Table 2. Important Bacteria that Are Pathogens of Humans

Bacterial pathogen	Disease(s)	Transmission
Gram-negative bacteria
Escherichia coli	Gastroenteritis, urinary tract infections, neonatal meningitis	F W E
E. coli O157:H7	Diarrhea, hemolytic uremic syndrome (HUS)	F
Salmonella enterica	Gastroenteritis	F W
Salmonella typhi	Typhoid fever	F W
Shigella dysenteriae	Bacillary dysentery	F W
Yersina pestis	Bubonic plague	IV
Pseudomonas aeruginosa	Opportunistic infections, swimmer�s ear, hot tub itch, cellulitis, pneumonia, more	S W C HA E
Vibrio cholerae	Asiatic cholera	W
Bordetella pertussis	Whooping cough	RC
Haemophilus influenzae	Meningitis, pneumonia, sinusitis	RC
Helicobacter pylori	Gastric and duodenal ulcers	F?
Campylobacter jejuni	Gastroenteritis	F W
Neisseria gonorrhoeae	Gonorrhea	S C
Neisseria meningitidis	Meningococcemia and meningitis	R C E
Brucella abortus	Undulant fever	IA M
Bacteroides fragilis	Anaerobic infections	E
Gram-positive bacteria
Staphylococcus aureus	Food poisoning, wound infections, toxic shock syndrome, more	F C E HA IA
Streptococcus pyogenes	Strep throat, scarlet fever, mastitis, necrotizing fasciitis, more	C
Streptococcus pneumoniae	Pneumonia, otitis media, meningitis	RC E
Bacillus anthracis	Anthrax	S IA
Bacillus cereus	Food poisoning	F
Clostridium tetani	Tetanus	S
Clostridium perfringens	Food poisoning, gas gangrene, uterine infections	F S E
Clostridium botulinum	Botulism, infant botulism	F
Clostridium difficile	Antibiotic-associated diarrhea, pseudomembranous colitis	C HA E
Corynebacterium diphtheriae	Diphtheria	RC
Listeria monocytogenes	Listeriosis	F
Not typed by Gram stain
Mycobacterium tuberculosis	TB (tuberculosis)	RC M
Mycobacterium leprae	Leprosy	C
Chlamydia trachomatis	Chlamydia, lymphogranuloma venereum, trachoma	SC C
Chlamydia pneumoniae	Pneumonia	RC
Mycoplasma pneumoniae	Atypical pneumonia	RC
Rickettisas	Rickettsiosis: typhus, RMSF	IV
Treponema pallidum	Syphilis	SC
Borrelia burgdorferi	Lyme disease	IV

KEY TO TRANSMISSION. C = Contact   E = Endogenous   F = Food borne   HA = Hospital Acquired
IA = Infected Animal   IV = Insect Vector   M = Milk   RC = Respiratory Contact   SC = Sexual Contact
S = Soil   W = Water

Table 3. Bacterial Diseases of Humans by Anatomical Site or Type

Infections of the oral cavity
Dental caries: Streptococcus mutans, S. oralis, S. sanguis, S. gordonii
Gingivitis
Periodontal disease

GI Tract
Gastric and duodenal ulcers: Helicobacter pylori
Gastroenteritis: Salmonella, Campylobacter, E. coli
Dysentery: Shigella
Antibiotic�associated diarrhea and pseudomembranous colitis: Clostridium difficile
Asiatic cholera: Vibrio cholerae
Food poisoning
    Staphylococcus aureus
    Bacillus cereus
    Clostridium perfringens
    Clostridium botulinum
Food infections
    Salmonella
    E. coli O157:H7
    Campylobacter jejuni
    Listeria monocytogenes: Listeriosis

Respiratory Tract
Sinusitis
    Haemophilus influenzae
    Pseudomonas aeruginosa
Strep throat: Streptococcus pyogenes
Diphtheria: Corynebacterium diphtheriae
Pneumonia
    Streptococcus pneumoniae
    Staphylococcus aureus
    Pseudomonas aeruginosa
    Haemophilus influenzae
    Chlamydia pneumoniae
    Mycoplasma pneumoniae
Whooping cough: Bordetella pertussis
Tuberculosis: Mycobacterium tuberculosis

Sexually-Transmitted Disease
Chlamydia: Chlamydia trachomatis
Gonorrhea: Neisseria gonorrhoeae
Syphilis: Treponema pallidum

Urinary Tract Infections
    E. coli
    Pseudomonas aeruginosa
    Staphylococcus aureus

Meningitis
    Neisseria meningitidis
    Haemophilus influenzae
    Streptococcus pneumoniae
    Escherichia coli

Otitis
    Otitis externa: Pseudomonas aeruginosa
    Otitis media: Streptococcus pneumoniae, Haemophilus influenzae

Skin
Acne, boils, pimples, impetigo: Staphylococcus aureus
Hot tub itch, folliculitis, cellulitis: Pseudomonas aeruginosa
Necrotizing fasciitis: Streptococcus pyogenes

Zoonoses
Anthrax: Bacillus anthracis
Brucellosis: Brucella abortus
Leptospirosis: Leptospira

Arthropod borne
Lyme disease: Borrelia burgdorferi
Ehrlichiosis: Ehrlichia
Rickettsiosis (Typhus, Rocky Mountain Spotted Fever): Rickettsias
Plague: Yersinia pestis

Toxinoses
Toxic shock syndrome, Scalded skin syndrome: Staphylococcus aureus
Scarlet fever: Streptococcus pyogenes
Hemolytic Uremic Syndrome (HUS): E. coli O157:H7
Diphtheria: Corynebacterium diphtheriae
Anthrax: Bacillus anthracis
Tetanus: Clostridium tetani
Botulism: Clostridium botulinum

Hospital-acquired (nosocomial) infections
MRSA (methicillin-resistant Staphylococcus aureus)
Escherichia coli
Pseudomonas aeruginosa
Clostridium difficile