1. The Spirochetes Gram-negative human pathogens
Free living saprobes, or commensals of animals, not primary pathogens
Treponema
Leptospira
Borrelia

2. Typical spirochete

3. Genus Treponema 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. Treponema Pallidum: The Spirochete of Syphilis
Humans are the natural host
Extremely fastidious and sensitive; cannot survive long outside of the host
Sexually transmitted and transplacental

5. Pathogenesis and Host Response
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

8. Primary syphilis lesion, chancre

9. Symptom of secondary syphilis

10. Manifestations of syphilis

11. Congenital syphilis

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

13. Treponema pallidum

14. Nonsyphilitic Treponematoses
Resemble syphilis; rarely transmitted sexually or congenitally; cutaneous and bone diseases endemic to specific regions
Bejel – T. pallidum subspecies endemicum; 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

15. Endemic treponematoses

16. Leptospira and Leptospirosis
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 U.S.

17. Borrelia: Arthropod-Borne Spirochetes
Large, 3-10 coils irregularly spaced
Borrelioses transmitted by arthropod vector
B. hermsii – relapsing fever
B. burgdorferi – Lyme disease

18. B. Hermsii – Relapsing Fever
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

19. Pattern in relapsing fever

20. B. Burgdorferi – Lyme Disease
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
50-70% 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

21. Cycle of Lyme disease

22. Views of Lyme disease skin rash

23. Curviform Gram-Negative Bacteria and Enteric Diseases
Three genera:
Vibrio – comma-shaped rods, single polar flagellum
Campylobacter – short spirals or curved rods; one flagellum
Helicobacter – spirochete with tight spirals and several polar flagella

24. Vibrio Cholera Comma-shaped, possess unique O and H Ags
El Tor biotype: survives longer, more infectious
Infectious dose 108
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

25. Alterations in intestinal function caused by cholera toxin

26. Alterations in intestinal function caused by cholera toxin

27. Pathogens Carried by Seafood
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

28. Diseases of the Campylobacter Vibrios
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

29. Campylobacter Jejuni Enteritis
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

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

31. Helicobacter Pylori: Gastric Pathogen
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 urea into ammonium and bicarbonate

32. The causative agent of stomach ulcers

33. Medically Important Bacteria of Unique Morphology and Biology

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

35. Rickettsia Obligate intracellular parasites Gram-negative cell wall
Among 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

36. Specific Rickettsioses
Epidemic typhus – R. prowazekii carried by lice; starts with a high fever, chills, headache, rash; Brill-Zinsser is a chronic, recurrent form
Endemic typhus – R. typhi, harbored by mice and rats; occurs sporadically in areas of high flea infestation; milder symptoms
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
Ehrlichia genus contains 2 species of rickettsias; tick-borne bacteria cause human monocytic and granulocytic ehrlichiosis

38. Trends in infection for Rocky Mountain spotted fever

39. Transmission cycle in Rocky Mountain spotted fever

40. Rash in RMSF

41. Related to the Rickettsioses
Coxiella burnetti
Bartonella sp.

42. Coxiella Burnetti Causes Q fever Intracellular parasite
Produces an unusual resistant spore
Harbored by a wide assortment of vertebrates and arthropods
Infectious material includes urine, feces, milk, and airborne particles
Usually inhaled causing pneumonitis, fever, hepatitis
Tetracycline treatment
Vaccine available

43. Bartonella Species
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

44. Cat-scratch disease

45. The Chlamydiaceae 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

46. Life cycle of Chlamydia

47. Chlamydia Trachomatis
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

48. The pathology of primary ocular chlamydial infection

49. Diagnosis of chlamydial infection

50. Chlamydophila – A New Genus
Contains members that used to be members of genus Chlamydia
Chlamydophila 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

51. 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
M. pneumoniae – primary atypical pneumonia; pathogen slowly spreads over interior respiratory surfaces, causing fever, chest pain, and sore throat
M. genitalium and Ureplasma urealyticum – weak sexually transmitted pathogens

52. The morphology of mycoplasmas

53. Bacteria That Have Lost Their Cell Walls
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 avium paratuberculosis