Manual of basic techniques for a health laboratory - libdoc.who.int

208 Manual of basic techniques for a health laboratoryFig. 5.22 Transferring a urogenital specimen toAmies transport medium2. Clean around the urethral opening with sterile saline.3. Apply gentle pressure on the penis so that a drop of pusappears on the meatus; if no pus appears, gently massagethe urethra from above downwards.4. Collect a sample of the pus using a sterile cotton wool swabon a stick (see section 5.4.1). Insert the swab into a smallbottle containing Amies transport medium. Cut the stickto allow the top to be tightened (Fig. 5.22).5. Use another swab to collect a drop of the pus for Gramstaining (see section 5.3.1).From female patientsThe specimen should be taken from the cervical canal by aphysician or specialist nurse. In cases of chronic gonorrhoea,the specimen should be taken just before or just after the menstrualperiod.Preparation of slidesPrepare a smear from each of the specimens. Leave thesmears to air-dry and then stain with Gram stain (see section5.3.1).Fig. 5.23 Gonococci and pus cellsa: Intracellular gonococci; b: extracellulargonococci.5.5.3 Microscopic examinationMicroscopic examination is of great value in the diagnosis ofgonorrhoea in males: it is much less so in females. Culture istherefore necessary to isolate and identify the gonococci inspecimens from females.Examine the slides using the ¥ 100 oil-immersion objective.Pay particular attention to the edges of the smears, where theelements are spread more thinly and are easier to see and thestain is less concentrated.Pus cellsPus cells have a pink nucleus and a colourless cytoplasm. The nucleus may appeardegenerated.GonococciGonococci appear as Gram-negative diplococci (in pairs) (Fig. 5.23 (a)). Cocciappear oval and kidney-shaped. Extracellular Gram-negative diplococci (Fig. 5.23(b)) should also be reported.A presumptive diagnosis of gonorrhoea can be made if Gram-negative intracellulardiplococci are seen in smears from male patients. Extracellular Gram-negative diplococcimay be seen if the pus cells are damaged.Report as:— Gram-negative intracellular diplococci present;— Gram-negative extracellular diplococci present;— no Gram-negative diplococci found.