• Information
  1. Cocci
  2. Staphylococci
  3. Streptococcus
  4. Gram Negative Cocci
  5. Baccili
  6. Spirochetes
  7. Chlamydia
  8. Proteobacteria
  9. Rickettsia
  10. Mycoplasma
  11. Actinomycetes

A. Cocci

1. Gram Positive
   1. Staphylococci
   2. Streptococci (including pneumococcus, enterococci)
2. Gram Negative
   1. Neisseria
   2. Moraxella
3. Anaerobic Cocci
   1. Peptococcus and Peptostreptococcus (anaerobic streptococci)
   2. These are normal flora in the mouth
   3. Pathogenic in aspiration pneumonia

B. Staphylococci

1. Gram positive cocci in clusters
2. S. aureus: coagulase positive (pos)
   1. Frequent: cellulitis, line sepsis, endocarditis
   2. Hospital acquired pneumonia, Toxic Shock Syndrome
   3. Septic bursitis, arthritis; uncommon urinary tract infection (UTI)
3. S. epidermidis: coagulase negative (neg)
   1. Frequent: Line sepsis, Contaminant, prosthetic device infections
   2. Uncommon: Cellulitis, Endocarditis
4. S. saprophiticus: coagulase neg; common cause of UTI

C. Streptococcus

1. Gram positive in chains
   1. Classified by ability to lyse red blood cells (RBCs) in agar plates
   2. alpha-hemolytic: hemolysis leads to green (biliverdin) coloration of RBCs
   3. beta-hemolytic: hemolysis leads to clear coloration of RBCs
   4. Non-hemolytic: no hemolysis is observed
2. S. pyogenes (Group A)
   1. ß-hemolytic, pyogenic (pus forming)
   2. Frequent: pharyngitis, cellulitis
   3. Uncommon: Scarlet and Rheumatic fevers, Toxic Shock Syndrome, invasive infection
   4. Glomerulonephritis
3. S. agalactiae (Group B)
   1. alpha- and nonhemolytic
   2. Neonatal sepsis, meningitis
   3. Uncommon: cellulitis
   4. Highly pyogenic (pus forming) organism
4. S. viridans (Groups C and H) alpha- or nonhemolytic
   1. Species: S. sanguis, S. oralis (mitis), S. salivarius, S. mutans, S. anginosus (S. milleri)
   2. Common: Endocarditis [11]
   3. Uncommon: Line sepsis
5. Enterococci (Group D) - E. faecalis, E. faecium, others
6. S. faecalis (Group D, Enterococcus)
   1. alpha and nonhemolytic, ß-hemolytic
   2. Frequent: urinary tract infection (UTI), nosocomial bacteremia, abdominal infections
   3. Uncommon: endocarditis
7. S. faecium (Group D, Enterococcus)
   1. alpha-, non-, ß-hemolytic
   2. Frequent: hospital acquired UTI
   3. Increasing: antibiotic resistant infections in critically ill patients, bacteremia
8. Other Group D Streptococci
   1. Streptococcus bovis is most common
   2. Common: endocarditis, bacteremia associated with colon cancer
9. Group G Streptococci [7]
   1. Increasing incidence of bacteremia due to these organisms
   2. Typically occurs in older men
   3. Skin or soft tissue infection implicated in most cases
10. S. pneumoniae (Pneumococcus, Ungrouped)
    1. Encapsulated, alpha hemolytic diplococcus
    2. Common: pneumonia, otitis, meningitis, sinusitis
    3. Uncommon: endocarditis
    4. Most common cause of community acquired pneumonia
11. S. iniae - invasive organism associated with fish handling [2]

D. Gram Negative Cocci

1. Neisseria gonorrhoea
   1. More commonly: gonorrhea, pelvic inflammatory disease
   2. Less commonly: arthritis, pharyngitis
2. N. meningitidis
   1. More commonly: meningitis
   2. Less commonly: arthritis, purpura, sepsis
3. Moraxella catarrhalis
   1. Often found in normal lung as a colonizing organism
   2. Frequently causes exacerbations in COPD
   3. Also causes bronchitis and pneumonia
4. Francisella tularensis
   1. Types A and B, both found in North America and elsewhere
   2. Gram negative, aerobic coccobaccilus
   3. Causes tularemia with respiratory symptoms

E. Baccili

1. Aerobic Gram Positive Rods
   1. Bacillus ssp: uncommon cause of sepsis, wound and line infections (such as B. septicum)
   2. Bacillus anthraces: anthrax
   3. Bacillus cereus: food poisoning
   4. Coreynebacterium diphtheriae: children age 2-15 years; infects myocardium, nerves
   5. Listeria monocytogenes: infrequent cause of meningitis
   6. Nocardia asteroides: Filamentous bacteria, obligate aerobe, slow growth, atypical
2. Facultative Gram Negative Anaerobes
   1. Acinetobacter: diplococcobacilli, mainly nosocomial infections (pneumonia, UTI, bacteremia), often with multiple antibiotic resistance mechanisms [17]
   2. Bordetalla pertussis : Whooping cough. Coughing paroxysms with inspiratory whoop
   3. Brucella ssp: acute febrile illness in meat and animal workers
   4. Burkholderia mallei (formerly Pseudomonas): glanders, farcy (very rare) [6]
   5. Burkholderia pseudomallei: melioidosis, sepsis (mainloy in Asia, Australia), parotiditis [8]
   6. Enterobacter aerogenes: similar to Klebsiella
   7. Escherichia coli: Normal gut organism, UTI, toxigenic species cause diarrhea, hemolytic uremic syndrome (HUS) [12]
   8. Klebsiella pneumonia: bronchopneumonia, pleural abscess, abdominal infections, UTI
   9. Klebsiella oxytoca: antibiotic-associated hemorrhagic colitis [16]
   10. Legionella pneumophila: atypical pneumonia, lobular fibrinopurulent [1]
   11. Proteus mirabilis: frequently UTI; urea splitting due to phage infection (urine pH>8)
   12. Providentia: related to Proteus and Morganella, usually cause nosocomial UTI
   13. Pseudomonas aeruginosa: many nosocomial infections: UTI, lung, sepsis, wounds, burns
   14. Salmonella typhi: typhoid fever (GI mucosal necrosis), food poisoning
   15. Non-typhi Salmonella: diarrhea, particularly bloody type, food poisoning
   16. Serratia marcescene: pneumonia, UTI, others
   17. Shigella dysenteri: bacterial dysentery due to plasmid toxin
   18. Stenotrophomonas (Xanthomonas) maltophilia : pneumonia, sepsis, complicated UTI
   19. Yersinia enterocolitica: acute diarrhea, may be bloody
   20. Yersinia pestis: "plague", lymphoadenopathy, mild to fatal
3. Facultative Anaerobes, Comma Shaped Organisms
   1. Campylobacter jejuni: Relatively common cause of traveler's diarrhea, can induce small intestinal lymphoproliferative disease [9]
   2. Heliobacter pylori: flagellated, chronic gastritis, ulceration, enterocolitis, diarrhea, also associated with gastric cancer, MALT lymphomas [10], other diseases
   3. Vibrio cholerae: produces enterotoxin. Diarrhea with massive fluid secretions
4. Clostridia
   1. G+ Sporulating organisms (strict anaerobes)
   2. Clostridium botulinim : neuromuscular toxin, usually with food poisoning [3]
   3. C. difficile : pseudomembranous colitis (antibiotic associated)
   4. C. perfringens : gas gangrene (skin, internal organs, trauma) [4]
   5. C. tetani : tetanus toxin inhibiting nerve-muscle junctions
5. Other Strict Anaerobes
   1. Anaerobic Cocci (see above): normal oral flora
   2. Bacteroides fragillus: G-, normal gut flora; associated with thrombophlebitis [15]
   3. Fusobacterium ssp: normal G- oral flora
   4. Prevotella (formerly Bacteroides) ssp: G-, normally oral cavity

F. Spirochetes

1. Treponema pallidum
   1. Causative agent of Syphilis
   2. Four phases: chancre primary, secondary, latent quiescent, tertiary phase
2. Borrelia burgdorferi
   1. Causative agent of Lyme Disease
   2. Tick borne illness
   3. Symptoms: primary rash, arthritis, CNS symptoms, heart block
3. Borrelia recurrentis
   1. Relapsing fever, tick or louse borne
   2. Splenic disease
   3. May cause epidemic disease, especially in war
4. Leptospira interrogans [2,13]
   1. Rats and dogs carry organism, excreted in urine
   2. Exposure usually standing water, particularly in rural USA
   3. Clinical illness has septicemic and recovery (immune) phases
   4. Septicemic phase includes fever, rash, meningismus, myositis and uveitis
   5. May present with conjunctival injection, isolated hyperbilirubinemia, renal failure, fever [13]
   6. Four fold increase in serological test for antibodies
   7. Microscopic (darkfield) exam of urine
   8. High dose doxycycline or penicillin is treatment

G. Chlamydia

1. Chlamydia trachomatis
   1. Sexually Transmitted Disease
   2. Cause of non-gonoccal urethritis, pelvic inflammatory disease, prostatitis
2. Chlamydia pneumoniae
   1. Frequent cause of pneumonia in young adults
   2. Formerly called the "TWAR" agent
3. Chlamydia psittaci
   1. Frequent cause of pneunomia in pigeon breeders, others with pet birds
   2. Atypical pneumonia pattern
   3. Infected birds die as well

H. Proteobacteria

1. alpha2 Subdivision [14]
   1. Brucella
   2. Rickettsia
   3. Bartonella
   4. Agrobacterium
   5. Ochrobactrum
   6. Rhodobacter
   7. Rhizobium

I. Rickettsia

1. Rickettsia rickettsiae: Rocky mountain spotted fever
2. Other Rickettsia - R. helvetica, R. typhis, R. conorii [5]
3. Scrub typhus
4. Ehrlichia chaffeensis
   1. Causative agent of Erilichosis, a toxic-shock like syndrome
   2. Usually occurs in Western USA

J. Mycoplasma

1. Mycoplasma pneumoniae : most common "atypical" pneumonia
2. Mycoplasma genitalium
3. Mycoplasma hominus
4. Ureaplasma urealyticum : urinary tract infection, symptomatic in females

K. Actinomycetes

1. Nocardia asteroides
   1. G+ aerobic organism
   2. Weakly acid fast
   3. Causes pulmonary disease, particularly in immunocompromised persons
   4. Infections may disseminate
2. Actinomyces israelii
   1. Related to nocardia
   2. Usually cause: chronic anaerobic supperative infections
   3. Neck, lung, or abdomen
3. Tropherema whippelii

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5. Nilsson K, Lindquist O, Pahlson C. 1999. Lancet. 354(9185):1169
6. Srinivasan A, Kraus CN, DeShazer D, et al. 2001. NEJM. 345(4):256
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13. Kaul DR, Flanders SA, Saint S. 2005. NEJM. 352(18):1914 (Case Discussion)
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15. Kasper DL, Sahani D, Misdraji J. 2005. NEJM. 353(7):713 (Case Record)
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17. Munoz-Price LS and Weinstein RA. 2008. NEJM. 358(12):1271