Miscellaneous Bacterial Agents of Disease Chapter 21

spirochetes Gram negative human pathogens Treponema Leptospira Borrella

Treponema thin, coiled cells live in the oral cavity, intestinal tract, & perigenital regions of humans & animals Pathogenic species are strict parasites

Treponema pallidum human is the natural host extremely fastidious & sensitive, cannot survive long outside of the host causes syphilis Primary syphilis: chancre lesion Secondary syphilis: spread throughout the body via blood stream Latent syphilis: obvious symptoms disappear Tertiary syphilis: Hyperimmune response that can affect many systems. (dementia, blindness, heart disease etc. etc.) Congenital syphilis: infection across the placenta-nasal discharge, skin eruptions, bone deformation, nervous system abnormalities treatment: penicillin G

Chancre

Darkfield Microscopy

Leptospira tight, regular individual coils with a bend or hook at one or both ends L. interrogans – causes leptospirosis, a zoonosis bacteria shed in urine; infection occurs by contact; targets kidneys, liver, brain, eyes sudden high fever, chills, headache, muscle aches, conjunctivitis, & vomiting 50-60 cases a year in US

Borrelia large, 3-10 coils Borrelioses transmitted by arthropod vector B. hermsii – tick-borne relapsing fever There also a louse-borne relapsing fever (B. recurrentis) 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, & 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

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

Lyme Disease

Lyme disease

Vibrio cholera comma-shaped One of top 7 causes of morbidity & mortality ingested with food or water infects surface of small intestine, noninvasive cholera toxin causes electrolyte & water loss through secretory diarrhea (“rice-water” stool), resulting dehydration leads to muscle, circulatory, & neurological symptoms treatment: oral rehydration, tetracycline

Cholera in Haiti 1,186 dead from cholera, 19,646 hospitalized (as of November 20th, 2010)

Action of Cholera Toxin Figure 21.25

other Vibrio salt-tolerant inhabitants of coastal waters, associate with marine invertebrates Vibrio parahaemolyticus –gastroenteritis from raw seafood Vibrio vulnificus gastroenteritis from raw oysters nasty skin/tissue infections of cuts and scratches

Campylobacter jejuni important cause of bacterial gastroenteritis transmitted by beverages & food (poultry most common) 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 that is self-limiting heat-labile enterotoxin

Campylobacter jejuni

Helicobacter pylori Curved cells discovered in 1979 in stomach biopsied specimens Slightly helical, highly motile bacterium that colonizes the stomach of its hosts Causes gastritis and most (if not all) peptic ulcers. (Also a big risk factor for stomach cancer)

H. pylori and Peptic Ulcers Figure 21.27.1

H. pylori and Peptic Ulcers Figure 21.27.2

H. pylori and Peptic Ulcers Figure 21.27.3

Diagnosis, Treatment, and Prevention Presence of H. pylori can be demonstrated by a positive urease test Biochemical tests provide a definitive identification Treatment Antimicrobial drugs are used in combination with drugs that inhibit acid production Prevention Prevention involves good hygiene, adequate sewage treatment, water purification, and proper food handling

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 – vasculitis, vascular leakage & thrombosis treat with tetracycline & chloramphenicol

Types of rickettsioses epidemic typhus – R. prowazekii carried by lice; starts with a high fever, chills, headache, rash; May have a chronic, recurrent form endemic typhus (murine typhus) – R. typhi, harbored by mice & rats; occurs sporadically in areas of high flea infestation; milder symptoms Rocky Mountain spotted fever – R. rickettsii zoonosis carried by dog & wood ticks; most cases on eastern seaboard; distinct spotted rash; may damage heart & CNS Ehrlichia genus: human monocytic ehrlichiosis Anaplasma genus: anaplasmosis

Rocky Mountain Spotted Fever

Rocky Mountain Spotted Fever Rickettsia rickettsii

Coxiella burnetti causes 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

Coxiella burnetti

Bartonella small gram-negative, fastidious, cultured on blood agar Bartonella-caused diseases trench fever, spread by lice cat-scratch disease, a lymphatic infection associated with a clawing injury by cats. Organism carried by 40% of cats Most infections localized and resolve a a couple weeks bacillary angiomatosus in AIDS patients tetracycline, erythromycin & rifampin

Cat-scratch disease Bartonella henselae

Chlamydia obligate intracellular parasites small gram-negative cell wall C. 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

Chlamydia trachomatis human reservoir 2 strains trachoma strain– attacks the mucous membranes of the eyes, genitourinary tract & lungs ocular trachoma – uncommon in U.S. but common in Africa and Asia. Severe infection, deforms eyelid & cornea, may cause blindness inclusion conjunctivitis – occurs as babies pass through birth canal; prevented by prophylaxis STD – urethritis, cervicitis, salpingitis (PID),infertility, scarring lymphogranuloma venereum strain– disfiguring disease of the external genitalia & pelvic lymphatics

Chlamydia trachomatis Lymphogranuloma venereum lesion Trachoma

Mycoplasma naturally lack cell walls, highly pleomorphic treated with tetracycline, erthyromycin M. pneumoniae – primary atypical pneumonia; pathogen slowly spreads over interior respiratory surfaces, causing fever, chest pain & sore throat. M. hominis & Ureplasma urealyticum – weak sexually transmitted pathogens

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 & cross adherence with Actinomyces process forms layer of thick, adherent material (plaque) that 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

Thin mucous coating of salivary proteins Streptococcus mutans Secondary invaders

Peridontal 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 & gingiva are invaded by bacteria (spirochetes & gram-negative bacilli) tooth socket may be involved (peridontitis) tooth may be lost