Question

Microbiology Case #1 (M-6) A homeless, alcoholic, 59-year-old man, Hugh Grant (just for the purposes of the case study), presented to the emergency room complaining of fever and chills of 4 days’ duration, with dizziness over the last 24 hours. He also complained of intermittent diarrhea and constipation over the past 6 months with occasional bloody stool. He told the physician that he ate what he could due to his circumstances. The patient’s breathing was rapid, but his lung sounds were clear. His temperature was 103°F. Hugh was hypotensive, tachycardic, and had an appreciable heart murmur. Blood was drawn for a complete blood count (CBC) and culture. A stool specimen was collected to test for occult blood, and a chest x-ray was performed. Results of the laboratory tests are shown in Table 1A and in the list following the chart. Table 1A: Hematology Results Complete Blood Count Hugh G. Reference Range WBC 9.1 5-10 x 10^9/L RBC 4 5-6 x 10^12/L Hb 122 135-175 g/L Hct 0.4 0.41-0.53 L/L MCV 100 80-100 fL MCH 32 26-34 pg MCHC 30 31-37 g/dL RDW 15.6 11.0-14.5 Platelets 458 150-400 x 10^9/L MPV 7.2 fL 6.5-12.0 fL RBC morphology 2+ microcytosis 1+ macrocytosis 1+ ovalocytosis 1+ basophilic stippling 2+ hypochromia 1+ polychromatophilia 2+ toxic granulation Rare Döhle bodies Rare hypersegmentation 2 nucleated RBCs Differential Polymorphonuclear neutrophils 52 25-60% Bands 10 0-10% Lymphocytes 35 20-50% Monocytes 1 2-11% Metamyelocytes 2 0% The stool was positive for occult blood. All blood cultures were positive within 24 hours. Gram’s stains from the bottles revealed gram-positive cocci in chains. Subcultures grew readily on BAP and produced small gray gamma-hemolytic colonies. Additional biochemical testing yielded the following: catalase: negative bile esculine agar: growth with black precipitate growth in 6.5% NaCl: negative L-Pyrrolidonyl ß-naphthylamide PYR test: negative. Questions Does Hugh have bacteremia? Does Hugh have septicemia? What is the difference between bacteremia and septicemia? Given the Gram’s stain reaction and morphology of the bacteria, what might be some possibilities for the identity of the organism? Given Hugh’s history, physical findings, other clinical data, and the further biochemical testing that was performed on this isolate, what is the likely identification of this organism? If latex agglutination testing was performed, to which group would this organism belong? What other testing methods might be employed to get a definitive identification of this organism by genus and species? Hugh has a complex medical history and presentation. Describe his blood picture results in correct hematological terms. Give an explanation for toxic granulation. Give 2 reasons for macrocytes and ovalocytes. Give a reason for microcytes. What other tests might be indicated for his occult blood results?

Microbiology Case #1 (M-6)
A homeless, alcoholic, 59-year-old man, Hugh Grant (just for the purposes of the case study), presented to the emergency room complaining of fever and chills of 4 days’ duration, with dizziness over the last 24 hours. He also complained of intermittent diarrhea and constipation over the past 6 months with occasional bloody stool. He told the physician that he ate what he could due to his circumstances. The patient’s breathing was rapid, but his lung sounds were clear. His temperature was 103°F. Hugh was hypotensive, tachycardic, and had an appreciable heart murmur. Blood was drawn for a complete blood count (CBC) and culture. A stool specimen was collected to test for occult blood, and a chest x-ray was performed. Results of the laboratory tests are shown in Table 1A and in the list following the chart.

Table 1A: Hematology Results
Complete Blood Count
Hugh G.
Reference Range
WBC
9.1
5-10 x 10^9/L
RBC
4
5-6 x 10^12/L
Hb
122
135-175 g/L
Hct
0.4
0.41-0.53 L/L
MCV
100
80-100 fL
MCH
32
26-34 pg
MCHC
30
31-37 g/dL
RDW
15.6
11.0-14.5
Platelets
458
150-400 x 10^9/L
MPV
7.2 fL
6.5-12.0 fL
RBC morphology
2+ microcytosis
1+ macrocytosis
1+ ovalocytosis
1+ basophilic stippling
2+ hypochromia
1+ polychromatophilia
2+ toxic granulation
Rare Döhle bodies
Rare hypersegmentation
2 nucleated RBCs
Differential
Polymorphonuclear neutrophils
52
25-60%
Bands
10
0-10%
Lymphocytes
35
20-50%
Monocytes
1
2-11%
Metamyelocytes
2
0%

The stool was positive for occult blood.
All blood cultures were positive within 24 hours.
Gram’s stains from the bottles revealed gram-positive cocci in chains.
Subcultures grew readily on BAP and produced small gray gamma-hemolytic colonies.
Additional biochemical testing yielded the following:
catalase: negative
bile esculine agar: growth with black precipitate
growth in 6.5% NaCl: negative
L-Pyrrolidonyl ß-naphthylamide PYR test: negative.

Questions
Does Hugh have bacteremia? Does Hugh have septicemia? What is the difference between bacteremia and septicemia?
Given the Gram’s stain reaction and morphology of the bacteria, what might be some possibilities for the identity of the organism?
Given Hugh’s history, physical findings, other clinical data, and the further biochemical testing that was performed on this isolate, what is the likely identification of this organism?
If latex agglutination testing was performed, to which group would this organism belong?
What other testing methods might be employed to get a definitive identification of this organism by genus and species?
Hugh has a complex medical history and presentation. Describe his blood picture results in correct hematological terms.
Give an explanation for toxic granulation.
Give 2 reasons for macrocytes and ovalocytes.
Give a reason for microcytes.
What other tests might be indicated for his occult blood results?

Added by Jennifer G.

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