Microbiologic sampling

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Microbiologic sampling Laboratory

Transcript of Microbiologic sampling

  • 1. Iman M. Fawzy Clinical Pathology MD. PhD Mansoura, Egypt
  • 2. SamplingSampling inin MicrobiologyMicrobiology Iman M. Fawzy Clinical Pathology MD. PhD Mansoura, Egypt
  • 3. The best use of microbiologic lab. involves sending only relevant specimens. For obtaining good quality sample for microbiologic examination, certain precautions should be considered.
  • 4. Rapid transporting of the specimens to the lab. Collection of specimens before antibiotic therapy. Sample collection as early as possible in the disease. Containers used for collection should be sterile, tightly capped, and clearly labeled. Cleaning the site of infection General precautionsGeneral precautionsGeneral precautionsGeneral precautions
  • 5. Any specimen should be accompanied by request containing: Patient's name, age, gender, in or outpatient, ward number, home area . Type & source of specimen, date & time of collection. Investigation(s) required. Clinical note summarizing the patient's illness, suspected diagnosis, antimicrobial therapy. Name of clinical officer . Request formRequest formRequest formRequest form
  • 6. Proper Sampling in Clinical Microbiology Laboratory Collection of good quality specimens Depends on: 1. The optimal time of specimen collection . 2. The correct type of specimen 3. Well collected specimens with minimum contamination from normal flora of the patient or the person collecting the specimen. 4. Adequate amounts of each specimens and appropriate no. of specimens 5. Clearly labeled safe specimens Proper SamplingProper SamplingProper SamplingProper Sampling
  • 7. Proper SamplingProper SamplingProper SamplingProper Sampling 1-Optimal time of collection of specimens: 1-Optimal time of collection of specimens: Specimens for the culture of bacteria must be collected before the start of antibiotics Blood films for malarial parasites are usually best collected just as the patient's temperature starts to rise When infective endocarditis is suspected, three blood culture sets can be collected within a 24 h period irrespective of the temperature of the patient .
  • 8. Proper SamplingProper SamplingProper SamplingProper Sampling 1-Optimal time of collection of specimens: 1-Optimal time of collection of specimens: Serology is usually most satisfactory when a fourfold or greater rising antibody titre to a pathogen can be demonstrated in paired sera. Specimens for electron microscopy or isolation of viruses are most likely to give positive results when collected during the most acute stages of the disease
  • 9. Proper SamplingProper SamplingProper SamplingProper Sampling 2-Correct types of specimens 2-Correct types of specimens Patients with possible bacterial meningitis should have blood cultures as well as cerebrospinal fluid collected. Cervical, urethral and preferably rectal swabs should be collected rather than high vaginal swabs from female patients with suspected gonorrhoea. Pernasal swabs should always be collected from children who may have pertussis rather than a throat or ordinary nose swab.
  • 10. Proper SamplingProper SamplingProper SamplingProper Sampling 3- Well- collected specimens with minimal contamination from normal flora 3- Well- collected specimens with minimal contamination from normal flora All staff should become aware of the importance of minimizing the contamination of specimens. Poor-quality specimens include saliva instead of sputum or a salivary-mucoid sputum sample instead of a mucopurulent specimen from a patient with pneumonia . Mid-stream specimens of urine to avoid excessive contamination.
  • 11. Proper SamplingProper SamplingProper SamplingProper Sampling 3- Well- collected specimens with minimal contamination from normal flora 3- Well- collected specimens with minimal contamination from normal flora Throat swab collected should not touch the buccal mucosa or tongue . A high vaginal swab should be collected using a vaginal speculum which should not be wet with antiseptic solution with care not to touch the lower region or perineum. Blood or cerebrospinal fluid (CSF) cultures can be contaminated by the skin flora of the patient or from the doctor .
  • 12. Proper SamplingProper SamplingProper SamplingProper Sampling 4-Adequate quantity of the specimens 4-Adequate quantity of the specimens The collection of adequate quantities of early morning sputum. At least two samples of faeces on different days are desirable from patients with diarrhoea. When carriage of Salmonella typhi is investigated in a food handler, 6 samples of faces should be cultured.
  • 13. Proper SamplingProper SamplingProper SamplingProper Sampling 4-Adequate quantity of the specimens 4-Adequate quantity of the specimens Patients with diarrhea at least 2 specimens of faces is collected for culture of Salmonellae or Shigella. Serological investigations usually require paired sera.
  • 14. Proper SamplingProper SamplingProper SamplingProper Sampling 5-Clearly labeled and safe containers 5-Clearly labeled and safe containers Microbiological investigations should be placed in leak- proof containers. Each container should be enclosed in a plastic bag. Examples of microbiological hazards to staff handling leaking containers include TB, and viruses such as HBV and HIV.
  • 15. Urine SamplesUrine Samples Morning sample. Washing the site with soap & water 3 times, and in female from front to backward. Mid stream sample for routine culture & 24h (3 times) for T.B. In children: Suprapubic aspiration Adhesive bag
  • 16. Urine SamplesUrine Samples If the patients is already catheterized, catheter sample can be used. Sterile, dry, wide-necked, leak proof container is used. Collection of 10 20 ml urine. To preserve the sample, (0.Ig /10ml urine) boric acid is used.
  • 17. Urine SamplesUrine Samples When gonorrhea is suspected immediate culture (bed side) or using transport medium
  • 18. Blood SamplesBlood Samples During peak of fever. Sterilizing the site of venipuncture with alcohol 70% & iodine . Samples for aerobic blood culture are collected in the green capped bottles, while those for anaerobic blood culture are collected in the red capped bottles.
  • 19. Blood SamplesBlood Samples For adults at least, 5mL of blood are collected while for infants and children 2mL of blood only are collected. For automated blood culture system special bottles are used. Blood is introduced through the rubber cap.
  • 20. Blood SamplesBlood Samples Serum can be used for culture on fluid medium. Blood for serological diagnosis is collected in screw capped tubes without anticoagulant.
  • 21. Body Fluids SamplesBody Fluids Samples Sterilizing the site with alcohol 70% and iodine. Rapid transporting to the lab especially for CSF. Using wide mouth, sterile containers to which 0.3ml of 20% Na citrate is added to prevent clot formation.
  • 22. Sputum SamplesSputum Samples Morning sample. Washing the mouth with water and brushing the teeth. Sputum rather than saliva . In infants, gastric lavage can be used.
  • 23. Sputum SamplesSputum Samples An alternative method, the tongue is depressed and cough is induced by touching the larynx, material from the trachea expelled during the cough will adhere on the swab. Samples for T.B. are 3 consecutive morning samples.
  • 24. SwabsSwabs It is a sample device consist of sterile pledget of absorbent material, usually cotton-wool or synthetic fiber, mounted on a thin wire or stick. Swabs for Bacterial (red) and Viral (green) Cultures
  • 25. SwabsSwabs The absorbent material may be inhibitory to the pathogens, some swabs may be treated to prevent inhibitory effect: Boiling the swab in phosphate buffer Coating the swab with serum Or coating the swab with albumin or charcoal
  • 26. SwabsSwabs Us