Laboratory Test Results

1. Laboratory Test Results Brenda C. Barnes and Shawn Froelich

2. Objectives • Correlate urinalysis reagent strip results with microscopic test results. • Correlate microscopic evaluation results of a vaginal swab with clinical symptoms. • Discuss proper collection procedures for anaerobic cultures. • Interpret microbiology susceptibility reports. • Explain the procedure for microscopic examination of skin scrapings. • Describe rapid testing available that is applicable to the clinical setting.

3. Urinalysis

4. Physical Examination of Urine

5. Chemical Examination

6. Chemical Exam – Glucose • Presence of glucose indicates the amount blood glucose has exceeded tubular reabsorptive capacity • Clinical correlation • Diabetes mellitus • Pancreatitis • Hyperthroidism • Gestational diabetes

7. Glucose • Clinitest • Nonspecific test for reducing substances • If performed, done so on pediatric specimens (< 2 years old) • Screening for galactosemia – may be part of state mandated newborn screening program • Microscopic Correlation • No elements seen • Yeast may be present

8. Chemical Exam – Bilirubin • Presence indicates liver disease or biliary obstruction • False-positives due to urine pigments • Ictotest – confirmatory test • Less subject to interference • False-negatives • Age of specimen – bilirubin is unstable • No microscopic correlation

9. Chemical Exam – Ketones • Presence indicates increased fat metabolism • Clinical significance • Diabetic acidosis • Insulin dosage monitoring • Starvation • Malabsorption • Microscopic correlation - none

10. Chemical Exam – Sp. Gravity • Strip reading is adequate for routine screening • Clinical significance • Monitoring patient hydration and dehydration • Loss of renal tubular concentrating ability • Diabetes insipidus • Determination of unsatisfactory specimens • Microscopic correlation – none

11. Chemical Exam – Blood • Presence of red blood cells, hemoglobin, or myoglobin • Hematuria - bleeding • Hemoglobinuria • Lysis of rbc in specimen • Intravascular hemolysis • Myoglobinuria – muscle destruction • Microscopic correlation – rbc seen in hematuria

12. Chemical Exam – pH • Of little diagnostic value – primarily used for determining systemic acid-base disorders • Microscopic correlation – none

13. Chemical Exam – Protein • Presence indicates abnormality in glomerular filtration barrier – renal disease • Correlates with: • Nitrite • Leukocytes • Microscopic

14. Chemical Exam - Urobilinogen • Increased in any condition that causes an increase in production or retention of bilirubin • Clinical significance • Early detection of liver disease • Lever disorders, hepatitis, cirrhosis, carcinoma • Hemolytic disorders • Microscopic correlation – none

15. Chemical Exam – Nitrite • Rapid screening for UTI • Sample needs to be fresh to avoid false-positive reactions • Correlates with: • Protein • Leukocytes • Microscopic

16. Chemical Exam – Leukocytes • Screening test for presence of wbc in urine • Quantification should be done by microscopic examination • Correlates with: • Protein • Nitrite • Microscopic

17. Microscopic Examination • Detect and identify insoluble materials present in urine • Time-consuming = cost • Lacks standardization Protocols used by many labs to improve standardization and cost-effectiveness

18. Rationale – Microscopic Protocol

19. Example Microscopic Protocol

20. Vaginal Swabs

21. Vaginitis • Occurs when the mucosal lining of the vagina becomes inflamed and irritated • Typical signs: • Vaginal discharge • Vulvar itching irritation • Odor • Commonly associated diseases: • Bacterial vaginosis • Trichomoniasis • Candidiasis

22. Laboratory Diagnosis • Vaginal pH • KOH Amine “Whiff” test • Vaginal microscopy (wet mount) • Kit testing • BD Affirm • QuickVue Advance pH an Amines test • QuickVue Advance G. vaginalis test • OsomTrichomonas Rapid Test

23. Sample Collection • Swab vaginal vault and walls with one or two swabs • Include any areas where fluid has pooled • Place swab(s) in test tube containing 0.5 mL saline • Sample should remain at room temperature and tested within two hours of collection http://www.acponline.org/running_practice/mle/wm_exams.htm

24. Vaginal pH • Typical vaginal pH = 4.0-4.5 • > 4.5 • BV • Trichomoniasis • Tested at time of collection

25. Wet Mount • Vigorously mix swab(s) in and out of saline – collect all material adhering to side of tube • Remove swab from saline and depress onto clean, dry microscope slide – express small amount of fluid • Coverslip and examine under microscope http://www.acponline.org/running_practice/mle/wm_exams.htm

26. KOH “Whiff” Test • Prepare wet mount slide as directed, adding one drop of 10% KOH to slide prior to coverslipping • Positive test demonstrates typical “fishy” odor

27. Specimens for Anaerobic Culture

28. Anaerobic Specimens • Most anaerobic infections are caused by endogenous microbiota • Improper collection may result in the growth of many anaerobes, resulting in difficulty to determine the cause of infection • Labs follow criteria for rejection of inappropriately collected and/or transported specimens

29. Acceptable Specimens for Anaerobic Culture • Aspirated material • CSF, blood, bone marrow, synovial fluid • Aspiration of closed abscess, ascites fluid, peritoneal fluid • Deep tissue or bone biopsy • Aspirated pus from decubitus ulcers • Suprapubic bladder aspiration • Pleural fluid obtained by thoracentesis, open lung biopsy, “sulfur granules” from draining fistula

30. Unacceptable Specimens for Anaerobic Culture • Swabs • Throat, nasopharyngeal, gingival, rectal, vaginal, cervical, urethral, surface wounds and abscesses • Expectorated or suctioned sputum, bronchial washings • Contents of large bowel, feces, colostomy effluents, gastric and small bowel contents • Voided or catheterized urine

31. Transport and Processing of Anaerobic Specimens • Transport and processing should be quick to maintain temperature, avoid exposure to oxygen and avoid dessication • Oxygen-free transport tubes/vials such as PRAS media (prereduced, anaerobically sterilized) • Anaerobic bags or pouches if delays in transport • Blood cultures require aseptic collection with bactericidal agent such as tincture of iodine or chlorhexidinegluconate with 70% alcohol to minimize contamination with normal skin biota