Virus? What would it cause? How could it be treated?

A

Diagnosis:

  • Lab tests on antigens

Disease:

  • Sudden onset: vomiting, diarrhoea, haemorrhaging, loss of kidney/liver function
  • Unusually high virulence and contagious (direct fluid contact)

Treatment:

  • No vaccine, experimental drugs controverisal
22
Q

How could you diagnose an infection with Streptococcus pneumoniae? What would it cause? How could it be treated?

A

Diagnosis:

  • Clinical (history, signs, symptoms)
  • Lab (blood, sputum, serum)- microscopy, , ab detection, antibody detection
  • Culture (A haemolysis on HBA, optochin sensitive)

Disease:

  • Asymptomatic
  • Pneumonia (LRT infection, inflammation of lungs, cough, fever, pain, breathing difficulties)
  • Variable onset, symptoms, presentation
  • Community acquired or hospital acquired
  • Non-Invasive disease (local, pleural effusion) or invasive disease (blood, CNS+Meningitis)
  • Damage via H2O2, pneumolysin, autolysin, complement activation (CRP)
  • Middle ear infection

Treatment:

  • Supportive (bronchodilators, O2)
  • Penicillin (resistance: modified PBPs), cephalosporins
  • Vaccine (23V polysaccahride, 13V conjugate)
23
Q

How could you diagnose an infection with Mycobacterium tuberculosis? What would it cause? How could it be treated?

A

Diagnosis:

  • Mantoux Test (PPD, memory T cells cause inflammation)
  • IGRA (blood antigens, test for IFNY)
  • Neither show immunity or disease
  • Chest X ray
  • Acid fast bacilli in sputum
  • Culture (slow)
  • Nucleic Acid detection

Disease:

  • Tuberculosis (chronic pneumonia, fever, weight loss)
  • Infection of lung (pulmonary TB) or other organs
  • Infection = Latent TB (granuloma, 90%, non infectious, no symptoms)
  • Disease = Symptomatic TB (primary/milary spread, seondary/reactivation and caseous necrosis)

Treatment:

  • Short course therapy (RIPE for 2 months, RI for 4 months)
  • Chemoprophylaxis for latent TB to prevent reactivation
  • BCG vaccine
24
Q

How could you diagnose an infection with Mycobacterium avium complex (MAC)? What would it cause? How could it be treated?

A

Diagnosis:

Disease:

  • Colonise GIT, invade deep tissue

Treatment:

25
Q

How could you diagnose an infection with Chlamydia trachomatis (serovars D-K)? What would it cause? How could it be treated?

A

Diagnosis:

  • PCR (Swabs, first pass urine)

Disease:

  • Conjuntivits, uro-genital, Chlamydia
  • Inflamattion due to chemokines and lymphocyte activation and hsp60

Treatment:

  • Single dose of a long-acting macrolide (azithromycin) (penetrative)
26
Q

How could you diagnose an infection with Neisseria gonorrhoeae? What would it cause? How could it be treated?

A

Diagnosis:

  • PCR (Discharge, swab)
  • Microscopy (intra and extracellular G- dipplococci and polymorphonuclear neutrophils)
  • Culture (GC biplate enriched/selective medium,

Disease:

  • Gonorrhoea, uritis, PID, conjuntivitis
  • Asymptomatic
  • Inflmmation due to LPS (pus, pain)

Treatment:

  • Check antibiotic suseptibilty with culture
  • Injectable beta-lactamase resistant
    cephalosporin currently best
  • Azithromycin (chlamydia likely)
27
Q

How could you diagnose an infection with Treponema pallidum? What would it cause? How could it be treated?

A

Diagnosis:

  • Dark ground microscopy
  • PCR
  • Serology (abs to antigens, cross reactive abs)
  • RPR test (sensitve, not very specific, screens abs made agains cardiolipin)

Disease:

  • Syphilis (3 stages infection, primary-secondary-tertiary)
  • Asymptomatic possible

Treatment:

  • Long acting penicillin
28
Q

How could you diagnose an infection with HSV-1? What would it cause? How could it be treated?

A

Diagnosis:

  • Grow virus (look for antigens, abs, nucleic acid)

Disease:

  • Primary infection, reactivation
  • Localised (cold sores)
  • Disseminated (CNS: encephalitis)
  • Asymptomatic common (still secrete)

Treatment:

  • Nucleoside Analogues - Acyclovir (prodrug)
29
Q

How could you diagnose an infection with HSV-2? What would it cause? How could it be treated?

A

Diagnosis:

  • Grow virus (look for antigens, abs, nucleic acid)

Disease:

  • Primary infection, reactivation
  • Localised (genital herpes)
  • Disseminated (CNS: encephalitis)
  • Asymptomatic common (still secrete, latent as episome)

Treatment:

  • Nucleoside Analogues - Acyclovir (prodrug)
30
Q

How could you diagnose an infection with HIV? What would it cause? How could it be treated?

A

Diagnosis:

  • Antibody test

Disease:

  • Primary/acute infection (lose CD4 T cells)
  • Progresses to clinical latency
  • GALT destroyed
  • Immunocompromised

Treatment:

  • Prevention (condoms)
  • HAART (combination, durable antiviral response, less resistance)
  • Immediate antiviral therapy for postive partners
31
Q

How could you diagnose an infection with HPV? What would it cause? How could it be treated?

A

Diagnosis:

  • Pap test may show CIN, indicate abnormality

Disease:

  • Cutaneous warts (1, 2)
  • Genital warts (6, 11)
  • Genital cancer (16, 18)- PV integrated to host genome, lose E2 so lots of E6 E7 expressed
  • Epidermodysplasia Verucifromis (5, 8)

Treatment:

  • Wart removal (burn, poison, freeze, cut)
  • Immunotherapy (IFN, imiquinod/TLR7 to enhance response)
  • VLP vaccine
32
Q

How could you diagnose an infection with Legionella pneumophila? What would it cause? How could it be treated?

A

Diagnosis:

  • Urine antigen test

Disease:

  • Legionaire’s disease (pontiac fever, flu like)

Treatment:

  • Erythromycin/newer macrolides/quinolones
33
Q

How could you diagnose an infection with Dengue Virus? What would it cause? How could it be treated?

A

Diagnosis:

  • ELISA

Disease:

  • Dengue Fever
  • Acute systemic infection (fever, vomiting, fatigue, pain, headache, anorexia)

Treatment:

  • Prevent with Wolbachia (prevents mozzies laying eggs)
34
Q

In terms of HCAIs. What are risk factors? What are sources? What are means of transmission? What types of infections are common?

A

Risk Factors

  • Latrogenic (medical interventions)
  • Organisational (contamination, staff issues, layout)
  • Patient (illness, length of stay, immunocompromised)

Transmission

  • Direct, indirect, vehicle, vector

Common Infections

  • Urinary, wound, blood, skin, LRT
35
Q

How can Clostridium difficle cause HCAI?

A
  • Antibiotic Associated Diarrhoea (broad spectrum antibiotic use > disrupt gut flora > C. difficile overgrowth > diarrhoea or pseudo membranous colitis)
  • Spores (anareobic, G+ rod) hardy, contmainate surface, need soap and water to remove from hands
  • Higher carriage rate in hospitals
  • Toxin A = enterotoxin
  • Toxin B = cytopathic/ulceration
36
Q

How can Staphylococcus aureus cause HCAI?

A
  • G+ cocci, facultative anaerobe, non-motile
  • Normal in URT, nose, skin, vagina, intestine
  • Multiply/spread rapidly in tissue
  • Lots of virulence factors
  • Hardy, survive drying, adhesins, slime layer
  • Resistance (MRSA-use vancomycin)
37
Q

How can Enterococci cause HCAI?

What are feature of E. faecium in particular?

A
  • G + cocci, infect abdomen, urinary tract, blood

E.Faecium

  • Survive environment
  • Intrinsic resistance (penicillin, cephalosporin, aminoglycosides)
  • Acquired reistance (vancomycin)
38
Q

How can VRE arise?

A
  • Lots of vancomycin use, resitance genes arise in E. Faecium and E. Faecalis
  • VSE become VRE (transposon TN1549 with VanA/B locus for enzyme that affects cell wall and prevents vancomycin binding)

VRE Transmission model A

  • Patient arives with VRE and spreads it

VRE Transmission model B

  • Resistance genes transferred to VSE from anaerobic bowel flora upon vancomycin exposure
  • De novo evolution possible

Second Year Microbiology (8 decks)

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