ROLE OF CLINICIAN IN LAB.DIAGN

Clinical diagnosis – how microbiology can help or complicate it An infectious diseases perspective : 

Clinical diagnosis – how microbiology can help or complicate it An infectious diseases perspective Václav Chmelík Nemocnice Ceské Budejovice a.s., JCU ZSF Praha, June 12, 2008

1968The war against infections has been definitely won ! US Surgeon General 2001 Swimming in the ocean of microbes… Motto of an exhibition in Natural History Museum NY : 

1968The war against infections has been definitely won ! US Surgeon General 2001 Swimming in the ocean of microbes… Motto of an exhibition in Natural History Museum NY

CHANGING INFECTIONSOR CHANGING OPINION? : 

CHANGING INFECTIONSOR CHANGING OPINION?

Changing infections in a changing world : 

Changing infections in a changing world Incidence: immunity: vaccination, individual and herd im. microbe: new manifestations of older m. microbial evolution lifestyle: nutrition behaviour (IVDU) sexual revolution medicine: invasivity chemotherapy, immunosupression hospital ecology import : transportation, tourism, migration war, natural disasters, bio terrorism, bio warfare

Changing infections in a changing world : 

Changing infections in a changing world Patients : demographic features increasing life expectancy surviving severe illnesses, co-morbidities immunity prosthetic material Changing clinical picture Changing therapeutic tools availability and misuse of medicines antibiotic resistance side effects

Main problems : today and tomorrow : 

Main problems : today and tomorrow Polymorbid patient with superposed infection Transplant patient : organ bone marrow Patient with prosthetic material Immunosupressed patient, corticosteroid therapy biologic therapy Elderly patient Metabolic syndrome COMPLEX MANAGEMENT IS ESSENTIAL !! Import of dangerous endemic infection Pandemic caused by new virus (influenza?) AWARENESS!! PREPARDENESS !!

DIAGNOSIS OF INFECTION? : 

DIAGNOSIS OF INFECTION?

Development of diagnosis : 

Development of diagnosis Continual/discontinual process „drawing near truth“ (limited, changing situation) Results, new data arrive continually Diagnostic „forward leap“: after receiving and accepting certain amount of data Therapeutic action: is our goal! is outcome always a proof of correct presumption? may also conceal other important information !!

Phase (stage) of diagnostic process: : 

Phase (stage) of diagnostic process: 1. Where are we? 2. New data: arriving weighting accepting or refusing incorporating into system 3. Interim diagnosis 4. New questions (indication of new tests) 5. Therapeutic action?

Diagnosis of infection : 

Diagnosis of infection Syndrome – involved organs and systems Aetiology Severity of illness Age Co-morbidities Disease characteristics: Focal infection? Sepsis? Severe sepsis? Acute illness? Exacerbation of chronic disease?

Knowledge of causative pathogen : 

Knowledge of causative pathogen Epidemiology Targeted anti-infective therapy Antibiotic therapy : empiric presumptive targeted effectiveness spectrum ecology price

Infection treatment : 

Infection treatment Basics: Nutrition, hydration Physiological functions Hygienic standard: skin, mucosa Physical therapy Mental status Anti-infective chemotherapy Symptomatic pain control fluid and electrolyte balance vital functions support Surgery

Indication and performance of laboratory test : 

Indication and performance of laboratory test

Examination is like a reflex arc : 

Examination is like a reflex arc Efferent arm Clinician Result Request form Sample LAB Afferent arm

Examination is like asking a question : 

Examination is like asking a question Indication of examination = asking a specific question Performing the examination: information technology economy Phases of lab examination : preanalytic analytic postanalytic

Examination and errors : 

Clinic . transport Clinical interpretation Application Indication Interpretation Sampling Examination ( dif.dg.?) Request Sample form transport Reception LAB Examination and errors PATIENT Result

Question and sampling : 

Question and sampling History, obligatory information Unecquivocal description of the problem Communication with lab : request form information network dialogue (personal, phone, e-mail) Sampling: who, how? preparation, collection, request form Transport of material: timing, temperature, damage

Value of laboratory result : 

Value of laboratory result a/ good laboratory practice b/ clinical point of view: intelligibility clinical application patient‘s profit Lab practice Result Practical value good valid essential good valid useful good valid abundant good valid confusing good valid harmful

Krejcarek syndrome : 

Krejcarek syndrome Young corpulent lady Pink-cheeked Sitting on her bed Gorging on a knackwurst* Weeping: „ I am OK! I want to go home!“ One abnormal lab result Krejcarek syndrome is not an indication for administration of high - dosed antimicrobials ! ! !

Value of lab result : 

Value of lab result Capability of the method to solve our problem value, worth of method Patient‘s status Value of material: - patient‘s discomfort and/or risk of sampling - impossibility to repeat sampling Physician‘s competence Legal consequences

Aliquotation /archivation of material : 

Aliquotation /archivation of material Sampling of valuable material Storage of aliquots for further examination (frozen serum/ material, cytology, histology) Further tests indicated due to: clinical status change need of confirmation new diagnostic methods new diseases Re-evaluation

V. I. M. ( very important material ) : 

V. I. M. ( very important material ) Pus from: joint peritoneal/ pleural cavity deep abscess (organ, muscle) brain /epidural abscess CSF CV catheter Blood culture Septic prosthetic material Other material (important from clinical point of view)

Main problem : 

Main problem Is the identified bug ( its antigen, DNA/RNA, antibody ) really causing the disease? Incorrect sampling Colonising flora Contamination during transport Mistaken identity of material Contamination in lab How to recognize it? INTERPRETATION - DIALOGUE - COOPERATION

Molecular biologic methods : 

Molecular biologic methods Advantages: rapidity sensitivity detectability in patient treated with antimicrobials Disadvantages : sensitivity easy contamination clinician‘s faith in / relying on hi-tech method All results have to be interpreted !

Validity of molecular test : 

Validity of molecular test Value of extrahuman genome detection? Obligatory pathogen (never present in healthy human) ++ Microbial NA obtained from body site: super sterile (CSF, prosthesis) + with transient presence of bacteria ?? colonised (pharynx, colon) ???? genomics- prteonomics – pathogenesis –manifestation

Introduction of a new method : 

Introduction of a new method Clinician has to know (before introducing the method): principle of the method (basic knowledge) which question is solved sensitivity - specificity comparability with older used method comparability with other labs („in house“ ?) The worst message: „They‘ve done something that I don‘t understand at all !!!

Proven diagnosis? : 

Proven diagnosis? Problem: „Case definition“ – are our diagnoses well defined? Which methods have to be used (and their results) for: proven diagnosis probable possible

In cauda venenum : 

In cauda venenum Not managing a single organ Not treating a germ, its name, antibodies or nucleic acid Managing ill human being! A lot of infective complications (especially in elderly patients) are due to non infective reasons! A lot of symptoms may be resolved without antibiotics Even well managed surgery and targeted ATB therapy without appropriate nutrition, fluid and electrolyte balance, care and treatment of co-morbidities will fail

Thank you : 

Thank you