Opportunistic Infections (Buxton) Flashcards
What are 3 things that can compromise a host?
Defects/injury to physical barriers
Deficiencies in innate immunity
Deficiencies in adaptive immunity
A 12 year old child is severely burned in a house fire. He was hospitalized for over a month with 3rd degree burns on his leg. About a week after admission, he developed an infection of the burned areas. Blue-green pus was associated with the infection.
What factors increased this child’s risk of infection?
Burn - loss of protective skin barrier; severe burns lead to decrease in neutrophil function
Hospitalization - at risk for nocosomial infections
A 12 year old child is severely burned in a house fire. He was hospitalized for over a month with 3rd degree burns on his leg. About a week after admission, he developed an infection of the burned areas. Blue-green pus was associated with the infection.
Which organisms are the most common causes of burn infections?
Pseudomonas aeruginosa (wet areas)
Staphylococcus aureus (skin)
Staphylococcus epidermidis (skin)
Streptococcus pyogenes (skin, mucous membranes)
Candida (skin, mucous membranes)
Aspergillus (soil, dark & damp areas - spores)
*burn infections often polymicrobial*
Pseudomonas on nutrient agar
Aspergillus
Name the following microbes isolated from the 12 y/o burn patient’s blood and/or exudate.
- Gram (+) cocci, catalase (+), coagulase (-)
- Gram (+) cocci, catalase (+), coagulase (+)
- Gram (-) rod, greenish colored colonies on nutrient agar
- fungus in below image
- Staph epidermidis
- Staph aureus
- Pseudomonas
- Aspergillus
Of the 4 microbes isolated from the 12 y/o burn patient’s wounds, what was isolated from his burn? What was isolated from his blood?
Burn - Pseudomonas, Staph epidermidis
Blood - Pseudomonas, Staph aureus, Aspergillus
How did the 12 y/o burn patient become infected?
Skin colonization - Staph
Hospital environment - Pseudomonas, Aspergillus
Describe the pathogenesis of burn wound infections.
Bacteria that colonize skin are first to invade wound (within days). Pseudomonal & fungal infections occur ~1 week after hospitalization. Important virulence factors include resistance to phagocytosis & enzymes that facilitate invasion.
Describe the epidemiology of Pseudomonas.
Ubiquitous
Resistant to some common disinfectants
Antibiotic resistance is common
Causes infections in CF, catheterized, burn, and intubated patients
What are common locations for Pseudomonas infections?
Skin & musculocutaneous tissues
Respiratory tract
CNS
Localized
Blood (bacteremia)
Heart (endocarditis)
Urinary tract (UTI)
Ecthyma gangrenosum - consequence of Pseudomonas septisemia; hemorrhagic necrosis of the skin
How would you treat your 12 y/o burn patient who is positive for Staph epidermidis, Staph aureus, and Aspergillus?
MRSA - Vancomycin, Linezolid, Streptogramin
MSSA - Vafcillin/Oxacillin/Dicloxacillin, 1st/2nd gen. cephalosporin, Clindamycin
Pseudomonas - Extend spectrum penicillin + beta-lactamase inhibitor, carbapemen, Monobactam, fluoroquinolones, Ceftazidime, Cefepime, aminoglycosides
Aspergillus - Voriconazole, Caspfungin
So…Vancomycin + Amp B until data comes back
A newborn baby had a fever and appeared septic. Blood cultures grew a gram-positive coccobacillus that was weakly beta-hemolytic, was motile and grew at 4C. A diagnosis of Listeria monocytogenes was made, and the infection was transmitted from the mother prior to birth.
Why is an infant considered immune compromised?
Decreased: production of neutrophils, killing by phagocytes, complement levels, NK cell activity, in vitro lymphocyte proliferation, cytokine production by lymphocytes, CTL responses, expression of CD40L, production of Ig (especially IgG & IgA).
A newborn baby had a fever and appeared septic. Blood cultures grew a gram-positive coccobacillus that was weakly beta-hemolytic, was motile and grew at 4C. A diagnosis of Listeria monocytogenes was made, and the infection was transmitted from the mother prior to birth.
How did the infant become infected?
Fetal infection can occur from:
transplacental transmission
ascending infection through ruptured amniotic membranes
during birth through an infected birth canal
A newborn baby had a fever and appeared septic. Blood cultures grew a gram-positive coccobacillus that was weakly beta-hemolytic, was motile and grew at 4C. A diagnosis of Listeria monocytogenes was made, and the infection was transmitted from the mother prior to birth.
What were the symptoms, if any, in the mother?
Nausea, vomiting, diarrhea, fever, malaise, back pain, and headache
Many pregnant women can carry Listeria asymptomatically in their GI tract or vagina
Maternal infection with Listeria can affect pregnancy by causing chorioamnionitis, premature labor, spontaneous abortion, or stillbirth
A newborn baby had a fever and appeared septic. Blood cultures grew a gram-positive coccobacillus that was weakly beta-hemolytic, was motile and grew at 4C. A diagnosis of Listeria monocytogenes was made, and the infection was transmitted from the mother prior to birth.
Where is the organism found in nature - how did the mother become infected?
Widely distributed in nature - intestinal tracts of many mammals; most commonly associated with ingestion of prepared meat, dairy products, unwashed raw vegetables, and seafood. Soft cheeses and unpasteurized milk have bee nthe most frequently incriminated dairy products.
A newborn baby had a fever and appeared septic. Blood cultures grew a gram-positive coccobacillus that was weakly beta-hemolytic, was motile and grew at 4C. A diagnosis of Listeria monocytogenes was made, and the infection was transmitted from the mother prior to birth.
How would you treat the baby?
Ampicillin + Gentamicin
A 42 year old woman is hospitalized with pneumonia. Her history is significant for long term corticosteriod use for severe asthma. A sputum gram stain revealed gram-positive bacilli, coccobacillary cells and branching filaments. A modified acid-fast stain showed the organism to be partially acid-fast. The organism was identified as Nocardia sp.
What made this patient susceptible to this infection?
Corticosteroids - long-term use
A 42 year old woman is hospitalized with pneumonia. Her history is significant for long term corticosteriod use for severe asthma. A sputum gram stain revealed gram-positive bacilli, coccobacillary cells and branching filaments. A modified acid-fast stain showed the organism to be partially acid-fast. The organism was identified as Nocardia sp.
What is the source of the bacteria?
Ubiquitous in soil and water
A 42 year old woman is hospitalized with pneumonia. Her history is significant for long term corticosteriod use for severe asthma. A sputum gram stain revealed gram-positive bacilli, coccobacillary cells and branching filaments. A modified acid-fast stain showed the organism to be partially acid-fast. The organism was identified as Nocardia sp.
What are the unusual features of this bacteria?
Cell walls contain mycolic acid, thus pick up acid fast stain
A 42 year old woman is hospitalized with pneumonia. Her history is significant for long term corticosteriod use for severe asthma. A sputum gram stain revealed gram-positive bacilli, coccobacillary cells and branching filaments. A modified acid-fast stain showed the organism to be partially acid-fast. The organism was identified as Nocardia sp.
How should she be treated?
TMP/SMX is drug of choice; other antibiotic combinations can be used
Nocardia
A 42 year old woman is hospitalized with pneumonia. Her history is significant for long term corticosteriod use for severe asthma. A sputum gram stain revealed gram-positive bacilli, coccobacillary cells and branching filaments. A modified acid-fast stain showed the organism to be partially acid-fast. The organism was identified as Nocardia sp.
If patient has pulmonary nocardosis, what symptoms would you expect to find?
Lobar pneumonia with abscess formation
May mimic TB clinically - fever, weight loss, chest pain
Infection can spread from lung to other sites via blood
A 23 year old AIDS patient had fever, night sweats, fatigue and diarrhea for the past 3 months. Over that time, she has lost 22 pounds and is short of breath. Her CD4 count has been below 50/cmm for the past 6 months and her viral load is 55,000/cmm. Routine blood cultures were negative after 48 hours; however, growth was seen after 10 days. DNA probes identified the organism as belonging to the Mycobacterium avium complex.
What are the diagnostic features of this organism?
Group of related organisms - MAC
Bacilli-weakly gram (+), strongly acid fast
MAC infection in aids patient - disseminated acid fast rods in tissue
A 23 year old AIDS patient had fever, night sweats, fatigue and diarrhea for the past 3 months. Over that time, she has lost 22 pounds and is short of breath. Her CD4 count has been below 50/cmm for the past 6 months and her viral load is 55,000/cmm. Routine blood cultures were negative after 48 hours; however, growth was seen after 10 days. DNA probes identified the organism as belonging to the Mycobacterium avium complex.
What are the sources of this organism?
Infect many bird & mammal species
Ubiquitous - in water & soil
Infection thought to occur by ingestion or inhalation
Describe the pathogenesis of disseminated MAC infection.
Enters immunocompromised person via ingestion/inhalation - infects resting macrophages of mucosal epithelium - carries organism throughout body (lymphatic sites) - replicates to very high numbers within macrophages within various tissues - infected macrophages secrete cytokines - cytokine storm
A 23 year old AIDS patient had fever, night sweats, fatigue and diarrhea for the past 3 months. Over that time, she has lost 22 pounds and is short of breath. Her CD4 count has been below 50/cmm for the past 6 months and her viral load is 55,000/cmm. Routine blood cultures were negative after 48 hours; however, growth was seen after 10 days. DNA probes identified the organism as belonging to the Mycobacterium avium complex.
What diseases does it cause in immune-competent individuals?
Pulmonary disease in persons with underlying lung conditions, smokers
A 23 year old AIDS patient had fever, night sweats, fatigue and diarrhea for the past 3 months. Over that time, she has lost 22 pounds and is short of breath. Her CD4 count has been below 50/cmm for the past 6 months and her viral load is 55,000/cmm. Routine blood cultures were negative after 48 hours; however, growth was seen after 10 days. DNA probes identified the organism as belonging to the Mycobacterium avium complex.
How is it treated?
In AIDS patients: Clarithromycin/Azithromycin + Ethambutol
A 23 year old AIDS patient had fever, night sweats, fatigue and diarrhea for the past 3 months. Over that time, she has lost 22 pounds and is short of breath. Her CD4 count has been below 50/cmm for the past 6 months and her viral load is 55,000/cmm. Routine blood cultures were negative after 48 hours; however, growth was seen after 10 days. DNA probes identified the organism as belonging to the Mycobacterium avium complex.
Could the infection have been prevented in this patient?
AIDS: yes - prophylaxis with Clarithromycin or Azithromycin when CD4 count falls < 50/cmm
A 42-year old male with AIDS develops neurologic signs.
What are some infectious causes of neurologic signs in AIDS patients?
AIDS dementia complex (ADC)
Cryptococcal meningitis
Toxoplasma gondii encephalitis
Progressive multifocal leukoencephalopathy (JCV)
A 42-year old male with AIDS develops neurologic signs. The patient was brought to his physician’s office by a friend who reports progressive confusion developing over the past 6 weeks. The patient has become increasingly forgetful. Over the past week, he has developed progressive weakness on the right side of his body (Hemiparesis). CSF exam was normal. PCR of CSF found DNA of JC virus.
What does this patient have in addition to JCV? What symptom(s) clues you in to this diagnosis? What other symptoms might the patient exhibit?
PML - progressive multifocal leukoencephalopathy - hemiparesis
Insidious onset of focal symptoms including behavioral, speech, cognitive, moor, and visual impairment due to focal areas of demyelination throughout the brain.
What virus causes a common latent infection, has a seroprevalence rate among adults > 90%, is not associated with disease in healthy people, and causes PML in profoundly T cell suppressed individuals?
JC Virus
A 23-year old AIDS patient developed a fever, severe headache, stiff neck, nausea and vomiting. A CSF exam revealed slightly elevated protein, slightly decreased glucose and 10 WBC per ul. Yeast were seen in an India ink stain. What is the most likely diagnosis?
Cryptococcus neoformans
Yeast on India ink stain
A 23-year old AIDS patient developed a fever, severe headache, stiff neck, nausea and vomiting. A CSF exam revealed slightly elevated protein, slightly decreased glucose and 10 WBC per ul. Yeast were seen in an India ink stain.
Where is this organism found in nature?
Associated with dried pigeon droppings
A 23-year old AIDS patient developed a fever, severe headache, stiff neck, nausea and vomiting. A CSF exam revealed slightly elevated protein, slightly decreased glucose and 10 WBC per ul. Yeast were seen in an India ink stain.
How did he become infected?
Enters through inhalation, evades phagocytosis and Th1 cell responses, enters blood, disseminates to meninges and other tissues
A 23-year old AIDS patient developed a fever, severe headache, stiff neck, nausea and vomiting. A CSF exam revealed slightly elevated protein, slightly decreased glucose and 10 WBC per ul. Yeast were seen in an India ink stain.
What are important virulence factors of this organism?
Produces a thick polysaccharide capsule once inhaled
A 23-year old AIDS patient developed a fever, severe headache, stiff neck, nausea and vomiting. A CSF exam revealed slightly elevated protein, slightly decreased glucose and 10 WBC per ul. Yeast were seen in an India ink stain.
How is this infection diagnosed?
Detection of capsular polysaccharide antigen in serum or CSF, confirmed with growth on Sabouraud’s agar or Heart Brain infusion agar.
A 23-year old AIDS patient developed a fever, severe headache, stiff neck, nausea and vomiting. A CSF exam revealed slightly elevated protein, slightly decreased glucose and 10 WBC per ul. Yeast were seen in an India ink stain.
What is the treatment?
Amphotericin B + Flucytosine
Maintenance with Fluconazole until CD4 cells increase > 100 for > 6 months
An AIDS patient from southeast Missouri presents with persistent high grade fever, weight loss. Physical exam revealed hepatosplenomegaly, mucocutaneous ulcers in the mouth and skin lesions. An ELISA done on serum and urine for Histoplasma antigen was positive. Culture of the skin lesions on Sabouraud’s agar grew Histoplasma capsulatum after 4 weeks.
What was the source of this infection?
Endemic mycosis
Found in Ohio, Missouri, and Mississippi River Valleys
Found in soil contaminated with bird and bat droppings
An AIDS patient from southeast Missouri presents with persistent high grade fever, weight loss. Physical exam revealed hepatosplenomegaly, mucocutaneous ulcers in the mouth and skin lesions. An ELISA done on serum and urine for Histoplasma antigen was positive. Culture of the skin lesions on Sabouraud’s agar grew Histoplasma capsulatum after 4 weeks.
Describe the pathogenesis of disseminated histoplasmosis.
Most likely the result of a prior infection
Fungi once contained in lung granulomas were able to replicate and disseminate following immune suppression
Spreads throughout body
Can be isolated from many tissues
Fatal if not treated
An AIDS patient from southeast Missouri presents with persistent high grade fever, weight loss. Physical exam revealed hepatosplenomegaly, mucocutaneous ulcers in the mouth and skin lesions. An ELISA done on serum and urine for Histoplasma antigen was positive. Culture of the skin lesions on Sabouraud’s agar grew Histoplasma capsulatum after 4 weeks.
Who is at risk for disseminated histoplasmosis?
Patients with profound T cell immune suppression
An AIDS patient from southeast Missouri presents with persistent high grade fever, weight loss. Physical exam revealed hepatosplenomegaly, mucocutaneous ulcers in the mouth and skin lesions. An ELISA done on serum and urine for Histoplasma antigen was positive. Culture of the skin lesions on Sabouraud’s agar grew Histoplasma capsulatum after 4 weeks.
What other clinical manifestations are caused by H. capsulatum?
Initial infection in healthy person - flu-like illness
Chronic pulmonary histoplasmosis (patients with underlying pulmonary disease) - organism does not get walled off effectively, which can lead to cavitations and hemoptosis
An AIDS patient from southeast Missouri presents with persistent high grade fever, weight loss. Physical exam revealed hepatosplenomegaly, mucocutaneous ulcers in the mouth and skin lesions. An ELISA done on serum and urine for Histoplasma antigen was positive. Culture of the skin lesions on Sabouraud’s agar grew Histoplasma capsulatum after 4 weeks.
How should patient be treated?
If overwhelming, disseminated - Amphotericin B with maintainance with Itraconazole until/if sustained improvement in CD4 numbers and viral load
Musculocutaneous ulcers in the mouth; skin lesion due to Histoplasma
A 36 year old AIDS patient developed fever and shortness of breath. Since his last medical exam, his CD4 count has dropped to 120/cmm and his viral load has risen to 165,000/cmm. A bronchoalveolar levage specimen stained with methenamine silver revealed trophozoites and cysts.
With what is he infected?
Pneumocystis jiroveci
A bronchoalveolar levage specimen stained with methenamine silver revealed trophozoites and cysts.
Pneumocystis jiroveci
A 36 year old AIDS patient developed fever and shortness of breath. Since his last medical exam, his CD4 count has dropped to 120/cmm and his viral load has risen to 165,000/cmm. A bronchoalveolar levage specimen stained with methenamine silver revealed trophozoites and cysts.
What kind of organism is this?
Fungus
A 36 year old AIDS patient developed fever and shortness of breath. Since his last medical exam, his CD4 count has dropped to 120/cmm and his viral load has risen to 165,000/cmm. A bronchoalveolar levage specimen stained with methenamine silver revealed trophozoites and cysts.
What is the source of the organism?
Source has not been definitively identified.
May be acquired by inhalation of airborne cysts
Most individuals acquire the organism early in childhood
A 36 year old AIDS patient developed fever and shortness of breath. Since his last medical exam, his CD4 count has dropped to 120/cmm and his viral load has risen to 165,000/cmm. A bronchoalveolar levage specimen stained with methenamine silver revealed trophozoites and cysts.
Describe the pathogenesis of this organism.
Pneumocystis jiroveci
Extracellular pathogen controlled by pphagocytic macrophages - enters lung of T cell immune-suppressed individuals - replicates in surfactant - damages basement membrane during proliferation, altering permeability & reducing O2 exchange
A 36 year old AIDS patient developed fever and shortness of breath. Since his last medical exam, his CD4 count has dropped to 120/cmm and his viral load has risen to 165,000/cmm. A bronchoalveolar levage specimen stained with methenamine silver revealed trophozoites and cysts.
How can he be treated?
Pneumocystis jiroveci
TMP/SMX for treatment and maintenance
A 36 year old AIDS patient developed fever and shortness of breath. Since his last medical exam, his CD4 count has dropped to 120/cmm and his viral load has risen to 165,000/cmm. A bronchoalveolar levage specimen stained with methenamine silver revealed trophozoites and cysts.
Could this infection have been prevented?
Pneumocystis jiroveci
Yes - prophylactice treatment with TMP/SMX with CD4 count falls below 200/ul.
A 10 year old boy developed leukemia for which he was given induction cancer chemotherapy. About a week after chemotherapy began, he developed diarrhea and painful mouth ulcers. Induction chemotherapy lead to remission and the child was placed on maintenance chemotherapy. During this time, his neutrophil count dropped below 500/ul for several weeks and he developed a fever with no localizing signs.
What is a localizing sign and why are they lacking in his case?
They’re due to inflammatory responses. he has very low neutrophils, thus has poor acute inflammatory responses.
A 10 year old boy developed leukemia for which he was given induction cancer chemotherapy. About a week after chemotherapy began, he developed diarrhea and painful mouth ulcers. Induction chemotherapy lead to remission and the child was placed on maintenance chemotherapy. During this time, his neutrophil count dropped below 500/ul for several weeks and he developed a fever with no localizing signs.
What are the causes of fever in a neutropenic cancer patient?
Cancer
Cancer chemotherapy
A 10 year old boy developed leukemia for which he was given induction cancer chemotherapy. About a week after chemotherapy began, he developed diarrhea and painful mouth ulcers. Induction chemotherapy lead to remission and the child was placed on maintenance chemotherapy. During this time, his neutrophil count dropped below 500/ul for several weeks and he developed a fever with no localizing signs.
What are possible causes for infection?
Neutropenia < 7 days - Staph, Strep, Pseudomonas, E. coli, Klebsiella
Neutropenia > 10 days - bacterial & fungal - Aspergillus, Candida
A 10 year old boy developed leukemia for which he was given induction cancer chemotherapy. About a week after chemotherapy began, he developed diarrhea and painful mouth ulcers. Induction chemotherapy lead to remission and the child was placed on maintenance chemotherapy. During this time, his neutrophil count dropped below 500/ul for several weeks and he developed a fever with no localizing signs. The boy was hospitalized. Blood and urine cultures were taken and the patient was started empirically on broad spectrum IV antibiotics.
What would you recommend?
Broad spectrum antibiotic - Ceftazidime or Cefepime; Carbapenem if extended-spectrum beta-lactamase-producing organisms are a problem in the area
Anti-fungal - Caspofungin
A 10 year old boy developed leukemia for which he was given induction cancer chemotherapy. About a week after chemotherapy began, he developed diarrhea and painful mouth ulcers. Induction chemotherapy lead to remission and the child was placed on maintenance chemotherapy. During this time, his neutrophil count dropped below 500/ul for several weeks and he developed a fever with no localizing signs. The boy was hospitalized. Blood and urine cultures were taken and the patient was started empirically on broad spectrum IV antibiotics. Candida albicans was isolated on Sabourauds agar from the boy’s blood.
What kind of organism is this, and how did he become infected?
Opportunistic yeast
Found as commensals on skin & mucous membranes
Causes infection due to: T cell immune suppression, antibiotic therapy, anticancer therapy, neutropenia
What are some disease associations of Candida?
Thrush
Vaginal yeast infections
Esophagitis
Candidemia
Hepatosplenic candidiasis
What are treatment options for candidemia?
Echinocandins (caspofungin)
Fluconazole
Voriconazole
Amphotericin B
A 52 year old AIDS patient with a CD4 count of 15 developed neurological symptoms. What are the causes of neurological symptoms in AIDS patients?
CNS lymphoma
AIDS dementia complex
Cryptococcal meningitis
Toxoplasma gondii encephalitis
Progressive multifocal leukoencephalitis
CMV encephalitis
A 52 year old AIDS patient with a CD4 count of 15 developed neurological symptoms. What are the causes of neurological symptoms in AIDS patients? An MRI revealed scattered ring-enhancing lesions.
What are these lesions associated with?
Lymphoma
Toxoplasmosis
Cryptococcosis
A 52 year old AIDS patient with a CD4 count of 15 developed neurological symptoms. What are the causes of neurological symptoms in AIDS patients? An MRI revealed scattered ring-enhancing lesions. After 3 days of hospitalization, the patient died. An autopsy revealed the following: Grossly, the brain was edematous and showed areas of hemorrhagic necrosis. Microscopic examination of brain tissue revealed areas of necrosis and tissue cysts.
Can this infection be treated?
Treatment - 3 drug combination
Pyrimethamine
Sulfadiazine
Leukovorin
If intolerant of sulfa drugs, prescribe Clindamycin alongside Pyrimethamine
A 52 year old AIDS patient with a CD4 count of 15 developed neurological symptoms. What are the causes of neurological symptoms in AIDS patients? An MRI revealed scattered ring-enhancing lesions. After 3 days of hospitalization, the patient died. An autopsy revealed the following: Grossly, the brain was edematous and showed areas of hemorrhagic necrosis. Microscopic examination of brain tissue revealed areas of necrosis and tissue cysts.
Can this be prevented?
Prevention in AIDS patients:
TMP/SMX when CD4 count falls below 200
A 52 year old AIDS patient with a CD4 count of 15 developed neurological symptoms. What are the causes of neurological symptoms in AIDS patients? An MRI revealed scattered ring-enhancing lesions. After 3 days of hospitalization, the patient died. An autopsy revealed the following: Grossly, the brain was edematous and showed areas of hemorrhagic necrosis. Microscopic examination of brain tissue revealed areas of necrosis and tissue cysts.
Who else is at risk for toxoplasmosis?
Healthy children & adults - mono-like syndrome
Infants born to infected-during-pregnancy mothers - MAJOR neurological development issues
Patients with severe T cell immune suppression other than AIDS
An ultrasound preformed on a pregnant woman in her 16th week of gestation showed her fetus to have hydrocephalis and intracranial calcifications. The mother was tested and found to have IgM antibodies to Toxoplasma gondii.
What kind of organism is Toxoplasma gondii?
Protozoan
An ultrasound preformed on a pregnant woman in her 16th week of gestation showed her fetus to have hydrocephalis and intracranial calcifications. The mother was tested and found to have IgM antibodies to Toxoplasma gondii.
How may the mother have become infected?
Cleaning the litter box
An ultrasound preformed on a pregnant woman in her 16th week of gestation showed her fetus to have hydrocephalis and intracranial calcifications. The mother was tested and found to have IgM antibodies to Toxoplasma gondii.
What are the manifestations at birth and the long term sequelae of congenital toxoplasmosis?
At birth, most commonly see:
Hydrocephalis, Intracranial calcifications, Chorioretinitis
Long term, see:
Deafness, visual impairment, learning disabilities
An 83 year old woman was hospitalized with profuse, non-bloody, watery diarrhea with nausea, vomiting and lower abdominal cramping. Oocysts stained with a acid-fast stain were detected in a stool sample. Cryptosporidium antigens were detected in stool by ELISA.
What is this organism?
Sporozoite protozoan
An 83 year old woman was hospitalized with profuse, non-bloody, watery diarrhea with nausea, vomiting and lower abdominal cramping. Oocysts stained with a acid-fast stain were detected in a stool sample. Cryptosporidium antigens were detected in stool by ELISA.
How was she potentially infected?
Ingestion of contaminated water or food
Outbreaks have happened due to contaminated water in pools and water parks (not susceptible to chlorination)
An 83 year old woman was hospitalized with profuse, non-bloody, watery diarrhea with nausea, vomiting and lower abdominal cramping. Oocysts stained with a acid-fast stain were detected in a stool sample. Cryptosporidium antigens were detected in stool by ELISA.
Who is at risk for serious disease?
Immune suppressed
Infants
Elderly
An 83 year old woman was hospitalized with profuse, non-bloody, watery diarrhea with nausea, vomiting and lower abdominal cramping. Oocysts stained with a acid-fast stain were detected in a stool sample. Cryptosporidium antigens were detected in stool by ELISA.
How would you perform a diagnosis?
Finding oocytes in stool
Requires use of acid fast stain
ELISA tests for antigen detection; PCR test also available
An 83 year old woman was hospitalized with profuse, non-bloody, watery diarrhea with nausea, vomiting and lower abdominal cramping. Oocysts stained with a acid-fast stain were detected in a stool sample. Cryptosporidium antigens were detected in stool by ELISA.
What treatment would you use?
Nitazoxanide - immunocompetent
Adjustments to anti-HIV drugs - AIDS patients
Paromomycin - used with some success in immunocompromised, although generally there is no treatment
A 54 year old man from rural Georgia was being treated for leukemia with a regimen that included corticosteroids when he developed acute, severe abdominal pain. This was accompanied by nausea, vomiting and diarrhea that was occasionally bloody. Test for bacterial and viral causes of gastroenteritis were negative, however, larvae of Strongyloides stercoralis were found on microscopic examination of the stool.
Who is at risk of catching this?
Persons living in or visiting endemic areas, including SE US & Appalachian region, tropical & subtropical areas
A 54 year old man from rural Georgia was being treated for leukemia with a regimen that included corticosteroids when he developed acute, severe abdominal pain. This was accompanied by nausea, vomiting and diarrhea that was occasionally bloody. Test for bacterial and viral causes of gastroenteritis were negative, however, larvae of Strongyloides stercoralis were found on microscopic examination of the stool.
What can chronic infections lead to?
Disseminated infections if patient becomes immuno-suppressed
A 54 year old man from rural Georgia was being treated for leukemia with a regimen that included corticosteroids when he developed acute, severe abdominal pain. This was accompanied by nausea, vomiting and diarrhea that was occasionally bloody. Test for bacterial and viral causes of gastroenteritis were negative, however, larvae of Strongyloides stercoralis were found on microscopic examination of the stool.
Describe the pathogenesis of this organism.
Parasites escape from GIT in circulation (often bringing along bacteria) - larvae invade CNS, heart, urinary tract, endocrine glands
A 54 year old man from rural Georgia was being treated for leukemia with a regimen that included corticosteroids when he developed acute, severe abdominal pain. This was accompanied by nausea, vomiting and diarrhea that was occasionally bloody. Test for bacterial and viral causes of gastroenteritis were negative, however, larvae of Strongyloides stercoralis were found on microscopic examination of the stool.
How would you treat this?
Thiabendazole
