""

Question 1

**A patient has a lung infection. List three ways to collect a sample from them

Answer 1

Nasopharyngeal aspirate
Throat swab
Broncho-aleveolar lavage
Nasopharyngeal swab
ET secretions

Question 2

***List four bacteria that can be cultured from a patient with a lung infection

Answer 2

Mycobacterium tuberculosis
Legionella pnuemophilia
Streptococcus pneumoniae
MRSA

Question 3

Explain why looking at sputum and doing a tissue stain is useful

Answer 3

Staining bacteria makes it visible and helps identify gram +ve or -ve
Allows direct identification and visualisation
Sputum is the least invasive method

Question 4

***What is meant by nosocomial infection and when can it be diagnosed?

Answer 4

Hospital-acquired infection

Infection acquired after exposure to healthcare

48 hours after admission

Question 5

**What causes nosocomial infection?

Answer 5

High concentrations of patients in one area

Dissemination by medical staff

Interventions e.g catheterisation, prosthetics, lines, etc.

Question 6

**Name 3 hospital acquired microbes

Answer 6

ESCAPE

Enterococcus fasciae
Staphylococcus aureus
Clostridium difficile
A. baumanii
Pseudomonas aeruginosa
Enterobacteriacae (E .coli, K. pneumoniae, Enterobacter spp)

Question 7

Give an example of a gram positive infection, say what antibiotic it is resistant to and say how the antibiotic works

Answer 7

Methicillin-resistant staphylococcus aureus
Methicillin
β-lactam
inhibits peptidoglycan synthesis by binding to penicillin binding proteins
Resistance: bacteria can encode new PBP = PBP2a which has low affinity for methicillin

Klebsiella pneumonia (also E.coli)
Cephalosporins
Beta lactam
inhibits peptidoglycan synthesis by binding to penicillin binding proteins
Resistance: bacteria encode ES beta lactamase enzyme via a plasmid, cleaves ab

Pseudomonas aeruginosa
Carbapenems
Beta lactam
inhibits peptidoglycan synthesis by binding to penicillin binding proteins
Resistance: bacteria encode carbapenemase
enzyme to cleave the ab on a transposon

Enterococcus faecium
Vancomycin
Targets peptidoglycan precursor molecule to inhibit PtG synthesis
Resistance: E. faecium encodes other protein precursors for PtG
synthesis (plasmid and transposon)

Question 8

Name 2 examples each of flagellae and coccidiae and the diseases they cause

Answer 8

Protozoae = amoebae, coccidiae, ciliates, flagellates
Amoebae
E. histolytica -> amoebiasis: liver abscess, dysentery
[E. dispar is a commensal]

Flagellates
Leishmania: leishmaniasis (visceral or cutaneous)
Trichanomonas: trichomoniasis: vaginal discharge, dysuria, vulval itching / ulcers / odour

Coccidiae
Plasmodium e.g. P. ovale / malariae / falciparum: malaria (anaemia, cerebral oedema)
Toxoplasma gondii: toxoplasmosis (retinochoroiditis, brain lesions, pneumonitis)

Ciliates
Balantidium coli: balantidiasis (diarrhoea, vomiting, abdo pain, often no sx)

Question 9

State 2 helminth infections

Answer 9

Roundworms (nematodes):filiariae, hookworm, ascariasis, strongyloides

Flatworms (cestodes): taenia

Flukes (trematodes): schistosoma
Ascaris lumbricoides, ancyclostoma duodenale, trichuris trichura, lymphatic filiarisis, T. solium

Question 10

Give 3 examples of bacterial pathogens that can be vaccinated for

Answer 10

Streptococcus pneumoniae
Neisseria meningitidis
Haemophilus influenzae

Question 11

Name 4 types of protozoa and give an example of each

Answer 11

Amoeba - Entamoeba hystolytica
Coccidia - Balantidium coli
Cilliate - plasmodium spp, toxoplasma gondii
Flagellate - leishmania, trichomonas

Question 12

What is the difference between protozoa and metazoa

Answer 12

Single celled vs multicellular
Cannot cause eosinophilia vs can cause eosinophilia
Can replicate in man vs cannot
Insect vectors, intermediate hosts and vectors

Question 13

Define an outbreak

Answer 13

Greater than expected number of individuals infected or diagnosed with a particular infection within a particular area or a given timespan, or both

Question 14

How are outbreaks measured and why is it important

Answer 14

Surveillance of disease incidence
Good and timely reporting systems neccessary
Use PCR to detect the outbreak strain

1. Identify the source of the outbreak
2. Stop the outbreak from spreading any further / contain it
3. Treat sufferers / prevent others from becoming infected
4. Prevent similar outbreaks occurring in the future

Question 15

What are the five steps of investigating an outbreak?

Answer 15

Preliminary investigation
Case definition and identification
Descriptive stidy
Analytic study
Control

Question 16

Outline the bacteria in the E. coli outbreak became more virulent

Answer 16

EAEC obtained the ability to produce shiga toxin from bacteriophage transfer with EHEC

Question 17

Give three characteristics of the bacterium causing the 2011 E. coli outbreak

Answer 17

Produces shiga toxin from prophage, disrupt protein synthesis
ESBL plasmid: produces wide-spectrum β-lactamases
pAA plasmid: aggregative adhesion fimbrial operon
+ biofilm

Question 18

List three symptoms of haemolytic uremic syndrome

Answer 18

Acute renal failure
Haemolytic anaemia
Thrombocytopenia

Question 19

What are endotoxins and exotoxins?

Answer 19

Endotoxins - Lipase A moiety of LPS on the outer membrane of gram -ve bacteria

Exotoxins: Toxin released by bacteria into its surroundings

Question 20

Name 2 virulence factors of bacteria and which each uses

Answer 20

Varied secretion systems - Type 3 (salmonella), type 4 (C. jejuni, legionella pneumophilia)
Pili - Neisseria gonnorheae
Capsule - protect against phagocytosis
Flagella
Endospores - clostridium
Biofilm