Principles of Epidemiology and Microbiology
Lesson 2: Public Health Microbiology
Section II: Bacteria
2-10
2-10. PATHOGENIC BACTERIA
Table 2-2 presents a list of the principal pathogenic bacteria of public health importance, organized in such a way as to illustrate the means of identification
|
IDENTIFICATION GROUP |
SPECIES |
CAUSATIVE AGENT |
REMARKS |
|
GRAM-POSITIVE COCCI Alpha hemolytic Beta hemolytic |
Streptococcus pneumonia Streptococcus pyogenes
Staphylococcus aureus |
Lobar pneumonia, meningitis Impetigo, septic sore throat, scarlet fever Upper respiratory infections, boils, surgical infections, food poisoning, toxic shock syndrome |
Produces exotoxin causing skin rash Produces exotoxin causing food poisoning |
|
GRAM-NEGATIVE COCCI |
Neisseria gonorrhea
Neisseria meningitidis |
Gonorrhea. gonorrheal conjunctivitis Epidemic cerebrospinal meningitis |
Kidney-shaped diplococcic Kidney-shaped diplococcic |
|
GRAM-POSITIVE BACILLI Aerobic |
Corynebacterium diphtheriae |
Diphtheria |
Produces powerful exotoxin causing inflammation of mucosa and impairment of vital organs |
|
Aerobic. spore-forming |
Bacillus anthracis |
Anthrax (Chiefly in herbivorous animals,but also in man) |
Forms a capsule
|
|
Aerobic. acid-fast |
Mycobacterium tuberculosis M. bovis M. leprae |
Tuberculosis (man)
Tuberculosis (cattle and man) Leprosy (Hansen's Disease) |
|
|
Anaerobic, spore-forming |
Clostridium botulinum
C. tetan1 C. perfringens |
Food poisoning
Tetanus (lockjaw) Gas gangrene, food poisoning |
Produces powerful, lethal exotoxin Produces powerful, lethal exotoxin |
|
GRAM-NEGATIVE BACILLI |
Escherichia coli |
Traveler's diarrhea, urinary tract infection |
Many of these and other species are part of the normal flora of the adult intestinal tract, but pathogenic when introduced into other parts of the body |
|
|
Pseudomonas aeruginosa Klebsiella pneumonia Yersinia enterocolitica Salmonella typhi S. paratyphi Salmonella enteritidis (many serotypes) Shigella dysenteriae'
Shigella spp |
Burn wound infection Pneumonia Diarrhea Typhoid fever Paratyphoid fever
Acute gastroenteritis (Sal- moneliosis-“food poisoning”)
Bacillary dysentery |
Also produces a paralytic exotoxin |
Table 2-2. Pathogenic bacteria of public health importance. (continued)
|
IDENTIFICATION GROUP |
SPECIES |
CAUSATIVE AGENT |
REMARKS |
|
GRAM-NEGATIVE BACILLI (continued |
Vibrio cholerae
Vibrio parahemolyticus |
Cholera
Diarrhea |
Exototoxin causes "rice water" stool Food poisoning from contaminated shellfish. |
|
SMALL GRAM-NEGATIVE BACILL Non-motile, nonsporeforrning |
Brucella abortus B. suis B. melitensis Hemophilus influenzae |
Contagious abortion in animals; brucellosis (undulant fever) in man Pharyngitis. otitis. sinusitis, pneumonitis, or meningitis. |
Occurs in cattle 0ccurs in swine 0ccurs in sheep More common pathogen in children |
|
|
Bordetella pertussis
H. ducreyi Yersinia pestis Francisesella tularensis |
Whooping cough
Chancroid Plague Tularemia |
Encapsulated Exotoxin
A typical bacteria |
|
|
Chamydia trachomatis |
Urethritis. inclusion conjunctivitis. Trachoma. lymphogranuloma venereum |
A typical bacteria |
|
|
C. psittaci |
Psittacosis (parrot fever, ornithosis |
A typical bacterium, requires living host cell |
|
|
Mycoplasma (Ureplasma) |
Nongonococcal urethritis |
A typical bacterium, no cell wall requires special culture |
|
|
Mycoplasma pneumonia |
Primary, atypical pneumonia |
A typical bacterium, no cell wall requires special culture |
|
SPIROCHETES |
Treponema pallidum
Borrelia recurrent is |
Syphilis
Relapsing fever |
Does not stain with ordinary stain nor grow on artificial media |
|
|
Leptospirosa ichterohemorr hagiae (also L. canicola, L. autumnalis, and L. pomona) |
Leptospirosis (Weil’s disease, infectious jaundice) |
May be stained and cultured (chick embryo) |
Table 2-2. Pathogenic bacteria of public health importance. (concluded)
discussed in paragraph 2-9. The student should bear in mind that bacteria may fall into several groups; therefore, the appearance of a species under a particular heading in Table 2-2 does not imply that it may not be appropriately shown under another heading.
