Gram Negative Pathogens

Question 1

Neisseria

Answer 1

Diplococcus

Characteristics-Aerobic, catalase and oxidase positive, pyogenic and sensitive to environment, grown on chocolate agar and high CO2

Virulence Factors-Gonorrhea-attachment pili, transmission by sexual contact. Meningitis- humans are only natural carrier, normal flora of resp. tract.,transmitted in respiratory droplets, Capsule and endotoxin, 13 serotypes

Diseases-Two Diseases: Gonorrhea-most common reportable disease in U.S., men-anterior urethra with pus and painful urination, women-vaginal-cervical junction, asymptomatic, passed to infant, salpingitis, PID; Meningococcal meningitis-harmful if in blood or CSF, lethal within 6 hours, sensitive to light, stiff neck, fever, headache

Treatment-Gonorrhea-Penicillin, but 50% are resistant. Current is Cephalosporin with tetracycline; Meningitis: i.v. Penicillin or cephalosporins, but EARLY, Quadrivalent Vaccine

Question 2

E. Coli

Answer 2

Bacillus

Characteristics-Facultative Aerobes, Catalase positive, oxidase negative. Normal flora in humans, 3 types of antigens-O, K, and H

Virulence Factors-Killed by disinfectants but not AB’s, major NOSOCOMIAL infection, 1/4 of bacterial population. Coliforms in water=not properly treated. Attachment pili and exotoxins

Diseases-UTI(major non-nosocomial) and gastroenteritis, Uropathic (UPEC)-UTI potential; Enterotoxigenic (ETEC)-traveler’s and infant diarrhea (like cholera); Enteropathogenic (EPEC)-bottle-fed infant diarrheas; Enterohemorrhagic (EHEC)-hemolytic uremic syndrome d2 toxin-0157:H7; Enteroinvasive (EIEC)-dysentery on humans only

Treatment-

Question 3

Shigella

Answer 3

Characteristics-non-motile

transmission from small flies, fingers, fomites, food, and feces

Virulence Factors- Parasite in digestive tract of humans, diarrhea inducing endotoxin, which causes apoptosis

Diseases-SHIGELLOSIS

Treatment-

Question 4

Salmonella

Answer 4

Bacillus

Transmission-feces of birds, reptiles and mammals

Virulence Factors-

Diseases-S. enterica serovar Typhimurium-Salmonellosis; S. typhi-typhoid fever (humans only) via intestion of food or water. From intestines go to liver, spleen, bone marrow, and gall bladder. TYPHOID MARY, produce ruffles in M cells

Treatment-Antimicrobial drugs or Vaccines

Question 5

B. pertussis

Answer 5

Coccobacillus

Characteristics-non-motile and aerobic

Virulence Factors-Adhesins and toxins, inhaled in aerosols and multiply in epithelial cells

Diseases- pertuss-WHOOPING COUGH

Treatment-

Question 6

Y.pestis

Answer 6

Characteristics-Normal pathogens in animals, tranferred from flea to animal, various virulence factors expressed in flea vs. mammals

Virulence Factors-

Diseases-BUBONIC PLAGUE-high fever and swollen, painful lymph nodes called buboes; Pneumonic plague-infection of lungs

Treatment-

Question 7

Pseudomonas aeruginosa

Answer 7

Bacillus

Characteristics-Aerobic, associated with plants and water, problems in hospitals because they are so ubiquitous, opportunistic, not part of normal flora

Virulence Factors-Form biofilm to prevent phagocytosis, produce blue pigment

Diseases-Infects lungs of cystic fibrosis patients by forming biofilm, common in burn wards, HOTTUBITIS

Treatment-Difficult due to resistant strains

Question 8

Francisca tularensis

Answer 8

Coccobacillus

transmission,

Question 9

Legionella pneumophila

Answer 9

Pleomorphic

Characteristics-Aerobic

Virulence Factors-16 serotypes; 1-4 cause disease, enter by coiling phagocytosis, multiply inside macrophage, prevent phagosome/lysosome fusion and recruit secretory vesicles from ER.

Diseases-Legionnaires’ disease-contracted by inhaling aerosols from water source; more often in immunocompromised individuals, resulting in pneumonia

Treatment-

Question 10

Rickettsias

Answer 10

Small, very thin cell wall

Characteristics-Obligate INTRACELLULAR parasites

Virulence Factors-

Diseases- Mountain spotted fever- Rickettsia rickettsii-trasmitted by wood ticks; Epidemic Typhus-prowazekii-transmitted by body lice-high mortality

Treatment-

Question 11

Clamydias

Answer 11

No cell wall, but outer membrane

Characteristics-Obligate intracellular parasites, two developmental cycle forms: elementary and reticulate

Virulence Factors-
STD and Trachoma (mostly in children), Lymphogranuloma veneruem-transient genital lesions and swollen, painfully inflamed, inguinal lymph nodes; Trachoma-disease of eye, growth occurs in conjunctiva, scars abrade the eye and lead to blindness.
Diseases-

Treatment-

Question 12

Spirochetes-Trepanoma

Answer 12

Helical,8-20 coils

Characteristics-

Virulence Factors-Corkscrew causes penetration, obligate parasite in humans, transmission via sexual contact or spread to fetus (death or retardation)

Disease-SYPHILIS-Chancre, then rash and condyloma (grey, flat wart-like), then Gummas and Neurologic symptoms

Treatment-

Question 13

Spirochetes-borrelia

Answer 13

Tight Coils

Characteristics-

Virulence Factors-Tick-Borne

Disease-LYME DISEASE, RELAPSING FEVER

Treatment-Penicillin or or Tetracycline effective in first stage

Question 14

V.cholerae

Answer 14

Characteristics-

Virulence Factors-Cholera Toxin

Disease-Cholera fire-hose diarrhea,-cAMP, loss of ions and water

Treatment-Fluid and electrolyte replacement

Question 15

Spirochetes Leptospira

Answer 15

Loose Coils

Characteristics-motile, aerobes

Virulence Factors-most widespread zoonotic disease

Disease-Leptosporosis- contact with urine from animals or contaminated bodies of water

Treatment-

Question 16

Campylobacter

Answer 16

MOST COMMON cause of BACTERIAL GASTROENTERITIS in U.S. due to contaminated food, milk or water. Often from Chickens

Question 17

H. Pylori

Answer 17

Slightly helical

Characteristics-motile

Virulence Factors-Can live in stomach because of urease, which produces ammonina and bicarbonate, produce toxins

Disease-Gastritis and duodenal ulcers

Treatment-