Opportunistic Infections

Question 1

What are the frequently encountered opportunistic pathogens?

Answer 1

E coli, staph aureus, klebsiella pneumoniae, enterococcus, pseudomonas aeuriginosa, enterobacter, serratia, proteus, clostridium difficile

Question 2

Which pathogens may cause nosocomial epidemics?

Answer 2

staph aureus, klebsiella pneumoniae, enterococcus, pseudomonas aeuriginosa, enterobacter, serratia

Question 3

What are some local host factors which may put the patient at risk of opportunistic infections?

Answer 3

anatomical defects, wounds, burns, catheters, foreign bodies

Question 4

What are some systemic host factors which may put the patient at risk of opportunistic infections?

Answer 4

extremes of age, leucopenia, malignancy, malnutrition, diabetes, liver disease, infection, treatment with antimicrobials, congenital immunodeficiency

Question 5

What are the sources of the pathogens in an opportunistic infection?

Answer 5

either endogenous (patients own microbiota) or exogenous (someone else’s microbiota)

Question 6

What must be considered in the treatment of opportunistic infections?

Answer 6

antibiotic susceptibility because nosocomial strains are often resistant and whether the patient is immunocompromised so will require bactericidal instead of bacteriostatic antibiotics

Question 7

What is the most important prevention method of opportunistic infections?

Answer 7

aseptic technique (hand hygiene)

Question 8

What are the features of pseudomonas?

Answer 8

gram negative rod, aerobic (strict or facultative), motile, non fermenting, non sporing, catalase and oxidase positive

Question 9

Why does pseudomonas have a distinctive colour and smell?

Answer 9

because some species produce a pigment called pyocyanin which is green with a sweet odour

Question 10

What environment do pseudomonas live in?

Answer 10

moist environments

Question 11

What tests are used epidemiologically to figure out if the same strain of pseudomonas is causing the problem?

Answer 11

RFLP or MLST

Question 12

What are the different species of pseudomonas?

Answer 12

pseudomonas aeuriginosa, burkholderia cepacia, senotrophomonas maltophilia, burkholderia pseudomallei

Question 13

What does burkholeria pseudomallei cause?

Answer 13

pneumonia (meliodosis) - particularly in NT

Question 14

Which patients are particularly at risk of an opportunistic infection from pseudomonas?

Answer 14

cystic fibrosis patients

Question 15

Why is pseudomonas aeuriginosa difficult to treat?

Answer 15

because all strains are intrinsically resistant to antibiotics and weak disinfectants and can readily acquire resistance from other bacteria

Question 16

What superficial infections are caused by pseudomonas aeruginosa?

Answer 16

otitis externa, folliculitis, keratitis, corneal ulcer

Question 17

What deep and systemic infections are caused by pseudomonas aeruginosa?

Answer 17

pneumonia, UTI, endocarditis, osteomyelitis, septicaemia, endopthalmitis

Question 18

What features allow pseudomona aeruginosa to adhere to the epithelium?

Answer 18

flagella, pili and LPS

Question 19

What protein to the LPS core of pseudomonas aeruginsoa bind to and what implication does this have for CF patients?

Answer 19

CFTR - means that CF patients the bacteria dont adhere as well so are in the airways for longer

Question 20

What does pseudomonas aeruginosa produce?

Answer 20

a biofilm

Question 21

What are the features of pseudomonas aeruginosa when they are in a biofilm?

Answer 21

they are non motile, produce more capsule, are more adherent, less invasive, shorter LPS, slowed growth and increased resistance to antibiotics

Question 22

What is quorum sensing and what is its role?

Answer 22

communication between bacteria - allows the bacteria to know when to produce the biofilm