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Principles of Infectious Disease I Exam 1
8-27-15 thru 9-29 intro and enteric/hepatic diseases
52
Microbiology
Graduate
09/26/2015

Additional Microbiology Flashcards

 


 

Cards

Term
What steps lead to covert or overt disease?
Definition
Infection leads to colonization by parasite leads to overt/covert disease
Term

What are some sources of novel infectious agents?

Why do they spread?

Definition

zoonotic-evolution from an animal pathogen to be able to spread amongst humans

 

some old IDs that have reappeared with antibiotic resistance traits

 

human population must be sufficient to maintain spread of disease

 

Can spread due to environmental factors such as climate change, poverty, malnutrition, sociopolitical causes

 

extended contact with animals (i.e. livestock, habitat encroachment)

Term
What does our microbiome do for us?
Definition

Protection from pathogenic microorganisms

energy production-breaks down complex carbs

makes vitamins

modulates immune system

Term
Where do we get our microbiome?
Definition
amniotic fluid, birth, food, breastmilk, environment
Term
Why are infectious diseases important still (despite causing fewer deaths than in 1900?)
Definition
Although not listed on death certificates, IDs are important sequelae to events like heart attack, stoke, and diabetes that can be the actual proximal cause of death
Term
How do you measure the burden of disease?
Definition
Years of Life Lost (YLL)+ Years Lived with disability (YLD)= Disability adjusted life years (DALY) lost due to disease
Term
What are the 4 approaches to proving that an organism is the cause of an infectious disease?
Definition

Koch-Henle postulates

Bradford Hill criteria

Evan's Immunological Proof of Disease Causation

Epidemiologic evidence of causality

Term
What are three situations in which the Koch-Henle postulates cannot be satisfied?
Definition

1. organism cannot be cultured in vitro

2. no animal model exists

3. the organism cannot be cultured period.

Term
Why is Evan's Immunological Proof of Disease Causation problematic for many infections?
Definition

The presence of antibody does not always confer resistance to a disease (and lack of antibody does not necessarily confer suceptibility)

 

You can mount an antibody response without becoming ill (meaning that antibody doesn't appear during an overt disease)

Term
How would you go about proving epidemiologic evidence of causality?
Definition

1. Identify the organism associated with disease in an outbreak

2. identify organism in multiple outbreaks of same disease in different locations/times

3. study endemic manifestations of the same disease and show that the same organism is associated with the disease

4. Show that there is a common risk factor associated with infection with the organism in question

Term
Name the 4 Major categories of diarrheal diseases
Definition

Secretory diarrhea (cholera)

Invasive/inflammatory diarrhea (salmonellosis)

Persistent diarrhea

Attatching/effacing lesion producing diarrhea (eg EPEC)

Term
Why does diarrhea occur?
Definition

Disruption in net fluid output or absorption along GI tract

 

more fluid going into the intestine can be a factor

poor reabsorption can also be a factor

Term
What are the 3 kinds of reservoirs for enteric pathogens?
Definition

Humans are sole reservoir

nonhuman animal reservoir

non-animal and non-human reservoir

Term
What are the risk factors for diarrheal diseases in developed vs developing nations?
Definition

Developing nations-Poverty, poor sanitation, poor nutrition

 

endemicity of diarrhea causing pathogens

 

Developed nations-food animal reservoir, centralization of food production, food distribution networks

Term
What is different when culturing Shigella sp. vs E. coli?
Definition
Shigella tends to be lactose negative, while most E. coli are lactose positive (except EIEC, which is sometimes lactose negative)
Term

What are the classic agents of:

1. Secretory diarrhea

2. invasive/inflammatory diarrhea

3. persistent diarrhea

4. attaching/effacing leision producing diarrhea (disruption of the mucosal surface)

Definition

1. Cholera!

2. Salmonella typhimurium, enteriditis; Shigella; Bacillary dysentery (Salmonella dysenteriae)

2. Enteroaggregative E. coli (EaggEC)

4. Enteropathogenic E. coli (EPEC)

Term
What are antibiotics vs. antimicrobials vs. anti-infectives vs. antiseptics?
Definition

Antibiotics: made by bacteria/fungi that suppress growth or kill other microorganisms

 

Antimicrobial agents: anti-infective drugs made from ANY source including synthetics (used to treat bacterial and fungal infections)

 

Anti-infectives: treat any kind of infection (fungal, viral, bacterial, protozoan/helminths)

 

Antiseptics: disifect contaminated objects in the environment

Term
What are some general mechanisms of drug resistance?
Definition
  1. Alter drug target (eg penicillin binding proteins)
  2. inactivate/modify the drug (beta-lactamases)
  3. Induction of proteins that remove drug from organism (efflux pumps)
  4. Inativation/mutation of enzymes that activate the drug (M. tuberculosis catalases that activate isoniazid)
Term

What are 5 major categories of antimicrobial agents?

Definition

Beta-lactams (Cephalosporins/Carbapenams)

Aminoglycosides

Fluoroquinolones

Tetracyclines

Macrolides

Ant TB drugs

 

Term
What is the difference between a minimal inhibitory concentration vs. a minimal bacteriocidal concentration?
Definition

Inhibitory-stops bacterial growth

bacteriocidal-actively kills bacteria

Term
What are 5 "serious" antibiotic resistant bacterial pathogens?
Definition

MDR Acinetobacter (G+)

Drug resistant Campylobacter (G+)

Vancomycin Resistant enterococcus (GRAM -)

MDR Pseudomonas aeruginosa

DR Salmonella (non typhi), S. typhi

DR Shigella

MRSA

DR Strep pneumonia

DR tuberculosis

Term
What are 3 urgent threats to antibiotic resistance?
Definition

C. difficile

Carbapenem resistant enterobacteriaceae (CRE)

Drug resistant Neisseria gonorrhoeae

 

Term
2 major settings of drug resistant organism selection?
Definition

Hospitals/healthcare centers

Community

Agricultural settings (i.e. food animal production)

Term
What are 2 ways clonal drug resistant bacterial pathogens are globally diseminated?
Definition

International travel and "medical tourism"

global food trade

 

Term
What are some examples of genetic mechanisms for drug resistance?
Definition

Extrachromasomal elements:

plasmids

transposons

integrons/cassettes

movements from sp. to sp

 

Intraorganism:

point mutations/deletions

efflux pump gene expression

Term
What are 4 phenotypic changes associated with drug resistance?
Definition

Altering drug target

inactivating drug

induction of proteins that remove the drug

inactivation/mutation of enzymes that activate the drug

Term

What are 3 pathogens associated with hospital/healthcare accquired infections?

 

What are 3 pathogens associated with community infections?

 

Definition

Hospital: 

Gram positives-MRSA, VRE, C. difficile (also appearing in community settings)

 

Gram neg: many sp. Enterobacteriaceae, glucose non fermenters (Pseudomonas, Acinetobacter)

 

Community:

E. coli, Salmonella, Shigella, Yersinia, V. cholerae, Campy

E. coli UTIs, BSIs

 

 

Term
What are some gram negative Enterobacteriaceae bacteria present in hospitals?
Definition

E. coli

Klebsiella pneumonia

Enterobacter

Salmonella

 

Term
What are the 2 main components of the immune system? How do they break down?
Definition

Innate vs. Adaptive

Adaptive: humoral vs cell mediated

Cell mediated: CD8+ (cytotoxic T cells) vs CD4+ T helper cells

Th1 helper cells vs Th2 helper cells

 

Term
What links the innate to the adaptive immune system?
Definition

Antigen presenting cells (APCs): dendritic cells, macrophages

 

 

Term
How can innate immunity be exploited to increase vaccine efficacy?
Definition

Need to know which molecules will elicit the strongest innate immune response (i.e. which polysaccharide or hapten will activate PRRs)

 

which antigens should be made available to APC's to elicit a strong humoral response from adaptive immune system?

Term
What does McConkey agar select for? What does it differentiate?
Definition

Selects for gram positive vs. gram negative bacteria (gram negative grows on McConkey Agar)

 

Also differentiates between lactose fermenters and non lactose fermenters

Term
What is used to detect E. coli O157:H7 in culture?
Definition

SMAC (Sorbitol McConkey Agar culturing)

 

Term
What is detected by SMAC?
Definition
Detects fermentation of Sorbitol by bacteria with the ability to do so; non-sorbitol fermenters like E. coli O157:H7 do not activate the low pH color indicator (colonies remain colorless)
Term
What percent of all human diseases and all emerging infections are zoonotic?
Definition
60% of human disease, 75% of emerging diseases are zoonotic
Term
What is the difference between opportunistic and primary pathogens?
Definition
Opportunistic pathogens only cause disease if the host is compromise (breaching of normal barriers, decrease in immune function); primary pathogen exposure usually leads to infection and disease.
Term
What is colonization? Infection?
Definition

Infection-an organism establishes a relationship us (mutual, commensal, or parasitic)

 

Colonization: an organism not usually part of our normal flora becomes part of it (often transiently)

Term

What are the definitions of:

Parasitism

Mutualism

Commensalism

Definition

Parasitism (+/-) symbiotic relationship where the host is harmed and the colonizing organism benefits

 

Mutualism (+/_) colonizing organism benefits, host is neither harmed not helped

 

Commensalism (+/+) both host and colonizing organism benefit from the relationship

Term
Who was the last person in the world to be naturally infected with smallpox?
Definition
Ali Mao Maalin, Somalia 1997
Term
What are 3 types of asymptomatic infection?
Definition

Latent

Chronic

Convalescent

Term
what are the host factors that influence disease outcome post exposure?
Definition

host immunity/immune suppression

host genetics, age, sex

living conditions (poverty/slums)

Term

Define:

Exotoxin

Enterotoxin

Endotoxin

Definition

Exotoxin: secreted by bacteria; includes preformed toxins like Staphylotoxin A, TSS toxin, C. botulinum toxin

Enterotoxin: protein secreted by bacteria in vivo during infection (cholerotoxin, HS or HL toxin of E. coli)

Endotoxin: LPS (not a true toxin)

Term
What are the 5 immunoglobulins and what do they do?
Definition
  • IgG-protects against bacteria, viruses, toxins, increases phagocytosis, crosses placenta
  • IgA-protects against infection on mucous membranes
  • IgM-protects against early phase infection (innate)
  • IgD-receptors for activation of Bcells
  • IgE-allergic response, triggers histamine release
Term
What virus family does each of the hepatitis viruses belong to ?
Definition

A-Picornaviridae

B-Hepadnaviridae

C-Flaviviridae

D-Deltaviridae

E-Hepeviridae

Term
What kind of nucleic acid is used by each hepatitis virus?
Definition

A-RNA

B-DNA (partially circular)

C-RNA

D-circular RNA!

E-RNA

Term
What hepatitis viruses are transmitted via fecal/oral pathways?
Definition
A and E
Term
What percent of neonates become asymptomatic chronic carriers of Hep B? What about adults?
Definition

95% of babies become carriers, increased risk of liver damage and cancer

 

3-5% remain chronically infected if they get it as adults

Term
Which hepatitis virus does not have hepatotropic tendencies?
Definition

Hepatitis A

 

initially replicates in oropharynx and circulates before entering liver

Term
What are the immunologic markers of Hepatitis B during prodrome and acute phase?
Definition

Prodrome: HBsAf, HBcIgM Ab

 

Acute infection: HBcIgM Ab, HBsAg, HBeAg (correlates with high titer of HBV and high infectivity)

 

Term
what are the immunologic markers of early and late convalescence in HB?
Definition

early: HBcIgM Ab

 

Late: HBcIgM Ab, HBcAb IgG, HBsAb IgG

Term
What is the difference in immune markers in people who have had a natural infection with HBV vs. those who have been vaccinated?
Definition

Those with natural infection have HBsAb IgG AND HBcAb IgG

 

Those who have been vaccinated only have HBsAb IgG

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