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

The Spirochetes Gram negative human pathogens Treponema Leptospira Borrelia

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

Treponema pallidum: The Spirochete of Syphilis 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

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.

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

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

Nonsyphilitic Treponematoses 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

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 US

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

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

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 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

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

Vibrio Cholera Comma-shaped, possess unique O and H Ags Top 7 causes of morbidity and mortality Ingested with food or water 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

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

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

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

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

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 ammonium and bicarbonate into alkaline products that neutralize stomach acid

Medically Important Bacteria of Unique Morphology and Biology

Family Rickettsiaceae 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.

Rickettsia 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.

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; tickborne bacteria cause human monocytic and granulocytic ehrlichiosis

Related to the Rickettsioses Coxiella burnetti Bartonella sp.

Coxiella burnetti 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

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

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

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

Chlamydiophila - A New Genus 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

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. hominis and Ureplasma urealyticum – weak sexually transmitted pathogens

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 paratuberculosi

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

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.

Periodontal Disease 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.