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Bacterial Diseases

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Gonorrhea. Females. vaginitis, urethritis, salpingitis (PID) mixed anaerobic abdominal infection ... Gonorrhea in Newborns. Infected as they pass through birth ... – PowerPoint PPT presentation

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Title: Bacterial Diseases


1
Bacterial Diseases
  • Lecture 10

2
Cocci of Medical Importance
3
General Characteristics of the Staphylococci
  • Spherical cells arranged in irregular clusters
  • Gram positive
  • Common inhabitant of the skin mucous membranes
  • Lack spores and flagella
  • May have capsules
  • 31 species

4
Staphylococcus aureus
  • grows in large, round, opaque colonies
  • optimum temperature 37oC
  • facultative anaerobe
  • withstands high salt, extremes in pH, high
    temperatures
  • produces many virulence factors

5
Enzymes of S. aureus
  • Coagulase
  • coagulates plasma and blood
  • produced by 97 of human isolates
  • Hyaluronidase
  • promotes invasion
  • Staphylokinase
  • digests blood clots
  • Dnase
  • digests DNA
  • Lipases
  • helps bacteria colonize oily skin
  • Penicillinase
  • inactivates penicillin

6
Toxins of S. aureus
  • hemolysins
  • lyse RBCs
  • Leukocidin
  • damages cell membranes
  • Enterotoxins
  • act in the gastrointestinal tract
  • exfoliative toxin
  • separates epidermal layers
  • toxic shock syndrome toxin (TSST)

7
Epidemiology and Pathogenesis
  • Present in most environments frequented by humans
  • Readily isolated from fomites
  • Carriage rate for healthy adults is 20-60
  • mostly in anterior nares, skin, nasopharynx,
    intestine
  • Predisposition to infection include
  • poor hygiene and nutrition, tissue injury,
    preexisting primary infection, diabetes,
    immunodeficiency
  • Increase in community acquired methicillin
    resistance
  • MRSA

8
Staphylococcal Disease
  • Range from localized to systemic
  • Localized cutaneous infections invade skin
    through wounds, follicles, or glands
  • folliculitis
  • superficial inflammation of hair follicle
  • usually resolved with no complications but can
    progress
  • furuncle
  • Boil
  • inflammation of hair follicle or sebaceous gland
    progresses into abscess or pustule
  • carbuncle
  • larger and deeper lesion created by aggregation
    and interconnection of a cluster of furuncles
  • impetigo
  • bubble-like swellings that can break and peel
    away
  • most common in newborns

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10
Staphylococcal Disease
  • Systemic infections
  • osteomyelitis
  • infection is established in the metaphysis
  • abscess forms
  • bacteremia
  • primary origin is bacteria from another infected
    site or medical devices
  • endocarditis possible

11
Staphylococcal Disease
  • Toxigenic disease
  • food intoxication
  • ingestion of heat stable enterotoxins
  • gastrointestinal distress
  • staphylococcal scalded skin syndrome
  • toxin induces bright red flush, blisters, then
    desquamation of the epidermis
  • toxic shock syndrome
  • toxemia leading to shock and organ failure

12
Other Staphylococci
  • S. epidermidis
  • lives on skin mucous membranes
  • endocarditis, bacteremia, UTI
  • S. hominis
  • lives around apocrine sweat glands
  • S. capitis
  • live on scalp, face, external ear
  • S. saprophyticus
  • infrequently lives on skin, intestine, vagina UTI

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15
Streptococci
  • Gram-positive spherical/ovoid
  • cocci arranged in long chains
  • Non-spore-forming, nonmotile
  • Can form capsules slime layers
  • Facultative anaerobes
  • Do not form catalase, but have a peroxidase
    system
  • Small, nonpigmented colonies
  • Sensitive to drying, heat disinfectants
  • 25 species

16
Streptococci
  • Lancefield classification system based on cell
    wall Ag
  • 17 groups (A,B,C,.)
  • Another classification system is based on
    hemolysis reactions
  • b-hemolysis
  • A,B,C,G some D strains
  • a hemolysis
  • S. pneumoniae others collectively called
    viridans
  • ?-hemolysis
  • Enterococcus faecalis
  • does not induce hemolysis

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19
Human Streptococcal Pathogens
  • S. pyogenes
  • S. agalactiae
  • viridans streptococci
  • S. pneumoniae
  • Enterococcus faecalis

20
b-hemolytic S. pyogenes
  • Most serious streptococcal pathogen
  • Inhabits throat, nasopharynx, occasionally skin
  • Produces C-carbohydrates, M-protein (fimbrae),
    streptokinase, hyaluronidase, DNase, hemolysins
    (SLO, SLS), pyogenic toxin

21
S. pyogenes
  • Humans only reservoir
  • Transmission
  • contact, droplets, food, fomites
  • Skin infections
  • pyoderma, impetigo, erysipelas
  • Systemic infections
  • strep throat, pharyngitis, scarlet fever
  • Sequelae
  • rheumatic fever, glomerulonephritis

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Group B S. agalactiae
  • Regularly resides in human vagina, pharynx
    large intestine
  • can be transferred to infant during delivery
    cause severe infection
  • Most prevalent cause of neonatal pneumonia,
    sepsis, meningitis
  • Pregnant women should be screened treated
  • wound and skin infections endocarditis in
    debilitated people

24
Scope of Clinical Disease
  • Skin infections
  • Impetigo (pyoderma)
  • superficial lesions that break and form highly
    contagious crust
  • often occurs in epidemics in school children
  • associated with insect bites, poor hygiene, and
    crowded living conditions
  • Erysipelas
  • pathogen enters through a break in the skin
  • eventually spreads to the dermis and subcutaneous
    tissues
  • can remain superficial or become systemic
  • Throat infections
  • Streptococcal pharyngitis
  • strep throat

25
Long-Term Complications
  • Rheumatic fever
  • follows overt or subclinical pharyngitis in
    children
  • carditis with extensive valve damage possible,
    arthritis, chorea, fever
  • Acute glomerulonephritis
  • nephritis, increased blood pressure, occasionally
    heart failure
  • can become chronic leading to kidney failure

26
Enterococcus faecalis E. faecium
  • Normal colonists of human large intestine
  • Cause opportunistic urinary, wound, and skin
    infections, particularly in debilitated persons

27
Viridans Group
  • a-hemolytic streptococci
  • Large complex group
  • Most numerous widespread residents of the oral
    cavity
  • also found in nasopharynx, genital tract, skin
  • Not very invasive
  • dental or surgical procedures facilitate entrance

28
Viridans Group
  • Bacteremia, meningitis, abdominal infection,
    tooth abscesses
  • S. mutans produces slime layers that adhere to
    teeth
  • basis for plaque
  • involved in dental caries
  • Most serious infection
  • subacute endocarditis
  • blood-borne bacteria settle grow on heart
    lining or valves
  • preexisting heart disease at high risk
  • receive prophylactic antibiotics before surgery
    or dental procedures

29
S. pneumoniae
  • Causes 60-70 of all bacterial pneumonias
  • Small, lancet-shaped cells arranged in pairs and
    short chains
  • Culture requires blood or chocolate agar
  • Growth improved by 5-10 CO2
  • Lack catalase peroxidases
  • cultures die in O2

30
S. pneumoniae
  • All pathogenic strains form large capsules
  • major virulence factor
  • Causes pneumonia otitis media
  • Vaccine available for high risk people

31
S. Pneumoniae Epidemiology
  • 5-50 of all people carry it as normal flora in
    pharynx
  • Does not survive long outside of its habitat
  • Pneumonia occurs when cells are aspirated into
    the lungs of susceptible individuals
  • Pneumococci multiply
  • induce inflammatory response
  • Traditionally treated with penicillin G or V
  • Increased drug resistance

32
Cultivation and Diagnosis
  • Gram stain of specimen
  • presumptive identification
  • a hemolytic
  • Quellung test or capsular swelling reaction

33
Family Neisseriaceae
  • Gram-negative cocci
  • Residents of mucous membranes of warm-blooded
    animals
  • Genera include Neisseria, Moraxella,
    Acinetobacter
  • 2 primary human pathogens
  • Neisseria gonorrhoeae
  • Neisseria meningitidis

34
Neisseria
  • Gram-negative, bean-shaped, diplococci
  • none develop flagella or spores
  • capsules on pathogens
  • pili
  • Strict parasites
  • do not survive long outside of the host
  • Aerobic or microaerophilic
  • Oxidative metabolism
  • produce catalase
  • Pathogenic species require enriched complex media
    and CO2

35
Neisseria gonorrhoeae
  • Causes gonorrhea
  • Virulence factors
  • pili, other surface molecules, IgA protease
  • Strictly a human infection
  • In top 5 STDs
  • Infectious dose 100-1,000
  • Does not survive more than 1-2 hours on fomites
  • Infection is asymptomatic in 10 of males and
    50 of females

36
Gonorrhea
  • Males
  • urethritis, yellowish discharge, scarring
    infertility
  • Extragenital infections
  • anal, pharygeal, conjunctivitis, septicemia,
    arthritis

37
Gonorrhea
  • Females
  • vaginitis, urethritis, salpingitis (PID) mixed
    anaerobic abdominal infection
  • common cause of sterility ectopic tubal
    pregnancies

38
Gonorrhea in Newborns
  • Infected as they pass through birth canal
  • Eye inflammation, blindness
  • Prevented by prophylaxis after birth

39
Diagnosis and Control
  • Gram stain
  • Gram-negative intracellular (neutrophils)
    diplococci from urethral, vaginal, cervical, or
    eye exudate
  • 20-30 of new cases are penicillinase-producing
    PPNG or tetracycline resistant TRNG
  • Recurrent infections can occur
  • Reportable infectious disease

40
Neisseria meningitidis
  • Virulence factors
  • capsule, pili, IgA protease
  • 12 strains
  • serotypes A, B, C, cause most cases
  • Disease begins when bacteria enter bloodstream,
    pass into cranial circulation, multiply in
    meninges
  • very rapid onset
  • endotoxin causes hemorrhage and shock
  • can be fatal
  • Treated with penicillin, chloramphenicol
  • Vaccines exist for group A and C

41
Clinical Diagnosis
  • Gram stain, CSF, blood, or nasopharyngeal sample
  • Culture for differentiation
  • Rapid tests for capsular antigen

42
Gram-negative Bacilli of Medical Importance
43
Gram-negative Bacilli
  • Large, diverse group of non-spore-forming
    bacteria
  • Wide range of habitats
  • large intestines (enteric), zoonotic,
    respiratory, soil, water
  • Most are not medically important
  • true pathogens
  • opportunists
  • All have a lipopolysaccharide outer membrane of
    cell wall
  • endotoxin

44
Aerobic Gram-Negative Bacilli
  • 1. Pseudomonas
  • 2. Brucella
  • 3. Francisella
  • 4. Bordetella
  • 5. Legionella
  • 6. Alcaligenes

45
1. Pseudomonas
  • small gram-negative rods
  • single polar flagellum
  • produce oxidase catalase
  • highly versatile metabolism

46
Pseudomonas aeruginosa
  • intestinal resident in 10 normal people
  • resistant to soaps, dyes, quaternary ammonium
    disinfectants, drugs, drying
  • Use aerobic respiration
  • do not ferment carbohydrates
  • Produce oxidase and catalase
  • Many produce water soluble pigments
  • Opportunistic

47
Pseudomonas aeruginosa
  • common cause of nosocomial infections in hosts
    with burns, neoplastic disease, cystic fibrosis
  • complications include pneumonia, UTI, abscesses,
    otitis, corneal disease
  • grapelike odor
  • greenish-blue pigment (pyocyanin)
  • multidrug resistant
  • cephalosporins, aminoglycosides, carbenicillin,
    polymixin, quinolones

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49
2. Brucella
  • Brucellosis, malta fever, undulant fever, Bang
    disease
  • zoonosis transmitted to humans from infected
    animals
  • tiny gram-negative coccobacilli
  • 2 species
  • Brucella abortus (cattle)
  • Brucella suis (pigs)
  • fluctuating pattern of fever
  • weeks to a year
  • combination of tetracycline
  • rifampin or streptomycin
  • animal vaccine available
  • potential bioweapon

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3. Francisella tularensis
  • causes tularemia
  • zoonotic disease of mammals (particularly
    rabbits)
  • endemic to the northern hemisphere
  • transmitted by contact with infected animals,
    water dust or bites by vectors
  • headache, backache, fever, chills, malaise
    weakness
  • 10 death rate in systemic pulmonic forms
  • intracellular persistence can lead to relapse
  • gentamicin or tetracycline
  • potential bioterrorism agent

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53
4. Bordetella pertussis
  • minute, encapsulated coccobacillus
  • causes pertussis or whooping cough
  • communicable childhood affliction
  • acute respiratory syndrome
  • often severe, life-threatening complications in
    babies
  • reservoir
  • apparently healthy carriers
  • transmission by direct contact or inhalation of
    aerosols

54
Bordetella pertussis
  • virulence factors
  • receptors that recognize bind to ciliated
    respiratory epithelial cells
  • toxins that destroy dislodge ciliated cells
  • DTaP vaccine
  • acellular vaccine contains toxoid other Ags

55
5. Legionella pneumophila
  • Legionellosis, Legionaires disease
  • Motile rods
  • widely distributed in water
  • live in close association with amebas
  • prevalent in males over 50
  • nosocomial disease in elderly patients
  • fever, cough, diarrhea, abdominal pain, pneumonia
  • fatality rate of 3-30
  • azithromycin

56
6. Alcaligenes
  • live primarily in soil water
  • may become normal flora
  • A. faecalis
  • most common clinical species
  • isolated from feces, sputum, urine
  • occasionally associated with opportunistic
    infections
  • pneumonia, septicemia, meningitis

57
Enterobacteriaceae Family
  • Enterics
  • gram-negative bacteria
  • many members inhabit soil, water, decaying
    matter
  • all members are small, non-sporing rods
  • facultative anaerobes
  • grow best in air
  • cause diarrhea through enterotoxins
  • divided into coliforms (lactose fermenters) and
    non-coliforms (non lactose fermenters)

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Enterobacteriaceae Family
  • Coliforms in Normal Flora
  • Rapid lactose-fermenting enteric bacteria that
    are normal flora and opportunistic
  • E. coli
  • Enterobacter
  • Serratia
  • Klebsiella
  • Hafnia
  • Citrobacter
  • Noncoliforms in Normal Flora
  • Lactose-negative bacteria that are opportunistic,
    normal gut flora
  • Proteus
  • Providencia
  • Morganella
  • Edwardsiella

60
Enterobacteriaceae Family
  • True Pathogenic Enterics
  • Salmonella typhi
  • S. cholerae-suis
  • S. enteritidis
  • Shigella dysenteriae
  • S. flexneri
  • S. boydii
  • S. sonnei
  • Yersinia enterocolitica
  • Y. pseudotuberculosis
  • True Pathogenic Nonenterics
  • Yersinia pestis

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Testing of Enterics
  • miniaturized, multichambered tube
  • inoculating rod pulled through length of tube
  • carries an inoculum to all chambers

63
Antigens Virulence Factors
  • H
  • flagellar Ag
  • K
  • capsule /or fimbrial Ag
  • O
  • somatic or cell wall Ag
  • endotoxin
  • exotoxins

64
Coliform Organisms and Diseases Escherichia coli
  • most common aerobic non-fastidious bacterium in
    gut
  • _at_ 150 strains
  • Most not infectious

65
Escherichia coli
  • enterotoxigenic E. coli
  • causes severe diarrhea due to heat-labile toxin
    heat-stable toxin
  • stimulate secretion fluid loss
  • also has fimbrae
  • enteroinvasive E. coli
  • causes inflammatory disease of the large
    intestine
  • enteropathogenic E. coli
  • linked to wasting from infantile diarrhea
  • Enterohemorrhagic E. coli
  • Newest strain
  • Can permanently damage kidney

66
Escherichia coli
  • pathogenic strains frequent agents of infantile
    diarrhea
  • greatest cause of mortality among babies
  • causes 70 of travelers diarrhea
  • causes 50-80 UTI
  • indicator of fecal contamination in water

67
Other Coliforms
  • Klebsiella pneumoniae
  • normal inhabitant of respiratory tract
  • large capsule
  • cause of nosocomial pneumonia, meningitis,
    bacteremia, wound infections UTIs
  • Enterobacter
  • UTIs, surgical wounds

68
Other Coliforms
  • Serratia marcescens
  • produces a red pigment
  • causes pneumonia, burn wound infections,
    septicemia meningitis
  • Citrobacter
  • opportunistic UTIs bacteremia

69
Noncoliform Lactose-negative Enterics
  • Proteus
  • Salmonella
  • Shigella

70
1. Proteus
  • Swarms on surface of moist agar in a concentric
    pattern
  • Causes UTI, wound infections, pneumonia,
    septicemia, infant diarrhea

71
2. Salmonella
  • Motile
  • ferments glucose
  • S. typhi
  • typhoid fever
  • ingested bacilli adhere to small intestine
  • cause invasive diarrhea that leads to septicemia
  • S. cholerae-suis
  • pigs
  • S. enteritidis
  • 1,700 serotypes
  • salmonellosis
  • zoonotic
  • gastroenteritis 2-5 days

72
3. Shigella
  • shigellosis
  • incapacitating dysentery
  • S. dysenteriae, S. sonnei, S. flexneri S.
    boydii
  • produce H2S or urease
  • Nonmotile
  • nonencapsulated

73
Shigella
  • invades villus of large intestine
  • can perforate intestine or invade blood
  • enters Peyers patches instigates inflammatory
    response
  • endotoxin exotoxins
  • treatment
  • fluid replacement ciprofloxacin
    sulfa-trimethoprim

74
True Pathogenic Nonenteric Yersinia pestis
  • tiny, gram-negative rod
  • unusual bipolar staining capsules
  • virulence factors
  • capsular envelope proteins protect against
    phagocytosis foster intracellular growth
  • coagulase

75
Yersinia pestis
  • sylvatic plague
  • humans develop plague through contact with wild
    animals
  • urban plague
  • domestic or semidomestic animals or infected
    humans
  • found in 200 species of mammals
  • rodents harbor the organism but do not develop
    the disease
  • flea vectors
  • bacteria replicates in gut, coagulase causes
    blood clotting that blocks the esophagus
  • flea becomes ravenous

76
Pathology of Plague
  • bubonic
  • bacillus multiplies in flea bite, enters lymph,
    causes necrosis swelling in groin or axilla
  • bubo
  • septicemic
  • progression to massive bacterial growth
  • virulence factors cause intravascular coagulation
    subcutaneous hemorrhage purpura
  • black plague
  • pneumonic
  • infection localized to lungs, highly contagious
  • fatal without treatment

77
Plague
  • Treatment
  • streptomycin, tetracycline or chloramphenicol
  • Killed or attenuated vaccine

78
Medically Important Gram-Positive Bacilli
79
Medically Important Gram-Positive Bacilli
  • Three general groups
  • Endospore-formers
  • Bacillus, Clostridium
  • Non-endospore-formers
  • Listeria, Erysipelothrix
  • Irregular shaped and staining properties
  • Corynebacterium, Proprionibacterium,
    Mycobacterium, Actinomyces, Nocardia

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Gram-positive spore-forming bacilli
82
Bacillus
  • gram-positive
  • endospore-forming
  • motile rods
  • mostly saprobic
  • aerobic catalase positive
  • versatile in degrading complex macromolecules
  • source of antibiotics
  • primary habitat is soil
  • 2 species of medical importance
  • Bacillus anthracis
  • Bacillus cereus

83
Bacillus anthracis
  • facultative
  • large, block shaped rods
  • central spores
  • develop under all conditions except in the living
    body
  • virulence factors
  • capsule exotoxins

84
Bacillus anthracis
  • 3 types of anthrax
  • Cutaneous
  • spores enter through skin, black sore
  • least dangerous
  • Pulmonary
  • inhalation of spores
  • Gastrointestinal
  • ingested spores
  • treated with penicillin or tetracycline
  • vaccine
  • toxoid 6X over 1.5 years
  • annual boosters

85
Bacillus cereus
  • common airborne dustborne
  • grows in foods, spores survive cooking
    reheating
  • ingestion of toxin-containing food
  • causes nausea, vomiting, abdominal cramps
    diarrhea
  • 24 hour duration
  • no treatment
  • spores abundant in the environment

86
Clostridium
  • gram-positive
  • spore-forming rods
  • anaerobic catalase negative
  • 120 species
  • oval or spherical spores produced only under
    anaerobic conditions
  • cause wound tissue infections and food
    intoxications

87
Clostridium perfringens
  • causes gas gangrene in damaged or dead tissues
  • 2nd most common cause of food poisoning,
    worldwide
  • virulence factors
  • toxins
  • alpha toxin
  • collagenase
  • hyaluronidase
  • DNase

88
Pathology
  • Not highly invasive
  • requires damaged and dead tissue
  • anaerobic conditions
  • Conditions stimulate spore germination,
    vegetative growth and release of exotoxins
  • Fermentation of muscle carbohydrates results in
    the formation of gas and further destruction of
    tissue

89
Treatment and Prevention
  • Immediate cleansing of dirty wounds, deep wounds,
    decubitus ulcers, compound fractures, and
    infected incisions
  • Debridement of disease tissue
  • Large doses of cephalosporin or penicillin
  • Hyperbaric oxygen therapy
  • No vaccines available

90
Clostridium difficile-Associated Disease (CDAD)
  • Normal resident of colon, in low numbers
  • Causes antibiotic-associated colitis
  • relatively non-invasive
  • treatment with broad-spectrum antibiotics kills
    the other bacteria
  • allowing C. difficile to overgrow
  • Produces enterotoxins that damage intestines
  • Major cause of diarrhea in hospitals
  • Increasingly more common in community acquired
    diarrhea

91
Treatment and Prevention
  • Mild uncomplicated cases respond to fluid and
    electrolyte replacement and withdrawal of
    antimicrobials
  • Severe infections treated with oral vancomycin or
    metronidazole and replacement cultures
  • Increased precautions to prevent spread

92
Tetanus
  • Clostridium tetani
  • Common resident of soil and GI tracts of animals
  • Most commonly among geriatric patients and IV
    drug abusers
  • neonates in developing countries

93
Pathology
  • Spores usually enter through accidental puncture
    wounds, burns, umbilical stumps, frostbite, and
    crushed body parts.
  • Anaerobic environment is ideal for vegetative
    cells to grow and release toxin
  • Tetanospasmin
  • neurotoxin causes paralysis by binding to motor
    nerve endings
  • muscles contract uncontrollably
  • Death most often due to paralysis of respiratory
    muscles

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Treatment and Prevention
  • Treatment aimed at deterring degree of toxemia
    and infection and maintaining homeostasis
  • Control infection with penicillin or tetracycline
  • and muscle relaxants
  • Vaccine available
  • booster needed every 10 years

96
Clostridium botulinum
  • Causes 3 diseases
  • food poisoning
  • spores are in soil, may contaminate vegetables
  • improper canning does not kill spores they
    germinate in the can producing botulinum toxin
  • toxin causes paralysis by preventing release of
    acetylcholine
  • infant botulism
  • caused by ingested spores that germinate
    release toxin
  • wound botulism
  • spores enter wound cause food poisoning symptoms

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Gram-Positive Regular Non-Spore-Forming Bacilli
  • Medically important
  • Listeria monocytogenes
  • Erysipelothrix rhusiopathiae

99
Listeria monocytogenes
  • non-spore-forming gram-positive
  • ranging from coccobacilli to long filaments
  • 1-4 flagella
  • no capsules
  • resistant to cold, heat, salt, pH extremes bile
  • primary reservoir is soil water
  • can contaminate foods grow during refrigeration

100
Listeria monocytogenes
  • Listerosis
  • immunocompromised patients, fetuses neonates
  • affects brain meninges
  • 20 death rate
  • ampicillin trimethoprimsulfamethoxazole
  • Prevention
  • pasteurization cooking

101
Erysipelothrix rhusiopathiae
  • gram-positive rod
  • widely distributed in animals the environment
  • primary reservoir
  • tonsils of healthy pigs
  • enters through skin abrasion, multiplies to
    produce erysipeloid, dark red lesions
  • penicillin or erythromycin
  • vaccine for pigs

102
Gram-Positive Irregular Non-Spore-Forming Bacilli
  • Medically important genera
  • Corynebacterium
  • Proprionibacterium
  • Mycobacterium
  • Actinomyces
  • Nocardia

103
Corynbacterium diptheriae
  • gram-positive irregular bacilli
  • produce catalase
  • 2 stages of disease
  • Local infection
  • upper respiratory tract inflammation
  • sore throat, nausea, vomiting, swollen lymph
    nodes, pseudomembrane formation can cause
    asphyxiation
  • Diptherotoxin production and toxemia
  • target organs primarily heart and nerves

104
Epidemiology and Pathology
  • Reservoir of healthy carriers
  • potential for diphtheria is always present
  • Most cases occur in non-immunized children living
    in crowded, unsanitary conditions
  • Acquired via respiratory droplets from carriers
    or actively infected individuals

105
Corynbacterium diptheriae
  • Diagnostic methods
  • Pseudomembrane and swelling indicative
  • Stains
  • Conditions, history
  • Serological assay
  • Treatment
  • Antitoxin
  • Penicillin or erythromycin
  • Prevented by toxoid vaccine series and boosters

106
Propionibacterium acnes
  • gram-positive rods
  • aerotolerant or anaerobic
  • nontoxigenic
  • common resident of sebaceous glands
  • causes acne

107
Mycobacteria
  • gram-positive irregular bacilli
  • acid-fast staining
  • strict aerobes
  • produce catalase
  • possess mycolic acids a unique type of
    peptidoglycan
  • do not form capsules, flagella or spores
  • grow slowly
  • 2 medically important
  • Mycobacterium tuberculosis
  • Mycobacterium leprae

108
Mycobacterium tuberculosis
  • produces no exotoxins or enzymes
  • contain complex waxes cord factor
  • prevent destruction by lysosomes of macrophages
  • transmitted by airborne respiratory droplets
  • only 5 infected people develop clinical disease

109
Primary TB
  • infectious dose 10 cells
  • phagocytosed by alveolar macrophages
  • multiply intracellularly
  • after 3-4 weeks immune system attacks, forming
    tubercles
  • granulomas consisting of a central core
    containing bacilli surrounded by WBCs

110
Secondary TB
  • reactivation of bacilli
  • tubercles expand drain into the bronchial tubes
    upper respiratory tract
  • gradually patient experiences more severe
    symptoms
  • violent coughing, greenish or bloody sputum,
    fever, anorexia, weight loss, fatigue
  • untreated 60 mortality rate

111
Extrapulmonary TB
  • during secondary TB, bacilli disseminate to
    regional lymph nodes, kidneys, long bones,
    genital tract, brain, meninges
  • these complications are grave

112
Diagnosis
  • in vivo or tuberculin testing
  • X rays
  • direct identification of acid-fast bacilli in
    specimen
  • cultural isolation and biochemical testing

113
Treatment of TB
  • 6-24 months of at least 2 drugs from a list of 11
  • one pill regimen called Rifater (isoniazid,
    rifampin, pyrazinamide)
  • vaccine based on attenuated bacilli Calmet-Guerin
    strain of M. bovis used in other countries

114
Mycobacterium leprae
  • Hansens bacillus
  • strict parasite
  • slowest growing of all species
  • multiplies within host cells in large packets
    called globi
  • causes leprosy
  • chronic disease that begins in the skin mucous
    membranes progresses into nerves

115
Leprosy (Hansens Disease)
  • spread through direct inoculation from leprotics
  • 2 forms
  • tuberculoid
  • superficial infection without skin disfigurement
  • damages nerves and causes loss of pain perception
  • lepromatous
  • deeply nodular infection
  • causes severe disfigurement of the face
    extremities

116
Diagnosing
  • Combination of symptomology, microscopic
    examination of lesions, and patient history
  • Detection of acid-fast bacilli in skin lesions,
    nasal discharges, and tissue samples

117
Treatment and Prevention
  • Treatment by long-term combined therapy
  • Prevention requires constant surveillance of high
    risk populations
  • WHO sponsoring a trial vaccine

118
Actinomycetes Filamentous Bacteria
  • Genera Actinomyces Nocardia are nonmotile
    filamentous bacteria related to mycobacteria
  • Actinomyces sp
  • responsible for diseases of the oral cavity
    intestines
  • Nocardia brasiliensis
  • causes pulmonary disease similar to TB

119
Miscellaneous Bacterial Disease Agents
120
Spirochetes
  • Gram negative human pathogens
  • Treponema
  • Leptospira
  • Borrella

121
1. Treponema
  • thin, regular, coiled cells
  • live in the oral cavity, intestinal tract,
    perigenital regions of humans animals
  • pathogens are strict parasites

122
Treponema pallidum
  • human is the natural host
  • extremely fastidious sensitive
  • cannot survive long outside of the host
  • causes syphilis
  • infectious dose is 57 organisms

123
Pathogenesis and Host Response
  • Spirochete binds to epithelium, multiplies, and
    penetrates capillaries.
  • Moves into circulation and multiplies
  • Untreated marked by stages
  • Primary
  • Secondary
  • Tertiary
  • Spirochete appears in lesions and blood during
    first 2 stages
  • communicable

124
Stages of Syphilis
  • Primary syphilis
  • appearance of hard chancre at site of inoculation
  • chancre heals spontaneously
  • Secondary syphilis
  • fever, headache, sore throat, red or brown rash
    on skin, palms and soles
  • rash disappears spontaneously

125
Stages of Syphilis
  • Tertiary syphilis
  • about 30 of infections enter in tertiary stage
  • can last for 20 years or longer
  • neural, cardiovascular symptoms, gummas develop
  • Congenital syphilis
  • nasal discharge, skin eruptions, bone
    deformation, nervous system abnormalities

126
Diagnosis and Treatment
  • Stages of syphilis mimic other diseases
  • Consider symptoms, history, microscopic and
    serological testing
  • Treatment
  • penicillin G

127
2. Leptospira
  • tight, regular individual coils with a bend or
    hook at one or both ends
  • L. biflexa
  • harmless, free-living saprobe
  • L. interrogans
  • causes leptospirosis
  • zoonosis
  • bacteria shed in urine
  • infection occurs by contact
  • targets kidneys, liver, brain, eyes
  • sudden high fever, chills, headache, muscle
    aches, conjunctivitis, vomiting

128
3. Borrelia
  • Borrelioses
  • transmitted by arthropod vector
  • B. hermsii
  • relapsing fever
  • B. burgdorferi
  • Lyme disease

129
B. hermsii - Relapsing Fever
  • mammalian reservoirs
  • squirrels, chipmunks, wild rodents
  • tick-borne
  • after 2-15-day incubation, patients have high
    fever, shaking, chills, headache, fatigue
  • Nausea, vomiting, muscle aches, abdominal pain
  • extensive damage to liver, spleen, heart,
    kidneys, cranial nerves
  • parasite changes immune system tries to control
    it
  • recurrent relapses
  • tetracycline

130
B. burgdorferi - Lyme Disease
  • transmitted by ticks
  • complex 2-year cycle involving mice deer
  • nonfatal, slowly progressive syndrome that mimics
    neuromuscular rheumatoid conditions
  • Symptoms
  • 70 get bulls eye rash
  • fever, headache, stiff neck, dizziness
  • if untreated can progress to cardiac
    neurological symptoms, polyarthritis
  • tetracycline, amoxicillin
  • vaccine for dogs, human vaccine discontinued
  • insect repellant containing DEET

131
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132
Curviform Gram-negative Bacteria
  • 1. Vibrio
  • Comma shaped rods with single flagella
  • 2. Camphylobacter
  • Short spirals with one or more flagella
  • 3. Helicobacter
  • Spirochete with spirals and endoflagella

133
1. Vibrio cholera
  • Cholera
  • top 7 causes of morbidity mortality
  • ingested with food or water
  • infectious dose 108

134
Vibrio cholera
  • infects surface of small intestine, noninvasive
  • cholera toxin causes electrolyte water loss
    through secretory diarrhea, resulting dehydration
    leads to muscle, circulatory, neurological
    symptoms
  • Treatment
  • oral rehydration, tetracycline
  • vaccine

135
2. Campylobacter jejuni
  • important cause of bacterial gastroenteritis
  • transmitted by beverages food
  • reach mucosa at the last segment of small
    intestine near colon
  • adhere, burrow through mucus and multiply
  • symptoms of headache, fever, abdominal pain,
    bloody or watery diarrhea

136
3. Helicobacter pylori
  • curved cells discovered in 1979 in stomach
    biopsied specimens
  • causes 90 of stomach duodenal ulcers
  • people with type O blood have a 1.5-2X higher
    rate of ulcers
  • produces large amounts of urease

137
Medically Important Bacteria of Unique Morphology
and Biology
  • 1. Rickettsias
  • 2. Chlamydias
  • 3. Mycoplasmas

138
1. Rickettsia
  • obligate intracellular parasites
  • gram-negative cell wall
  • among the smallest bacteria
  • nonmotile pleomorphic rods or coccobacilli
  • ticks, fleas louse are involved in their life
    cycle
  • bacteria enter endothelial cells cause necrosis
    of the vascular lining
  • treat with tetracycline chloramphenicol

139
4 Types of Rickettsioses
  • 1. epidemic typhus
  • R. prowazekii carried by lice
  • starts with a high fever, chills, headache, rash
  • Brill-Zinsser is a chronic, recurrent form
  • 2. endemic typhus
  • R. typhi, harbored by mice rats
  • occurs sporadically in areas of high flea
    infestation
  • milder symptoms

140
4 Types of Rickettsioses
  • 3. Rocky Mountain spotted fever
  • R. rickettsii zoonosis carried by dog wood
    ticks
  • most cases on eastern seaboard
  • distinct spotted rash

141
4 Types of Rickettsioses
  • 4. Ehrlichia genus
  • contains 2 species of rickettsias
  • tickborne bacteria
  • Most humans recover rapidly
  • 5 chronically ill patients die from disseminated
    infection

142
Coxiella burnetti
  • Q fever
  • intracellular parasite
  • produces an unusual resistant spore
  • harbored by a wide assortment of vertebrates
    arthropods
  • transmitted by air, dust, unpasteurized milk,
    ticks
  • usually inhaled causing pneumonitis, fever,
    hepatitis
  • tetracycline treatment
  • vaccine available

143
Bartonella
  • small gram-negative
  • Fastidious, cultured on blood agar
  • causes
  • trench fever
  • spread by lice
  • cat-scratch disease
  • lymphatic infection associated with a clawing
    injury by cats
  • bacillary angiomatosus in AIDS patients
  • tetracycline, erythromycin rifampin

144
2. Chlamydia
  • obligate intracellular parasites
  • small gram-negative cell wall
  • alternate between 2 stages
  • elementary body
  • small metabolically inactive, extracellular,
    infectious form
  • reticulate body
  • grows within host cell vacuoles

145
Chlamydia trachomatis
  • trachoma
  • attacks the mucous membranes of the eyes,
    genitourinary tract lungs
  • ocular trachoma
  • severe infection, deforms eyelid cornea, may
    cause blindness
  • inclusion conjunctivitis
  • occurs as babies pass through birth canal
  • prevented by prophylaxis
  • STD
  • urethritis, cervicitis, scarring
  • lymphogranuloma venereum
  • disfiguring disease of the external genitalia
    pelvic lymphatics

146
Chlamydia trachomatis
147
Other Chlamydia
  • C. pneumoniae
  • causes an atypical pneumonia
  • serious in asthma patients
  • C. psittaci
  • causes ornithosis
  • zoonosis transmitted to humans from bird vectors
  • highly communicable among all birds
  • pneumonia or flulike infection with fever, lung
    congestion

148
3. Molliculites and Other Cell-Wall-Deficient
Bacteria
  • Called mycoplasmas
  • Naturally lack cell walls
  • highly pleomorphic
  • Require special lipids from host membranes
  • Treated with tetracycline, erthyromycin

149
Mycoplasmas
  • M. pneumoniae
  • primary atypical pneumonia
  • pathogen slowly spreads over interior respiratory
    surfaces
  • causes fever, chest pain and sore throat
  • M. hominis and Ureplasma urealyticum
  • weak sexually transmitted pathogens

150
Bacteria in Dental Disease
  • oral cavity is a complex, dynamic ecosystem
  • contains 400 species
  • dental caries
  • slow progressive infection of irregular areas of
    enamel surface

151
Bacteria in Dental Disease
  • begins with colonization by slime-forming species
  • Streptococcus
  • cross adherence with Actinomyces
  • process forms layer of plaque
  • harbors masses of bacteria which produce acid
    that dissolves enamel
  • If plaque is allowed to stay, secondary invaders
    appear
  • Lactobacillus, Bacteroides, Fusobacterium,
    Porphyromonas, Treponema
  • Acid dissolves tooth enamel

152
Peridontal disease
  • soft tissue disease
  • plaque becomes calcified into calculus above and
    below the gingiva
  • irritates tender gingiva causing inflammation
  • gingivitis
  • pockets between tooth gingiva are invaded by
    bacteria
  • tooth socket may be involved
  • peridontitis
  • tooth may be lost
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