BACTERIOLOGY Flashcards
o typhlitis (necrotizing enterocolitis)
o Shanghai fever (mild form of typhoid)
o peritonitis in patients undergoing peritoneal dialysis
Pseudomonas
most common STD overall
CHLAMYDIA TRACHOMATIS
endocarditis in patients who underwent GIT surgery
E. faecalis
type b (polyribitol phosphate) = 95% of invasive disease
H. influenzae
“snow shoe” / “tennis racket” terminal spores
C. tetani
- gram-positive cocci in chains
- Catalase-negative
• Alpha-hemolytic
• Bile and optochin-resistant
VIRIDANS STREPTOCOCCI (S. MUTANS, S. SANGUIS)
paroxysmal pattern of hacking coughs, accompanied by production of copious amounts of mucus, that end with an inspiratory “whoop”
Pertussis or Tuspirina
Scarlet Fever
- postpharyngitic
- due to erythrogenic toxin, seen in lysogenized strains
- fever, strawberry tongue, centrifugal rash (sandpaper-like), Pastia lines, desquamation
S. pyogenes (GAS)
Treatment of Lepromatous leprosy
o dapsone, rifampin, and clofazimine
- types D–K
-
most common cause of STDs
- NGU in males; PID in females
- usual coinfection with gonorrhea
- birth complications
- neonatal conjunctivitis
- neonatal pneumonia
- associated with Reiter syndrome
• Genital Tract Infections sec to C. trachomatis
Exotoxin A of _______ – inhibits elongation factor-2 (EF-2), resulting in decreased protein synthesis in gastrointestinal mucosal
Pseudomonas aeruginosa
SPECTRUM OF DISEASE: LYME DISEASE
- Stage 1: erythema chronicum migrans
- Stage 2: myocarditis (AV block), meningitis, Bell palsy
- Stage 3: autoimmune migratory polyarthritis (onion skin lesions), acrodermatitis chronica atrophicans
BORRELIA BURGDORFERI
Associated with gastric carcinoma and MALT lymphomas
H. pylori
antibiotic-containing selective medium, is used for unsterile specimens (e.g. urethral, endocervical) suspected for N. gonorrhea inf.
Thayer-Martin agar,
- gram-positive cocci in grape-like clusters
- b -hemolytic yellow or golden colonies on blood agar
- catalase-positive
- coagulase-positive
- salt-tolerant on mannitol salt agar (halotolerant)
- “Gold” color is due the pigment staphyloxanthin
STAPHYLOCOCCUS AUREUS
ATYPICAL PNEUMONIA associated with atherosclerosis
CHLAMYDIA PNEUMONIAE
meningococcal vaccine contains capsular polysaccharide of strains
A, C, Y, and W-135
o 3-4 weeks (or longer)
o Diminished paroxysmal cough
o Development of secondary complications (pneumonia, seizure, encephalopathy) in pertussis
Convalescent stage
increases intracellular cAMP in gastrointestinal mucosal cells, resulting in decreased absorption and increased secretion in the digestive tract
Cholera Toxin
MESENTERIC ADENITIS (pseudoappendicitis)
YERSINIA ENTEROCOLITICA
• weakly staining, gram-negative spirochetes
• largest medically-important bacteria
- stain well with aniline dyes (Giemsa or Wright stain)
- cultured on BSK medium
BORRELIA BURGDORFERI
DOC for Lyme disease
doxycycline
bullous impetigo
S. aureus
STAPHYLOCOCCI
most common cause of osteomyelitis in an otherwise healthy patient is
Staphylococcus aureus.
Gas Gangrene
- alpha toxin, a lecithinase that cleaves cell membranes
- Gas produced by anaerobic metabolism
CLOSTRIDIUM PERFRINGENS
Phase of pertussis
o 1-2 weeks
o rhinorrhea, malaise, fever, sneezing, anorexia
o Antibiotics most effective
Catarrhal phase
promote adherence and invasion of N. gonorrhea into epithelial cells; expression results in opaque colonies
Opa proteins
• comma-shaped gram-negative rods
• motile
• oxidase-positive
• cultured on thiosulfate citrate bile salts sucrose (TCBS) agar
• shooting star motility
VIBRIO
influenza-like symptoms few hours after receiving penicillin, due to lysis of treponemes
Jarisch-Herxheimer reaction
classical detection using Weil-Felix reaction - cross-reaction with antigens of OX strains of Proteus vulgaris
RICKETTSIAE
VIRULENCE FACTORS OF S. AUREUS
• Culture: Potassium tellurite: dark black colonies
• Loeffler’s medium: after 12 hours of growth, stain with methylene blue.
C. diphtheriae
o 2-4 weeks
o ‘Whoop’ → burst of non-productive coughs
o Increased number of lymphocytes in blood smear
o Antibiotics ineffective during this stage of pertussis
• Paroxysmal phase
- Gram-positive “lancet-shaped” cocci in pairs or chains
- Catalase-negative
• Alpha-hemolytic
• Bile and optochin-sensitive
• positive Quellung reaction
STREPTOCOCCUS PNEUMONIAE
cell-wall component that prevents phagocytosis in group A streptococci (Streptococcus pyogenes).
Protein M
VIRULENCE FACTORS OF E.COLI
• pili or fimbriae – attachment, colonization factor, associated with UTI (cystitis, pyelonephritis)
• flagellum (H)
• capsule (K) – associated with pneumonia and neonatal meningitis (K1)
• endotoxin (O)
• enterotoxins
- ST and LT cause watery diarrhea, increase cAMP (similar to cholera toxin)
- verotoxin (Shiga-like toxin) causes bloody diarrhea (HUS), inhibits protein synthesis by inactivating the 60S subunit of eukaryotic cells (E. coli O157:H7, STEC, EHEC)
Encapsulated Bacteria
Some Killers Have Pretty Nice and Shiny Bodies.
Streptococcus pneumoniae
Klebsiella pneumoniae
Haemophilus influenzae
Pseudomonas aeruginosa
Neisseria meningitidis
Salmonella typhi
B group streptococci
• sinusitis, otitis media, pneumonia
• meningitis
• epiglottitis - most common cause; cherry red epiglottis; thumb sign
• COPD exacerbations
H. influenzae
most common cause of bacterial gastroenteritis
CAMPYLOBACTER JEJUNI
TRIAD OF BOTULISM
- Symmetric descending flaccid paralysis (with prominent bulbar involvement)
- Absence of fever
- Intact sensorium
most common cause of meningitis among aged 2-18 yrs
N. meningitidis
- gram-positive cocci in chains
- catalase-negative
• beta-hemolytic
• bacitracin-sensitive
• Lancefield group A
• positive PYR test
STREPTOCOCCUS PYOGENES
Vibrio species found in trauma to skin, especially in shellfish handlers, or by ingestion of raw shellfish
V. vulnificus
- anaerobe (normal oral flora)
- setting: local trauma (broken jaw or dental extraction)
- PE: hard, nontender swelling with sinus tracts draining sulfur granules
ACTINOMYCES ISRAELII
Vibrio species contaminated with raw seafood
V. parahaemolyticus)
DOC FOR LEGIONELLA PNEUMOPHILA
azithromycin or erythromycin
False Positive VDRL Results
VDRL
Viruses (EBV, Hepatitis)
Drugs (marijuana)
Rheumatic fever, RA
Lupus, Leprosy
Vector of Lyme disease
bite from deer ticks (Ixodes scapularis, Ixodes pacificus)
BACITRACIN SENSITIVITY
B – BRAS
Bacitracin
group B strep Resistant
group A strep Sensitive
PONTIAC FEVER
LEGIONELLA PNEUMOPHILA
CAT SCRATCH DISEASE
BARTONELLA HENSELAE
- gram-negative rod
- normal oral flora of cats
• cat-scratch fever in immunocompetent individuals
• bacillary angiomatosis in immunocompromised
• transmission: cat bite or scratch
Impetigo contagiosa
S. PYOGENES (GAS)
- perioral blistered lesions with honey-colored crust
- accumulation of neutrophils beneath stratum corneum
- complication: poststrep GN
• comma-shaped gram-negative rods
• microaerophilic
- positive oxidase and catalase tests
- grows well at 42°C on Skirrow agar
CAMPYLOBACTER JEJUNI
Optochin Sensitivity
OVERPASS
Optochin
Viridans = Resistant
Pneumoniae = Sensitive
drug of choice for all rickettsial infections
doxycycline
Scalded Skin Syndrome (Ritter disease)
S. aureus
-
exfoliatin cleaves desmoglein in desmosomes
- separation of epidermis at stratum granulosum
- distinguish from TEN (Lyell disease) where separation occurs at dermo-epidermal junction
most common cause of CAP
S. pneumoniae
o Blood-tinged, pink, or rusty sputum
o Blood cultures often positive
DOC for mycoplasma pneumoniae
erythromycin or azithromycin
• gram-negative “kidney-bean” diplococci
- insignificant capsule
- oxidase-positive colonies on Thayer-Martin medium
• ferment glucose only
. NEISSERIA GONORRHOEAE
- facultative gram-negative rods with large polysaccharide capsule
- extended spectrum beta-lactamase (ESBL) activity in drug resistant strains
• urease-positive
KLEBSIELLA PNEUMONIAE
• facultative gram-negative rods
- lactose-fermenting colonies on EMB or MacConkey agar
- green sheen on EMB agar; metallic sheen
• typing by O and H antigens
ESCHERICHIA COLI
- fever, chills, intense headache
-
calf tenderness
- due to rapid multiplication of leptospires in muscles with high oxygen tension
-
conjunctival suffusion
- due to damaged and leaky conjunctival vessels
- painful and itchy but with minimal tearing
Acute Leptospiremic Phase
What virulence factor causes Typhoid Fever (S. typhi)?
Vi (virulence) capsular antigen
o organisms enter, multiply in Peyer patches, and then spread to reticulo-endothelial system
o predilection for invasion of the gallbladder, which can result in establishment of the chronic carrier state
LACTOSE FERMENTERS
LaCtose is KEE. Grow in MacConKEE agar.
Citrobacter
Klebsiella
Escherichia coli
Enterobacter
most important virulence factor of TB
cord factor
o inhibits WBC migration
o causes characteristic serpentine growth pattern
o induces TNF-α release
for detection of toxigenicity of C. diphtheriae
modified Elek test
Treatment of Cholera
-
Cholera
- fluid and electrolyte replacement
- tetracycline or azithromycin shortens duration
-
V. parahaemolyticus, V. vulnificus Infection
- minocycline plus fluoroquinolone or cefotaxime
- thin, coiled spirochetes
- hook at one or both pointed ends (Shepherd’s crook)
- obligate aerobe
- grown on Ellinghausen-McCullough-Johnson-Harris (EMJH) medium or Fletcher medium
LEPTOSPIRA INTERROGANS
all pregnant women should be screened for GBS colonization at what AOG
35-37 weeks AOG
• aerobic, acid-fast rods
o Ziehl-Neelsen (or Kinyoun)
• high lipid content
o mycolic acids and wax D
- produces catalase and niacin
- slow-growing on Löwenstein-Jensen medium
• luciferase assay for drug resistance
MYCOBACTERIUM TUBERCULOSIS
- infections commonly due to combinations of bacteria in synergistic pathogenicity
- LPS with low endotoxic activity
- capsule (antiphagocytic and anticomplement)
- foul-smelling discharge → because of short-chain fatty-acid products of fermentation
BACTEROIDES FRAGILIS
antibodies decrease efficacy of streptokinase in managing MI
anti-streptokinase
Marantic endocarditis AKA nonbacterial thrombotic endocarditis (NBTE) in patients with abdominal malignancy
Strep bovis
GRAM NEGATIVE RODS - GIT AND GUT
- anaerobic, gram-positive, spore-forming rods
- double hemolysis on blood agar
- growth on egg-yolk agar - nonmotile but with rapidly spreading growth on culture media
CLOSTRIDIUM PERFRINGENS
DOC for cutaneous anthrax
ciprofloxacin
NOVOBIOCIN SENSITIVITY
NO StRES
NOvobiocin
Saprophyticus Resistant
Epidermidis Sensitive
ANTIBIOTICS FOR ACTINOMYCETES
S–N–A–P
Sulfa for Nocardia; for Actinomyces, use Penicillin.
Which capsular type of Neisseria meningitidis lacks immunogenicity even with protein conjugation, hence, not included in the vaccine?
B
• non-lactose-fermenting, gram-negative rods
• produce no gas from the fermentation of glucose
• do not produce H2S
• nonmotile
- have O antigens
- cultured in XLD medium
SHIGELLA SPP.
cultured in Eaton’s agent - requires cholesterol and nucleic acids; penicillin is added to inhibit growth of contaminating bacteria; dome-shaped colonies with “fried egg” appearance or “mulberry” appearance (in the case of Mycoplasma pneumoniae)
Mycoplasma pneumoniae
DOC for Salmonella
Ceftriaxone
Philippines: amoxicillin, chloramphenicol, co-trimoxazole
TULAREMIA
FRANCISELLA TULARENSIS
- small gram-negative rods
- reservoir: rabbits, deer, and rodents
- transmission: ticks (e.g., Dermacentor), aerosols, contact, and ingestion
- treatment: streptomycin or gentamicin
• Pneumonia
o thick, bloody sputum (“currant-jelly” sputum)
o usually nosocomial
o most common cause in alcoholics
Klebsiella pneumoniae
REITER SYNDROME
Triad of urethritis, uveitis, and arthritis
CAN’T PEE
CAN’T SEE
CAN’T CLIMB A TREE
o clinically similar but milder than S. aureus TSS
o due to pyrogenic exotoxin A
o recognizable site of pyogenic inflammation
o blood cultures are often positive
Streptococcal Toxic Shock Syndrome
-
ecthyma gangrenosum
- hemorrhagic lesions
-
febrile neutropenia
- leukemia or lymphoma post chemo- or radiation therapy
- severe burns
Pseudomonas
- aerobic, filamentous gram-positive rods with aerial hyphae
- weakly acid-fast (Fite-Faraco)
- transmission: inhalation of particles from soil
- manifests as mycetomas and lung and brain abscesses (orange colonies)
- treatment: TMP-SMX + drainage
NOCARDIOSIS
(NOCARDIA ASTEROIDES)
most common cause of urethritis
Gonococcal Urethritis
o post-impetigo (commonly the M12 type) OR postpharyngitic
o M protein incites immune complex deposition on the glomerular basement membrane
o ssx: hypertension, periorbital edema, hematuria
PSAGN
o most common bacterial cause of sore throat
o inflammation, exudate, fever, leukocytosis, and tender CLAD
o pyogenic complications: peritonsillar and retropharyngeal (Quincy) abscess, otitis, sinusitis, meningitis
S. pyogenes (GAS)
Floppy Baby Syndrome
- when babies ingest spores found in household dust or honey
- due to absence of competitive bowel microbes
Infant Botulism
most common cause of acute endocarditis
S. aureus
Virulence factors of Pseudomonas
- endotoxin
-
exotoxin A
- tissue necrosis and inactivates EF-2
- type III secretion system facilitates exotoxin transfer
- elastase and proteases
- pyocyanin damages the cilia and mucosal cells
- verdoglobin from hemoglobin breakdown → any of several green compounds derived from hemoglobin or related compounds by cleavage of the porphyrin ring
Virulence factors of MYCOPLASMA PNEUMONIAE
-
toll-like receptor 2 protein (P1 adhesin)
- attachment, inhibition of ciliary motion and necrosis
-
hydrogen peroxide
- contributes to the damage to the respiratory tract cells
- autoantibodies against red cells (cold agglutinins) and brain, lung, and liver cells
FACULTATIVE INTRACELLULAR BACTERIA
Some Bugs May Live FacultativeLY.
Salmonella
Brucella
Mycobacterium
Listeria
Francisella
Legionella
Yersinia
• IgA protease for colonization
• c-substance reacts with CRP
S. pneumoniae
ABCDEFG of Diphtheria
ADP-ribosylation
Beta-prophage
Corynebacterium
Diphtheriae
Elongation Factor-2
Granules (metachromatic)
For N. gonorrhea, sterile clinical specimens (e.g. blood, synovial fluid, CSF) should be inoculated onto
enriched chocolate agar
GRAM POSITIVE BACTERIA
MEMOOORRRIIIIZZZEEEE!!!!
DOC for Shigella
ciprofloxacin
injection of diphtheria exotoxin into the skin, to determine whether a person is susceptible to infection by diphtheriae (not to be confused with Dick test in scarlet fever)
Schick test
Q fever
Coxiella burnetti
- anaerobic, gram-positive, spore-forming rods
- spore is at one end (terminal spore) so organism looks like a tennis racket
CLOSTRIDIUM TETANI
o triggers cell-mediated immunity in TB→ caseation and granulomas
o triggers delayed hypersensitivity reaction
o a surface protein
tuberculin surface protein
• gram-negative “kidney-bean” diplococci
- large polysaccharide capsule
- oxidase-positive colonies on chocolate agar
• ferments maltose and glucose
NEISSERIA MENINGITIDIS
FORMS OF CHLAMYDIA
Elementary body = Enfectious, Enters cell via Endocytosis
Reticulate body = Replicates in cell by fission
o within hours, enters lymphatics and multiplies
o local, nontender ulcer (chancre) usually forms in 2–10 weeks
o Highly infectious, heals spontaneously in 3-6 weeks
Primary Syphilis
DOC for S. pyogenes (GAS)
Penicillin G
Osteomyelitis in IV drug abusers
- Staphylococcus aureus
- Pseudomonas aeruginosa
C. difficile exotoxins A (enterotoxin) and B (cytotoxin) inhibit GTPases, leading to apoptosis and death of enterocytes leading to ___
pseudomembranes
- many years after inoculation
- clinical spectrum
- granulomas (gummas)
-
neurosyphilis
- tabes dorsalis
- Argyll-Robertson pupil / Prostitute’s pupil
- dementia paralytica
- cardiovascular (aortitis)
- obliterative invasion of small blood vessels and vasa vasorum, causing endarteritis
Tertiary Syphilis
LYME DISEASE
BAKE a Key LYME pie
Bell Palsy
Arthritis
Kardiac block
Erythema chronicum migrans
Toxic Shock Syndrome
S. aureus
- due to TSST-1
- fever, hypotension, sloughing of the filiform papillae → strawberry tongue, desquamating rash and multi-organ involvement (>3)
- usually no site of pyogenic inflammation; blood CS negative
- usual scenario: tampon-using menstruating women or in patients with nasal packing for epistaxis
Ehrlichiosis
Ehrlichia chaffeensis
o Non-bloody diarrhea associated with pseudomembranes (yellow-white plaques) on the colonic mucosa
o toxic megacolon can occur
Pseudomembranous Colitis
- C. trachomatis types L1–L3
- papule or vesicular which ulcerates and leads to suppurative inguinal lymphadenitis (buboes)
- positive Frei test
- intradermal injection of antigen
Lymphogranuloma Venereum
- aerobic, non-spore-forming, gram-positive rods
- arranged in V- or L-shape
• tumbling motility
• narrow zone of beta-hemolysis
• cold enhancement: paradoxical growth in cold temperature
LISTERIA MONOCYTOGENES
Reddish metachromatic (Babes-Ernst / Volutin) granules can be seen
C. diphtheriae
- aerobic, gram-positive box-car like rods
- nonmotile
- spore-forming
- Medusa head morphology - dry “ground glass” surface and projections along lines of inoculation
BACILLUS ANTHRACIS
2nd most common cause of UTIs in sexually active women
STAPHYLOCOCCUS SAPROPHYTICUS
- Seen in lepromatous form
- Tender red nodules or humps on both shins
- Signals acute flare-ups of disease
- Treated with Thalidomide → category X drug; associated with phocomelia if given during pregnancy
Erythema Nodosum Leprosum
- most common cause of crippling of the hand
- Damage in the following nerves is characteristic impairments in leprosy:
- Ulnar and median: clawed hand
- Posterior tibial: plantar insensitivity and clawed toes
- Common peroneal: foot drop
- Radial cutaneous, facial, and greater auricular nerves (may also be involved)
Leprosy / Hansen Disease
most commonly identified cause of GBS
Campylobacter infection
Thayer-Martin agar composition
Mueller-Hinton agar with 5% chocolate sheep blood plus the following antibiotics (VPN):
- Vancomycin (inhibits gram-positive organisms)
- Polymyxin* inhibits gram-negative organisms excluding Neisseria species)
- Nystatin (inhibits fungi)
*Alternatively, polymyxin can sometimes be replaced with colistin (hence, VCN) or trimethoprim.
Which of the following refers to an obsolete skin test for venereal lymphogranuloma that uses antigens prepared from chlamydia grown in the yolk sac of a chick embryo?
Frei test
- poorly gram-negative rods
- visualize with silver stain
- facultative intracellular bacteria
- culture on charcoal yeast extract agar
- increased amounts of iron and cysteine
- optimal between 28 and 40°C; organisms are dormant below 20°C and are killed at temperatures above 60°C
- rapid urinary antigen test
LEGIONELLA PNEUMOPHILA
Epidemic Typhus
Rickettsia prowazekii
o watery diarrhea in large volumes (rice-water stools)
o patients with severe hypovolemia may have sunken eyes, dry mouth, cold clammy skin, decreased skin turgor, or wrinkled hands and feet, aka ‘washerwoman’s hands’
Cholera
- gram-positive cocci in chains
- catalase-negative
• gamma hemolytic colonies
• Lancefield group D
• bile and optochin-resistant
• hydrolyzes esculin in bile-esculin agar (BEA)
• positive PYR test
• E. faecalis can grow in 6.5% NaCl while S. bovis cannot
GROUP D STREPTOCOCCI
bird fancier’s disease - sudden onset pneumonia with malaise, fever, anorexia, sore throat, photophobia, and severe headache
CHLAMYDIA PSITTACI
satellite phenomenon around S. aureus colonies - hemolysis by S. aureus liberates factor V
H. influenzae
DOC for Pseudomembranous Colitis
oral metronidazole or vancomycin should be given and fluids replaced - oral vancomycin because it has poor intestinal absorption, hence, it ‘coats’ the lesions with antibiotic
- gram-positive cocci in clusters
- catalase-positive
• coagulase-negative
• novobiocin-sensitive
• whitish, non-hemolytic colonies on blood agar
STAPHYLOCOCCUS EPIDERMIDIS
Two genera of bacterial pathogens are known to produce endospores:
aerobic Bacillus and anaerobic Clostridium
exotoxin inhibits protein synthesis by adding ADP-ribose to elongation factor-2 (EF-2)
o subunit A, has ADP-ribosylating activity
o subunit B, binds the toxin to cell surface
o exotoxin encoded by b -prophage
C. diphtheriae
GRAM NEGATIVE BACTERIA
MEMMMOOOORRRIIIZZZEEEE!!!
o most severe form of meningococcemia
o high fever, shock, widespread purpura, disseminated intravascular coagulation, thrombocytopenia, and adrenal insufficiency
§ bilateral hemorrhagic destruction of the adrenal glands
Waterhouse-Friderichsen Syndrome
OSTEOMYELITIS in burns
Pseudomonas aeruginosa
- gram-positive cocci in chains
- Catalase-negative
• Beta-hemolytic
• Bacitracin-resistant
• Lancefield group B
- hydrolyze hippurate
- CAMP test–positive
- grow using Lim broth
STREPTOCOCCUS AGALACTIAE
(GROUP B STREPTOCOCI)
S. pyogenes preotein that prevents phagocytosis by binding to the Fc region of IgG
Protein A
o postpharyngitic
o cross-reacting antibodies to M proteins and antigens of joint, heart, and brain tissue
o Jones Criteria:
§ migratory polyarthritis
§ pancarditis
§ erythema marginatum
§ Sydenham chorea
§ subcutaneous nodules
Acute Rheumatic Fever sec to S. pyogenes (GAS)
- small gram-negative rod
- culture on chocolate agar with heme (factor X)
- PE: painful genital ulcer
CHANCROID
(HAEMOPHILUS DUCREYI)
Pseudomonas susceptible drugs
o antipseudomonal penicillins (ticarcillin, piperacillin)
o penicillin plus beta-lactamase inhibitor (ticarcillinclavulanate, piperacillin-tazobactam)
o third generation cephalosporins (ceftazidime)
o fourth generation cephalosporins (cefepime)
o monobactam (aztreonam)
o carbapenems (imipenem, meropenem)
o fluoroquinolones (ciprofloxacin)
OBLIGATE INTRACELLULAR BACTERIA
Stay inside cells when it is Really Cold
Ricketssia
Chlamydia
blocks acetylcholine release causing flaccid paralysis (descending pattern)
botulinum toxin (heat-labile neurotoxin)
• culture on Bordet-Gengou agar or Regan-Lowe charcoal medium
BORDETELLA PERTUSSIS
ABCDE of beta-prophage encoded toxins
ShigA-like toxin (EHEC)
Botulinum toxin
Cholera toxin
Diphtheria toxin
Erythrogenic toxin (S. pyogenes)
o nosocomial pneumonia, VAP, necrotizing pneumonia, complicated by empyema, abscess or pneumatocele
o post-viral pneumonia
S. aureus
o bacteremia results in the seeding of many organs, with osteomyelitis, pneumonia, and meningitis as the most common sequelae
o commonly in patients with sickle cell anemia or cancer
Salmonella choleraesuis
• smallest free-living organisms
• not seen on Gram-stain
o no cell wall
o only bacteria with sterol in cell membrane
MYCOPLASMA PNEUMONIAE
Exotoxin A and B - cause depolymerization of actin filaments in gastrointestinal mucosal cells, leading to mucosal cell death (i.e. pseudomembranes)
Clostridoides difficile
Cellulitis
S. pyogenes and Staphyloco
§ deeper infection involving subcutaneous/dermal tissues
§ facilitated by hyaluronidase (spreading factor)
VIRULENCE FACTORS OF S.PYOGENES / GROUP A STREP
- Osteomyelitis & Septic Arthritis
- from hematogenous spread or local introduction at wound site
-
Brodie abscess
- sequestered focus of osteomyelitis arising in the metaphyseal area of a long bone
S. aureus
(woolsorter’s disease)
BACILLUS ANTHRACIS
method of determining susceptibility to scarlet fever by injection into the skin of 0.1 cubic centimetre of scarlet fever toxin (do not consufe this with the Schick test for diphtheria susceptibility)
Dick test
treatment of erythema nodosum leprosum
thalidomide
Virulence factors of LISTERIA MONOCYTOGENES
• internalin: interacts with E-cadherin on the surface of cells
• listeriolysin: escape from phagosomes
• actin rockets (actin polymers): propels the bacteria through the membrane of one human cell and into another
cultured in mouse footpad or in the armadillo
MYCOBACTERIUM LEPRAE
DOC for pertussis
Erythromycin
UNDULATING FEVER
BRUCELLA ABORTUS
- transmission: contaminated dairy or direct contact
- treatment: doxycycline plus rifampin
Enterotoxin produced by B. cereus
Heat-Labile Enterotoxin
o cholera-like enterotoxin causes ADP-ribosylation, increasing cAMP
o most severe form of leptospirosis
o triad: jaundice, bleeding, uremia
o orange cast skin (severe jaundice)
o most common cause of death is respiratory failure due to massive pulmonary hemorrhage
Weil Syndrome
Endemic typhus
Rickettsia typhi
- anaerobic, gram-positive, spore-forming rods
- exotoxin in stool detected by cytopathic effect (final phase by which viral cells infect cells) on cultured cells or ELISA
CLOSTRIDIUM DIFFICILE now CLOSTRIDIOIDES DIFFICILE
- Ubiquitous in man and natural water environments
- Freshwater amoebae appear to be the natural reservoir for the organisms.
- transmission via aerosol (e.g. AC, cooling towers)
- person-to-person transmission does not occur
LEGIONELLA PNEUMOPHILA
• most virulent bacteria
- small gram-negative rods with bipolar (safety pin) staining
- reservoir: wild rodents
- transmission: flea bite, inhalation
- PE: buboes, cutaneous hemorrhage
- treatment: streptomycin and tetracycline
- No vaccine available
YERSINIA PESTIS
antiphagocytic capsule of B. anthracis
poly-D-glutamate)
titers to document antecedent skin infection
anti-DNAse B
GRAM POSITIVE RODS
UREASE-POSITIVE BACTERIA
Particular Kinds Have Urease.
Proteus mirabilis
Klebsiella pneumoniae
Helicobacter pylori
Ureaplasma urealyticum
- most common type of atypical pneumonia (walking pneumonia)
- clinical findings not compatible with chest x-ray
• extra-pulmonary manifestations:
o hemolysis, Stevens-Johnson syndrome, Raynaud, GuillainBarre syndrome
MYCOPLASMA PNEUMONIAE
BITES and OSTEOMYELITIS
- short, encapsulated gram-negative rod that exhibits bipolar staining (‘closed safety pin appearance’)
- buttery colonies with musty odor due to indole production
- reservoir: cats and dogs
- transmission: animal bites
- treatment: penicillin G
PASTEURELLA MULTOCIDA
MCC of neonatal pneumonia, sepsis and meningitis
STREPTOCOCCUS AGALACTIAE
(GROUP B STREPTOCOCI)
• urease hydrolyzes the urea in urine to form ammonia
o raises pH producing alkaline urine
o encourages the formation of struvite stones, composed of magnesium-ammonium-phosphate
PROTEUS MIRABILIS
ATYPICAL PNEUMONIA
- pneumonia accompanied by confusion, non-bloody diarrhea, hyponatremia, proteinuria and hematuria
LEGIONELLA PNEUMOPHILA
NEONATAL MENINGITIS
B–E–L
B group streptococci (S. agalactiae)
Escherichia coli
Listeria monocytogenes
DOC of MRSA
Vancomycin
• facultative gram-negative rods
• non-lactose-fermenting
- produces H2S
- Widal test detects antibodies in patient’s serum
- cultured in XLD medium
SALMONELLA SPP.
What is the vector of plague (Yersinia pestis)?
FLEA
granulomatosis infantiseptica
o transplacental transmission
o characterized by late miscarriage or birth complicated by sepsis, multiorgan abscesses, and disseminated granulomas
Early-Onset Neonatal Listeriosis
- facultative gram-negative rods
- non-lactose-fermenting
• urease-positive
• swarming motility
PROTEUS MIRABILIS
Drugs associated with Psudomembranous colitis secondary to C. difficile
clindamycin, 2 nd & 3 rd gen cephalosporins, ampicillin
-
tracheal cytotoxin
- damages ciliated cells
- causes whooping
-
extracytplasmic (false) adenylate cyclase
- ‘weakens’ neutrophils lymphocytes and monocytes
- inhibits phagocytosis
-
filamentous hemagglutinin
- pili rod that extends from the surface of B. pertussis, enabling the bacteria to bind to ciliated epithelial cells of the bronchi
- mediates attachment
-
pertussis toxin
- causes ADP-ribosylation
- activates G proteins that increases cAMP resulting in:
BORDETELLA PERTUSSIS
o central area of Langhan giant cells surrounded by a zone of epithelioid cells
o tubercle is a granuloma surrounded by fibrous tissue that has undergone central caseation
Granulomatous Lesions in TB
- may mimic ulcerative colitis
- disease associations
-
Guillain-Barré syndrome
- antigenic cross-reactivity between oligosaccharides in bacterial capsule and glycosphingolipids on surface of neural tissues
-
Guillain-Barré syndrome
- reactive arthritis (Reiter syndrome)
CAMPYLOBACTER JEJUNI
Methicillin resistance in S aureus is mediated by what gene?
mecA gene
* encodes for a novel penicillin-binding protein (PBP), PBP2a, with reduced binding affinity for antibiotic.
§ most severe form of bacillary dysentery
§ most common cause of epidemic dysentery
Shigella dysenteriae type 1 – Shiga bacillus
o condyloma lata, maculopapular rash, fever headache, malaise, anorexia, lymphadenopathy
o occurs after 1 to 3 months
Secondary Syphilis
gold standard for leptospirosis diagnosis
leptospire microscopic agglutination test (lepto MAT)
DOC for Tetanus
Metronidazole or penicillin - Metronidazole (400mg rectally or 500 mg IV every 6 h for 7 days) is the preferred antibiotic. An alternative is penicillin (100,000–200,000 IU/kg per day), although this drug theoretically may exacerbate spasms (Harrisons)
Necrotizing fasciitis AKA flesh-eating disease
S. pyogenes (GAS)
- rapidly progressive infection of deep subcutaneous tissues
- facilitated by exotoxin B
-
Fournier’s gangrene
- form of necrotizing fasciitis involving the male genital area and perineum; often caused by mixed organisms but can be caused by GABHS
STREPTOCOCCI - OVERVIEW
- encapsulated, pleomorphic gram-negative bacillus
- bipolar densities (Donovan bodies) look like closed safety pins
- small painless papule ulcerates to form beefy red ulcer with velvety surface
- pseudobuboe formation → lump in the groin similar in appearance to bubo (remember bubonic plague?); it is actually a granuloma and not an inflamed lymph node, hence, it is a ‘false’ bubo
- treatment: azithromycin
GRANULOMA INGUINALE /DONOVANOSIS
(KLEBSIELLA GRANULOMATIS)
NEISSERIA
Neisseria MeninGitidis ferments Maltose and Glucose
Neisseria GOnorrhoeae ferments Glucose Only
BUBONIC, PNEUMONIC and SEPTICEMIC PLAGUE
YERSINIA PESTIS
• ingestion of unpasteurized milk products, e.g., cheese
LISTERIA MONOCYTOGENES
Rockey mountain Spotted fever
Rickettsia rickettsii
ZOONOSES
Bugs From Your Pets.
Brucella abortus
Francisella tularensis
Yersinia pestis
Pasteurella multocida
TETANUS PROPHYLAXIS
DRUGS USED IN TB TREATMENT
DOC of VRSA
Linezolid
prevents phagosome-lysosomal fusion in TB
exported repetitive protein (sulfatides)
• most common cause of
o prosthetic valve endocarditis
o septic arthritis in prosthetic joints
o ventriculoperitoneal shunt infections
S. Epidermidis
protein complex responsible for the massive, watery diarrhea (e.g. rice water stools) characteristic of cholera infection
Cholera toxin (a.k.a. choleragen, sometimes abbreviated as CTX, Ctx or CT)
- CT acts by causing constitutive activation of adenylate cyclase, leading to elevated cAMP levels in intestinal epithelial cells. Cyclic AMP (cAMP) activates protein kinase A, which causes the opening of ion channels in the membrane, leading to chloride and bicarbonate secretion by intestinal crypt cells and disruption in absorption by villus cells.
Halberstaedter-Prowazek inclusions
C. trachomatis
LEPTOSPIROSIS PHASE?
- aseptic meningitis
- CSF pleocytosis with or without meningeal symptoms
- coincides with appearance of antibody titers
- pulmonary involvement
- snow-flake lesions in CXR
- hepatic necrosis
- glomerulonephritis
- due to immune-complex deposition
Immune Leptospiruric Phase
most common cause of bacillary dysentery
Shigella sonnei – Duval’s bacillus
Neonatal Pneumonia
- types D–K
- late-onset (2-4 weeks) o striking tachypnea, characteristic paroxysmal cough (staccato cough), absence of fever, and eosinophilia
C. trachomatis
The heat resistance of bacterial spores, such as those of B. anthracis, is due in part to their dehydrated state and in part to the presence of large amounts of which of the following?
Calcium dipicolinate
* Dipicolinic acid forms a complex with calcium ions within the endospore core. This complex binds free water molecules, causing dehydration of the spore.
• looks like Chinese characters
• metachromatic granules
C. diphtheriae
- gram-negative rods
- obligate aerobe
• non-lactose-fermenting
• oxidase-positive
• pyocyanin (blue-green pigment)
• sweet grape-like odor
• grown on Cetrimide agar
PSEUDOMONAS AERUGINOSA
VIRULENCE FACTORS OF VIBRIO
- enterotoxin (choleragen) acts by ADP ribosylation
- mucinase enhances attachment to the intestinal mucosa
- high infectious dose
- pandemics caused by Vibrio cholerae O1 biotype El Tor (cholera El Tor)
- glycocalyx adheres well to foreign bodies and form biofilms
- prosthetic heart valves
- prosthetic joints
- ventriculoperitoneal shunts
- indwelling catheters
STAPHYLOCOCCUS EPIDERMIDIS
tetanus toxin
tetanospasmin
o protease that cleaves proteins involved in the release of glycine from Renshaw cells in spinal cord
o Prevents release of GABA by cleaving of synaptobrevin 2
only bacteria with sterol in cell membrane
MYCOPLASMA PNEUMONIAE
TRACHOMA = TYPES A, B, C
ABC:
Africa
Blindness
Chronic infection
DOC of inhalational/gastrointestinal anthrax
DOC is ciprofloxacin or doxycycline with one or two additional antibiotics (rifampin, vancomycin, penicillin, imipenem, clindamycin, clarithromycin)
GROUP A STREP TOXINS
o alkaline vegetables such as green beans, peppers, and mushrooms
o smoked fish
o canned goods (bulging)
o honey
CLOSTRIDIUM BOTULINUM
cause pulmonary disease in immunocompromised hosts (AIDS patients with CD4 <50)
MYCOBACTERIUM AVIUM-INTRACELLULARE COMPLEX (MAI, MAC)
- gram-positive cocci in clusters
- catalase-positive
• coagulase-negative
• novobiocin-resistant
- whitish, non-hemolytic colonies on blood agar
- Nitrite negative (unlike E. coli)
STAPHYLOCOCCUS SAPROPHYTICUS
titers to document antecedent pharyngitis
anti-streptolysin O (ASO)
direct epidermal contact with spores causes formation of a malignant pustule with subsequent eschar and central necrosis
Cutaneous Anthrax
most common cause of subacute and native endocarditis
S. sanguis (VIridans Strep), for subacute bacterial endocarditis (SBE)
most common cause of septic arthritis in sexually active adults
N. gonorrhea
• curved gram-negative rods
• urease-positive
• microaerophilic
HELICOBACTER PYLORI
MCC of death is pulmonary hemorrhage in the ff:
• Anthrax (pulmonary) aka wool sorter’s disease
• Leptospirosis, severe (Weil’s syndrome)
• Congenital syphilis
allows adherence of bacteria to the mucous membranes of the respiratory, genitourinary and gastrointestinal tracts
IgA protease
• Skin & Soft Tissue Infections
o bullous impetigo, folliculitis, furuncles, carbuncles, cellulitis, hidradenitis suppurativa, mastitis, surgical site infections
S. aureus
cause culture negative subacute bacterial endocarditis in patients with preexisting heart disease
HACEK ORGANISMS
Haemophilus aphrophilus
Actinobacillus actinomycetemcomitans
Cardiobacterium hominis
Eikenella corrodens
Kingella kingae
o snuffles / saddle nose
o mulberry molars
o Hutchinson triad: Hutchinson teeth, deafness, keratitis
o saber shins
o rhagades (angle of mouth)
o Higoumenakis sign (clavicle) → unilateral enlargement of the sternoclavicular portion of the clavicle, leads to detachment
o Clutton’s joints (synovitis)
o pulmonary hemorrhage
Congenital Syphilis
Treatment of tuberculoid leprosy
dapsone and rifampin
o acute onset (4 hrs) of vomiting and diarrhea due to ingestion of preformed heat-stable enterotoxin
o source: salad made with mayonnaise (potato or tuna salad)
Gastroenteritis sec to S. aureus
ENTEROBACTERIACEAE
• obligate intracellular bacteria
• energy parasites that use host ATP
- cell wall lacks muramic acid
- grown in cycloheximide culture
• cytoplasmic inclusions in Giemsa
CHLAMYDIA TRACHOMATIS
Erysipelas AKA St. Anthony’s Fire
S. pyogenes (GAS)
superficial infection extending into dermal lymphatics
Virulence factors of B. anthracis
Bacillary angiomatosis presents with cutaneous nodules very similar in appearance to those found in which disease?
Kaposi sarcoma
Shiga-like toxin (just like the real Shiga toxin produced by Shigella) inhibits ____ ribosomal subunits, resulting in decreased protein synthesis in gastrointestinal mucosal cells.
60S
- small gram-negative (coccobacillary) rods
- requires factor X (hemin) and V (NAD) for growth (chocolate agar)
HAEMOPHILUS INFLUENZAE
o dissemination of meningococci into the bloodstream
o multiorgan disease, consumptive coagulopathy, petechial or purpuric rash (purpura fulminans)
Meningococcemia
NONE of the cephalosporins are active against the following:
• Enterococci
• Listeria monocytogenes
• MRSA
