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 Constitute largest group of human bacterial pathogens Due in part to lipid A in the bacterial cell wall Fever, vasodilation, inflammation, shock Most Gram-negative bacteria that breach skin or mucous membranes, grow at 37  C, and evade the immune system can cause disease in humans

© 2014 Pearson Education, Inc. Pathogenic Gram-Negative Cocci: Neisseria Structure and Physiology of Neisseria Only genus of Gram-negative cocci that regularly causes disease in humans Aerobic, nonmotile, arranged as diplococci Oxidase positive Distinguishes from many other Gram-negative pathogens Pathogenic strains have a polysaccharide capsule, and a cell wall containing lipid A Two species pathogenic to humans N. gonorrhoeae N. meningitidis

© 2014 Pearson Education, Inc. Figure 20.1 Artist's rendition of diplococci of Neisseria gonorrhoeae.

© 2014 Pearson Education, Inc. Pathogenic Gram-Negative Cocci: Neisseria The Gonococcus: Neisseria gonorrhoeae Pathogenesis, epidemiology, and disease Causes gonorrhea Only occurs in humans Sexually transmitted disease Increased risk of infection with increasing sexual encounters Most cases in the United States occur in adolescents Cases have declined over the past decades More common in females than in males

© 2014 Pearson Education, Inc. Pathogenic Gram-Negative Cocci: Neisseria The Gonococcus: Neisseria gonorrhoeae Pathogenesis, epidemiology, and disease Gonococci adhere to the genital, urinary, and digestive tract Gonococci can evade the immune system Secrete protease that cleaves secretory IgA Survive within neutrophils

© 2014 Pearson Education, Inc. Pathogenic Gram-Negative Cocci: Neisseria The Gonococcus: Neisseria gonorrhoeae Pathogenesis, epidemiology, and disease Gonorrhea in men Inflammation causes painful urination and pus-filled discharge Gonorrhea in women Often asymptomatic Can trigger pelvic inflammatory disease Infections can occur outside the reproductive tract Cause proctitis, pharyngitis, and gingivitis Infection of the cornea or respiratory tract of newborns can occur during childbirth

© 2014 Pearson Education, Inc. Pathogenic Gram-Negative Cocci: Neisseria The Gonococcus: Neisseria gonorrhoeae Diagnosis, treatment, and prevention Diagnosis Asymptomatic cases identified with genetic probes Gram-negative diplococci in pus from inflamed penis Treatment Complicated due to resistant strains Broad-spectrum intramuscular cephalosporins Prevention Sexual abstinence, monogamy, and proper condom use Eye infections in newborns prevented with antimicrobials

© 2014 Pearson Education, Inc. Pathogenic Gram-Negative Cocci: Neisseria The Meningococcus: Neisseria meningitidis Pathogenicity, epidemiology, and disease Most common cause of meningitis in individuals under 20 Can be normal microbiota of the upper respiratory tract Bacteria transmitted by respiratory droplets among people living in close contact Meningitis can cause death within 6 hours of symptoms Meningococcal septicemia can also be life threatening

© 2014 Pearson Education, Inc. Figure 20.3 Petechiae in meningococcal septicemia.

© 2014 Pearson Education, Inc. Pathogenic Gram-Negative Cocci: Neisseria The Meningococcus: Neisseria meningitidis Diagnosis, treatment, and prevention Diagnosis Rapid diagnosis critical Gram-negative diplococci in phagocytes of the CNS Treatment Immediate administration of intravenous penicillin Prevention Asymptomatic carriers make eradication unlikely Vaccine against some meningococcal strains is available

© 2014 Pearson Education, Inc. Pathogenic, Gram-Negative, Facultatively Anaerobic Bacilli Two families contain most human pathogens Enterobacteriaceae Pasteurellaceae Oxidase test distinguishes between these families Includes important nosocomial pathogens

© 2014 Pearson Education, Inc. Gram-positive bacteria Gram-negative bacteria Yeast Enterobacteriaceae: coliforms Enterobacteriaceae: noncoliforms Escherichia Klebsiella Serratia Enterobacter Citrobacter Proteus Salmonella Pseudomonas (not in family Enterobacteriaceae) Figure 20.5 Relative causes of nosocomial infections in the United States.

© 2014 Pearson Education, Inc. Pathogenic, Gram-Negative, Facultatively Anaerobic Bacilli The Enterobacteriaceae: An Overview Intestinal microbiota of most animals and humans Ubiquitous in water, soil, and decaying vegetation Enteric bacteria are the most common Gram-negative pathogens of humans

© 2014 Pearson Education, Inc. Pathogenic, Gram-Negative, Facultatively Anaerobic Bacilli The Enterobacteriaceae: An Overview Structure and physiology of the Enterobacteriaceae Motile bacilli and coccobacilli All reduce nitrate to nitrite and ferment glucose Grow best in aerobic environments Species distinguished based on biochemical properties, motility, and colony characteristics

© 2014 Pearson Education, Inc. Pathogenic, Gram-Negative, Facultatively Anaerobic Bacilli The Enterobacteriaceae: An Overview Diagnosis Enteric bacteria in urine, blood, cerebrospinal fluid Biochemical tests rapidly identify enteric bacteria Treatment Diarrhea is typically self-limited Internal infections treated with antimicrobials Prevention Good personal hygiene and proper sewage control

© 2014 Pearson Education, Inc. Pathogenic, Gram-Negative, Facultatively Anaerobic Bacilli The Enterobacteriaceae: An Overview Pathogenic Enterobacteriaceae classified into three groups Coliforms Rapidly ferment lactose Normal microbiota but may be opportunistic pathogens Noncoliform opportunists Do not ferment lactose True pathogens

© 2014 Pearson Education, Inc. Pathogenic, Gram-Negative, Facultatively Anaerobic Bacilli Coliform Opportunistic Enterobacteriaceae Coliforms Aerobic or facultatively anaerobic, Gram-negative, rod-shaped bacteria that ferment lactose to form gas in lactose broth Commonly found in soil, on plants, and on decaying vegetation Colonize the intestinal tracts of animals and humans Coliforms in water indicate impure water and poor sewage treatment

© 2014 Pearson Education, Inc. Pathogenic, Gram-Negative, Facultatively Anaerobic Bacilli Coliform Opportunistic Enterobacteriaceae Escherichia coli Most common and important of the coliforms E. coli antigens used to identify particular strains Virulent strains have virulence plasmids Have genes for fimbriae, adhesins, exotoxins Causes several diseases Gastroenteritis is most common disease Produces diarrhea, cramps, nausea, and vomiting Often mediated by enterotoxins Major cause of pediatric diarrhea in developing countries

© 2014 Pearson Education, Inc. Pathogenic, Gram-Negative, Facultatively Anaerobic Bacilli Coliform Opportunistic Enterobacteriaceae Escherichia coli Common cause of non-nosocomial urinary tract infections Occur more often in women than men E. coli O157:H7 Most prevalent pathogenic E. coli in developed countries Causes diarrhea, hemorrhagic colitis, hemolytic uremic syndrome Associated with consumption of undercooked ground beef or contaminated milk or fruit juice Produces type III secretion system and Shiga-like toxin

© 2014 Pearson Education, Inc. Pathogenic, Gram-Negative, Facultatively Anaerobic Bacilli Coliform Opportunistic Enterobacteriaceae Klebsiella In digestive and respiratory systems of humans and animals Capsule protects the bacteria from phagocytosis Can cause opportunistic infections K. pneumoniae Most commonly isolated pathogenic species Causes pneumonia May be involved in bacteremia, meningitis, wound infections.

© 2014 Pearson Education, Inc. Capsules Figure The prominent capsule of Klebsiella pneumoniae.

© 2014 Pearson Education, Inc. Pathogenic, Gram-Negative, Facultatively Anaerobic Bacilli Coliform Opportunistic Enterobacteriaceae Serratia Produce a red pigment when grown at room temperature Can grow on catheters, in saline solutions, and on other hospital supplies Can cause life-threatening opportunistic infections in immunocompromised patients Frequently resistant to antimicrobial drugs

© 2014 Pearson Education, Inc. Pathogenic, Gram-Negative, Facultatively Anaerobic Bacilli Coliform Opportunistic Enterobacteriaceae Enterobacter, Hafnia, and Citrobacter Found in soil, water, decaying vegetation, and sewage Reside in the digestive tracts of animals and humans Enterobacter can contaminate dairy products All can be opportunistic pathogens Cause nosocomial infections in immunocompromised patients Difficult to treat due to resistance to antimicrobial drugs

© 2014 Pearson Education, Inc. Pathogenic, Gram-Negative, Facultatively Anaerobic Bacilli Noncoliform Opportunistic Enterobacteriaceae Proteus Facultative anaerobe Proteus mirabilis Most commonly associated with human disease Associated with urinary tract infections in patients with long-term urinary catheters Infection-induced kidney stones can develop Resistant to many antimicrobial drugs

© 2014 Pearson Education, Inc. Figure The wavelike concentric rings of the swarming Proteus microbilis.

© 2014 Pearson Education, Inc. Pathogenic, Gram-Negative, Facultatively Anaerobic Bacilli Noncoliform Opportunistic Enterobacteriaceae Morganella, Providencia, and Edwardsiella Nosocomial infections in immunocompromised patients Primarily involved in urinary tract infections Providencia may cause kidney stones

© 2014 Pearson Education, Inc. Pathogenic, Gram-Negative, Facultatively Anaerobic Bacilli 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. Pathogenic, Gram-Negative, Facultatively Anaerobic Bacilli Truly Pathogenic Enterobacteriaceae Salmonella Motile, peritrichous bacilli Live in the intestines of birds, reptiles, and mammals Most human infections due to consuming food contaminated with animal feces Poultry and eggs are also common sources of Salmonella Can cause salmonellosis and typhoid fever

© 2014 Pearson Education, Inc. Pathogenic, Gram-Negative, Facultatively Anaerobic Bacilli Truly Pathogenic Enterobacteriaceae Salmonella Typhoid fever Caused by Salmonella enterica serotype Typhi Humans are the only host Carriers are often asymptomatic Bacteria ingested in contaminated food or water Bacteria pass through intestines into the bloodstream Phagocytic cells ingest the bacteria and carry them to various organs Causes gastroenteritis, bacteremia, and peritonitis

© 2014 Pearson Education, Inc. Figure The incidences of diseases caused by Salmonella in the United States.

© 2014 Pearson Education, Inc. Pathogenic, Gram-Negative, Facultatively Anaerobic Bacilli Truly Pathogenic Enterobacteriaceae Salmonella Salmonellosis treated with fluid and electrolyte replacement Typhoid fever treated with antimicrobial drugs Gallbladder may be removed from carriers to prevent infection of others Vaccines provide temporary protection to travelers

© 2014 Pearson Education, Inc. Pathogenic, Gram-Negative, Facultatively Anaerobic Bacilli Truly Pathogenic Enterobacteriaceae Shigella Oxidase-negative, nonmotile pathogens Primarily a parasite of the digestive tract of humans Produce diarrhea-inducing enterotoxin Four well-defined species S. dysenteriae S. flexneri S. boydii S. sonnei

© 2014 Pearson Education, Inc. Pathogenic, Gram-Negative, Facultatively Anaerobic Bacilli Truly Pathogenic Enterobacteriaceae Shigella Shigellosis Severe form of dysentery S. sonnei is predominant cause in industrialized nations S. flexneri predominates in developing countries Associated with poor hygiene and sewage treatment People ingest bacteria on their own contaminated hands or in contaminated food Person-to-person spread is possible

© 2014 Pearson Education, Inc. Pathogenic, Gram-Negative, Facultatively Anaerobic Bacilli Truly Pathogenic Enterobacteriaceae Yersinia Normal pathogen of animals Three important species All contain virulence plasmids Adhesins Allow attachment to human cells Type III secretion systems Injection of proteins that causes apotosis of macrophage and neutrophils

© 2014 Pearson Education, Inc. Pathogenic, Gram-Negative, Facultatively Anaerobic Bacilli Truly Pathogenic Enterobacteriaceae Yersinia Y. enterocolitica Acquired by consumption of contaminated food or water Causes inflammation of the intestinal tract Y. pseudotuberculosis Causes less severe inflammation of the intestines Y. pestis Highly virulent, nonenteric pathogen Causes bubonic and pneumonic plague

© 2014 Pearson Education, Inc. Figure The natural history and transmission of Yersinia pestis. Natural endemic reservoir hosts (rodents) Amplifying hosts (most mammals) Direct contact Flea bite Normal lymph nodes Bubo Bubonic plague Pneumonic plague Airborne transmission

© 2014 Pearson Education, Inc. Pathogenic, Gram-Negative, Facultatively Anaerobic Bacilli Truly Pathogenic Enterobacteriaceae Yersinia Y. pestis Diagnosis and treatment must be rapid Fast progression and deadliness of the plague Characteristic symptoms are usually diagnostic Many antibacterial drugs are effective

© 2014 Pearson Education, Inc. Figure Sites of infection by some common members of the Enterobacteriaceae.

© 2014 Pearson Education, Inc. Pathogenic, Gram-Negative, Facultatively Anaerobic Bacilli The Pasteurellaceae Most are small, nonmotile, facultative anaerobes Require heme or cytochromes for growth Two genera contain most human pathogens of this family Pasteurella Haemophilus

© 2014 Pearson Education, Inc. Pathogenic, Gram-Negative, Facultatively Anaerobic Bacilli The Pasteurellaceae Pasteurella Normal microbiota in oral and nasopharyngeal cavities of animals Humans infected via animal bites or inhalation of aerosols Most cases produce localized inflammation Widespread infection and bacteremia can occur in immunosuppressed individuals Diagnosis is by identification of bacteria in patient specimens Antibacterial drugs are effective treatment

© 2014 Pearson Education, Inc. Pathogenic, Gram-Negative, Facultatively Anaerobic Bacilli The Pasteurellaceae Haemophilus Small, pleomorphic bacilli Require heme and NAD + for growth Colonize mucous membranes of humans and some animals Some species cause opportunistic infections H. ducreyi causes sexually transmitted disease

© 2014 Pearson Education, Inc. Pathogenic, Gram-Negative, Facultatively Anaerobic Bacilli The Pasteurellaceae Haemophilus Haemophilus influenzae Most strains have capsule that resists phagocytosis H. influenzae type b is most significant strain Common cause of meningitis prior to vaccination Hib vaccine has eliminated most disease by H. influenzae in the United States Other H. influenzae strains cause a variety of diseases Conjunctivitis, sinusitis, dental abscesses, meningitis

© 2014 Pearson Education, Inc. Pathogenic, Gram-Negative, Aerobic Bacilli Bartonella Aerobic bacilli Found in animals but only causes disease in humans Three species are pathogenic Bartonella bacilliformis Bartonellosis Causes fever, anemia, headache, muscle and joint pain, and chronic skin infections Often fatal Transmitted by bloodsucking sand flies Endemic in Peru, Ecuador, and Columbia

© 2014 Pearson Education, Inc. Pathogenic, Gram-Negative, Aerobic Bacilli Bartonella Bartonella quintana Trench fever Common during World War I Transmitted by human body lice Causes headaches, fever, pain in the long bones Causes two diseases in immunocompromised patients Bacillary angiomatosis Bacillary peliosis hepatis

© 2014 Pearson Education, Inc. Pathogenic, Gram-Negative, Aerobic Bacilli Bartonella Bartonella henselae Cat-scratch disease Transmitted through cat scratches and bites Common disease in children in the United States Causes fever, malaise, and swelling at infection site Bartonella infections are treated with various antimicrobials

© 2014 Pearson Education, Inc. Figure Cat scratch disease.

© 2014 Pearson Education, Inc. Pathogenic, Gram-Negative, Aerobic Bacilli Brucella Small, nonmotile, aerobic coccobacilli Can infect animals or humans Brucella melitensis responsible for all disease in humans Causes brucellosis Often an asymptomatic or mild disease Illness is characterized by a fluctuating fever Human infection due to contact with contaminated dairy products or infected animal parts Characterized by fluctuating fever Vaccine available for use in domesticated animals

© 2014 Pearson Education, Inc. Pathogenic, Gram-Negative, Aerobic Bacilli Bordetella Pathogenesis, epidemiology, and disease Small, aerobic, nonmotile coccobacillus B. pertussis is the most important Causes pertussis (whooping cough) Most cases of disease are in children Adhesins and toxins mediate the disease Pertussis toxin Adenylate cyclase toxin Dermonecrotic toxin Tracheal cytotoxin Bacteria inhaled in aerosols multiply in epithelial cells

© 2014 Pearson Education, Inc. Pathogenic, Gram-Negative, Aerobic Bacilli Bordetella Diagnosis, treatment, and prevention Diagnosis Pertussis symptoms usually diagnostic Treatment Primarily supportive Prevention Immunization with DTaP or Tdap vaccine

© 2014 Pearson Education, Inc. Pathogenic, Gram-Negative, Aerobic Bacilli Burkholderia Burkholderia cepacia Aerobic, flagellated betaproteobacterium Can decompose a broad range of organic molecules Assists in cleanup of contaminated environmental sites Used by farmers to reduce fungal infection of plant crops Opportunistic pathogen of cystic fibrosis patients Resistant to many antimicrobial drugs Burkholderia pseudomallei Causes melioidosis

© 2014 Pearson Education, Inc. Pathogenic, Gram-Negative, Aerobic Bacilli Pseudomonads Aerobic bacilli Ubiquitous in soil, decaying organic matter, moist environments Problematic in hospitals Opportunistic pathogens

© 2014 Pearson Education, Inc. Pathogenic, Gram-Negative, Aerobic Bacilli Pseudomonads Pseudomonas aeruginosa Rarely part of normal human microbiota Rarely causes disease Despite producing various virulence factors Fimbriae, adhesins, capsule, toxins, and enzymes Opportunistic infections in immunocompromised patients Can colonize almost any organ or system Also infects the lungs of cystic fibrosis patients Biofilm protects bacteria from phagocytosis Treatment is difficult due to drug resistance

© 2014 Pearson Education, Inc. Figure A Pseudomonas aeruginosa infection.

© 2014 Pearson Education, Inc. Pathogenic, Gram-Negative, Aerobic Bacilli Pseudomonads Moraxella and Acinetobacter Aerobic, short, plump bacilli Rarely cause disease in humans Moraxella catarrhalis Opportunistic infections of the sinuses, bronchi, ears, and lungs Acinetobacter Grows in soil, water, and sewage Opportunistic infections of the respiratory, urinary, and central nervous systems

© 2014 Pearson Education, Inc. Pathogenic, Gram-Negative, Aerobic Bacilli Pseudomonads Francisella tularensis Nonmotile, strictly aerobic coccobacillus Intracellular parasite of animals and amoebae in water Diverse range of hosts Reservoirs in the United States include rabbits, muskrats, and ticks

© 2014 Pearson Education, Inc. Pathogenic, Gram-Negative, Aerobic Bacilli Pseudomonads Francisella tularensis Tularemia Zoonotic disease Spread through bite of an infected tick or contact with an infected animal Also spread by bacteria in meat, water, and in aerosols The bacteria is highly infectious Tularemia may be misdiagnosed Symptoms are similar to other diseases Treated with antimicrobial drugs Infection prevented by avoiding reservoirs of Francisella

© 2014 Pearson Education, Inc. Pathogenic, Gram-Negative, Aerobic Bacilli Pseudomonads Legionella Pathogenesis, epidemiology, and disease Aerobic, slender, pleomorphic bacteria Universal inhabitants of water Humans inhale bacteria in aerosols from water sources Intracellular parasites L. pneumophila causes most disease in humans

© 2014 Pearson Education, Inc. Pathogenic, Gram-Negative, Aerobic Bacilli Pseudomonads Legionella Pathogenesis, epidemiology, and disease Legionnaires' disease Results in pneumonia Can be fatal Particularly immunocompromised individuals Pontiac fever Similar to Legionnaires' disease Doesn't produce pneumonia and is not fatal

© 2014 Pearson Education, Inc. Pathogenic, Gram-Negative, Aerobic Bacilli Pseudomonads Legionella Diagnosis, treatment, and prevention Diagnosis Identification of Legionella by antibody staining or other serological tests Treatment Pontiac fever is self-limiting Fluoroquinolone and azithromycin used to treat Legionnaires' disease Prevention Elimination of the bacteria is not feasible

© 2014 Pearson Education, Inc. Pathogenic, Gram-Negative, Aerobic Bacilli Pseudomonads Coxiella Coxiella burnetii Extremely small, aerobic bacteria Obligate intracellular parasite Originally thought to be a virus Infective body enables survival in harsh environment Human disease associated with farm animals and pets Transmitted mainly by inhalation of the infective bodies

© 2014 Pearson Education, Inc. Pathogenic, Gram-Negative, Aerobic Bacilli Pseudomonads Coxiella Coxiella burnetii Q fever Causes fever, headache, chills, muscle pain, mild pneumonia Chronic Q fever can cause endocarditis years later Chronic Q fever treated with long-term antimicrobials Vaccine developed but not available in the United States Prevent by avoiding inhalation of contaminated dust

© 2014 Pearson Education, Inc. Pathogenic, Gram-Negative, Anaerobic Bacilli Predominant microbiota of the gastrointestinal, urinary, reproductive, and lower respiratory tracts Important for human health Inhibit the growth of most pathogens Synthesize vitamins and vitamin precursors Aid in digestion of food Cause disease when introduced into other parts of the body

© 2014 Pearson Education, Inc. Pathogenic, Gram-Negative, Anaerobic Bacilli Bacteroides Normal microbiota of the intestinal and upper respiratory tracts Bacteroides fragilis Most important pathogen of this genus Produces various virulence factors Involved in a variety of conditions Abdominal infections Genital infections in women Wound infections of the skin Infections can be treated with metronidazole

© 2014 Pearson Education, Inc. Pathogenic, Gram-Negative, Anaerobic Bacilli Prevotella Normal microbiota of urinary, genital, and upper respiratory tracts Differ from Bacteroides in their sensitivity to bile Produce several virulence factors Involved in various conditions Sinus and ear infections Almost all periodontal infections Gynecological infections Brain abscesses Abdominal infections Treat by surgical removal of infected tissue and carbapenem