1. Cases for Labs
Med Labs

2. Sir William Osler -paraphrase
Take the history to make the diagnosis
Examine the patient to confirm the diagnosis
Order lab tests to prove the diagnosis to those who do not believe you
The agents that cause an infection are those that arose from the site of infection
Pathogenesis is how the infection occurred and how it makes one ill

3. Case 1
60 year old male
Previous history of alcohol abuse, presents with 24 hour history of fever, chills and rigors, associated with progressive cough that is purulent and blood tinged
He has become progressively short of breath prompting him to go to the hospital

4. Case 1
What are the likely diagnoses?

5. Case 1 Acute pneumonia Alcohol withdrawal Chronic pneumonia AspirationTB

6. Physical Acutely ill using accessory muscles with peripheral cyanosis
Unable to provide further history
Temperature 40°C, pulse 120 reg, BP 120/50 & respiratory rate 30/minute
Chest has bronchial breathing throughout the right lung and in the left lower lobe

7. Case 1 What physical findings suggest the presence of
Why is the patient using accessory muscles
Acute infection
Acute pneumonia
What is bronchial breathing & what pathological changes in the lung result in this

8. CXR

9. Case 1
What does the chest x-ray tell you

10. Lab WBC 18,000 with 80% PMN’s and 10% bands, 5% lymphocytes Sputum
> 25 PMN per field and no SEC
Gram positive diplococci are abundant
First question:
What is the Gram stain telling you.

12. Initial therapy
Second question: Considering the patient’s continued deterioration what would you consider giving him as initial therapy and why?
Cefotaxime and Vancomycin

13. Lab Blood cultures Sputum cultures
Gram positive diplococci see on smear
Sputum cultures
Heavy growth of α-hemolytic Streptococci
Light growth of normal respiratory flora

14. Streptococcus pneumoniae

15. Lab Blood Sputum α-hemolytic colonies Direct susceptibilities
Zone present around
optochin disk
Bile soluble
Direct susceptibilities
Sputum
Heavy growth of Strep. pneumoniae
Light growth of normal respiratory flora

16. Susceptibility Testing
Blood
Oxacillin screening test no zone
Penicillin MIC 1 mg/l
Sputa Streptococcus pneumoniae
Oxacillin screen test no zone
Penicillin MIC = 1 mg/l

17. Susceptibility Test

18. Therapy Patient left on cefotaxime to S. pneumoniae
Despite adequate therapy he developed further complications and died after 7 days of treatment
Why does the patient die?

19. Case 2
65 year old male with progressive back problems over the last 2 months
Referred by Family Physician to Neurosugeon who arranges for MRI of the spine

20. MRI
Vertebral osteomyelitis is infection in the vertebral body itself. It may be caused by either a bacteria or a fungus. Bacterial or pyogenic vertebral osteomyelitis is more common. Its presentation is different than a disc space infection. It may represent infection elsewhere in the body that has seeded the spine through the blood stream. These patients are systemically ill, exhibiting increased temperature, white blood cell and erythrocyte sedimentation rate. The average time from onset of symptoms to definitive diagnosis has been reported to range from 8 weeks to 3 months. The onset is usually insidious, with back pain the most common symptom. The pain is localized at first to the level of the involved area, with a gradual increase in intensity. The pain eventually becomes so severe it is not relieved by complete bedrest. (This is nice, but I wouldn’t give them the info at this point and have them come up with the differential. We could ask the question and then show a slide or 2 with this information)

21. Biopsy of vertebral lesion

22. Lab WBC 13,000 HGb 110 Platelets 500,000 Aspirate Gram stain
Moderate PMN’s
No organisms seen
ID consulted

23. Further info
Patient is referred to ID and the following information is obtained
Weight loss of 10 pounds over the last 4 months
Remote history of heart murmur
First question:
What are you suspecting?
What should be done?
Intravascular infection with spread to spine
Need to exclude endocarditis
Complete physical examination, blood cultures, assess for other organ invlovement

24. Physical exam Temperature is 37.7°C
Physical exam reveals pansystolic murmur at the apex of the heart that radiates to the axilla
Subconjunctival hemorrhages
Embolic lesions on his toes
Spleen is enlarged & slightly tender
Need to explain the concept of metastatic infection
Primary infection may well have bee urinary but then spread to heart valve & then involved the spine
The subconjunctival hemorrhahes relate to continuous bacteremia and end arteriole emboli
Spleen enlarges secondary to generalized inflammation

25. Janeway lesions Olser nodes
Janeway lesions are flat, red to bluish, painless spots that appear on the hands or feet of patients with acute bacterial endocarditis. Olser nodes are painful erythematous nodules seen in patients with endocarditis.

26. Action Blood cultures: Positive with Gram positive cocci
Cultures of vertebral biopsy:
Enterococcus fecalis
Penicillin susceptible, no high level aminoglycoside resistance
Echocardiogram
Demonstrates mobile mass on the anterior leaflet of the mitral valve

27. Blood culture result

28. Case 2
TTE PLAXV shows a large vegetation (arrow) measuring 1.6 x 1.4 cm attached to the anterior mitral leaflet and partially occluding the MV orifice in diastole. (Abbreviations: LA = left atrium; LV = left ventricle; PLAXV = parasternal long axis view)

29. Diagnosis Endocarditis Mitral valve (native) Enterococcus fecalis
Therapy
6 weeks of Penicillin & Gentamicin
Cardiac and renal function monitored and was stable

30. During therapy
Develops malodorous diarrhea associated with fever, and cramping abdominal pain
? Secondary to antibiotics
? Clostridium difficile associated diarrhea

31. Flat Plate of Abdomen

32. Action Penicillin & Gentamicin held
Empirically started on metronidazole
Second question:
What is the possible cause of this patient’s diarrhea?
Stool sent for C. difficile toxin assay
Third question:
What are the infection control concerns and how will you handle this patient?
Placed in contact precautions due to risk of spread
Antibiotics can cause a change in the bacterial flora of the GI tract and this can result in diarrhea
Loss of endogenous flora and presence of a toxin producing Clostridium difficile can lead to a unique disease called CDAD
Patient needs to be isolated and diagnosis made
Hold antibiotics
C. Diff toxin sent (stool)
Start metronidazole

33. Follow up
Within 72 hours fever has settled and abdominal findings have normalized
Bowel movements return normal in 5 days and then taken off contact precautions
Remains on Metronidazole
Ampicillin & Gentamicin are restarted

34. Case 3 24 year old male Develops painful and swollen knee
Presents to ER unable to weight bear
Denies history of sexually transmitted risk factors

35. Physical exam Temperature 38.3°C Petechial type rash over extremities
Swollen knee with marked reduction in range of movement
Aspirate of the knee joint revealed purulent fluid

36. Case 3 Question 1 Question 2 What are the likely infectious agents
Are there other possible explanations for the swollen knee joint
1) S.aureus, N. meningitidis are the typical agents
2) Non infectious casuses would include crystals, auto – immune

37. Gram stain

38. Case 3 Question 3 & 4 Question 5 & 6 What does the Gram stain show
What are the possible infectious agents
Question 5 & 6
What other sites would you examine & how
What other infections would you test for & why

39. Follow up
Based on smear results patient is tested for Gonorrhea and Chlamydia from urethra and
Both positive and joint fluid positive for N. gonorrhoeae
Also tested for Hepatitis B and HIV
Not immune for HBV therefore immunized
HIV serology negative

40. Case 4
18 year old male
Complicated neurological history secondary to birth defects, limited ability to communicate, parents note that he has become less responsive and may be having seizures
Required VP (ventriculoperitoneal) shunt at age of 4 years
? Low grade fever
Limited ability to clear his secretions

41. Physical exam
Debilitated young male, ? Response to verbal stimuli, appears to be in pain
Temperature 39, HR 120, respiratory rate 20, BP 120 / 70
Abundant oral secretions – mucoid in character
Scattered crackles throughout all lung fields
Abdomen is firm, but not sure if it reflects patient’s generalized discomfort
Scar in upper right quadrant
Neck is stiff

42. Case 4
What infectious diagnoses are you concerned about?

43. A VP shunt – used to drain CSF from a obstructive hydrocephalus

44. Chest X ray

45. Lab
WBC 16,000
HGB 114
Plts 500,000

46. Case 4 Decision made to sample the CSF via the shunt
What test will you order on the CSF
What result would you expect
If infected what are the typical agents involved in VP shunt infections
Biochem (glucose & protein), also blood glucose and protein
Gram stain & culture
Cell count & differential
Low glucose, high protein & positive Gram stain with Gram positive cocci
Typical agents are coag neg Staph

47. Lab CSF Tube 1 Tube 2 Tube 3 Glucose 0.5 Protein 3.5 Gram stain
Abundant white cells
Moderate Gram negative bacilli
Tube 3
WBC’s 300 with 90% PMN’s
No RBC’s
With the Gram negative bacilli attention is turned to the GI tract as a source of infection for the CSF

48. Gram negative meningitis

49. Case 4 What process might explain the infectious process
What tests might you order to investigate this

50. Abdominal Ultrasound - appendicitis
Appendicitis (distended pus-filled appendix) with calcified, shadowing appendicolith (arrowhead) near the base of the appendix on ultrasound

51. Case 4
Infection secondary to appendicitis with retrograde spread up the shunt