Gram (-) Bacteria: Neisseria, Enterobacteriaceae, etc. Nestor T. Hilvano, M.D., M.P.H.

Learning Objectives 1.List features of Neisseria that contribute to its pathogenicity. 2.Compare and contrast the symptoms of gonorrhea in men and women. 3.Discuss the epidemiology of meningococcal diseases. 4.Describe diagnostic methods, treatment, and prevention of diseases of enteric bacteria. 5.Describe the pathogenesis and diseases of Escherichia coli O157:H7. 6.Differentiate between coliform and non-coliform opportunists. 7.Describe the diseases caused by non-coliform opportunistic enteric bacteria. 8.Describe the diseases caused by truly pathogenic enteric bacteria. 9.Contrast salmonellosis and shigellosis. 10.Identify and describe three diseases caused by species of Haemophilus. 11.Identify the three disease phases of pertussis. 12.Describe Pseudomonas aeruginosa as an opportunistic pathogen of burn victims and cystic fibrosis patients. 13. Describe the modes of transmission of tularemia. 14.Describe symptoms and treatment of Legionnaires disease. 15.Describe the mode of transmission of Q fever.

Neisseria gonorrhoeae Isolated in 1879 by Albert Neisser Gram (-), diplococci; aerobic; oxidase positive Fimbriae; antiphagocytic capsule; CW antigen lipo-oligosaccharide, composed of lipid A of lipopolysaccharide (endotoxin) Pathogenicity – transmitted by sex; adhere to mucous membranes, multiply, invade deeper tissue, and spread (PID) Increased vaginal (greenish-yellow or whitish) discharge, painful urination – in women Dx – organisms isolated; pus Rx – cephalosporins or quinolones

Neisseria meningitidis Gram (-), diplococci Antiphagocytic capsule Endotoxin – damages endothelial cells, petechial hemorrhages Tumbler test for petechial hemorrhages = pressed firmly against a septicemic rash, the marks will not fade Role in bacterial meningitis

Neisseria meningitidis Pathogenesis - spread via respiratory droplets/body fluids (kissing, sneezing, coughing); present in 4 to 5% (up to 40%) in closed quarters; low immunity for children < 10 y/o most common cause of meningitis in children and adults under 20 of age. Stages: a) 1 st stage – mild nasopharyngitis b) 2 nd stage – via lymph to blood →bacteremia = meningococcemia; fever, malaise, petechial hemorrhages (spotted fever) c) 3 rd stage – meningitis (1 to 30/10,000), fatal in 6 to 8 hrs., mortality of 35 to 80%, s/sx include headache, stiff neck, vomiting, confusion, delirium Dx – spinal tap, blood sample, skin lesions, nasopharynx; antibody test Rx – IV penicillin for patient; prophylaxis for close contacts

Gram (-), Facultative Anaerobic Bacilli 1. Enterobacteriaceae Enteric bacteria; intestinal microbiota Soil, water, and decaying vegetations Ferment glucose anaerobically; reduce nitrate to nitrite Lipopolysaccharide – virulence Pathogenic enteric bacteria include 1. coliform opportunists – E. coli; K. pneumonia; Serratia; Enterobacter, Hafnia, and Citrobacter are nosocomial opportunists 2. non-coliform opportunists – Proteus; Morganella; Providencia; Edwardsiella 3. true pathogens – Salmonella; Shigella; Yersinia 2. Pasteurellaceae Oxidase (+), small,nonmotile, requires heme or cytochromes Pasteurella multicida; Haemophilus influenza

Escherichia coli Most common coliform; food – water borne diseases Fimbriae for attachment Strains - enterotoxigenic = enterotoxin + endotoxin → traveller’s diarrhea - enteroinvasive = invasion of intestinal wall → inflammation, fever, diarrhea, dysentery - enterohemorrhagic = E. coli 0157:H7; epidemic seen with undercooked meat or unpasteurized milk/juice * O polysaccharide 157 * flagellar H7 antigen * bloody diarrhea; hemorrhagic colitis * hemolytic uremia syndrome McConkey agar: -Selective for gm. – -E. coli and differentiates lactose Fermenting E. coli (red to pink colonies)

Klebsiella pneumonia Digestive and respiratory system Capsule = mucoid appearance and protects from phagocytosis Pneumonia - bloody sputum; alcoholics and immunocompromised at higher risk Bacteremia, meningitis, wound infection, and UTI

Salmonella Gm (-); peritrichous bacilli Lives in intestines and eliminated in feces Enteric fever a) Typhoid fever – S. typhi; Rx- antibiotics (ampicillin) b) Paratyphoid fever – S. paratyphi; milder disease * Pathogenesis – fecal-oral route from contaminated water, food, drink, and carrier; into lymphatics, RES (liver, spleen, BM); bloodstream * Endotoxemia → fever, headache, weakness, diarrhea and rose spots on abdomen Gastroenteritis and dysentery - Salmonellosis – S. typhimurium; S. enteritidis - generally no bacteremia or septicimia; not invasive - Pathogenesis – from meat, milk, eggs, chicken, fish - GI infection after 12 – 48 hrs. with nausea, vomiting, abdominal pain, diarrhea (non-bloody), prostration, fever - Rx: fluid and electrolyte replacement

Shigella Gm (-), no flagella, multiply intracellularly More prevalent in trophics and subtrophics Shigellosis – S. sonnei in U.S.; char. by abdominal cramps, fever, diarrhea, and purulent bloody stools (severe form of dysentery) Pathogenesis – fecal-oral route; enter the intestinal epith. cells and multiply; causes abscess and inflammation of intestinal mucosa; cause dysentery (loss of fluids/electrolytes) Mortality 20%

Yersinia pestis virulent, nonenteric pathogen; causes 1. bubonic plague - bite from infected flea - high fever; swollen, painful lymph nodes (buboes) within a week - untreated cases lead to bacteremia and gangrene, 50% fatal 2. pneumonic plague - spread from bloodstream into lungs; between human via airborne - respiratory distress within 24 hrs.; fatal

Haemophilus influenza Gm (-), coccobacillus; oxidase (+) Require blood agar Found in respiratory flora; transmitted by droplets (infants & children) Polysaccharide capsule - resist phagocytosis H. influenza b – most common cause of infantile meningitis (before immunization; prevented by Hib vaccine) Also causes otitis media, conjunctivitis, sinusitis, epiglotitis, arthritis, and inflammation of skin Rx. – antibiotics (cephalosporins) Prev – Hib immunization at 2, 4, 6, 12 months H. ducreyi - causes chancroid (soft chancre, painful genital ulcer) ; a major co-factor in transmission of HIV H. aphrophilus (endocarditis)

Bordetella pertussis Obligate aerobe; gm (-), coccobacilli Capsule – virulence Exotoxin – pertussis toxin, inhibits ciliary activity Endotoxin – cytotoxin, kills epithelium Pathogenesis –inhalation of organism, binding to ciliated epithelium (non-invasive), inhibition of ciliary movement, inflammation and necrosis of tracheal epithelium, irritation and cough Whooping cough – one of most frequent/severe disease of infants in U.S. until immunization in 1940s

Bordetella pertussis 3 stages 1˚ stage – catarrhal ; 7-16 days; mild cough to bad cough (sneezing, malaise, fever) 2˚ stage – paroxysmal; 2-6 weeks; severe cough with whoop, vomiting, exhaustion, and cyanosis 3˚ stage – convalescence; 3-4 weeks; possible secondary complication of staph/ streph Dx a. cough on Bordet-Genou agar plate, incubate and identify organism b. nasopharyngeal swab, grow on medium cont’g penicillin Rx – antibiotics Prev – immunity after convalescence; DPT vaccine

Pseudomonas aeruginosa Gm (-), aerobic bacilli Soil, decaying organic matter, moist environment (pools,sponges, contact lens solution) Fimbriae and capsule – attachment and resist phagocytosis Endotoxin (lipid A) in cell wall Exotoxin A and exoenzymes S – inhibit protein synthesis and contribute to cell death in eukaryotic cells Nosocomial infections, common in burn wounds, in lungs of cystic fibrosis; but can colonize organs and systems Pyocyanin discoloration of tissues – indicates massive infection Resistant to wide range of antibiotics

Legionella pneumophila Legionellosis (legionnaire’s disease) Discovered in 1976 (meeting of Am. Legion in Philadelphia) Aerobic, gm (-) bacilli From natural waters Resistant to chlorine Intracellular in amoeba (warm waters, showers, pools) Fever, chills, dry nonproductive cough, headache, and pneumonia Dx – fluorescent antibody or other serologic tests Rx – erythromycin

Other Gm (-) Aerobic Bacilli 1.Bartonella – found in animals but known to cause human diseases; bartonellosis; trench fever; cat-scratch disease (localized swelling and tender L.N. in children) 2. Brucella – from unpasteurized contaminated milk or contaminated animal blood, urine or placentas; brucellosis (big bang disease and undulant fever), spread to organs, abortions, granuloma formation, joint pain 3. Francisella – cause zoonotic disease called tularemia (rabbit fever or tick fever); via biting arthropod or through unbroken skin 4. Coxiella – C. burnetii, via aerosolized dried feces and urine of mammals and birds, cause Q fever (fever,headache, myalgia, and mild pneumonia)

Endotoxin Produced by gram – bacteria Integral part of the cell wall Lipid A of lipopolysaccharide Heat stable Diverse range of host cells and systems affected Diverse range of effects Toxoids cannot be made

Homework 1.Identify causative agent of items listed: petechial hemorrhage in tumbler test and most common cause of meningitis under 20 of age; pus urethral discharge in STD; traveler’s diarrhea; pneumonia in immunocompromised patient; typhoid fever; shigellosis; buboes; Q fever; tularemia; most common cause of infantile meningitis; chancroid; legionnaire’s disease; most common cause of nosocomial infection and in burn infection. 2.Describe the 3 strains of E. coli as to its toxins. 3.List microorganisms that cause gastroenteritis (diarrhea and dysentery) in human. 4.Discuss the clinical stages of pertussis. 5.Give the characteristics of endotoxin.