Infectious Disease - Specific Findings Flashcards
Staphylococcus aureus (S. aureus)
Gram positive cocci arranged in clusters
Catalase positive - increased susceptibility in granulomatous disease
Coagulase positive - coagulase cleaves fibrinogen to fibrin causing clotting and formation of fibrin clot around infection leading to abscess thayer
Red Man Syndrome
Drug reaction to rapid infusion of Vancomycin mediated by non-specific degranulation of mast cells; characterized by diffuse flushing / erythematous rash of the face, neck, and upper torso
Prevented with slower infusion and pre-treatment with anti-histamines
Thayer-Martin agar
AKA VPN Media
Chocolate agar plate suffused with vancomycin (inhibits gram positive organisms), polymixin (inhibits gram negative organisms except for Neisseria), and nystatin (inhibits fungi); suppresses the growth of endogenous flora while supporting growth of N. gonorrhoeae
Gold standard for diagnosis of Neisseria gonorrhoeae
Lowenstein-Jensen agar
Used to culture mycobacterium tuberculosis
Selects against gram positive bacteria in respiratory flora
MacConkey agar
Used to culture lactose-fermenting enteric bacter (E. coli, Klebsiella) commonly found in UTIs
Bordet-Gengou (Potato) agar
Used to culture Bordetella Pertussis
Erythema migrans
Red bullseye rash, specific for early phase of Lyme disease
Roth spots
Round, white spots on the retina, surrounded by hemorrhage
Associated w/ bacterial endocarditis
Janeway lesions
Small, painless, erythematous lesions on palms or soles
Associated with bacterial endocarditis
Thumbprint sign
Thickening of the epiglottis and aryepiglottic folds
Associated with epiglottitis, often caused by H. flu
UTI - Urine Labs
+ Leukocyte Esterase (Bacterial)
+ Nitrites (Gram negative)
+ Urease (Klebsiella, Proteus)
- Urease (E. coli, enterobacter)
Morulae
“Berry-like” cytoplasmic inclusions in macrophages / neutrophils
Associated with Erlichosis (Erlichia Chaffeensis infection)
Charcoal yeast extract agar
Gold standard for growth of Legionella (i.e. respiratory legionellosis / Legionnaire’s disease)
Strawberry cervix
Associated with trichomonas vaginalis
Pneumonia in neonates (< 4 weeks) - Common pathogens
Group B. Strep
E. coli
Pneumonia in children - Common pathogens
Viruses (RSV) Mycoplasma C. trachomatis (infants - 3 years) C. pneumoniae (school-aged children) S. pneumoniae
Pneumonia in adults (18-40, 40-65)) - Common pathogens
Mycoplasma
C. pneumoniae
S. pneumoniae
+ in older adults (40-65)
H. influenzae
Anaerobes
Viruses
Pneumonia in the elderly - Common pathogens
S. pneumoniae Influenza virus Anaerobes H. influenzae Gram negative rods
Black colonies on cystine-tellurite agar
Corynebacterium diptheria (gram positive rod)
HBsAg / anti-HBsAg
HBsAg = HBV surface antigen; indicates active HBV infection
Anti-HBsAg indicates immunity to HBV
HBcAg
HBcAg = HBV core antigen
Anti-HbcAg (IgM) = acute / recent infection
Anti-HbcAg (IgG) = prior / chronic infection
HbeAg
HBeAg = HBV core antigen which is a marker of active viral replication / high transmissability
anti-HbEAg - indicates low transmissability
CSF findings in Polio
Elevated WBCs, slightly elevated protein
Normal glucose
Histologic findings in chlamydia conjunctivitis
Epithelial cells of the conjunctival lining show basophilic intracytoplasmic inclusions, which are representative of the organism C. trachomatis itself
“Violin string” adhesions
Adhesions between the liver capsule and the peritoneum
Seen in “Fitz-Hugh-Curtis” syndrome - infection of the liver capsule by C. trachomatis or N. gonorrhea secondary to pelvic inflammatory disease
Common causes of meningitis - Newborn (0-6 months)
Group B streptococci
E. coli
Listeria
Common causes of meningitis - Children (6 months - 6 years)
S. pneumoniae
N. meningitidis
H. influenza
Enteroviruses (esp. Coxsackievirus)
Common causes of meningitis in adolescents and adults (6 - 60 years)
S. pneumonia
N. meningitidis (#1 in teens)
Enteroviruses
HSV-2
Common causes of meningitis in the elderly (60+)
S. pneumoniae
Gram negative rods
Listeria
Viral causes of meningitis
Enteroviruses (esp. Coxsackievirus) HSV-2 HIV West Nile Virus VZV
Pulmonary Aspergillosis - CT and culture findings
CT shows “air crescent sign” - represents the presence of air between Aspergillus-infected and normal tissue
Culture shows 45-degree branching septated hyphae with rare fruiting bodies
Most common cause of osteomyelitis - in general?
S. aureus
Most common cause of osteomyelitis - in IDUs and diabetics?
Pseudomonas
Serratia
Most common cause of osteomyelitis - in Sickle Cell Anemia?
Salmonella
Most common cause of osteomyelitis with vertebral involvement (Pott’s Disease)?
Mycobacterium tuberculosis
Most common cause of osteomyelitis with prosthetic joint involvement?
S. aureus
S. epidermidis
Most common cause of osteomyelitis in sexually active adults?
N. gonorrhea
Koplik Spots
Blue/white lesions of the buccal mucosa
Seen in primary measles infection
Cowdry A Inclusion Bodies
Seen in biopsies of Varicella Zoster (Shingles) lesions
Appear as intranuclear, eosinophilic inclusions surrounded by a clear halo
Bordatella Pertusis - Culture requirements
Bordet-Gengou (potato) agar
Bacterial meningitis - Most common organisms in young adults (2)
Strep pneumo
N. meningiditis
Red pigment observed in UTI culture - what’s the pathogen?
Serratia - gram negative bacillus commonly causing nosocomial UTI
Clue Cells
Vaginal epithelial cells coated in bacteria (Gardenella vaginalis)
Classic microscopic finding of bacterial vaginosis
Bacterial pneumonia occurring secondary to influenza - most common pathogens? (3)
Streptococcus pneumoniae
Staphylococcus aureus
H. influenzae
Neonatal conjunctivitis - how to differentiate 2 common causes?
Presents as inflammation, swelling around the eyelids, and purulent yellow discharge
Chlamydia trachomatis - sx begin 5-14 days after birth
Neisseria gonorrhoeae - sx present 2-5 days after birth
CMV Retinitis
Presents with rapidly diminishing sight - loss of central vision with floaters and blind spots
Fundoscopic exam demonstratates necrotizing retinitis, perivascular hemorrhages, and retinal detachment
Maculopapular rash on the palms & soles - Associated diseases
Secondary syphilis
Cocksackie A virus
Rocky Mountain Spotted Fever
Which bacterial exotoxins work by ADP-ribosylation of EF-2?
Diptheria
Pseudomonas
What is the mechanism of Shiga toxin, and in which diseases is it seen?
Shiga toxin inactivates ribosomes, leading to inhibition of protein synthesis and cell death
Causes hemolytic uremic syndrome including renal failure, microangiopathic hemolytic anemia, DIC, thrombocytopenia
Seen in Shigella infection and Enterohemorrhagic E. coli (EHEC)
“Slapped cheeks”
AKA erythema infectiosum - blanchable erythema on the cheeks with perioral pallor
Seen in “Fifth Disease” caused by Parvovirus B19; rash appears after fever has resolved
“Strawberry tongue”
Scarlet fever
Kawasaki Disease
Toxic Shock Syndrome
Flavivirus
Enveloped, positive sense, single-stranded RNA virus
HCV Yellow Fever Dengue St. Louis encephalitis West Nile Virus
Part of the Arbovirus classification (except HCV)
Filoviruses
Enveloped, negative-sense, single stranded RNA Virus
Ebola
Marburg
Paramyxoviruses
Enveloped, negative-sense, single stranded RNA Viruses
Parainfluenza
RSV
Measles
Mumps
Rhabdoviruses
Enveloped, single stranded, negative sense RNA virus
Rabies
Picornaviruses
Non-enveloped, single-stranded, positive-sense RNA virus
Rhinovirus
Poliovirus
Coronaviruses
Enveloped, single-stranded, positive-sense RNA Viruses
SARS
MERS
Orthomyxoviruses
Enveloped, negative-sense, single stranded RNA virus genome in 8 segments
Influenza
Bunyavirus
Enveloped, negative-sense, single-stranded RNA virus
California encephalitis
Hantavirus
Romana Sign
Unilateral periorbital swelling
Characteristic of the acute phase of Chagas Disease
Urease positive organisms
Staphylococcus Ureaplasma Proteus Klebsiella Pseudomonas
Is candida germ tube positive or germ tube negative?
Germ tube positive
Special stain for identification of Bartonella henslae
Warthrin-Starry stain shows gram-negative proteobacterium
