Micro Block 2

  1. Straphylococci - General Characteristics
    • Genus: Straphylococcus
    • Gram Positive
    • Non Flagellated
    • Easily grown on most media
    • No Endospores
    • Facultative anaerobes
    • Some have Capsules; normal flora of skin
    • Pathogen: Straphylococcus aureus
  2. Straphylococcus aureus
    • Found in the nares of healthy people. (Nasal carriers) Autoinfections from nares and skin.
    • Nosocomial infections
    • Very resistant to drying
    • Now resistant to many antibiotics
    • coagulase + mannitol agar
  3. mannitol - salt agar is selective and differential
    • Selective - 7.5% NaCl
    • Differential - Staphylococcus aureus ferments mannitol. dye added which turns yellow in acid pH
  4. Bacteriophage
    virus of bacteria
  5. Bacteriophage (phage) Typing
    • Can be done in broth: no bacterial growth
    • Can be done on agar plate streked with bacteria: look for plaques
  6. Alpha Toxin
    • Straphlococcus aureus toxin
    • Partially destroys heme molecule. BAP green
    • Destroys WBCs, platelets - Necrosis
    • Punctures host cell membrane with leakage
  7. Pyrogenic (fever) exotoxins
    • toxic shock syndrome
    • fever, malaise, major organ damage
  8. Enterotoxins
    • Major cause of food poisoning (2-3 hours afer meal)
    • Nausea, vomiting, dizziness
    • usually lasts several hours
    • resistant to boiling and gastric pH
    • get from pyogenic lesion on foot handler
  9. Exfoliatins
    • exfoliates skin layers
    • *Stratum spinosum and stratum granulosum)
    • Scalding of skin of skin (shedding in layers)
  10. Coagulase
    fibrin clots formed protects bacteria from phagocytosis
  11. Toxins and enzymes of Straphylococcus (cont)
    Hemolysins, Haluronidase, Nucleases, Lipases, Proteases
  12. Virulence of Straphylococcus aureus
    • Teichoic acid in CW binds to host CM. Adhesion.
    • Usually there is low infectivity. Need trauma, foreign objects, etc.
    • Convict study:
    • 10^5- 10^6 intradermal bacteria required to cause infection.
    • If talcum powder is applied to skin, less than 100 cells cause infection (due to dry environment).
    • Surface protein A - helps the bacteria bind to host’s
    • cells
  13. Furuncle - SA
    boil. Deep pus filled lesion
  14. Carbuncle - SA
    a necrotic infection of skin and subcutaneous tissue composed of clusters of furuncles
  15. Pyogenic Lesions - SA
    pus, mainly on hands and feet
  16. scaled skin syndrome - SA
    • Intradermal splitting of epidermis between the stratum spinosum and stratum
    • granulosum
    • Caused by exfoliatin toxins.

  17. Toxic Shock Syndrome - SA
    • 1980s tampons
    • renal and liver damage
    • fever, vomiting, diarrhea, muscle pain, sore throat
    • many women have S. aureus in normal vagina flora
    • eradicated by making tampons allow air movement
  18. Food Poisoning - SA
    • Food preparer had S. aureus lesions on hands
    • Food not refrigerated (picnics)
    • potato salad and creamy dishes
    • acute vomiting and diarrhea usually within 2-3 hours
    • Prostration - collapse: an abrupt failure of function or complete physical exhaustion
    • recovery usually rapid
  19. Treatment for S. aureus
    • antibiotic susceptibility tests
    • proper antibiotic
    • drainage of pyogenic skin lesions
  20. prevention from S. aureus
    • Washing clothing and bedding with water above 70C
    • Wash skin with hexachlorophane soaps, etc.
    • Nasal creams with antibiotics
  21. diagnosis for S. aureus
    • gram stains of pyogenic lesions (gram +)
    • hemolysis on blood agar plate (BAP)
    • All straphylococci are catalase +
    • only S. aureus is coagulase +
    • Disc Sensitivity Test or antibiotic susceptibility test
  22. Staphylococcus epidermidis
    • Coagulase Negative
    • flora of skin, nares, ears, etc.
    • usually opportunisitic
    • now with catheters and prosthetic devices, they are important nosocomial infections (bladder infections)
    • Some strains secrete slime (similar to capsule) which help them adhere to host's cells
    • if on prosthetic device, the device must be removed
  23. Staphylococcus saprophyticus
    • coagulase negative
    • saprophyte - organism living on dead animals or vegetation found in environment
    • opportunist
    • uropathogen
  24. Coagulase negative bacteria
    • most are resistant to many antibiotoics (staphylococci)
    • do disc sensitivity test
  25. micrococci
    • commensals - living on an organism without harming it
    • free living
    • Gram positive
    • Aerobes - usually facultative, some obligate
    • Opportunist
    • includes: micrococcus, tetracoccus, sarcina (all coagulase negative and catalase positive)
    • pathogenesis - similar to coagulase negative staphylococci
  26. Streptococci
    • Gram Positive
    • Grow best on enriched media
    • Normal flora of oral cavity, nasopharynx, and GI tract
    • 1 micrometers
    • chains of 30 or so cells
    • non-acid fast, non-motile, some have capsules
    • grow best on blood agar. Look for type of hemolysis:
    • -alpha = green color. Partial lysis heme
    • -beta = clear color. Complete lysis heme
    • catalase negative
    • aerobic to facultative anaerobic
    • the obligative anaerobic streptococci are now placed in the genus peptostreptococcus
  27. Streptococcus pyogenes (Group A)
    acute infections that can cause rheumatic fever and acute glomerulonephritis
  28. Streptococcus agalactiae (Group B)
    neonatal sepsis and meningeal infections
  29. Streptococcus pnemoniae
    pnemonia and meningitis
  30. pyogenic streptococci
    • these have Lancefield antigens
    • Often cause purulent infections
    • often speciated by type of hemolysis and enzymes
    • most human pathogens: pyogenic groups A and B
  31. pnemonococci
    • only 1 species = S. pnemoniae
    • No Lancefield group antigens
    • unusual because it can be diplococcus
    • polysaccharide capsule
    • alpha hemolytic
    • 80+serotypes
  32. Veridans streptococci
    • No Lancefield antigens
    • alpha hemolytic
    • no casular antigens
    • normal oral flora
    • almost never pathogenic
    • several species: S. salivarius, S. mitis
  33. Others
    • Like viridans, but NOT hemolytic
    • assigned descriptive terms: non - hemolytic streptococci, microaerophilic streptococci
    • almost never pathogenic
  34. Pharyngitis
    • most are beta hemolytic
    • strept throat
    • obtained by droplet infection
    • group A streptococcal
  35. impetigo
    • skin infection. often co - infected with Staphylococcus
    • pinpoint blisters that are followed by dry scabs
    • usually associated with poor hygiene (orphanage)
    • obtained by direct contact or fomite
    • beta hemolytic
    • group A streptococcal
  36. Erysipelas
    • skin infection spreading into a red lesion with edema
    • associated with fever
    • obtained by direct contact or fomite
    • toxins released in blood could cause serious problems
    • beta hemolytic
    • group A streptococcal
  37. wound and burn infections
    • nosocomial
    • diffiucult to treat due to antibiotic resistance
    • pyogenic lesions present
    • must do antibiotic disc sensitivity tests
    • group A streptococcal
  38. Puerpearl infections
    • puerpera - women that has just parturated
    • infections enters mother following umbilical cutting
    • usually associated with home - births (midwife, etc.)
    • group A streptococcal
  39. Scarlet fever
    • focus is upper respiratory tract
    • toxins travel throughout body in blood
    • key diagnostic criteria: fever, scarlet red skin color, strawberry tongue
    • group A streptococcal
  40. toxic shock - like syndrome
    • symptoms are similar to staph toxic shock syndrome
    • obtained by droplet infection
    • toins spread from lungs to major organ systems (lethal)
    • super antigen
    • Group A streptococcal
  41. rheumatic fever
    • complication of pharyngitis (less than 1%)
    • cardiac failure usually cause of fatality
    • theories of infection process
    • 1. strept fragments attatch to cardiac muscle and antibodies are made which destroy cardiac muscle (autoimmune disease)
    • 2. Strept grow in throat and antibodies made which react with certain proteins in heart similar to strept. Antibodies destroy heart tissue
  42. acute glomerulonephritis
    • complication of pharyngitis (less than 1%)
    • several theories explain
    • sticking of antibodies glomerular basement membrame
    • two theories of infection process:
    • 1. antigenic strept fragments attach to glomerular basement membrane and antibodies are made which destroy this bm. Autoimmune disease
    • 2. strept grow in throat and antibodies made which react with certain proteins in kidney similar to strept. antibodies destroy glomerular bm
  43. lab diagnosis of Group A streptococci
    • throat swab on anaerobic BAP
    • beta hemolysis
    • identify Lancefield group by serology
    • Most are inhibited by bacitracin
    • use bactracin discs
  44. Group B streptococci
    • example is S. agalactiae
    • Leading cause of neonatal sepsis and meningitis
    • colonizes respiratory tract and associated with pyogenic infections at non - respiratory sites (skin)
    • Puerperal fevers
    • infections associated with surgery (prosthetics) or gynecological manipulations (IUD, etc.)
  45. Other pyogenic streptococci (non A or B)
    • occasionally produce respiratory, skin, wound, soft tissue, and genital infections that may resemble groups A & B
    • Bacteremia with S. bovis is associated with colon cancer
  46. streptochoccus pnemoniae
    • lancet - shaped gram + diplococcus (viral infection may have caused shape change) & streptococcus
    • virulent strains have capsule
    • alpha hemolytic
    • bile solubility test distinguishes S. pneumoniae from the alpha hemolytic veridans streptococci
  47. pnemococcal disease
    • MCC: bacterial pnemonia - mortality is high for people over 50 (and before antibiotics); many carriers
    • predisposing factors: alcoholism, diabetes mellitus, and renal diseases
    • huge capsule with many enzymes and toxins
    • 80+ serotypes
    • antibodies of S. pneumoniae cross react with capsule of Klebsiella pnemoniae & Haemophilus pnemoniae (both Gram - rods)
  48. Enterococci
    • Enterococcus faecalis
    • Lancefield group D antigens
    • Gram + streptococci (shape)
    • DNA homology studies now separate them from the streptococci (genus). Former name was Streptococcus faecalis
    • present in intestinal tract. Fecal contamination
    • Grow on ile and high salt
    • Many resistant to antibiotics
    • some are hemolytic; some are non - hemolytic
    • opportunistic
  49. Corynebacteria
    • facultative aerobes
    • no spores: not motile
    • catalase (+)
    • Gram positive, twisted rods
    • V or L shape
  50. diphteroids
    • missing viral - induced toxin genes
    • opportunists
    • commensals of pharynx, nasopharynx, distal urethra, skin
  51. corynebacterium diptheriae
    • selective media = tellurite (black colonies due to reduction of tellurite)
    • gram stains and test for enzymes
    • transmission: droplet infection, direct contact, fomites
    • convalescent pharyngeal or nasal carriers
    • mainly occurs now in developing tropical countries
  52. toxin development and release of Corynebacterium diptheriae
    • gene for toxin is contained in a lysogenic phage
    • many local and systemic effects of the toxin
    • inhibits protein synthesis and binds to CM of host cells
    • toxin is highly antigenic
    • diphtherioids missing viral - induced toxin genes
  53. corynebacteria rods
    • have a beaded appearance
    • beads - consist of granules of a highly polymerized phosphate that is a storage mechanism for high - energy phosphate bonds
    • granules stain metachromatically (dye that stains the rest of the cell blue will stain the granules red (methylene blue)
  54. clinical aspects of diphtheria
    • pharyngitis, malaise, fever
    • pseudomembrane (gray - white) - due to toxin activity acting like a strong acid, leaving gray - white scar tissue
    • bullneck - cervical nodes, adenoditis, edema
    • complications and lethal effects caused by respiratory obstruction or systemic effects of the toxin
    • toxin in the circulatory system will damage organs (heart, nervous, system)
    • organism remains in throat, toxins goes to blood, from there it can affect the skin causing pustules and lesions
  55. diagnosis of diphtheria
    • symptoms: pseudomembrane and bullneck
    • selective media: tellurite agar (patients coughs onto plate)
    • gram + twisted rods
    • enzymes: many - lactase, maltase, etc.
    • serology: antibody assays after 1 week
  56. treatment for diphtheria
    • antitoxin, which should be given immediately on the basis of clinical impression because there is a delay in laboratory diagnostic procedures
    • toxin binds rapidly to cells and can not be neutralized by antitoxin. function of antitoxin is to neutralize any unbound toxin in blood
    • because the antitoxin is made in the horse, the patient must be tested for hypersensitivity and medications for the treatment of serum sickness must be available
  57. prevention for diphtheria, pertussis, tetanus
    • immunization - DPT vaccine (contains diphtheria toxoid, tetanus toxoid, and acellular pertussis vaccine (purified protein from Bordetella pertussis))
    • immunized persons may become infected because their antibodies are against a toxoid. however their disease is mild
  58. Listeria monocytogenes
    • listeriosis
    • gram + rods (v or l shaped)
    • beta hemolytic
    • catalase (+)
    • facultative anaerobes
    • motile - moves by tumbling (corynebacteria are not motile)
    • widely spread among wild and domesticated animals
    • found in intestines
    • food - borne transmission (milk)
    • mostly obtained from unpasturized milk products
    • can grow at 4 degrees C and non-immune macrophages
    • enter macrophage by endocytosis
    • once inside cytoplasm of host cell, it stimulates the rearrangement of the host's actin fibers
    • pseudopods form in host cell with extension to adjacent cells with the spread of Listeria (actin rockets)
  59. clinical aspects of listeria monocytogenes
    • spread often by unpasturized milk or unwashed, raw vegetables grown in fields with animal fertilizer
    • symptoms mimic other diseases: meningitis, bacteremia, endocarditis, urethritis, conjunctivitis
    • high incidence in renal transplants. Causes meningitis and sepsis in newborns and immunosuppressed adults
    • carriers - many people highly immune
  60. listeria monocytogenes found in
    • may be found in the GI tract and female genital tract
    • transmission may be across placenta or by contact during parturition
    • outbreaks related to unpasturized milk or milk products (cheese)
  61. Erysipelas (erysipelothrix rhusiopathiae)
    • Gram+ rods
    • in animals and decaying matter
    • traumatic inoculation of mo into skin produces erysipeloid (red, painful, slow spreading erythematous swelling of the skin)
    • also caused by Group A Streptococcus
    • Occupational disease of fisthermen, butchers, veterinarians, and animal handlers
  62. Bacillus (streptobacillus)
    • Gram+ rods
    • spores (position used to speciate); aerobic
    • some are motile
    • most: saprophytes
  63. Bacillus anthracis
    • anthrax
    • Gram+ "bamboo rods" with square ends
    • Medusa colonies
    • glutamate capsule --> tendency to form chains
    • elliptical central spore
    • non-motile; non-hemolytic
  64. anthrax cont.
    • acquired through breaks in skin or mucous membranes; also through inhaling or ingesting
    • spread by spores in soil from animal feces
    • affected animals often develop fatal septicemic disease
    • occupational disease (goat handler)
    • pathogenesis: capsule & exotoxins
    • clinical: 2-5 incubation time; initial lesion is erythematous papule, "redness of the skin due to congestion of a capillary"
    • often mistaken for an insect bite
    • papule usually progresses through vesicular and ulcerative stages (7-10 days); form black eschar (scab) - lesion usually heals
    • less commonly - disease progresses with massive local edema, toxemia, bacteremia, and is fatal if untreated
  65. pulmonary anthrax (woolsorter's disease_
    • inhalation of spores from animal (sheep)
    • pnemonia - like disease
    • focus in lungs then spreads to body
  66. gastrointestinal form
    ingesting raw or undercooked meat containing spores
  67. laboratory diagnosis of anthrax
    • smears show large gram-positive rods in chains
    • spores usually not seen in smears of exudate
    • colonies form on BAP aerobically
    • not motile; but other bacilli are usualy motile
    • rise in antibody titer in agglutination test is diagnostic
    • treatment: penicillin G and other antibiotics are effective. strains usually not resistant to antibiotics
    • prevention: sterilizing dead animals and animal products from areas of endemic infections
    • people at risk can be immunized with cell-free vaccine
  68. Bacillus cereus
    • Gram+ rods
    • food poisoning
    • spores
    • opportunist
    • pyrogenic toxin causes food poisoning
    • survive steaming and rapid frying
    • spores germinate when rice is kept warm for many hours (re-heated fried rice)
    • clinical findings: short incubation period (3 hrs - nausea and vomiting and similar to staphylococcal food poisoning )
    • long incubation period (18 hrs - watery, non-bloody diarrhea and resembles clostridial gastroenteritis)
    • prevention: cooked rice should not be kept at room temperature or warm for long periods
  69. Anaerobes
    • lack cytochromes (use O2 as final electron acceptor)
    • lack catalase and peroxidases - enter body in mixed cultures
    • flora are usually harmles ->however, tissue devitalized by trauma, malignancy, etc -> life threatening
    • four groups: clostridium, bacteroides, fusobacterium, peptostreptococcus
  70. clostridium
    • gram+ rods
    • endospores
    • some are motile
    • found in soil with feces and in large intestines of animals
    • diseases: gas gangrene, tetanus, botulism, toxic enterocolitis
  71. bacteroides
    • gram- rods
    • no spores
    • pleomorphic
    • normal flora in the oral cavity and colon
  72. fusobacterium
    • gram- rods
    • fusiform shape
    • normal flora of oral cavity, colon and female genital tract. Abcesses of oral cavity and lesions of gums and pharynx
    • distinguished from bacteroides by metabolic end products. different enzymes
  73. peptostreptococcus
    • Gram+ streptococcus
    • normal flora of upper aliementary tract, upper respiratory tract and lower intestinal tract
    • rarely pathogenic
    • obligative anerobes (most strept. are facultative)
  74. clostridium perfringens
    • gram+ rods
    • non-motile; capsule
    • spores in soil; vegetative cells in colon and vagina
    • 4 major and 9 minor exotoxins
    • 5 serotypes based on toxins (A-E). Type A most impt.
  75. Type A - clostridium perfringens
    • food poisoning caused by exotoxin
    • alpha toxin = hydrolyzes lecithin and distrupts cell membrane; alpha hemolytic
    • beta toxin = alters capillary permeability and is toxic to cardiac muscle; beta hemolytic
    • 8-24 hour incubation
    • nausea, abdominal pain, diarrhea, rarely vomiting. Meat dishes (stews, gravy)
    • spores survive initial cooking
  76. anerobic cellulitis (Clostridium perfringens)
    • less virulent strains
    • wound infection with gas (H2S)
    • less severe than gas gangrene
  77. endometritis (Clostridium perfringens)
    unsanitary abortions
  78. Gas gangrene
    • C. perfringens, C. novyi, C. septicum -> species causing gas gangrene
    • acquire from deep wounds (spores) produces gas (H2S) with a putrid smelling leaking pus
    • Eventually tears open skin
    • treatment: minor surgery, antitoxin, antibiotics
  79. clostridium tetnais
    • gram+ rods
    • drumstick or tennis racket with terminal spores
    • motile
    • found in manured soil
    • large intestines of animals
    • neurotoxic exotixin (tetanospasmin) made by genes on plasmid
    • DPT vaccine (2,4,6,18 monts, 4 years)with booster every 10 years
    • diphtheria toxoid, pertussis pieces cells, tetanus toxoid
  80. Clostridium perfringens cont.
    • transmission: soil through wounds, injecting drugs, neo-natal tetanus - enters through a contaminated umbilicus or circumcision wound
    • pathogenesis: tetanus toxin (tetanospasmin) is an exotoxin (polypeptide) and produced by clostridium tetani at the wound site
    • toxin is carried to the CNS where it binds to ganglioside receptors and blocks the release of inhibitory mediators at spinal synapses
    • tetanus toxin and botulinum toxin are among the most toxic substances known; proteases that cleave proteins involved in mediator release
    • clinical: violent muscle spasms; lockjaw due to rigid contraction; facial grin known as "risus sardonicus"
    • exagerated reflexes, high mortality rate if untreated
  81. laboratory diagnosis/prevention of tetanus
    • lab diag: no good serologic test. organisms are seldum isolated from the wound site
    • tetanus is prevented by immunization with tetanus toxoid in childhood and every 10 years thereafter
    • when trauma occurs - wound should be cleaned and tetanus booster toxin given; wound is grossly contaminated, tetanus immune globulin, as well as the toxoid booster, should be given
  82. clostridium botulinum
    • botulism
    • gram+ rod with subterminal spore
    • several neurotoxins. all toxins are destroyed at 100C; resistent to enzymes and HCl in GI tract
    • toxins inhibit release of Ach at MEP- = muscle paralysis
    • production of toxin is determined by lysogenic phage and chromosomal genes
    • acidic canned foods
    • 18-96 hours incubation time; paralysis, dry mouth, constipation, urine retention
    • Treatment: antitoxin and antibiotics to patients with wound botulism
  83. botulism - transmission/pathogenesis
    • transmission - organism is carried in the GI tract of 3% of gp
    • 30% of hospitalized patients becoem colonized and this organism is, therefore, and important cause of nosocomial disease
    • transmitted by the fecal - oral route
    • pathogenesis: antibiotics supress drug - sensitive members of normal flora allowing clostridum difficile to multiply and produce exotoxins a and b
    • exotoxin a: enterotoxin that causes an outpouring of intestinal fluid resulting in watery diarrhea
    • exotoxin b: cytotoxin that causes damage to colonic mucosa, leading to pseudomembrane formation
  84. clinical findings - c difficile
    • causes diarrhea, associated with pseudomembranes (yellow-white plaques) on colonic mucosa
    • diarrhea is not usually bloody
    • neutrophils are found in stool in about half the cases
    • pseudomembranes are visualized by sigmoidoscopy
    • toxic megacolon can occur and surgical resection of the colon may be necessary
    • no vaccine
  85. bacteroides
    • anaerobic
    • gram- pleomorphic rods, non-spore forming
    • flora of mouth and colon
    • mcc of serious anaerobic infections
  86. bacteroides fragilis
    • most frequent anaerobe pathogen
    • infections often endogenous, usually arising from a break in a mucosal surface; non communicable
    • can cause a variety of infections such as local abscesses at the site of mucosal break and metastatic abscesses by spread of distant organs
  87. facultative aerobes
    • E.coli
    • utilize the oxygen and contribute to the growth of this anaerobe
  88. clinical findings - bacteroides
    intra-abdominal infections - either peritonitis or localized abscesses; pelvic abscesses and bacteremia also occur
  89. bacteroides melaninogenicus
    • oral, pharyngeal, and pulmonary abscesses are more commonly caused
    • member of the normal oral flora
    • causes disease above the diaphragm
  90. bacteroides fragilis
    cause disease below the diaphragm
  91. lab diagnosis of bacteroides
    • can be isolated anaerobically on BAP containing kanamycin and vancomycin to inhibit unwanted mo
    • identified by biochemical reacitons and by the production of certain organic acids which are identified by gas chromatography
    • no vaccine
    • diagnosis can be confirmed on th ebasis of sugar fermentation tests: meningococci ferment maltose, whereas gonococci do not (both germent glucose)
    • bacteroides melaninogenicus - produces characteristic black colonies
  92. Neisseria
    • gram- diplococci
    • resemble paired kidney beans
    • non-motile
    • usually capsules & fimbriae
    • grows best with CO2 and blood (fastidius)
    • Oxidase+
    • phagocytosed by neutrophils
  93. neisseria meningitidis
    • Meningitis and Meningococcemia
    • bap enhanced with CO2
    • capsule antigens divide into serotypes. vaccines for most of these serotypes
    • respiratory droplets: humans are the only natural hosts
    • nasal carriers (5-15%)
    • attaches to non-ciliated columnar ET of host upper respiratory tract by fimbriae
    • IgA protease (destroys IgA (gamma globulin fraction))
    • enters meninges by blood stream
    • diagnosis: spinal tap L4-L5
    • Treatment: massive doses of antibiotics get into cns
  94. waterhouse-friderichsen syndrome
    • characterized by high fever, shock, wide-spread purpura (a small hemorrhage in the skin, mucous membrane, or serosal surface)
    • disseminated intravascular coagulation and adrenal insufficiency
  95. prevention of mengitis and meningococcemia
    • chemoprophylaxis and immunization are both used to prevent meningococcal disease
    • rifampin is used for prophylaxis because it is secreted in saliva
    • meningococcal vaccine, contains capsular polysaccharides of groups A,C,Y, and W-135 strains is effective in preventing epidemics and reducing the carrier rate
    • vaccien does not contain gropu B polysaccharide, which is poorly antigenic in humans
  96. immunofluorescence
    • used to identify species of Neisseria
    • procedure that can assist in the rapid diagnosis of meningococcal meningitis is the latex agglutination test -> detects capsular polysaccharide in the spinal fluid
  97. Neisseria gonorrhoeae
    • Gonorrhea
    • chocolate agar (heated blood) with CO2
    • very high in teenagers (asymptomatic females about 50% due to urethra size)
    • not normal flora -> sometimes in throat or rectum
    • diagnosis: symptoms (males): 2-7 days purulent urethral discharge with dysuria
    • gram- diplococci inside neutrophils
    • test for enzymes, e.g. sugar fermentation. no good serological test
  98. thayer - martin agar
    • agar containing a variety of antibiotics
    • chocolate agar
    • incubated at 37C
    • finding of oxidase - positive colonies composed of gram negative diplococci is sufficient to diagnose Neisseria
    • can use ELISA (detects antigens) or DNA probe assay (detects gonococcal ribosomal genes)
    • no vaccine. usual serological tests are not useful
  99. other neisseria
    • normal flora of the oral cavity and upper respiratory tract
    • do not grow on thayer-martin agar
  100. enterobacteriaceae (family) "enterics"
    escherichia coli, shigella, salmonella, yersinia, serratia, citrobacter, klebsiella, enterobacter, proteus, providencia, morganella
  101. enterics
    • all gram- rods
    • most in large intestines
    • aerobic to anerobic
    • no spores
    • some cause diarrhea
  102. E.coli
    • mcc of urinary tract infections
    • when get into blood, may cause sepsis
    • may have fimbraie
    • some have capsules
    • most secrete slime
    • Habitat: L1, female genital tract, some may be in upper respiratory tract, some can be free-living
    • all possess LPS toxin and usually many other toxins
    • divided into strains (instead of species) based on antigens present in CW, capsule, and flagella
  103. antigens for ecoli
    • o antigens - cw lipopollysaccharide (LPS)
    • a antigens - CW lipid
    • k antigens - capsules
    • h antigens - flagella
    • O111:H7 - very virulent (uremic toxemia - renal failure)
    • -->urinary tract infections, intestinal tract infection (diarrhea), meningitis (neonatal)
    • O18:K76
    • 150+ types based on antigens
    • ferments lactose -->EMB agar
  104. classification of enterobacteriaceae
    • cultural characteristics (colony size, shape, color, etc.)
    • biochemistry: all ferment glucose, reduce nitrates, oxidase negative
    • they differ in: carbohydrate fermentations, SIM test
    • antigens (O,A,K,H)
  105. shiegella (shigellosis)
    • do not ferment lactose
    • no H2S gas
    • non-motile, speciate with antigens and biochemistry
  106. shigella sonnei
    • usa under 10 years
    • fecal contaminatio: dysentery (shiegella flexneri, boydii, and dysenteriae), bloody diarrhea, acute inflammatory colitis
    • plasmids were first discovered in this
  107. salmonella (salmonellosis - all except typhi)
    • do not ferment lactose
    • release H2S gas
    • Enterocolitis & Septicemia
    • ubiquitous in animals. usually acquired by fecal contamination of man and animals (chicken) - gastroenteritis
  108. salmonella typhi
    • typhoid fever
    • gastroenteritis and enteric fever
    • tests: stool culture on EMB agar or deoxycholate
  109. yersinia
    • gram- bipolar staining
    • mainly an animal parasite
  110. yersinia pestis
    • causes the plague
    • enters dermal lymphatics by flea bites
    • zoonosis
  111. Y. enterocolitica and Y. pseudotuberculosis
    • invades mesenteric lymphatics (peyer's patches)
    • do not possess the virulence factors of Yersinia pestis
    • transmitted to humans by contamination of food with the excreta of domestic animals (dogs, cats, cattle)
    • can cause mesenteric adentis that clinically resembles acute appendicitis; rarely they are involved in bacteremia or abscesses of the liver and spleen
    • enterocolitica - clinically indistinguishalbe from that caused by salmonella or shigella
  112. serratia
    • slowly ferment lactose
    • inducible enzymes
    • opportunist - diarrhea
    • nosocomial infections
    • resistant
  113. citrobacter
    • biochemically and serologically similar to salmonella, but usually does NOT cause enterocolitis or enteric fever
    • maybe present in normal intestinal flora
    • opportunist and may cause diarrhea
    • can use citrate as sole source of carbon
  114. klebsiella
    • severe pnemonia & URT infections
    • polysaccharide capsule and non-motile
    • over 70 types based on capsule possess fimbriae
  115. klebsiella pnemoniae
    • lobar pnemonia and is now resistant to many antibiotics
    • grows in lungs (not GI)
  116. Enterobacter
    • mild pnemonia
    • ferment lactose
    • peritrichous flagella
    • less virulent than Klebsiella pnemoniae (mild pnemonia)
    • usually found in mixed infections
    • now resistant to many antibiotics
  117. aids patients only
    • proteus (p. vulgaris)
    • providencia
    • morganella
  118. Vibrios
    • gram-
    • often polar flagella
    • chains of coma shaped rods - streptobacilli
    • marine habitat - tolerate SALT (halophilic)
    • most infections are due to penetrating wounds (fish hook)
  119. vibrio cholerae
    • cholera
    • speciated by: o antigens, biochemistry, enterotoxins
    • usually acquired by fecal contamination
    • rice water stool (rice substance is GI epithelial cells)
    • vaccines. carriers.
    • no abdominal pain and subsequent symptoms are referable to the marked dehydration -> loss of fluid and electrolytes may lead to cardiac and renal failure
    • acidosis and hypokalemia
  120. vibrio parahaemolyticus
    • marine organism transmitted by contaminated seafood
    • major cause of diarrhea in japan
    • varies from mild to severe watery diarrhea, nausea and vomiting, abdominal cramps and fever
    • lasts about 3 days
    • can be prevented by proper refrigeration and cooking of seafood
  121. vibrio vulnificus
    • found in seawater
    • caues severe skin and soft tissue infections (cellulitis), especially in shellfish handlers thru skin wounds
    • also cause a rapid fatal septicemia of AIDS patients who have eaten raw shellfish containing the organism
    • chronic liver diseases (cirrhosis) predisposes to severe infection
  122. other vibrios
    • halophilic
    • often enter thru cuts in marine environment
    • diarrhea and cramps
  123. campylobacter
    • curved gram- rods
    • polar flagella
    • oxidase(+) & microaerophilic. Urease negative
    • normal flora of GI and UG tract flora of animals (cows, sheep, birds, dogs)
    • frequent cause of enterocolitis, especially in children, and a rare cause of systemic infection, particularly bacteremia
    • transmission: by fecal - oral route
  124. C. jejuni & C. enteritis
    • diarrhea
    • C. jejuni - begins as watery foul-smelling diarrhea followed by bloody stools accompanied by fever and severe abdominal pains
  125. C. fetus
    • abotion in animals - due to toxin coating fetus causing the immune system to turn on it, abortion ensures
    • sepsis in humans
  126. Campylobacter intestinalis
    • systemic infections, most commonly bacteremia
    • lab diagnosis: patient has diarrhea, a stool specimen is cultured on a blood agar plate containing antibiotics to inhibit other fecal flora
    • no vaccine. proper sewage disposal and personal hygiene (hand washing) are important in preventing the disease
  127. Helicobacter
    • curved gram- rods
    • peptic ulcers and gastritis
    • urease +
    • helicobacter pylori
  128. H. Pylori - pathogenesis and epidemiology
    • attaches to mucus secreting cells of gastric mucosa
    • production of large amounts of amonia from urea by organism's urease, coupled with an inflammatory response, leads to damage of the mucosa
    • loss of protective mucus coating predisposes to gastritis and peptic ulcer -> ammonia neutralizes stomach acid, allowing mo to survive
    • natural habitat of H. pylori is human stomach, acquired by ingestion; person to person transmission probably occurs
  129. H.pylori - lab dagnosis/treatment&prevention
    • lab diagnosis: gram stained smears of biopsy specimens of gastric mucosa
    • cultured on special media. presence of IgG antibodies can be used as evidence of infection
    • "urease breath" test, in which radioactive urea is ingested, can also be used
    • if mo is present, radioactive carbon dioxide is evolved and detected in the breath
    • treatment and prevention: treatment of duodenal ulcers with antibodies and bismuth salts (pepto-bismol) results in greatly decreased occurence rate
    • no vaccine
  130. pseudomonas
    • gram- rods - resemble enterobacteriacae, but differ in that they are strict aerobes
    • do not ferment glucose
    • oxidase positive (oxidation involves electron transport by cytochorme C)
    • able to grow in water containing only trace nutrients e.g. tap water
    • favors their persistence in the hospital environment
    • some withstand disinfectants
  131. pseudomonas aeruginosa
    • gram- rod
    • aerobic, motile, opportunist (wound, tube, etc)
    • water soluble greenish pigment
    • pathogen of plant and animals
    • most commonly found in humans: burns, cystic fibrosis, aids, and catheterizations
    • treatment: swab lesion -> culture -> test for enzymes
  132. p. aeruginosa - pathogenesis and epidemiology
    • found in soil and water
    • colon flora - found on skin in moist areas and can colonize the URT of hospital patients
    • ability to grow in simple aqueous solutions has resulted in contamination of respiratory therapy and anesthesia equipment, intravenous fluids, and even tap water
    • opportunist, exotoxin and endotoxin play roles in pathogenesis
    • two pigments: pyocyanin and fluroescein are non toxic
  133. clinical findings in P. aeruginosa
    • cause infectious virtually anywhere in the body but urinary tract infections, wound infections and burns predominate
    • can enter blood and cause sepsis
    • can spread to skin where causes black, necrotic lesions
    • corneal infections are seen in contact lens users
  134. haemophilus
    • gram- coccobacilli
    • non-motile
    • some have capsules
    • most have fimbriae
  135. haemophillus influenzae
    • needs complex lab media containing hematin (factor X) and NAD (factor V)
    • vaccines
    • spreads by droplet infection (epidemic WWI)
    • respiratory transmission, meningitis is most common type of infection with brian damage and middle ear infections.
    • epiglottiditis, cellulitis, arthritis, and varied respiratory tract infections
  136. pathogenesis and epidemiology of influenzae
    • infects only humans and no animal reservoirs
    • enters body through URT, resulting in asymptomatic colonization or infections such as otitis media, sinusitis, or pnemonia
    • organism produces IgA protease that degrades IgA, thus facilitaing attachment to respiratory mucosa
    • URT may spread via blood to meninges -> meningitis is primarily caused by the encapsulated strains
    • most infections occur in children between the ages of 6 mts to 1 yr
  137. lab diagnosis of influenzae
    • chocolate agar enriched with factor X (heme) and factor V (NAD)
    • biochemical tests
    • Quellung test, flurescent antibody tests, agglutination tests
  138. clinical findings of influenzae
    • cannot be distinguished on clinical grounds from that caused by other bacterial pathogens (pnemonococci or meningococci)
    • rapid onset of fever, headache, stiff neck, and drowsiness
    • sinusitis and otitis media cause pain in the infected area
    • rarely, epiglottis can obstruct the airway
  139. Bordetella pertussis
    • whooping cough or pertussis
    • strict human pvaccine athogen
    • incubation 7-10 days
    • catarrhal stage (inflammation of mucous membranes), paroxysmal cough (spasm), convalescence
    • Nasal swab on charcoal (cocolate) blood agar fluorescent antibody serology
    • DPT
  140. mycoplasma
    • PPLO - pleura pnemonia0like organism
    • no cell wall
    • gram-, but stain poorly
    • .2 micrometers (smallest cell)
    • pleomorphic
    • sterols in cm acquired from media (the mo does not make sterols)
    • aerobic to facultative anaerobic (species dependent)
  141. mycoplasma pnemoniae
    • fried egg colonies
    • 20% of pnemonia
    • droplet infection
    • very low infectious dose
    • attaches to bronchial ET via cytadhesion protein in its cytoplasmic membrane
    • grow on mycoplasma agar
  142. serology
    flluorescent antibody test more sensitive
  143. mycoplasma hominis
    • flora of genitourinary tract
    • post - abortion and post - partum infections
    • disease is usually self limiting
    • other mycoplasmae often found in arthritis
  144. ureaplasma
    • gram-, but stain poorly
    • no cell wall
    • .2 micrometers
    • pleomorphic
    • sterols in CM
    • urease + (mycoplasma are urease -) salts ppt in urine
    • Only 1 species: Ureaplasma urealyticum
  145. Ureaplasma urealyticum
    • female genital tract
    • sexually transmitted
    • no sterility
    • itching
    • non - gonococcal, non -chlamydial urethritis
  146. Legionella
    • 30+ species
    • Thin (.2 micrometer), pleomorphic
    • gram- rod
    • 2-20 micrometer long
    • stains poorly with Gram reagents
    • use silver impregnation stains (coats the rods, blackish)
    • most have flagella
    • no spores
    • aerobic
  147. Legionella pnemophillia
    • Legionellosis or Legionnaries disease
    • fastidius (requires L-cysteine and Fe+3)
    • colonies resemble "ground glass"
    • found in fresh water, soil; parasite of protozoa (amoeba)
    • cases - linked to water habitat: hotel cooling towers for air conditioners, respiratory devices, tap water
    • person to person spread not shown
    • attacks the lungs: necrotizing multifocal pnemonia
    • 2 syndromes: legionnaires' disease (severe pnemonia) and Pontiac fever (non-pnemonia, febrile, not life threatening)
    • fluroescent antibody tests
  148. clinical findings - Legionella pnemophillia
    • clinical picture can vary from a mild influenza - like illness to a severe pnemonia accompanied by mental confusion acompanied by mental confusion, non-bloody diarrhea, proteinuria, and hematuria
    • sputum is frequently scanty and non-purulent - cough is prominent
    • spontaneously in 7-10 days, but in older or immunocompromised patients the infection may be fetal
  149. Moraxella
    Gram- cocobacillary rod
  150. Moraxella catarrhalis
    • major pathogen
    • member of normal flora of upper respiratory tract
    • causes sinusitis, otitis, bronchitis, and pneumonia - especially in immunocompromised patients
  151. Moraexella nonliqufaciens and Staphylococcus aureus
    two common causes of blephartitis (infection of eyelid)
  152. spirochetes
    • flexible, peptidoglycan CW with axial fibril (proteins)
    • motile; slim (.15 micrometers)
    • Dark field m.s. or e.m.
    • Gram negative -> too thin to visualize with conventional compound light microscope
    • normal flora of mouth
  153. treponema pallidum
    • syphilis
    • grows in lab by special tissue culture or on skin, cornea, or testes of rabbit
    • acquired: sexual contact, lesions, drug user needles
  154. neonatal syphilis
    • permanent scar tissue on skin
    • Hutchinson's teeth (affects tooth bud)
    • multiple effects on eyes, organs
    • exclusive human pathogen
  155. Syphilis con't
    • 3 stages:
    • Primary: 2-10 weeks; Hard chancre (haemophilus ducreyi -soft chancre "chancroids); heals in 3-8 weeks; Silent 2-10 weeks
    • Secondary:
Card Set
Micro Block 2
Block 2 Exams