What is the toxic component of LPS?
Lipid A
What does the pilus/fimbria do and give an example
Mediates adherence of bacteria to cell surface as in meningococcus colonizing the pharyngeal surface
Bacteria with unusual cell membranes/walls
Mycoplasma - membrane contains sterols, no cell wall. Mycobacteria - contain mycolic acid, high lipid content
Bugs that do not gram stain well
These Rascals May Microscopically Lack Color. Treponema, Rickettsia, Mycobacteria, Mycoplasma, Legionella, Chlamydia
Stain for legionella
Silver stain
Organisms seen with giemsa stain
Borrelia, plasmodium, trypanosomes, chlamydia
Organisms seen with PAS stain
Stains glycogen and mucopolysaccharides. Use to diagnose Whipples disease
Organisms seen with silver stain
Fungi and legionella
Culture requirements of h flu
Chocolate agar. Factor V (NAD) and Factor X (hematin). If grown with staph they will provide the needed NAD
Culture requirements of n gonorrhoeae
Thayer-Martin (VPN). Vancomycin, Polymyxin, Nystatin. Or Vanco, Colistin, Nystatin, Trimethoprim
Culture requirements of b pertussis
Bordet-Gengou (potato) agar
Culture requirements of c diphtheriae
Tellurite plate, Lofflers media
Culture requirements of m tb
Lowenstein-Jensen agar
Culture requirements of m pneumoniae
Eatons agar
Culture requirements of lactose-fermenting enterics
Will be pink on MacConkey. E coli also grown on Eosin-Methylene Blue (EMB) and will be green with metallic sheen
Culture requirements of legionella
Charcoal yeast extract agar buffered with cysteine and iron
Culture requirements of fungi
Sabourauds agar
What is another name for polymixin?
Colistin
What allows e coli to spread hematogenously and cause meningitis?
K-1 capsule
Encapsulated bacteria (6)
Strep pneumo, H flu type b, N meningitidis, Salmonella, Klebsiella, group B strep
What vaccines should you give an asplenic patient?
S pneumo, H flu, N meningitidis
Test of choice for encapsulated bacteria
Quellung (will see capsular swelling)
Catalase-positive organisms (5)
S aureus, Serratia, Pseudomonas, Candida, E coli
What is the antigen in the N meningitidis vaccine?
Capsular polysaccharide
Urease positive bugs (8)
Proteus, Ureaplasma, Nocardia, Cryptococcus, H pylori, Klebsiella, Staph saprophyticus, Staph epidermis
Protein A virulence factor
Staph aureus. Binds Fc of Ig. Prevents opsonization and phagocytosis
IgA protease
Cleaves IgA. Secreted by s. pneumoniae, h flu type b, and neisseria
M protein
Group A streptococcus. Helps prevent phagocytosis
Where are exotoxin and endotoxin genes respectively located?
Exotoxins - plasmid or bacteriophage, endotoxin - bacterial chromosome (remember that endotoxins are part of bacterial wall, thus part of bacteria themselves. Similarly the gene is in with bacterial genes)
Heat stability of exotoxins and endotoxins respectively
Exotoxins destroyed rapidly at 60 C (except staph enterotoxin), endotoxins stable at 100 C for 1 hour
Diseases caused by exotoxins and endotoxins respectively
Exotoxins - tetanus, botulism, diphtheria. Endotoxins - meningococcemia, gram negative sepsis
Diphtheria toxin
Inactivates EF-2 and thus inhibits protein synthesis
Exotoxin A
Pseudomonas. Inactivates EF-2 (like diphtheriae toxin) and thus inhibits protein synthesis
Shiga Toxin
Shigella. Inactivates 60S ribosome by cleaving rRNA (like EHEC toxin). Causes GI mucosal damage and triggers HUS
Shiga-like Toxin
EHEC (including O157H7). Inactivates 60S ribosome by cleaving rRNA. Enhances cytokine release, causes HUS but EHEC does not invade host cells (unlike shigella)
What are the properties of EHEC in culture?
Does not ferment sorbitol, does not produce glucuronidase
Heat-labile (cholera-like) toxin
ETEC. Overactivates adenylate cyclase increasing Cl secretion. Watery diarrhea.
Heat-stable diarrhea
ETEC and Yersinia enterocolitica. Overactivates guanylate cyclase. Decreases reabsorption of NaCl and water in gut. Watery diarrhea in ETEC, bloody in y entocolitica (invades)
Edema factor
Bacillus anthracis. Mimics adenylate cyclase (similar to pertussis toxin). Black eschar of cutaneous anthrax
Cholera toxin
Vibrio cholerae. Overactivates adenylate cyclase by permanently activating Gs. Increased Cl secretion. Rice-water diarrhea
Pertussis toxin
Bordatella pertussis. Overactivates adenylate cyclase by disabling Gi. Impairs phagocytosis.
Tetanospasmin
Clostridium tetani. Cleaves SNARE (required for NT release). Prevents release of inhibitory NTs in spinal cord (GABA and glycine). Rigidity and lockjaw
Botulinum toxin
Clostridium botulinum. Cleaves SNARE (required for NT release). Prevents stimulatory (Ach) signals at neuromuscular junction. Flaccid paralysis
Botulinum toxin
Clostridium botulinum. Cleaves SNARE (required for NT release). Prevents stimulatory (Ach) signals at neuromuscular junction. Flaccid paralysis
Alpha toxin
Clostridium perfringens. A phospholipase that degrades tissue and cell membranes. Causes gas gangrene and hemolysis
Streptolysin O
Strep pyogenes. Protein that degrades cell membranes. Lyses RBCs (beta hemolysis). Use ASO in diagnosis of rheumatic fever
Exotoxin A
Strep pyogenes. Superantigen (MHC 2 and TCR linking). Toxic shock syndrome
Toxic shock syndrome toxin (TSST-1)
Staph aureus. Superantigen (MHC 2 and TCR linking). Toxic shock syndrome
Transformation (including bacteria capable of it)
Ability to take up DNA from environment. Strep pneumo, h flu type b, neisseria
Conjugation
F+ to F- (plasmid DNA only) or Hfr to F- (plasmid and chromosomal genes)
Transposition
Transfer of genes between plasmids or between chromosome and plasmid. Plasmid DNA may then move between bacteria
Generalized transduction
Lytic phage infection with accidental packing of bacterial chromosome into viral capsid. Viral transfer
Specialized transduction
Lysogenic phage incorporates and takes bacterial DNA with it when it excises
What toxins are encoded in lysogenic phages (specialized transduction)?
Shiga-like toxin, Botulinum toxin, Cholera toxin, Diphtheria toxin, Erythrogenic toxin of strep pyogenes
Branching gram positive bacteria and what separates them
Actinomyces (anaerobe and not acid fast), Nocardia (aerobe, acid fast)
Catalase positive and negative gram positive cocci
Positive - Staph (clusters), Negative - Strep (chains)
Coagulase positive, catalase positive gram positive cocci
S aureus (beta hemolytic)
Coagulase negative, catalase positive, gram positive cocci
Novobiocin sensitive - staph epidermis, novobiocin resistant - staph saprophyticus
What do staph epidermis tend to infect?
Teflon coated surfaces (due to biofilm formation) such as IVs and other artifical surfaces
Alpha hemolytic catalase negative gram positive cocci
Optochin sensitive - strep pneumo (bile soluble - does not grow in bile). Optochin resistant - Viridans strep (eg strep mutans, insuluble in bile)
Beta hemolytic catalase negative gram positive cocci
Group A (Bacitracin sensitive) - Strep pyogenes (impetigo). Group B (bacitracin resistant) - Strep agalactiae
Gamma hemolytic catalase negative gram positive cocci
Enterococci (e faecalis) - grow in 6.5 pct NaCl and bile. Nonentercocci (strep bovis) - grow in bile but not 6.5 pct NaCl
Gram positive mnemonics
Staph (novobiocin) - On offices STAPH retreat there was NO StRES. Strep (optochin) - OVRPS. Strep (bacitracin) - B-BRAS
Hemolysis of listeria monocytogenes
Beta
What is the most common site of staph aureus colonization?
Anterior nares
What is strep pneumo the most common cause of?
Meningitis, Otitis media in children, Pneumonia, Sinusitis
Color of sputum in strep pneumo infection
Rust colored
Strep viridans infections
Dental caries (strep mutans), subacute bacterial endocarditis of damaged valves (strep sanguis)
What infection precipitates rheumatic fever?
Group A strep (strep pyogenes)
What is done to prevent group B strep infection in newborns?
Pregnant women screened at 35-37 weeks. Positive patients receive intrapartum penicillin
What do enterococci cause?
UTI and subacute endocarditis. Are normal colonic flora. Are penicillin G resistant
Strep bovis
Normal gut bacteria. Can cause bacteremia and subacute endocarditis in colon cancer patients
Gram positive rods with metachromatic (blue and red) granules and Elek test for toxin
Cornyebacterium diptheriae
Gram positive rods with metachromatic (blue and red) granules and Elek test for toxin
Cornyebacterium diptheriae
What is seen in diphtheriae pharyngitis
Grayish-white pseudomembrane and lymphadenopathy
What is needed to prevent clostridium tetani infection and what is the implication of this?
IgG. Breastmilk will not cut it. Vaccinate early
Path tetanospasmin travels
Wound to motor neuron axon to spinal cord
Toxin A and Toxin B
C difficile. A (enterotoxin) - binds brush border of gut. B (cytotoxin) - destroys enterocyte cytoskeleton, causing pseudomembranous colitis
How do you diagnose C difficile colitis?
Detection of Toxin A and/or B in the stool
Cause and treatment of C difficile
Commonly caused by clindamycin or ampicillin. Treat with metronidazole or oral vanco
What is given to prevent neonatal tetanus?
A maternal vaccine during pregnancy
Only bacterium with a polypeptide capsule (contains D-glutamate)
Bacillus anthracis
Fever, pulmonary hemorrhage, mediastinitis, shock
Pulmonary anthrax
Microscopy of anthrax infection
Long chains (medussa head appearance)
People in what profession are susceptible to anthrax infection?
Woolsorters
Culture appearance of listeria monocytogenes
Narrow zone of beta hemolysis on sheep blood agar
Where does listeria monocytogenes live?
Facultative intracellular
Amnioitis, septicemia, and spontaneous abortion. Or granulomatosis infantiseptic. Or neonatal meningitis. Or meningitis in immunocompromise. Or mild gastroenteritis (healthy adult)
Listeria
Treatment for listeria
Usually self-limited. Ampicillin in infants and immunocompromised
Treatment for branching gram positive rods
SNAP. Sulfa for Nocardia, Actinomyces use Penicillin
Prophylactic treatment for MAIC in AIDS patients
Azithromycin
Fevers, weight loss, weakness, hepatosplenomegaly
MAI
Treatment for leprosy
Dapsone (toxicity is hemolysis and methemoglobinemia)
Outcomes of leprosy
Lepromatous (Th2 response), tuberculoid (Th1 response)
Gram negative cocci
Maltose fermenter - N meningitidis. Maltose nonfermenter - N gonorrhoeae
Gram negative coccoid rods
H flu, pasteurella, brucella, bordatella pertussis
Gram negative comma shaped (oxidase positive)
Grows at 42 C - campylobacter jejuni. Grows in alkaline media - vibriocholerae
Gram negative lactose fermenting rods
Fast fermenters - klebsiella, e coli, enterobacter. Slow fermenters - citrobacter, serratia, others
Gram negative non lactose fermenting rods
Oxidase negative - shigella (no H2S production), salmonella and proteus (H2S production). Oxidase positive - pseudomonas
Why dont you get lasting imunity from gonoccocal infection?
Due to rapid antigenic variation of pilus proteins (which is also why we dont have a vaccine)
What does meningococcus cause?
Meningococcemia, meningitis, and Waterhouse-Friderichsen syndrome
What does gonococcus cause?
Gonorrhea, septic arthritis, neonatal conjuctivitis, PID, and Fitz-Hugh-Curtis syndrome
What does meningococcus have that is analogous to LPS of enteric gram negatives?
LOS
Prophylaxis of meningococcus close contacts
Rifampin
Treatment of gonococcus and meningococcus respectively
Gonococcus - cetriaxone, meningococcus - ceftriaxone or penicillin G
What does h flu cause?
Epiglottitis (cherry red), Meningitis, Otitis media, and Pneumonia
Transmission of h flu
Aerosol
Treatment and prophylaxis for h flu
Ceftriaxone (treatment) and rifampin (close contact prophylaxis)
What is contained in the HiB vaccine?
PRP component of the HiB capsule conjugated to diphtheria toxoid (give between 2 and 18 months of age)
Test of choice for legionella
Urine assay for antigen
Transmission and habitat of legionella
Aerosol. Water source habitat
Treatment for legionella
Erythromycin
What presentation in a pneumonia case would suggest legionella over strep pneumo?
Pneumonia + GI + Neuro symptoms
High fever in smoker with diarrhea, confusion, cough, and chest pain
Legionella
Erythema gangrenosum
Necrotic skin condition due to pseudomonas exotoxin
What is pseudomonas associated with
Wound and burn infection, pneumonia (esp in CF), sepsis (black lesions on skin), swimmers ear, UTI, drug users and diabetic osteomyelitis, hot tub folliculitis, malignant otitis externa in diabetics
Smell of pseudomonas
Grape like odor
Treatment for pseudomonas
Aminoglycoside plus extended-spectrum penicillin (piperacillin, ticarcillin)
Most important virulence factor in e coli UTI
Fimbriae
E coli diarrhea in children
EPEC
Which e coli does not ferment sorbitol?
EHEC
Red currant jelly sputum
Klebsiella
Contrast DIC with TTP-HUS
1) Pts bleed in DIC. 2) Only platelets activated in TTP-HUS. 3) PTT and PT prolonged in DIC, 4) Low fibrinogen and increased FDP in DIC
Which populations are more common in TTP and HUS respectively
TTP - pts with mainly CNS symptoms. HUS - children with renal failure and mild CNS symptoms
Main differences betweeon salmonella and shigella
Salmonella have flagella and can disseminate hematogenously and produce H2S
What may prolong symptoms in salmonella infection?
Antibiotics
Rose spots on abdomen, fever, headache, diarrhea.
Salmonella typhi (typhoid fever). May remain in gallbladder in carrier state
How do shigella enter our cells?
They first enter antigen sample M (microfold) cells, then spread to epithelial cells
How do Shigella move?
Actin polymerization (they do not have flagella like salmonella do)
Most common cause of bloody diarrhea
Campylobacter jejuni. This is especially true in children
Transmission of campylobacter
Fecal-oral through poultry, meat, unpasturized milk
Common antecedent to Guillain-Barre
Pet feces (puppies), contaminated milk, or pork
Diarrhea outbreaks in day care centers. Can also cause mesenteric adenitis which can mimic Crohns or appendicits
Yersinia entercolitica
Spirochetes
Borrelia, Leptospira, Treponema
Flulike symptoms, jaundice, photophobia with conjunctivitis.
Leptospirosis. Found in water contaminated with animal urine, prevalent among surfers and in the tropics
Severe jaundice and azotemia, fever, hemorrhage, anemia
Weils disease (icterohemorrhagic leptospirosis) - liver and kidney dysfuntcion from severe leptospira infection
Stages of lyme disease
1 - erythema migrans, flulike symptoms. 2 - Bells palsy, AV nodal block. 3 - chronic monoarthritis and migratory polyarthritis
Treatment for lyme
Doxycycline, ceftriaxone
Stages of syphilis
1 - painless chancre, 2 - rash, condylomata lata. 3 - Gummas, aoritis, neurosyphilis, argyll-robertson pupil
Saber shins, saddle nose, CN 8 deafness, Hutchinsons teeth, mulberry molars
Congenital syphilis
Argyll-Robertson pupil
Reactive to accomodation but not light
Causes of VDRL false positives
VDRL. Viruses (mono, hepatitis), Drugs, Rheumatic fever, Lupus and leprosy
Histologic appearance of brucellosis and what is the source?
Chronic caseating granulomas similar to Tb endocarditis. Unpasteurized dairy (common in cattle ranchers)
Source and organism of Q fever
Coxiella burnetii. Spores from tick feces and cattle placenta
Source and organism of ehrlichiosis
Ehrlichiosis chaffeensis. Lone star tick
Vector for francisella tularensis
Ticks, rabbits, deer fly
Vector for pasteurella multocida
Animal bite, cats, dogs
Organism and vector for epidemic typhys
Rickettsia prowazekii. Louse
Vector and organism for endemic typhyus
Rickettsia typhi. Flease
Characteristic finding in garnderella vaginalis infection
Fishy odor on addition of kOH
What infection is associated with sexual activity but is not an STD?
Garnerella overgrowth
Clue cells
Gardnerella overgrowth. Vaginal epithelial cells covered with bacteria
Treatment for gardnerella
Metronidazole
Where do Rickettsia live and what do they need to survive?
Intracellularly. Need CoA and NAD+
Rash starting centrally and spreading out sparing palms and soles
Epidemic typhys. R prowazekii carried by human body louse
Headache, fever, rash (vasculitis) starting on palms and soles
Rickettsia (but not typhus type. Typhus rash starts on trunk and spreads out)
Rickettsial pneumonia with no rash, no vector, and negative Weil-Felix
Q fever (coxiella burnetti). Organism can survive outside for a long time
Weil-Felix
Mixing pts serum with proteus antigens and antirickettsial antibodies will cross react with Proteus O antigen and agglutinate (if they have had a rickettsial infection)
Rash on palms and soles migrating to wrist, ankles, then trunk, headache, fever
Rocky mountain spotted fever
In what infections is palm and sole rash seen?
Coxsackie A (hand foot and mouth), RMSF, Syphilis
Two main forms in chlamydia life cycle
Elementary body (infectious), and Reticulate body
Lab diagnois of chlamydiae
Cytoplasmic inclusions on Giemsa or floresecent antibody stained smear
Chlamydia trachomatis serotypes
ABC - blindness, africa, chronic. D-K - urethritis, PID, ectopic, neonatal pneumonia and conjunctivitis. L1L2L3 - Lymphogranuloma venerum
Cause of atypical pnuemonia, high titer of cold aggultinins (IgM), grown on Eatons agar
Mycoplasma pneumoniae
Treatment for mycoplasma pneumoniae
Tetracycline or erythromycin (do not use penicillins as they have no cell wall)
Atypical pneumonia outbreak in military recruits or prisons
Mycoplasma pneumoniae
Main fungus in New England and mid-atlantic
Blastomyces
Main fungus in midwest
Histoplasma
Main fungus in southwest
Coccidiodes
Main fungus in latin america
Paracoccidiodes
Symptoms of histoplasmosis
pneumonia
Dimorphic fungus in bird or bat droppings
Histoplasmosis
Treatment for systemic mycoses
Fluconazole or ketoconazole (local), amphotericin B (systemic)
Dimorphic broad based buds
Blastomyces
Symptoms of blastomycosis
Inflammatory lung disease, can disseminate to skin and bone. Granulomatous nodules
Symptoms of coccidiodomycosis
Pneumonia and meningitis, can disseminate to bone and skin
Dimorphic fungus which looks like a ball of grapes
Coccidiodes
Which systemic mycoses can become a spherule filled with endospores (much larger than an RBC)?
Coccidiodes
Dimorphic fungus with captains wheel appearance
Paracoccidiodes
How does malassezia furfur affect skin pigment?
Degrades lipids, which produces acids that damage melanocytes and cause hypopigmentation or hyperpigmented patches
What kind of weather is conducive to malassezia furfur?
Hot, humid weather
Treatment for tinea versicolor
Topical miconazole, selenium sulfide
Histologic appearance of malassezia furfur
Spaghetti and meatball look on KOH prep
What cells are responsible for preventing candidiasis?
Th cells suppress superficial candidiasis. Neutrophils prevent hematogenous spread
Forms of candida
Dimorphic. Psuedohyphae and budding at 20C, Germ tubes at 37C
Treatment for candidiasis
Topical azole (vaginal), fluconazole or caspofungin (oral/esophageal), amphotericin B, fluconazole, caspofungin (systemic)
Acute angle hyphae
Aspergillus
How do aflatoxins cause cancer?
They cause a GC to TA mutation in p53
Which opportunistic fungal infections are not dimorphic?
Aspergillus, cryptococcus, mucor and rhizopus (I think), PCP (I think)
Histologic appearance of cryptococcus
Heavily encapsulated yeast. Little balls with smaller balls in them
How is cryptococcus acquired?
Inhalation (which results in hematogenous dissemination) from yeast in soil and pigeon droppings
Characteristic brain lesion from cryptococcus
Soap bubble lesions
What patients tend to get mucor and rhizpus infections?
DKA pts and leukemia pts
Headache, facial pain, black necrotic eschar on face, possible cranial nerve involvement
Mucor and rhizopus infections
How is PCP acquired?
Inhalation of yeast
Treatment for PCP
TMP-SMX, pentamidine, dapsone. Prophylax at CD4 less than 200
Dimorphic, cigar-shaped budding yeast that lives on vegetation
Sporothrix schenkii
Treatment for sporothrix schenkii
Itraconazole or KI
Bloating, flatulence, foul-smelling fatty diarrhea in campers and hikers
Giardiasis
How are giardia, entamoeba, and cryptosporidum respectively transmitted?
All are cysts in water
Treatment for giardia
Metronidazole
Treatment for entamoeba histolytica
Metronidazole and iodoquinol
Treatment for cryptosporidium
Prevention (water treatment), nitazoxanide
Bloody diarrhea, liver abscess, RUQ pain, flask-shaped colonic ulcers
Entamoeba
Chorioretinitis, hydrocephalus, intracranial calcifications
Toxoplasmosis (usually in HIV)
Transmission of toxoplasma
Cysts in meat or cat feces
Treatment for toxoplasma
Sulfadiazine and pyrimethamine
Rapidly fatal meningoencephalitis in someone who swam in a fresh water pool
Naegleria fowleri
Where do you look for the amoeba in naegleria infection?
CSF
Organism and vector for sleeping sickness
Trypanosoma brucei, gambiense, rhodesiense. Tsetse fly (painful bite)
Treatment for sleeping sickness
Suramin (blood-borne), melarsoprol (CNS protection)
Cycle length of the various malarias
Vivax/Ovale - 48 hours, Falciparum - irregular, Malariae - 72 hours
Which malaria has a dormant form in the liver?
Vivax-ovale
Which malaria causes cerebral malaria and how?
Falciparum. Parasitized RBCs occlude capillaries in brain (also kidney and lungs)
Malaria treatment
Start with chloroquine (blocks plasmodium heme polymerase). If resistant, use mefloquine. Vivax/ovale - add primaquine for hypnozoites
Fever and hemolytic anemia, northeastern United States, asplenia in severe disease
Babesia
Treatment for babesia
Quinine, clindamycin
Organism and vector in Chagas disease
Trypanosoma cruzi. Reduviid bug (kissing bug, painless bite)
Treatment for Chagas disease
Nifurtimox
Dilated cardiomyopathy, megacolon, megaesophagus
Chagas disease (mostly in S america)
Spiking fevers, hepatosplenomegaly, pancytopenia
Visceral leishmaniasis
Organism and vector of leishmaniasis
Leishmania donovani. Sandfly
Treatment for leishmaniasis
Sodium stibogluconate
Treatment for trichomonas vaginalis
Metronidazole (for patient and partner)
Organism and treatment for pinworm
Enterobius vermicularis. Bendazoles or pyrantel pamoate
Transmission of pinworm
Food contaminated with eggs
Nematode that encysts in muscle, causes periorbital edema
Trichinella spiralis
Nematode that penetrates the skin, causes vomiting, diarrhea, anemia
Strongyloides stercoralis
Nematode that penetrates skin of feet, causes anemia
Ancylostoma duodenale and Necator americans (hookworms)
Transmission and treatment of dracunculus medinensis
Drinking water, niridazole
Loa Loa
Transmitted by deer flies, causing skin swelling. Treat with DEC
Wuchereria bancrofti
Transmitted by female mosquito. Causes elephantiasis. Treat with DEC
Toxocara canis
Food contaminated with eggs, causes granulomas (can cause blindness) and visceral larva migrans. Treat with DEC
Treatment for taenia solium
Praziquantel (use bendazoles for neurocysticercosis)
Appearance of t solium lesions in the brain
Swiss cheese appearance
Treatment for diphyllobothrium latum
Praziquantel
Cysts in the liver that can cause anaphylaxis if antigens are released during removal
Echinococcus granulosus. Acquired from eggs in dog feces. Treat with bendazoles
Treatment for trematodes (flukes)
Praziquantel
Trematodes (flukes) (3)
Schistosoma, clonorchis sinesis (pigmented gallstones, cholangiocarcinoma), paragonimus westermani (crab meat, hemoptysis)
Routes of nematode infection and the worms that use each (6 total)
Ingestion - Enterobius, Ascaris, Trichinella. Cutaneous - Strongyloides, Ancylostoma, Necator
Parasite of brain cysts and seizures
T solium
Parasite of liver cysts
Echinococcus granulosus
Parasite of B12 deficiency
Diphyllobothrium latum
Parasite of biliary tract disease, cholangiocarcinoma
Clonorchis sinesis
Parasite of hemotypsis
Paragonimus westermani
Parasite of portal hypertension
Schistosoma mansoni
Parasite of hematuria, bladder cancer
Schistosoma haematobium
Parasite of microcytic anemia
Ancylostoma, necator
Complementation and the requirement for it
When one virus uses another viruses protein product. Both viruses have to be infecting the same cell at the same time
Phenotypic mixing
Coating of a progeny virus of virus A with surface proteins of virus B. Have to be infecting the same cell at the same time. Surface protein determines infectivity, but progeny carry virus A genetic material
Live attenuated vaccines (5)
Lead to longer production of mucosal IgA than killed vaccines. Smallpox, yellow fever, chickenpox, Sabins polio, MMR
Killed vaccines (4)
Rabies, influenza, salk polio, HAV
Recombinant vaccines (2)
HBV, HPV
All DNA viruses are what and what is the exception?
Double stranded, except the parvoviruses
What are all RNA viruses and what is the exception?
Single stranded except Reoviruses
RNA viruses
I went to a RETRO (retrovirus) TOGA (togavirus) party where I drank FLAVored (flavivirus) CORONA (coronavirus) and ate HIPPY (hepevirus) CALIfornia (Calcivirus) PICKLES (picornavirus)
What naked viruses are infectious?
dsDNA (except pox and HBV) and +strand ssRNA
Where do viruses replicate
DNA viruses - nucleus (except pox). RNA - cytoplasm (except influenza and retroviruses)
Naked viruses (7)
Calcivirus, Picornavirus, Reovirus, Parvovirus, Adenovirus, Papilloma, Polyoma
Which viruses acquire their envelops from nuclear membrane?
Herpesviruses (other get them from the PM)
DNA viruses (7)
Hepadna, Herpes, Adenoa, Pox, Parvo, Papilloma, Polyoma
All DNA viruses are icosehedral except which?
Pox (complex)
HHV-6
Roseola (exanthem subitum)
Which hepatitis virus is a DNA virus?
Hep B (it is a hepadnavirus)
What virus is not a retrovirus but has reverse transcriptase?
HBV
Most common viral cause of acute cystitis (dysuria, hematuria) in kids
Adenovirus
Febrile pharyngitis, sore throat, acute hemorrhagic cystitis, pneumonia, conjunctivitis
Adenovirus
Erythema infectiosum (fifth disease)
Parvo B19. Slapped cheek rash, hydrops fetalis in utero, RBC aplasia and RA-like symptoms in adults
Causes of pure red cell aplasia
Parvo B19 and thymoma
Histology of VZV infection
Intranuclear inclusions, multinucleate giant cells
Tzanck test
Smear to detect HSV-1, HSV-2 and VZV
Fever, hepatosplenomegaly, pharyngitis, lymphadenopathy (especially posterior cervical nodes). 15-20 years of age
Mononucleosis
Family and symptomology of norwalk virus
Calcivirus. Viral gastroenteritis
Which Hepatitis viruses are RNA viruses and what is the family of each?
HAV - Picorna, HCV - Flavi, HDV - Delta, HEV - Hepe
Picornaviruses (5)
Polio, Echo (aseptic meningitis), Rhino, Coxsackie (aseptic meningitis, herpangina, febrile pharyngitis, hand foot mouth disease), HAV
Paramyxoviruses (4)
Parinfluenza (croup), RSV (briochilitis in babies, treat with ribavirin), Rubeola (Measles), Mumps
Negative stranded RNA viruses (6)
Always Bring Polymerase Or Fail Replication. Arenaviruses, Bunyaviruses, Paramyxoviruses, Orthomyxoviruses, Filoviruses, Rhabdoviruses
Segmented viruses (4)
BOAR. All are RNA viruses. Bunyaviruses, Orthomyxoviruses, Arenaviruses, Reoviruses
Protein synthesis in picornaviruses
RNA translated into 1 large polypeptide that is cleaved by proteases into functional viral proteins
Spread of picornaviruses
Fecal oral (except rhinovirus)
Why doesnt rhinovirus affect the GI tract?
It is acid labile
High fever, black vomitus, jaundice
Yellow fever (a flavivirus)
Diarrhea in day care centers due to villous destruction with atrophy. A segmented RNA virus.
Rotavirus (a reovirus)
Fever, postauricular adenopathy, lymphadenopathy, arthralgias, fine truncal rash that starts at head and moves down.
Rubella (a togavirus, also called german measles). Mild in children but serious if congenital
What do paramyxoviruses have, what does it do, and how does this relate to treatment?
F (fusion) protein. Causes respiratory epithelial cells to fuse and form multinucleated cells. Palivizumab is a monoclonal antibody against F protein
Palivizumab
Monoclonal antibody against F protein (paramyxoviruses). Prevents pneumonia in premature infants
Descending maculopapular rash including hands and feet, koplik spots.
Measles (rubeola, a paramyxovirus)
Difference between the rashes in rubella and rubeola
Rubeola (measles) rash includes hands and feet. Rubella (german measles) rash stays on trunk. Both spread down from head
Potential sequelae of measles (rubeola)
SSPE (many years later), encephalitis, giant cell pneumonia (typically only in immunosuppressed)
Cough, cold like symptoms, conjunctivitis
Measles
Parotitis, aseptic meningitis, orchitis
Mumps (a paramyxovirus)
Between measles (rubeola) and german measles (rubella), which contains hemagglutinin?
Measles (rubeola), as it is a paramyxovirus
Fever, malaise, agitation, photophobia, hydrophobia, paralysis, coma, death
Rabies (progresses in that order)
Histology of hepatitis A infection
Hepatocyte ballooning degeneration and apoptosis
Histology of Hep B infection
Fine, eosinophilic, cytoplasmic granules of HBsAg are visible, giving ground glass appearance
Transmission of HBV
Parenteral, sexual, maternal-fetal
Symptoms of HBV prodromal period
Serum-sickness like
What viral hepatitises predispose to cancer and which cancer?
HCC. HBV and HCV
Best test for active HAV infection
Anti-HAVAb (IgM)
Best test for prior HAV infection
Anti-HAVAb (IgG). Can also indicate prior vaccination
What Hep B serologic marker indicates high transmissibility?
HBeAg
HIV structural genes
Env (gp120 for attachment, gp41 for fusion and entry), Gag (p24 capsid), Pol (reverse transcriptase)
What receptors does HIV use for entry?
CXCR4 or CCR5 (CD4 cells), CCR5 and CD4 (macrophages)
Why are HIV tests initially falsely positive in babies born to infected mothers?
Anti-GP120 crosses placenta
Where does the HIV virus replicate during the latent phase?
Lymph nodes
What fungal infection is commonly picked up by spelunkers?
Histoplasma capsulatum (from bats)
Low-grade fever, cough, hepatosplenomegaly, tongue ulcer, only pulmonary symptoms if CD4 count greater than 100
Histoplasma
Encephalopathy and demyelination in pt with CD4 count below 200
JC virus reactivation
Ring-enhancing brain abscesses with CD4 count below 100
Toxoplasma
CD4 count for cryptococcus meningitis
Below 50
CD4 count for CMV retinitis
Below 50. Will see cotton-wool spots
CD4 ranges for PCP and MAI infections respectively
PCP - below 200, MAI - below 50
Bugs that can mimic appendicits (3)
Yersinia enterocolitica, campylobacter jejuni, non-typhoidal salmonella. Mimic appendicits by causing mesenteric adenitis
Bugs causing bloody diarrhea (7)
Campylobacter, salmonella, shigella, EHEC, EIEC, Yersinia enterocolitica, Entamoeba histolytica
Bugs causing watery diarrhea (4)
ETEC, Vibrio choleraea, C diff, C perfringens. Also protozoa - giardia, cryptosporidium, viruses - rota, adeno, norwalk
Most common causes of pneumonia (in order with most common first) in neonates
Group B strep, E coli
Most common causes of pneumonia (in order with most common first) in children 4 weeks to 18 years
Viruses (RSV), Mycoplasma, Chlamydia trachomatis, Strep pneumo
Most common causes of pneumonia (in order with most common first) in adults (18-40)
Mycoplasma, C pneumoniae, Strep pneumo
Most common causes of pneumonia (in order with most common first) in adults (40-65)
Strep pneumo, H flu, Anaerobes, Viruses, Mycoplasma
Most common causes of pneumonia (in order with most common first) in elderly
Strep pneumo, Influenza, Anaerobes, H flu, Gram negative rods
Most common causes of nosocomial pneumonia
Staph, enteric gram negative rods
Most common causes of aspiration pneumonia and treatment
Anaerobes. Clindamycin
Most common causes of pneumonia in alcoholics and IV drug users
Strep pneumo, Klebsiella, Staph
Most common causes of pneumonia in CF
Pseudomonas
Most common causes of atypical pneumonia
Mycoplasma, Legionella, Chlamydia
CSF findings in bacterial meningitis
WBC high (over 1000) predominantely neutrophils. Glucose low (below 70), protein high
Most common causes of meningitis (in order with most common first) in newborn
Group B strep, E Coli, Listeria
Most common causes of meningitis (in order with most common first) in children (6 mos to 6 years)
Strep pneumo, N meningitidis, HiB, Enteroviruses
Most common causes of meningitis (in order with most common first) in 6 to 60 years
Strep pneumo, N meningitidis (number 1 in teens), Enteroviruses, HSV
Most common causes of meningitis (in order with most common first) in elderly
Strep pneumo, GNRs, Listeria
Enteroviruses
Coxsackie, Echo, Polio, others
CSF findings in viral meningitis
WBC below 500 predominantely lymphocytes, glucose normal or near normal, protein elevated but below 70
Treatment of meningitis
Cetriaxone and vanco empirically. Add ampicillin if Listeria suspected
Fever, headache, photophobia, nuchal rigidity, painful extraocular movements
Meningitis
CSF findings in fungal/Tb meningitis
Very similar to bacterial except WBC predominance is lymphocytes instead of PMNs
Fever with positive gallium scan
Osteomyelitis
Most common causes of osteomyelitis in: all comers, sexually active, DM and IVDU, sickle cell, prosthetics, vertebral, animal bite
All - S aureus, Sexually active - N gonorrhoeae (rare), DM and IVDU - pseudomonas, Sickle - Salmonella, Prosthetics - S aureus and s epidermis, Vertebral - M Tb (potts disease), Animal bite - Pasteurella
Where in the bone does osteomyelitis typically occur
Metaphysis of long bones
Features seen in pyelonephritis but not cystitis
Fever, chills, flank (vs suprapubic) pain, CVA tenderness, hematuria, WBC casts (vs WBCs)
Predisposing factors to UTI
Female, obstruction, kidney surgery, catheterization, GU malformation, DM, pregnancy
Markers for UTI agents
Positive leukocyte esterase test - bacterial UTI, Positive nitrite test - gram negative bacterial UTI
Urease producing bugs that cause UTIs
Proteus, Klebsiella. Negative urease test suggests E coli, Strep, Enterococcus
ToRCHHeS
Toxoplasma, Rubella, CMV, HIV, HSV-2, Syphilis
Hepatosplenomegaly, jaundice, thrombocytopenia, growth retardation in newborn
Common features of ToRCHHeS infections
Which TORCHES infection often includes poor feeding?
Toxoplasma
Maternal symptoms for each of the ToRCHHeS infections
Toxo - asymptomatic or lymphadenopathy. Rubella - Rash, postauricular lymphadenopathy, polyarthritis. CMV - Asymptomatic or mono-like. HIV - variable. HSV-2 - Asymptomatic or herpetic lesions. Syphilis - Chancre, rash, or cardiac/neuro disease
PDA, cataracts, deafness, blueberry muffin rash (may or may not be present)
Congenital rubella
Hearing loss, seizures, petechial rash, blueberry muffin rash
Congenital CMV
Recurrent infections, chronic diarrhea in newborn
Congenital HIV
Temporal encephalitis, herpetic lesions in newborn
Congenital HSV-2
Stillbirth or facial abnormalities, saber shins, and CN 8 deafness
Congenital syphillis
Slapped cheek rash
Parvo B19
Vesicular rash on palms and soles. Ulcers in oral mucosa
Coxsackie Type A (hand-foot-mouth disease)
Urethritis, cervicitis, PID, prostatitis, epididymitis, arthritis, creamy purulent discharge
Gonorrhea
Painful genital ulcer, inguinal adenopathy
Chancroid (haemophilus ducreyi)
Painful penile, vulvar, or cervical vesicles and ulcers. With or without fever, headache, myalgia
HSV-2
Noninflammatory, malodorous discharge, positive whiff test, clue cells
Gardnerella vaginosis
Two most common causes of PID
Chlamydia trachomatis and N gonorrhoeae
Cervical motion tenderness, purulent cervical discharge
PID. May progress to salpingitis, endometritis, hydrosalpinx, and tubo-ovarian abscess
Fitz-Hugh-Curtis
Infection of the liver capsule and violin string adhesions of parietal peritoneum to liver. Caused by ascending PID (esp N gonorrhoeae)
Causes of meningitis in unimmunized children
HiB and polio
What bug should you associate with sulfur granules?
Actinomyces israelii
Action of penicillin and its dervitives
Block cell wall synthesis by inhibition of peptidoglycan cross linking
Drugs that block peptidoglycan synthesis
Bacitracin, vancomycin
Drugs that block nucleotide synthesis
Sulfonamides, trimethoprim
Drugs that block DNA topoisomerases
Fluoroquinolones
Drugs that block mRNA synthesis
Rifampin
How does metronidazole work?
Damages DNA
Dicloxacillin
A penicillin derivative related to methicillin and nafcillin
Which has greater oral bioavailability, amoxicillin or ampicillin?
Amoxicillin
Main uses of ampicillin and amoxicillin
H flu, E coli, Listeria, Proteus, Salmonella, Shigella, enterococci
Most important use of ticarcillin, carbenicillin, and piperacillin
Pseudomonas. Also covers GNRs
Clavulanic Acid, Sulbactam, Tazobactam
B-lactamase inhibitors
What do cephalosporins block?
Transpeptidases (also called penicillin binding proteins)
Organisms not covered by cephalosporins are LAME
Listeria, Atypicals (chlamydia, mycoplasma), MRSA, Enterococci
Toxicities of cephalosporins
Hypersensitivity reactions, Vitamin K deficiency, Disulfiram-like reaction
Aztreonam
Monobactam resistant to B-lactamases. Binds PBP3, no cross-allergenicity with penicillins. GNR coverage only.
Main use of aztreonam
Penicillin-allergic pts and those with renal insufficiency who cannot tolerate aminoglycosides
Imipenem/cilastatin and meropenem
Limited by side effects, use in life-threatening infections after other options exhausted.
Cilastatin
Inhibits renal dehydropeptidase to decrease inactivation of imipenem
What are penicillins structural analogs of in bacteria?
The D-Ala-D-Ala sequence (which vancomycin binds)
Toxicities of vancomycin
Nephrotoxicity, Ototoxicity, Thrombophlebitis, red man syndrome
What causes vancomycin resistance?
Change of D-ala-D-ala to D-ala-D-lac
Protein synthesis inhibitor targets
buy AT 30, CCEL at 50. 30S - Aminoglycosides, Tetracyclines. 50S - Chloramphenicol, Clindamycin, Erythromycin (macrolides), Linezolid
Aminoglycosides (5)
Gentamicin, Neomycin, Amikacin, Tobramycin, Streptomycin
Action of aminoglycosides
Inhibit formation of initiation complex and cause misreading of mRNA (bactericidal)
What type of bacteria are aminoglycosides ineffective against and why?
Anaerobes, because they require O2 for uptake
Main use of aminoglycosides
Severe GNR infections
Toxicities of aminoglycosides
Nephrotoxicity, Ototoxicity, Teratogenic
Resistance of aminoglycosides
Transferase enzymes inactivate drug by acetylation, phosphorylation, or adenylation
Tetracyclines (4)
Tetracycline, doxycycline, demeclocycline, minocycline
Which tetracycline is used in a renal disorder and which disorder?
Demeclocycline (ADH antagonist) is used in SIADH
Action of tetracyclines
Bind 30S, prevent aminoacyl-tRNA attachment
Instructions for patients taking tetracyclines
Do not take with milk, antacids, or iron-containing preparations as these will inhibit tetracycline absorption
What makes tetracyclines so effective against Rickettsia and Chlamydia
They accumulate intracellularly
Action of macrolides
Bind 50S (23S rRNA subsubunit) and prevent translocation
Main uses of macrolides
Atypical pneumonias, URIs, STDs, gram positive cocci, Neisseria
Toxicities of macrolides
Prolonged QT, GI discomfort (most common cause of noncompliance), acute cholestatic hepatitis, eosinophilia, skin rashes
What drugs are increased in plasma concentration by macrolides?
Theophyllines and oral anticoagulants
Action of chloramphenicol
Binds 50S - blocks peptide bond formation
Resistance to chloramphenicol
Plasmid-encoded acetyltransferase inactivates drug
Action of clindamycin
Binds 50S - blocks peptide bond formation
Main uses of clindamycin
Anaerobic infections in aspiration pneumonia or lung abscesses
General principle for treating anaerobes
Above the diaphragm - clindamycin, Below the diaphragm - metronidazole
Sulfonamides (3)
Sulfamethoxazole (SMX), sulfisoxazole, sulfadiazine
Action of sulfonamides
Inhibit dihydropteroate synthase (needed for DNA synthesis). Are PABA antimetabolites
Fluoroquinolones (9)
Ciprofloxacin, norfloxacin, levofloxacin, ofloxacin, sparfloxacin, moxifloxacin, gatifloxacin, enoxacin, nalidixic acid (a quinolone)
Uses for metronidazole
Giardia, Entamoeba, Trichomonas, Gardnerella, Anaerobes.
Toxicities of metronidazole
Disulfiram-like reaction, headache, metallic taste
Prophylaxis for Tb, MAI, and M leprae respectively
Tb - INH, MAI - Azithromycin, M leprae - None
What is responsible for acid fastness?
Mycolic acids
What is needed to activate INH?
Bacterial catalase-peroxidase (KatG)
Toxicities of INH
Neurotoxic, hepatotoxic, lupus. Pyridoxine (B6) can prevent neurotoxicity and lupus
What causes different INH half life in different individuals
Fast vs slow acetylators
4 Rs of Rifampin
RNA polymerase inhibitor, Revs up P-450, Red/orange body fluids, Rapid resistance if used alone
Pyrazinamide
Anti-tb. Inhibits mycolic acid production by blocking pyrazanamidase
Ethambutol
Anti-tb. Decreases carbohydrate polymerization of cell wall by blocking arabinosyltransferase. Can cause optic neuropathy (red-green color blindness)
Prophylaxis for each of the following: meningococcus, gonorrhea, syphilis, recurrent UTIs, endocarditis with surgical or dental procedures
Meningococcus - Cipro, rifampin or minocycline. Gonorrhea - Cetriaxone, Syphilis - Benzathine penicillin G, Recurrent UTI - Bactrim, Endocarditis - Penicillins
HIV prophylaxis at CD4 below: 200, 100, and 50
200 - Bactrim (PCP), 100 - Bactrim (PCP and Toxo), 50 - Above and Azithryomycin (MAI)
Treatment for VRE
Linezolid and quinupristin/dalfopristin
Empiric therapy for community-acquired pneumonias
Outpatient - macrolides, Inpatient - fluoroquinolones, ICU - B-lactam + (fluoroquinolone or azithromycin)
What antifungals affect each of the following: membrane function, cell wall synthesis, ergosterol synthesis, lanosterol synthesis, nucleic acid synthesis
Membrane - Amphotericin B, Cell wall - Caspofungin, Ergosterol - fluconazole, itraconazole, voriconazole, terbinafine, Lanosterol - naftitine, Nucleic Acids - 5-fluorocytosine
Action of amphotericin B
Binds ergosterol and forms pore that allow leakage of electrolytes
What do you have to supplement in amphotericin treatment and why?
K and Mg because of altered renal tubule permeability
Action and delivery of nystatin
Same as amphotericin (binds ergosterol and makes pores). Topical only because too topic systemically
Action of caspofungin
Inhibits cell wall synthesis by inhibiting synthesis of B-glucan
Action of terbinafine
Inhibits fungal enzyme squalene epoxidase (necessary for ergosterol synthesis)
Action of griseofulvin
Inhibits MT function, disrupting mitosis
Antiprotozoals (5)
Pyrimethamine (toxo and falciparum), suramin and melarsoprol (sleeping sickness), nifurtimox (Chagas), Sodium stibogluconate (leishmaniasis)
Action of chloroquine
Blocks plasmodium heme polymerase
Antihelminthic drugs
Mebendazole, pyrantel pamoate, ivermectin, DEC, praziquantel. They all immobilize helminths
Amantadine
Blocks viral penetration and uncoating (M2 protein). Causes release of dopamine from nerve terminals
Use and toxicity for amantadine
Influenza A, Parkinsons disease. Causes ataxia, dizziness, slurred speech. 90 pct of influenza A resistant to amantadine
Zanamivir and oseltamivir
Inhibit neuraminidase, decreasing release of progeny viruses. Use in both Influenza A and B
Ribavirin
Inhibits synthesis of guanine nucleotides by competitively inhibiting IMP dehydrogenase. Use in RSV and Hep C. Can cause hemolytic anemia, is teratogenic
Activation and Action of Acyclovir
Monophosphorylated by HSV/VZV thymidine kinase. Guanosine analog
Uses of acyclovir
HSV, VZV, EBV. Use famciclovir for herpes zoster
Toxicities of acyclovir
Can cause crystalline nephropathy if adequate hydration not provided
Uses of ganciclovir
CMV
Toxicities of gancicyclovir
Leukopenia, neutropenia, thrombocytopenia, renal toxicity. Much more toxic than acyclovir
Foscarnet
Viral DNA pol inhibitor (binds pyrophosphate-binding site, no activatoin required).
What effect does foscarnet have on electrolyte levels
Can chelate Ca and promote Mg wasting (leads to low Ca and Mg levels)
Cidofovir
Inhibits viral DNA pol. Does not require phosphorylation. Nephrotoxic (give with probenecid)
HAART regimens
2 NRTIs with 1 NNRTIs or 1 PI or 1 Integrase inhibitor
Lopinavir, atazanavir, darunavir, fosamprenavir, saquinavir, ritonavir, indinavir
Protease inhibitors
Toxicities of protease inhibitors
Hyperglycemia, GI intolerance, lipodystrophy (fat redistribution similar to Cushings)
NRTIs (7)
Tenofovir, Emtricitabine, Abacavir, Lamivudine, Zidovudine, Didanosine, Stavudine
Toxicities of NRTIs
Bone marrow suppression, peripheral neuropathy, lactic acidosis, rash, megaloblastic anemia
NNRTIs (3)
Nevirapine, Efavirenz, Delaviridine
Raltegravir
Integrase inhibitor. Inhibits HIV genome integration. Can cause hypercholesterolemia
Uses for each of the interferons
Alpha - Chronic Hep B and C, Kaposi sarcoma. Beta - MS. Gamma - NADPH oxidase deficiency
Toxicities of the interferons
Neutropenia
Antimicrobials to avoid in pregnancy
Countless SAFe Moms Take Really Good Care. Clarithromycin, Sulfonamides, Aminoglycosides, Fluoroquinolones, Metronidazole, Tetracyclines, Ribavirin, Griseofulvin, Chloramphenicol
What bacterium likes the gallbladder?
Salmonella typhi