Diagnostic Microbiology


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Diagnostic Microbiology Organization


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Basic Organization diagnostic microbiology Laboratory:

Dr.T.V.Rao MD Basic Organization diagnostic microbiology Laboratory 10/13/2012 Dr.T.V.Rao MD 1

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The work environment has changed with the development of new technology. Laboratories have always seen the need for change and development, there has been increased pressure to improve performance, tighten margins, improve quality and reduce costs Challenges in Diagnostic Laboratories 10/13/2012 Dr.T.V.Rao MD 2

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Medical Laboratory Managers Each laboratory must have a strategic plan that describes its long-term goals, such as a move toward more automation or molecular diagnostic techniques. Each employee’s role should be clearly defined, and written job descriptions should be provided so personnel know what they are expected to do. Therefore, it is a not an easy task for a manger to strike a balance among the clinical laboratory regulations, fiscal responsibility, and employee competence and morale to maintain the overall quality of patient care. 10/13/2012 Dr.T.V.Rao MD 3

The laboratories should faction from sense to common sense:

I t is appropriate to remember that the two most important components of management are C ommon sense O pen communication with laboratory staff The laboratories should faction from sense to common sense 10/13/2012 Dr.T.V.Rao MD 4

Microbiology Laboratory:

Microbiology Laboratory Clinical Microbiology comprises essentially seven sections. Aerobic and anaerobic bacteriology Mycology Mycobacteriology (also called Acid-fast Bacteriology, AFB) Parasitology Virology Serology Molecular diagnostics (PCR & DNA probe technology) : 10/13/2012 Dr.T.V.Rao MD 5

Plan for the division of microbiology:

Sample Receiving & Processing Section Samples brought to the clinical microbiology are at first received by this section. Here sample are received and the samples are processed according to the nature of the sample. Urinalysis Section In this section detailed report of urine samples including physical, chemical, microscopic examination is be prepared. Plan for the division of microbiology 10/13/2012 Dr.T.V.Rao MD 6

Division of parasitology:

Parasitology Section Parasitology section deals with intestinal parasites. Samples of faeces are examined here for the presence of any intestinal parasite. Slides are prepared here inside a safety cabinet. Division of parasitology 10/13/2012 Dr.T.V.Rao MD 7

Bacteriology Cultures main part of Laboratory services :

Nose, Throat,  Sputum and Urogenital Cultures and Sensitivity Section Here cultures of respiratory tract and genital tract infections are prepared. Blood cultures, Wounds Culture and Sensitivity Section Culture of wound swab, pus, aspirates, body fluids including CSF are the responsibility of this section. Bacteriology Cultures main part of Laboratory services 10/13/2012 Dr.T.V.Rao MD 8

Bacteriological cultures is the major gratifying work :

Urine Culture & Sensitivity Section Different types of urine culture performed here including mid stream urine and catheter samples of urine. Each sample is processed and evaluated accordingly. Blood Culture and Sensitivity Section In this section culturing of blood samples is carried out. Nowadays, this section is equipped by machines such as Bactec 9240, flourometric instruments. Each instrument is capable of running 240 samples at a time. Bacteriological cultures is the major gratifying work 10/13/2012 Dr.T.V.Rao MD 9

Serology Section:

Serology Section In serology section immunological and serological tests are performed by different techniques like Latex agglutination, haemagglutination and antibody absorption. Serology Section 10/13/2012 Dr.T.V.Rao MD 10

Mycobacteriology :

Mycobacteriology Culture & Sensitivity Section In this section all TB smear, culture and sensitivity performed in two Biosafety II and III cabinets to avoid risk of infection Mycobacteriology 10/13/2012 Dr.T.V.Rao MD 11

Mycology laboratory services an emerging need:

Mycology Culture Section Requests for fungus smear and culture processed here in a bio safety II cabinet to avoid infection from fungal spore. Regardless of the organisation of a Microbiology Laboratory, the main aim is providing the client (the physician) with accurate and reliable results to assist the process of clinical treatment. Mycology laboratory services an emerging need 10/13/2012 Dr.T.V.Rao MD 12

Quality control in microbiology laboratory:

Quality Control Section In this section quality control of water, food products and environment is performed with the help of different media and colony counters. Quality control in microbiology laboratory 10/13/2012 Dr.T.V.Rao MD 13

Managing the sample: technical:

Managing the sample: technical Macroscopic evaluation Split sample for different laboratory disciplines Two possible approaches: perform only those tests requested by sender perform diagnostics for syndromes/clinical description (laboratory initiative) Storage of samples refrigerator or freezer 10/13/2012 Dr.T.V.Rao MD 14

Direct methods:

Direct methods Macroscopic evaluation Direct microscopy Electron microscopy Staining Rapid tests Molecular methods Propagate the agent No propagation required 10/13/2012 Dr.T.V.Rao MD 15

Macroscopic evaluation an example:

Consistency rice water stools for Cholera Blood Visible parasites Helminths segments Macroscopic evaluation an example 10/13/2012 Dr.T.V.Rao MD 16

Direct microscopy :

Direct microscopy Wet mount technique hanging drop Dark background microscope fragile organisms (e.g. spirochetes) Viability maintained mobility may be observed Observations white blood cells (denotes invasion) red blood cells parasites protozoa Helminths eggs moving bacteria 10/13/2012 Dr.T.V.Rao MD 17


Staining A specific staining Gram staining Specific staining with chemicals Ziehl Neelsen staining (Mycobacteria) Modified Ziehl Neelsen staining (Cryptosporidium) Specific staining with labelled antibodies Immunofluorescence - used when gram stain cannot help in diagnosis (e.g. Legionella too small to be visible in a Gram stain) 10/13/2012 Dr.T.V.Rao MD 18

Rapid tests:

Rapid tests Goals bacterial, viral or parasite antigen (surface antigen, soluble antigen) toxin in biological fluids (e.g. cerebrospinal fluid, blood, urine) Main techniques direct agglutination: slides, cards latex agglutination: slides, cards immuno-chromatography: dipsticks 10/13/2012 Dr.T.V.Rao MD 19

. Direct Methods - propagation required:

. Direct Methods - propagation required Bacteriology and mycology most agents can be propagated on culture media Virology most agents can be propagated on cells Parasitology monocellular organisms can be propagated in culture media 10/13/2012 Dr.T.V.Rao MD 20


Personnel The following directorial functions are : 1- interpretation , correlation , and communication of lab data 2- interaction with physicians and/or medical staff , patient , administration . 3- monitoring of standard of performance , QC , QI. 4- provision of education programs , planning , research. 5- ensuring sufficient personnel with adequate documented training and experience to meet the needs of the lab . 6- he/she must be decision-maker in the selection of all lab equipment's and supplies . 10/13/2012 Dr.T.V.Rao MD 21

Propagation: advantages/disadvantages :

Propagation: advantages/disadvantages Advantages allows anti-microbial susceptibility testing allows typing of the micro-organism allows storage of the strain Disadvantages depends upon the viability/condition of the agent takes time 10/13/2012 Dr.T.V.Rao MD 22

Detecting antibodies:

Detecting antibodies Precipitation Agglutination Haemagglutination and haemagglutination inhibition Viral neutralization test Radio-immunoassays ELISA Immunofluorescence Immmunoblotting Immunochromatographic 10/13/2012 Dr.T.V.Rao MD 23

Antibody detection: advantages/disadvantages:

Antibody detection: advantages/disadvantages Advantages inexpensive easy to perform allows identification of IgM (acute infection) IgG (past infection) Disadvantages delayed response (false negative results during sero-conversion window) time of infection not always clear 10/13/2012 Dr.T.V.Rao MD 24

Standards and Checklists:

Standards and Checklists Purposes: Standards are the broad principles the laboratory must meet in order to achieve accreditation Checklists provide detailed requirements that inspectors use to determine whether laboratories meet the Standards 10/13/2012 Dr.T.V.Rao MD 25

Laboratory Inspections: Maintaining Balance:

Laboratory Inspections: Maintaining Balance Quality Improvement Education Regulatory Compliance 10/13/2012 Dr.T.V.Rao MD 26

The Standards for Laboratory Accreditation:

The Standards for Laboratory Accreditation Standard I Director / Head of the Divison Standard II Physical Facilities & Safety Standard III Quality Control and Performance Improvement Standard IV Inspection Requirements 10/13/2012 Dr.T.V.Rao MD 27


Checklists Guide the inspection by assisting with the interpretation of desired Standards Provide guidelines for development of laboratory policies, procedures and processes Help ensure accurate, reliable test results Ensure a focus on patient safety 10/13/2012 Dr.T.V.Rao MD 28

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The QC / QI program should be clearly defined and well-organized. The QI program must provide the system design and evaluation of proper patient identification and preparation ; specimen collection ; preservation ; transportation ; storage before testing ; processing ; and accurate results reporting. This system must ensure optimum patient specimen and integrity of the result throughout the pre-analytical , analytical , and post-analytical process. Quality control and Quality improvement 10/13/2012 Dr.T.V.Rao MD 29

QI / QA “supervision:

” Judgment of the acceptability of QC data must be made at least monthly by the lab director . Because of many variables , the CAP makes no specific recommendations on the frequency of any additional assessment / review of QC data . There must be evidence of active review of records of instrument function , temp , and maintenance , for all routine procedures on all shifts. QI / QA “ supervision 10/13/2012 Dr.T.V.Rao MD 30


The lab must have documented system in operation to detect and correct significant clerical and analytical errors. One common method is review of results by a qualified person before release from the lab , but there is no requirement for supervisory review of all reported data. The selective use of delta checks also may be useful in detecting clerical errors in consecutive samples from the same patient. In computerized lab , there should be automatic alarm for improbable results. QI / QA “ SUPERVISION” 10/13/2012 Dr.T.V.Rao MD 31

Effects of Pre-analytical Variables On the Quality of Laboratory Testing :

Effects of Pre-analytical Variables On the Quality of Laboratory Testing Modern laboratories around the world are now enjoying the benefit of decades of development in technology “ State of the Art " instrumentation are common in most laboratories Walkway , high throughput analyzers are employed for routine and specialized testing 10/13/2012 Dr.T.V.Rao MD 32

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Programme Created by Dr.T.V.Rao MD for Medical Microbiologists Email doctortvrao@gmail.com 10/13/2012 Dr.T.V.Rao MD 33

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