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331 Cards in this Set

  • Front
  • Back
What is positive sense RNA?
Viral RNA that can be used as mRNA
What is negative sense RNA?
Viral RNA that is complientary to mRNA and needs virion associated RNA-dependant RNA polymerase
What are the arboviruses?
Togavirus, flavivirus, bunyavirus
Viruses inactivated by heat, detergents and solvents
Enveloped viruses
Viruses that can't be inactivated by heat, detergents and solvents
Naked viruses
How do dsDNA viruses make mRNA?
Negative strand of genome serves a template for mRNA. No intermediate.
How do retroviruses make mRNA?
mRNA is transcribed from dsDNA intermediate.
How do +RNA viruses make mRNA?
Through a -RNA intermediate
How do -RNA viruses make mRNA?
RNA is template for +mRNA without intermediate
What are the killed vaccines?
Rabies, Influenza, Polio (Salk), A hepatitis. "RIP Always"
What are the live vaccines?
Mumps, Rubella, Varicella-Zoster, Measles, Adenovirus, Polio (Sabin), Small Pox, Yellow Fever. "Mr. V.Z. Mapsy"
What are the DNA virus families?
Herpes, Hepadna, Adeno, Parvo, Pox, Papova. "HHAPPPy"
What are the naked virus families?
Calicivirus, PEeCoRnA virus, Reovirus, Parvo, Adeno, Papilloma, Polyoma. "Naked CPR and PAPP smear"
What are the +RNA virus families?
Calici, PEeCoRnA, Flavi, Toga, Corona, Retro. "Call Pico and Flava To Come Rap"
What are the -RNA virus families?
PaRaMyxo, Rhabdo, Arena, Filo, Orthomyxo, Bunya, Delta. "Para Rabiar in the Arena, Fill or Buny"
Characteristics of DNA viruses
All dsDNA (except parvo); All linear (except papova, hepadna); Icosahedral (except pox); Replicate in the nucleus (except pox); All naked (except herpes, hepadna, pox)
Characteristics of Herpesviruses
Enveloped, dsDNA, linear, icosahedral, replicates in nucleus, intranuclear inclusion bodies and latency
Characteristics of hepadnaviruses
Enveloped, dsDNA, circular, icosahedral, replicates in nucleus
Characteristics of adenovirus
Naked, dsDNA, linear, icosahedral, replicates in nucleus
Characteristics of Parvovirus
Naked, ssDNA, linear, icosahedral, replicates in nucleus
Characteristics of Papovavirus
Naked, dsDNA, circular, icosahedral, replicates in nucleus
Characteristics of Poxvirus
Enveloped, dsDNA, linear, complex, replicates in cytoplasm (DNA-dependant RNA polymerase)
Characteristics of Caliciviruses
Non-enveloped, +ssRNA, linear, icosahedral
Characteristics of PEeCoRnA viruses
Non-enveloped, +ssRNA, linear, icosahedral
What are the Herpes viruses?
What are the PEeCoRnA viruses?
Polio, Echo, Coxsackie, Rhino, Hep A. "PEeCoRnAvirus"
What are the Caliciviruses?
HEV, Norwalk
What are the Reoviruses?
Reovirus, Rotavirus
What are the Flaviviruses?
HCV, yellow fever, dengue, St. Louis encephalitis, West Nile virus
What are the Togaviruses?
Rubella, eastern equine encephalitis, western equine encephalitis
What are the Retroviruses?
What are the Orthomyxoviruses?
What are the Paramyxoviruses?
Parainfluenza, RSV, Rubeola (Measles), Mumps. "PaRaMyxovirus"
What are the Rhabdoviruses?
What are the Filoviruses?
Pathogenesis of Parvovirus B19
Infects immature erythroid progenitors resulting in lysis. May cause aplastic crisis in sickle-cell anemia.
Pathogenesis of HSV
Infects epithelial cells with formation of vesicles. Establishes latent infection in the ganglion. Reactivation with stress.
Pathogenesis of VZV
Respiratory tract --> local lymph node --> primary viremia --> spleen and liver --> secondary viremia --> skin rash --> latency in dorsal root ganglia --> reactivation due to stress causes vesicular lesions and severe nerve pain
Pathogenesis of EBV
Infects nasopharynx, salivary and lymphoid tissue --> latent infection in B cells via CD21 receptor --> production of atypical T lymphocytes with heterophile antibodies
Pathogenesis of CMV
Infects salivary epithelial cells and latency in mononuclear cells (Owl eye inclusions)
Pathogenesis of Polio virus
Destroys anterior horn motor neurons
Pathogenesis of Rabies virus
Binds peripheral nerves via nicotinic Ach receptor --> retrograde transport to dorsal root ganglia --> brain
Pathogenesis of Influenza virus
Hemaglutinin binds sialic acid on epithelium, hemagglutinates RBCs and induces antibodies. Neuroaminidase cleaves sialic acid with release of virus. Mutations of HA and NA cause genetic drift and epidemics. Genetic reassortment causes genetic shift and pandemics.
Diseases caused by Parvovirus B19
Erythema infectiosum (raised indurated "slapped cheek" facial rash). Hydrops fetalis and spontaneous abortions.
Diseases caused by HPV
Common warts (2, 4); Plantar warts (1); Condylomata acuminata; Benign genital warts (6, 11)(90%); Cervical intraepithelial neoplasia (16, 18). Find koilocytic cells in biopsy or PAP. DNA probes and PCR to determine strain.
Diseases caused by HSV-1 and HSV-2
Gingivostomatitis and cold sores (latent in trigeminal mucosa); Painful genital vesicles (latency in sacral ganglia); Keratoconjunctivitis; Meningoencephalitis (focal temporal lessions); Neonatal herpes (passage through birth canal, disseminated, liver and encephalitis involvement). Tzanck smear shows multinucleated giant cells.
VZV. Fever, pharyngitis, asynchronous rash.
VZV. Pain and vesicles restricted to one dermatome in the 5th or 6th decade. Reactivation of latent infection.
Heterophile+ mononucleosis
EBV. Generalized teder lymphadenopathy, splenomegaly with latency in B cells. Atypical lymphocytes and heterophile antibodies that agglutinate cow and sheep RBCs.
Malignancies by EBV
Burkitt's lymphoma: t(8:14) mandible or abdomen; Hodgkin lymphoma; Nasopharyngeal CA.
Heterophile- mononucleosis
CMV. Generalized tender lymphadenopathy, splenomegaly, Owl-eye inclusions
Cytomegalic inclusion disease
CMV. MC in-utero infection in US. Jaundice, hepatosplenomegaly, thrombocytic purpura, pneumonitis, CNS damage
CMV infections in immunocompromised
Interstitial pneumonitis, systemic infection in AIDS and transplant patients. CMV retinitis in AIDS patients.
HHV-6. Fever for 3-5 days followed by a non-pruritic maculopapular rash in the trunk.
Kaposi sarcoma
Malignancy of epithelial cells caused by HHV-8 which has a gene that turns on VEGF. Seen in AIDS.
Diseases caused by adenovirus
ARD and pneumonia in military recruits, college students associated to crowded quarters. Non-purulent pharyngoconjunctivitis (swimmers, sore throat coryza, red eyes) and keratoconjunctivitis (shipyard workers)
Diseases caused by Poxviruses
Variola (prodrome followed by synchronous rash and guarnieri intracytoplasmic inclussions); Molluscum contagiosum (umbilicated warts).
Diseases caused by Norwalk virus
Acute gastroenteritis. Watery diarrhea, nausea, vomiting. Associated to outbreak in cruise ships.
Destroys anterior horn motor neurons. Flaccid paralysis without sensory loss. Live vaccine (Sabin), killed vaccine (Salk)
Diseases caused by Coxsackie viruses
Aseptic meningitis, herpangina, myocarditis. Associated with type I DM and dilated cardiomyopathy.
MCC common cold
Rhinovirus, followed by coronavirus.
Infectious hepatitis
HAV. Fever, malaise, headache, vomiting, coluria, jaundice.
Culex mosquito
Aedes mosquito
Dengue, YFV
Fever, myalgia, arthralgia, petechiae, thrombocytopenia, neutropenia.
Yellow fever
Fever, jaundice, black vomit
Causes of encephalitis
Causes of asceptic meningitis
German measles
Rubella. Erythematous maculopapular rash from face to torso. No koplik spots.
SARS-CoV. Atypical pneumonia with dry cough, dyspnea, hypoxia, acute respiratory distress. Travel to Far East or Toronto.
AIDS gag gene
Encodes p24 capsid protein and p17 matrix protein
AIDS pol gene
Encodes reverse transcriptase (genetic drift of env gp), integrase (integrates DNA into genome), protease
AIDS env gene
Encodes gp160 which is cleaved to gp120 (binds CD4, CCR5, CXCR4) and gp41 (viral fusion)
AIDS tat gene
Upregulates transcription
Life cycle of AIDS virus
gp120 binds CD4/CCR5/CXCR4; endocytosis into cell looses envelope; dsDNA is synthesized by reverse transcriptase in cytoplasm; the DNA and integrase move into nucleous and incorporated into host genome forming provirus; transcription and translation; virus assembly and release taking host cell membrane and viral glycoproteins
Homozygous CCR5 mutation
Immune to HIV infection
Heterozygous CCR5 mutation
Slow course of AIDS
CXCR1 mutation
Rapid progression to AIDS
Symptomatic HIV infections
Bacillary angiomatosis, oral or vulvovaginal candidiasis, cervical dysplasia, hairy leukoplakia, ITP, listeriosis, PID, peripheral neuropathy
AIDS-defining conditions
Encephalopathy, recurrent pneumonia, fungal infections, esophageal or lung candidiasis, coccidioidomycosis, cryptococcosis, histoplasmosis, pneumoccystis jiroveci pneumonia, Kaposi sarcoma, Burkitt Lymphoma, CMV retinitis, cryptosporidiosis, isosporiasis, toxoplasmosis, mycobacterium TB or avium
AIDS infections with <400 CD4
Oral thrush, tinea pedis, shingles, TB, bacterial infections
AIDS infections with <200 CD4
Cryptosporidiosis, isosporidiosis, coccidiodomycosis, pneumocystis jiroveci
AIDS infections with <100 CD4
Candida esophagitis, toxoplasmosis, histoplasmosis
AIDS infections with <50 CD4
CMV retinitis and esophagitis, disseminated M. avium, cryptococcal meningoencephalitis
Cough, coryza, conjunctivits, photophobia, Koplik spots, maculopapular rash from face down. Complication: SSPE
Bilateral parotitis, fever, headache, swelling or parotids. Complications: pancreatitis, orchitis, infertility
Parainfluenza. Barking cough, inspiratory stridor, hoarseness.
MCC pneumonia in children 1m-18yr
Atypical pneumonia by RSV.
Hydrophobia, seizures, hallucinations, coma, death. Associated with bat or dog bites. Negri bodies.
Fever, chills, bronchiolitis, vomiting, croup, pneumonia. Can lead to Reye or Guillain-Barre.
MCC of infantile gastroenteritis
Viral genetics: phenotypic masking
Two virus infect a cell. The surface proteins of one virus (A) coat the genome of the other (B). The surface proteins of A determine infectivity while the viral progeny will have the genome of B.
Viral genetics: recombination
Exchange of genes between 2 chromosomes
Viral genetics: reassortment
Genetic shift. Two strains of a segmented virus coinfect a cell and recombine to produce a new progeny. Responsible for pandemics.
Viral genetics: complementation
One virus with a defective gene is complemented by another virus with working gene after they both coinfect a cell. Example: coinfection with HBV and HDV.
Characteristics of Malassezia furfur
Normal skin flora. Yeast clusters and short curved hyphae on KOH mount. "Spaghetti and meatballs" appearance.
Characteristics of dermatophytes
Filamentous monomorphic fungi. KOH mount shows arthroconidia and hyphae.
Types of dermatophytes
Microsporum, Trichophyton, Epidermophyton
Characteristics of Sporothrix schenckii
Hyphae with rosettes and sleeves of conidia in the envirenment. Cigar-shaped yeast in tissue
Characteristics of Histoplasma capsulatum
Hyphae with microconidia and tuberculate macroconidia in environment. Small intracellular yeasts inside macrophages.
Characteristics of Coccidioides immitis
Hypahe breaking up into arthroconidia is environmental form. Spherules with endospores is tissue form.
Characteristics of Blastomyces dermatitidis
Hyphae with nondescript conidia is environmental form. Broad-based budding yeats with double refractile cell wall in tissue.
Characteristics of Aspergillus fumigatus
Monomorphic fungus with septate hyphae and dichotomous branches at 45 degree angles
Characteristics of Candida albicans
Yeast is normal flora of mucous membranes. Germ tubes in serum. Pseudohyphae and true hyphae in tissues.
Characteristics of Cryptococcus neoformans
Encapsulated monomorphic yeast on India ink. Capsular "halo" in CSF sample.
Characteristics of Mucor
Nonspetate hyphae with 90 degree angle branches
Characteristics of Pneumocystis jirovenci
Obligate extracellular parasite shows silver-staining cysts in tissues.
Eastern Great Lakes
Histoplasma capsulatum
Ohio river valley
Histoplasma capsulatum, Blastomyces dermatitidis
Mississippi river valley
Histoplasma capsulatum, Blastomyces dermatitidis
Missouri river valley
Histoplasma capsulatum, Blastomyces dermatitidis
Southern California
Coccidioides immitis
Coccidioides immitis
New Mexico
Coccidioides immitis
Coccidioides immitis
Coccidioides immitis
Blastomyces dermatitidis
Northern Minnesota
Blastomyces dermatitidis
North Carolina
Blastomyces dermatitidis
South Carolina
Blastomyces dermatitidis
Central America
Blastomyces dermatitidis
Pityriasis/tinea versicolor
Malassezia furfur. Superficial infection of keratinized cells in moist, warm temperature. Hypopigmented spots on the chest and back. Rx.: topical selenium sulfide
Scaly, itchy ring-like lessions of the skin. Can also invade scalp, body and feet. Rx.: topical imidazoles.
Cutaneous sporotrichosis
Subcutaneous or lymphocutaneous mycetomas seen in gardeners, florists, basket weavers. Rx.: itraconazole or amphotericin B
Pulmonary sporotrichosis
Pulmonary mycetomas seen in urban homeless alcoholics. Rx.: itraconazole or amphotericin B
Fungus flu pneumonia
H. capsulatum. Histoplasmosis. Can be asymptomatic or pneumonia and hepatosplenomegaly may be present. Associated with spelunking (cave exploring), cleaning chicken coops or bulldozing starling roots. Rx.: ketoconazole, amphotericin B
Valley fever
Coccidioides immitus. Coccidiomycosis. Asymptomatic to self-resolving pneumonia associated with erythema nodosum and arthritis. Can affect immunocompromised patients with pulmonary calcifications or pregnant women in the third trimester. Rx.: amphotericin B.
B. dermatitidis. Acute or chronic pulmonary disease. Rx.: amphotericin B/ketoconazole
Allergic bronchopulmonary aspergillosis
A. fumigatus. Asthma and allergies predispose as it grows in mucous plugs
Fungus ball
A. fumigatus. Grows in lung cavitations need to surgically remove.
Invasive aspergillosis
A. fumigatus. Invades tissues causing infarcts and hemorrhage, pneumonia, meningitis or cellulitis. Neutropenia, CGD, CF and burns are predisposing factors. Rx.: amphotericin B
C. albicans. Oral thrush, esophagitis, gastritis (premature babies, steroid users, AIDS patients, antibiotic overuse). Yeast vaginitis (high pH, diabetics). Rx.: amphotericin B for disseminated, topical azoles/nystatin.
C. neoformans. Meningitis in Hodgkin and AIDS patients. Acute pulmonary infection in pigeon breeders. Rx.: AMB+5 flucytosine
Rhinocerebral infection
Mucor. Paranasal swelling, necrotic tissues and hemorrhagic exudates in ketoacidotic diabetics and leukemic patients. Rx.: amphotericin B
Pneumocystis pneumonia
Atypical pneumonia in AIDS patients. Nonproductive cough, fever, dyspnea, destruction of type I pneumocytes. Patchy infiltrate in x-ray. Rx.: trimethrophrim sulfa
Normal flora of cutaneous surfaces
Staph epidirmidis, staph aureus, strep
Normal flora of the nose
Staph aureus
Normal flora of the oropharynx
Viridans strep, strep mutans, nonpathogenic Neisseria, nontypable H. influenzae
Colon normal flora
anaerobic bacteroides, gram- anaerobic rods
Normal flora of the vagina
Encapsulated bacteria
Strep pneumonia, Klebsiella, Haemophilus, Pseudomonas, Neisseria menigitidis, Cryptococcus neoformans. "Some Killers Have Pretty Nice Capsules"
Teichoic acids
Adherence and pathogenicity factor of gram positive bacteria
Adherence and antiphagocytic component of gram negative bacteria (specially N. gonorrehae)
M protein
Strep pyogenes (group A β-hemolytic) antiphagocytic surface component
A protein
Staph aureus virulence factor binds Fc portion if IgG and inhibits opsonization and phagocytosis
IgA protease
Destructs mucosal IgA. Produced by Neisseria, Haemophilus, S. Pneumoniae
Gram negative membrane component endotixin. Heat-stable, not immunogenic. Lipid A is toxic component.
LPS activates macrophages with release of TNF-α, IL-1 (fever), IL-6, nitric oxide with tissue damage. Damage endothelium releases bradykinin which causes vasodilation and shock. Hageman facctor activates coagulation cascade in DIC. Activates complement C3a (hypotension, edema) and C5a (neutrophil chemotaxis).
Define: superantigen
Crosslinks MHC-II and T-cell receptor simultanously and non-specifically which leads to polyclonal activation of T-cells with massive release of IFN-γ which activates macrophages to release IL-1, TNF-alpha and IL-6 and an exagerated reaction
Diptheria toxin
C. diptheriae. ADP ribosylation and inactivation of EF-2 inibits eukaryotic protein synthesis in throat epithelium, heart, nerves. Causes pharyngitis with a pseudomembrane in throat
Exotoxin A
Pseudomonas. ADP ribosylation and inactivation of EF-2 inibits eukaryotic protein synthesis mainly in hepatocytes
Shiga toxin
Shigella. Cleaves 60S ribosomal subunit, inhibits protein synthesis
E.coli O157. Cleaves 60S ribosomal subunit, inhibits protein synthesis. Causes HUS
Tetanus toxin
C. tetani. Blocks release of inhibitory neurotransmitters GABA and glycine. Lockjaw, muscle spasms
Botulinum toxin
C. botulinum. Blocks release of Ach causing anticholinerginc symptoms, flaccid paralysis. Spores found in honey.
Staph aureus superantigen causes toxic shock syndrome (fever, rash, shock)
Staph aureus. Food poisoning 2-6 hours after ingestion of mustards.
Strep exotoxin A
Erythrogenic toxin. Causes toxic shock-like syndrome (fever, rash, shock) and cardiotoxicity
Heat labile toxin
Enterotoxigenic E. coli. Stimulates Adenylate cyclase by ADP ribosylation, increases cAMP. Secretory watery "traveler's" diarrhea. "Labile like the Air, stable like the Ground"
Heat stable toxin
Enterotoxigenic E. coli. Stimulates Guanylate cyclase by ADP ribosylation increases cAMP. Secretory watery diarrhea. "Labile like the Air, stable like the Ground"
Cholera toxin
Vibrio cholera. ADP ribosylateion of Gs stimulates adenylate cyclase and cAMP increasing Cl- secretion and decreasing Na+ reabsorption in the intestines. Causes profuse "rice water" diarrhea.
Anthrax toxin
Bacillus anthracis. EF component is an adenylate cyclase, increases cAMP. Causes edema and cell lysis
Pertussis toxin
Bordetella pertussis/ ADP ribosylates Gi, the negative inhibitor of adenylate cyclase, increasing cAMP. Whooping cough, lymphocytosis, hypoglycemia
Perfringens α-toxin
C. Perfringens. Lecithinase causes myonecrosis and gas gangrene. Double zone of hemolysis on blood agar
Gram positive cell envelope components
Capsule; thick peptidoglycan cell wall gives rigid support and protects from osmotic damage; teichoic acids; cytoplasmic inner membrane
Gram negative cell envelope components
Capsule; Outer membrane contains LPS/lipid A; thin prptidoglycan cell wall; periplasmic space contains β-lactamases; inner cell membrane
Describe the Gram stain
Crystal violet and Gram's iodine stain dark blue; acetone washes it off from gram negatives; safranin stains gram negatives red
Describe Ziehl-Neelsen acid fast stain
Carbol fuchsin with heat stains red; acid alcohol washes it off from non-acid fast; methylene blue stains non-acid fast blue
Culture media: Corynebacterium
Loffler's, tellurite
Culture media: lactose-fermenting enterobacteria
Pink colonies on MacConkey's agar. "Lactose is the Key"
Culture media: vibrio cholerae
Alkaline TCBS
Culture media: legionella
Charcoal-yeast extract with cysteine
Culture media: Mycobacterium
Lowenstein-Jensen medium
Culture media: Neisseria and Haemophilus
Chocolate agar with factors V and X
Culture media: Neisseria from sites with normal flora
Thayer-Martin selective medium
Obligate aerobes
Nocardia, Pseudomona, Mycobacterium tuberculosis, Bacillus. "Nagging Pests Must Breathe"
Obligate anaerobes
Actinomyces, Bacteroides, Clostridium. "Anaerobes know their ABCs"
Intracellular pathogens
Rickettsia, chlamydia
Urease-positive bugs
H. pylori, proteus, klebsiella, ureaplasma
Characteristics of Staph aureus
Gram+ cocci in clusters, catalase+, coagulase+, β hemolytic, ferments mannitol, salt tolerant
Characteristics of Staph epidirmidis
Gram+ cocci in clusters, catalase+, coagulase-, novobiocin sensitive
Characteristics of Staph saprophyticus
Gram+ cocci in clusters, catalase+, coagulase-, novobiocin resistant
Characteristics of S. pneumoniae
Gram+ catalase- lancet-chapes diplococci in chains, α hemolytic, "MOPS" optochin sensitive, bile soluble, +quellung
Characteristics of Viridans strep
Gram+ catalase- cocci, α hemolytic, optochin resistant, bile insoluble
Characteristics of S. pyogenes
Gram+ catalase- cocci, group A, β hemolytic, bacitracin sensitive, PYR+
Characteristics of S. agalactiae
Gram+ catalase- cocci, group B, β hemolytic, bacitracin resistant, cAMP test+
Characteristics of Enterococcus
Gram+ catalase- cocci, PYR+, hydrolizes esculin in 40% bile and 6.5% NaCl
Characteristics of Clostridium tetani
Gram+ spore-forming anaerobic rods
Characteristics of Clostridium botulinum
Gram+ spore-forming anaerobic rods
Characteristics of Clostridium perfingens
Gram+ spore-forming anaerobic rods, double zone of β hemolysis
Characteristics of Clostridium difficile
Gram+ spore-forming anaerobic rods
Characteristics of Corynebacterium diptheriae
Gram+ aerobic club-shaped rods, V or L shapes on tellurite, metachromatic granules on Leoffler. β-prophage contains diptheria toxin gene (lysogeny)
Characteristics of Bacillus
Gram+ spore-forming aerobic rods
Characteristics of Listeria
Gram+ rods with tumbling or actin jet motility, β hemolytic, cold growth, facultative intracellular
Characteristics of Actinomyces
Gram+, long branching filaments, non-acid fast anaerobic rods
Characteristics of Nocardia
Gram+, long branching filaments, partially acid-fast aerobic rods
Characteristics of Mycobacterium tuberculosis
Acid-fast aerobic rods on Lowenstein-Jensen medium, auramine-rhodamine stainning (fluorescent apple green). Mycolic acid lipids on cell wall
Characteristics of Mycobacterium lepreae
Acid-fast aerobic rods, can't be cultured (obligate intracellular). Mycolic acid lipids on cell wall
Characteristics of Neisseria meningitidis
Gram- kidneybean-shaped diplococci, grows on chocolate agar, maltose fermenter, polysaccharide capsule
Characteristics of Neisseria gonorrhoeae
Gram- kidneybean-shpaed diplococci, growws Thayer-Martin, maltose non-fermenter, no polysaccharide capsule
Characteristics of Haemophilus influezae
Gram- cocobacillus, requires factor X and V (chocolate agar). Satellite phenomenon near staph aureus on blood agar
Characteristics of Pasteurella
Gram- cocobacillus, anaerobic
Characteristics of Brucella
Gram- cocobacillus, aaerobic, zoonosis, biowarfare
Characteristics of Bordetella pertussis
Gram- aerobic cocobacillus
Characteristics of Klebsiella
Gram- lactose-fermenting rods on MacConkey, polysacchride capsule, oxidase-
Characteristics of E. coli
Gram- lactose-fermenting rods on MacConkey, oxidase-
Characteristics of Shigella
Gram- nonlactose-fermenting rods on MacConkey, nonmotile, no H2S production, oxidase-
Characteristics of Salmonella
Gram- nonlactose-fermenting rods on MacConkey, highly motile, H2S producer, oxidase-
Characteristics of Proteus
Gram- nonlactose-fermenting rods with swarming motility, H2S producer, urease+, oxidase-
Characteristics of Pseudomonas
Gram- nonlactose-fermenting rods on MacConkey oxidase+, aerobic, produces green pigment pyocyanin
Characteristics of C. jejuni
Gram- nonlactose-fermenting curved rods with flagella, oxidase+, microaerophillic
Characteristics of H. pylori
Gram- nonlactose-fermenting helical rods with flagella, oxidase+, urease+, microaerophillic
Characteristics of Vibrio cholera
Gram- nonlactose-fermenting curved rod with flagella, oxidase+ grows on alkaline media (thiosulfate)
Characteristics of Francisella
Gram- facultative intracellular rods, zoonosis, biowarfare
Characteristics of Yersinia
Gram- coagulase+ rods with bipolar stainnning, facultative intracellular, zoonosis
Characteristics of Gardnerella
Gram variable rod, positive whiff fishy smell test
Characteristics of Bacteroides
Gram- anaerobic rod
Characteristics of Treponema
Gram- spirochete, spiral-shaped with axial filaments, dark microscopy
Characteristics of Borrelia
Gram- spirochete, spiral-shaped with axial filaments, microaerophilic
Characteristics of Leptospira
Gram- spirochete, spiral question mark-shaped with axial filaments
Characteristics of Rickettsia
Gram- (doesn't stain well) obligate intracellular rods
Characteristics of Coxiella
Gram- (doesn't stain well) obligate intracellular rods
Characteristics of Chlamydia
Obligate intracellular bug seen in Giemsa stain. Wall lacks muramic acid. Elementary body is infective, reticulate bodies are replicating in the cell
Characteristics of Mycoplasma
Lacks peptidoglycan cell wall, does not gram stain. Cholesterols in membrane
Staph gastroenteritis
Nausea, abdominal pain, vomiting, followed by diarrhea 2-6 hours after ingesting enterotoxin in custards, pastries, potato salad, canned meats
Infective acute endocarditis
Staph aureus. Fever, malaise, leukocytosis, murmur
Abscess and mastitis
Staph aureus. Pain, pus, redness, edema, warmth.
Toxic shock syndrome
Staph aureus or GAS. Fever hypotension, scarlatiform desquamating rash on palms and soles, multiorgan failure. Produced by superantigen TSST-1 toxin
Staph aureus or GAS. Erythematous papules to bullae (staph) or honey-crusted lessions (GAS)
Staph pneumonia
Typical acute severe pneumonia. Associated to Ccystic Phibrosis, CGD
MCC surgical infections
Staph aureus. Fever with cellulitis or abscess
MCC osteomyelitis
Staph aureus. Bone pain, fever, inflammation, lytic bone lessions on x-rays
"Honeymoon" cystitis
Staph saprophyticus. 2nd MCC UTI in sexually active women. Dysuria, frequency, urgency, suprapubic pain.
3 MCC of ambulatory UTIs
E. coli, S. saprophyticus, Klebsiella
Infection of prosthetic devices and catheters
Staph. epidirmidis
Rx.: staph infections
Nafcillin, oxacillin. For MRSA: vancomycin
GAS. Abrupt onset of sore throat, fever, tonsillar abscesses, tender anterior cervical nodes. Rx.: penicillin or macrolide in case of allergy
Scarlet fever
GAS. Pharyngitis plus sandpaper rash (palm and soles spared), strawberry tongue, nausea
Rheumatic fever
Antibodies against GAS M protein cross-react with heart two weeks after a pharyngitis (Type II hypersensitivity). Jones major criteria: Fever, subcutaneous nodules, polyarthritis, carditis, erythema marginatum, chorea.
Acute postsrep glomerulonephritis
GAS M12 serotype. Immunocomplex deposition on GBM (type III hypersensitivity). Nephritic syndrome: hypertension, azotemia, edema, smoky urine (hematuria).
3 MCC of neonatal meningitis
GBS agalactiae, E. coli, Listeria
Diseases caused by Strep pneumoniae
MOPS: Meningitis, Otitis media (in children), Penumonia, Sinusitis; sepsis in asplenic sickle cell anemia.
Strep pneumonia virulence factors
Polysacchride capsule is major factor, IgA protease cleaves mucosal IgA, teichoic acids and peptidoglycan are highly inflammatory in CNS
Clinical features of typical pneumonia and Rx.
High fever, dyspnea, tachypnea, pleuritic chest pain, productive rusty sputum cough, lobar consolidation on x-ray. Rx.: macrolides
Pathophysiology of Strep. Viridans infection
Dextran biofilm mediated adherence to teeth or fibrin deposits in damaged/prosthetic heart valve and growth in vegetations. Causes dental caries and subacute endocarditis.
Subacute bacterial endocarditis
Strep viridans following dental work. "FROM JANE": fever, Roth retinal lessions, Osler painful nodules, murmur, Janeway painless lessions, anemia, nailbed hemorrhages, emboli. Rx.: penicillin G with aminoglycosides
Disease caused by enterococcus
Urinary/billiary tract infections and subacute bacterial endocarditis following prostate or GI surgery
Malignant pustule
Cutaneous anthrax by B. anthracis. Painless ulcer papule with vesicles have a central eschar necrosis with erythematous border and painful regional lymphadenopathy
Wool sorter's disease
Life-threatening pneumonia by B. anthracis on contact with animal hides. Cough, fever, facial edema, dyspnea, diaphoresis, cyanosis and shock with mediastinal hemorrhagic lymphadenitis
Bacillus gastroenteritis
Rapid onset gastroenteritis with watery diarrhea associated with reheated fried rice
C. tetani. Risus sardonicus (lock jaw), opisthotonus, extreme muscle spasms caused by tetanosmin block of inhibitors glycine and GABA. Rx.: Hyperimmune gamma globulin, metronidazole, diazepam
Disease caused by C. botulinum
"Floppy baby" flaccid paralysis by botulinum toxin block of acetylcholine at neuromuscular junction. Flaccid paralysis, diplopia, dysphagia, disphonia. Associated with honey and canned vegetables
Gas gangrene
C. perfringes. Dirty wound with increasing pain, edema, gas, fever and tachycardia. Caused by alpha toxin which is a lecithinase that lyses tissue
Clostridium food poisoning
Enterotoxin in reheated meat dishes causes noninflammatory watery diarrhea in 8-24 hours
Pseudomembranous colitis
C. difficile enterotoxin damages mucosa. Diarrhea, colitis, pseudomembrane. Associated with clindamycin use in hospitalized patients. Tx.: metronidazole
MCC of meningitis in renal transplant or cancer patients
Granulomatosis infactisepticum
Neonatal sepsis with disseminated granulomas after in-uterus transmission of Listeria. Associated with unpasterurized milk products, cold deli meats, soft cheeses.
Diptheria toxin inhibits EF-2 and protein synthesis. Causes pharyngitis with gray pseudomembrane. Complications are larynx obstruction, myocarditis, recurrent laryngeal nerve palsy
Oral/facial draining abscesses with sinus tracts in tissues with low oxygenation: cervicofacial, pelvic, solitary brain abscess
Cavitary pulmonary mycetomas in immunocompromised and cancer patients. Cough, fever, dyspnea, cavitations.
Pathophysiology of tuberculosis
Primary TB: replication in macrophages with subsequent CMI produces Gohn focus which is transported to hilar lymph nodes remaining latent. Secondary TB: a reinfection or immunocrompromise produces granulomas and cavitary lessions or disseminated milliary TB (CNS, vertebrae, kidneys GI).
M. tuberculosis pathogenic factors
Sulfatides in cell envelope inhibit phagosome lysosome fusion. Tuberculin induces CMI with casseating granulomas.
Clinical features of TB
Chronic productive cough, hemoptysis, weight loss
M. leprae invades nerve endings producing a strong CMI with granulomas (tuberculoid leprosy) or a weak CMI in which theres bacterial damage to nerves. Paresthesia (leads to trauma and burns), loss of eyebrows, destruction of nasal septum, lumpy ears, leonine features.
Meningococcus virulence factors
Polysacchride capsule is antiphagocytic; IgA protease allow oropharynx colonization; endotoxin leads to septic shock in meningococcemia; deficiency of C5-C8 predisposes to bacteremia
Meningococcemia and meningitis
N. meningitidis. Abrupt onset of fever, chills, prostration and petecchial rash, nuchal rigidity. CSF: high pressure, high neutrophils, high protein, low glucose.
Waterhouse-Friderichsen syndrome
Meningococemia leads to ecchymoses, DIC, bilateral adrenal infarct, shock, death.
Diseases caused by N. gonorrheae
Uretheral/vaginal leukorrhea; endocervicitis/PID; septic arthritis; neonatal opthalmia
Diseases caused by pseudomonas
"PSEUDOmonas": Pneumonia in CF and CGD; Sepsis with black necrotic lessions; External otitis "swimmer's ear"; UTI in catheterized patients; Diabetes and Drug-user Osteomyelitis. Associated with burns and wound infections; associated with respirators, humidifiers and water.
Legionnaires disease
Legionella. Atypical pneumonia associated with old age, immunosuppressed, smokers, water aerosols and air conditioning systems.
Francisella. Dermacentor tick bite produces ulceroglandular disease with ulcer at bite site and lymph node enlargement and necrosis. Associated with rabbit skinning in Arkansas and Missouri.
Whooping cough
B. pertussis. Repetitive cough with inspiratory whoops, anoxia and eye hemorrhages in unvaccinated children
Brucellosis/undulant fever
Brucella. Acute septicemia with high fever, profuse sweating and hepatomegaly. Associated with slaughterhouse animals and unpasteurized dairy products in California, Texas or travel to Mexico
Campylobacter gastroenteritis
MCC of inflammatory diarrhea in US. Abdominal pain, vomitting, bloody diarrhea with fecal leukocytes. Complication: Guillain-Barre syndrome due to cross-reactivity between Campylobacter oligosacchrides and neural glycosphingolipids.
Guillain-Barre syndrome
Inflammatory demyelinating polyneuropathy caused by antibodies against Campylobacter (or other agents) cross reacting with neural glycosphingolipids. Acute onset of ascending paralysis with areflexia.
Helicobacter virulence factors
Motile flagella; Urease covers the bug in ammonium which neutralizes stomach acid; Mucinase aids in penetrating the mucin layer of stomach.
Diseases associated with Helicobacter
Chronic gastritis and 90% of duodenal peptic ulcers; gastric adenocarcinoma., gastric MALToma
E. coli serotypes
"PITCH": EPEC (enteropathogenic=pediatric); EIEC (enteroinvasive=inflammatory diarrhea); ETEC (enterotoxigenic=traveler's diarrhea); EHEC (enterohemorrhagic=undercooked hamburgers)
E.coli. Colonization of uroepithelium from fecal flora. Pyelonephritis-associated pilli (p. pili) is major virulence factor and allows adherence to uroepithelium
2nd MCC neonatal septicemia
E. coli from maternal fecal flora infects neonate during parturition. K1 serotype capsule and endotoxin are virulence factors
3 MCC nosocomial UTIs
E. coli, proteus, klebsiella
MCC gram- sepsis
E. coli. From indwelling IV catheters
Traveler's diarrhea
E coli. Associated with travel to third-world countries and children < 3 in third-world countries. Watery diarrhea produced by LT and ST toxins that stimulate adenylate cyclase and guanylate cyclase increasing cAMP.
2nd MCC of infantile diarrhea
EPEC (enteroPathogenic=Pediatric). Noninflamatory watery diarrhea in babies in developing countries. Adherance to M cells is virulence factor.
Diseases by EHEC
Bloody diarrhea without leukocytes in stool or fever (distinguishes from shigellosis). Can cause HUS. Verotoxin shiga-like toxin inhibits protein synthesis by interfering with 60S ribosomal subunit.
Disease caused by EIEC
Watery inflammatory diarrhea with fever and fecal leukocytes
Shigella virulence factors
Endotoxin; invasion of M cells and polymeriazation of actin jet trails produce shallow ulcers; shiga toxin inhibits protein synthesis by interfering with 60S ribosomal subunit
1-10 acid-resistant organisms needed for infection. Invasive bloody diarrhea with fever, abdominal cramps, tenesmus.
Diseases caused by K. pneumoniae
Typical pneumonia in alcoholics and diabetics with currant-jelly bloody sputum and lung abscesses. Nosocomial UTIs (3rd MCC) related with catheters. Septicemia in immunocompromised patients.
Granuloma inguinale
Subcutaneous nodules on genitals with bleeding ulcers. Caused by K. granulomatis. Associated with Caribbean and New Guinea patients. Donovan bodies encapsulated bacteria inside macrophages
Typhoid fever
Salmonella typhi. Large number of organisms ingested infect ileocecal region cause constipation. Bacteria reach basolateral side of M cells, lymph nodes and blood with positive blood culture at 1 week. Infection of liver and spleen with fever, headache and septicemia. 85% of stool cultures postive by week 3. Complication: necrosis and perforation of Peyer patches.
MCC inflammatory diarrhea
Campylobacter, salmonella enterica
MCC infantile diarrhea
Rotavirus, EPEC
Diseases caused by Salmonella enterica
Gastroenteritis with nausea, vomiting, abdominal pain, occasionally bloody stools; MCC osteomyelitis in sickle cell anemia patients. Associated with reptile pets and poultry.
Bubonic plague
Yersinia pestis. Rapidly increasing fever, regional buboes, conjunctivitis, pneumonia. Highly contagious zoonosis associated with rodents and prairie dogs.
Yersinia enterocolitis
Inflammatory bloody diarrhea, fever, pseudoappendicitis. Associated with cold northern climates (Michigan, Scandinavia), unpasteurized milk and pork, pet puppies.
Disease associated with proteus
2nd MCC nosocomial UTIs, struvite renal stones due to urease.
Weil-Felix reaction
Anti-rickettsial antibodies cross-react with proteus antigens. Positive for Rocky Mountain spotted fever (ricketsia rickettsi) and typhus (rickettsia typhi). Negative for Q fever (coxiella)
Gardnerella vaginosis
Vaginal fishy odor and thin gray vaginal discharge. Caused by reduction of vaginal Lactobacillus when vaginal pH > 4.5. Find clue cells.
Vibrio cholerae. Profuse rice watery diarrhea and dehydration. Cholera toxin ADP ribosylates Gs increasing adenylate cyclase and cAMP with efflux of Cl- and H2O.
Disease caused by Pasteurella
Cellulitis and lymphadenitis associated with cat bites
Disease caused by Haemophilus influenzae
"haEMOPhilus": Epiglotitis (MCC); Meningitis in unvaccinated children (MCC); Otitis media; Pneumonia in COPD patients.
Painful chancroid
Haemophilus ducreyi. Chancroid and soft painful genital ulcers
Diseases caused by Bacteroides
Septicemia, peritonitis, abdominal abscess after trauma or emergency abdominal surgery
Primary syphilis
T. pallidum. Painless indurated chancre, highly contagious, heals in 3-6 weeks.
Secondary syphilis
T. pallidum. Condylomata lata flat wartlike perianal and mucous membrane lessions, highly contagious. Maculopapular rash
Tertiary syphilis
T. pallidum. Gumman (syphilitic granulomas); aortitis and syphilitic aneurysms (obliterative endarteritis of vasa vasorum); tabes dorsalis (ataxia, Romberg+); "Prostitute" pupil "accomodates but does not react"
Congenital syphilis
Stillbirth, keratitis, deafness, desquamating maculopapular rash
VDRL test
Antitreponemal antibodies in 1ary and 2dary syphilis cross-react with cow heart antigens. Sensitive but not specific.
FTA-ABS test
Fluorescent antibodies agglutinate treponema sample. Specific for syphilis.
Lyme disease
Ixodes deer ticks transmit Borrelia. Bull's eye erythema migrans; severe headache, meningitis, Bell palsy; arrhythmias and miocarditis; migratory poliarthritis. Associated with northeastern states.
Myalgia, abdominal pain, hepatitis with combined jaundice. Associated with urine-contaminated waters (jet skiers and sewer workers)
Rocky Mountain spotted fever
R. rickettsii transmitted by tick dermacentor. Fever, headache and maculopapular to petechial rash begins in wrists and ankles and spreads to trunk (centripetal rash). Associated with east coast mountains. Weil-Felix+
Q fever
Coxiella. Fever, pneumonia and granulomatous hepatitis. Weil-Felix negative
MCC of bacterial STD
Chlamydia trachomatis serotypes D-K
Diseases caused by chlamydia trachomatis
Serotypes D-K cause urethritis, cervicitis, PID and infertility, inclusion conjunctivitis; Lymphogranuloma venereum and genital elephatiasis in Africa, Asia, South America. Serotypes A, B, C follicular conjunctivitis with corneal scarring and blindness.
3 MCC of atypical pneumonia
Mycoplasma, Legionella, Chlamydia pneumoniae
Walking pneumonia
Mycoplasma. MCC of pneumonia in adults 18-40 years. Atypical pneumonia with persistent hacking cough and no sputum.
What is a plasmid?
Extra chromosomal genetic elements non-essential for life. Contain genes for fertility, antibiotic resistance and exotoxins.
What is a bacteriophage?
Prophage (bacterial virus) DNA is stable inside the bacterial chromosome (temperate phage). Usually encodes virulence factors such as exotoxins. Temperate phages = lysogeny.
What is a transposon?
Mobile genetic elements (jumping genes). From plasmid to chromosome or vice versa. Ususally associated with multiple drug resistance genes.
What is homologous recombination?
Incorporates and stabilizes genes acquired by transformation, conjugation or transduction. A linear sequence of DNA is exchanged into a homologous or similar sequence of the bacterial chromosome. DNA outside the bacterial chromosome is lost.
What is site-specific recombination?
Integration of circular pieces of DNA (plasmids, phages, transposons) into the bacterial chromosome. No homology is required, no DNA is lost.
What is transformation?
DNA is taken up from the environment by competent bacteria and incorporated by homologous recombination.
F+ x F- conjugation
F+ contains conjugation genes. Sex pilus coded by F+ plasmid tranfers plasmid to F- cell. No chromosomal genes are transferred.
Hfr x F- conjugation
Hfr cell has plasmid integrated into the chromosomal DNA which is transferred to F- cell along with chromosomal DNA.
Generalized transduction
A lytic phage acquires some bacterial DNA and carries to the next bacteria after lysis. Any gene can be transduced.
Specialized transduction
A temperate lysogenic phage carries a mistankenly excised flanking chromosomal gene to the next bacteria. Only specific flanking genes are transferred with phage.
Steam under 15lbs pressure at 121 degrees celsius for 15-20 minutes. Or dry heat for 2 hours at 180 degrees celsius.
Membrane damaging disinfectants
Use for enveloped viruses: detergents (benzalkonium), alcohol, phenols
Protein denaturing disinfectants
Use for naked capsid viruses. Chlorine, iodine, H2O2, formaldehyde, alkylating agents.