1

THE GRAM STAINADVANCED INTERPRETATIONS

Richard (Tom) Thomson, Jr., Ph.D.Northwestern University Feinberg School

of MedicineEvanston Northwestern Healthcare

1

REVIEW OF THE BASICS

• Procedural highlights– Select area of specimen– Prepare smear– Low and high power scanning– Quantitate cells and microorganisms– Interpret by specimen source– Slides for review

• Interpret bacterial morphologies– Minimum competency– Advanced competency

2

EXTRA GRAM STAIN MORPHOLOGIESINDICATORS OF PATHOLOGY

• White blood cells (polymorphonuclear leukocytes)

• Alveolar macrophages• Squamous/columnar epithelial

cells• Elastin/collagen fibers• Curschmann’s spirals• Corpora amylacea

3

EXTRA GRAM STAIN MORPHOLOGIESINDICATORS OF PATHOLOGY

• Cell necrosis • Intracellular bacteria/yeasts• “Antibiotic” treated bacteria• Crystals• Respiratory therapy• Other oddities

4

5 6

2

7 8

9 10

11 12

3

13 14

15 16

17 18

4

19 20

21 22

23 24

5

25 26

27 28

29

GRAM STAIN: PATTERN RECOGNITION

• Respiratory tract– Pneumonia/bronchitis– Aspiration pneumonia– Cystic fibrosis– Chronic lung disease/COPD

• Urinary tract– UTI– Vesicocolonic fistual

• Meningitis

30

6

GRAM STAIN: PATTERN RECOGNITION

• Abscess– Staphylococcal– Mixed aerobic/anaerobic– Streptococcus milleri/anginosis– Nocardia

• Toxemia– Streptococcal necortizing fasciitis– Clostridium gas gangrene

• Miscellaneous– BV (bacterial vaginosis)– Lemierre’s disease (jugular vein thrombosis)– Gonococcal urethritis– Crystalline joint disease

31 32

33 34

35 36

7

37 38

39 40

41 42

8

43 44

45 46

47 48

9

49 50

51 52

53 54

10

55

56

AFTER ALL THIS TRAINING

• Can you identify the pathogen in the following case?– Newborn sepsis– Mother appears at hospital in labor

• no pre-natal care

– Peri-partum fever– Child delivered vaginally

• Blood and CSF specimens for stain/culture

57 58

59

CONCLUSIONSMicrobiology Model

• Standardize Gram stain procedure• Minimum competency for laboratory personnel• Gram stain review procedure• Advanced interpretation

– Indicators of pathology– Pattern recognition (diseases)

• Use Gram stain results in culture work-up• Train physicians to use the Gram stain• Future?

– Provide images of diagnostic Gram stains (high resolution monitors)

60

11

61