ID Diagnosis Flashcards
What are the tests to diagnose HIV?
4th gen ELISA
confirm w/ western blot
PCR
What does HIV primary infection look like?
Fever, malaise, N/V/D, maculopapular rash, neuro sx
What labs do you want to monitor for HIV?
every 3-6 mo monitor:
CD4 cell count and HIV RNA
CBC
Chemistries
Liver, kidney, lipids, fasting glucose, HbA1c
Annual STIs, Hep B, C, HSV and cancer
Classic triad of RMSF
Classic triad: fever, headache & rash
Incubation of RMSF
2-14 d
Rash beings on ankles/wrists, palms/soles, spreads centrally, maculopapular, bit by tick
RMSF
What would labs for RMSF show?
eukopenia, thrombocytopenia
small painful ulcers on an erythematous base
HSV-1 & 2
large, shallow ulcers
CMV
ulcerations with exudate at
the base
Aphthous stomatitis
Kaposi’s sarcoma
associated w/ herpes virus
ca of enfothelium
Bacillary angiomatosis causative organism
Bartonella henselae
How is malaria transmitted?
Transmitted by female mosquito (Anopheles) → humans (intermediate host)
Can be transmitted via blood or to fetus but more rare
Epidemiology of malaria
MC Africa
South America
Malaria-endemic areas develop resistance to clinical dz slowly w/ age (quicker w/ higher intensity
*Resistance is to clinical manifestation NOT infection
Pregnant women more susceptible and lose resistance to infection
What to look for in labs if concerned about malaria
Anemia (Hgb <13)
Thrombocytomepia (<100K)
Leukopenia
↑ AST and ALT
↑ Creatinine
Microscopy- blood thin (species) & thick smears
Rapid Diagnostic Test
PCR
What type of malaria is the main cause of severe clinical malaria and death?
Plasmodium falciparum
How often is fever present for P vivax and P ovale?
every 2 days
How often is fever present for P malariae
every 3 days
What patient population is protected from P. vivax and why?
Duffy Ag absent in West African populations
Pts must have duffy antigen on their RBC in order for P. vivax to bind and invade
Where is Babesiosis MC seen?
New England, Wisconsin & Minnesota
What is the parasite that causes Babesiosis?
B. microti
How is Babesiosis transmitted?
Tick Ixodes scapularis (same as lyme)
*requires >24 hr of attachment
Can also be transmitted via blood transfusion
Microscopic exam of blood → “Maltese cross” pattern
Flu-like illness- fever, chills, fatigue, HA (lasting wks to mo)
Babesiosis
May be asymptomatic in children
Loose, foul-smelling stools
Steatorrhea (fat malabsorption)
Cramping, bloating, nausea
Anorexia, malaise, weight loss
No blood in stool
Chronic: steatorrhea, growth impairment
Giardia Intestinalis
How is Giardia Intestinalis transmitted?
drink contaminated fresh water (beaver fever)
1-4 wk incubation
Gradual onset
Liver abscess → sx >4 wk, fever, abd pain, hepatomegaly, jaundice, cough due to diaphragm irritation
Amebic dysentery and colitis - fever w/ bloody diarrhea, cramping, abd pain, weight loss
Amoebiasis
Amoebiasis etiology
Entamoeba histolytica
Amoebiasis transmission
Fecal oral transmission
Invades mucosa of large intestine and thickness of intestinal wall → perforation or peritonitis and can get into blood stream→
If gets into portal circulation goes to liver
Watery diarrhea
Dehydration, weight loss, abd pain, N/V
Cryptosporidiosis
Cryptosporidiosis peak seasons
late summer and early fall
Cryptosporidiosis transmission
Outbreaks in day care centers
Zoonotic transmission: farmers and animal handlers
Waterborne infection: swimming pools, public drinking water
Winterbottom’s sign: posterior cervical adenopathy
Intermittent fever: due to antigenic variation
CNS involvement:
Diurnal somnolence, nocturnal insomnia, constant HA, behavior changes→ DEATH
Gambial HAT → mo to years
Rhodesian HAT→ wks to mo
Human African Trypanosomiasis (HAT)
“Sleeping Sickness”
Human African Trypanosomiasis (HAT) epi and eti
sub-Saharan Africa
Trypanosoma brucei gambiense (West African)
Trypanosoma brucei rhodesiense (East African)
How is Human African Trypanosomiasis (HAT) tranmitted?
Transmitted to human by Tsetse flies
Chagoma: indurated lesion at site of parasite entry
Romaña’s sign when conjunctiva is port of entry
Fever, facial edema
Severe myocarditis w/ ECG changes
Chronic: dilated, megacolon, cardiomyopathy
Chagas Disease
How is Leishmaniasis transmitted?
Sandfly Vector
Fever, weight Loss
Hepatosplenomegaly
Pancytopenia
Hypergammaglobulinemia
Hyperpigmentation (“Black Fever”)
Kala-azar
Visceral Leishmaniasis (VL)
Kala-azar
Visceral Leishmaniasis (VL) etiology
L. donovani (Asia-Africa
L. infantum (southern Europe)
L. chagasi (Brazil)
Mucocutaneous Leishmaniasis (ML) etiology
L. braziliensis (Central/South America)
What type of endocarditis is most likely to have peripheral manifestations?
Subacute Bacterial Endocarditis
What are peripheral manifestations of infectious endocarditis?
conjunctival petecchiae
splinter hemorrhages
Osler’s nodes (pain, fingers and toes)
Janeway lesions (macules on palms and soles)
Roth’s spots (retinal hemorrhages)
What pt pop is most likely to get SBE and what is the etiology of it?
Pts who recently had dental procedure or who have underlying valve abnormality
MC = Viridans Streptococci (part of oral flora)
What pt pop is most likely to get ABE and what is the etiology?
MC w/ IVDU
S. aureus**
What type of bacteria is most likely to be the cause of Cx neg endocarditis and why?
Coxiella burnetti or Chlamydia psittaci bc it doesnt grow well for cx
What bacteria is most likely the cause of prosthetic valve endocarditis if presentation is <60 days from surg?
S. aureus or S. epidermidis
What bacteria is most likely the cause of prosthetic valve endocarditis if presentation is >60 days from surg?
viridans streptococci
What valves are MC involved in infective endocarditis?
Mitral MC then aortic
Tricuspid MC in IVDU
What bacteria is associated w/ high morbidity w/ CHF and emboli?
Coag neg staph → S. lugdunensis
Pathogenesis of NBTE
Endothelial cell damage, hypergoagulability (less common in US)
RF: valvular dz, malig, CT d/o, intracardiac catheter, prolonged febrile illness, persistent fetal circulation
Pathogenesis of Transient bacteremia
MC in US Turbulent flow → high pressure flow, structural abnormality (regurg or narrow) and bacteremia (valvular adherence)
What baseline labs should you get for pt presenting w/ fever and neutropenia?
CBC
Liver and renal function tests
Urinalysis, blood and urine culture
CXR
What pt pop is at risk for Neutropenia and Defects in Phagocytic Defenses?
Post chemotherapy or other myelosuppressive therapy, bone marrow transplant recipients, acute leukemics
Risk of infection is significant at ANC <500
What pt pop is at risk for infections due to defects in Cellular Immunity?
Pts w/ AIDs, Hodgkin’s lymphoma, monoclonal Ab therapy and LT corticosteroid use
Infection due to opportunistic pathogens
What pt pop is at risk for infections due to Defects in Humoral Immunity?
Pts w/ gammaglobulinemia, Multiple Myeloma, CLL with hypogammaglobulinemia, splenectomized patients, sickle cell disease
what organisms are pts w/ Pts w/ gammaglobulinemia, Multiple Myeloma, CLL with hypogammaglobulinemia, splenectomized patients, sickle cell disease at risk for?
Offending organisms are encapsulated, pyogenic bacteria: S. pneumoniae, H. influenzae
What infections is HIV pt w/ CD4 <100 at risk for?
Cryptococcal Infections MAI CMV Toxoplasma Cryptosporidium
What infections is HIV pt w/ CD4 <200 at risk for?
PJP
What is qSOFA criteria?
RR>22, AMS, SBP <100 mmHg
qSOFA ≥ 2 IDs pts w/ suspected infection who are likely to have a prolonged ICU stay or to die in the hospital
What type of bacteria is most likely to cause sepsis and why?
Endotoxin bacteria more likely to cause sepsis (due to cell wall component on gram negs)
Pathophys of sepsis
Life-threatening organ dysfn caused by a dysreg host response to infection
Bacteria invade tissue → macrophages are triggered and released causing pro and antiinflam mediators to respond
Sepsis occurs when proinflam mediators > anti and they exceed the boundaries of the local enviro
MC cause of septic shock
“Any source of infection→ MC is pneumo, intra-abd infection, UTI bacteremia
MC G neg: E.Coli, Klebsiella, pseudomonas, enterobacter
MC G pos: Staph aureus, Strep pneumo
MC Fungi: candida”
Define septic shock
Sepsis w/ circulatory and cellular/metabolic abnormalities profound enough to substantially ↑ mortality
(type of distributive shock bc of hypotension)
Criteria for septic shock
At least 1 of the following:
Persistent hypotension after fluid resuscitation and requiring vasopressors to maintain MAP >65 mmHg
Serum lactate level >2 mmol/L
W/u for septic shock
ID infection source: PE, blood cx, urine cx, resp cx, CXR, CT
CBC, CMP, LFT, coags, lactate, ABG
Assess preload (CVP, US)
What do you expect to see on w/u for DIC?
PT/INR ↑ (extrinsic coagulation factors)
aPTT ↑ (intrinsic coagulation factors)
Fibrinogen ↓ (can be high during early sepsis)
D-Dimer ↑
Platelets ↓ (Thrombocytopenia)
