Bacteria Flashcards
Pt. comes in with diffuse body rash, pharyngitis, and intense reddening & swelling of the tongue. Lab analysis shows G+ organism. What is this disease and what toxin is it caused by?
- Scarlet Fever – Caused by Strep. pyogenes
2. SPE (Streptococcal pyrogenic exotoxin)
Patient presents with polyarthritis, heart valve stenosis and murmurs, nodules on the forearms, a rash with thick red borders, & rapid involuntary movements of hands. Organism is catalase negative. What disease is this and what virulence factor causes it. Also, what serological test should be ran to determine this infection?
- Rheumatic Fever – caused by Strep. pyogenes
- M protein
- ASO titer (anti-Streptolysin O)
Pt presents with gross hematuria, appearing dark brown. He had a honey-crusted skin infection 2 weeks prior. Labs show cocci in chains. What disease is this, what type of reaction is causing it, and what is the organism?
- PSGN (Post-streptococcal Glomerulonephritis)
- -Secondary to Impetigo (honey-crusted skin infection) - Type III Hypersensitivity reaction
- Strep. pyogenes
2 month of Pt presents with nuccal rigidity and neurologic symptoms. Lab tests show the organism has a positive hippurate test and CAMP test. Blood agar shows complete (beta) hemolysis. What is the infant infected with and what is the disease?
- Strep. agalactiae
2. Meningitis
Pt presents with rust-colored sputum and lobar infiltrate shown on x-ray. What are the diagnostic features of this microbe?
Strep pneumoniae
- -Bile solube
- -Optochin-sensitive
- -Lancet-shaped
- -G+ diplocci
Pt presents with endocarditis. Recent history shows he had dental work done. Organism is resistant to optochin and can colonize on bile (bile-insoluble). What organism is causing this patient’s symptoms?
Strep Veridans group (Strep. mutans or Strep. sanguinis)
What microbe is associated with sheep’s wool and hemorrhagic mediastinitis? Another symptom can be a black cutaneous necrotic lesion with surrounding erythematous ring (black eschar). What toxins/mechanisms, virulence factors, and lab features are involved with this organism?
Bacillus anthracis
- -Lethal Factor (cleaves MAP kinase & causes tissue necrosis)
- -Edema Factor (acts as adenylate cyclase to increase cAMP & move fluid to extracellular space – causing edema)
Virulence factor: poly-D glutamate PROTEIN capsule
Lab feature: G+ rod in chains; obligate aerobe
Name all of the G+ bacilli
- Bacillus anthracis & Bacillus cereus
- All Clostridium (tetani, botulinum, difficile, & perfringens)
- Corynebacterium diphtheriae
- Listeria monocytogenes
Child presents with spastic paralysis. Recent history shows that the child was playing near a construction zone and had scraped up his feet and legs. Physical exam shows the start of Risus sardonicus and opisthotnos. What organism has infected the child and what is it’s mechanism?
Clostridium tetani
- Risus sardonicus = “evil smile/grin” due to lock jaw
- Opisthotonos = arching of the back due to powerful spastic contraction of back extensor muscles
Mechanism: Tetanus toxin cleaves SNARE complex within Renshaw cells (which contain inhibitory NT’s like Gly and GABA)
A patient presents with increasing flaccid paralysis that started up towards his neck and has progressed down his body. He says members of his family also have similar symptoms, including his baby sister who cannot eat solid foods. What pathogen has infected the patient, what was the specific modes of transmission, and what is the mechanism?
Clostridium botulinum – caused by eating home-canned foods and/or improperly pasteurized canned foods.
**The baby sister was likely infected by consuming honey, which commonly has C. botulinum spores in it.
Mechanism: cleaves SNARE complex of excitatory motor neurons containing Ach
What organism is associated with nosocomial infection causing watery diarrhea and often precedes taking antibiotics like Clindamycin?
Clostridium difficile
What organism is associated with deep penetrating wounds and/or motorcycle accidents that contains an alpha-toxin (double zone of hemolysis on blood agar). This should cause soft tissue necrosis
Clostridium perfringens
What organism is strongly associated with colon cancer and causes SBE (subacute bacterial endocarditis)
Strep. bovis
60 year old patient presents with fever, muscle aches, diarrhea and gastroenteritis. You also note some neurological involvement and suspect meningitis. Lab tests show a G+ rod shaped organism that is catalase positive and motile, moving around by actin rockets. Recent history shows patient was eating a lot of Italian food, especially caprisi salad. What organism is the cause of these symptoms?
Listeria monocytogenes
What organisms are known for infecting patients with Complement deficiencies? Labs showing G– diplococci is characteristic of what? How do you further lab test to differentiate this genus?
Neisseria genus
Maltose fermentation test - only N. meningitidis is +
N. meningitidis is known for causing ______ in what population of people? This is due to the capsule component ______ that blebbs off and causes systemic problems.
- Meningitis in populations living in close-quarters (esp. dorms)
- LOS proteins (lipooligosaccharides)
What organisms can ferment lactose? How does this present on a lab test?
- The Enterobacteriacae family (Enterobacter cloacae, Serratia marcescens, Klebsiella pneumoniae)
- E. coli
This shows pink colonies when grown on MacConkey agar
Pt presents with pulmonary symptoms. X ray shows atypical pneumonia and lab results show a non-motile G– rod that is urease positive. Pt. has thick gelatinous sputum. What organism is this and in what setting does infection typically occur?
- Klebsiella pneumoniae
2. In hospitals (enterobacteriaceae are all nosocomial infections)
40 year old African American patient presents with red spots on the abdomen, complains of constipation, and has pea-soup diarrhea. Lab culture shows a flagellated G– rod that grows black colonies on Hektoen agar. Pt also complains of pain in his bones, and PHM shows patient has sickle cell disease. What organism has infected this patient?
Salmonella typhi
A person eats under-cooked chicken and has bloody diarrhea. What virulence factor is associated with this bug?
Salmonella enteritidis – Type III secretion system
Person presents with dysentery (blood diarrhea), lab results show an immotile G– rod organism that grows green on Hektoen agar. What organism is this and how does its toxin work? What can this cause in children?
Shigella dysenteriae
- -Shiga toxin binds 60s subunit of ribosomes & inhibits translation –> causes cell injury/death
- -Causes platelet aggregation in blood & causes lysis of nearby RBC’s into schistocytes
Causes HUS (Hemolytic uremic syndrome in children) --Sudden acute renal failure following prodromal diarrhea
12 year old Pt presents with GI symptoms and dysentery after eating at a hamburger stand. Lab results show motile G– rod that is catalase positive, grows pink colonies on MacConkey agar, and grows metallic green colonies on EMB (Eosin-Methylene blue) agar. What organism is this? What important serotype and toxin cause these symptoms?
This is EHEC (Enterohemorrhagic E. Coli)
-Impt serotype: O157:H7
Shiga-like toxin: same mechanism as Shiga toxin (binds 60s unit of ribosomes)
Patient returning from a trip to Mexico has had watery diarrhea for the last two weeks. What organism is causing this and what toxins are causing the symptoms?
ETEC (Enterotoxigenic E. coli) –> Traveler’s Diarrhea
- Heat-labile toxin (increases cAMP)
- Heat-stable toxin (cGMP)
Patient presents with bloody diarrhea, RLQ pain, and fever. History is unremarkable than having two dogs and eating a normal diet. Patient drinks a lot of milk products to keep her bones healthy. Lab results show G– rod with bipolar staining and no other remarkable tests. What is causing these symptoms?
Yersinia enterocolitica
–Can mimic appendicitis
A yard worker presents with swollen, tender lymph nodes in the groin, armpit, and neck. There appears to be organ abscesses on US and slight necrosis of extremities. What pathogen is causing this and what are the important virulence factors?
Yersinia pestis (the swollen LN’s are called buboes)
Virulence factors:
- Yops (Yersinia outer proteins) that cause macrophage and neutrophil dysfunction
- Type III secretion system
Patient presents with copious amounts of bloody diarrhea, as well as symptoms of arthritis and slight muscle paralysis that started in the lower extremities, moving upward. These that started shortly after the diarrhea. Lab results show a motile curved G– rod that is oxidase positive. What is the infectious agent?
Campylobacter jejuni
Ascending paralysis is called Guillain-Barre Syndrome
These bacteria are comma shaped and known for infecting oysters
Vibrio parahaemolyticus & Vibrio vulnificus
Patient presents with profuse watery diarrhea containing flecks of mucus material. Lab results show a curved, comma shaped G– rod that is oxidase positive and grows on alkaline media. What organism is causing these symptoms and through what mechanism?
Vibrio cholerae
Cholera toxin: constitutively activates Adenyly cyclase and increases cAMP, causing water to move into intestinal lumen
This pathogen is associated with nearly all duodenal ulcers. Name it and the most important virulence factor for survival and colonization.
Helicobacter pylori
-Urease positive - very important since it colonizes the stomach
This organism causes hot tub folliculitis, is the #1 cause of nosocomial pneumonias and UTI’s. Can cause osteomyelitis in IV drug users & diabetics, as well as Otitis externa. It is oxidase and catalase positive, obligate aerobe, G– rod, and is associated with burn victims & a grape-like odor.. What is the organism and its toxin/mechanism?
Pseudomonas
Exotoxin A: ribosylates EF-2 and inactivates it, which inhibits protein synthesis and causes cell death
Male patient presents with flank pain and burning on urination. Urine sample shows kidney calculi with a staghorn shape, containing struvite. The urine has a slight fishy odor, and labs show a G– rod with swarming motility. What organism is present?
Proteus mirabilis
A 2 year old is brought in by his mother. He has a vigorous cough that causes exaggerated, intense sound upon inhalation. What organism causes this presentation, what is its primary virulence factor, and what is its toxin(s)/mechanism?
Bordetella pertussis - causes Whooping cough
Virulence factor: Filamentous hemagglutinin (its Pili)
Toxins:
-Pertussis toxin: ribosylates Gi & causes rise in cAMP –> disables chemokine rec/migration for lymphocytes
-Tracheal toxin: damages ciliated cells in respiratory epithelium
Patient presents with extremely inflamed epiglottis, drooling, and slight inspiratory stridor. Lab results show a G– organism with coccobacillary shape that can only grow on Chocolate agar due to the need for Factor V (NAD) & Factor X (hematin). You tell the patient that they are infected with ________ and are lucky it isn’t a strain that has ______, which allows it to cause meningitis.
- Haemophilus influenzae
2. Type B capsule
A patient presents with unilobar infiltrate (atypical pneumonia), hyponatremia, diarrhea, and a headache with slight confusion. Lab results show organism that poorly gram stains, must be visualized with a Silver stain, and only grows on Charcoal Yest Extract agar due to the presence of ___ and ___. What organism causes these symptoms, and what do you call the disease?
- presence of Cysteine and Fe
- Legionella: –> causes Legionnaire’s Disease (symptoms seen in question)
Also causes Pontiac Fever: Pt has fever and malaise w/ diagnostic lab features
Bartonella henselae is caused by what and it causes what two diseases? What stain must be used to visualize it?
- Caused by cat scratches
- Causes cat-scratch fever (fever + axillary lymphadenitis)
- Causes Bacillary angiomatosis (only in immunocompromised): fevers, chills, headache, & red raised vascular lesions all over skin
- Warthin-Starry stain (type of silver stain)
A farmer presents with enlargement of spleen, liver, and LN’s. He has an undulating fever, chills, and anorexia. What is causing his symptoms?
Brucella
A patient presents with an isolated ulcerated site on forearm. She claims to have been bitten by a dermacentor tick. Physical exam shows regional lymphadenopathy. Lab results show a G– coccobacillary shape. What organism most likely infected this patient?
Francisella tularensis
Patient presents with a cat bite on his arm and shows rapidly progressing cellulitis with abscess formation. Lab results show an encapsulated G– rod with bipolar staining that is catalase positive, oxidase positive, and grows especially well on 5% sheep’s blood agar.
Pasteurella multocida
Patient presents with well-demarcated, hairless, hypoesthetic skin plaques. What pathogen and disease is present here?
Mycobacterium leprae
Causes Leprosy (aka: Hansen's Disease) --This is Tuberculoid / Th1 response
Patient presents with “glove and stocking” neuropathy, thickening of skin, loss of eyebrows, collapse of the nose, and has numerous poorly demarcated raised lesions on surfaces of extremities. What pathogen and disease is present here?
Mycobacterium leprae
Causes Leprosy (aka: Hansen’s Disease)
- -This is Lepromatous / Th2 response
- -Lion facies = Leprosy
Patient presents with a tick bite, which you identify as an Ixodes tick. Organism stains under light microcope with a Wright’s stain and a Giemsa stain. You suspect Lyme disease since Pt lives in Northeastern US. What symptoms would you suspect?
- Bull’s eye rash (erythema chronicum migrans) + fever/chills
- Heart block caused by myocarditis w/ possible Bell’s palsy
- Migratory polyarthritis
A surfer presents with flu-like symptoms and conjunctival suffusion (red eye but no inflammatory exudate). Lab shows a “question mark” shaped organism. What organism is this and what long-term complication should you be worried about if this goes untreated?
- Leptospira interrogans –> causes Weil’s Disease (Leptospirosis)
- Renal dysfxn & liver damage/jaundice
What should you be aware of when starting treatment for a case of syphilis.
Jarish-Herxheimer reaction:
-Begins withing hours of treatment & causes fever, chills, & headache due to spirochetes dying and releasing toxins into blood
What are the buzzwords for congenital syphilis?
- Saber shins (anterior bowing of tibia)
- Saddle shaped nose
- Hutchinson’s teeth (notched incisors) & Mullberry molars)
- Deafness
What are all of the obligate intracellular bacteria?
Chlamydia, Coxiella burnetii, & both Rickettsia
What three pathologies does Chlamydia trachomatis cause?
- Trachoma: leading cause of blindness worldwide
- STI
- LGV (lymphogranuloma venerum): also STI but starts with genital ulcer that causes tender lymphadenopathy months later
What does Chlamydophila psittaci cause?
An atypical pneumonia that is transmitted specifically through bird droppings
A farmer presents with pneumonia-like symptoms, fever, headache, and also hepatitis. Lab shows a G– rod that must be grown intracellularly in tissue sample. What organism is causing these symptoms and what disease is it?
- Coxiella burnetii –> causes Q Fever
Woman presents with complaint of vaginal discharge having a fishy odor. Lab shows a gram variable rod and positive KOH Whiff test. Wet mount shows “clue cells”. What organism is causing these symptoms?
Gardnerella vaginalis - causes bacterial vaginosis
Military recruit presents with cough and respiratory symptoms. X ray shows patchy infiltrate. Lab shows an organism with no stainable cell wall that contains cholesterol and requires Eaton’s agar to grow. Blood test shows cold agglutinins (RBC clumping at cold temps due to IgM complexing). What do you suspect?
Infection with Mycoplasma pneumoniae
What organisms show a positive Weil-Felix agglutination test? (This shows OX19-OX2 markers)
Rickettsia species
A prisoner of war suddenly developed a rash on his trunk that spread outwards towards his extremities, although it spared his hands, feet, & face. He has myalgias, arthralgias, pneumonia symptoms, and encephalitis. What bug does he have and how is it spread?
- Ricketssia prowazekii –> causes Thyphus
2. spread by lice
Hiker in NC was bit by a dermacentor tick. Two weeks later he developed a rash on his extremities that spread centrally. He has fever, headache, and myalgias. What is the diagnosis?
- Rickettsia rickettsii infection –> causes Rocky Mountain Spotted Fever
Patient presents with pneumonia showing abscess formation, brain abnormalities showing abscess formation, and cutaneous lesions with inflammation. Labs show obligate aerobe, G+ branching filamentous rod. What is the infection caused by?
Nocardia
Patient presents with sinus tracts that have a yellow discharge containing sulfur granules. It started after he got dental work done, followed by a non-tender lump on his jaw. Labs show an obligate anaerobe, G+ branching filamentous rod. What is the diagnosis?
Actinomyces israelii –> causes Cervicofacial actinomycosis
