Case vingette or key clues/Causal organisms and/or diagnosis Flashcards by Tariq Ziad

Furuncles or carbuncles on neck, face, axilla, buttocks

S. aureus

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Furuncles or carbuncles with follicles from neck down

P. aeruginosa (hot tub folliculitis)

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Inflammation of follicles & sebaceous glands

Propionibacterium acnes (acne vulgaris)

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Initially vesicular; skin erosion; “honey crusted” lesions; catalase -ve

S. pyogenes (impetigo)

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Initially vesicular with long lasting bullae; catalase +ve

S. aureus (impetigo)

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Vesicular lesions that sometimes preceded by neurologic pain

Herpes

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Solitary or lymphocutaneous lesions, rose gardeners or florists, sphagnum moss

Sporothrix schenckii (rose gardener disease)
Mycetoma (swelling with pain, sinus tract formation, yellow granules in exudate)

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Subcutaneous swelling (extremities & shoulders)

Mycetoma (swelling with pain, sinus tract formation, yellow granules in exudate)
Bacteria: actinomyces, nocardia
Fungi: Madurella, Pseudallescheria, Sporothrix

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Jaw area, associated with carious teeth, dental extraction, or trauma

Actinomyces israelii “lumpy jaw”

Mycetoma (swelling with pain, sinus tract formation, yellow granules in exudate)

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Pustule with dark red fluid-filled, tumor-like lesion that lead to necrosis & black eschar surrounded by red margin

Malignant pustule

Bacillus anthracis, & Pseudomonas septicemia (ecthyma gangrenosum)

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Blue-green pus, grape-like odor, burns

P. aeruginosa (cellulitis)

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Dermal pain, edema, heat & rapid spread.

Red, raised butterfly facial rash

S. pyogenes [Erysipelas] (cellulitis)

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Hot inflamed tissues. Deeper tissues from extension of skin lesions or wounds including surgical

S. aureus, S. pyogenes, gram (-ve) rods, Clostridium & anaerobes (cellulitis)

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Surgical wounds (clean)

S. aureus

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Surgical wound (dirty)

S. aureus, Enterobacteriaceae, anaerobes

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Trauma wounds

Clostridium, Enterobacteriaceae, Pseudomonas

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Shallow puncture wound through tennis shoe sole

P. aeruginosa

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Various animal bites

Pasteurella multocida

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Human bites, fist fights

Eikenella corrodens

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Dog bites

Capnocytophaga canimorsus

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Rat bites

Streptobacillus moniliformis & Spirillum minus

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Cat scratches resulting in lymphadenopathy with stellate granulomas

Bartonella henselae

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Red, bulging tympanic membrane, fever 102-103 F; pain goes away if drum ruptures or if ear tubes are patent

Acute otitis media:
S. pneumoniae
H. influenzae (often nontypeable, recurs)
Moraxella catarrhalis
RSV
Rhinovirus

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Ear pain

Otitis externa (often mixed infections):
S. aureus (NF)
Candida albicans (NF)
Proteus (water organism)
Pseudomonas (water)

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Severe ear pain in diabetic; life threatening

P. aeruginosa (malignant otitis externa)

Sinus pain; low grade fever

``` Sinusitis: S. pneumoniae H. influenzae (often nontypeable, recurs) Moraxella catarrhalis RSV Rhinovirus ```

Painful mouth; overgrowth of spirochetes & fusiform bacteria

Fusobacterium & treponemes (normal oral spirochetes)

Sore mouth with thick white coating (painful red base under); increased risk: premature infants, AIDS, IC patients, patients on antibiotics, vitamin C deficiency

Candida

Inflamed tonsils/pharynx, which may be purulent & may develop abscesses; cervical lymphadenopathy, fever, stomach upset; sandpaper rash

Sore throat: S. pyogenes (group A), rash indicates presence of erythrogenic exotoxin A

White papules with red base on posterior palate & pharynx, fever

Coxsackie A

Throat looking like Strep with severe fatigue, lymphadenopathy, fever, rash; heterophile (+ve); Downey type II cells

Epstein-Barr virus

Low grade fever with a 1-2 day gradual onset of membranous nasopharyngitis &/or obstructive laryngotracheitis; bull neck from lymphadenopathy; elevated BUN; abnormal ECG; little change in WBC (toxin). Exudate bleeds profusely when dislodged

Corynebacterium diphtheriae (diphtheria)

Rhinitis, sneezing, coughing

``` Common cold: Rhinoviruses (summer-fall) Coronaviruses (winter-spring) Human metapneumovirus Adenovirus, & many others ```

Bilateral eyelid swelling, > 10% eosinophilia, fever, muscle pain, earlier GI symptoms

Trichinella

Stye

S. aureus | Propionibacterium acnes

Unilateral inflammation at bite site often around the eye or mouth; travel to Mexico, Central or South America

Trypanosoma cruzi

Red itchy eye(s)/pus; onset 2-5 days in neonates

Bacterial pink eye (conjunctivitis)

Red itchy eye(s)/pus; onset 5-10 days in neonates

Conjunctivitis: Neisseria gonorrhoeae, Chlamydia trachomatis (serotypes D-K U.S.)

Neonate with "sticky eye"

S. aureus

Red, itchy eye(s), thin exudate; pain, photophobia

Viral pink eye: adenovirus (more common than bacterial pink eye)

Red eye, pus

S. aureus, group A Strep, Strep pneumoniae (all gram [+]), H. influenzae, H. aegypticus

Red eye, pus, presence of inclusion bodies in scraping

Chlamydia trachomatis serotypes D-K (inclusion conjunctivitis)

Granulomas & inturned eye lashes, corneal scarring, blindness

Chlamydia trachomatis serotypes A, B, Ba, C (trachoma)

Chorioretinitis in neonates or AIDS

Toxoplasma, CMV

Retinopathy with keratitis in baby of an IV drug abuser mother

Treponema pallidum (congenital syphilis)

Acute endocarditis in IV drug user

S. aureus

Acute endocarditis in non IV drug user

S. aureus

Subacute endocarditis in patients with poor oral hygiene or dental work

Viridans streptococci (55% of cases in native hearts)

Subacute endocarditis with gram -ve (normal oral flora)

``` HACEK organisms: Haemophilus aphrophilus Actinobacillus actinomycetemcomitans Cardiobacterium hominis Eikenella corrodens Kingella kingae ```

Subacute endocarditis in biliary or urinary tract infection, & GU manipulation inn elderly men

Enterococcus faecalis

Subacute endocarditis in IV drug user

``` S. epidermidis Aspergillus (branching <45) Candida (pseudohyphae) Pseudomonas Viridans streptococci ```

Dilated cardiomyopathy in rural South America

Trypanosoma cruzi

Inflamed epiglottis; patients often 2-3 years & unvaccinated, thumb sign on x-ray

H. influenzae type b (Hib) (epiglottitis)

Infant with fever, sharp barking cough, inspiratory stridor, hoarse phonation

Parainfluenza virus (croup)

Wheezy; infant or child < or = 5 years

RSV (bronchitis)

Wheezy; > 5 years

Bronchitis: | H. influenzae, M. pneumoniae, Chlamydophila pneumoniae

Wheezy; > 9 years, afebrile, with cough > 2 weeks

Bordetella pertussis

Typical pneumonia in poorly nourished, unvaccinated baby/child; giant cell pneumonia with hemorrhagic rash

Measles: malnourishment increase the risk of pneumonia & blindness

Typical pneumonia in adults (including alcoholics), rusty sputum, often follows influenza

Streptococcus pneumoniae

Typical pneumonia in neutropenic patients, burn, CGD, & CF

Pseudomonas

Typical pneumonia with foul smelling sputum, aspiration possible

Anaerobes, mixed infection (Bacteroides, Fusobacterium, Peptococcus)

Typical pneumonia in alcoholics, abscess formation, aspiration, facultative anaerobe, gram -ve bacterium with huge capsule, currant jelly sputum

Klebsiella pneumoniae

Typical pneumonia, nosocomial, ventilator, post-influenza, abscess formation, gram +ve, catalase +ve, coagulase +ve, salmon colored sputum

S. aureus

Atypical pneumonia in teens/young adults; bad hacking cough; initially non-productive color

Mycoplasma pneumoniae (most common cause of pneumonia in school age children)

Atypical pneumonia with air conditioning exposure especially > 50 years of age, heavy smoker, drinker

Legionella spp.

Atypical pneumonia with bird exposure, hepatitis

Chlamydophila psittaci

Atypical pneumonia in AIDS patients with staccato cough; "ground glass" x-ray; biopsy: honeycomb exudate with silver staining cysts, progressive hypoxia

Pneumocystis jiroveci

ARDS with history of travel to Far East, winter, early spring, hypoxia

SARS-CoV

ARDS in spring, 4 corner region, exposure to rodents

Hanta virus

Acute pneumonia or chronic cough with weight loss, night sweating, calcifying lesions, over 55 years, HIV +ve, or immigrant from developing country

M. Tuberculosis

Acute pneumonia or chronic cough with weight loss, night sweating, calcifying lesions, dusty environment with bird or bat fecal contamination (Missouri chicken farmers), yeasts packed into phagocytic cells

Histoplasma capsulatum

Acute pneumonia or chronic cough with weight loss, night sweating, calcifying lesions, desert sand, SW U.S.

Coccidioides immitis

Acute pneumonia or chronic cough with weight loss, night sweating, calcifying lesions, rotting contaminated wood, North & South Carolina

Blastomyces dermatitidis

Urethritis with gram -ve diplococci in PMNs in urethral exudate

Neisseria gonorrhea

Urethritis with -ve culture & inclusion bodies

Chlamydia trachomatis

Urethritis with urease +ve & no cell wall organism

Ureaplasma urealyticum

Urethritis with flagellated protozoan with corkscrew motility

Trichomonas vaginalis

Frequent & painful urination, hematuria, & fever

Cystitis: | E. coli, other gram -ve enterics, Pseudomonas, Proteus

Cystitis in young; newly sexually active individual; gram +ve cocci

S. saprophyticus

Frequent & painful urination, hematuria, flank pain, & prominent fever

Pyelonephritis: | E. coli, Staphylococcus

Friable, inflamed cervix with mucopurulent discharge

Cervicitis: Neisseria gonorrheae (gram -ve diplococci) Chlamydia trachomatis (non-staining obligate intracellular parasite) Herpes simplex

Vaginal itching, pain, adherent yellowish discharge, pH>5, fishy amine odor in KOH, clue cells; gram -ve cells dominate

Bacterial vaginosis: overgrowth of Gardnerella vaginalis & anaerobers

Vaginal itching, pain, with vulval pruritis, erythema, and discharge: consistency of cottage cheese

Candida spp.

Vaginal itching, pain, with foamy, purulent discharge, many PMNs & motile trophozoites microscopically (corkscrew motility)

Trichomonas vaginalis

Adnexal tenderness, bleeding, deep dyspareunia, vaginal discharge, fever; tenderness from cervical movement, possibly palpable inflammatory mass on bimanual exam, onset often follows menses

PID: Neisseria gonorrheae or Chlamydia trichomatis or both or a variety of other organisms

Genital warts

HPV (most common U.S. STD), Treponema pallidum, molluscum contagiosum

Multiple genital vesicular, painful, coalescing lesions that recur

Herpes simplex

Non-tender genital indurated ulcer healing spontaneously 2-10 weeks

Treponema pallidum

Non-indurated, painful genital papule, suppurative with adenopathy, slow to heal

Haemophilus ducreyi

Soft, painless genital ulcer, patient from Caribbean or New Guinea, gram -ve intracellular bacilli

Klebsiella granulomatis (granuloma inguinale)

Genital elephantitis with initial papule heals; lymph nodes enlarge & develop fistulas

Chlamydia trichomatis L1-L3

Genital elephantitis with microfilariae in blood stream, patient from Tropics

Wuchereria or Brugia (filarial nematodes)

Diarrhea develops 1-6 hrs after eating Ham, potato salad or cream pastries

S. aureus (Heat stable enterotoxin)

Diarrhea after eating fried rice

Bacillus cereus: emetic form (heat stable toxin causes vomiting)

Diarrhea in infants & toddlers that persists for 5-7 days

Rotaviruses

Diarrhea in young kids & IC patients

Adenovirus 40/41

Diarrhea in infants in developing countries

Enteropathogenic E. coli (adherence to enterocytes through pili causes damage to adjoining villi)

Diarrhea in older kids & adults

Norwalk virus

Diarrhea (watery) after eating beef, poultry, gravies

C. perfringens (enterotoxin)

Diarrhea (profuse watery) "rice water stool"

V. cholerae (toxin stimulates adenylate cyclase & causes increase in cAMP in small intestine without inflammation or invasion)

Diarrhea after eating raw or undercooked shellfish

V. parahaemolyticus

Diarrhea that develops 12-72 hrs after drinking water, or eating undercooked fruits or vegetables

Enterotoxigenic E. coli (heat labile toxin (LT) stimulates adenylate cyclase resulting in efflux of water & ions into small intestinal lumen)

Diarrhea after eating ham-burger with blood, but no fever

Enterohemorrhagic E.coli (verotoxin, which is a cytotoxin, causes bloody diarrhea)

Diarrhea (loose, pale, greasy) with mild to severe malabsorption syndrome after camping

Giardia lamblia (multiply & attach to intestinal villi by sucking disk)

Diarrhea (chronic severe) in AIDS or IC patients with acid fast spores/oocytes in stool

Cryptosporidium parvum, Isospora belli, Cyclospora, Microsporidia

Diarrhea (occult blood) poultry, domestic animals, water develops after 3-5 days

Campylobacter jejuni (multiply in the small intestine; invades epithelium)

Diarrhea (occult blood) poultry, domestic animals develops 8-48 hrs

Salmonella gastroenteritis (PMN & PG response, which stimulates cAMP)

Diarrhea (first watery then bloody)

Shigella (shallow mucosal ulceration & dysentery; septicemia rare)

Diarrhea wild domestic animals

Yersinia enterocolotica (difficult to distinguish from appendicitis, grow in cold)

Diarrhea associated with use of broad spectrum antibiotics (commonly clindamycin)

C. difficile

Diarrhea (bloody) in adults

Enteroinvasive E. coli

Diarrhea (bloody) with history of travel to tropical areas

Entamoeba histolytica (characteristic flask-like lesions & extra intestinal abscesses)

Hepatitis food born without chronicity, sturdy naked RNA virus

Hepatitis A (picornavirus)

Hepatitis in IV drug abuse, needle stick, chronic carrier state, cirrhosis, primary hepatocellular carcinoma; DNA virus easily inactivated by alcohol

Hepatitis B (Hepandavirus)

Hepatitis in transfusion, IV drug abuse, or prison acquired tatoos, chronic active hepatitis; enveloped RNA virus

Hepatitis C (Flavivirus)

Hepatitis enterically transmitted with high fatality in pregnant women, no chronic form

Hepatitis E (Hepevirus)

Acute abdominal pain due to intestinal blockage

Ascaris lumbricoides or Diphyllobothrium latum

Bile duct blockage

``` Ascaris lumbricoides (following surgery) Fasciola hepatica ```

Peritonitis

Bacteroides fragilis or E. coli

Cirrhosis with history of travel to Puerto Rica, Peace Corps; egg granulomas block triads leading to fibrosis

Schistosoma mansoni

Cirrhosis in IV drug use

Hepatitis viruses

Pancreatitis (generally with swelling of salivary glands)

Mumps virus

Megaloblastic anemia

Diphyllobothrium latum

Normocytic anemia

Chronic infections

Microcytic hypochromic anemia (iron deficiency anemia)

Ancylostoma, Necator, Trichuris

Decreased Hb, hematocrit with cyclic fever, often travel to tropics; rings or schizonts in RBCs

Plasmodium spp.

New England, splenectomized patient, hemolytic anemia, no history of travel, summer months (tick exposure), with multiple ring forms inside RBCs

Babesia microti

Reduced CD4 cell count

HIV

Infectious mononucleosis, Downey type II cells (reactive T cells) sore throat, lymphadenopathy, young adult, heterophile (+ve)

EBV

Infectious mononucleosis with heterophile (-ve)

CMV Toxoplasma Listeria (Listeriosis)

Unvaccinated child, hypoglycemic, lymphocytosis with paroxysmal cough, stridor on inspiration

Bordetella pertussis

Meningitis in neonates to 2 months

S. agalactiae E. coli Listeria monocytogenes

Meningitis in 3 months to 2 years; unvaccinated child

H. influenzae type B (gram -ve pleomorphic rod with polyribitol capsule)

Meningitis in 3 months to young adults. Prodrome may be very rapid; child may be properly vaccinated; rash

Neisseria meningitidis (ferments maltose)

Meningitis in less than 2 years and in young adults to elderly

S. pneumoniae

Meningitis in renal transplant patient

``` Cryptococcus neoformans (encapsulated; urease +ve yeast) Listeria monocytogenes (motile gram +ve rode) ```

Meningitis in endemic areas

``` Coccidioides (Southwestern U.S.) Histoplasma capsulatum (near U.S. great river beds with exposure to bird or bat feces) ```

Meningitis with low cell mediated immunity, nerve palsies in a patient with T.B. & low CSF glucose

M. tuberculosis

Meningoencephalitis after swimming & diving in warm waters (hot springs) prefrontal headache, high fever, disturbance of smell

Naegleria

Meningoencephalitis in IC patients

Acanthamoeba or Toxoplasma

Encephalitis summer-fall, mosquito born from bird reservoirs

Western equine encephalitis (midwest & west U.S.) St. Louis encephalitis (elderly blacks with hypertension, most severe infections) West Nile virus (North America) California encephalitis (entire U.S. & rodent reservoir) Eastern equine encephalitis

Encephalitis with focal uptake of radionucleotide, RBCs in CSF, high opening pressure, frontal & temporal lobes involvement

Herpes simplex encephalitis

Child following a viral illness with pernicious vomiting, lethargy & irritability, which may lead to brain swelling, indication of aspirin usage

Reye syndrome: | Influenza or varicella infection

Epilepsy onset after age of 20, Mexico, immigrant

Taenia solium (neurocysticercosis)

Systemic disease following bull's eye rash & may be associated with Bell palsy

Borrelia burgdorferi

Guillain-Barre with GI tract problems

Campylobacter jejuni

Guillain-Barre with respiratory problems

Influenza

Sandpaper like rash (trunk & neck to extremities)

Scarlet fever (S. pyogenes [exotoxin A-C])

Diffuse sunburn like rash (trunk & neck to extremities), with desquamation on palms & soles

Toxic shock syndrome (S. aureus [TSST-1])

Perioral erythema, bullae, vesicles, desquamation except tongue & palate (trunk & neck to extremities)

Staphylococcal skin disease: scalded skin disease (S. aureus [exofoliatin])

Petechial rash that progress to purpura (trunk to extremities), spares palms, soles, & face

Epidemic typhus (Rickettsia prowazekii [endotoxin])

Petechial rash that progress to purpura at ankles & wrists then generalized with palms & soles

Rocky Mountain spotted fever, most common on East Coast (Rickettsia rickettsii [endotoxin])

Petechial rash that progress to purpura (generalized)

Early meningococcemia (Neisseria meningitidis [endotoxin])

Generalized cutaneous maculopapular rash involving palms & soles (bronze or copper colored) & mucous membranes: condyloma

Secondary syphilis (Treponema pallidum [endotoxin])

Confluent erythematous maculopapular rash (head to entire body), Koplik spots

Measles (Rubeola virus [rash from T cell destruction of virus infected cells in capillaries])

Erythematous concentric rings (Bull's eye) with outward progression from site of tick bite

Lyme disease (Borrelia burgdorferi)

Osteomyelitis in adults, infants, & children without major trauma or special conditions

S. aureus

Osteomyelitis in neonates

S. aureus | Group B Streptococcus, gram -ve rods (E. coli, Klebsiella, Proteus, Pseudomonas)

Osteomyelitis in sickle cell anemia

Salmonella

Osteomyelitis in trauma

Pseudomonas

Arthritis in all age groups (except 15-40)

S. aureus

Arthritis in age group 15-40

N. gonorrheae

Arthritis in prosthetic joint

Coagualse -ve Staphylococci

Viral Arthritis

Rubella, Hepatitis B, & parvovirus

Arthritis (chronic onset, mono)

M. tuberculosis or fungi

Arthritis of large joint after tick bite or erythema migrans

Borrelia burgdorferi

Arthritis (post-infectious) following GI infection

``` Reactive arthritis (Reiter's syndrome): Salmonella, Shigella, Campylobacter, or Yersinia enterocolitica ```

Arthritis (post-infectious) following sexual contact

Reactive arthritis (Reiter's syndrome): Chlamydia trachomatis

Case vingette or key clues/Causal organisms and/or diagnosis Flashcards

(168 cards)