| Organism |
Microbial Group |
Rod Length µm
|
Rod or Coccus Diameter µm
|
Source |
Significance |
|
|
|
|
|
|
| Absidia corymbifera |
Fungi |
|
3.8
|
Environmental |
Zygomycosis |
| Acetobacter Melanogenus |
Bacteria |
1.0-2.0
|
0.4-0.8
|
|
Strong beer/vinegar bacterium. |
| Acinetobacter |
Bacteria |
|
1.3
|
Environmental |
Opportunistic infections |
| Acremonium spp. |
Fungi |
|
2.5
|
Environmental |
Extrinsic Allergic Aveons |
| Actinomyces israelii |
Bacteria |
|
1.0
|
Humans |
Antinomycosis |
| Adenovirus |
Virus |
|
0.08
|
Humans |
Colds |
| Alcaligenes Viscolactis |
Bacteria |
0.8-2.6
|
0.6-1.0
|
|
Causes ropiness in milk. |
| Alkaligenes |
Bacteria |
|
0.75
|
Humans |
Opportunistic infections |
| Alternaria alternata |
Fungi |
|
14.4
|
Environmental |
Mycotoxicosis |
| Arenavirus |
Virus |
|
0.18
|
Rodents |
Hemorrhagic fever |
| Aspergillis spp. |
Fungi |
|
3.5
|
Environmental |
Aspergillosis, Volatile Organic Compound |
| Aureobasidium pullulans |
Fungi |
|
5
|
Environmental |
Chromomycosis |
| Bacillus anthracis |
Bacteria |
3.0-10.0
|
1.0-1.3
(1.1 average)
|
Environmental |
Causes anthrax in mammals |
| Bacillus Stearothermophilus |
Bacteria |
2.0-5.0
|
0.6-1.0
|
|
Biological indicator for steam sterilization |
| Bacillus subtilis |
Bacteria |
2.0-3.0
|
0.7-0.8
|
|
Biological indicator for ethylene oxide sterilization |
| Blastomyces dermatiitidis |
Fungi |
|
14
|
Environmental |
Blastomycosis |
| Bordetella pertussis |
Bacteria |
|
0.25
|
Humans |
Whooping cough |
| Botrytis cinera |
Fungi |
|
7
|
Environmental |
Extrinsic Allergic Aveons |
| Cardiobacterium |
Bacteria |
|
0.63
|
Humans |
Opportunistic infections |
| Chaetomium globosum |
Fungi |
|
5.5
|
Environmental |
Chromomycosis, Volatile Organic Compound |
| Chiamydia psittaci |
Bacteria |
|
0.3
|
Birds |
Psittacosis |
| Chlamydia pneumoiae |
Virus |
|
0.3
|
Humans |
Pneumonia |
| Cladosporium spp. |
Fungi |
|
9
|
Environmental |
Chromblastomycosis |
| Clostridium botulinum (B) |
Bacteria |
3.0-8.0
|
0.5-0.8
|
|
Produces exotin causes botulism |
| Clostridium Perinngens |
Bacteria |
4.0-8.0
|
1.0-1.5
|
|
Produces toxin causing food poisoning |
| Clostridium tetani |
Bacteria |
4.0-8.0
|
0.4-0.6
|
|
Produces exotoxin causing tetanus |
| Coccidioides immitis |
Fungi |
|
4
|
Environmental |
Coccidiodomycosis |
| Coronavirus |
Virus |
|
0.11
|
Humans |
Colds |
| Corynebacteria diphtheria |
Bacteria |
|
1.0
|
Humans |
Diphtheria |
| Coxiella burnetii |
Bacteria |
|
0.5
|
Cattle, sheep |
Q fever |
| Coxsackievirus |
Virus |
|
0.027
|
Humans |
Colds |
| Cryptococcus neoformans |
Fungi |
|
5.5
|
Environmental |
Cryptococcosis |
| Diplococcus Pneumoniae |
Bacteria |
|
0.5-1.25
|
|
Causes lobar pneumonia |
| Echovirus |
Virus |
|
0.028
|
Humans |
Colds |
| Emericella nidulans |
Fungi |
|
3.3
|
Environmental |
Mycotoxicosis, Volatile Organic Compound |
| Epicoccum nigrum |
Fungi |
|
20
|
Environmental |
Extrinsic Allergic Aveons |
| Erwina aroideae |
Bacteria |
2.0-3.0
|
0.5
|
|
Causes soft rot in vegetables. |
Escherichia Coli
(E Coli) |
Bacteria |
1.0-3.0
|
0.5
|
|
Indicator of fecal contamination in water. |
| Eurotium spp. |
Fungi |
|
5.8
|
Environmental |
Extrinsic Allergic Aveons |
| Exophiala jeanselmei |
Fungi |
|
2
|
Environmental |
Chromomycosis |
| Francisella tularensis |
Bacteria |
|
0.2
|
Wild animals |
Tularemia |
| Geomyces pannorum |
Fungi |
|
3
|
Environmental |
Extrinsic Allergic Aveons |
| Haemophilus influenzae |
Bacteria |
0.5-2.0
|
0.2-0.3
|
|
Causes influenza and acute respiratory infections |
| Haemophilus influenzae |
Bacteria |
|
0.43
|
Humans |
Meningitis, pneumonia |
| Haemophilus parainfluenzae |
Bacteria |
|
1
|
Humans |
Opportunistic infections |
| Hantavirus |
Virus |
|
0.07
|
Rodents |
Hantavirus |
| Helminthosporium |
Fungi |
|
12.5
|
Environmental |
Extrinsic Allergic Aveons |
| Histoplasma capsulatum |
Fungi |
|
3
|
Environmental |
Histoplasmosis |
| Influenza |
Virus |
|
0.1
|
Humans, birds |
Flu |
| Klebsielia pneumoniae |
Bacteria |
5
|
0.4-0.5
|
Environmental |
Opportunistic infections, causes pneumonia and other respiratory inflammation |
| Lactobacillus Delbrueckil |
Bacteria |
2.0-9.0
|
0.5-0.8
|
|
Causes souring of grain-mashes |
| Legionella pneumophia |
Bacteria |
|
0.6
|
Environmental |
Pontiac fever |
| Micromonospora faeni |
Actinomycetes |
|
1
|
Agricultural |
Farmers” lung, Hypersensitivity Pneumonitis |
| Micropolyspora faeni |
Actinomycetes |
|
0.69
|
Agricultural |
Farmers” lung, Hypersensitivity Pneumonitis |
| Moraxella catarrhalis |
Bacteria |
|
1.3
|
Humans |
Opportunistic infections |
| Moraxella lacunata |
Bacteria |
|
1
|
Humans |
Opportunistic infections |
| Morbillvirus |
Virus |
|
0.12
|
Humans |
Measles (rubeola) |
| Mucor plumbeus |
Fungi |
|
7.5
|
Environmental |
Mucormycosis |
| Mycobacterium avium |
Bacteria |
|
1.2
|
Environmental |
Cavitary pulmonary disorder |
| Mycobacterium intracellulare |
Bacteria |
|
1.2
|
Environmental |
Cavitary pulmonary disorder |
| Mycobacterium kansasli |
Bacteria |
|
0.86
|
Unknown |
Cavitary pulmonary disorder |
| Mycobacterium Tuberculosis |
Bacteria |
1.0-4.0
|
0.2-0.5
(0.86 average)
|
Humans |
Hard swelling of body tissues. TB |
| Mycoplasma pneumoniae |
Bacteria |
|
0.25
|
Humans |
Pneumonia |
| Mycoplasma pneumoniae (PPLO) |
Bacteria |
|
0.3-0.5
|
|
Smallest known free-living organism |
| Neisseria meningitidis |
Bacteria |
|
0.8
|
Humans |
Meningitis |
| Nocardia Brasilensis |
Actinomycetes |
|
1.5
|
Environmental |
Pulmonary mycetoma |
| Nocardiaasteroides |
Actinomycetes |
|
1.1
|
Environmental |
Nocardiosis |
| Paecilomyces variotii |
Fungi |
|
3
|
Environmental |
Mucormycosis |
| Paracoccidioides brasilensis |
Fungi |
|
23
|
Environmental |
Paracoccidioidomycosis |
| Parainfluenza |
Virus |
|
0.22
|
Humans |
Flu |
| Paramyxovirus |
Virus |
|
0.23
|
Humans |
Mumps |
| Parvovirus B19 |
Virus |
|
0.022
|
Humans |
Filth disease, anemia |
| Pediococcus acidilactci |
Bacteria |
|
0.6-1.0
|
|
Causes mash spoilage in brewing |
| Pediococcus Cerevisiae |
Bacteria |
|
1.0-1.3
|
|
Causes deterioration in beer |
| Penicillium spp. |
Fungi |
|
3.3
|
Environmental |
Mycotoxicosis, Volatile Organic Compound |
| Phialophora spp. |
Fungi |
|
1.5
|
Environmental |
Chromomycosis |
| Phoma spp |
Fungi |
|
3.3
|
Environmental |
Mucormycosis |
| Pneumocystis carinii |
Bacteria |
|
2
|
Environmental |
Pneumocystosis |
| Poxvirus – Vaccinia |
Virus |
|
0.23
|
Agricultural |
Cowpox |
| Pseudomonas aeruginosa |
Bacteria |
|
0.57
|
Environmental |
Opportunistic infections |
| Pseudomonas mallei |
Bacteria |
|
0.77
|
Environmental |
Opportunistic infections |
| Pseudomonas pseudomallei |
Bacteria |
|
0.57
|
Environmental |
Opportunistic infections |
| Pseudormonas diminuta |
Bacteria |
|
1.0 0.3
|
|
Test organism for retention 0.2 µm membranes |
| Rhinorvirus |
Virus |
|
0.023
|
Humans |
Colds |
| Rhizopus stolonifer |
Fungi |
|
8
|
Environmental |
Zygomycosis |
| Rhodoturula spp. |
Fungi |
|
14
|
Environmental |
Extrinsic Allergic Aveons |
| Salmonella enteritidis |
Bacteria |
2.0-3.0
|
0.6-0.7
|
|
Causes food poisoning |
| Salmonella enteritidis |
Bacteria |
2.0-3.0
|
0.6-0.7
|
|
Causes food poisoning |
| Salmonella hirschefeldii |
Bacteria |
1.0-2.5
|
0.3-0.5
|
|
Causes enteric fever |
| Salmonella typhimurium |
Bacteria |
|
1.0-1.5 0.5
|
|
Causes food poisoning in man |
| Salmonella typhosa |
Bacteria |
2.0-3.0
|
0.6-0.7
|
|
Causes typhoid fever |
| Sarcina maxima |
Bacteria |
|
4.0-4.5
|
|
Isolated from fermenting malt mash |
| Scopulariopsis spp. |
Fungi |
|
6
|
Environmental |
Onychomycosis |
| Serratia marcescens |
Bacteria |
0.5-1.0
|
0.5
|
|
Test organism for retention of 0.45 µm membranes |
| Serratia marcescens |
Bacteria |
|
1.3
|
Environmental |
Opportunistic infections |
| Shigella dysenteriae |
Bacteria |
1.0-3.0
|
0.4-0.6
|
|
Causes dysentery in man |
| Sporothrix schenckii |
Fungi |
|
6.5
|
Environmental |
Sporotrichosis |
| Stachybotrys spp. |
Fungi |
|
5.7
|
Environmental |
Stachybotryotoxicosis |
| Staphylococcus Aureus |
Bacteria |
|
0.8-1.0
|
Humans |
Causes pus forming infections, opportunistic infections |
| Streptoccous lactis |
Bacteria |
|
0.5-1.0
|
|
Contaminant in milk |
| Streptococcus pneumoniae |
Bacteria |
|
0.9
|
Humans |
Pneumonia, otitis media |
| Streptococcus pyogenes |
Bacteria |
|
0.6-1.0
(0.9 average)
|
Humans |
Causes pus forming infections, scarlet fever, pharyngitis |
| Thermoactinomyces sacchari |
Actinomycetes |
|
0.86
|
Agricultural |
Bagassosis |
| Thermoactinomyces vulgaris |
Actinomycetes |
|
1
|
Agricultural |
Farmers” lung, Hypersensitivity Pneumonitis |
| Thermomonspora viridis |
Actinomycetes |
|
0.6
|
Agricultural |
Farmers” lung, Hypersensitivity Pneumonitis |
| Togavirus |
Virus |
|
0.063
|
Humans |
Rubella (german measles) |
| Trichoderma spp. |
Fungi |
|
4.1
|
Environmental |
Mycotoxicosis, Volatile Organic Compound |
| Ulociadium spp. |
Fungi |
|
15
|
Environmental |
Extrinsic Allergic Aveons |
| Varicella-zoster |
Virus |
|
0.3
|
Humans |
Chickenpox |
| Wallemia sebi |
Fungi |
|
3
|
Environmental |
Extrinsic Allergic Aveons |
| Yersinia pestis |
Virus |
|
0.75
|
Humans |
Pheumonic plague |
