Bacteria Flashcards
5 Morphologic characteristics of Staphylococcus aureus
Gram-positive cocci Catalase+ Coagulase+ Beta-hemolytic Mannitol fermenter (turns salt agar yellow)
Main virulence factor associated with Staph aureus — component of cell wall which binds Fc region of Abs and prevents complement activation thus preventing opsonization and phagocytosis
Protein A
What area of the body does Staph aureus tend to colonize
Nares
8-9 Clinical manifestations of Staph aureus
Post-viral bacterial pneumonia (patchy infiltrate on CXR)
Septic arthritis (MCC)
Large erythematous abscesses
Rapid onset bacterial endocarditis (IV drug use, often tricuspid valve)
Osteomyelitis in adults (MCC)
Scalded skin syndrome, TSS, food poisoning (meats, mayo, salad, cream-filled pastries), MRSA d/t altered cell wall
3 morphologic features of Staphylococcus epidermidis and saprophyticus
Gram+
Catalase+
Urease+
What morphologic feature differentiates staphylococcus aureus from Staph epidermidis and saprophyticus?
Staph aureus is coagulase+
Epidermidis and saprophyticus are coag-
What organism is a part of normal skin flora and tends to infect hardware, orthopedic joints, heart implants, catheters, etc.?
What virulence factor contributes to its ability to do this?
Staphylococcus epidermidis
Ability to form biofilms to stick to metal and plastic surfaces
What organism is associated with contamination of blood cultures
Staph epidermidis
What is the major clinical manifestation of staphylococcus saprophyticus?
UTI’s in sexually active females (2nd most common cause to E.coli)
“Honeymoon cystitis”
Morphologic features of streptococcus pyogenes (group A strep)
Gram+ cocci in chains
Microaerophilic
Hyaluronic acid capsule
Beta-hemolytic
5 Virulence factors associated with S. pyogenes
M-protein (anti-phagocytic, humoral response - Abs to heart) Strep Toxin Streptolysin O Streptokinase DNA-ase
Clinical manifestations of strep pyogenes infection (note which ones are toxin-mediated vs. M-protein mediated)
Pyogenic infections: Impetigo, strep throat, erysipelas, cellulitis
Toxin-mediated: Scarlet fever, TSLS, Necrotizing fasciitis
M protein-mediated: rheumatic fever = arthritis, endocarditis (mitral valve), nodules on extensor surfaces, erythema marginatum, sydenham’s chorea [JONES]
Post-streptococcal glomerulonephritis: facial edema, hematuria, HTN
How would you test for a group A strep infection?
ASO antibody titer
Symptoms of Scarlet fever
Strawberry tongue
Pharyngitis
Widespread rash that spares the face
Which superantigens mediate TSLS vs. Necrotizing fasciitis in strep pyogenes infections?
TSLS = SpeA, SpeC
Nec Fasc = SpeB
Post-streptococcal glomerulonephritis tends to occur after what type of strep pyogenes infection(s)?
Either pharyngitis OR superficial infection like impetigo
Rheumatic fever tends to occur after what type of strep pyogenes infection(s)?
Pharyngitis only (NOT impetigo!)
What organism tends to cause serious infections in newborns, thus pregnant mothers should be swabbed at ~35 weeks?
Streptococcus agalactiae (group B strep)
Morphologic features of strep agalactiae
Gram+ cocci in chains Facultative anaerobe Beta-hemolytic Polysaccharide capsule CAMP test + (increasing zone of hemolysis) Hippurate test +
Clinical manifestations of streptococcus agalactiae
Neonatal meningitis (no nuchal rigidity!)
Strep throat
Pneumonia
Morphologic features of streptococcus pneumoniae
Gram + diplococci Polysaccharide capsule Alpha-hemolytic Facultative anaerobe Optochin-sensitive Bile-soluble
Characteristic feature of otitis media caused by streptococcus pneumoniae
Bullous meringitis
Major virulence factors of strep pneumoniae
Polysaccharide capsule
IgA protease
Diagnosis of strep pneumoniae involves the ____ reaction, which turns blue in the presence of strep pneumo
Quelling
Clinical manifestations of streptococcus pneumoniae
MCC of MOPS:
Meningitis
Otitis media
Pneumonia - often lower lobes, PMN-rich rust-colored sputum
Sinusitis
Morphologic features of streptococcus viridans
Gram+ cocci in chains Facultative anaerobe Alpha-hemolytic Optochin-resistant Bile-resistant No capsule!
Major virulence factor associated with streptococcus viridans
Extracellular dextrans —> adheres to platelets
Clinical manifestations of streptococcus viridans
Dental caries
Subacute bacterial endocarditis (only affects previously damaged heart valve — usually mitral valve)
Morphologic features of S. bovis
Gram+ cocci in chains
Facultative anaerobe
Usually gamma-hemolytic
Grows on bile
Clinical manifestations of S. bovis
Same as enterococcus: subacute bacterial endocarditis, UTI, biliary tract infection
S. bovis has a strong affilitation with what type of neoplasm?
Colorectal neoplasms
Morphologic features of Enterococcus faecalis and faecium
G+ cocci in chains
Facultative anaerobe
Usually gamma-hemolytic
Grows on bile and 6.5% NaCl
[Hugely abx resistant (VRE), nosocomial infections]
Morphologic features of Bacillus anthracis
Gram+ rods in chains (unique!)
Protein capsule (poly-D-glutamate)
Obligate aerobe
Spore-former
Differentiate the 2 toxins associated with bacillus anthracis
Lethal factor — protease exotoxin that causes tissue necrosis via IL-1B and TNF
Edema factor — acts on adenylate cyclase to increase cAMP —> edema (resists phagocytosis)
Complication of GI anthrax
Necrosis of intestines
Characteristic lesion associated with B.anthracis
Black eschar with surrounding erythema
Describe pulmonary anthrax
Caused by spore inhalation (wool sorter’s disease)
Nonspecific symptoms at first, characteristic widened mediastinum on CXR, progresses to pulmonary hemorrhage
Characteristics of bacillus cereus
Aerobic
Spore-forming
Motile
No capsule!
Food poisoning from reheating fried rice — vomiting and diarrhea (heat labile vs. heat stable toxin)
Oxygen-status of all clostridium species
Obligate anaerobes
Morphologic features of Clostridium tetanin
Gram+
Flagellated (H-Ag)
Spore-forming
Describe tetanus toxin associated with Clostridium tetani
Tetanospasmin — released from spores, goes from peripheral motor nerves to spinal cord. Acts as a protease on SNARE, inhibiting GABA and Glycine —> muscle spasm (spastic paralysis)
Characteristic features of C.tetani infection
Spastic paralysis leading to rigidity
Rhesus sardonicus (lock jaw)
Opisthotonus (exaggerated arching of back)
Morphologic fefatures of clostridium botulinum
Gram+
Flagellated (H-Ag)
Spore-former
Clinical features of C.botulinum infection
Adults: DESCENDING flaccid paralysis (only affects PNS), starts with diplopia, ptosis as initial symptoms
Infants: floppy baby syndrome
Pathogenesis of C.botulinum infection in adults vs. infants
Adults: ingestion of preformed toxin (once it has germinated in improperly canned food), toxin then inhibits ACh nerves — toxin is a protease that attacks SNARE protein
Infants: ingest honey that contains SPORES
Morphologic features of Clostridium difficile
Gram+
Spore former
Motile (H-Ag)
Describe exotoxin associated with C.difficile
Exotoxin A = binds brush border — watery diarrhea
Exotoxin B = depolymerizes actin — enterocyte destruction and necrosis —> pseudomembranous colitis
How is C.difficile definitively diagnosed?
Look for toxin via PCR assay of stool
Morphologic features of Clostridium perfringens
Gram+
Spore former
Non-motile!
(found in dirt and soil - associated with combat wounds and motorcycle accidents)
Diseases associated with Clostridium perfringens and their pathogenesis
Gas gangrene (myonecrosis) — crackling sound on palpation d/t alpha-toxin lecithinase that attacks PM leading to RBC hemolysis
Food poisoning — late-onset watery diarrhea — ingest spores which then germinate in gut
Morphologic features of Corynebacterium diphtheriae
Gram+ club-shaped Metachromatic granules (V or Y formation) Bacteriophage-derived toxin Facultative anaerobe Catalase+ Aerosol transmission
Describe the corynebacterium diphtheriae toxin
Acts by ribosylation — inhibits EF-2 to inhibit protein synthesis —> gray pseudomembrane formation over throat and tonsils - can cause airway obstruction and “Bull’s neck” LAD
Other effects: myocarditis, arrhythmia, heart block, local paralysis d/t myelin damage
Diagnosis of C.diptheria requires plating on what media?
How would you differentiate toxic vs. nontoxic strains?
Tellurite and Loeffler’s agar/media
Differentiate strains based on Elek’s test
Morphologic characteristics of Listeria monocytogenes
Gram+ bacilli Beta-hemolytic Motile (H-Ag) — “tumbling” motility Catalase+ Facultative intracellular
Risks for contracting Listeria monocytogenes
Can survive in cold environments — contaminates refrigerated items like milk and soft cheeses
Pregnant women at risk - can give baby meningitis (meningitis also occurs in elderly with this)
What allows L.monocytogenes to escape the phagolysosome?
Listeriolysin O
What conditions are associated with Moxarella catarrhalis infection?
Otitis media in pediatric patients (<3 y/o)
COPD exacerbations and URI/PNA in elderly
Morphologic features of Neisseria
Gram-negative diploccoci
Oxidase+
Since Neisseria cannot be grown on plain blood agar, what are the culture requirements for plating Neisseria?
Chocolate agar (heated blood agar) VPN agar (Thayer Martin)
Virulence factors associated with Neisseria
Pilli — allow attachment to mucosa, antigenic variation
IgA protease — facilitates survival on mucosal surfaces
Opa proteins
Which species of Neisseria is encapsulated (polysaccharide)? How is it transmitted?
Neisseria meningiditis
Spread by respiratory droplets — first colonizes nasopharynx
Neisseria meningiditis ferments ____ and ______. Most infections are caused by type _____ because it is not included in the vaccine. _____ patients are at increased risk for this disease
Glucose; maltose; B; asplenic and sickle cell
Neisseria invades hematogenously leading to a massive immune response generated by what?
LOS proteins in envelope — causes inflammatory response, leaky capillaries, petechial rash indicative of thrombocytopenia (can lead to DIC) —> eventual hypovolemic shock
What is Waterhouse-Fridrichson syndrome?
Occurs with Neisseria meningiditis — characterized by hemorrhage of adrenals
Morphologic features of Neisseria gonorrheae
Gram-negative cocci Facultative intracellular (likes to infect PMNs)
Note that it is NOT encapsulated, and only ferments glucose (unlike N.meningiditis which is encapsulated and ferments glucose+maltose)
Clinical manifestations in N.gonorrheae in males vs. females
Males: urethritis, white purulent discharge —> prostatitis, orchitis
Females: white purulent discharge, PID —> scarring, infertility, ectopic pregnancy, Fitz-Hugh Curtis syndrome (violin string adhesions on liver) = PID spread to peritoneum
Both may exhibit polyarthritis (knees, often asymmetric)
Note that it can also be passed to baby during delivery causing early onset conjunctivitis
Fast vs. slow lactose fermenters
Fast: Klebsiella, E.coli, Enterobacter
Slow: Citrobacter, Serratia
What bacteria are urease+?
Klebsiella pneumoniae
Proteus mirabilis
Helicobacter pylori
Which bacteria exhibit the following diarrheal manifestation:
Lack of cell wall invasion — entertoxin release leads to watery diarrhea
ETEC
Vibrio cholerae
Which bacteria exhibit the following diarrheal manifestation:
Invasion of intestinal epithelium — adhere, invade, toxin release —> system response results in WBC and RBC in stool, fever
EIEC
Shigella
S.enteriditis
Which bacteria exhibit the following diarrheal manifestation:
Invasion of lymph nodes and bloodstream — WBC, RBC, abdominal pain; systemic response can lead to sepsis and bacteremia
S.typhi
Y.enterocolitica
C.jejuni
Describe characteristics of Enterobacter cloacae
Part of normal flora - cause pneumonia, UTI (multi-drug resistant nosocomial infections)
Ferments lactose (forms pink cultures on MacConkey agar)
Motile
Describe characteristics of Serratia marcescens infection
Often infects wounds, causes pneumonia, UTIs (multi-drug resistant nosocomial infections)
Motile; red pigment on culture
Klebsiella pneumoniae is an enteric with the potential to cause pneumonia, UTI, etc. and like other enterics, ferments lactose. What are the other morphologic features of Klebsiella?
Polysaccharide capsule (O-Ag)
Immotile
Urease+
Characteristic findings for someone with a Klebsiella pneumonia
Bulging fissure on CXR
Currant jelly-thick sputum
Cavitary lesions — may originally suspect Tb
Morphologic features of Salmonella typhi
Gram-negative bacilli Motile (H-Ag) H2S positive —> black colonies on Hektoen agar Encapsulated (VI Ag) Acid labile Siderophore Intracellular
Where would you find S.typhi in chronic carriers?
Gallbladder
Clinical features of Salmonella typhi infection
Rose-colored macules on abdomen
Osteomyelitis in pts with sickle cell (MCC)
Pea soup-diarrhea
Morphologic features of Salmonella enteriditis
Gram-negative bacilli Motile H2S+ —> black colonies on Hektoen agar Encapsulated Acid-labile Facultative intracellular (within macrophages) Type III secretion system
Clinical features of Salmonella enteriditis
Acquired by eating undercooked chicken
Causes inflammatory diarrhea
How would you differentiate Shigella from Salmonella infection in terms of plating?
Green colonies on Hektoen agar (Salmonella colonies are black)
Morphologic features of Shigella
Gram-negative bacilli Immotile Acid stable Facultative intracellular within M cells Type III secretion system Shiga toxin
MOA of shiga toxin
Inhibits 60s portion of ribosomes — inhibits translation
Clinical manifestations of shigella infection
Causes bloody diarrhea (inflammatory containing RBCs and WBCs)
Shiga toxin may cause HUS in young patients —> glomerular damage, thrombocytopenia
Morphologic characteristics of E.coli
Gram-negative bacilli Lactose fermenter (pink MacConkey agar) Siderophore Indole+ Green on EMB agar Encapsulated (K-Ag) Catalase+
Which type of E.coli infection is often derived from undercooked meat and causes bloody diarrhea, and is also the only E.coli that does not ferment sorbitol?
EHEC
Describe the toxin associated with EHEC
What strain is associated with outbreaks?
Shiga-like toxin — causes HUS d/t capillary damage in glomerulus —> platelet aggregation and decrease in platelet count, RBC hemolysis
O157:H7 Ag associated with outbreaks
Describe the illness and toxin associated with ETEC
Traveler’s diarrhea from drinking contaminated water - causes watery diarrhea
Heat labile —> increased cAMP (similar to cholera toxin)
Heat stable —> increased cGMP
Characteristics of yersinia enterocolitica
Found in puppy feces and milk products — commonly affects toddlers leading to bloody diarrhea, fever, leukocytosis
Resistant to cold temps
Bipolar (safety pin) staining
Encapsulated
Which bacterial infection can mimic an appendicitis?
Yersinia enterocolitica
Characteristics of Yersinia pestis
Reservoir = rodents, vector = fleas
Bubonic plague —> buboes (LAD)
Endotoxin—>necrosis of tissues
Yops secreted via type III secretion system
Characteristics of Campylobacter jejuni
Thermophilic
Curved gram-negative rod
Oxidase+
Main reservoir = intestinal tract of animals (poultry) - fecal-oral transmission
Clinical manifestations of Campylobacter jejuni
Bloody diarrhea, bacteremia d/t invasiveness, reactive arthritis (Reiter’s)
Post-complication = Guillain Barre —> ascending paralysis
Characteristics of Bacteroides fragilis
Gram-negative bacillus
Anaerobic
Normal flora of GI tract
NO lipid A!
Clinical manifestations of Bacteroides fragilis
Secondary infection following abdominal trauma and/or localized abscesses
May complicate abortion, tubo-ovarian abscess, IUD
Clinical manifestations of Bacteroides melaninogenicus and fusobacterium
Melaninogenicus - can cause a necrotizing anaerobic pneumonia, following GI aspiration; may also exhibit pneumonic and periodontal manifestations
Fusobacterium may have similar disease manifestations and rarely the etiology of otitis media
Characteristics of vibrio cholerae, parahemolyticus, and vulnificus
Gram-negative bacillus
Endemic to developing countries (SE Asia)
“Comma” shaped, grows on alkaline medium (acid labile)
Oxidase+
Transmission and clinical manifestations of vibrio cholerae
Fecal-oral transmission via contaminated food/water - causes profuse watery diarrhea
Main virulence factor and pathogenesis of vibrio cholerae
Fimbriae attach to intestinal wall and toxin is released —> increased cAMP —> secretion of water into lumen
[other virulence factors: mucinase, motile via H-Ag]
What 2 bacteria are at high risk of transmission via contaminated seafood, typically oysters?
Vibrio parahemolyticus and vulnificus
Morphologic characteristics of Helicobacter pylori
Curved Gram-negative bacilli
Motile
Oxidase+
Urease+ (important for reducing acidity of environment)
Clinical manifestations of H.pylori
Duodenal ulcers
Increased risk of gastric adenocarcinoma, MALTomas
Morphologic characteristics of Pseudomonas aeruginosa
Gram-negative rod Oxidase+ Catalase+ Encapsulated Produces pyocyanin and pyoverdin —> blue/green pigment Fruity grape odor Obligate aerobe
What distinguishes psuedomonas aeruginosa from other enterics?
It is an obligate aerobe while most others are facultative anaerobes
Clinical manifestations of pseudomonas aeruginosa
1 cause of gram-negative nosocomial pneumonia
Pulmonary infections in CF patients
Osteomyelitis in IV drug users and diabetics
Complication of burns
Nosocomial UTIs
Ecthyma gangrenosum (black necrotic skin lesions)
Otitis externa
What other toxin is the pseudomonas toxin similar to?
Diphtheria toxin — because it also inactivates EF-2 by ribosylation
Characteristics of proteus mirabilis
Gram-negative rod Urease+ H2S+ Facultative anaerobe Swarming motility, may have fishy odor Staghorn calculi
May cause UTI
Proteus mirabilis cross-reacts with what other bacterial species?
Rickettsia
Characteristics of Bordetella pertussis
Gram-negative rod
Filamentous hemagglutinin pilus attaches to respiratory epithelium and releases toxins
Pathogenesis of Bordetella pertussis toxins
Pertussis toxin:
Ribosylates Gi (disabling it) —> increased cAMP
Lymphocytosis (increased WBC)
AC toxin:
Increases cAMP [edema factor]
Tracheal toxin:
Damages respiratory epithelium
Clinical findings associated with bordetella pertussis
Paroxysmal phase: 1-2 wks of nonspecific findings including conjunctival injection, lacrimation, followed by characteristic cough
Convalescent phase: cough can last months
Characteristics of Haemophilus influenzae
Gram-negative rod Grown on chocolate agar with factor V (NAD+) and X Pilli IgA protease Aerosol transmission
Clinical manifestations of encapsulated Haemophilus influenzae
Epiglottitis: inspiratory stridor, drooling, “cherry-red epiglottis”
Otitis media
Meningitis (type B capsule only - most virulent)
Sepsis, etc. in asplenic or sickle cell patients
Clinical manifestations of nonencapsulated Haemophilus influenzae
Lack of invasiveness, so just causes COPD exacerbations and otitis media
Clinical manifestations of Haemophilus ducreyi
Chancroid (STI) — rapid, unilateral inguinal LAD
Morphologic characteristics of Legionella pneumophilia
Gram-negative rod, but needs silver stain to be visualized
Oxidase+
Charcoal yeast with cysteine+iron for plating
Facultative intracellular
Found in respiratory tract; amoebas
How are infections with Legionella pneumophilia diagnosed?
Rapid urine Ag test
Clinical manifestations of the 2 types of infections with Legionella pneumophilia
Legionnaire’s disease — more common in smokers; atypical pneumonia with unilobar patchy infiltrate, hyponatremia, headache, confusion, diarrhea, fever
Pontiac fever — fever, malaise, cough - more self-limited
Morphologic characteristics of Bartonella henselae infection
Gram-negative rod (zoonotic)
Warthin starry silver stain
What diseases are caused by Bartonella henselae and what are their clinical features?
Cat-scratch disease: fever, regional LNs (axillary), occurs in immunocompetent
Bacillary angiomatosis: also transmitted by cat scratches, occurs in immunocompromised (HIV) — fever, chills, HA, raised red vesicular lesions (similar to Kaposi sarc)
Characteristics of Brucella bordis
Gram-negative rod (zoonotic)
Found in farm animals or in milk/cheese
Facultative intracellular in macrophages
Clinical features of Brucella bordis infection
Since it colonizes macrophages, it causes HSM and LAD
Undulent fever, chills, anorexia
Characteristics of Francisella tularensis
Gram-negative rod
Encapsulated
Facultative intracellular in macrophages
Vectors: ticks and deerfly
Reservoirs: rabbits, squirrels
POTENTIAL BIOTERRORISM AGENT — one of the most infectious pathogenic agents
Clinical features of infection with Francisella tularensis
Ulceroglandular tularemia — Painful ulcer with black base (center with caseating necrosis), fever, LAD, systemic symptoms
Pneumonia tularemia — high mortality rate; via inhalation. Severe atypical pneumonia
Morphologic features of Pastuerella multicoda
Gram-negative rod Catalase+ Oxidase+ Sheep’s blood agar Encapsulated Bipolar staining (safety pin) -like yersinia
Found in respiratory tract of small mammals - cat and dog bites
Clinical features of pasteruella multicoda infection
Cellulitis within 24 hours of bite —> osteomyelitis
What differentiates pasteurella multicoda from other zoonotics?
It is not facultative intracellular
Morphologic features of Mycobacterium tuberculosis
Acid-fast (mycolic acid in cell wall) Carbol fuscin stain Slow growing on Loenstein-Jensen medium Obligate aerobe Facultative intracellular (macrophages)
Virulence factors of Mycobacterium tuberculosis
Cell wall has glycolipids —> cord factor protects from destruction by forming caseating granulomas (tubercles)
Sulfatides prevent phagolysosome fusion
Clinical features of Mycobacterium tuberculosis infection
Transmission via respiratory droplets
Healed primary infection affects lungs (usually lower or middle lobe) and forms Ghon complex affecting hilar LNs. 3 outcomes:
Healed latent infection —> fibrosis and +PPD (type IV HSR)
Systemic infection (miliary Tb) —> fulminant multiorgan failure
Reactivation Tb —> d/t immunosuppression —> TNF activation; affects upper lobes leading to hemoptysis, night sweats, Pots disease, meningitis, tuberculoma
Characteristics of Mycobacterium avium complex
Acquired from environment
Key player for immunocompromised - AIDS pts with CD4<50, elderly smokers
Causes nodularities and bronchiectasis in middle aged non-smokers
Lymphadenitis in kids
Characteristics of Ureaplasma urealyticum infection
Pleomorphic, no cell wall, requires cholesterol, urease
Non-gonococcal urethritis: burning dysuria, yellow mucoid urethral discharge
Characteristics of Mycobacterium leprae
Acid-fast (carbol fuscion stain)
Mycolic acids in cell wall
Thrives in cool temps
Main reservoir: armadillos
Clinical presentation(s) with Mycobacterium leprae infection
Tuberculoid: Th1 cell-mediated — macrophage-contained; well-demarcated skin plaque
Lepromatous: Th2 cells promote humoral response — not contained in macrophages; high chance of human-human transmission, glove/stocking neuropathy, lesions on extensor surfaces, profound facial deformity (leonine facies)
Characteristics of Borrelia burgdorferi
Spirochete
Wright stain and Giemsa stain
Ixodes tick is vector; reservoirs are mice, obligatory hosts are deer
Clinical features of Borrelia burgdorferi infection
- Erythema migrans (bullseye rash), fever, chills
- Heart block (myocarditis), bilateral Bell’s palsy
- Migratory polyarthritis, encephalopathy
Characteristics of Leptospira interrogans
Spirochete
Aerobic
Endemic in tropical areas
Associated with water sports in water contaminated with animal urine
Clinical features of Leptospira interrogans infection
Phase 1 (CSF) - HIGH fever, HA, malaise, myalgias, conjunctival suffusion (no pus)
Phase 2 (immune) - IgM Ab meningismus; renal dysfunction and jaundice from liver damage (infectious jaundice), multiple organ hemorrhage, AMS
Characteristics of Treponema pallidum
Spirochete
Dark field microscopy required, or use VDRL or RPR followed by confirmatory FTA-Ab test
Causes syphilis
Clinical manifestations of adult syphilis
Primary: painless genital chancre - heals in 3-6 weeks
Secondary: systemic: maculopapular rash on palms/soles within weeks to months, condyloma lata on mucous membranes
Tertiary: formation of gummas = soft growths with necrotic firm center, aortitis (tree-barking appearance), destruction of vasa vasorum of aorta —> aneurysm, tabes dorsalis (damage to posterior columns), Argyll Robertson pupils — react to accommodation but not to light
Clinical features of congenital syphilis
Anterior bowing of tibia (saber shins), saddle nose, Hutchinson teeth and Mulberry molars, deafness, hepatomegaly, rhinitis, rash
What is the Jarisch Herxheimer rxn?
When you first treat syphilis with penicillin, symptoms may worsen prior to improving — fever, chills, HA
Characteristics and life cycle of Chlamydia trachomatis
Gram-negative obligate intracellular
No peptidoglycan or muramic acid
Giemsa stain to visualize
Dx with NAAT test
Life cycle:
Elementary body: infectious particle, inhibits phagocytosis
Reticulate body (initial body): forms from EB via binary fission
Clinical features of 3 groups of Chlamydia trachomatis
A-C: blindness
D-K: watery discharge, cervicitis, epididymitis, PID, neonatal transfer—> conjunctivitis, pneumonia
L1-L3: lymphogranuloma venaerum - painless genital ulcer, tender LAD in inguinal region
Complications of C.trachomatis infection
Reactive arthritis (Reiter’s syndrome) “Can’t see, can’t pee, can’t climb a tree” — conjunctivitis, urethritis, arthritis
Fitz Hugh Curtis syndrome (perihepatitis)
Clinical features of Chlamydia pneumoniae and psittaci
pneumoniae: atypical pneumonia - more common in elderly
psittaci: causes pneumonia; transmission by bird droppings
Characteristics and clinical features of coxiella burnetti
Gram negative
Obligate intracellular
Causes Q fever — fever, pneumonia (cough), HA, hepatitis
Contained in spores in animal poop, Aerosol transmission; does not cause rash
Clinical features of Gardnerella vaginalis
Gram negative bacillus that causes bacterial vaginosis (bacterial overgrowth of normal flora)
Vaginal discharge, grayish white with pH 5-6.5, dysuria, pruritis
Dx via KOH whiff test or Clue cells (epithelial cells coated in bacteria)
Characteristics of mycoplasma pneumoniae
No cell wall - won’t gram-stain
Grows on Eatons agar
Only bacteria with cholesterol in cell membrane
Clinical features of Mycoplasma pneumoniae infection
Causes “walking pneumonia” with patchy infiltrate
Increased incidence in young adults and military recruits - close quarters
Dx via cold agluttinins (clumped RBCs in cold temps) - IgM, may also see bullous meringitis on PE
Associated with erythema multiforme and Steven Johnson syndrome
Rickettsia morphology
Gram-negative but doesn’t stain well (pleomorphic)
Obligate intracellular
Unable to produce NAD or CoA
Dx with Weil Felix agluttination test
Clinical features of early undetermined Rickettsia infection
Prodromal headache and fever, vasculitis/rash
Clinical features of Rickettsia prowazekii infection
Rash starting on trunk and spreading to extremities, SPARES hands/feet; myalgia, arthralgia, PNA, encephalitis, dizziness, confusion, coma
Affects military recruits and POWs
Spread by louse poop that gets into scratches
Causes epidemic typhus (OX-19) — widespread rapid outbreak
Clinical features of Rickettsia rickettsii infection
Rocky Mtn Spotted Fever, OX-19, OX-2
Transmission via dermacentor ticks
Rash takes 2-14 days to develop, extends from extremities —> centrally; headache, fever, myalgias
Clinical features of Rickettsia akari infection
Rickettsial pox: mild, self-limiting fever; blister at bite site then vesicular rash and headache — Weil Felix NEGATIVE
What condition is very similar to Rocky Mtn Spotted Fever but is NOT associated with a rash?
Erlichiosis
Morphology of actinomyces israelii
Gram+ filamentous branching rod
Obligate anaerobe
Clinical manifestations of actinomyces israelii infection
Part of normal flora of oral cavity
Jaw trauma (such as with dental work) causes infection. Starts as a lump and proceeds to form abscess. Can then infect sinus tracts and drainage of yellow sulfur granule material
Morphology of Nocardia asteroides
Gram+ filamentous branching rod Weakly acid-fast d/t mycolic acids Obligate aerobe Catalase+ Urease+
Found in soil but does NOT form spores
Why is it significant to note if organisms are catalase+?
People with chronic granulomatous disease (CGD) are at increased risk of infection with catalase+ organisms
Clinical manifestations of Nocardia asteroides
Primarily affects immunocompromised —> HIV pts, transplant pts, pts on glucocorticoids
Affects men > women
3 main sites of infection:
- Pulmonary: PNA with lung abscesses (cavitary lesions)
- CNS: brain abscesses
- Cutaneous: pyogenic, indurated lesions (at risk when dirt gets in wounds)
