laboratory diagnosis of infectious diseases

1. A Great Islamic scolar ,Ibn-al Qayyaum R.A said: the things that make the body sick are: Too much! talking, Too much sleeping, Too much Eating

2. laboratory diagnosis of infectious diseases • Bacteriologic • Immunologic(serologic) • Molecular (nucleic acid–based) tests

3. Koch,s postulates • Organism must be present in lesions in every case of disease • Possible to isolate org in pure culture • Inoculation of pure culture in lab animal should produce disease • Possible to reisolate the org

4. MICROBIOLOGICAL DIAGNOSIS • Multi-step process • Clinician- patient meeting • Specimens – quality of specimens is crucial • Specimen from sterile sites- enrichment media • Specmen from a site with a normal flora- selective media to supress the growth of commensal organisms

5. MICROBIOLOGICAL DIAGNOSIS • Specimen choice • Apropriate specimens • Containers –labelled sterile containers • Transport – • Specimen quality control –result depend on quality of specimen • Identify unsatisfactory specimens

6. MICROBIOLOGICAL DIAGNOSIS-LAB EXAM • Direct exam – • Microscopy –rapid presumptive diagnosis • Saline wet preparation of stool • Gram,s stain, Ziehl-Neelsen stain, Leishman,s stain, • Culture –amplification in number of pathogens, • Selective media –discrimination between pathogens & non-pathogens

7. MICROBIOLOGICAL DIAGNOSIS-LAB EXAM • Culture on solid media –isolated colonies for identification & susceptibility testing • Media for bacterial culture • Serology & antigen detection –rapid diagnosis, organisms difficult to culture

8. HAZARDS IN PATH LABS • unsafe premises • Naked flames • Chemical hazards • Glassware hazards • Equipment hazards • Explosions • Microbial hazards

9. BIOHAZARDS IN PATH LABS • Ingestion – • Contaminted fingers, mouth pipettting,eating food in lab, • Inoculation – • Needlestick injuries , injury from broken contaminated glassware, open uncovered skin wound

10. BIOHAZARDS IN PATH LABS • Inhalation – • Infected airborne droplets • Infection of general public – • Escape of microorganisms during transport, improper disposal of infectious waste

11. Classificaton of infective microorganisms • Risk group 1 – • Low risk to lab worker & members of community eg . Food spoilage bacteria, yeasts, common moulds

12. Classificaton of infective microorganisms • Risk group 2 – • moderate risk to lab worker & limited risk to members of community, • Can cause serious human disease • Staphylococci, streptococci, enterobacteria, clostridia, vibrio, adenovirus, poliovirus, hepatitis viruses, toxoplasma, leishmania

13. Classificaton of infective microorganisms • Risk group 3 – • High risk to lab worker & low risk to members of community, • Can cause serious human disease • Brucella spp, Mycobacterium tuberculosis, S. typhi,francisella, arboviruses, LCM virus, rickettsiae, chlamydia, coccidioides, histoplasma, HIV

14. Classificaton of infective microorganisms • Risk group 4 – • High risk to lab worker & to members of community, • Can cause serious human disease & readily transmitted from one person to another • Viruses of haemorrhagic fevers, Marburg, Lassa, Ebola

15. SAFE LAB PRACTICES • Safe working environment – • Display safety signs & notices • Keep lab clean • Separate & dispose waste • Decontamination procedures • Disinfectants & their use in lab • Sterilization • Regulations for safe packaging & transport of specimens • Reporting of faults

16. SAFE LAB PRACTICES • SAFE WORKING PRACTICES- • Personal hygiene • Protective clothing • Preventing lab acquired infections • Handling of spillage of a specimen • Working tidily, use of racks, • Use of protective gloves, goggles, face shield, dust mask,

17. DUTIES OF LAB SAFETY OFFICER • Monitor safety reg in lab • Staff taught to handle fire, equipment fault, specimen or chemical spillage • Test methods are safe • No mouth pipetting • Use of protective clothing in lab • No smoking, eating, drinking, applying cosmetics

18. DUTIES OF LAB SAFETY OFFICER • maintenance of first aid box, eye wash bottles, fire extinguishers • Cleanliness of lab, benches free of books & personal property • Maintenance of equipment • Observe safety reg regarding pts & visitors to lab are followed • Check structural defects in lab • Review & discuss safety reg with staff

19. UNIVERSAL PRECAUTIONS • Blood & certain body fluids ( amniotic fluid, CSF, pleural fluid, peritoneal fluid, pericardial fluid, semen, vaginal secretions, any fluid visibly contaminated with blood ) of all patients are potentially infective.

20. UNIVERSAL PRECAUTIONS • Hand washing before & after all patient contact • Use of gloves if soiling of hands with blood is likely • Gowns should be worn if soiling of skin or clothing is likely • Mask • Protective eyewear • Private room for patient if hygienic practices are poor

21. UNIVERSAL PRECAUTIONS • Proper disposal of contaminated needles/sharps in puncture resistant containers • No resheathing/recapping of used needles • Spills of blood – cleaned with 1:10 dil of bleach • Barrier precautions ( masks, protective eyewear, gowns ) indicated, when splashes are expected to be generated.

22. LAB INFECTIONS - TYPES OF ACCIDENTS • Splashes & sprays • Needlesticks, sharp objects, • Mouth pipetting • Animal bite or scratch

23. MICROBIOLOGY • Five basic techniques in microbiology –five I,s • Inoculation, incubation, isolation, inspection, identification