summary of the diagnostic value of specific microbiological investigations
DESCRIPTION
Summary of the diagnostic value of specific microbiological investigations. Blood culture. Technique Minimal 1~3 mL each Different venipuncture ( ≥ 2 sets) Central catheter + Peripheral culture Colonized bacteria – possibility of contamination. Blood culture. Blood culture. Gram stain. - PowerPoint PPT PresentationTRANSCRIPT
Summary of the diagnostic value of specific microbiological investi-
gations
Test Diagnostic value
False posi-tive rate
False nega-tive rate
Blood culture ++++ - +++ Viral antigen detection (nasopharyngeal aspirate) +++ - +
Viral culture +++ - ++ Serum antigen ++ + ++ Urine antigen + ++ ++ Paired antibody titre +++ + ++ Bacterial culture of na-sopharyngeal secretions
- +++ +
Lung puncture culture ++++ - +
Blood culture• Technique
– Minimal 1~3 mL each– Different venipuncture (≥2 sets)– Central catheter + Peripheral culture
• Colonized bacteria – possibility of contami-nation
Blood culture
Blood culture
Gram stain
Interpretation of blood culture• Almost always
important– S. aureus– S. pneumoniae– S. pyogenes (GAS)– S. agalactiae (GBS)– H. influenzae– Enterobacteriaceae
(E. coli, Klebsiella, etc..)– Bacteroidaceae– P. aeruginosa– Candida species
• Possible contaminant– P. acnes– Corynebacterium species– Bacillus species– CoNS (coagulase negative
Staphylococci, S. epider-midis)
– S. viridans– Peptostreptococcus
Most causative pathogens are compatible with clinical syn-drome
Most causative pathogens will grow within 72 hours
Nasopharyngeal aspirate collection
• Nasopharyngeal aspirate – Virus culture / PCR
Early diagnosis of viral infection
Microscopy – LM– EM
Detecting antigen– IF staining– Solid phase immunoassay (ELISA, RIA, LA), – Immunochromatography
Detecting nucleic acid– nucleic acid amplification (PCR, etc.), – nucleic acid hybridization
Tzank test of HSV Vesicular Lesion
Ultrastructural Characteristics of SARS-Asso-ciated Coronavirus Grown in Vero E6 Cell
100 nm
Indirect Immunofluorescent staining
Immunofluorescent staining
• Indirect IF Staining for RSV, • Specimen: Nasal aspirate
• Indirect IF Staining for PIV3 • Specimen: Nasal aspirate• Confocal microscopy
Antigen Detec-tion
by ELISA
Direct Method
Indirect Method
Indirect ELISA for RSVSpecimen: Nasal aspi-rate
Immunochromatography
Conventional method vs. RT-PCR
Virus identified No. detected by RT-PCR(% of total episodes)
Respiratory syncytial virus 122 (23.7) 596 (14.7)Adenovirus 35 (6.8) 243 (6.0)Parainfluenza virus type1 11 (2.1) 30 (0.7)
type 2 ND 23 (0.6)
type 3 32 (6.2) 195 (4.8)
type 4 ND 2 (0.05)Influenza virus A 24 (4.7) 117 (2.9)
B 9 (1.8) 47 (1.2)
Total 316 (61.4) *
*More than 1 virus were isolated from 36 patients (11.4%) among 514 patients, Sep 2000-Aug 2005.**1,270 strains of viruses were isolated from 1,234 out of 4,058 cases (30.4% of total patients), Nov 1990-May 2002. More than 1 virus were isolated from 36 patients.
Detection by conventional method (% of total episodes)
1,270 (30.4) **
RhinovirusMetapneumovirusCoronavirus, conventionalCoronavirus NL63BocavirusUnknown
40 (7.8)26 (5.0) 1 (<1) 9 (1.8)58 (11.2)
ND ND ND ND ND 17 (0.3)
Choi EH et al. Clin Infect Dis 2006;43:585-92