C H A P T E R © 2014 Pearson Education, Inc. PowerPoint ® Lecture Presentations prepared by Mindy Miller-Kittrell, North Carolina State University Rickettsias, Chlamydias, Spirochetes, and Vibrios 21

Miscellanous Bacterial Pathogens Traditionally discussed separately due to their unique features Four Groups: 1. Slightly curved rods called vibrios 2. Spiral shaped bacteria called spirochetes 3. Wall-less mycoplasmas 4. Obligate intracellular rickettsias & chlamydias

Vibrio cholerae Description  curved gram negative rod  Found in freshwater and marine environments worldwide; most pathogens multiply in shellfish  Certain strains cause Cholera Figure Pathogenicity  cholera exotoxin Transmission  Ingesting contaminated food & water  raw oysters, shellfish  Requires large inoculum to survive acidic stomach environment

Copyright © 2007 Pearson Education, Inc. publishing as Benjamin Cummings Action of Cholera Toxin Figure

Cholera Symptoms extensive watery diarrhea leading to Rice-water stools Dehydration & electrolyte imbalance can lead to muscle cramps, shock, death 60% mortality in untreated patients; death can be in less than 48 hours Treatment Rapid fluid & electrolyte replacement prior to hypovolemic shock Doxycyline is drug of choice Prevention sanitation; water treatment O1 strain vaccine has short lived immunity Prophylactic antibiotics given to travelers to endemic areas

Vibrio cholerae – cholera beds i-one-year-later-the-cholera-crisis/cholera-bed/ i-one-year-later-the-cholera-crisis/cholera-bed/ (animated story)

Pathogenic Gram-Negative Vibrios Vibrio Other diseases of Vibrio V. parahaemolyticus  Results from ingestion of shellfish  Causes cholera-like gastroenteritis V. vulnificus  Septicemia  Due to consumption of contaminated shellfish  Wound infections  Due to washing wounds with contaminated seawater  Infections can be fatal if untreated

Campylobacter jejuni Likely the most common cause of gastroenteritis in the United States Many animals serve as reservoirs for the bacteria Humans become infected by consuming contaminated food, milk, or water Poultry is the most common source of infection Infections produce bloody and frequent diarrhea that is self-limiting Spread of the bacteria can be reduced by proper food handling and preparation

Helicobacter pylori Description Slightly helical, highly motile bacterium that colonizes the stomach of its hosts Causes gastritis and most (if not all) peptic ulcers Pathogenicity Protein to inhibit acid production Urease – digests urea; neutralizes stomach acid Flagella, adhesins Antiphagocytic enzymes Figure 21.26

H. pylori and Peptic Ulcers Figure Overview

Transmission Contamination in well water or contaminated fomites or from feces on the hands Complication – increased risk of stomach cancer Treatment Combination of 2 or 3 antimicrobial drugs along with drugs that inhibit acid production Prevention good personal hygiene, adequate sewage treatment, water purification, and proper food handling Helicobacter pylori

Thin, tightly coiled, helically shaped bacteria Moves in a corkscrew fashion through its environment This movement is thought to enable pathogenic spirochetes to burrow through their hosts’ tissues Three genera cause human disease Treponema, Borrelia, and Leptospira SPIROCHETES

Treponema pallidum Figure Disease – Syphilis Description Obligate parasite of humans only Cannot survive environment Pathogenicity Glycocalyx Hyaluronidase Adhesion proteins Corkscrew motility

Transmission Occurs worldwide Almost solely via sexual contact Infected mother to her fetus Incidence greatly reduced since discovery of antibiotics Syphilis Figure Overview

Symptoms Primary stage: Painless lesion (chancre) at site of infection. Center of chancre infectious; lasts 3-6 weeks Secondary: widespread rash, sore throat, headache, fever, malaise, myalgia, & lymphadenopathy Latent period: asymptomatic, can last 30 yrs or more; most cases do not advance if treated with antibiotics Tertiary: Painless lesions called gummas on organs, skin, nerves, brain Syphilis Figure Overview Pictures of symptoms:

Congenital Syphilis Treponema pallidum crosses the placenta Death of fetus if crosses during primary or secondary stage Mental retardation or malformation of many fetal organs if crosses during latent stage Newborns with latent infection develop skin lesions in first two years of life Syphilis

Congenital Syphilis

Diagnosis Primary, secondary, and congenital can be readily diagnosed with antibody tests against bacterial antigens Tertiary syphilis is difficult to diagnose; mimics other disease Treatment Penicillin is the drug of choice except with tertiary syphilis which is a hyperimmune response and not an active infection Prevention Abstinence, safe sex Syphilis

Lightly staining, Gram-negative spirochetes Cause two diseases in humans Lyme disease Borrelia burgdorferi Relapsing fever Borrelia recurrentis Borrelia

Borrelia burgdorferi = causative agent Bacteria are transmitted to humans via a tick bite Hard ticks of the genus Ixodes are the vectors of Lyme disease First discovered in 1975 in Lyme, Connecticut due to high incidence of childhood rheumatoid arthritis Lyme Disease

© 2014 Pearson Education, Inc. Figure The occurrence of Lyme disease in the United States.

© 2014 Pearson Education, Inc. Figure The life cycle of the deer tick Ixodes and its role as the vector of Lyme disease.

Lyme Disease Symptoms - Three phases 1. “bull’s eye” rash at site of infection 2. Neurological symptoms and cardiac dysfunction in 10% of patients 3. Severe arthritis that can last for years Figure Treatment Doxycycline or penicillin in first stage later stages symptoms primarily immune response Prevention take precautions to avoid ticks

The increase of cases is a result of humans coming in closer association with deer ticks infected with Borrelia Treatment Antimicrobial drugs can effectively treat the first stage of Lyme disease Treatment of later stages is difficult because symptoms primarily result from the immune response rather than the presence of bacteria Prevention is best achieved by taking precautions to avoid ticks Lyme Disease

Relapsing fever Borrelia recurrentis – c ausative agent Two types of relapsing fever: Louse-borne relapsing fever Transmitted to humans by the human body louse; seen in Africa and South America Endemic relapsing fever Several Borrelia species can cause this disease Transmitted to humans by soft ticks

Relapsing fever  Symptoms  Recurring episodes of fever and septicemia separated by symptom-free intervals  Pattern results from the body’s repeated efforts to remove the spirochetes (which continually change their antigenic surface components)

Relapsing fever Diagnosis Observation of the spirochetes is the primary method of diagnosis Treatment Successful treatment is with antimicrobial drugs Prevention avoidance of ticks and lice, good personal hygiene, and use of repellent chemicals

© 2014 Pearson Education, Inc. First antigenic challenge First antibody response Second antigenic challenge Second antibody response Third antigenic challenge Third antibody response Figure The time course of recurring episodes of fever in relapsing fevers.

Leptospira interrogans Disease: Causes the zoonotic disease, leptospirosis Normally found in numerous wild and domestic animals Transmission Through direct contact with the urine of infected animals or contaminated streams, lakes, or moist soil Leptospira gain initial access via invisible cuts and abrasions in the skin and mucous membranes Disseminates throughout the body and found only in the kidneys and are excreted in urine Eradication of the disease is impractical due to the spirochete’s many animal reservoirs

Characterisitcs of the Smallest Microbes

Description:  Smallest free-living bacteria  Lack cell walls  Sterols in cell membrane for strength & rigidity  Fastidious – need organic growth factors from host or media  produce very small colonies giving a “fried egg” appearance on media Mycoplasma pneumoniae Figure 21.1 Figure 11.15

Virulence Factor: Adhesive protein – attaches to and destroy ciliated cells lining respiratory tract Disease: Primary Atypical Pneumonia also called “walking pneumonia” Symptoms: Fever, headache, sore throat, malaise, dry hacking cough which can persist for more than 3 weeks Usually not severe enough to cause hospitalization or death Mycoplasma pneumoniae

Transmission: Spread person to person in close contact via nasal secretions Treatment: tetracycline or erythromycin (NOT penicillin ) Frequent hand antisepsis, avoid contaminated fomites and reduce aerosol Diagnosis: is difficult because mycoplasmas are small and grow slowly Prevention: can be difficult because patients can be infective for long periods of time without signs or symptoms Mycoplasma pneumoniae

M. hominis, M. genitalium, and Ureaplasma urealyticum M. genitalium and U. urealyticum cause inflammation of the urethra M. hominis can cause inflammation of the kidneys, postpartum fever, and pelvic inflammatory disease in women Often colonize in the urinary and genital tracts of newborn girls Abstinence and safe sex can help prevent the spread of these sexually transmitted organisms Other Mycoplasma

Characteristics of Rickettsia

Rickettsia rickettsii Figure 21.3 Description: Obligate intracellular bacteria even though they have functional genes for protein synthesis, ATP production, and reproduction Extremely small (not much bigger than a smallpox virus) Transmission: Through a tick bite

Rickettsia rickettsii Disease: Rocky Mountain Spotted Fever Common in southeastern USA Fever, headache, chills, muscle pain, nausea, & vomiting. Figure 21.4 Figure % spotted, non-itchy rash 50% develop petechiae Complications – respiratory tract, CNS, GI & renal system 5% mortality w/treatment

Rickettsia rickettsii Treatment: Doxycyline, tetracycline, or chloramphenicol Prevention: Avoid tick infested areas especially in spring & summer Wear tight-fitting clothing Use tick repellent

Chlamydia Description:  Obligate intracellular parasites  Two membranes but NO cell wall  Unique life cycle within host  Elementary body – tiny cocci; infective  Reticulate body – pleomorphic; obligate intracellular form

© 2014 Pearson Education, Inc. Elementary body (EB) attaches to receptor on host cell (0 hour). EBs are released from host cell (40 hours). EB triggers its own endocytosis by host cell. Most RBs convert back into EBs (21 hours). Vesicle EB inside endocytic vesicle. EB converts into reticulate body (RB) within vesicle (10 hours). RB divides rapidly, resulting in multiple RBs. The vesicle is now called an inclusion body. Inclusion body RBEB Inclusion body Figure 21.6 Development of chlamydias.

Chlamydia Three Species cause human disease:  Chlamydia trachomatis  Sexually transmitted disease  Ocular disease, Trachoma – leading cause of nontraumatic blindness  Chlamydia pneumoniae  10% of Community acquired pneumonia in US  5% of Bronchitis & sinusitis in US  Chlamydia psittaci  Ornithosis - flulike symptoms  Transmitted to humans from birds

Chlamydia trachomatis  Transmission  Infect the conjunctiva and various mucous membranes  Enters the body through abrasions and lacerations  Clinical manifestations result from the destruction of infected cells at the infection site and from the resulting inflammatory response

Chlamydia trachomatis  Causes two main types of disease  Sexually transmitted diseases  One of the most common sexually transmitted disease in the United States  Ocular disease called trachoma  Occurs particularly in children  Endemic in crowded, poor communities with poor hygiene, inadequate sanitation, and inferior medical care

Chlamydia trachomatis Sexually Transmitted:  Most common STI in US  Women under 20 more susceptible  85% asymptomatic in women; 75% symptomatic in men Symptoms:  Small, painless genital lesions that heal rapidly  Women can develop pelvic inflammatory disease if reinfected 

Chlamydia trachomatis Complications Proctitis – inflammation of rectum Pelvic Inflammatory Disease (PID) in women May be transmitted to newborn's eyes causing Trachoma Treatment:  Doxycycline for genital infections Erythromycin or sulfonamides for pregnant women Prevention: Abstinence or faithful mutual monogamy Condoms provide some protection

Chlamydia trachomatis Disease – Ocular Trachoma Symptoms  Conjuctivitis, inflammation, discharge  Can cause blindness if untreated Transmission  From mother to baby during birth  Eye to eye via droplets, contaminated fomites, hands, flies  Endemic in poor, crowded communities with inadequate sanitation.

Chlamydia trachomatis

 Diagnosis  Demonstration of the bacteria inside cells from the site of infection  Treatment  Antibiotics can be administered for genital and ocular infections  Surgical correction of eyelid deformities from trachoma may prevent blindness

Characteristics of the Smallest Microbes Table 21.2