STEP1_Microbiology Flashcards
Streptococcus pneumoniae differs from other bacteria in that it produces α-hemolysis, resulting in __________ in blood agar.
green halos
What bug produces IgA protease enzymes that cleave secretory IgA antibodies?
S. pneumoniae
List the bacteria that secrete IgA proteases?
- Neisseria meningitidis,
- N. gonorrhoeae
- H. influenzae
- Strep. pneumoniae
What virus has the following characteristics?
localized infections consistening of non-erythematous, pearly, dome-shaped papules on skin. Mainly in peds and immunocompromised Pt. Self-limiting.
Poxvirus; which causes Molluscum contagiosum
What are the two most common causes of bacterial meningitidis in young adults?
S. Pneumoniae & N. meningitidis
_____________________ is an aerobic, gram-Positive, oxidase-Positive bacteria the produces pyocyanin –> making look blue-green in color.
Pseudomonas aeruginosa
What is the MOA of the main virulence factor of Pseudomonas?
Endotoxin A;
ADP ribosylates and inhibits elongation factor 2 in host cells –> inhibiting protein synthesis.
(this is similar to Diphtheria toxin)
A medium made of charcoal yest extract with increased levels of iron and cysteine are best used to culture what bacteria?
Legionella pneumonphila
Chocolate agar with factor V and X is used to culture what bacteria?
H. influenzae
What medium is needed to best culture Corynebacterium diphtheriae?
Loffler’s medium
Thayer-Martin medium is used to culture what bacteria?
Neisseria gonorrhoeae
What bacteria shows up as black colonies on cystine-tellurite agar?
Corynebacterium diphtheriae.
Uses exotoxins that inhibits protein synthesis via ADP-ribosylation of EF-2
Is S. agalactiae bacitracin resistant?!
YES!
the other bugs that are Group A are not!
What is the most common cause of neonatal meningitis?
Group S Strep (GBS).
S. agalactiae is beta-hemolytic, gram-positive coccus found in chains.
Clostridium tetani is a spore-forming, gram-positive bacillus that is transmitted through contaminated soil/feces, whose entrance into the body is often facilitated by puncture wounds from sharp objects like nails. It produces an exotoxin that blocks ____1____ and ____2____ from inhibiting muscular contractions, resulting in tonic contraction (tetanus).
- glycine
2. GABA
____________ infection, which presents with a painless ulcer with a beefy red base and irregular borders
Klebsiella granulomatis
The chancre from T. pallidum infection is noted to having what features?
painless, non-exudative, clean, hard base with indurated margins (“punched out base with rolled edges”)
What bugs causes an infection, described as a deep, undermined, painful purulent ulcer with soft ragged edges.
Hemophilus ducreyi
_____________ is mainly found in tropical areas and causes yaws, which manifest as destructive lesions of skin and bones.
Treponema pertenue
How do gumma present on the skin?
Ulcers or granulomatous lesions with round, irregular shape.
Treponema pallidum is a ____1____ spirochete that causes ____2____.
- microaerophilic
What are the defining characteristics of each stage of syphilis?
1st stage: painless chancre
2nd stage: painless rash on the palms of the hands and soles of the feet.
3rd stage: neurosyphilis (demyelination of the posterior column), gumma formation, and aortitis. The aortitis can result in an aortic aneurysm.
Haemophilus ducreyi is a small, pleomorphic, gram-____1____ that causes ____2____, an ulcerative genital lesion.
- negative bacilli
2. chancroid
What pathogen grows in short parallel chains, sometimes referred to as “school of fish” in appearance under microscopy.
H. ducreyi
What pathogen is the causative agent of granuloma inguinale (donovanosis), an ulcerative genital lesion.
Klebsiella granulomatis;
Gram-negative, rod-shaped bacterium
Acyclovir, famciclovir, and valacyclovir are _______ analogs used to treat active HSV and VZV (not latent forms).
guanosine
__________ is also a guanosine analogue but has limited efficacy against CMV
Acyclovir
Acyclovir, famciclovir, and valacyclovir are _________ analogs.
guanosine
A gumma is a soft, non-cancerous granuloma that typifies tertiary syphilis. Histological features include what?
a central region of coagulative necrosis, palisading macrophages, multinucleated giant cells, fibroblasts, lymphocytes, and plasma cells. The causative organism, Treponema pallidum, is only rarely found.
What bacteria are poorly Gram stain and can be remembered by the mnemonic “These Microbes May Lack Real Color”?
- Treponema
- Mycobacteria
- Mycoplasma
- Legionella pneumophila
- Rickettsia
- Chlamydia
Why does Treponema poorly gram stain?
Treponema are too thin to be visualized and can be visualized by dark-field microscopy and fluorescent antibody staining.
Why Mycobacteria does poorly gram stain?
Mycobacteria have a high lipid content and mycolic acids in cell wall can be detected by carbolfuchsin in acid fast stain.
Why does Mycoplasma poorly gram stain?
Mycoplasma has no cell wall.
Why does Legionella poorly gram stain?
Legionella pneumophila are primarily intracellular and can be visualized via silver stain.
Why does Rickettsia poorly gram stain?
Rickettsia are intracellular parasites.
Why does Chlamydia poorly gram stain?
Chlamydia are intracellular parasites that lack classic peptidoglycan because of low muramic acid.
Aztreonam is synergistic with what other antibiotic?
Aminoglycosides
Staphylococcus epidermidis/saprophyticus are coagulase-____________
negative
Aminopenicillins are positively-charged R-groups, extended spectrum ABX. What bugs do they Tx? (8)
- H. flu
- F. Pylori
- E. coli
- Listeria
- Proteus
- Salmoanella
- Shigella
- Enterococci
Which strep is optochin sensitive? or resistant?
S. pneumoniae is optochin sensitive.
S. viridens is optochin resistent
________ is an aminoglycoside that can be applied topically. the other aminoglycosides are parenteral (IV)
Neomycin
Despite their “-mycin” suffix, what antibiotics are not aminoglycosides?
- Macrolides such as erythromycin, clarithromycin, and azithromycin
- Lincosamides such as clindamycin and lincomycin
- Streptogramins such as pristinamycin
- Vancomycin
- Daptomycin
What type of vaccine is the vaccine for Smallpox?
Live attenuated
What type of vaccine is the vaccine for Yellow fever?
Live attenuated
What type of vaccine is the vaccine for Rotavirus?
Live attenuated
What type of vaccine is the vaccine for chickenpox (VZV)?
Live attenuated
What type of vaccine is the vaccine for Sabin polio virus?
Live attenuated
What type of vaccine is the vaccine for MMR?
Live attenuated
What type of vaccine is the vaccine for Influenza (intranasal)?
Live attenuated
What type of vaccine is the H. influenzae type B vaccine?
conjugated vaccines for encapsulated bacteria
What type of vaccine is the Meningococcal vaccine?
conjugated vaccines for encapsulated bacteria
What type of vaccine is the Prevner vaccine?
conjugated vaccines for encapsulated bacteria
Pneumococcal PCV
Name two examples of subunit vaccines?
Subunit vaccines include Hepatitis B (HBsAg of HBV)
-and-
Human Papillomavirus (Gardasil covers HPV types 6, 11, 16, and 18). c
What type of vaccine is the Rabies vaccine?
Killed vaccines
What type of vaccine is the Influenza vaccine?
Killed vaccines
What type of vaccine is the Salk vaccine?
Killed vaccines
What type of vaccine is the Hepatitis A (HAV) vaccine?
Killed vaccines
_______________ syndrome is cuased by C. trachomatis. What is the triad of Sx that make up this syndrome?
Reactive Arthritis (Reiter’s Syndrome)
- arthritis
- urethritis
- conjuctivitis
Which Hepatitis B antigen is the best marker of viral activity?
HepB “e” antigen, which is produced during viral replication in the bloodstream. (Also indicates low transmissibility.)
Real-time PCR for HBV DNA can also be used to assess viral activity.
Which serologic marker indicated immunity to future hepatitis B infections?
Anti-HBs
Anti-HBs is an antibody to HBsAg and indicated immunity and marker of cleared infection to HBV.
The chancre from _______ infection is noted to having a painless, non-exudative, clean, hard base with indurated margins (“punched out base with rolled edges”).
The chancroid from what bug is PAINFUL?
T. pallidum
Hemophilus ducreyi infection, described as a deep, undermined, painful purulent ulcer with soft ragged edges.
What is the CV manifestation of tertiary syphillis?
affects ascending thoracic aorta. –> Dilated Aorta and Aortic Valve Regurg.
What is the morphology of Treponema pallidum and what disease does it cause?
microaerophilic spirochete –>
syphilis
What does Anti-HBc indicate in serology?
Anti-HBc is antibody to HBcAg. IgG Anti-HBc indicates a prior exposure to the virus.
What is the serology of a Pt. with an ACUTE infection of Hep B?
HbsAg ---> ? anti-HBs ---> ? anti-HBc IgM or IgG ??HBeAg ---> ? anti-HBe ---> ? HBV DNA ---> ?
HbsAg+, anti-HBs-, anti-HBc IgM, HBeAg+, anti-HBe-, HBV DNA+ is a pattern seen in acute infection.
Which bacterial exotoxins functions as proteases? (5)
- C. botulinum toxin
- C. tetanus toxin
- B. anthracis LF toxin
- Staph aureus exfoliatin
- Strep pyogenes exotoxin B (SpeB)
Which bacterial exotoxins increase cAMP? (6)
ADP-ribosylation –> activated G_s –> incrases cAMP –> watery diarrhea
- Pertussis toxin
- Edema EF (B. anthracis)
- Cholera toxin
- Heat Labile (LT) toxin of ETEC
- B. Cereus enterotoxin
- Campy jejuni enterotoxin
What does superantigen work?```
Superantigens function by cross-linking the α chain of MHC-II on the antigen-presenting cell with the variable region of the β-chain (Vβ) of T cell receptors on CD4+ Th cells. This creates polyclonal T-cell activation, leading to increased IL-2 and IFN-γ. The resulting release activates macrophages and promotes the release of proinflammatory cytokines such as IL-1, IL-6, TNF-α.
Which bacterial exotoxin increase cGMP? (thereby increase secretions)
- ST (heat-stable toxin of ETEC)
- Enterotoxin of Yersinia enterocolitica
What two bacterial exotoxins use ADP-ribosylation to inactive EF-2 –> inhibition of protein synthesis?
- Diphtheria toxin and exotoxin A of Pseudomonas spp.
What are the exotoxins which form pores in cell membranes? (4)
- Clostridium perfringens enterotoxin
- Bacillus anthracis protective antigen (PA) factor
- Staphylococcus aureus alpha-toxin
- Streptococcus pyogenes streptolysin O
Pertussis toxin works by _____________ that inactivates Gi, increasing cAMP and secretions that lead to edema.
ADP-ribosylation
Pertussis toxin works by ADP-ribosylation that results in what?
inactivates Gi, increasing cAMP and secretions that lead to edema.
Exotoxins which inhibit protein synthesis include (4)
- Diphtheria toxin
- Exotoxin A of Pseudomonas spp.
- Verotoxin (Shiga-like toxin) of EHEC
- Shiga toxin of Shigella spp.
Drug induced-hemolytic anemia is classically associated with what drugs? (Although can happen with any drugs)
- PCNs
- Cephalosporins
- Quinidine
- Levodopa/methyldopa.
infects small intestine; flagellated, crescent-shaped protozoan organism has a characteristic “facelike” appearance.
==???
Giardia lamblia is the most prevalent protozoan infection in the human small intestine.
intracellular protozoan, causes diarrhea, visuallized as red or pink stained oocystuding modififed acid-fast stain.
== ??
cryptosporidum parvum
usually infects the large intestine and/or liver; produces inverted flask-shaped lesions in large intestine with extension to peritoneum and liver, lungs, brain, and heart.
Entamoeba histolytica
what Amoebae causes PAM if the pt. is swimming in warm, freshwater lakes; and how does it enter the body?
Primary amebic meningoencephalitis: Naegleria fowleri.
Acquired from diving into warm, freshwater lakes;
Amoebae enter the brain through cribriform plate during forceful diving.
Treatment: amphotericin B (rarely successful)
________ is a gram-positive, anaerobic rod that is associated with gangrene and a mild form of food poisoning via an enterotoxin.
C. perfringens
_____________ is a gram-negative, lactose-negative rod associated with bloody diarrhea but not with gastric ulcers.
Shigella dysenteriae
There is an important association between colon cancer and endocarditis due to _____________.
Streptococcus bovis
S. bovis is a group D Streptococcus whose cell wall has glycerol teichoic acid.
The triad of arthritis, urethritis, and conjunctivitis == ???
Reiter syndrome (reactive arthritis):
~w. HLA-B27
Previous infection wath what bugs can lead to Reiter syndrome (reactive arthritis)?
- Shigella
- Salmonella
- Yersina
- Campylobacter
- Chlamydia
Hematogenous spread of N. gonorrhoeae infection –> ???
Septic Arthritis
Gram-Neg, oxidase-neg bacillus = ???
Klebsiella pneumoniae;
~w/ alcoholism, lobar consolidation, and “currant jelly” sputum.
A gram-negative, oxidase-positive bacillus describes ???
Pseudomonas aeruginosa
Gram-Positive, catalase-neg, coccus descirbes what genus?
Strepococcus
What is the immunodiffusion test used to identify toxin-producing strains of Corynebacterium diphtheriae.
ELEK test
What test would be used to identify Neisseria, Pseudomonas, and Vibrio and distinguish them from members of the family Enterobacteriaceae?
Oxidase test
What virus is a member of the Hepevirus family and whose infection of pregos has a high mortality rate?
Hepatitis E virus belongs to the Hepevirus family, which has naked, single-stranded, positive-sense RNA.
Which hepatitis virus is part of the Flaviviridae family
HepC
What is the family to which hepatitis B virus belongs?
Hepadnaviridae
It is an enveloped double-stranded DNA virus that is sexually or parenterally transmitted.
What is the family to which hepatitis A virus belongs?
Picornaviridae
naked capsid RNA viruses to which hepatitis A virus belongs
Immunocuppressed pt. with fungal meningitis, think?
Crytococcus neofromans.
encapsulated yeast acquired from pigeon droppings and urease-positive.
encapsulated yeast acquired from pigeon droppings and urease-positive.
dX via laxtex particle agglutination of CSF
Crytococcus neofromans.
Intracellular yeast within Macrophages are the diagnostic form of _______________ , which, despite its name, is not an encapsulated yeast. It is primarily a pulmonary infection acquired by exposure to the droppings of birds or bats.
Histoplasma capsulatum
what would be the yeast forms characteristic of Coccidioides immitis, which may be a cause of fungal meningitis in immunologically compromised individuals but is geographically restricted to the Sonoran desert zone of the United States (San Joaquin Valley fever).
Spherules
what organism causes regional lymphadenopathy, +/- low-grade fever and headaches?
Bartonella henselae; “cat-scratch fever”
in the immunocompromised, can cause bacillary andiomatosis.
tx. with Azithromycin or doxycyline
What is marked by mild nonspecific symptoms or pneumonia, and may progress to myocarditis or hepatitis?
Q fever!
Coxiella burnetii
