Chlamydia

Question 1

Prevalence of chlamydia in the 16-24 year olds and sexually active

Answer 1

16-24 year olds= 2-3%

Sexually active = 1-2%

Question 2

What is the risk of PID in chlamydia

Answer 2

17% if not treated, also risk of tubal factor infertility and ectopic pregnancy due to scarring in the fallopian tubes

Question 3

What is the treatment of chalmydia

Answer 3

Azithromycin 1gram and Doxycyclind 100mg bd for 7/7

Question 4

What is the R0

Answer 4

The number of new infections produced by an infected individual in a populatins with no immunity in the absence of any intervention

Question 5

What are the components of Ro

Answer 5

B - the probability of transmission
C - the rate of partner acquisition
D - the duration of effectiveness

Question 6

What was the original mathematical model that lead to the National Screening Programme

Answer 6

Thought if we screened 35% of women aged 16-24 we could reduce chlmaydia prevalence from >6% to less than 2% in 10 years

Question 7

What was the aim and resutls of the National Chlamydia Screening Programme

Answer 7

Aimed to screen 30% of women aged 15-24 to identify asymptomatic to treat them to prevent adverse sequaelae and further infections

2004 began, 2008 uptake complete, 2011 40% Women and 20% of men screened

However resistance remained about 3%

Question 8

Why was the national chlamydia screening programme wrong

Answer 8

1) Could have been chagne in sexual behaviour –> didnt occur
2) Variances in transmission probablility –> i.e. varies with infectious load and innate/acquired immunity
3) Duration of infection: i.e. differences between asymptomatic and symptomatic patients

Question 9

What is the duration of infection in asymptomatic wmoan

Answer 9

75% had chlamydia for 1.26 years

25% had passive infecton –> resolves very quickly

Question 10

What is the duration of infection in asymptomatic men

Answer 10

2/3 had chlaymdia for 2.84 years

1/3 had passive infection

Question 11

Why is more difficult for men to acquire chlamydia

Answer 11

As only exposed to vaginal secretions during intercoruse

Question 12

What is the incubation period for symptomatic patients

Answer 12

in men 4 weeks before urethritis

In women may be months before PID

Question 13

Was is the transmission probablility of chlamydia

Answer 13

10% of risk per episode for sexual intercourse

HOWEVER doesnt accoutn for those who spontaneoulsy resolve their infections

Question 14

Briefly describe the life cycle of C. Trachomatis

Answer 14

Elementary body infects –> transforms into reticulate body –> Binary dission –> favourable conditions than tranforms into EB and can be released from the cell

If unfavourable growth conditions then can transform into persistent RB

Question 15

What cells do chlamydia infect

Answer 15

NOn squamous columna epithelial cells

Question 16

what factors contribute to chlamydia persistance

Answer 16

Cellular biology: abherrant reticulate odeis
Adaptive immune response: CD4, IFN-Y and BV
Sub-optimal management: Antimicrobial resistance and re-infection

Question 17

What are mucins

Answer 17

Secreted proteoglycansm gel forming

Question 18

What cytokine is important for the clearance of chlamydia

Answer 18

IFN-Y –> this induces the expression of indolaemine 2-3-dioxygenase –> this degrades intracellular tryptophan which is then lethal to chlamydia as tryptophan is key to chalmydia persistence

Question 19

What is clamydia viral load

Answer 19

Massive variation in levels reported in vaginal fluid and semen; 10 grams to >1mil per ml in vaginal fluid

Higher loads are associated with a younger age and increased inflammation

Question 20

How does hormonal milieu affect chalmydia and epithelial cells

Answer 20

Oestrogen dominant phase of menstrual cycle –> promotes attachment and may promote a persistent phenotype due to stress response and latency cgenes

Progesterone phase –> promotes energy utilisation

Question 21

What is BV

Answer 21

Normally a lactobacilli dominant in the vagina

However in BV in 10-20% of women this is replaced by polymicrobial anaerobic flora

Question 22

Why do you have a higher risk of acquiring chlamydia if you have BV

Answer 22

1) Altera cell barrier –> mucinases (sialadases) decrease the efficacy of the mucin body and degrade IgA and lactoferrin and participate in biofilm formation
2) Indole production and immune evasion –> tryphohytan synthesised and protects from the lethal effects of IFN-Y