Academic Writing

You have examined three urine specimens:- Patient 1: An MSU (mid stream urine) from a 20 year old female who attended her general practitioner complaining of ‘cystitis’. Patient 2: A CSU (catheter specimen of urine) from a 75 year old male in a hospital intensive care ward where he is recovering from cardiac surgery. Patient 3: An adhesive clean catch bag sample from a 1-month old baby girl, who has been taken to hospital by her parents, this is their first child. Lab Diagnosis Each sample was serially diluted from 10-1 to 10-6 in Ringers solution, and 100μl of each sample was spread onto a plate of MacConkey, Blood and CLED agar. TEST Patient 1 Patient 2 Patient 3 Skin Squames None None Present Gram Stain of isolates Gram Negative rod Gram Negative rod Isolate 1: Gram-positive cocci Isolate 2: Gram –negative rod MacConkey 152 colourless colonies at -4 dilution 45 colourless colonies at -2 dilution 95 colonies at -3 dilution Mixture of both pink and colourless isolates Blood agar 152 white colonies at -4 dilution 45 white colonies at -2 dilution 95 white colonies at -3 dilution CLED 152 colourless colonies at -4 dilution 45 colourless colonies at -2 dilution 95 colonies at -3 dilution Mixture of both yellow and colourless isolates Biochemical Characteristics Catalase-positive Catalase-positive Oxidase-positive Isolate 1: Catalase-positive Isolate 2: Catalase-positive Indole-positive Following an antibiotic sensitive test on the Gram negative rod isolated from patient 3, the following inhibition zone (mm) were found: Ampicillin 6 Nalidixic acid 20 Trimethroprim 12 Ciprofloxacin 36 Using the above case notes determine the causative organism/s in each urine sample, justifying your answer in relation to the tests carried out. 80% Determine the number of colony forming units per millilitre (cfu/ml) in each case, showing your workings, and relate these find to Kass’s criteria. 15% Finally, using the BSAC zone interpretation table (provided below) use the antibiotic sensitivity results above for one of the organisms isolated from patient 3 to determine its antibiotic resistance and sensitivity? 5%