8 Chemoprophylaxis

Question 1

define chemoprophylaxis

Answer 1

the use of an antimicrobial drug to prevent an infection

Question 2

example of chemoprophylaxis

Answer 2

use of anti-malarial drugs to prevent malaria in travellers from the UK visiting malaria endemic countries

Question 3

chemoprophylaxis should be considered when some or all of the following factors are present (6)

Answer 3

1 significant and predictable risk of infection
2 consequences of infection may be serious
3 period of highest risk can be ascertained
4 microbial cause of infection are predictable
5 antimicrobial sensitivity of the infections are predictable
6 cheap and reasonably safe antimicrobial agents available

Question 4

disadvantages of chemoprophylaxis

Answer 4

cost, adverse effects, disturbance of normal human flora, colonisation with more antibiotic resistant bacteria
selection of antibiotic resistance

Question 5

example of inappropriate chemoprophylaxis

Answer 5

long-term antibiotics to prevent UTI in in-patients with indwelling urinary catheters

Question 6

name a prophylaxis regimen for malaria

Answer 6

mefloquine (continues 1 week after leaving malarious area) or Malarone (1 week)

Question 7

prophylaxis for group A strep

Answer 7

oral penicillin given to close contacts of patients with invasive group A strep infections
given to both mother and baby if either develops it in neonatal period
for all household contacts if 2 or more cases in 30 days

Question 8

what can group B strep cause and what prophylaxis is given

Answer 8

part of normal vaginal flora, can cause neonatal meningitis and septicaemia (risk high for pre-term, low birth weigh infants)
penicillin or clindamycin is given during labour to high risk pregnancies (given to mother, cross placenta, into baby, protection during birth)

Question 9

rheumatic fever prophylaxis

Answer 9

after 1 documented attack in children, give penicillin until at least 16 years of age to prevent recurrence

Question 10

what is the prophylaxis for bacterial meningitis and meningococcal disease

Answer 10

generally only for kissing contacts, mouth-to-mouth resuscitation and same house hold
1 usually single dose of ciprofloxacin
2 ceftriaxone for pregnant women
3 rifampicin- makes oral contraceptive ineffective and stain contact lens so not generally used

Question 11

can you use prophylaxis in recurrent urinary tract infections

Answer 11

recurrent mainly in children<5 years, pregnancy and adult females
there can be a risk of kidney damage (chronic pyelonephritis) and unpleasant symptoms

Question 12

prophylaxis antibiotics in recurrent urinary tract infections

Answer 12

trimethoprim, cephalexin

Question 13

prophylaxis in splenectomised patients

Answer 13

penicillin to prevent pneumococcal infections

Question 14

opportunistic pathogens vary with type of..

Answer 14

immunosuppression

Question 15

describe a type of prophylaxis in HIV and why it’s needed

Answer 15

if HIV isn’t well controlled, CD4 drops, vulnerable to AIDS, Pneumocystic Pneumonia is a sign of developing AIDS, take co-trimoxazole to prevent recurrent PCP

Question 16

describe prophylaxis in neutropenia

Answer 16

when neutrophil count is low, at risk of developing gram-negative bacterial infections, use ciprofloxacin in periods of neutropenia to reduce risk

Question 17

what drug can be used to prevent herpes simplex virus re-activation

Answer 17

aciclovir

Question 18

what to do when an infection follows trauma/bites

Answer 18

clean it (surgical debridement), consider risk of tetanus, should have a vaccine, give a booster and antibiotic prophylaxis (co-amoxiclav)

Question 19

antibiotic prophylaxis is no longer recommended for..and who are high risk of this

Answer 19

endocarditis
prosthetic heart valves
previous endocarditis
congenital heart disease

Question 20

what are the 4 classifications of surgical operations

Answer 20

1 clean (no incision through flora)
2 clean with implant (putting something inside the body like a valve)
3 contaminated (incision into flora)
4 dirty (infection already present e.g. draining abscess)

Question 21

do you give prophylaxis for all surgical operations

Answer 21

not for clean, yes for clean with implant and contaminated, give whole course of antibiotics for dirty

Question 22

common UK surgical antibiotic prophylaxis regimens (3)

Answer 22

appendicectomy- metronidazole (1 dose)
breast implant- co-amoxiclav (1-3 doses)
cardiac surgery- cefuroxime or glycopeptide (3 doses)

Question 23

common faults with surgical antibiotic prophylaxis (3)

Answer 23

used for clean operations
given for too long (max 24 hrs only)
given without regard to previous microbiology reports or antibiotic treatment

Question 24

who is prophylaxis offered to for influenza A

Answer 24

un-immunised at risk contact of cases when influenza is circulating in the community
e.g. those over 65, pregnancy, chronic diseases

Question 25

what prophylaxis is given in influenza A

Answer 25

oseltamivir, zanamivir

Question 26

what is post-exposure prophylaxis for HIV considered for (3)

Answer 26

1 penetrating needlestick injuries
2 blood splashes to mucous membranes or non-intact skin
3 sexual contact and rape
all when source is known or strongly suspected to be HIV positive

Question 27

describe post-exposure prophylaxis for HIV

Answer 27

given within 1 hour- emergency (offered up to 2 weeks after)
combination of anti-retroviral drugs which aren’t licensed for this indication (AZT, DDI and protease inhibitors)
take for 4 weeks