Australian Doctor Australian Doctor 15th September 2017 | Page 18

Grand Rounds Chlamydia conundrum THE AUTHOR SEXUAL HEALTH A surprising repeat diagnosis raises questions about antibiotic resistance and reinfection. Dr Jim Newcombe is a paediatrician, infectious diseases physician and clinical microbiologist at Royal North Shore Hospital and Douglass Hanly Moir, Sydney. HAVE AN INTERESTING CLINICAL CASE? Email the editor at [email protected]. We pay $400 for each case and photos are encouraged. L AUREN is a 21-year-old woman who presents to your practice for a routine Pap smear. Six months earlier, she had Chlamydia trachomatis screening as rec- ommended by RACGP guidelines. At that time, chlamydia PCR was positive on first pass urine. She was given a stat dose of 1g azithromycin orally. Her long-term male partner was also treated with a stat dose of 1g azithromycin orally by his GP. Lauren has remained asymptomatic. She uses Implanon for contraception, with no condom use. Both Lauren and her partner are reportedly monogamous. She has no other medical history and works as a receptionist at a financial services firm. While true resistance to antibiotics is uncommon in urogenital chlamydia infections, doxycycline is more effective than azithromycin for anorectal disease. Therefore, a rectal swab is taken for chla- mydia PCR, which is positive. Afterwards, Lauren volunteers that she engages in anal as well as vaginal intercourse with her part- ner. Her partner is also advised to seek repeat chla- mydia PCR testing. Lauren is prescribed doxycycline 100mg bd for seven days. She is advised that the efficacy of doxy- cycline therapy is very high if she adheres to the medication but that taking less than 10 doses of doxycycline is associated with a treatment failure rate of 20%. Examination and investigation Progress and follow-up On examination, the cervix is macroscopically benign. Because of the previous history of chla- mydia infection and treatment, chlamydia PCR is ordered on the ThinPrep Pap smear sample and comes back positive. Lauren is surprised and upset by this result. She asks why she is still positive and why the azithromycin treatment didn’t work. Lauren completes the course of doxycycline and says she was fully adherent. Her partner also tested positive for chlamydia on repeat urine PCR and had a further stat dose of 1g azithromycin. Lauren is keen to be retested as soon as she fin- ishes the course of doxycycline. She is advised she has to wait at least four weeks after therapy as the chlamydia PCR can remain positive during that period because of the highly sensitive nature of the assay and detection of non-viable bacterial DNA. A test of cure by urine PCR five weeks after com- pletion of doxycycline is negative. Management Lauren is counselled that around 20% of patients with a positive genitourinary/rectal chlamydia PCR result will have a further positive PCR result for C. trachomatis in the subsequent 12 months. 1 Although most repeat positive results are due to re-infection, Lauren’s sexual history, if taken at face value, argues against this. LAUREN USES IMPLANON FOR CONTRACEPTION, WITH NO CONDOM USE. SHE AND HER PARTNER ARE REPORTEDLY MONOGAMOUS. Discussion The efficacy of standard treatment regimens for urogenital chlamydia is high — 94% for azithro- CLINICAL AUDIT QUALITY IMPROVEMENT ACTIVITY TREATING CONCOMITANT ASTHMA AND ALLERGIC RHINITIS The audit focuses on more accurate diagnosis of AR in patients with concomitant asthma, which will facilitate individualised treatment plans and improved symptom control. This Australian Doctor Education Module is free-of-charge to practising GPs. EARN 40 CATEGORY 1 POINTS Sponsored by an independent educational grant from Bayer www.australiandoctor.com.au/education & AR_PRINT.indd 1 18 ADE_CA_Asthma | Australian Doctor | 15 September 2017 www.australiandoctor.com.au 5/08/16 4:57 PM