Basic Bacteriology Flashcards
Don’t gram stain
Treponema, mycobacteria, mycoplasma, legionella (intracellular), rickettsia (intracellular), chlamydia (intracellular)
Giemsa stain
Chlamydia, borrelia, rickettsia, trypanosomes, plasmodium
PAS stain
Stains glycogen and mucopolysaccharides
Ziehl-Neelsen/ carbon fuchsin stain
Acid fast bacteria and Protozoa
India ink
Stains cryptococcus
Silver stain
Stains fungi, legionella, h pylori
Chocolate agar
Stains H. Flu
Thayer-Martin stain
Stains Neisseria
Bordet-Gengou/Regan-Lowe medium
Stains B. Pertussis
Eaton agar
Stains M. Pneumo
MacConkey agar
LF turn pink
EMB agar
Stains E. coli
Charcoal yeast extract
Stains legionella
Sabouraud agar
Stains fungi
Glycocalyx
Loose network of polysaccharides that mediates adherence to surfaces
Intracellular bugs
Obligate: Rickettsia, Chlamydia, Coxiella (need host ATP)
Facultative: Salmonella, Neisseria, Brucella, Mycobacterium, Listeria, Francisella, Legionella, Yersinia pestis
Encapsulated bacteria
Strep pneumo, H. flu, Neisseria meningiditis, E Coli, Salmonella, Klebsiella, Groub B strep (capsules = anti-phagocytic; asplenics are at increased risk)
Urease-positive organisms
CHuck Norris hates PUNKSS:
Cryptococcus, H pylori, Proteus, Ureaplasma, Nocardia, Klebsiella, S. epidermidis, S. saprophyticus
Catalase positive organisms
Cats Need PLACESS to hide:
Nocardia, Pseudomonas, Listeria, Aspergillus, Candida, E. coli, Staph, Serratia
Chronic granulomatous disease (NADPH oxidase deficiency) have recurrent infections with these guys.
Pigment-producing bacteria
Actinomyces israelii (yellow granules), S. aureus (yellow), Pseudomonas (blue-green), Serratia marcescens (red)
Bacterial virulence factors
Protein A - S. aureus, binds Fc region of IgG to prevent opsonization/phagocytosis
IgA protease - S. pneumo, H. flu, Nesseria - cleaves IgA to help colonize respiratory mucosa
M protein - Group A strep, prevents phagocytosis and may –> rheumatic fever
Exotoxin location of genes
Plasmid or bacteriophage
Endotoxin location of genes
Bacterial chromosome
Bugs with exotoxins
Inhibit protein synthesis:
Corynebacterium diphtheriae, Pseudomonas aeruginosa (both inactivate elongation factor), Shigella and EHEC (Shiga and Shiga-like toxins, both increase cytokine –> HUS; Shiga also invades mucosa –> dysentery)
Increase fluid secretion:
ETEC (heat labile [increase cAMP] and heat-stable [increase cGMP] toxins –> watery diarrhea), Bacillus anthracis (edema toxin mimics AC), vibrio cholerae (overactivates AC by permanently activating Gs –> increased Cl- secretion in gut and rice-water diarrhea)
Inhibit phagocytic ability
B. pertussis (overactive AC by disabling Gi)
Inhibit release of neurotransmitter:
Clostridium - cleave SNARE (tetani prevents release of inhib NTs from Renshaw cells –> spasticity; botulinum inhibits ACh (stimulatory) –> flaccid paralysis
Lyse cell membranes: Clostridium (alpha toxin –> gas gangrene from degradation of phospholipids) and Streptococcus pyogenes (streptolysin O)
Superantigens –> shock (Staph aureus - TSST-1, Strep pyogenes - Exotoxin A) - via release of IL-1, IL-2, IFN-gamma, TNF-alpha
Role of endotoxin
LPS in G- –> activates macrophages, activates complement, activates tissue factor
Transformation
Bug can pick up naked DNA from environment
Conjugation
Bacterial sex (F+ plasmid contains genes for sex pilus and conjugation - meets up with F- and passes single strand plasmid DNA across conjugal bridge)
Can include some plasmid genes if F+ plasmid was incorporated into bacterial chromosome (Hfr)
Transposition
Segment of DNA that can jump from plasmid to chromosome and vice versa
Transduction
Phage infects bacterium and cleaves bacterial DNA (generalized - lytic phage) or incorporates its DNA into bacterial chromosome (lysogenic) and then when phage DNA is excised, takes some bacterial with it (“specialized transduction”)
Lysogenic phase bacterial toxins:
Shiga-like, Botulinum, Cholera, Diphtheria, S. pyogenes
G+ lab algorithm
G+ = purple/blue
Catalase positive cocci = Staph –> Coag positive = aureus; Coag negative –> Novobiocin (sensitive = epidermidis, resistant = saprophyticus)
Catalase negative cocci = Strep –> hemolysis (alpha [green on blood agar] = pneumo [capsule, optochin sens, bile soluble] and viridans; beta [clear on blood agar] = pyogenes [bac sensitive], and agalactiae [bac res]; gamma = Group D (Enterococcus) vs. S. bovis)
Strep pyogenes
Group A strep!
Pyogenic sx (pharyngitis, cellulitis, impetigo, erysipelas)
Toxigenic sx (scarlet fever, TSS, necrotizing fasciitis)
Immuno sx (RF, acute GN)
Bacitracin sensitive, beta hemolytic, PYR+, M protein = virulence factor and Ig to it enhance host defenses but can also –> RF
ASO titer
Detect recent Strep pyogenes infection
JONES criteria
Criteria for acute RF (usually preceded by pharyngitis)
Joints (polyarthritis) Heart (carditis) Nodules (subcut) Erythema marginatum Sydenham chorea
Strep viridans
Alpha hemolytic, optochin res, normal flora of oropharynx
Can –> dental caries and subacute bacterial endocarditis at already damaged heart valves
Strep pneumo
G+ diplococci, encapsulated, optochin sensitive, alpha hemolytic
Sx = MOPS
Staph aureus
Inflamm sx (skin infections, pneumo, endocarditis, osteomyelitis)
Toxin-mediated sx (TSST-1, scalded skin syndrome, rapid-onset food poisoning)
MRSA
Coag positive, Catalase positive
Staph epidermidis
Catalase positive, Coag negative, novobiocin sensitive
Infect prosthetic devices (biofilm)
Staph saprophyticus
Catalase positive, Coag negative, Novobiocin resistant
Uncomplicated UTI in young women
Strep agalactiae
Group B strep
Bacitracin resistant, beta-hem, babies!
Group D strep
Enterococcus - UTI, biliary tract infxn, subacute endocarditis; VRE!
Strep bovis - colonizes gut, can –> bacteremia and subacute endocarditis, assoc with colon cancer
Cystine-tellurite agar
Grows corynebacterium diphtheriae
corynebacterium diphtheriae
Makes exotoxin that inhibits protein synthesis –> pseudomem pharyngitis with LAD, myocarditis and arrhythmias
Toxoid vaccine
Spore forming bacteria
Bacillus
Clostridium
Coxiella
C diff toxins
Toxin A: enterotoxin, binds brush border of gut
Toxin B: cytotoxin –> cytoskeletal disruption via actin depolymerization –> pseudomem colitis
Detect toxins in stool to diagnose
Anthrax
Bacillus anthracis = G+, spore-forming rod
Cutaneous: painless papule surrounded by vesicles –> black eschar
Pulmonary: inhale spores –> flu-like sx –> fever, pulmonary hemorrhage, mediastinitis, shock
Bacillus cereus
Spores (esp in reheated rice) –> enterotoxin ingestion –> food poisoning
Actinomyces vs. Nocardia ([an]aerobe? stain? sx? tx?)
Actinomyces = anaerobe; Nocardia = aerobe
A = gram pos; N = gram pos and weakly acid fast
A -> oral/facial abscesses that drain through sinuses, yellow “sulfur granules”
N -> pulmonary infections or cutaneous infxns following trauma in IC pts
Sulfonamides for Nocardia, Penicillin for Actinomyces (SNAP)
AIDS prophylaxis regimens with CD4 counts
- M. avium: prophylaxis with azithromycin when CD4+ count less than 50
- PCP: TMP-SMX, dapsone, atovaquone when CD4 less than 200
- Toxo: TMP-SMX, CD4
Gram negative lab algorithm
Gram stain –> pink = G-
Diplococci? Neisseria meng = maltose fermenter; N. gonorrhoeae = maltose non-fermenter
Rod-cocci = Haemophilus, Pasteurella, Brucella, Bordetella
Rods –> LF (Klebsiella, E Coli, Enterobacter); NLF –> oxidase positive (pseudomonas) vs. oxidase negative (Salmonella, Proteus, Yersinia [all produce H2S], Shigella)
Cause of Waterhouse-Friedrichsen syndrome
Neisseria meningiditis (adrenal failure due to hemorrhage)
Meningitis treatment (N.meng or H. flu)
Ceftriaxone; rifampin for prophylaxis in close contacts
- Vaccine for HiB now routine; vaccine for N.meng exists but not routine
Symptoms of H. flu
Epiglottitis (cherry red), Meng, Otitis media, Pneumo
Treat mucosal infxns with amox +/- clavulanate
Pseudomonas symptoms/disease associations
Pneumo (can be chronic in CF) sepsis otitis externa UTIs Drug use Diabetes Osteomyelitis (esp with puncture wounds, burns)
Also, ecthyma gangrenosum (rapidly progressive, necrotic cutaneous lesion caused by pseudomonas bacteremia, especially in IC pts)
E coli virulence factors
Fimbriae - cystitis and pyelo
K capsule - PNA, neonatal meng
LPS endotoxin - septic shock
Types of E Coli
EIEC - invasive dysentery –> necrosis and inflam
ETEC - traveler’s diarrhea, no inflamm or invasion
EPEC - no toxin, adheres to apical surface and flattens villi –> no abs
EHEC/STEC - shiga-like toxin –> HUS (anemia, thrombocytopenia, renal failure due to microthrombi)
Klebsiella
Aspiration (DM and alcoholics) Lobar pneumo with currant jelly sputum
Campylobacter jejuni
Bloody diarrhea, esp in kids; fecal-oral transmission
Can –> guillan-barre and reactive arthritis
Typhoid fever
Caused by Salmonella typhi
Sx: rose spots on abdomen, constipation, ab pain, fever
Tx: ceftriaxone or fluoroquinolone
Oral vaccine = live/att; IM vaccine with capsular polysacch
Dysentery
Causes:
Campylobacter
Salmonella (not typhi) - makes H2S, found in poultry, eggs, pets
Shigella (makes shiga toxin, which is invasive, so low infectious dose, cell-to-cell (not hematogenous) spread)
Entamoeba histolytica (amebiasis - cysts in water, can also get liver abscess)
Vibrio cholerae mechanism of action
Enterotoxin permanently activates Gs –> increased cAMP –> watery diarrhea
Pseudoappendicitis
Caused by yersinia enterocolitica (right lower ab pain due to mesenteric adenitis or terminal ileitis)
Pet feces, contaminated milk
H. pylori diagnosis and treatment
Diagnosis: urea breath test (catalase, oxidase, and urease +) or fecal antigen test
Tx: PPI, clarithro, amoxicillin
Stages of syphilis
Primary - painless chancre
Secondary - disseminated disease, maculopapular rash (ON HANDS AND SOLES), condyloma lata
Tertiary - gummas, aortitis, Argyll Robertson pupil (accomodates but doesn’t react to light), neuro sx (general paresis/ataxia)
VDRL/RPR positive (nonspecific) –> confirm with FTA-Abs
Congenital syphilis sx and prevention
Snuffles, saddle nose, notched teeth, facial abnormalities (linear scars), mulberry molars, short maxilla, saber shins
Treat mom early in preg!
VDRL false positives
VDRL:
Viral infection
Drugs
RF
Lupus and leprosy
Jarisch-Herxheimer reaction
Flu-like syndrome after abx are started –> kill some bugs (usu spirochetes) that release endotoxin
Pasteurella multocida
Animal bite
Cellulitis, osteomyelitis
Rickettsia types and transmission
Prowazekii - epidemic typhus, louse
Rickettsii - RMSF, dermacentor (dog tick) - rash starts at wrists and ankles
Typhi - endemic typhus, fleas
typhus: rash starts on trunk
Clue cells
Vaginal epithelial cells covered with Gardnerella bacteria (“stippled”)
fishy smell to discharge, nonpainful
Rashes
Syphilis - hands and soles
R. rickettsii (RMSF) - wrists and ankles
R. typhi/prowazekii - central rash (spares palms and soles)
Coxsackie A (hand, foot, and mouth dz) - palms and soles
Measles - starts at head/neck and spreads downward; Koplik spots in mouth
Rubella - pink macules beginning at head and moving down –> desquamation
Roseola - rose-colored macules several days after fever
Parvo B19 - slapped cheek rash on face
VZV/Chickenpox - vesicular rash begins on trunk and spreads to extremities
Ehrlichiosis (dz + histo) vs. Anaplasmosis (dz + histo)
Ehrlichia, vector is tick
Histo: monocytes with morulae in cytoplasm
Anaplasma, vector is tick
Histo: granulocytes with morulae in cytoplasm
Chlamydia (types + tx)
Trachomatis - reactive arthritis (Reiter syndrome), follicular conjunctivitis, nongonococcal urethritis, PID
- Serotype A,B,C - chronic infxn in Africa (can –> blindness)
- Serotype D-K - urethritis/PID, ectopic preg, neonatal pna with eosinophilia, neonatal conjunctivitis
- Serotypes L1-3: lymphogranuloma venereum (small, painless ulcers on genitals –> swollen, painful ln)
Pneumo/psittaci - atypical PNA, aerosol transmission
Tx: Azithro
Atypical PNA
Mycoplasma pneumo
Chlamydia
Treat with doxy
Systemic mycoses
Histo (Mississipi, Ohio River) – pneumo, fills macrophages
Blasto (east of histo) –> inflamm lung dz, granulomatous nodules, ~size of RBC
Coccidioidomycosis - SW –> PNA a nd meng, spherules filled with endospores bigger than RBC
Paracoccidioidomycosis - Latin America - budding yeast looks like “captain’s wheel”
Opportunistic mycoses
- Candida albicans (thrush in IC, vulvovaginitis in DM or with abx, diaper rash, endocarditis in IVDU, chronic mucocut candidiasis)
- Aspergillus fumigatus (ABPA, aspergillomas, aflatoxins; dz esp in IC and those with chronic granulomatous disease), branch at acute angles
- Cryptococcus (meng, cryptococcosis) - in soil and pigeon droppings, stain with India Ink, see “soap bubble” lesions in brain
- Mucor/Rhizopus (mucormycosis, esp in ketoacidotic DM and/or neutropenic pts) - fungi grow in vv and penetrate crib plate
- Pneumocystis jirovecii –> PCP (diffuse interstitial PNA with ground glass appearance on CXR), esp in IC pts, diag by lavage or bx; stain with silver stain
- Sporothrix schenckii –> Sporotrichosis; yeast spores introduced via trauma (eg rose thorn) –> local ulcer with nodules along draining lymphatics; can be disseminated in IC; treat with KI or itraconazole
Protozoa - GI
Giardia (steatorrhea)
Entamoeba histolytica (anchovy paste, liver abscess, dysentery)
Cryptosporidium (severe diarrhea in AIDS)
Protozoa - CNS infections
Toxoplasma gondii (ring-enhancing lesions on CT/MRI, esp in AIDS reactivation) - cysts in meat, cat feces Naegleria fowleri Trypanosoma brucei (African sleeping sickness - ant variation --> recurring fevers; treat with melarsoprol and re
Intestinal Nematodes/Roundworms
Treat with bendazoles
EAT:
Enterobius vermicularis/pinworm - tape test
Ascaris lumbricoides (roundworm)
Trichinella spiralis (undercooked meat)
Larvae penetrate skin –> coughed to lungs:
Strongyloides stercoralis
Ancylostoma duodenale (hookworm) - anemia
Necator (hookworm) - anemia
Tissue nematodes (roundworms)
- Onchocerca (blackfly - river blindness)
- Loa loa (deer, horse, or mango fly; worm in conjunctiva and skin swelling)
- Wucheraria bancrofti (mosquito - elephantiasis from worm in lymphatics)
- Toxocara canis (fecal-oral; larva migrans)
Tx: diethylcarbamazine (ivermectin for onchocerca)
Cestodes (tapeworms)
- Taenia (ingest larvae for intestinal form, eggs for cysticerc)
- Diphyllobothrium latum (fish, B12 def)
- Echinococcus granulosus (dog feces, hydatid cysts in liver)
Tx: praziquantel; albendazole for echinococcus
Schistosoma
Tx: praziquantel
Schistosoma (snail = host; S.mansoni, S. haematobium (SCCA of bladder + pulm HTN)
Clonorchis (from fish, biliary tract inflamm, cholangiocarcinoma)
DNA viruses
- Herpesviruses (1 = oral, 2 = genital, 3 = VZV, 4 = EBV [mono, Burkitt, HL, nasopharyngeal ca; infects B cells and atypical lymphos on smear = reactive T cell; Monospot +], 5 = CMV (AIDS retinitis, PNA; monospot -, owl eye inclusions in infected cells), 6 = roseola, 8 = Kaposi sarcoma); Tzanck test = smear of opened skin vesicle to diagnose, or viral culture for skin/genitalia
- Hepadnavirus (HBV), has reverse transcriptase
- Adenovirus (febrile pharyngitis, acute hemorrhagic cystitis, PNA, conjunctivitis)
- Parvo (B19 - “slapped cheeks” of Erythema Infectiosum/fifth dz, aplastic crisis in SCD, RBC destruction (hydrops fetalis in fetus)) - SINGLE STRANDED
- Papilloma - HPV (16,18 – cervical cancer)
- Polyoma (JC - progressive multifocal leukoencephalopathy in HIV, BK - kidney in transplant pts)
- Poxvirus (smallpox, cowpox, molluscum contagiosum)
RNA viruses
Reovirus - DS - coltivirus (Colorado tick fever) and rotavirus
Single Strand +:
Picorna
- Poliovirus
- Echo (aseptic meng)
- Rhino (common cold)
- Coxsackie (A = hand,foot,mouth; B = pleurodynia, myocarditis)
- Hep A
Hepevirus
Calicivirus (noro)
Flaviviruses (HCV, Yellow fever, Dengue, St. Louis encephalitis, WNV)
Togaviruses (Rubella, EEE/WEE)
Retroviruses (HTLV, HIV)
Coronaviruses (common cold + SARS)
SS -:
Orthomyxo (flu)
Paramyxo (Parainfluenza - croup, RSV - bronchiolitis in babies, Measles/Rubeola - cough, coryza, conjunctivitis, Mumps) - all have surface F protein that –> fusion of resp epith cells into multinucleated cells
Rhabdoviruses (Rabies)
Filoviruses (Ebola/Marburg)
Arena (LCMV, Lassa Fever)
Bunya (California encephalitis, Hantavirus, Rift valley fevers)
Delta (only replicates in presence of Hep B)
Genetic drift vs shift
Drift - small changes based on random mutations in HA (entry) of NA (exit) genes –> EPIDEMICS
Shift - Reassortment of viral genome sequences –> major changes in virus (eg flus) and PANDEMICS
Congenital infections
TORCHES
Toxoplasma - chorioretinitis, hydrocephalus, intracranial calcifications
Rubella - “blueberry muffin rash” (extramedullary hematopoeisis)
CMV - ventricular calcifications, rash, ID
HIV
Syphilis (facial abnormalities/scars, saddle nose, “snuffles,” notched teeth, short maxilla, mulberry molars, saber shins, deafness
Rabies virus
Bullet-shaped
Negri bodies in Purkinje cells of CBL and HC
Long incubation post-exposure, travels to CNS by binding ACh receptors and then migrating retrograde up nerve axons
Sx: fever, malaise –> agitation, photophobia, hydrophobia, hypersalivation –> paralysis and coma –> death
Hepatitis D virus
RNA delta virus
Needs Hep B virus:
- Superinfection (HDV after HBV) - short incubation
- Coinfection (HDV with HBV) - long incubation
Hepatitis E virus
Fecal oral transmission, esp waterborne
RNA hepevirus
Short incubation, no cancer risk
High mortality in pregnant women
ALT vs AST in viral vs. alcoholic hepatitis
Viral: ALT > AST
Alcoholic: AST > ALT
Hepatitis B markers
HBsAg - surface, indicates hep B infection
Anti-HBs - indicates immunity to Hep B
HBcAg - core antigen
Anti-HBc - indicates infection, may be only positive marker during window period b/w acute disease and convalescence
HBeAg - core antigen, indicates active replication and thus high transmissibility
Anti-HBe - low transmissibility
HIV genes
env (gp120 - attach to host CD4 T cells; gp41 - fusion and entry)
gag (p24) - capsid protein
pol - reverse transcriptase
HIV entry into cell
Binds CD4 + coreceptor (CCR5 on macrophages in early disease, CXCR4 on T cells in later disease)
- CCR5 mutation –> decreased susc to HIV
HIV diagnosis
ELISA (high sensitivity); positive result –> Western blot (more specific)
Viral load tests in HIV
Prognostic
AIDS when
HIV diseases with CD4 counts
Atypical pneumonias
Mycoplasma
Legionella
Chlamydia
Bugs that cause osteomyelitis in sickle cell disease
Salmonella, Staph aureus
Three vaginal infections and their differences in inflammation, discharge, histo
Bacterial vaginosis - no inflamm, thin/white discharge with fishy odor, clue cells, high pH
Trichomoniasis (protozoan) - strawberry cervix, grey/green/foul-smelling discharge, motile trichomonads, elevated pH
Candida - inflammation, thick/white/cottage cheese discharge; can see pseudohyphae on slide, normal pH
ToRCHHeS
Toxo - chorioretinits, hydrocephalus and intracranial calcifications
Rubella - PDA, cataracts, deafness
CMV - hearing loss, seizures, periventricular calcifications, petechial rash
HIV - chronic diarrhea, recurrent infxns
Herpes simplex 2 - encephalitis, herpetic lesions
Syphilis - hydrops fetalis; if survives –> facial abnormalities, deafness, saber shins etc
Also Parvo B19 –> hydrops fetalis
Penicillinase resistant penicillins
Dicloxacillin, nafcillin, oxacillin
Narrow spectrum
Bulky R group –> resistance to beta lactamase
Used for staph aureus (not MRSA)
Aminopenicillins
Amoxicillin, ampicillin
- extended spectrum PCN (HHELPSS) + enterococci:
H. flu H. pylori E. coli Listeria Proteus Salmonella Shigella
Abx that block cell wall synthesis
Penicillin
Cephalosporins
Carbapenems
Monobactams
Abx that block folic acid synthesis
Sulfonamides - inhibit folate synthesis by mimicking PABA that inhibit dihydropteroate synthase (Dapsone = closely related - treats lepromatous leprosy); tx for G+, G-, Nocardia, Chlamydia;; can –> hemolysis if G6PD deficient, nephrotox, photosensitivity, kernicturus; res = altered enzyme, decreased uptake, increased PABA synth
Trimethoprim - inhibit dihydrofolate reductase; used with sulfonamides (synergy) for UTIs, Shigella, Salmonella, PJP treatment and prophylaxis, toxo prophylaxis; can –> megalo anemia, leukopenia, granulocytopenia (give folate supplement)
Abx that block DNA topoisomerase
Fluroquinolones - “flox”
Don’t take with antacids!
treat GNR, Neisseria
tox: GI upset, superinfxns, skin rashes, headaches, dizziness; contraind: preg, nursing, kids (may damage cartilage, prolong QT), old people/people on steroids (tendonitis or tendon rupture)
res: mutated target (DNA gyrase), efflux pumps
Abx that damage DNA
Metronidazole
- used for GET GAP (anaerobes below the diaphragm)
Giardia Entamoeba Trichomonas Gardnerella vaginalis Anaerobes
- can –> disulfiram-like rxn (severe flushing, tachy, hypotension) with alcohol
Antibiotics that block RNA synthesis
Rifampin
Antibiotics that block protein synthesis
50S subunit:
chloramphenicol - inhibit peptidyl transferase, used for meng, RMSF but toxic (aplastic anemia and gray baby; res = plasmid-encoded acetyltransferase inactivates drug)
macrolides - “ithromycin” - block peptide transfer/translocation; treat atypical pneumonias, chlamydia, B pertussis; can case arrythmia (increased QT), GI issues, cholestatic hep, rash, eosinophilia; inhibit cyt C; res: methylation of rRNA binding site so drug can’t bind
streptogramin
clindamycin (blocks peptide transfer)
linezolid (prevents formation of initation complex, G+, inc VRE and MRSA; can –> bone marrow supp, peripheral neuropathy; res = point mutation of rRNA)
30S subunit:
- aminoglycosides (inhibit init complex formation); “-micin” + “kacin” - require O2 so ineffective against anaerobes, use for GNR; res = bacterial enzymes inactivate drug; can –> nephrotox, ototox, teratogenic
TCN (inhibit A site t-rna binding, accum intracellularly so good for rickettsia and chlamydia, also borrelia and mycoplasma; can –> GI distress, tooth discoloration, decreased bone growth; resistance = decreased uptake or increased efflux by plasmid-encoded transport proteins)
Cephalosporins
First gen: PEcK
Proteus
E coli
Klebsiella
Second gen: HENPEcKS H. flu Enterobacter Neisseria Proteus E coli Klebsiella Serratia marcescens
Third gen: ceftriaxone, cefotaxime etc
Fourth gen: cefepime (gram neg, esp pseudomonas)
Fifth gen: ceftaroline (broad, inc MRSA, no pseudomonas)
Carbapenems
Broad spectrum, beta lactamase resistant
Administer with cilastatin to inhibit renal metabolism
Lots of side effects (CNS toxicity)
- For gram pos cocci, GNR, anaerobes
Monobactam
Aztreonam
Beta lactamase resistant
Treats GNR only
No cross allergy with PCN
Vancomycin
Inhibits cell wall peptidoglycan by binding D-ala-D-ala (not susc to beta lactamases, but yes to AA modification to D-ala-D-lac
- May –> nephrotox, ototox, flushing (red man syndrome - give antihistamines and slow infusion to prevent)
- Treats G+ only!!
Daptomycin
- lipopeptide (disrupts cell membrane)
- used for GPC, esp Staph aureus
- can –> myopathy, rhabdo
Rifamycins
Rifampin - TB (prophylaxis + tx - induces cyt P450)
Rifabutin - MAC proph/tx
Res: mut decrease drug binding to RNA pol (develops fast)
Kat G
Encodes Bacterial catalase-peroxidase that’s needed to convert isoniazid to active metabolite (used for proph and treatment of TB)
Ethambutol
Decreased carb polymerization of mycobacterium cell wall by blocking arabinosyltransferase
Can –> optic neuropathy
Prophylaxis for endocard/dental procedures
Amoxicillin
Prevention of gonococcal conjunctivitis in newborns
Erythromycin ointment
Prevention of post-surgical infection with Staph aureus
Cefazolin
Prophylaxis of strep (in child with prior RF or pregnant woman)
Penicillin
Amphotericin B mechanism
Binds ergosterol in fungal membrane and makes pores to allow leakage of electrolytes
Keep hydrated to decrease nephrotoxicity, supplement with K and Mg
For serious, systemic mycoses
Class: polyene (also nystatin - too toxic for systemic use; eg “swish and swallow” for thrush)
Azole mechanism
Inhibit cyt P450 that converts lanosterol to ergosterol (some off target –> inhibition of host cytochrome P450, also testosterone synth inhibition)
Terbinafine mechanism
Inhibits fungal squalen epoxidase - used for dermatophytoses (esp oncychomycosis)
Echinocandin mechanism
Inhibit cell wall synthesis in fungi
Used for invasive aspergillosis and candida
“-fungin”
Griseofulvin mechanism
Interferes with MT function –> disruption of mitosis
Treats superficial fungal infxns (eg dermatophytes)
Teratogenic and carcinogenic, induces cyt P450
Nifurtimox - used to treat ____?
T. cruzi treatment
Pyrimethamine - used to treat ____?
Toxo
Suramin and melarsoprol - used to treat ____?
T. brucei
Stibogluconate - used to treat ____?
Leishmaniasis
HIV life cycle and antivirals’ mechanisms at each step
- Fusion - Maraviroc (binds CCR5 - inhibits interaction with gp120) prevents attachment; Enfuvirtide prevents penetration (binds gp41)
- Uncoating and reverse transcription - blocked by NRTIs [all nucleosides except tenofovir, so need to be phosphorylated to be active –> chain term; ZDV (zidovudine/AZT) used for proph and to decrease fetal transmission)and NNRTIs (different binding site from NRTIs, don’t need phosphorylation, may –> rash and hepatotox)
- DNA integration - blocked by integrase inhibitors (“-gravir”) - increase Cr kinase
- transcription
- Translation
- Proteolytic processing - blocked by protease inhibitors (“-navir”)
- Packaging and assembly –> budding –> release
Standard regimen = 2 NRTI + 1 NNRTI or 1 protease inhibitor or 1 integrase inhibitor
Virus life cycles (general) with antiviral mechanisms at each step
- Binding to host cell and endocytosis - blocked by interferon-alpha, which inhibits production of receptor proteins in host (HBV, HCV)
- Uncoating - blocked by amantadine and rimantadine (no longer used for flu b/c of resistance)
- Nucleic acid synthesis (blocked by guanosine analogs - acyclovir [HSV, VZV], ganciclovir [CMV], famciclovir [zoster], only phosphorylated and thus fxal in viral cells (res when this kinase is mutated), can –> kidney pbs if pt isn’t adequately hydrated; viral DNA/RNA pol inhibitors - Cidofovir (nephrotox), Foscarnet [HSV, CMV], res via mutated polymerase; Guanine nucleotide synthesis - Ribavirin [RSV, HCV]
- Virion assembly
- Release of progeny - inhibited by neuraminidase inhibitors (oseltamivir, Zanamivir - used for flu)
Hep C drugs
Ribavirin (inhibits syntehsis of guanine) - teratogen!
Simeprevir (protease inhib) - don’t use as monotherapy! can –> photosens
Sofosbuvir (RNA pol inhibitor) - don’t use as monotherapy!
Abx to avoid in preg
Sulfonamides - kernicterus Aminoglycosides - ototox Fluoroquinolones - cartilage damage Clarithromycin - embryotoxic TCN - teeth, bone growth Ribavirin - teratogen Griseofulvin - teratogen Chloramphenicol - gray baby (lack liver enzyme to metabolize it)
SAFe Children Take Really Good Care
Treatment for local infection with systemic mycoses?
systemic infection?
local = fluconazole or itraconazole
system = “big guns” - aka amphotericin B
Bugs causing brain abscess most commonly
Strep viridans, Staph aureus
if after dental procedure, oral anaerobes
Common causes of meng in newborn? children? adults? elderly?
newborn: GBS, E Coli, Listeria
Kids: Strep pneumo, N meng, HiB, enteroviruses
Adults: Strep pneumo, N. meng, Enteroviruses, HSV2 (1 = encephalitis)
Elderly: Strep pneumo, GNR, Listeria
Common causes of pna - in neonates, kids, adults, elderly
Neonates: GBS, E coli
Kids: viruses (eg RSV), mycoplasma, Chlamydophila, Strep pneumo
Adults (
Amoebas with ingested RBC
Entamoeba
sx = bloody diarrhea, abd cramps, pus in stool, RUQ pain and liver abscesses
tx =metronidazole, iodoquinol
Acid-fast cysts in the stool
Crypto (cysts in water –> diarrhea), Toxo (cysts in raw meat or cat feces)
Macrophages containing amastigotes
Leishmania donovani (transmitted by sandfly)
sx = HSM, malaise, anemia, weight loss
Tear-shaped trophozoites with two nuclei in stool
Giardia
sx = bloating, flatulence, nonbloody diarrhea, steatorrhea
transmitted via cysts in water
Myelin basic protein
may be present in CSF with demyelination (eg with PML from JC virus reactivation)
diag: bx or PCR for JC virus in CSF
protein and glucose in bacterial meng
protein elevated, glucose normal
CMV encephalitis vs PML
CMV - more systemic sx; histo: giant cells with eosinophilic inclusions; enhanicing periventricular WM lesions
PML: nonenhancing T2-hyperintense lesions
