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Monday, April 19, 2010
Case of the Week 114
The following brain touch-preparations were stained with giemsa and viewed with a oil immersion objective. Diagnosis? (CLICK ON IMAGES TO ENLARGE)
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Sunday, April 18, 2010
Answer to Case 114
Answer: As stated by cmassey, "Toxoplasma gondii. Criteria: rupturing cyst with what appear to be escaping tachyzoites. Morphology is crescent shape with a large nucleus and they appear to fit in the 4-8um by 2-3um size given in diagnostic literature."
Great job to everyone who wrote in! This case demonstrates a few nice features of T. gondii. First, there are both cyst and free tachyzoite forms as seen here:
Also, many of the tachyzoites demonstrate the classic 'arc' shape (Toxon is Greek for arc):
Great job to everyone who wrote in! This case demonstrates a few nice features of T. gondii. First, there are both cyst and free tachyzoite forms as seen here:
Also, many of the tachyzoites demonstrate the classic 'arc' shape (Toxon is Greek for arc):
Monday, April 5, 2010
Case of the Week 112
The following were seen macroscopically in a duodenal aspirate. They range in length from 7 to 10 millimeters.
When they were viewed microscopically using a 4x objective, the following smaller microscopic objects were also seen in between the macroscopic objects:
Using a 4x objective, the head and tail of the larger objects looked as follows:
Head:
Tail:
Higher magnification revealed that some of these small objects were moving!
Here's one that measures 60 micrometers in greatest dimension.
After some time, the following was observed:
Here's one of the microscopic objects moving. It measures approximately 300 micrometers in length.
Identification?
What would happen if we plated the duodenal aspirate contents on an agar for Strongyloides stercoralis culture?
When they were viewed microscopically using a 4x objective, the following smaller microscopic objects were also seen in between the macroscopic objects:
Using a 4x objective, the head and tail of the larger objects looked as follows:
Head:
Tail:
Higher magnification revealed that some of these small objects were moving!
Here's one that measures 60 micrometers in greatest dimension.
After some time, the following was observed:
Here's one of the microscopic objects moving. It measures approximately 300 micrometers in length.
Identification?
What would happen if we plated the duodenal aspirate contents on an agar for Strongyloides stercoralis culture?
Sunday, April 4, 2010
Answer to Case 112
Answer: Hookworm; specifically Necator americanus
Cmassey said it very well with the following:
"Oh boy! Lots of cool photos! Looks to be Necator americanus with adults in the first photo, eggs and first-stage larva in the second photo, cutting plates in the third photo, bursa of adult male in the fourth photo, followed by eggs and emerging larvae. I feel like this is a trick question but if we plated the aspirate on agar then they should show furrows after some time. Not as well and as deep as Strongyloides but still detectable and more snake-like than whip-like."
Cmassey is correct on all accounts. This is Necator americanus as evidenced by the cutting plates instead of 'teeth' of Ancylostoma duodenale. Furthermore, hookworm larvae will indeed create furrows in agar culture, very similar to those created by Strongyloides stercoralis. If stool is plated directly after being passed, it will take some time for the eggs to mature and hatch the L1 larvae; therefore, it would take a few extra days for the characteristic tracks to be produced in the agar. Remember that hookworm eggs are immature when passed, and take a few days to mature and release larvae. This usually occurs in the soil, but larvae can also be seen in stool when it has been sitting for a few days prior to examination. In this case, the duodenal aspirate was delayed in transit, allowing time for the eggs to mature and hatch.
In regard to the agar culture method, this method was first presented by Tamiki Arakaki in 1988 as a means of increasing the detection of Strongyloides stercoralis from stool. Since the original description, numerous investigators have shown a significant increase in sensitivity over O&P concentration methods and the Baermann funnel technique. Arakaki also noted that hookworm could be seen by the agar method, but that the furrows were characteristically much thicker than those left by Strongyloides larvae, and thinner than those left by free-living adults of S. stercoralis. I'm not sure I would easily be able to tell hookworm from Strongyloides furrows apart, but we could definitely confirm that the hookworm larvae left macroscopically visible tracks in the agar, by migrating through the agar and dragging bacteria with it.
Here's an image from this case:
Nice tracks!
Finally, Anonymous had a interesting suggestion with "Ostertagia ostertagi". This is a parasite of cattle, that has rarely been reported from humans - typically in cases where humans and livestock live in close proximity. However, the characteristic morphology of the adults and larvae in this case were consistent with N. americanus.
Cmassey said it very well with the following:
"Oh boy! Lots of cool photos! Looks to be Necator americanus with adults in the first photo, eggs and first-stage larva in the second photo, cutting plates in the third photo, bursa of adult male in the fourth photo, followed by eggs and emerging larvae. I feel like this is a trick question but if we plated the aspirate on agar then they should show furrows after some time. Not as well and as deep as Strongyloides but still detectable and more snake-like than whip-like."
Cmassey is correct on all accounts. This is Necator americanus as evidenced by the cutting plates instead of 'teeth' of Ancylostoma duodenale. Furthermore, hookworm larvae will indeed create furrows in agar culture, very similar to those created by Strongyloides stercoralis. If stool is plated directly after being passed, it will take some time for the eggs to mature and hatch the L1 larvae; therefore, it would take a few extra days for the characteristic tracks to be produced in the agar. Remember that hookworm eggs are immature when passed, and take a few days to mature and release larvae. This usually occurs in the soil, but larvae can also be seen in stool when it has been sitting for a few days prior to examination. In this case, the duodenal aspirate was delayed in transit, allowing time for the eggs to mature and hatch.
In regard to the agar culture method, this method was first presented by Tamiki Arakaki in 1988 as a means of increasing the detection of Strongyloides stercoralis from stool. Since the original description, numerous investigators have shown a significant increase in sensitivity over O&P concentration methods and the Baermann funnel technique. Arakaki also noted that hookworm could be seen by the agar method, but that the furrows were characteristically much thicker than those left by Strongyloides larvae, and thinner than those left by free-living adults of S. stercoralis. I'm not sure I would easily be able to tell hookworm from Strongyloides furrows apart, but we could definitely confirm that the hookworm larvae left macroscopically visible tracks in the agar, by migrating through the agar and dragging bacteria with it.
Here's an image from this case:
Nice tracks!
Finally, Anonymous had a interesting suggestion with "Ostertagia ostertagi". This is a parasite of cattle, that has rarely been reported from humans - typically in cases where humans and livestock live in close proximity. However, the characteristic morphology of the adults and larvae in this case were consistent with N. americanus.
Monday, March 29, 2010
Case of the Week 111
Objects such as those shown below were seen in a urine specimen submitted for examination. According to the patient, he had passed several of these objects in his urine. Possible identification?
Sunday, March 28, 2010
Answer to Case 111
Answer: Mosquito larvae
Most of you astutely noted that these are NOT organisms you would expect to find inside the urinary bladder, and most likely result from exogenous environmental contamination after the sample was obtained.
At this magnification, you can appreciate the presence of siphons by which the larvae breath oxygen from the above the surface of the water. That puts them in the Culicine subfamily, which includes the Culex and Aedes genera. Given that these larvae are in urine, they are most likely Culex spp., since this species can tolerate high levels of organic pollution, and may be found in cess pits, open drains, and pit latrines.
Most of you astutely noted that these are NOT organisms you would expect to find inside the urinary bladder, and most likely result from exogenous environmental contamination after the sample was obtained.
At this magnification, you can appreciate the presence of siphons by which the larvae breath oxygen from the above the surface of the water. That puts them in the Culicine subfamily, which includes the Culex and Aedes genera. Given that these larvae are in urine, they are most likely Culex spp., since this species can tolerate high levels of organic pollution, and may be found in cess pits, open drains, and pit latrines.
Monday, March 22, 2010
Case of the Week 110
The following larval tracks were seen on an agar plate that had been inoculated with the sputum of an immunocompromised patient from Kentucky. What parasite should you be concerned about? (Tracks are viewed using 4x objective)
Answer to Case 110
Answer: tracks left by Strongyloides stercoralis larvae. In this "culture" technique, stool is typically placed on a beef extract agar plate and incubated at room temperature. If Strongyloides stercoralis larvae are present, they will move out of the stool specimen, dragging bacteria with them. What we're actually seeing in this case the bacteria growing in the wake of the moving larva. These "tracks" can be seen using a dissecting microscope, and are typically present 24-48 hours after initial plating. Using a 4x objection, it is also possible to see "furrows" left in the agar by migrating larvae (without associated bacterial colonies) and the worms themselves.
Since this was a sputum sample, we were concerned that there was not enough bacteria present to allow the larva to create tracks; therefore, we made a 2:1 concentration of sample to Escherichia coli mixture and plated this on the agar.
A few interesting facts about Strongyloides stercoralis culture:
1. This technique was first described by Arakaki et al (1988).
2. In general, it increases the yield of positive cases by 50% or more compared to the formalin-ether concentration method.
3. Furrows and bacterial tracks are suggestion of a migrating larva, but definitive diagnosis is best accomplished by identification of the worm itself.
3. Other nematode larvae, such as free-living larvae and hookworm larvae, can be seen with this technique, so microscopic examination of the worm is important for differentiation. Of note, you would only expect to find these 2 larvae in stool samples that have sat at room temperature for an extended period (e.g. in hookworm infection, since this allows the eggs to hatch into L1 larvae), or if the sample was contaminated by soil that may contain free living nematodes.
4. Finally, as suggested by cmassey, the tracks resemble an aerial photo of the Amazon river flowing into the ocean!
Thanks to everyone who wrote in with comments.
Since this was a sputum sample, we were concerned that there was not enough bacteria present to allow the larva to create tracks; therefore, we made a 2:1 concentration of sample to Escherichia coli mixture and plated this on the agar.
A few interesting facts about Strongyloides stercoralis culture:
1. This technique was first described by Arakaki et al (1988).
2. In general, it increases the yield of positive cases by 50% or more compared to the formalin-ether concentration method.
3. Furrows and bacterial tracks are suggestion of a migrating larva, but definitive diagnosis is best accomplished by identification of the worm itself.
3. Other nematode larvae, such as free-living larvae and hookworm larvae, can be seen with this technique, so microscopic examination of the worm is important for differentiation. Of note, you would only expect to find these 2 larvae in stool samples that have sat at room temperature for an extended period (e.g. in hookworm infection, since this allows the eggs to hatch into L1 larvae), or if the sample was contaminated by soil that may contain free living nematodes.
4. Finally, as suggested by cmassey, the tracks resemble an aerial photo of the Amazon river flowing into the ocean!
Thanks to everyone who wrote in with comments.
Monday, March 15, 2010
Case of the Week 109
The following were an unexpected finding from a ultrasound guided endoscopy and FNA of a pancreatic cyst. Giemsa stained, 400x and 600x.
Question: What anatomic site did these organisms most likely come from?
Case courtesy of Dr. Abdelmonen Elhosseiny
Question: What anatomic site did these organisms most likely come from?
Case courtesy of Dr. Abdelmonen Elhosseiny
Sunday, March 14, 2010
Answer to Case 109
Answer: Trophozoites of Giardia lamblia(aka. G. intestinalis, G. duodenalis)
As many of you guessed, these organisms were most likely picked up in the duodenum when the endoscope was threaded through the small bowel to get access to the pancreatic cyst. I don't know of any reports where Giardia trophozoites actually inhabited a location other than the intestinal lumen.
This is really a beautiful example of the trophozoite morphology, and again, I'd like to thank Dr. Abdel Elhosseiny for this case. The giemsa stain nicely highlights all of the flagella which are not usually seen so clearly in a routine stool Trichrome stain.
Thanks to all for writing in with your comments!
As many of you guessed, these organisms were most likely picked up in the duodenum when the endoscope was threaded through the small bowel to get access to the pancreatic cyst. I don't know of any reports where Giardia trophozoites actually inhabited a location other than the intestinal lumen.
This is really a beautiful example of the trophozoite morphology, and again, I'd like to thank Dr. Abdel Elhosseiny for this case. The giemsa stain nicely highlights all of the flagella which are not usually seen so clearly in a routine stool Trichrome stain.
Thanks to all for writing in with your comments!
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