Chapter Outline
21.1 The Spirochetes
A. Genus Treponema
1. General characteristics
a. Helical, flexible bacteria, 8-12 regular spirals
b. Motile-periplasmic flagella
c. Many obligate parasites
2. Laboratory procedures
a. Direct observation in tissues and blood
b. Dark field microscopy
c. Cannot be cultured in artificial media
B. Treponemes: members of the Genus Treponema
1. Treponema pallidum: syphilis
a. Epidemiology and virulence factors
b. Pathogenesis
i. Primary syphilis-at site of infection a chancre occurs
ii. Secondary syphilis
-fever, headache, and sore throat
-red or brown rash
- primary and secondary stages are communicable
-spirochete in tissues
iii. Latency and tertiary syphilis
-noncommunicable
-gummas
-life threatening cardiovascular and neurological damage
c. Congenital syphilis
i. Transplacental acquisition
ii. Nasal discharge, skin eruptions, Hutchinson’s teeth
d. Clinical and laboratory diagnosis
i. Dark-field microscopy of suspected lesions
ii. Direct immunofluorescence staining
iii. Screening for high risk populations
-RPR, VDRL
iv. More specific tests( serology tests)
- MHA-TP
- FTA-ABS
e. Treatment and prevention
i. Penicillin G
ii. detection and treatment of sexual contacts
2. Nonsyphilitic Treponematoses- tropics and subtropics
a. Bejel-Treponema pallidum subspecies endemicum
b. Yaws-T. pallidum subspecies pertenue
c. Pinta-T. pallidum subspecies carateum
C. Leptospira interrogans
1. Zoonosis acquired by contact with infected urine of wild/domestic animals
2. Multiplies in blood and spinal fluid
3. Treatment- antimicrobial drugs
D. Borrelia: irregular spirochetes, vector-borne, mostly ticks
1. Relapsing fever- B.hermsii and B. recurrentis
a. Pathogenesis-changing antigens so difficult for immune system
b. 10-12 days fever recurs
c. Treatment with antimicrobial drugs, prevention-improve hygiene
2. Borrelia burgdorferi –Lyme disease
a. A collection of symptoms, endemic in several parts of U.S.
b. Zoonosis carried by mice, spread by tick(Ixodex) that lives on deer
and mice
c. Tick bite can lead to erythema migrans, fever and if untreated-cardiac,
neurologic and arthritic symptoms
d. Treatment-antimicrobial drugs, avoid tick infested areas
21.2 Curviform Gram-Negative Bacteria and Enteric Diseases
A. Vibrios-short spirals, curved with polar flagella
1. Vibrio cholerae
a. Epidemiology of cholera-contaminated food and water
b. Pathogenesis-infects small intestine, produces cholera toxin-causes
electrolyte loss and secretory diarrhea
c. Dehydration leads to muscle, circulatory and neurological symptoms
d. Treatment-oral rehydration therapy, vaccine available
2. Vibrio parahaemolyticus and Vibrio vulnificus: pathogens carried by seafood
a. V. parahaemolyticus- Gastroenteritis
B. Campylobacter species
a. Campylobacter jejuni- severe gastroenteritis from contaminated meat,
water, and eggs
b. C. fetus-infects pregnant women, can cause fatal septicemia in
neonates
C. Helicobacter pylori: helical shaped, lives in stomach lining
a. Causes gastric ulcers and gastritis
b. Antimicrobial drugs and antacids
21.3 Medically Important Bacteria of Unique Morphology and Biology
A. Family Rickettsiaceae- tiny, gm- rods, metabolic and intracellular parasites,
zoonoses spread by arthropod vectors
1. Rickettsia prowazekii- epidemic typhus
a. Epidemiology-lice
b. High fever, chills, headache and rash
c. Treatment-antimicrobial drugs
2. Rickettsia typhi –endemic typhus
a. Mice and rats, fleas transmit
b. Symptoms and treatment like epidemic form just milder
3. Rickettsia rickettsii- Rocky Mountain Spotted Fever
a. Zoonosis- dog and wood ticks(Dermacentor)
b. Spotted, migratory rash, heart damage, CNS
c. Antimicrobial drugs and avoid ticks
4. Ehrlichia and Anaplasmaa. Tick borne
b. Monocytic erlichosis and human anaplasmosis-acute, febrile
infections
B. Coxiella and Bartonella: Other Vector-Borne Pathogens
1. Q Fever - Coxiella burnetii
a. Zoonosis, transmitted by air, dust, unpasteurized milk, ticks
b. Pneumonitis, fever, hepatitis
c. Spontaneous resolution, antimicrobial drugs, vaccine
2. Cat-Scratch and Trench Fever -Bartonella henselae
a. Lice-trench fever; scratch or bites by cats-cat scratch fever
b. Spontaneous resolution, antimicrobial drugs
C . The Chlamydiaceae- tiny, gram-negative coccobacilli that are obligate
intracellular parasites of animals, elementary body and intracellular reticulate body
phases
1. Chlamydia trachomatis
a. Ocular trachoma-severe infection, blindness possible
b. Conjunctivitis- occurs in babies after contact in birth canal
c. Sexually transmitted chlamydial diseases
i. Nongonococcal urethritis (NUG) in men
ii. Cervicitis, and Pelvic Inflammatory Disease (PID) in
women-infertility, scarring and disfiguring
lymphogranuloma venereum
d. Identification, Treatment, and Prevention
2. Chlamydophila
a. Chlamydophila pneumonia-respiratory infection in young adults and
asthmatics
b. Chlamydophila psittaci- ornithosis-respiratory, transmitted by birds,
system complications if untreated
21.4 Mollicutes and Other Cell-Wall-Deficient Bacteria
A. Mycoplasma- naturally lack cell walls, pleomorphic, not obligate parasites-do
require lipids from host membranes, treated with tetracycline and erythromycin
1. Mycoplasma pneumoniae - atypical pneumonia
a. Slow spread over respiratory system
b. Fever, chest pain and sore throat
2. L forms- normally have cell walls but lost with time and antibiotic therapy
a. Some normal flora
b. May be involved in chronic diseases
21.5 Bacteria in Dental Disease
A. Structure of teeth and associated tissues
1. Hard-tissue disease: dental caries
a. Slime forming species of Streptococcus, Actinomyces and other
bacteria
b. Plaque- layer of thick adherent material
c. Dental caries-acids dissolve enamel causing breakdown
B. Soft-tissue and periodontal disease
a. Calculus-mineralized plaque on the root of the tooth
b. Gingivitis-inflammatory reaction to calculus
c. Periodontitis-tooth socket involved and possible loss of tooth
d. Necrotizing Ulcerative Gingivitis (NUG)
C. Factors in dental disease
a. Nutrition and eating patterns-high sucrose diet
b. Anatomical, physiological, genetic factors
c. Prevention-brushing, flossing, dental visits