A Few Bacteria to Know: Difference between revisions
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| ''Bacillus cereus'' |
| ''Bacillus cereus'' |
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| Food poisoning |
| Food poisoning; often contaminant |
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| Other ''Bacillus'' species |
| Other ''Bacillus'' species |
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| Often contaminant |
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| Contaminant |
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| ''Listeria monocytogenes'' |
| ''Listeria monocytogenes'' |
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Revision as of 15:24, 29 October 2019
When identifying a bacterium, the first step is Gram stain, which can tell us whether it has a Gram-positive or Gram-negative cell wall, and can give us information about the size and shape (bacilli or cocci, usually). Everyone needs to know how to interpret a Gram-stain report, since it is still one of the first pieces of information we get about a bacterial infection.
Gram-positive Bacteria
Cocci
Clusters or Groups
| Species | Clinical Syndromes |
|---|---|
| Staphylococcus aureus | Purulent skin and soft tissue infections, abscesses, endocarditis, HAP/VAP, food poisoning |
| Coagulase-negative Staphylococci | Line infections, UTIs (S. saprophyticus) |
Pairs or Chains
| Species | Clinical Syndromes |
|---|---|
| Streptococcus pyogenes/GAS | Cellulitis |
| Other Lancefield-group Streptococci | Cellulitis, UTIs, endocarditis |
| Streptococcus pneumoniae | Pneumonia, meningitis |
| Enterococcus spp. | UTIs, line infections, endocarditis |
Bacilli
| Species | Clinical Syndromes |
|---|---|
| Clostridium difficile/tetani/botulinum/perfringens | Diarrhea/tetanus/botulism/nec. fasc. |
| Bacillus cereus | Food poisoning; often contaminant |
| Other Bacillus species | Often contaminant |
| Listeria monocytogenes | Meningitis |
Gram-negative Bacteria
Bacilli
Enterobacteraceae (Poop!)
| Species | Clinical Syndromes |
|---|---|
| Yersinia/Shigella/Salmonella/E.coli O157:H7/Campylobacter | Infectious diarrhea/dysentery |
| Escherichia coli | Intraabdominal infections, UTIs, HAP/VAP |
| Klebsiella spp. | Intraabdominal infections, UTIs, HAP/VAP |
| Proteus spp. | Intraabdominal infections, UTIs, HAP/VAP |
| SPICE bugs | Very resistant, generally use carbapenems empirically |
Others
| Species | Clinical Syndromes |
|---|---|
| Pseudomonas aeruginosa | Otitis externa, hot-tub folliculitis, UTIs, pneumonias... very resistant to antibiotics |
Cocci
| Species | Clinical Syndromes |
|---|---|
| Neisseria meningitidis | Meningitis |
| Neisseria gonorrhoeae | Urethritis, PID, disemminated gonococcal infection |
Miscellaneous Bacteria
| Feature | Species | Clinical Syndromes |
|---|---|---|
| Acid-fast bacilli | Mycobacterium tuberculosis | Pulmonary tuberculosis, extrapulmonary tuberculosis |
| Spirochete | Treponema pallidum | Syphilis (primary, secondary, tertiary) |
| Spirochete | Borrelia burgdorferi | Lyme disease |
| Intracellular | Chlamydia trachomatis | Urethritis, PID |
| Intracellular | Chlamydia pneumophila | Atypical pneumonia |
| No cell wall | Mycoplasma pneumoniae | Atypical pneumonia |