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Emerging Infections: historical perspectives, precipitating

factors, and pathologic diagnosis

Laura W. Lamps M.D.Godfrey D. Stobbe Professor of Gastrointestinal Pathology

University of Michigan Department of Pathology

Patient Safety Officer, Michigan Medicine

Disclosure

• I have nothing to disclose. Except that my silly dogs will feature prominently in this lecture.

What we are going to do today• Introduction

– What is an emerging infectious disease?– Risk/probability matrix in pathology

• Case examples• Revisit risk/probability in pathology and why

we should study rare things

What is an “emerging” infectious disease?

• (1) A totally new or previously unrecognized organism:– HIV

– Probably crossed species in 1920s– Virus characterized in 1980s

– Hepatitis C (1988)– Hantavirus (1993)– SARS (2003)

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What is an “emerging” infectious disease?

•(2) A previously recognized organism that has been recently identified as a true pathogen:

– H. pylori– Aeromonas spp

What is an “emerging” infectious disease?

• (3) A known pathogen that has undergone changes such that it is increasing in incidence or geographic range:– Basidiobolomycosis (unknown)– Schistosomiasis (dam building)– Lyme disease (reforestation favoring ticks and

deer near homes)– Cryptosporidium (contaminated surface water,

faulty water purification)

Factors that contribute to “emerging” infectious diseases

• Antibiotic resistance• New (permissive) environment

– Transportation, travel, migration– Urbanization with new exposure to pathogens

or vectors– Food/water contamination

• New (vulnerable) host population– Immune deficiency

Vulnerable Host PopulationsWho is immunocompromised?

• AIDS

• Chemotherapy

• Solid organ and bone marrow transplants

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Vulnerable Host PopulationsWho is immunocompromised?

• Elderly patients

• Young children

• Patients with CIIBD, autoimmune

disease on chronic immunomodulator

therapy

• Corticosteroid use

Vulnerable Host PopulationsWho is immunocompromised?

• Diabetics

• Patients without spleens

• Chronic alcoholism

• Malnutrition

• Any chronic debilitating disease

My Favorite Question• Why should I study infectious diseases? We

never see them. – A. So you only study the things you might see

regularly? Like hernia sacs?– B. Either that, or you do see them but you don’t

recognize them.– C. I guess I’ll just go home then.– D. All of the above.

Risk/Probability Matrix• Probabilistic risk assessment (PRA) is a tool

used to define the potential impact of an occurrence, activity or action. Risk is characterized by two things:– Likelihood (probability) each consequence

actually happening– Magnitude (severity) of the possible adverse

consequence(s)

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Risk impact/probability chart Risk impact/probability chart

Heart attackMinor

drug reaction

Viral pandemic

Lung SCC in a smokerH. pylori

infection

Many of the cases for discussion today

Give us the chicken. We’ll check it for Salmonella.

Case Example #1

• A 45 year old migrant worker, currently employed in Arizona, presented with severe abdominal pain. Imaging studies showed a large near-obstructing colonic/pericolonic mass that was suspicious for malignancy. A segmental resection was performed.

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Prominent eosinophils Extensive necrosis

Granulomas

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Organisms are rare, not angioinvasive, and associated with Splendore-Hoeppli material

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Emerging Infection: Basidiobolomycosis

• Basidiobolus ranarum, closely related to Mucormycosis (Entomophthorales)

• Worldwide soil saprophyte– Until recently, primarily considered a

subcutaneous infection (site changing)

– Most cases reported in Saudi Arabia, Africa, South America; current cohort of cases in Arizona (geography changing)

Gastrointestinal Basidiobolomycosis

• GI cases can mimic malignancy, idiopathic inflammatory bowel disease

• Most cases respond to long-term antifungal therapy, but colonic perforation, dissemination, and death are well-documented

Basidiobolomycosis

• Vulnerable populations:– Children– Peptic ulcer disease– Diabetes– Pica– Ranitidine use– Living in an endemic area

Low probability, high impact event• We report here the case of a 55-year-old man from Mali, who

presented with abdominal pain. Radiological exploration revealed an ileo-colonic mass surrounding the appendix. A biopsy was taken and on histology, transmural granulomatous inflammation of numerous eosinophils, lymphocytes, plasmocytes and giant cells was seen. Tuberculosis was suspected clinically and an antibiotic treatment was initiated. Two months later, the patient died of septic complications. Basidiobolus ranarum was identified by PCR. Pathogens were retrospectively highlighted on biopsies. Gastro-intestinal basidiobolomycosis is rare and presents considerable diagnostic difficulty. This infection needs to be diagnosed because surgical resection and prolonged antifungal treatment are curable in most cases.

Cazorla et al. Ann Pathol 2014;34:228-32

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Mucor vs. Basidiobolomycosis

Mucor

• Angioinvasive• Abundant organisms• No Splendore-Hoeppli

• Necrosis • Not eosinophilic• Diabetics, ketoacidosis

Basidiobolomycosis

• Not angioinvasive• Fewer organisms• Splendore-Hoeppli

• Necrosis and granulomas• Markedly eosinophilic• Farm workers, desert

dwellers

GI Mucormycosis

• Often caused by colonization of ulcers

• Stomach and colon are most frequently involved sites

• Ulcers often have heaped-up, rolled edges that mimic malignancy grossly

• Pathologic features very similar to aspergillosis

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Summary

• Basidiobolomycosis resembles mucormycosis, but is not angioinvasive and has a different tissue reaction

• Suspect in patients from endemic areas with paracolonic masses

• Patients often not immunocompromised

• Mucor in the sinonasal tract is a medical emergency

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Alys searches for soil saprophytes.

Case Example #2

• A 25 year old Chinese exchange student presented with diarrhea and lower GI bleeding. CT scan showed a thickened colon and liver lesions. Colonoscopy showed areas of friable mucosa. Biopsies were obtained.

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Emerging Infection: Penicillium marneffei

• Dimorphic fungus

• Endemic in Southeast Asia and Far Eastern Asia

• Most commonly involves lungs and liver, followed by GI tract

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Emerging Infection: Penicillium marneffei

• Now one of the most common opportunistic infections in Asian patients with AIDS– Travel/immigration– Immunocompromise

P. marneffei

• Inflammatory response is granulomatous, suppurative, or mixed

• Yeast forms are septate (“pill capsule”) and similar to histoplasmosis, but they do not bud– Occasional elongated “sausage” forms

with prominent septum

• Require months of antifungal therapy, and dissemination can be rapidly fatal

Low probability, high impact event• Results: A total of 47 AIDS-associated

penicilliosis were confirmed by fungal culture, which accounted for 4.8% of 981 AIDS-related admissions. Two independent predictors for early mortality (death within 12 weeks) of the patients (21.3%, 10/47) were a delayed diagnosis and no treatment with antifungal therapy.

Zheng et al. A clinical study of AIDS-associated Penicillium marneffei infection from a non-endemic area in China. PLoS One June 17 2015

Courtesy Dr. David Walker

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Fungus Exposure Histology Stains

Histoplasma capsulatum

Ohio/MS river valleys

Uniformly small oval yeast with buds at pointed pole; “Halo” in tissueUsually in macrophages

GMSPAS

P. marnefeii Asia Small nonbudding septated yeast

GMSPAS

Cryptococcus neoformans

Worldwide Variably sized yeast with narrow based buds

GMS, PASMelaninMucicarmine

Blastomyces dermatitidis

Ohio and MS river valleysGreat LakesNW Ontario

Large yeast with broad based buds

GMSPASGram negative

Candida torulopsis Worldwide Small budding yeastOften extracellularNo hyphae

GMS, PAS

Characteristics of Yeast in Tissue Sections

Courtesy Dr. Rodger Haggitt

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Courtesy Dr. Brian West

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Summary

• P. marneffei is now one of the most common infectious diseases among Asian AIDS patients

• Given travel and immigration, seen more and more in the USA

• Must be distinguished from other small intracellular fungi

We see you have bacon. We also enjoy bacon.

Case Example #3

• A 46 year old HIV-positive man presented with fever and weight loss.

• CT scan showed mesenteric lymphadenopathy. A mesenteric lymph node biopsy was performed.

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Mycobacteria-associated (MAI) spindle cell nodule

Emerging Infection: Atypical (non-Tubercular) Mycobacteria

• Tremendous geographic variability• Increasing in patients without AIDS• Increasing in patient populations with

chronic pulmonary disease, immunosuppressive medications and comorbid diseases– 25% of patients in one large study had no

known risk factors

Atypical (non-Tubercular) Mycobacteria

• Ubiquitous soil, milk, food, and water inhabitants

• Four major groups that cause infections all over the body

• MAI is most commonly encountered

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Selected sites of atypical mycobacterial infection

MAI M. kansasii

M. absces-sus

M. for-tuitum

M. smeg-matis

M. che-lonae

M. marinum

M. ulcer-ans-

M. szul-gai

Lung x x x x x

GI xSpindle cell nodule

x x

Bone/soft tissue

x x x x x x x

Liver x x

MAI

• Inflammatory reaction very variable:– Site of infection– Immune status of host– Patterns:

• Foamy histiocyte infiltrate• Epithelioid granulomas• Spindle cell nodule• Fibrin ring granuloma

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Low probability, high impact event• The FNA revealed cohesive, dense cellular fragments consisting of

spindle cells with elongated nuclei and ill-defined, pale cytoplasm….scattered spindle cells showed cytologic atypia, including enlarged, rounded nuclei with prominent nucleoli. Poorly formed granulomas comprised of epithelioid histiocytes and lymphocytes were also present….Aspirated material was sent for mycobacterial culture due to the presence of granulomatous inflammation. The diagnosis was rendered descriptively….a neoplasm was favored due to the presence of atypical spindle cells. Due to the presence of cellular atypia possibly representing a neoplasm, the patient underwent surgical resection. The histologic material revealed extensive subcutaneous necrotizing granulomatous inflammation consistent with an infectious process. Cultures collected at the time of the FNA subsequently grew Mycobacterium chelonae.

Holmes et al, Diagnostic Cytopathology 2014;42:772-4.

MAI-Differential Diagnosis

• M. tuberculosis– Culture, PCR– Different inflammatory reaction (usually)

• Other atypical mycobacteria• Other neoplasms (spindle cell nodule)

– AFB stain– CD68– Mycobacteria will stain with desmin, actin,

keratin

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SummarySpecies Matters

• Diagnosis not final just because it’s not MTb

• All atypicals are not MAI

• Therapy varies by species

• If you see organisms but PCR is negative, doesn’t mean you hallucinated, just that block is exhausted

Where are the snacks? Case Example #4

• A 30 year old woman presented with severe abdominal pain and diarrhea. Upon endoscopy, she had a right-sided colitis; the clinical differential diagnosis included ischemia and Crohn’s disease. Biopsies were obtained.

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Emerging Infectious Disease: Shiga toxin producing (enterohemorrhagic) E. coli

• Most common Gram-negative human pathogen

• Major diarrheagenic E. coli– Enterotoxigenic– Enteropathogenic– Enteroinvasive– Shiga toxin-producing (EHEC or STEC)

• O157:H7 most common, but many others

– Enteroadherent

EHEC

• Bloody diarrhea after 1-5 days of nonbloody diarrhea

• Mild or no fever• No fecal leukocytes• Looks like right colon ischemia• Up to 40% develop HUS

– Age (children more susceptible)– Serotype

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Low? frequency, high impact event• HUS [of childhood] typically follows an enteric infection with a Shiga

toxin-producing Escherichia coli, usually belonging to serotype O157:H7. The antecedent infection is almost always manifested as non-bloody diarrhea. In about 80% of cases, the diarrhea becomes bloody between one and five days after the onset of diarrhea. Best clinical practices involve rapid and accurate clinical and microbiological identification of infected patients, volume expansion, and support of the intestinal and extraintestinal complications that can ensue during acute enteric infection and associated HUS. Clinical clues include a sequence of events where the stool becomes bloody after a several-day interval of nonbloody diarrhea, considerable abdominal pain, five or more stools in the 24 h before presentation, pain on defection, and absence of fever at the time of presentation. Diagnosis should rely primarily on sorbitol MacConkey agar culture. Shiga toxin testing should not be used as the only screen to identify infected patients.

Yahata et al. Epidemiol Infect 2015;143:2721-32

Recent EHEC Outbreaks

• 2014– Raw clover sprouts, beef

• 2013– Ready to eat salads and Farm Rich Brand frozen

foods

• 2012– Organic spinach and spring mix, clover sprouts

• 2011– Lettuce, bologna, hazelnuts– Raw beef in Japan (6% death rate)

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Infections that Mimic Ischemia

STEC

Right colon

Food associated

Cultures +

CMV

Inclusions in endothelial cells with associated

thrombosis

Immunocom-promised patients

Angioinvasive fungi

Invasive fungi within and

occluding vessels, with necrosis

GMS positive

Immunocom-promised patients

C. difficile

Pseudo-membranes,

exploding crypts

Abx-associated

C. diff testing

Summary

• History– Food– Antibiotics– Inappropriate setting for ischemia

• Stool culture– Tell clinical lab you are worried so they use

the right agar– Cultures must be taken early

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Summary

• Most STEC outbreaks are underreported and under-diagnosed

• Suspect anytime you see ischemic appearing changes in the right colon

• Let the micro lab know so they can culture appropriately

Watching for emerging infectious diseases. They can come from anywhere.

Case Example #5

• 40 year old man with chronic watery diarrhea. Patient had unintentional 25 pound weight loss in previous month.

• Colonoscopy and EGD essentially normal, but biopsies taken.

Villous blunting and crypt elongationPicture courtesy of Dr. Joel Greenson

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Coccidians in the News

• 2014: Cryptosporidiosis outbreak in public water supply in Sweden

• 2011: Firefighting episode in Indiana leads to cryptosporidiosis

• Summer, 2015: Texas Cyclospora outbreak

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Coccidians

• Parasites that cause diarrhea in both immunocompromised and immunocompetent patients– More serious diarrhea, malabsorption in

immunocompromised– Often asymptomatic in immunocompetent

• Transmitted through food, water, person-to-person

Coccidians

• Endoscopic exam usually normal

• Useful stool studies require special stains

• Mucosal biopsies very effective for dx• ELISA, IHC, PCR available but not widely

used

Implications of easily overlooked pathogens (most of which can be seen on routine H&E)

• Thirty three consecutive patients infected by human immunodeficiency virus type 1 (HIV1) with persistent diarrhoea which remained undiagnosed after microbiological examination of six stool samples and rectal histology were investigated for malabsorption. All had xylose and Schilling tests, distal duodenal biopsy, comprehensive barium studies, microbiological examination of six further stool samples, and repeat rectal histology. A microbiological or histological diagnosis of infection was made in 12 patients (multiple organisms in three). Cryptosporidia were identified on five occasions, cytomegalovirus on four, Giardia lamblia on two, and herpes simplex, Campylobacter jejuni, Salmonella enteritidis, and Entamoeba histolytica once each. Pathogens were identified in nine of 13 patients (69%) with weight loss greater than 10 kg and stool volume more than 800 ml/day.

Connolly et al. Gut 1990;31:886-9

Comparison of Enteric “Coccidians*”Feature Microsporidia Cryptosporidia Cyclospora Cystosospora

Size 2-3µ (smallest) 2-5 µ 2-3µ schizonts5-6µ merozoites

15-20µ (largest)

Location Epithelial cells Apical surface Upper epithelium

EpitheliumMacrophages

Staining Mod trichromeGiemsaGramGMSPAS

GiemsaGram

Acid fastAuramine

GiemsaGramPASGMS

Other Birefringent under polarized light

Bulges out of luminal apex of enterocyte

Parasitophor-ous vacuole

Parasitophor-ous vacuoleEosinophils

*Microsporidia are now classified as fungiCryptosporidia are still parasites, but gregorines, not coccidia

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Microsporidia: Surface epithelial cell disarray and vacuolization

Either spores or plasmodia may be presentPicture courtesy of Dr. Joel Greenson

Gram stain highlights sporesPicture courtesy of Dr. Joel Greenson

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Modified trichrome stain highlights organismsCyclopora: surface epithelial cell disarray

Case and pictures courtesy of Dr. Rhonda Yantiss

Round schizonts and banana shaped merozoites in parasitophorous vacuoles

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Isospora: Schizonts and merozoites with parasitophorous vacuoles and epitheial cell disarray

Picture courtesy of Dr. Joel Greenson Courtesy Dr. Keith Lai

Enteric “Coccidians”Clinical

Infect biliary tree

Capable of dissemination

Infects immunocompetent people

Susceptible to antimicrobials

Cryptosporidia x x x +/-

Microsporidia x x Rare +/-

Cyclospora x Not well documented

x x

Cystoisospora x Rare x x

Enteric “Coccidians”Differential Diagnosis

• Almost all other intracellular organisms will be within macrophages, and not at the luminal surface– Leishmania– Toxoplasmosis– Fungi (Histoplasmosis, P. marneffei)

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LeishmaniasisCourtesy Dr. Rhonda Yantiss

Summary

• Infection by coccidians not limited to immunocompromised

• Mucosal biopsy +/- special stains is best for diagnosis

• Stool studies can be helpful but only with special stains

• May have minimal associated tissue reaction, so remember to look for them

Shouldn’t have had that last beer…

Case Example #6

• 50 year old woman with reported history of Crohn’s disease was taken to emergency surgery for disease flare

• Patient had been on several weeks of steroids with no improvement

• Following right colectomy, patient clinically decompensated, developed pneumonia, and was intubated

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Chronic, active colitis with architectural distortion and basal plasmacytosis

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Deep areas of ulceration with inflammatory exudate

Neural hyperplasia

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Mesenteric lymph node

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Emerging Infection: Strongyloidiasis

• Soil nematode with worldwide distribution, endemic in southeast USA

• Autoinfective capability allows them to live in the small bowel for up to 30 years or more

• Steroids cause the conversion of chronic, low grade disease into fulminant infection in many cases

Low probability, high impact event• Strongyloides stercoralis colitis is a severe, but easily curable, form of

strongyloidiasis that carries a high mortality rate if untreated. ..Our experience with 4 cases of Strongyloides colitis prompted us to assess the clinical outcome of the disease by literature review. In this case series, the misdiagnosis and resultant mortality rates of Strongyloides colitis are 52% and 39.1%, respectively. A low index of suspicion and morphologic resemblance to ulcerative colitis were the main sources of diagnostic error. Ulcerative colitis alone accounted for 38.5% of the erroneous diagnoses. Features of Strongyloides colitis that contrast with those of ulcerative colitis include (1) skip pattern of the inflammation, (2) distal attenuation of the disease, (3) eosinophil-rich infiltrates, (4) relative intact crypt architecture, and (5) frequent involvement of submucosa. We also found that history of steroid therapy, chronic colitis refractory to conventional immune-modifying management, and endoscopic finding of distal attenuation of the colitis are helpful clues. It is also our experience that if Strongyloides colitis is included in the differential diagnosis, the correct diagnosis can usually be made. Current therapy with ivermectin or albendazole is very effective at a cure rate greater than 98%. We believe that the misdiagnosis and mortality rates of this curable, but often, unnecessarily deadly, infectious disease are alarming and warrant efforts to increase the awareness of the disease.

Qu Z et al. Hum Pathol 2009;40:572-7

StrongyloidiasisPathology

• Found anywhere in stomach, small bowel, or colon

• May have minimal inflammatory reaction

• Some patients have neutrophilic/eosinophilic infiltrate, granulomas, ulceration, villous blunting

Worms have sharply pointed, often curved tails and are found in crypts

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A neutrophilic or eosinophliic infiltrate can be seen in association with the parasite

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Differential Diagnosis

• Larvae/worms with sharply pointed tails within epithelium is essentially diagnostic– In the proper geographic setting,

capillariasis could mimic strongyloidiasis

• Schistosomiasis: eggs, not worms

• Enterobius: too big, in lumen• Anisakiasis: huge, in stomach, sushi

Summary

• Almost always a history of steroid use• Fulminant infection can mimic chronic

idiopathic inflammatory bowel disease• If you see pockets of eosinophils on

biopsy, consider recuts to look for strongyloides

• Stool exam for O&P, serologies can be helpful

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So why should I study infectious disease pathology?

• Pathogens (particularly emerging ones, as their characteristics are changing) are important and often under-recognized• History, food intake, risk factors, environmental

exposure often critical

• In the GI tract, emerging infections are a clinically significant problem– Particularly in immunocompromised patients

• Immunocompromised means lots of things

So why should I study infectious disease pathology?

•Lots of pathogens can’t be cultured, everything is in formalin, or cultures/molecular take a long time•Although cultures/molecular are gold standard, morphology can be extremely helpful in directing therapy, especially early on

Low probability, high impact events and pathology

• Low probability, high impact events are areas of vulnerability in diagnostic anatomic pathology.

• We can learn from those who have studied the risk/probability matrix in other sectors of science and technology.

Lee, Preston, and Green: Preparing for high-impact, low probability events: Lessons from Eyjafjallajokull (2012)

Lessons from the ash cloud

– Rare things by definition are rare, but neither nonexistent or impossible• This requires preparation for things that it’s hard to

even conceive of

– Local things rarely remain local anymore• Infections that spread through food, travel• Weird patterns of metastasis• Weird distribution of vasculitis

– The “grass roots” response is as critical, if not more so, than the government’s response• Residents, this is you. -

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Lessons from the ash cloud

– Collect all the information you can about events (cases), and communicate with others who have information.

– Private citizens (us) must be as invested in the outcome (correct case management and diagnosis) as the government (administration and government).

– Establish and be aware of best practices.– Know the literature (“build up a library of

observations that can be drawn on when preparing for similar shocks in the future.”)

Zoe is exhausted from this discussion.