Emerging diseases Flashcards

1
Q

C. difficile: Bacteriology and Pathogenesis

A
  • Ingested spores survive gastric acid barrier and germinate in the colon
  • Associated with acid-reducing agents
  • Colonization occurs after alteration of normal

intestinal microbiota, usually by antibiotics

• 1/3 to 2/3 of colonized patients develop clinical

symptoms

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2
Q

Bacillus spp. characteristics

A

Aerobic Gram-positive, large rods

  • Spore forming
  • Predominantly found in soil
  • Can be contaminants in laboratory cultures but can also cause infection in compromised hosts
  • B.cereus group includes Sub-sp B.cereus, B.thuringiensis, B.anthracis.
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2
Q

Necrotising Soft Tissue Infections pathogens

A
  • Group A strep is principal cause
  • Klebsiella spp.
  • Clostridium perfringens
  • E. coli
  • Staphylococcus aureus
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3
Q

Noroviral acute gastroenteritis timeline

A
  • Incubation period 24- 48h
  • Infectious period – 4h before symptoms to

48h after resolution of symptoms

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3
Q

Noroviral acute gastroenteritis sx

A
  • Clinical features: nausea, abdominal pain, vomiting ( projectile), watery diarrhoea, fever, myalgia, headache..
  • Sometimes just nausea and ? indigestion,

sometimes only diarrhoea, and sometimes

no symptoms but still infected (asymptomatic infection)

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4
Q

Chikungunya Virus: Epidemiology

A
  • Humans and Primates are the reservoir
  • Usually endemic in Africa, India, Fiji Islands, Mauritius and SE Asia
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5
Q

Chikungunya Virus: Diagnosis, prevention and control

A
  • Diagnosis by virus isolation, RT-PCR and serology
  • Prevention, No Vaccine is available, mosquito control
  • Asprin is not recommended
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5
Q

C. difficile prevention

A
  • Rational Anti-infective prescribing
  • Reduced use of acid-reducing agents
  • Commodes & the environment must be clean…
  • Hand washing by staff
  • Hands of patients can be the vector
  • Food services including food from relatives
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6
Q

NDM-1 organism characteristics

A

Gram-negative bacteria like Klebsiella

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6
Q

C.difficile tx

A

metronidazole or vancomycin

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8
Q

New Opportunities for Pathogens: Ecological Changes

A
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9
Q

What is NDM-1?

A

New Delhi metallo-ß-lactamase-1, or NDM-1 for short, is a gene carried by bacteria that makes the strain resistant to carbapenem antibiotics.

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10
Q

C. difficile structure

A

Gram-positive, spore-forming anaerobic bacillus

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12
Q

Chikungunya Virus: Pathogenesis

A
  • Incubation, 1-12 days (2-3 days common)
  • Causes fever (400C/ 1040F), arthritis, Rashes (maculopapular or petechial) and encephalitis
  • Counters type I(α andβ) INF by viral NS2 protein
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13
Q

BSE- vCJD characteristics

A

Origin is scrapie infected sheep or by mutation in cattle

  • Either way, animal concentrates fed to cattle triggered the outbreak of BSE
  • BSE jumped the species barrier ( if from scrapie) and triggered vCJD
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14
Q

Chikungunya Virus characteristics

A

Ss+ polarity RNA (Baltimore class IVb)

• Family: Togaviridae

– Genus: Alphavirus (Semliki Forest virus

complex

– Virus:Chikungunya virus

15
Q

Norovirus another name

A

Norwalk

16
Q

MERS-CoV: Epidemiology

A

4 groups;

– Alpha: Bats

– Beta: Bats

– Gamma: Birds

– Delta: Birds

18
Q

MERS-CoV: Pathogenicity

A
  • Infects bronchial epithelium
  • Evades immune attack
  • Antagonistic to INF
  • Attaches to CD26 (DPP4) peptide expressed in the bronchial epithelium and the kidneys
19
Q

Norovirus characteristics

A

possess single-stranded positive sense RNA genomes.

• Now detected by nucleic acid amplification

21
Q

MERS-CoV: Virus characteristics

A

• Ss+ Polarity RNA (Baltimore class IV)

Possibly zoonotic in nature

22
Q

Hospital water-borne infections

A
  • P. aeruginosa
  • Enteric gram-negatives
  • Legionella
23
Q

Opportunities increasing emerging diseases

A

–Changes in land use

–Rural to urban migration

–Internal displacement

–Globalization of people and goods, travel, international migration

–Medical technologies