• 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
laboratory diagnosis of infectious
diseases
• Bacteriologic
• Immunologic(serologic)
• Molecular (nucleic acid–based) tests
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
MICROBIOLOGICAL DIAGNOSIS
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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 floraselective media to supress the growth of
commensal organisms
MICROBIOLOGICAL DIAGNOSIS
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Specimen choice
Apropriate specimens
Containers –labelled sterile containers
Transport –
Specimen quality control –result depend on
quality of specimen
• Identify unsatisfactory specimens
MICROBIOLOGICAL DIAGNOSISLAB EXAM
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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
MICROBIOLOGICAL DIAGNOSISLAB EXAM
• Culture on solid media –isolated colonies for
identification & susceptibility testing
• Media for bacterial culture
• Serology & antigen detection –rapid diagnosis,
organisms difficult to culture
HAZARDS IN PATH LABS
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unsafe premises
Naked flames
Chemical hazards
Glassware hazards
Equipment hazards
Explosions
Microbial hazards
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
BIOHAZARDS IN PATH LABS
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Inhalation –
Infected airborne droplets
Infection of general public –
Escape of microorganisms during transport,
improper disposal of infectious waste
Classificaton of infective
microorganisms
• Risk group 1 –
• Low risk to lab worker & members of
community eg . Food spoilage bacteria, yeasts,
common moulds
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
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
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
SAFE LAB PRACTICES
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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
SAFE LAB PRACTICES
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SAFE WORKING PRACTICESPersonal 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,
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
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
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.
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
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.
LAB INFECTIONS - TYPES OF
ACCIDENTS
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Splashes & sprays
Needlesticks, sharp objects,
Mouth pipetting
Animal bite or scratch
MICROBIOLOGY
• Five basic techniques in microbiology –five I,s
• Inoculation, incubation, isolation, inspection,
identification