6/9/2017 Principles FRCEM Success
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You have scored 17%
You answered 6 correct out of 36 questions.
Your answers are shown below:
Which of the following is NOT typically present in the nasopharyngeal ora:
a) Candida spp.
b) Streptococcus spp.
c) Neisseria spp.
d) Haemophilus spp.
e) Bacteroides spp.
Something wrong?
Answer
Bacteroides spp. are typically found in the normal ora of the lower gastrointestinal tract. Species commonly found in
the ora of the nasopharynx include: Staphylococcus aureus, Staphylococcus epidermidis, Streptococcus pneumoniae,
Neisseria meningitidis, Haemophilus in uenzae, Corynebacterium spp., Moraxella spp. and Candida spp.
Notes
The normal ora provides protection against infection by competing with pathogens for colonisation sites and
resources and by producing antibacterial substances (bacteriocins) that suppress other bacteria. The natural ora
varies depending on the location in the body.
Body Site Normal Flora
Nasopharynx Streptococci, Staphylococci, Haemophilus, Neisseria, Corynebacteria, Moraxella, Mixed
anaerobes, Candida, Actinomyces
http://frcemsuccess.com/rev/sc52/ 1/38
,6/9/2017 Principles FRCEM Success
anaerobes, Candida, Actinomyces
Skin Staphylococci, Streptococci, Corynebacteria, Propionibacteria, Yeasts
Bowel Staphylococci, Enterobacteriaceae, Enterococci, Candida, Bacteroides, Bi dobacteria,
Clostridium, Peptostreptococci, Lactobacilli
Vagina Lactobacilli, Staphylococci, Streptococci, Corynebacteria, Candida, Actinomyces, Mycoplasma
hominis
Antibiotics suppress normal ora which allows for colonisation and infection by opportunistic pathogens such as
Candida albicans or Clostridium dif cile.
Which of the following microbes is spread via the respiratory droplet route:
a) Campylobacter jejuni
b) Plasmodium falciparum
c) Treponema pallidum
d) Neisseria meningitidis
e) Staphylococcus epidermidis
Something wrong?
Answer
Neisseria meningitidis is spread via the respiratory droplet route. Campylobactor jejuni is spread via the oral-faecal
route. Plasmodium falciparum is spread via a vector. Staphylococcus epidermidis is primarily spread through direct
skin contact. Treponema pallidum is spread sexually or via direct skin contact.
Notes
Infection is caused either by organisms from the host’s normal ora (endogenous infection) or by organisms
transmitted from another source (exogenous infection).
Endogenous infection will only occur if circumstances permit. For example:
Inhalation of stomach contents may cause aspiration pneumonia.
Staphylococcus aureus normally found in the nose may cause infection if inoculated into a surgical wound or
cannulation site.
N.B. Neutropenic patients are especially prone to infection from conditional pathogens.
Examples of exogenous infections include:
Salmonella enterica spread via ingested poultry.
Legionella pneumophila spread via poorly maintained air-conditioning cooling towers.
http://frcemsuccess.com/rev/sc52/ 2/38
,6/9/2017 Principles FRCEM Success
Examples of routes of transmission of infection include:
Route of Transmission Examples
Airborne Mycoplasma tuberculosis, Measles virus
Respiratory droplet Neisseria meningitidis, In uenza virus
Faecal-oral Salmonella enterica, Campylobacter jejuni
Sexual Neisseria gonorrhoea, HIV
Vector-borne Plasmodium falciparum
Transcutaneous (through intact skin) Leptospira spp., Treponema pallidum
Percutaneous (through breached skin) Staphylococcus epidermidis
Which of the following microbes adheres to the genital mucosa using mbriae:
a) Neisseria gonorrhoeae
b) Chlamydia trachomatis
c) Treponema pallidum
d) Herpes simplex
e) HIV
Something wrong?
Answer
Neisseria gonorrhoeae adheres to the genital mucosa using mbriae.
Notes
Microorganisms must attach themselves to host tissues to colonise them and each organism has a different strategy.
For example:
Microorganism Mechanism of Attachment
Neisseria gonorrhoeae Adheres to the genital mucosa using mbriae
In uenza
http://frcemsuccess.com/rev/sc52/ Attaches by its haemagglutinin antigen 3/38
, 6/9/2017 Principles FRCEM Success
In uenza Attaches by its haemagglutinin antigen
Giardia lamblia Attaches to gut mucosa via a specialised sucking disc
HIV Binds strongly to CD4 antigen
Plasmodium falciparum Causes red cell protein expression facilitating cerebral malaria
Which of the following best describes virulence:
a) The ability to cause disease
b) The ability to cause severe disease
c) The ability to produce exotoxins
d) The ability to infect the body’s own immune cells
e) The ability to cause disease in immunocompetent individuals
Something wrong?
Answer
Virulence is the ability to cause severe disease.
Notes
Important de nitions:
A pathogen is an organism that is capable of causing disease.
A commensal is an organism that is part of the normal ora.
Colonisation is a normal state and is not pathological.
Pathogenicity is the ability to cause disease.
Virulence is the ability to cause severe disease.
Infection describes a microbe-induced state of disease.
Obligate pathogens cannot survive long outside of the human body and must cause disease in order to be transmitted.
Conditional pathogens may cause disease only if certain conditions are met. For example, Bacteroides fragilis is a
normal gut commensal, but if it invades the peritoneal cavity, it will cause severe infection, or Neisseria meningitidis, a
normal nasopharynx commensal, may cause meningitis by direct or haematogenous spread.
Opportunistic pathogens usually cause infection only when the host defences are compromised. For example,
Pneumocystis jiroveci may cause lung infection in a host who has severely compromised T-cell immunity as seen in HIV
infection.
Pathogen Examples
http://frcemsuccess.com/rev/sc52/ 4/38
Dashboard Subscription expires in: 1 Days Extend
You have scored 17%
You answered 6 correct out of 36 questions.
Your answers are shown below:
Which of the following is NOT typically present in the nasopharyngeal ora:
a) Candida spp.
b) Streptococcus spp.
c) Neisseria spp.
d) Haemophilus spp.
e) Bacteroides spp.
Something wrong?
Answer
Bacteroides spp. are typically found in the normal ora of the lower gastrointestinal tract. Species commonly found in
the ora of the nasopharynx include: Staphylococcus aureus, Staphylococcus epidermidis, Streptococcus pneumoniae,
Neisseria meningitidis, Haemophilus in uenzae, Corynebacterium spp., Moraxella spp. and Candida spp.
Notes
The normal ora provides protection against infection by competing with pathogens for colonisation sites and
resources and by producing antibacterial substances (bacteriocins) that suppress other bacteria. The natural ora
varies depending on the location in the body.
Body Site Normal Flora
Nasopharynx Streptococci, Staphylococci, Haemophilus, Neisseria, Corynebacteria, Moraxella, Mixed
anaerobes, Candida, Actinomyces
http://frcemsuccess.com/rev/sc52/ 1/38
,6/9/2017 Principles FRCEM Success
anaerobes, Candida, Actinomyces
Skin Staphylococci, Streptococci, Corynebacteria, Propionibacteria, Yeasts
Bowel Staphylococci, Enterobacteriaceae, Enterococci, Candida, Bacteroides, Bi dobacteria,
Clostridium, Peptostreptococci, Lactobacilli
Vagina Lactobacilli, Staphylococci, Streptococci, Corynebacteria, Candida, Actinomyces, Mycoplasma
hominis
Antibiotics suppress normal ora which allows for colonisation and infection by opportunistic pathogens such as
Candida albicans or Clostridium dif cile.
Which of the following microbes is spread via the respiratory droplet route:
a) Campylobacter jejuni
b) Plasmodium falciparum
c) Treponema pallidum
d) Neisseria meningitidis
e) Staphylococcus epidermidis
Something wrong?
Answer
Neisseria meningitidis is spread via the respiratory droplet route. Campylobactor jejuni is spread via the oral-faecal
route. Plasmodium falciparum is spread via a vector. Staphylococcus epidermidis is primarily spread through direct
skin contact. Treponema pallidum is spread sexually or via direct skin contact.
Notes
Infection is caused either by organisms from the host’s normal ora (endogenous infection) or by organisms
transmitted from another source (exogenous infection).
Endogenous infection will only occur if circumstances permit. For example:
Inhalation of stomach contents may cause aspiration pneumonia.
Staphylococcus aureus normally found in the nose may cause infection if inoculated into a surgical wound or
cannulation site.
N.B. Neutropenic patients are especially prone to infection from conditional pathogens.
Examples of exogenous infections include:
Salmonella enterica spread via ingested poultry.
Legionella pneumophila spread via poorly maintained air-conditioning cooling towers.
http://frcemsuccess.com/rev/sc52/ 2/38
,6/9/2017 Principles FRCEM Success
Examples of routes of transmission of infection include:
Route of Transmission Examples
Airborne Mycoplasma tuberculosis, Measles virus
Respiratory droplet Neisseria meningitidis, In uenza virus
Faecal-oral Salmonella enterica, Campylobacter jejuni
Sexual Neisseria gonorrhoea, HIV
Vector-borne Plasmodium falciparum
Transcutaneous (through intact skin) Leptospira spp., Treponema pallidum
Percutaneous (through breached skin) Staphylococcus epidermidis
Which of the following microbes adheres to the genital mucosa using mbriae:
a) Neisseria gonorrhoeae
b) Chlamydia trachomatis
c) Treponema pallidum
d) Herpes simplex
e) HIV
Something wrong?
Answer
Neisseria gonorrhoeae adheres to the genital mucosa using mbriae.
Notes
Microorganisms must attach themselves to host tissues to colonise them and each organism has a different strategy.
For example:
Microorganism Mechanism of Attachment
Neisseria gonorrhoeae Adheres to the genital mucosa using mbriae
In uenza
http://frcemsuccess.com/rev/sc52/ Attaches by its haemagglutinin antigen 3/38
, 6/9/2017 Principles FRCEM Success
In uenza Attaches by its haemagglutinin antigen
Giardia lamblia Attaches to gut mucosa via a specialised sucking disc
HIV Binds strongly to CD4 antigen
Plasmodium falciparum Causes red cell protein expression facilitating cerebral malaria
Which of the following best describes virulence:
a) The ability to cause disease
b) The ability to cause severe disease
c) The ability to produce exotoxins
d) The ability to infect the body’s own immune cells
e) The ability to cause disease in immunocompetent individuals
Something wrong?
Answer
Virulence is the ability to cause severe disease.
Notes
Important de nitions:
A pathogen is an organism that is capable of causing disease.
A commensal is an organism that is part of the normal ora.
Colonisation is a normal state and is not pathological.
Pathogenicity is the ability to cause disease.
Virulence is the ability to cause severe disease.
Infection describes a microbe-induced state of disease.
Obligate pathogens cannot survive long outside of the human body and must cause disease in order to be transmitted.
Conditional pathogens may cause disease only if certain conditions are met. For example, Bacteroides fragilis is a
normal gut commensal, but if it invades the peritoneal cavity, it will cause severe infection, or Neisseria meningitidis, a
normal nasopharynx commensal, may cause meningitis by direct or haematogenous spread.
Opportunistic pathogens usually cause infection only when the host defences are compromised. For example,
Pneumocystis jiroveci may cause lung infection in a host who has severely compromised T-cell immunity as seen in HIV
infection.
Pathogen Examples
http://frcemsuccess.com/rev/sc52/ 4/38
