MPH 570

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MPH 570

• Microbiology 1
• Bacteriology
• Professor Kenneth L. Elkins
• Cleveland Chiropractic College

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Microbiology

• Definitions
• 1. The Study of living organisms which are not
  visible with the unaided eye
• 2. The study of microorganisms and viruses

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Microbiology

• Scope
• 1. Organism Types
• a. bacteria
• b. fungi unicellular and multi cellular
  filamentous eucaryotic organisms which produce
  both sexually and asexually.
• c. protozoa
• d. metazoa
• e. viruses
• 2. Immunobiology
• 3. Biochemistry
• 4. Molecular Biology/Genetics
• 5. Epidemiology

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Microbiology

• History
• 1. Louis Pasteur
• 2. Robert Koch
• 3. Joseph Lister
• 4. Antonie van Leeuwenhoek
• 5. August Semmelweis
• 6. D. Ivanovski
• 7. Paul Ehrlich

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Koch Postulates

• 1. The organism must be found in every case of
  the disease or illness
• 2. The organism must be obtained or isolated in
  pure culture
• 3. The organism must be maintained and
  subcultured in the laboratory for a defined
  period of time
• 4. The organism must be re-introduced into a
  susceptible host and the original disease must
  develop in that host.

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Taxonomy

• Superkingdom
• 1. Procaryotae
• 2. Eucaryotae
• Kingdom
• 1. Monera
• 2. Protista
• 3. Mycota(Fungi)
• 4. Animaliae
• 5. Plantae
• Genus
• Species

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Procaryotic Cell

• Bacteria
• Definition- unicellular procaryotic cells which
  exhibit extensive metabolic diversity
• Shapes
• 1. cocci
• 2. bacilli
• 3. spirochetes
• 4. spirilla
• Sizes

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Procayotic Cell

• Cell Structures
• 1. cytoplasmic membrane
• 2. cell wall
• 3. glycocalyx
• a. capsule
• b. slime layer
• 4. fimbriae/pili
• 5. flagella
• 6. nucleoid
• 7. ribosomes
• 8. inclusion bodies
• 9. endospores

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Gram vs. Gram - Cells

• Gram positive Cell
• cytoplasmic membrane
• peptidoglycan
• teichoic acids
• proteins
• Gram negative Cell
• cytoplasmic membrane
• peptidoglycan
• periplasmic space
• outer membrane
• core antigen
• somatic antigen
• LPS

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Bacterial Classification

• 1. By phenotypic characteristics
• a. morphology
• b. biotyping
• c. serotyping
• d. antibiograms
• e. pyocins
• f. phage
• 2. By genotypic characteristics
• a. guanine plus cytosine ratio
• b. DNA hybridization
• c. nucleic acid sequence analysis
• d. plasmid analysis
• 3. By analytic characteristics

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Bacterial Classification

• 1. Aerobic, Gram-positive cocci
• a. catalase-positive
• b. catalase-negative
• 2. Aerobic, Gram-positive bacilli
• a. with cell wall mycolic acids
• b. with no cell wall mycolic acids
• c. misc gram-positive bacilli
• 3. Aerobic, Gram-negative cocci and bacilli
• a. cocci
• b. bacilli
• 4. Anaerobic Gram-positive and Gram-negative
  bacteria
• a. gram-positive cocci
• b. gram-positive bacill
• c. gram-negative cocci
• d. gram-negative bacilli
• 5. Misc Medically Important Bacteria

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Bacterial Metabolism

• Intermediary Metabolism
• 1. Anabolism
• 2 Catabolism
• Metabolic Pathways
• 1. Glycoysis Embdem-Meyerhof-Parnas
• substrate-level phosphorylation
• fermentation
• anaerobic
• final acceptor of electrons is an organic
  substance
• 2. Tricarboxylic Acid CycleKrebs
• oxidative phosphorylation/electron transport
• aerobic respiration
• final acceptor of electors is oxygen
• amphibolic
• 3. Pentose Phosphate Shunt
• energy and precursors for biosynthesis
• 4. Other
• anaerobic respiration

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Bacterial Metabolism

• Growth Conditions
• 1. presence or absence of oxygen
• obligate/facultative aerobes
• obligate/facultative anaerobes
• 2. temperature
• psychrophiles
• mesophiles
• thermophiles
• 3. pH
• 4. osmotic pressure
• Requirements for growth and metabolism
• 1. carbon source
• 2. nitrogen source
• 3. energy source
• 4. water
• 5. specific ions

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Bacterial Genetics

• 1. DNA
• Nucleotide bases adenine, cytosine, guanine,
  thymine
• Nucleotide base pairs Ex. E. coli 5000
  kilobase pairs
• Genes nucleotide sequences that have a biological
  function
• Operons groups of structural genes regulated by a
  promotor/operator
• Haploid vs Diploid bacterial cells possess only
  one copy of a gene
• 2. Replication of Dna
• initiation site OriC
• enzymes
• primase
• helicase
• DNA dependent DNA polymerase 5 to 3 direction
• semiconservative replication
• leading strand
• lagging strand
• okazaki fragments
• DNA ligase

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Bacterial Genetics

• 1. Mutation
• transition replace one purine with another
  purine
• transversion replace a purine with a pyrimidine
• silent mutation no change in encoded amino acid
• missense mutation results in a different amino
  acid inserted
• nonsense mutation stops the reading of the m-RNA
• frameshift deletion or insertion which changes
  all codons
• null mutation complete destruction of gene
  function
• 2. DNA Repair mechanisms
• direct DNA repair
• excision repair
• 3. Genetic Exchange in bacteria
• a. transformation uptake of ds DNA from the
  growth environment
• b. conjugation transfer of DNA via sex pili F
  to F-
• c. transduction transfer of DNA via
  bacteriophages(viruses)

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Host-Microbe Interaction

• Symbiosis
• commensalism
• microflora
• mutualism
• microflora
• benefits
• parasitism
• pathogen
• virulence
• virulence factors
• infection
• disease
• colonization
• status a birth
• sterile areas
• opportunist

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Bacterial Pathogenesis

• Virulence
• genetic traits which enhance the abiltiy of a
  microbe to cause disease
• the degree of pathogenicity
• Portal of entry
• Infectious(inoculum) dose
• Infection
• the entrance, establishment, and multiplication
  of a microorganism within the tissues
• Virulence outcome
• destruction of host tissues
• release of toxins
• Basis of Symptoms
• the tissue which is affects
• the mechanism of a toxin
• host immune response

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Bacterial Pathogenesis

• Bacteria Virulence Mechanisms
• adherence
• invasion
• metabolic by-products
• degradative enzymes
• exotoxins
• A-B toxins
• genetic control
• target cell receptor
• biological effect
• endotoxin
• superantigen
• induction of excess inflammation
• evasion of phagocytic and immune clearance
• resistance to antibiotics

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Bacterial Pathogenesis

• Endotoxin-Mediated Toxicity
• fever
• leukopenia followed by leukocytosis
• activation of complement
• thrombocytopenia
• disseminated intravascular coagulation
• decreased peripheral circulation and perfusion to
  major organs
• shock
• death

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Gram-Positive Cocci

• Staphylococci
• division in more than one planeclusters
• catalase-positive
• facultative anaerobe
• osmophile
• mesophile
• microflora of skin and mucous membranes
• major opportuntist is Staphylococcus aureus
• coagulase-positive
• Streptococci and Enterococci
• division in one plane pairs and short chains
• catalase-negative
• most are facultative anaerobes
• ferment carbohydrates to lactic acid
• grouped by cell wall C-carbohydrate
• hemolytic

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Staphylococcus and related organisms

• Staphylococcus aureus
• most virulence opportunistic coccus
• basis of virulence
• capsule
• inhibits chemotaxis and phagocytosis
• facilitates adherence
• peptidoglycan
• stimulate release of endogenous pyrogens
• activates interleukin-1
• attracts PMN
• activates complement
• protein A
• binds the Fc receptor of IgG
• prevents antibody-mediated immunity
• teichoic acids
• mediate adherence to mucosal surfaces
• hapten when bound to peptidoglycan

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Staphylococcus aureus

• Basis of Virulence
• Structural components(previous slide)
• Toxins
• cytotoxins membrane-damaging toxins(5)
  necrosis, abcess
• alpha toxin - inserts into hydrophobic region
  altering membrane integrity
• beta toxin - hydrolyzes membrane phospholipids
• delta toxin - detergent-like action on cellular
  membranes
• gamma toxin - mode of action not defined
• leukocidin damages leukocytes thus resisting
  phagocytosis
• exotoxins
• exfoliative toxin(2) - serine proteases split
  desmosomes in epidermis
• toxic shock syndrome toxin -1 - superantigen
  causing cytokine release
• enterotoxins(5)-

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Staphylococcus aureus

• Basis of Virulence
• Enzymes
• coagulase secreted - catalyzes conversion of
  fibrinogen to fibrin
• clumping factor cell bound- catalyzes conversion
  of fibrinogen to fibrin
• catalase converts toxic hydrogen peroxide to
  water and oxygen
• hyaluronidase spreading factor - hydrolyzed
  hyaluronic acid
• fibrinolysin(staphylokinase) - dissolves fibrin
  clots activates plasminogen
• lipases - hydrolyzes lipids in the skin -
  nutritive function
• nucleases - hydrolyzes nucleic acids - nutritive
  function
• penicillinase - breaks the bet-lactam ring of
  penicllins inactivation

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Staphylococcus aureus

• Staphylococcal diseases
• pyoderma pyogenesis in the integument(skin)
• impetigo - multiple pustules with erythematous
  base on face and extremities
• furuncles - large, painful, nodules filled with
  pus and necrotic tissue boil
• carbuncles - multiple boils which coalesce in
  deep subcutaneous tissue
• wound infections - erythrema, edema, pain
  in/around wounds
• bacteremia - bacteria in the blood from other
  infections sites
• osteomyelitis - infection of highly vascularized
  area of bone
• endocarditis - infection of the endocardium
• toxic shock syndrome
• scalded skin syndrome
• food poisoning
• intoxication
• pneumonia - response to the presence of bacteria
  in the lungs

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Staphylococi

• Epidemiology/Control
• Reservoir/Source
• Transmission
• direct contact
• fomites
• food
• hematogenous
• Who is at Risk?
• Modes of Control
• Geography/Season
• Treatment

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Streptococci

• Streptococcus pyogenes
• streptococcal group A
• catalase negative
• bacitracin sensitive
• beta hemolytic
• Streptococcus agalactiae
• streptococcal group B
• catalase negative
• bacitracin resistant
• beta hemolytic
• osmophilic(variable)
• Streptococcus pneumoniae Streptococcus viridians
• no-group C-carbohydrate no C-carbohydrate
• catalase negative catalase negative
• bacitracin resistant bacitracin resistant
• optochin sensitive optochin resistant
• bile sensitive bile resistant

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Streptococcus pyogenes

• Basis of Virulence
• capsule antiphagocytic, nonimmunogenic
• M-protein antiphagocytic, degrades C3b
• M-like proteins binds to Fc region of IgG/IgM
• F-protein mediated adherence to epithelial cells
• pyrogenic exotoxins many effects(see table 23-4)
• streptolyin S lyses RBC/WBC,platelets,
  nonimmunogenic
• streptolysin O releases lysosomal enzymes,
  immunogenic
• streptokinase lyses blood clots(plasminogen
  activator)
• DNase depolymerizes cell-free DNA
• C5a peptidase degrade C5a

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Streptococcus pyogenes

• Group A Streptococcal Diseases
• pharyngitis - suppurative erythematous
  inflammation of the pharynx
• sore throat with exudate and cervical
  lymphadenopathy
• accompanied by fever, malaise and headache
• also known as strep throat
• scarlet fever - pharyngitis with diffuse
  erythematous rash on head/extrem
• rash blanches when pressed, raw red tongue
  strawberry tongue
• no rash around mouth or palms/soles
• pyoderma - purulent(pus forming) lesions on face,
  arms, and legs
• vesicles fill with pus, rupture, and crust over
• erysipelas - acute infection of the skin with
  fever, chills, leukocytosis
• inflamed areas is distinctly raised from
  uninfected skin
• cellulitis - localized inflammation of
  subcutaneous tissues
• accompanied by fever, chills, leukocytosis

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Streptococcus pyogenes

• Group A Streptococcal Diseases
• necrotizing fasciitis - infection of deep
  subcutaneous tissues
• extensive destruction muscle(gangrene) and fat
• spreads along facial planes
• often results in systemic toxicity, organ
  failure, and death
• streptococcal toxic shock syndrome multi system
  toxicity
• begins with localized soft tissue inflammation
  and pain
• accompanied by fever, chills, malaise, vomitting,
  diarrhea
• toxicity causes liver, heart, and lungs to fail
• patient is bacteremic and often has necrotizing
  faciitis
• bacteremia - beta hemolytic streptococci in the
  blood
• accompanies necrotizing faciitis and toxic shock
  syndrome
• does not occur with pharyngitis, pyoderma, or
  erysipelas
• rheumatic fever - nonsuppurative sequalae to
  group A Strep infection
• inflammatory changes in heart, joints, blood
  vessels, and subcutaneous
• chronic progressive damage to the heart valves
  often occurs
• glomerulonephritis - nonsuppurative sequalae to
  group A Strep infection
• acute inflammation of glomeruli
• accompanied by edema, hypertension, hematuria,
  and proteinuria

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Streptococcus pyogenes

• Diagnosis of Streptococcal Diseases
• Symptoms
• pharyngitis - with or without tonsillar exudate
• fever, rash, inflammation or swelling
• Laboratory Tests
• gram stain from specimen or culture
• culture
• bacitracin sensitivity
• hemolysis
• serology
• antigen detection(microantigen)
• detect group specific C-carbohydrate in throat
  cultures
• react antigen with antibody bound to membrane or
  latex particles
• antibody detection
• anti-streptolysin O (ASO test) indicates recent(
  3-4 wks) streptococcal infection and helps
  confirm rheumatic fever or acute
  glomerulonephritis
• anti-DNase B - helps confirm pyoderma or
  pharyngitis associated with glomerulonephritis

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Streptococcus agalactiae

• Basis of Virulence
• Capsule
• type-specific capsular polysaccharides I - VI
• antiphagocytic
• basis of serotypes
• Protein c
• antiphagocytic
• basis of serotypes
• hyaluronidase
• neuraminidase
• protease
• DNase
• hippurase
• hemolysins

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Streptococcal agalactiae

• Group B Streptococcal Diseases
• neonatal infections
• early onset bacteremia, pneumonia or meningitis
• perinatal exposure
• symptoms appear during first week
• neurological sequelae
• late-onset bacteremia with meningitis
• postnatal exposure
• symptoms appear after one week to as long as 3
  months
• neurological sequelae
• postpartum sepsis(puerperal sepsis)
• infection of incisions or postpartum uterus
• pregnancy
• urinary tract infection, amnionitis,
  endometritis, wound infection
• elderly immunocompromised adults
• diabetes mellitis, cancer, alcoholism
• skin and soft tissue infections, bacteremia,
  urosepsis, pneumonia

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Streptococcus pneumoniae

• Basis of Virulence
• Capsule
• complex polysaccharide capsule
• highly antiphagocytic
• basis of 90 serotypes
• used in pneumococcal vaccine
• c-substance ?
• exposed surface teichoic acids
• species-specific
• precipitates C-reactive protein(a serum
  globulinCRP
• surface protein adhesin
• pneumolysin
• secretory IgA protease

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Streptococcus pneumoniae

• Pneumococcal Diseases
• bacterial(pneumoncoccal) pneumonia
• lobar pneumonia
• bronchopneumonia
• sinusitis
• otitis media
• meningitis
• bacteremia

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Streptococcus pneumoniae

• Diagnosis of pneumococcal diseases
• gram stain
• sputum or lung aspirate, cerebrospinal fluid
• quellung reaction
• antigen detection
• pneumococcal capsular polysaccharide
• latex agglutination
• counterimmunoelectrophoresis
• culture
• alpha hemolysis
• optochin sensitive
• bile soluble

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Enterococcus and other gram-positive cocci

• Enterococcus faecalis/faecium
• Characteristics
• gram positive cocci phenotypically similar to
  Streptococci
• catalase negative
• facultaive anaerobes
• mesophiles with 35 C optimum temperature
• typically non-hemolytic, but may exhibit alpha or
  beta patterns
• osmophilic - grow well at 6.5 NaCl equalivent
• tolerates 40 bile and hydrolzyes esculin
• Basic of Virulence
• colonization factors(adhesins)
• secreted factors
• Infections/Diseases causes by Enterococci
• Laboratory Diagnosis
• Epidemiology

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Streptococcal diseaes

• Epidemiology, Prevention and Treatment
• Streptococcus pyogenes
• person-to-person, direct, respiratory droplet
• transient carriers, acute carriers
• interrupt transmission
• antibiotics
• Streptococcus agalactiae
• same as above
• Streptococcus pneumonia
• person-to-person, direct, respiratory droplet
• healthy transient carriers
• pneumococcal vaccine
• antibiotics
• Streptococcus viridians
• opportunism by normal microflora
• antibiotic prophylaxis
• Enteococcus faecalis/faecium

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Gram-negative cocci

• Neisseria
• aerobic, gram-negative cocci typically in pairs
• catalase positive
• oxidase positive
• utilize carbohydrates oxidatively, not
  fermentatively
• fastidious
• colonize mucosal surfaces
• two primary pathogens
• Neisseria gonorrhoeae
• Neisseria meningidits

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Neisseria gonorrhoeae

• Basic of Virulence
• Capsule antiphagocytic pathogenic strains are
  usually encapsulated
• Pilin protein component of pili, mediates
  attachment adhesin
• is genetically controlled with phase shifts in
  expression and composition
• Por protein promotes intracellular survival
• prevents fusion of lysosomes with the phagosome
• Opa protein mediates attachment and entrances
  into cells
• Rmp protein protects surface antigens from
  antibody
• Tbp 12 mediates the acquisition of iron
• with Lbp bind transferrin and lactoferrin and
  extract the iron
• LOS lipopolysaccharide/endotoxin
• stimulates inflammation and release of TNF(alpha)
  symptoms
• antibody against LOS activates complement
  releasing C5a
• IgA protease destroys or cleaves IgA
• destroys IgA antibodies against pilin, Opa, and
  LOS
• beta lactamase penicillinase hydrolyzes the beta
  lactam ring

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Neisseria gonorrhoeae

• Diseases caused by the gonococcus
• urethritis inflammation of the urethra with
  purulent discharge(exudate)
• primary site to infection in males
• cervicitis inflammation of the uterine
  endocervical epithelium
• primary site of infection in female
• vaginal discharge(exudate), dysuria, and
  abdominal pain
• salpingitis(PID) inflammation of the ovarian
  tubules
• proctitis inflammation of the rectum
• common in homosexual and bisexual males
• pharyngitis inflammation of the pharynx
• conjunctivitis inflammation of the conjunctiva
• ophthalmia neonatorium conjunctivitis in
  newborns
• bacteremia bacteria in the blood progressing to
  septicema
• arthritis(septic) dissemination of organism to
  the joints

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Neisseria gonorrhoeae

• Diagnosis of Gonorrhea
• gram stain of urethral/cervical exudate
• most sensitive in symptomatic males
• gram-negative intracellular diplococci within PMN
  leucocytes
• culture grow the organism in the laboratory
• most often performed with urogenital and
  pharyngeal specimen
• selective medium required Thayer-Martin medium
• blood and joint culture can also be performed
• presumptive identification
• gram-negative diplococci which are oxidase
  positive and obtained from growth on
  Thayer-Martin or chocolate agar media Neisseria
• genetic probes
• direct detection of gonococcal DNA in clinical
  specimens
• sensitive, specific, and rapid
• rapidly replacing diagnosis by culture
• serology
• detection of gonococcal antigens
• detection of anti-gonococcal antibody

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Gonorrhea

• Epidemiology
• Human reservoir Neisseria only grow in humans
• many infected persons are asymptomatic carrier
• asymptomatic carriers are much more common among
  females
• much males are initially symptomatic
• Human source Mode of Transmission -
  person-to-person
• horizontal, direct, sexual to adults
• vertical, direct, perinatal to neonates
• Incidence gt 400,00 new cases/yrs
• underreported especially among adolescents
• Prevention
• difficulty of control a disease tied closely to
  sexual promiscuity
• immunity is poor so many reinfections
• chemoprophylaxis is effective only for neonatal
  conjunctivitis
• Treatment
• gonorrhea is a treatable disease using
  antibiotics
• many antibiotic resistant strains have emerged

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Neisseria meningiditis

• Diseases caused by the meningococcus
• bacterial meningitis
• abrupt onset of headache, stiffness in neck and
  back, and fever
• symptoms less specific in children
• septicemia(meningococcemia)
• with or without meningitis
• thrombosis of small blood vessels in many organs
• petechial lesions(hemmorrhagic) on trunk and
  lower extremities
• disseminated intravascular coagulation and shock
• bilateral destruction of the adrenal glands
  Waterhouse-Friderichsen Syndro
• pneumonia
• less common manifestation
• usually secondary to another respiratory
  infection including pharyngitis
• cough, chest pain, rales, fever, chills

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Neisseria meningiditis

• Basis for Virulence
• Capsule
• 13 serogroups with A, B, C, X, Y, and W135 most
  common
• imparts antiphagocytic properties to the
  meningococci
• LOS/endotoxin
• responsible for diffuse vascular damage
• severe endotoxin reactions
• pili mediates attachment to receptors on cells of
  nasopharynx
• hemolysin facilitates movement into the blood
• Diagnosis
• gram stain
• CSF with gram-negative diplococci within
  polymorphonuclear leukocytes
• culture
• blood or cerebrospinal fluid specimens
• it is relatively easy to detect and grow
  meningococci for CSF of untreated patients
  because of the large number of bacteria per
  milliliter
• serology
• detect antibody against specific capsular
  polysaccharides

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Meningococcal Diseases

• Epidemiology
• Human Reservoir humans are the only natural
  carriers of the bacteium
• Human Source person-to-person
• direct, respiratory droplet
• Incidence
• endemic meningococcal disease occurs worldwide
• periodic epidemics occur among susceptible groups
• In U.S. , this is the second most common cause of
  community-acquired meningitis in adults
• serogroups A, B, C, cause most disease, with
  group B most common in U.S.
• oral and nasopharyngeal carriers are significant
  components of reservoir

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Meningococcal Diseases

• Prevention
• eradicate the pool of healthy carriers
• this is impossible to accomplish
• those identified can be treated prophylactically
  with antibiotics
• also exposed susceptible(s) can be treated
  chemoprophylactically
• polysaccharide vaccines exist for some serogroups
• Treatment
• antibiotic treatment if started earlier can alter
  the course of the disease
• mortality approaches 100 in untreated cases
• Penicillin(s) are currently agents of choice
• antibiotic resistant strains have begun to occur

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Gram-positive, sporeforming, bacilli

• Genus Bacillus
• Characteristics
• gram-positive, endospore forming, bacilli
• aerobe to facultative anaerobes
• most are motile
• catalase-positive
• common soil saprophytes
• Pathogens Bacillus anthracis, Bacillus cereus
• Genus Clostridium
• Characteristics
• gram-positive, endospore forming bacilli
• obligate(strict) anaerobes
• complex metabolism
• ubiquitous soil, water, sewage, animal intestinal
  microflora
• Pathogens Clostridum tetani, Cl. botulinum, Cl.
  perfingens
• Cl. difficile

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Bacillus anthracis

• Diseases caused by Bacillus anthracis
• Anthrax Zoonosis in herbivore animals
• cutaneous anthrax
• malignant pustule portal of entry skin
• source contaminated soil or infected animal
  products
• painless papule at site, then ulcerates, and
  necrosis
• localized edema
• 20 mortality untreated
• inhalation anthrax
• woolsorters disease portal of entry lower
  respiratory(lungs)
• source is infected animal hides
• mild URT symptoms followed by rapid pulmonary
  invasion and respiratory failure
• high mortality because of late diagnosis
• gastrointestinal anthrax
• rare manifestation from ingestions of endospores

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Bacillus anthracis

• Basis of Virulence
• Capsule
• composed of a peptide consisting only of glutamic
  acid
• antiphagocytic antibodies against it are not
  protective
• Exotoxin
• inhibits phagocytosis and blocks leukocyte
  oxidative activity
• three components
• protective antigen
• edema factor
• lethal factor
• protective antigen plus edema factor edema
• protective antigen plus lethal factor death

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Bacillus cereus

• Diseases caused by Bacillus cereus
• Food Poisoning intoxication type gastroenteritis
• emetic form vomiting, nausea, abdominal cramps
• heat stable
• incubation lt 6 hrs
• source rice and pasta containing performed
  enterotoxin
• diarrheal form diarrhea, nausea, abdominal cramps
• heat labile
• activates adenylate cyclase in intestinal
  epithelial cells
• incubation gt 6 hrs
• source various foods, i.e. meat, vegetables
• may be preformed or synthesized in the intestines
• Ocular Infections rapid destruction of the eye
  due to 3 toxins
• necrotic toxin enterotoxin
• cereolysin potent hemolysin
• phospholipase C lecithinase

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Bacillus anthracis

• Epidemiology
• reservoir herbivore animals zoonosis
• also soil is a reservoir for animal infection
• endospores survive in soil for years
• source animal skin, hair, wool
• contain endospores
• portal of entry skin malignant pustule, lungs
  woolsorters diseas
• Prevention
• proper disposal of infected animals
• vaccination of animals/humans
• Treatment
• antibiotic treatment
• most successful with malignant pustule

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Bacillus cereus

• Epidemiology
• reservoir the soil
• source foods contaminated with endospores from
  dust/soil
• also fomites which penetrate the eye or skin
• Prevention
• proper refrigeration of suspect foods
• keep suspect food hot
• Treatment
• eye infections treated with antibiotics

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Clostridium tetani

• Diseases caused by Clostridium tetani
• tetanus maximum sustained contraction of skeletal
  muscles
• generalized most common form involving masseter
  muscles, back contractions, cardiac arrhymias,
  profuse sweating
• cephalic primary site of infection is the head
• localized symptoms confined to musculature at
  site of infection
• neonatal generalized tetanus resulting from
  umbilical stump infection
• Basis of Virulence
• tetanospasmin
• neurotoxin blocks release of inhibitory
  neurotransmitters causing unregulated excitatory
  synaptic activity in motor nerves
• plasmid-encoded, heat labile
• A-B toxin, released upon cell lysis, binds
  irreversibly
• tetanolysin
• oxygen-labile hemolysin

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Clostridium tetani

• Prevention of Tetanus
• Proper treatment of deep puncture wounds
• clean and disinfect the wound
• stop the bleeding
• keep aerobic
• Immunization
• basis in artificial active immunity
• vaccine contains tetanus toxoid inactive/antigenic
  tetanospasmin
• given in the polyvalent vaccine, DPT or DT
• Treatment of Tetanus
• Antitoxin artificial passive immunity
• Antibioitic

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Clostridium botulinum

• Diseases caused by Clostridium botulinum
• botulism bilateral descending weakness of
  peripheral muscles terminating with respiratory
  paralysis
• other symptoms blurred vision, dry mouth,
  constipation, abdominal pain
• food borne intoxication
• infant botulism same symptoms as above with
  failure to cry and to thrive a basis for sudden
  infant death syndrome
• due to intestinal colonization of
  gastrointestinal tract
• wound botulism same symptoms
• due to infection in soil contaminated wounds
• Basis of Virulence
• botulinum toxin(s)
• binds specifically to cholinergic nerves
• blocks the release of acetylcholine at peripheral
  synapses
• A-B toxin with seven antigenic variants- A, B, E,
  F, are most common
• binds irreversibly

66
Clostridium botulinum

• Epidemiology of botulism
• common source food borne poisoning of the
  intoxication type
• commonly associated with water-based canned foods
• home canned foods account for 85 of botulism
  cases
• commercially canned foods for 15 of botulism
  cases
• some cases involve other types of foods
• Prevention of botulism
• sterilization of water-based canned foods
• pickling
• freezing
• avoid giving honey to infants
• Treatment of botulism
• botulism antitoxins, A, B, E, artificial passive
  immunity
• gastric lavage

67
Clostridium perfringens

• Diseases/Infections involving Clostridium
  perfringens
• gas gangrene(myconecrosis) extensive muscle
  necrosis
• soft tissue infections(cellulitis) organism grows
  in the fascial planes
• food poisoning abdominal cramps and diarrhea
• necrotizing enteritis acute necrosis of the
  jejunum
• septicemia generally not significant
• Basis of Virulence
• alpha toxin lecithinase, hemolytic, gtvascular
  permeability
• a lecithinase, zinc metallophospholipase,
  hydrolyzes the phosphatylcholine and
  sphingomyelin in eucarytoic cell membrane cell
  death
• Clostridium group A toxin responsible for
  myonecrosis
• beta toxin necrosis, causes release of
  catecholamine
• iota toxin necrosis and increased vascular
  permeability
• enterotoxin cytotoxic, alters membrane
  permeability
• misc enzymes(toxins) see table 37-2

68
Clostridium perfringens

• Epidemiology
• Reservoir soil, water, sewage, human/animal
  intestines
• Source contaminated sharp objects, meat products
• Portal of Entry integument via wounds,
  gastrointestinal tract via ingestion of
  endospores
• Example meat, fish, or poultry containing
  endospores is cooked spores are not killed food
  is incubated at warm(room) temperature and spores
  germinate if food is not adequately reheated,
  vegetative cells are ingested and sporulate in
  the intestine This sporulation process releases
  the enterotoxin
• Prevention
• rapid and adequate treatment of wounds
• debridement
• keep aerobic
• refrigerate high risk foods to prevent spores
  from germinating

69
Clostridium difficile

• Diseases caused by Clostridium difficile
• antibiotic associated colitis
• antibiotic associated pseudomembranous colitis
• Basis of Virulence
• enterotoxin - stimulates neutrophil chemotaxis,
  cytokine release with accompanying inflammation,
  hypersecretion of fluid, and hemorrhagic necrosis
• cytotoxin - depolymerizes actin, thus destroying
  the cellular cytoskeleton
• adhesin factor mediates binding to colonic cells,
  esp ileum
• hyaluronidase hydrolyzes intestinal hyaluronic
  acid
• spore formation past for long term survival

70
Clostridium difficile

• Epidemiology of Antibiotic-associated
  enterocolitis
• This is an example of opportunism
• Clostridium difficile is part of the normal
  microflora in many healthy and hospitalized
  people
• In most people it is sufficiently antagonized and
  its endospores are latent
• Many antibiotics, especially those taken orally,
  kill the antagonistic microflora, thus allowing
  this organism to germinate and grow
• Prevention
• This condition is difficult to prevent
• The organism is common in hospitals
• Antibiotics are necessary to control other
  infections

71
Mycobacteria

• Characteristics
• non-motile, non-sporeforming, aerobic bacilli
• sometimes forms branched filaments
• cell wall contains many lipids
• mycolic acids, 60-90 carbon fatty acids
• makes the bacterial surface hydrophobic and
  resistance to disinfectants/antibiotics and
  drying
• basis of the cells acid-fast staining properties
• basis of cells antigenicity
• acid-fast
• Ziehl-Nielson Staining method
• fastidious, slow growing bacteria
• generation time 12-24 hrs
• only a few are pathogenic for humans
• Mycobacterium tuberculosis, Myco. leprae, Myco.
  avium, Myco. kansasii,

72
Mycobacterium tuberculosis

• Disease caused by Mycobacterium tuberculosis
• tuberculosis localized granulatous infection of
  the lungs which disseminates to many other
  sites
• inhaled bacteria replicate freely in un-
  activated alveolar macrophages
• bacilli, cell debri, chemotactic factors attract
  other macrophage and lymphocytes into the
  area(focus)
• macrophages fuse at focus forming multinucleated
  giant cells, Langhans Cells
• T-helper(CD-4) and cytotoxic T-cells(CD-8) cells
  attracted to focus and become activated
• T-cells release gamma-interferon and cytokines
  which activate the macrophages. This permitted
  macrophage killing of bacteria and infected
  phagocytic cells
• Tissue necrosis, tubercles, result from activated
  macrophage activity
• Basis of Virulence
• mycolic acids
• cord factor glycolipids,waxes, mycosides
  promotes the intracellular survival of the
  replicating bacteria
• host immune response cellular(T-cell) based
  immunity

73
Mycobacterium tuberculosis

• Epidemiology
• Reservoir humans
• Source infected humans
• Portal of Entry lower respiratory tract/lungs
• Incidence
• 8 million new cases annually worldwide/2500 in
  U.S.
• 3 million deaths annually worldwide
• Mode of Transmission
• person-to-person, direct, respiratory droplets
• person-to-person, indirect, environmental
  aerosol(dried sputum)
• Prevention/Control
• early diagnosis and treatment
• drug resistance is beginning to slow
  effectiveness of treatment
• skin testing/chest X-rays
• Mantoux test PPD
• BCG vaccine

74
Mycobacterium leprae

• Disease caused by Mycobacterium leprae
• leprosy( Hansens disease) a chronic disease
• tuberculoid leprosy a infection of the
  peripheral nerves in the cooler regions of
  the body, ie, extremities, face
• some erythrematous cutaneous lesions
• macrophages and cellular immune factors limit
  infection
• lepromatous leprosy severe nerve damage and
  extensive cutaneous involvement with spread to
  other areas
• cellular immunity declines allowing the infection
  to spread
• this is the terminal phase of leprosy
• Basis of Virulence
• same as with Mycobacterium tuberculosis
• survives and multiples intracellularly in
  macrophages
• Epidemiology/Prevention
• human reservoir with p-p, direct, contact,
  transmission
• interrupt transmission cycle and treat infected
  patients

75
Gram-positive, Non-sporeforming Bacilli

• Diseases caused by gram-positive, nonsporeforming
  bacilli
• Diphtheria
• Corynebacterium diphtheriae
• Not motile
• Lack of motility differentiates coryneform
  bacteria from Listeria
• Listerosis highest mortality of any food-borne
  illness, second only to botulism
• Listeria monocytogenes grows in refrigerated
  foodscold enrichment
• Motile a 22-28 C end-over-end pattern
• Not motile at 37 C

76
Corynebacterium diphtheriae

• Diphtheria is an upper respiratory infection in
  which localized damage creates a
  pseudomembrane from the tonsils to the larynx.
• sudden onset of fever, malaise, exudative
  pharyngitis
• systemic toxemia damages heart and nerves
• Basis of Virulence
• exotoxin
• tox gene codes an A-B toxin consisting of two
  peptides linked by disulfide bonds
• three functional regions 1. receptor binding
  region 2. translocation region 3. catalytic
  region
• host cells receptor heparin binding epidermal
  growth factor present on the surface of most
  eucaryotic cells especially heart and nerve.
• terminates host cell protein synthesis by
  inactivating elongation factor-2
• Epidemiology/Control
• human reservoir
• Transmission p-p, direct, respiratory droplet
• toxoid based vaccine the D in DPT

77
Listeria monocytogenes

• Listerosis
• early neonatal due toin utero infection
  causing disseminated abscesses and granulomas in
  multiple organs
• late neonatal meningitis or meningoencephalitis
  with septicemia three weeks post-partum
• Adults most immunocompromised
• Meningoencephalitis following bacteremia
• Adults immunocompetent
• fever-chills with mild gastroenteritis
• Basis of Virulence
• Promotes phagocytosis into epithelial cells lt pH
  activatates listerolysin O which lyses phagosome
  and releases bacteria into the cytoplasm
  proliferates bacteria affiliate with the cell
  membrane and move from one cell to another by
  filopods
• Epidemiology/Control
• Reservoir common in nature, mammals, fish,
  birds insects, soil, water, vegetation
• Common Source food-borne illness often assoc.
  with dairy products, hot dogs, cold cuts, raw
  vegetables
• Control proper cooking, processing, and storage
  of foods

78
Gram-negative Bacilli

• Enterobacteriaceae
• largest family of pathogenic/opportunistic
  gram-negative bacteria which affect the health of
  humans
• Vibrionaceae
• second largest family of gram-negative pathogens
  affecting humans
• Campylobacteriaceae
• Pseudomonaceae
• Pasteurellaceae
• Legionellaceae
• Misc gram-negative bacilli of uncertain taxonomy

79
Enterobacteriaceae

• Characteristics
• gram-negative bacilli
• Non motile or motile with peritrichous flagella
• facultative anaerobes
• ferment glucose, reduce nitrates,
• catalase positive, oxidase negative
• lactose fermenters not all, only the coliforms
• gastrointestinal microflora of most animals
  including humans
• ubiquitous in fecally contaminated soil, water,
  vegetation
• many pathogens and opportunists
• LPS complex is the major cell wall antigen/heat
  stable lipopolysaccharide
• 1. somatic O polysaccharide 2. core
  polysaccharide 3. lipid A
• serologically classified by antigens
• somatic O polysaccharide antigens part of the
  LPS(endotoxin) complex
• capsular K antigens
• flagellar H antigens

80
Enterobacteriaceae

• Genera of common opportunists/Example
• Escherichia Escherichia coli
• Klebsiella Klebsiella pneumoniae
• Citrobacter Citrobacter freundii
• Enterobacter Enterobacter aerogenes
• Proteus Proteus mirabilis
• Serratia Serratia marcescns
• Genera of common pathogens
• Escherichia Enteropathogenic E.coli
• Salmonella Salmonella typhii
• Shigella Shigella dysenteriae
• Yersinia Yersinia enterocolitica

81
Enterobacteriaceae

• Basis of Virulence
• Endotoxin based in lipid A component of LPS
• activation of complement, release of cytokines,
  leukocytosis, thrombocytopenia, intravascular
  coagulation, fever, decreased peripheral
  circulation, shock, death
• Capsule not present in all strains
• hydrophilic antigens protect bacteria from
  phagocytosis
• interferes with the binding of antibodies to the
  bacterial surface
• Antigenic phase variation capsular K and
  flagellar H antigens
• genetically controlled expression or lack of
  expression
• Sequestration of growth factors
• siderophores, enterobactin and aerobactin,
  extract iron from host cells
• Resistance to serum killing
• factors prevent complement components from
  binding to bacteria
• antibody in serum is prevented from binding by
  capsule
• Antimicrobial(antibiotic) resistance
• plasmid based resistance to chemotherapy

82
Escherichia coli

• Opportunistic diseases involving E. coli
• urinary tract infection urethritis, cystitis,
  pyelonephritis
• neonatal meningitis inflammation of the meninges
• septicemia infection of the blood
• Enteropathogenic diseases involving E. coli
• gastroenteritis(table 29-1)
• enterotoxigenic E. coli
• enteropathogenic E. coli
• enteroinvasive E. coli
• enterohemorrhagic E. coli
• enteroaggregative E. colis
• Basis of Virulence(table 29-4)
• Adhesins
• Exotoxins

83
Clinical diseases involving Escherichia coli

• Urinary Tract Infections
• urethritisurethra cystitisbladder
  pyelonephritiskidney
• most strains cannot cause UTI, but most virulence
  strains possess adhesins
• P pili, AFA-I, AFA- III, Dr bind bacteria to
  epithelia cells lining areas and flow of urine
  does not remove them
• 80 of community-acquired UTIs, most
  hospital-acquired UTIs
• Neonatal Meningitis
• most(75) strains possess K1 capsular
  antigen(antiphagocytic)
• along with group B streptococci is most common
  cause of this disease
• Septicemia
• a complication of infection in the urinary tract
  or gastrointestinal tract
• most common gram-negative bacteria isolated from
  septic patients
• Gastroenteritis
• infection of the intestinal mucosa
• cramps, nausea, vomiting, and water diarrhea

84
Enteropathogenic Escherichia coli

• Enterotoxigenic E.coli(ETEC)
• a secret