C H A P T E R © 2014 Pearson Education, Inc. PowerPoint ® Lecture Presentations prepared by Mindy Miller-Kittrell, North Carolina State University 20 Pathogenic Gram-Negative Cocci and Bacilli

© 2014 Pearson Education, Inc. Gram-Negative Bacteria Largest group of human bacterial pathogens Due in part to the presence of lipid A Triggers fever, vasodilation, inflammation and shock

© 2014 Pearson Education, Inc. Neisseria Gram-negative diplococci Oxidase positive Fimbriae, capsule and lipid A Two species are pathogenic to humans N. meningitidis meningococcus” N. gonorrhoeae “gonococcus”

© 2014 Pearson Education, Inc. Nasty, nasty, nasty Transient colonizer Attachment by surface fimbriae specific receptors on the oropharyngeal mucosa Spread via close contact secretions Lab workers at increased risk

© 2014 Pearson Education, Inc. Neisseria meningitidis

© 2014 Pearson Education, Inc. Neisseria meningitidis Route of transmission: Humans are the only natural carrier of Neisseria. meningitidis 10% of people are carriers- normal flora of upper respiratory tract Respiratory droplets transmit the bacteria among people living in close contact, especially students living in dormitories or military barracks

© 2014 Pearson Education, Inc. Neisseria meningitidis Disease: Most common cause of meningitis in young adults Symptoms: Starts out with flu-like symptoms sudden onset of fever, headache, and stiff neck. will often also cause nausea, vomiting, increased sensitivity to light, rash, and confusion. Causes life-threatening disease when the bacteria invade the blood or cerebrospinal fluid

© 2014 Pearson Education, Inc. Inflammation of the meninges (outer membrane covering of brain and spinal cord) Encephalitis- inflammation of the brain itself

© 2014 Pearson Education, Inc. Neisseria meningitidis Symptoms: Meningococcal meningitis and septicemia can result in death as early as 6 hours after initial symptoms Can produce blood coagulation and the formation of minute hemorrhagic lesions “petechiae”

© 2014 Pearson Education, Inc. Waterhouse-Friedricksen Syndrome

© 2014 Pearson Education, Inc. Neisseria meningitidis Treatment Immediate administration of penicillin Prevention Vaccine Meningococcal polysaccharide vaccine (MPSV4) Meningococcal conjugate vaccine (MCV4) since 2005 MCV4 is the preferred vaccine for people ages 11 through 55, but MPSV4 can be used when MCV4 is not available. derail-dreams-early-athletes-warn/

© 2014 Pearson Education, Inc. Neisseria gonorrhoeae Disease: Causes gonorrhea (the “Clap”) Only occurs in humans Virulence factors Fimbriae adhere to mucous membranes remove= nonpathogenic Survive inside neutrophils Produce enzyme to destroy IgA

© 2014 Pearson Education, Inc. Neisseria gonorrhoeae Symptoms: In men Painful urination and pus-filled discharge In women Often asymptomatic Can trigger Pelvic Inflammatory Disease - PID In newborns- Occurs during childbirth producing inflammation of the cornea ( Ophthalmia neonatorum)

© 2014 Pearson Education, Inc. Neisseria gonorrhoeae Diagnosis Presence of Gram-negative intracellular diplococci in pus from an inflamed penis Treatment Complicated due to resistant gonococcal strains Broad-spectrum intramuscular cephalosporins Prevention Most effective prevention is sexual abstinence Antibiotics in newborn’s eyes

© 2014 Pearson Education, Inc. Enterobacteriaceae Enteric bacteria -most common Gram-negative pathogens of humans Normal flora in intestines of most animals and humans Ubiquitous in water, soil, and decaying vegetation Virulence factors Outer membrane- Lipid A; O polysaccharides Capsules –K antigens ; Vi antigen Flagella -H antigens Fimbriae

© 2014 Pearson Education, Inc. Antigens and Virulence Factors Figure 20.8

© 2014 Pearson Education, Inc. Virulence Factors: Enteric Pathogens PLAY Virulence Factors: Enteric Pathogens

© 2014 Pearson Education, Inc. Escherichia coli Normal in the intestines of people and animals. Most E. coli are harmless and actually are an important part of a healthy human intestinal tract. Diseases: Most common cause of non- nosocomial UTI Gastroenteritis – caused by pathogenic E. coli strains

© 2014 Pearson Education, Inc. Escherichia coli O157:H7 Virulence factors Produces Shiga-like toxin (STEC) Infectious dose – less than 100 organisms Mode of transmission Usually food-borne or person-to-person Most commonly beef, leafy vegetables, dairy, fruits and nuts; In 50% of cattle feces; petting zoos Most epidemics associated with undercooked ground beef or unpasteurized milk or juice

© 2014 Pearson Education, Inc. E. coli O157:H7 Symptoms Causes bloody diarrhea, hemorrhagic colitis Onset of diarrhea usually takes place 3 to 4 days after exposure. About 8% of those with an O157 infection will develop Hemolytic Uremic Syndrome (HUS), a life threatening condition marked by hemolytic anemia and renal failure. Children from one to five years old are the most likely age group to develop HUS from a shiga toxin infection.

© 2014 Pearson Education, Inc. E. coli O157:H7 Treatment Diarrhea – fluid and electrolyte replacement- reduces the chance of HUS Antibiotics -Not recommended for diarrhea because self-limiting and release of Lipid A can worsen prognosis Antidiarrheals (like Immodium) can also increase the chance of HUS.

© 2014 Pearson Education, Inc. E. coli O157:H7 Prevention Good personal hygiene and proper sewage control are important in limiting the risk of infection E. coli O157:H7- cook meat thoroughly

© 2014 Pearson Education, Inc. Truly Pathogenic Enterobacteriaceae Include Salmonella, Shigella, Yersinia Almost always pathogenic due to numerous virulence factors: Produce type III secretion systems Introduce proteins into host cells Inhibit phagocytosis Rearrange the cytoskeletons of eukaryotic cells Induce apoptosis

© 2014 Pearson Education, Inc. Salmonella serotype enteritidis Found in the intestines and feces of most birds, reptiles, and man Salmonellosis occurs in most regions in the country Transmission Consumption of food contaminated with animal feces – commonly pet reptiles Poultry and eggs are also common sources cle_em.htm

© 2014 Pearson Education, Inc. Salmonella serotype enteritidis Salmonellosis Symptoms Fever, abdominal cramps, and diarrhea beginning 12 to 72 hours after consuming contaminated food/drink Can disseminate through bloodstream (especially in elderly, infants, those with impaired immune systems Treatment - Fluid and electrolyte replacement Prevention- Cooking food thoroughly; Hand hygiene

© 2014 Pearson Education, Inc. Salmonella typhi Typhoid fever Humans are the only host 1-3% recovered patients become carriers bacteria in gall bladder are shed in feces Transmission ingestion of food or water contaminated with sewage containing bacteria from carriers

© 2014 Pearson Education, Inc. Salmonella typhi Signs and symptoms of typhoid fever Usually have a sustained fever as high as 104°F Weakness, stomach pains, headache, or loss of appetite. In some cases, patients have a rash of flat, rose-colored spots. As many as 20% may die from complications of the infection. /

© 2014 Pearson Education, Inc. Figure Salmonella typhi Treatment replacement of fluids and electrolytes Antibiotics Remove gall bladder of carriers Prevention Handwashing Vaccines are available to individuals traveling to areas where typhoid fever is endemic (immunity lasts 1-2 yrs)

© 2014 Pearson Education, Inc. Shigella Disease Bacillary dysentery (shigellosis) Virulence factors diarrhea-inducing enterotoxin Type III Secretion System- causes macrophage death Shiga-toxin– stops protein synthesis in host cells

© 2014 Pearson Education, Inc. Shigella Transmission Ingestion of bacteria from contaminated hands or food Person to person particularly among children Symptoms Abdominal cramps, fever, diarrhea and purulent bloody stools starting 1-2 days after infected Shigellosis usually resolves in 5 to 7 days Figure 20.15

© 2014 Pearson Education, Inc. Shigella Complications Persons with diarrhea usually recover completely although it may be several months before their bowel habits are entirely normal. People who are genetically predisposed can develop post-infectious arthritis after S. flexneri infections Joint pain, irritation of the eyes, and painful urination Can last for months or years, and can lead to chronic arthritis.

© 2014 Pearson Education, Inc. Shigella Treatment Replacement of fluids and electrolytes Anti-diarrheal agents can make illness worse Antibiotics can reduce spread and shorten the duration of illness Prevention Good hand hygiene; improve sewage treatment No vaccine available

© 2014 Pearson Education, Inc. Yersinia enterocolitica Transmission Acquired via consumption of food or water contaminated with animal feces Disease Causes inflammation of the intestinal tract

© 2014 Pearson Education, Inc. Yersinia pestis Highly virulent, nonenteric pathogen Causes bubonic and pneumonic plague Virulence Factors: Virulence plasmids Adhesins Type III secretion systems (Killer Outbreaks)

© 2014 Pearson Education, Inc. Yersinia pestis Life Cycle Figure 20.16

© 2014 Pearson Education, Inc. Plague Y.pestis (Killed 25 million in 14 th century Europe) Bubonic plague – characterized by high fever and swollen, painful lymph nodes called buboes Pneumonic plague – rapidly developing lung infection

© 2014 Pearson Education, Inc. Bubonic Plague Symptoms High fever, swollen painful lymph nodes called buboes Bacteriemia can lead to DIC, subcutaneous hemorrhaging and death of tissue 50% mortality rate; 5% die even with treatment Death can occur within one week of onset of symptoms

© 2014 Pearson Education, Inc. Pneumonic Plague Transmission Spread of disease from bloodstream to lungs Person to person from airborne aerosols and sputum High mortality rate if untreated Treatment of Plague Sensitive to many antibiotics such as tetracycline, streptomycin and chloramphenicol Prevention of Plague Rodent control

© 2014 Pearson Education, Inc. Enterobacteriaceae: Sites of Infection Figure 20.18