C H A P T E R © 2014 Pearson Education, Inc. PowerPoint ® Lecture Presentations prepared by Mindy Miller-Kittrell, North Carolina State University Pathogenic Gram-Positive Rods 19

Two Groups: Endospore-forming Bacillus – aerobic; found in soil Clostridium - anaerobes; found in soil, water, sewage & GI tract of animals & humans Nonendospore-forming Corynebacterium Many species are normal flora of mucus membranes Listeria monocytogenes Found in soil and water Some animals have bacteria Gram-Positive Bacilli

Bacillus anthracis Description Gram-positive rods, Endospore-forming Aerobic Pathogenicity (virulence factors) Capsule Anthrax toxin Figure

Transmission Humans contract disease primarily from infected animal by-products Three routes of transmission 1. Inhalation of spores 2. Inoculation of spores into the body through a break in the skin 3. Ingestion of spores Bacillus anthracis

Diseases – clinical manifestations Gastrointestinal anthrax – rare in humans but common in animals intestinal hemorrhaging and eventually death Cutaneous anthrax -Most common Ulcer with black necrotic center (eschar) 20% mortality if toxemia develops Inhalation anthrax – Woolsorter’s Disease Inhaled spores germinate in the lungs and secrete toxins into the bloodstream Early signs – fatigue, malaise, fever aches Late stage – toxemia, difficulty breathing; High mortality rate Characteristic black eschar of cutaneous Bacillus anthracis

Diagnosis – presence of large, nonmotile, Gram-positive bacilli in clinical samples of the lungs or skin Treatment – Penicillin, doxycycline, ciprofloxacin Antitoxin Prevention – Control the disease in animals Via vaccination & proper disposal of carcasses Human anthrax vaccine requires multiple doses and boosters Bacillus anthracis

Clostridium perfringens Description gram positive, endospore forming anaerobic rod normal flora of the intestinal tract Pathogenicity (virulence factors) Produces 11 toxins that cause irreversible damage by: Lysing RBC & WBC Killing host cells Increasing vascular permeability Reducing blood pressure

Diseases – typically non-invasive Mild food poisoning from ingestion of contaminated meat abdominal cramps, watery diarrhea; lasts 24 hrs; NO fever, nausea or vomiting Treatment - typically self-limiting as pathogens & toxins are eliminated through watery stool Prevention – refrigerate foods to prevent toxin formation; thoroughly reheat foods to destroy toxins Clostridium perfringens

Gas Gangrene – trauma introduces endospores into body Toxins induce swelling & tissue death Myonecrosis – death of muscle and connective tissue Foul smelling gases produced by growing bacterial waste Shock, kidney failure & death often within one week of infection Clostridium perfringens Figure Treatment – fatal without treatment; 40% mortality with treatment Penicillin & antitoxins amputation of necrotic tissue; hyperbaric chamber saturates tissue with oxygen Prevention - prompt wound cleaning

Normal intestinal flora in 3-5% of adults Pathogenicity (virulence factors) Toxin A & Toxin B Diseases Opportunistic pathogen in patients treated with long- term broad-spectrum antimicrobial drugs Minor infections result in a self-limiting explosive diarrhea Serious cases can cause pseudomembranous colitis resulting in perforation of the colon Clostridium difficile 101_385953_7.pdf

Diagnosis by isolating the organism from feces by demonstrating the presence of toxins via immunoassay Minor infections are usually resolved by discontinuing use of the antimicrobial drug Serious cases are treated with antibiotics: Vancomycin Fecal transplant Proper hygiene is critical for limiting nosocomial infections Clostridium difficile

Clostridium botulinum Description - gram positive anaerobic spore forming bacillus Pathogenicity (virulence factors) –7 antigenic types (desginated A-G) of botulism toxin (Botox) –Extremely potent; among deadliest toxins known –Toxin inhibits release of neurotransmitter Figure Overview

Disease – Botulism –Infant botulism ingestion of endospores that germinate and colonize GI tract because lack sufficient normal flora constipation and “failure to thrive”; paralysis and death are rare al/faq.php?printable=1 –Wound botulism 4 or more days following contamination of wound by endospores symptoms are the same as with food-borne botulism Clostridium botulinum

Disease – Botulism Intoxication caused by the botulism toxin; not an infection Food-borne botulism - –ingest toxin in canned foods or preserved fish –weakness, dizziness, blurred vision, dry mouth, dilated pupils, constipation & abdominal pain –can lead to progressive paralysis Clostridium botulinum

Treatment Repeated washing of the intestinal tract to remove Clostridium large doses of antitoxin will neutralize circulating neurotoxin supportive care infant botulism - antimicrobials drugs to kill bacteria Prevention Proper canning techniques Prevent germination of endospores in food via refrigeration or acidic environment Toxin is destroyed by heating (80 o C 20 min.) Honey source of endospores so do not feed to infants under age 1 Clostridium botulinum

Clostridium tetani Pathogenicity (virulence factors) potent tetanus toxin (neurotoxin) Transmission via puncture into tissue from soil contaminated with animal feces IV drug users Figure Description gram positive anaerobic terminal endospore- forming bacillus found in soil, dust & GI tract of animals & humans

Figure Overview Clostridium tetani Disease Tetanus (lockjaw) Typically starts with tight jaw & neck muscles Neurotoxin blocks relaxation pathway Hyperactive spasms & muscle contractions Respiratory spasms – inability to exhale leads to death

Causes irreversible damage at each synapse 50% mortality rate; > 90% mortality in neonatal tetanus Clostridium tetani Figure Treatment Clean wounds to remove endospores Antitoxin - tetanus immunoglobulin Antibiotics – penicillin Prevention DPT vaccine (Toxoid)

Listeria monocytogenes Description - Gram-positive non-spore- forming bacillus Found in soil, water, mammals, birds, fish, and insects Enters body in contaminated food and drink Pathogenicity (virulence factors) Listeria produces no toxins or enzymes Virulence is directly related to the bacteria’s ability to live within cells

Figure Listeria monocytogenes

Diseases Meningitis that can lead to death in pregnant women, fetuses, newborns, the elderly & immunocompromized patients Human to human transmission only from pregnant women to fetuses Treatment Penicillin and erythromycin Resistant to tetracycline & trimethoprim Prevention (Outbreaks) Difficult because the organism is ubiquitous At risk individuals should avoid undercooked vegetables, unpasteurized milk, undercooked meat, and all soft cheeses Listeria monocytogenes

Description gram-positive, non-endospore forming pleomorphic bacillus Colonize skin, respiratory, gastrointestinal, urinary & genital tracts Corynebacterium diptheriae Figure Pathogenicity (virulence factors) diphtheria toxin – only lysogenic phage infected bacteria; strains without phage are avirulent

Diseases Severe respiratory infections of nonimmune patients produce the signs and symptoms of diphtheria Pseudomembrane results from fluid that has thickened and adheres throughout the respiratory tract Corynebacterium diptheriae

Transmission Humans are only known hosts Very contagious- via respiratory droplets or skin contact Endemic in poor parts of the world that lack adequate immunization Treatment antitoxin to neutralize toxin before it binds to cells Penicillin and erythromycin kills the bacteria Prevention Immunization with the DTaP vaccine Corynebacterium diptheriae

Copyright © 2007 Pearson Education, Inc. publishing as Benjamin Cummings Mycobacterium tuberculosis Description –Acid-fast rod –Occurs in clumps –Very slow to grow –Aerobic –Thick waxy outer wall Pathogenicity –Resistant to drying –Survives phagocytosis Transmission from human to human

Copyright © 2007 Pearson Education, Inc. publishing as Benjamin Cummings Tuberculosis (TB)  Primary TB (Latent)  Results from the initial infection with M.tuberculosis  Secondary TB (Active)  Reestablishment of an active infection after a period of dormancy  Can spread throughout the body

Copyright © 2007 Pearson Education, Inc. publishing as Benjamin Cummings Primary Tuberculosis (Latent) Figure 19.22a

Copyright © 2007 Pearson Education, Inc. publishing as Benjamin Cummings Secondary Tuberculosis (Active) Figure 19.22b

Screening for Tuberculosis Tuberculin skin test –(+) = current or previous infection –Followed by X-ray or CT, acid-fast staining of sputum, culturing bacteria Acid-fast staining –All Mycobacterium species are positive

Copyright © 2007 Pearson Education, Inc. publishing as Benjamin Cummings Diagnosis, Treatment, and Prevention  Diagnosis  Tuberculin skin test identifies individuals with previous exposure to M. tuberculosis by the presence of a hard, red swelling at the test site  Chest x-rays are used to identify individuals with active disease  Treatment  Treatment with common antimicrobials is difficult because the bacteria grow slowly and can live within macrophages  Combination therapy must be used for a number of months to treat the disease

Copyright © 2007 Pearson Education, Inc. publishing as Benjamin Cummings Diagnosis, Treatment, and Prevention  Treatment  Primary line: Isoniazid and rifampin  Prevention  Prophylactic use of antibacterial drugs (Isoniazid) is used to treat patients who have shown a conversion from a negative to a positive skin test or were exposed to active cases of tuberculosis  Immunization with BCG vaccine is used in countries where TB is common

Copyright © 2007 Pearson Education, Inc. publishing as Benjamin Cummings Leprosy  Caused by Mycobacterium leprae  Bacteria have never been grown in cell-free culture  Cases of leprosy are becoming relatively rare  Transmission is via person-to-person contact or through a break in the skin

Copyright © 2007 Pearson Education, Inc. publishing as Benjamin Cummings Diagnosis, Treatment, and Prevention  Diagnosis  Based on the signs and symptoms of the disease  Loss of sensation in skin lesions in the case of tuberculoid leprosy  Disfigurement in the case of lepromatous leprosy  Treatment  Treatment with a combination of antimicrobial drugs  Lifelong treatment is sometimes needed  Prevention  Primarily prevented by limiting exposure to the pathogen  BCG vaccine provides some protection

Copyright © 2007 Pearson Education, Inc. publishing as Benjamin Cummings Other Mycobacterial Infections in AIDS Patients  Mycobacterium avium-intracellulare mycobacterial infection seen in AIDS patients and other immunocompromised patients  Infections are a result of ingestion of contaminated food or water  Infections can simultaneously affect almost every organ and result in massive organ failure  Treatment is difficult due to the disseminated nature of the infection