Microbiology Case Study–Upper Thigh Pain

An 85 year old man presented with right medial upper thigh pain and swelling.  Imaging revealed a large pseudoaneurysm in the right superficial femoral artery with evidence of rupture. The patient was taken to the operating room for placement of a gortex stent graft. His postoperative course was complicated by development of a large hematoma at the surgical site. Incision and drainage of the hematoma was surgically performed and fluid from the hematoma was sent to the microbiology laboratory.

Gram stain with multiple gram negative bacilli.
Gram stain with multiple gram negative bacilli.
White-grey bacterial colonies growing on blood agar plate.
White-grey bacterial colonies growing on blood agar plate.
Grey semi-translucent non-lactose fermenting colonies growing on MacConkey agar.
Grey semi-translucent non-lactose fermenting colonies growing on MacConkey agar.

 

Laboratory Identification:

The gram stain and plates confirmed the bacteria were non-lactose fermenting, non-hemolytic gram negative bacilli which is consistent Salmonella. Salmonella species was confirmed by mass spectrometry. Another feature helpful in the identification of Salmonella is its ability to produce hydrogen sulfide. Although not performed in this case, Salmonella will produce colonies with black centers when grown on Xylose lysine deoxycholate agar (selective agar that has thiosulfate which Salmonella metabolize to hydrogen sulfide).

The bacterial isolates of Salmonella were forwarded to the public health laboratories where serotype is determined based on serologic reactions to O and H antigens. The O antigen is the most external component of the lipopolysacccharide of gram negative bacteria and the H antigen is the antigenic determinant that makes up the flagellar subunits . This Salmonella species was identified to be S. enteritidis. Two sets of the patient’s blood cultures also grew S. enteritidis.

Discussion:

Salmonella are motile, gram negative bacilli that are widely disseminated in nature. Various animals such as turtles, lizards, snakes and birds are associated with Salmonella. Salmonella may infect humans via ingestion of contaminated food products that are typically of poultry or dairy origin. Person to person transmission may also occur by fecal-oral route. Salmonella has multiple virulence factors that allow it to evade the immune system. One of its virulence factors is the polysaccharide capsule that surrounds the O antigen. The O antigen is highly immunogenic and shielding the O antigen prevents its recognition by antibodies. Additionally, Salmonella can periodically change its H antigen as another protective mechanism against antibodies.

 

Jill Miller, MD is a 2nd year anatomic and clinical pathology resident at the University of Vermont Medical Center.

Wojewoda-small

Christi Wojewoda, MD, is certified by the American Board of Pathology in AP/CP and Medical Microbiology. She is currently the Director of Clinical Microbiology at the University of Vermont Medical Center and an Assistant Professor at the University of Vermont.

 

The Importance of Truly Internalizing Feedback and Learning From It

Recently, I’ve felt a shift in the timeline. Part of this I can attribute to having less time to myself as I ease into chief resident duties. Time I would’ve spent doing (or postponing) other activities is now relegated to this new role. But this increased demand on my time is not the only factor. Time feels like it is more rapidly passing with each year of residency, and more accelerated as of late.

Taking the annual RISE this time of year also contributes to this. I’m reminded that I should have reached some invisible bar on the meter stick in terms of my knowledge base and hope that I am commensurate with where I should be at this point in my residency. Because sooner than I may feel comfortable with, I will be expected to be “competent” enough to serve as a junior attending during my fellowships. And even though I’ve put it off until a later date, I know that I should also start composing a study plan soon for my boards because time is short between now and graduation.

Lately, probably because it was my most recent rotation, I’m reminded of my surgpath fellows during my PGY-1 telling me that I would learn the most from my cases, both AP and CP. Even though I was listening, I don’t think that I quite understood the depth of those words until my third year. During residency, we often don’t have much time to think because our service duties occupy much of that time. And the desire and need for sleep occupies much of the remainder of the time. But the light bulb moment has gone off so to speak in terms of what they meant by “learning from my cases” – be deliberate and start early.

For much of my first two years, as I’ve previously written, I’ve had a love/hate relationship with surgpath. Maybe those words are too strong, because I neither loved nor hated it, more like was ambivalent toward it. I naturally gravitated toward those subspecialties (obviously not surgpath) that I felt more comfortable with because of my previous training and interests – we all do.

But now I find that grossing is more meaningful and less of a chore to get through for me because I truly understand now how important it is that I do it well – be able to identify the important lesions and sections (90-95% of the diagnosis is off the gross, after all), cut thin and deliberate sections that look like “sushi” as one resident described my grossing, and understand how the sections I provide contribute to staging in the case of cancers. I understand these aspects better now because my grossing skill was called into question during my 2nd year. Since then, I’ve put a good amount of effort into correcting any deficiencies. Even the rotation director who originally brought up this issue, joked about the disasters of my first day on surgpath at his hospital at every end-of-the-rotation evaluation I had since then. His method of feedback may have been dramatic at the time but he really did provide me with a defining moment that changed my outlook and approach and for that I am grateful.

But it’s necessary to be deliberate and start early whatever rotation you’re on. Even though I read about the diagnoses for most of my big resection cases or at least did a quick pathology outlines search each time, I really wish that I would’ve spent even more time really reading up on those cases besides the cursory skim to come up with a diagnosis earlier in my residency. These days, I try to read a little every day, whether it be from a textbook or a journal article. And I’ve found that my knowledge, understanding, and skills improve at a faster rate. But I do wish that I had started this process from my PGY-1 so that I wouldn’t feel like I’m behind where I should be in terms of being ready for boards…so that I didn’t feel like I’m going to have to cram like I used to during college and med school for boards or wonder how to retain info that I learned two years ago on a rotation I haven’t had since PGY-1.

So really listen to the feedback from those more experienced then you. It probably took them longer than they would’ve liked to get to that light bulb moment. That is probably why they are making it a point to bring up that pearl of wisdom to you that they should’ve and wished they could’ve known then.

 

Chung

-Betty Chung, DO, MPH, MA is a third year resident physician at Rutgers – Robert Wood Johnson University Hospital in New Brunswick, NJ.

Microbiology Case Study–Abdominal Pain

A 60 year old man presented with abdominal pain and bloody diarrhea. He denied fever, chills, nausea, vomiting or recent travel. A stool culture was sent to the microbiology laboratory.

Colony Gram stain showing Gram-negative bacilli
Colony Gram stain showing Gram-negative bacilli
Grey-white bacterial colonies growing on a blood agar plate.
Grey-white bacterial colonies growing on a blood agar plate.
Fuschia colonies growing on CHROMagar O157.
Fuschia colonies growing on CHROMagar O157.

 

Laboratory Identification:

E. coli O157:H7 is most likely to be detected in the acute phase of illness and may be missed after 5-7 days from onset of symptoms. In general, laboratory identification is based on the detection of Shiga toxin-producing strains or detection of the O157:H7 serotype through various methodologies. In our laboratory, we identified E. coli O157 based on the above gram stain and colony morphology in combination with growth with the appropriate color on a selective plate for E. coli O157, CHROMagar O157. We used our automated microbial identification system, Vitek 2, which performs multiple biochemical reactions to confirm the bacteria as E. coli O157:H7. Additionally, we identified the presence of Shiga toxin through an immunochromatographic lateral flow rapid test using monoclonal antibodies specific to Shiga toxins.

 

Discussion:

E. coli are gram negative rods that are beta hemolytic, indole positive and lactose fermenters. E. coli is part of the normal colon flora but certain types of E. coli can cause disease depending on their virulence factors. Enterohemorrhagic E. coli (EHEC), also known as Shiga toxin producing E.coli (STEC), is one of six major groups of E. coli that causes diarrhea. EHEC produce a Shiga toxin that inhibits protein synthesis of intestinal epithelial cells via inhibition of the 60S ribosome. The most common serotype is E. coli O157:H7. Transmission occurs through ingestion of raw milk or uncooked ground beef. Hamburgers have been the cause of many outbreaks of infection in the United States although majority of E. coli O157:H7 infections are not associated with outbreaks.

Clinical manifestations from E. coli O157:H7 infection usually occurs at three days from time of exposure but may vary from one to eight days. Clinical symptoms typically begin with abdominal cramps, vomiting, and bloody diarrhea without fever. However, patients may experience a spectrum of disease ranging from asymptomatic infection (less common) to hemorrhagic colitis with progression hemolytic-uremic syndrome (HUS). HUS is the most common cause of acute renal failure in children and results from toxin-mediated damage of endothelial cells in the kidney. HUS is characterized by the triad of acute renal failure, microangiopathic hemolytic anemia, and thrombocytopenia. Supportive therapy is recommended for treatment of E. coli O157:H7 infections. Antibiotics are not recommended because of the potential to increase Shiga toxin production. For this reason, we do not report antibiotic sensitivities for E. coli O157:H7.

 

Jill Miller, MD is a 2nd year anatomic and clinical pathology resident at the University of Vermont Medical Center.

Wojewoda-small

Christi Wojewoda, MD, is certified by the American Board of Pathology in AP/CP and Medical Microbiology. She is currently the Director of Clinical Microbiology at the University of Vermont Medical Center and an Assistant Professor at the University of Vermont.

Hematology Case Study: 60-Year-Old Male with Hives

A 60-year-old male presents with hives, skin flushing, and headaches. After an appropriate preliminary work-up, a bone marrow biopsy is performed. A representative section from the bone marrow biopsy is shown here. What are the granulated cells at the center of this image?

mast

A. Megakaryocytes
B. Promyelocytes
C. Mast cells
D.Myeloma cells
E. Adenocarcinoma cells

The granulated cells in this image are mast cells, which are identified by their abundant, metachromatic granules. This patient was diagnosed with systemic mastocytosis, a clonal disorder of mast cells and their precursors.

Mastocytosis is actually a spectrum of rare disorders, all of which are characterized by an increase in mast cells. Most patients have disease that is localized to the skin, but about 10% of patients have systemic involvement, like the patient in this case. There is a localized, cutaneous form of mastocytosis called urticaria pigmentosum that happens mostly in children and accounts for over half of all cases of mastocytosis.

Clinically, the skin lesions of mastocytosis vary in appearance. In urticaria pigmentosum, the lesions are small, round, red-brown plaques and papules. Other cases of mastocytosis show solitary pink-tan nodules that may be itchy or show blister formation. The itchiness is due to the release of mast cell granules (which contain histamine and other vasoactive substances).

In systemic mastocytosis, patients have skin lesions similar to those of urticaria pigmentosum – but there is also mast cell infiltration of the bone marrow, lymph nodes, spleen and liver. Patients often suffer itchiness and flushing triggered by certain foods, temperature changes, alcohol and certain drugs (like aspirin).

Krafts

-Kristine Krafts, MD, is an Assistant Professor of Pathology at the University of Minnesota School of Medicine and School of Dentistry and the founder of the educational website Pathology Student.

Tumor Boards and Multidisciplinary Conferences (MDC)

Even if we are not as visible to the patients that we care for as other physicians, pathologists are amazing! Of course, I admit that I’m biased since I am a pathology resident but, this does not make this fact any less true. Others may not always realize that pathologists often have to make life altering diagnoses on the most miniscule of tissue samples. Or that we need to incorporate clinical histories, imaging, and previous clinical test and pathology results just as much as the primary clinician, I’ll dare say, sometimes, even more so, since we often do not have the opportunity to talk with the patient face-to-face. And that in the future, especially as precision medicine develops an increasing foothold in the treatment decision making process, we should, and will be, taking more active leadership roles within multidisciplinary teams.

One of the places where I feel that pathologists can show their value to the patient care team is in the multidisciplinary conference (MDC) setting. These can include tumor boards where we discuss specific patient cancer cases or other interdepartmental conferences where we explore an area of common interest that doesn’t necessarily have to be neoplastic. “Doctor” is derived from the Latin word, docere, which means “to teach” and it is within MDC’s that we can shine as teachers. It is impossible to learn about you need to know in medical school in terms of patient care. Not only is the fount of knowledge ever increasing but also our training directs us toward subspecialization since the volume knowledge is so vast, we have to choose which areas we will spend more time mastering.

Way back in the day, surgery residents had to spend significant time (often at least six months) rotating on the surgical pathology service. I find that these more experienced attendings are often the ones who scrub out and sit with our pathologists at the multi-headed scope during frozen sections. And they are also the ones who can make the surgical pathology diagnosis and know the staging summaries even better than junior, and even some senior, pathology residents. But training requirements change. Most of the other clinical physicians we will interact with as colleagues were not trained in this manner.

One of the reasons I chose hematopathology was because I enjoy the daily increased face-to-face interaction I experienced while on this rotation. At most of the hospital sites I’ve trained (four at my previous program and two at my current program), hem/onc physicians and fellows often make the trek to the pathology department to discuss patient cases with the hematopathologist, especially over the microscope. They had some idea of what they were looking at, too. In fact, at a couple of the programs I interviewed (Hopkins and UW), hem/onc physicians are, or were in past in the case of UW, responsible for reading the liquid specimens (peripheral blood smears and aspirates). They also often had multiple interdisciplinary conferences – leukemia, lymphoma, coagulation/benign heme.

But, since I’m on a surgical pathology rotation right now, I was thinking about when we interact most with our surgeons – and I think that is during tumor board. A few of the “old school” surgeons will scrub out and come to the department to look over a frozen with us but most often than not, this is not the case. But during tumor boards, there is always active discussion which includes the pathology in order to come to a treatment decision on not-so-straightforward cases. And these are opportunities to demonstrate just how important the pathologist is to the process. At least in the difficult cases, we do not merely write out diagnoses for other doctors to read and move on without us to treat the patient. It is in these moments when we not only educate but can also actively participate in helping to direct care. But in order to do so, we need to be able to integrate the clinical, epidemiologic, morphologic, radiologic, ancillary diagnostic, and prognostic (lots of “-ogics” there) factors along with know the potential treatment alternatives. We don’t just deal with the morphologic and leave everything else to the referring physicians…at least, if you want to be the best pathologist that you can be. This is also the time when we can leave a lasting impression on other trainees (medical students, residents, and fellows) about how a pathologist can contribute when added to the team mix so that they will be more apt to seek out and work together with pathologists when they become attending physicians.

We are the physicians who understand the intricacies and implications of many of the ancillary tests if we understand well how they are performed and why and also what can cause erroneous or false positive/negative results. I think that I learned a lot of those types of things through serving as an accredited lab inspector (or you can help with your department’s lab self-inspections) and also by being more pro-active during my CP rotations to work with the lab staff and not just sit at my desk and read a book (or study for boards). And we can help guide other physicians regarding which tests are useful for specific situations and which tests really won’t impact prognosis or treatment management. So, be deliberate during your rotations! Try to understand the “big picture” and how important we can be (and really are) in the patient safety and care process! I think that tumor boards and interdepartment MDC’s are a great venue for us to showcase the “true” contributory potential of what pathologists to the patient care team.

Chung

-Betty Chung, DO, MPH, MA is a third year resident physician at Rutgers – Robert Wood Johnson University Hospital in New Brunswick, NJ.

Can You Identify This Structure?

What is this dark structure in the center of this biopsy of a thyroid nodule?

thyroid

A. Foreign body
B. Artifact
C. Psammoma body
D. Area of necrosis
E. Collection of fungal organisms

The structure at the center of this image is a psammoma body. Psammoma bodies are lamellated, calcific structures commonly seen in papillary carcinomas, such as this papillary carcinoma of the thyroid. The exact underlying cause or mechanism of psammoma bodies is not well understood. However, some studies have shown that in papillary thyroid carcinoma, psammoma bodies are associated with a lower disease-free survival and an overall worse prognosis.

Krafts

-Kristine Krafts, MD, is an Assistant Professor of Pathology at the University of Minnesota School of Medicine and School of Dentistry and the founder of the educational website Pathology Student.

Next Steps in Cytotechnology

ASCP and ASC have put together a program to enable cytotechnologists to grow their skills and advance their careers. During this workshop, attendees will learn how to engage as a part of the clinical team and broaden their skill set to include fluorescent in-situ hybridization and interpretation of applied molecular tests.

AJCP_ACE

If you’d like to attend this program, you can register before April 30 to get a discount.