Lecture PowerPoint to accompany
Sixth Edition
Talaro
Chapter 21
Miscellaneous Bacterial
Agents of Disease
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

Gram negative human pathogens
•
Treponema
•
Leptospira
•
Borrelia
2

3

• Thin, regular, coiled cells
• Live in the oral cavity, intestinal tract, and perigenital regions of humans and animals
• Pathogens are strict parasites with complex growth requirements.
• Require live cells for cultivation
4

• Human is the natural host
• Extremely fastidious and sensitive; cannot survive long outside of the host
• Sexually transmitted and transplacental
• Infectious dose is 57 organisms
5

• Spirochete binds to epithelium (mucous membrane or abraded skin), multiplies, and penetrates capillaries.
• Moves into circulation and multiplies
• Untreated syphilis marked by 3 clinical stages:
– primary, secondary, tertiary
• Spirochete appears in lesions and blood during first 2 stages - communicable.
6

• 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
• Tertiary syphilis – about 30% of infections enter in tertiary stage; can last for 20 years or longer; numerous pathologic complications occur in susceptible tissues and organs
– neural, cardiovascular symptoms, gummas develop
• Congenital syphilis – nasal discharge, skin eruptions, bone deformation, nervous system abnormalities
7

• Stages of syphilis mimic other diseases.
• Consider symptoms, history, microscopic and serological testing
– RPR, VDRL, FTA-ABS
• Treatment: penicillin G
8

9

• Resemble syphilis; rarely transmitted sexually or congenitally; cutaneous and bone diseases endemic to specific regions
• Bejel – T.pallidum subspecies endenicum; deforming childhood infection of the mouth, nasal cavity, body, and hands
• Yaws – T.pallidum subspecies pertenue ; invasion of skin cut, causing a primary ulcer that seeds a second crop of lesions
• Pinta – T. carateum; superficial skin lesion that depigments and scars the skin
10

• Tight, regular individual coils with a bend or hook at one or both ends
•
L. biflexa
– harmless, free-living saprobe
•
L. interrogans
– causes leptospirosis, a zoonosis
– bacteria shed in urine; infection occurs by contact with contaminated urine; targets kidneys, liver, brain, eyes
– sudden high fever, chills, headache, muscle aches, conjunctivitis, and vomiting
– Long term infections may affect kidneys and liver.
– 50-60 cases a year in US
11

• Large, 3-10 coils irregularly spaced
• Borrelioses transmitted by arthropod vector
•
B. hermsii - relapsing fever
•
B. burgdorferi - Lyme disease
12

• Mammalian reservoirs –squirrels, chipmunks, wild rodents
• Tick-borne
• After 2-15-day incubation, patients have high fever, shaking, chills, headache, and fatigue.
• Nausea, vomiting, muscle aches, abdominal pain; extensive damage to liver, spleen, heart, kidneys, and cranial nerves
• Parasite changes and immune system tries to control it- recurrent relapses.
• tetracycline
13

14

• Carried by white-footed mouse, transmitted by Ixodes ticks
• Complex 2-year cycle involving mice and deer
• Nonfatal, slowly progressive syndrome that mimics neuromuscular and rheumatoid conditions
• 70% get bull’s eye rash
• Fever, headache, stiff neck, and dizziness
• If untreated can progress to cardiac and neurological symptoms, polyarthritis
• Tetracycline, amoxicillin
• Vaccine for dogs, human vaccine discontinued
• Insect repellant containing DEET
15

16

17

Three genera:
1. Vibrio
– comma-shaped rods, single polar flagellum
2. Campylobacter
– short spirals or vibrios; one or more flagella
3. Helicobacter
– spirochete with tight spirals and endoflagella
18

• Comma-shaped, possess unique O and H Ags
• Top 7 causes of morbidity and mortality
• Ingested with food or water
• Infectious dose 10 8
• Infects mucous barrier of small intestine, noninvasive
• Cholera toxin causes electrolyte and water loss through secretory diarrhea, “rice water stool”; resulting dehydration leads to muscle, circulatory, and neurological symptoms.
• Treatment: oral rehydration, tetracycline
• Vaccine available
19

20

• Salt-tolerant inhabitants of coastal waters, associate with marine invertebrates
•
Vibrio parahaemolyticus – gastroenteritis from raw seafood; symptoms similar to cholera
•
Vibrio vulnificus gastroenteritis from raw oysters; serious complications in persons with diabetes or liver disease
• Treatment – fluid and electrolyte replacement; occasionally antimicrobials
21

• Campylobacters – slender, curved or spiral bacilli, often S-shaped or gull-winged pairs
• Polar flagella
• Common residents of the intestinal tract, genitourinary tract, the oral cavity of birds and mammals
• Most important:
–
Campylobacter jejuni
– C. fetus
22

• Important cause of bacterial gastroenteritis
• Transmitted by beverages and food
• Reach mucosa at the last segment of small intestine near colon; adhere, burrow through mucus and multiply
• Heat-labile enterotoxin CJT stimulates a secretory diarrhea like that of cholera.
• Symptoms of headache, fever, abdominal pain, bloody or watery diarrhea
• Treatment with rehydration and electrolyte balance therapy
23

•
Campylobacter fetus
– opportunistic pathogen that infects debilitated persons or women late in pregnancy
• Meningitis, pneumonia, arthritis, fatal septicemia in the newborn
24

• Curved cells discovered in 1979 in stomach biopsied specimens
• Causes 90% of stomach and duodenal ulcers; apparent cofactor in stomach cancer
• People with type O blood have a 1.5-2X higher rate of ulcers.
• Produces urease which converts ammonium and bicarbonate into alkaline products that neutralize stomach acid
25

26

• Contains about 23 species of pathogens, mainly in the genus Rickettsia
• Cause diseases caused rickettsioses
• All are intracellular parasites requiring live cells for cultivation.
• Spend part of their life cycle in arthropod vectors
• Rickettsioses are important emerging diseases.
27

• Obligate intracellular parasites
• Gram-negative cell wall
• Smong the smallest bacteria
• Nonmotile pleomorphic rods or coccobacilli
• Ticks, fleas and lice are involved in their life cycle.
• Bacteria enter endothelial cells and cause necrosis of the vascular lining – vasculitis, vascular leakage and thrombosis.
• Treat with tetracycline and chloramphenicol.
28

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 and rats; occurs sporadically in areas of high flea infestation; milder symptoms
3. Rocky Mountain spotted fever – R. rickettsii zoonosis carried by dog and wood ticks; most cases in
Southeast and on eastern seaboard; distinct spotted rash; may damage heart and CNS
4. Ehrlichia genus contains 2 species of rickettsias; tickborne bacteria cause human monocytic and granulocytic ehrlichiosis
29

30

31

•
Coxiella burnetti
•
Bartonella sp.
32

• Causes Q fever
• Intracellular parasite
• Produces an unusual resistant spore
• Harbored by a wide assortment of vertebrates and arthropods
• Transmitted by air, dust, unpasteurized milk, ticks
• Usually inhaled causing pneumonitis, fever, hepatitis
• Tetracycline treatment
• Vaccine available
33

• Small Gram-negative, fastidious, cultured on blood agar
• Cause:
– trench fever, spread by lice
– cat-scratch disease, a lymphatic infection associated with a clawing injury by cats
– bacillary angiomatosus in AIDS patients
• Tetracycline, erythromycin and rifampin
34

• Obligate intracellular parasites
• Small, Gram-negative cell wall
• Alternate between 2 stages:
– elementary body – small metabolically inactive, extracellular, infectious form released by the infected host
– reticulate body – noninfectious, actively dividing form, grows within host cell vacuoles
35

36

• Human reservoir
• 2 strains
• Trachoma – attacks the mucous membranes of the eyes, genitourinary tract and lungs
– ocular trachoma – severe infection, deforms eyelid and cornea, may cause blindness
– inclusion conjunctivitis – occurs as baby passes through birth canal; prevented by prophylaxis
– STD – second most prevalent STD; urethritis, cervicitis, salpingitis (PID), infertility, scarring
• Lymphogranuloma venereum – disfiguring disease of the external genitalia and pelvic lymphatics
37

• Contains members that used to be members of genus Chlamydia
•
Chlamydiophila pneumoniae
– causes an atypical pneumonia that is serious in asthma patients
•
C. psittaci
– causes ornithosis, a zoonosis transmitted to humans from bird vectors; highly communicable among all birds; pneumonia or flulike infection with fever, lung congestion
38

• Called mycoplasmas
• Naturally lack cell walls, highly pleomorphic
• Require special lipids from host membranes
• Treated with tetracycline, erthyromycin
•
M. pneumoniae
– primary atypical pneumonia; pathogen slowly spreads over interior respiratory surfaces, causing fever, chest pain and sore throat.
• M. hominis and Ureplasma urealyticum – weak sexually transmitted pathogens
39

40

• Exposure to certain drugs or enzymes can result in cell wall-deficient bacteria called
L forms or L-phase.
• Induced or occur spontaneously
• May be involved in some chronic diseases
– L- phase variants of group A streptococci,
Proteus , and
Corynebacterium , Mycobacterium paratuberculosi
41

•
Oral cavity is a complex, dynamic ecosystem, containing 400 species.
•
Dental caries – slow progressive infection of irregular areas of enamel surface
1. Begins with colonization by slime-forming species of Streptococcus and cross adherence with
Actinomyces
2. Process forms layer of thick, adherent material
(plaque) that harbors masses of bacteria which produce acid that dissolves enamel
42

3. If plaque is allowed to stay, secondary invaders appear – Lactobacillus, Bacteroides,
Fusobacterium, Porphyromonas, Treponema.
4. Acid dissolves tooth enamel leading to caries and tooth damage.
43

44

45

• Soft tissue disease
• When plaque becomes calcified into calculus above and below the gingiva
• This irritates tender gingiva causing inflammation
– gingivitis.
• Pockets between tooth and gingiva are invaded by bacteria (spirochetes and Gram-negative bacilli).
• Tooth socket may be involved (peridontitis).
• Tooth may be lost.
46