|Classification and external resources|
Although most bacteria are harmless or often beneficial, several are pathogenic. One of the bacterial diseases with the highest disease burden is tuberculosis, caused by the bacterium Mycobacterium tuberculosis, which kills about 2 million people a year, mostly in sub-Saharan Africa. Pathogenic bacteria contribute to other globally important diseases, such as pneumonia, which can be caused by bacteria such as Streptococcus and Pseudomonas, and foodborne illnesses, which can be caused by bacteria such as Shigella, Campylobacter, and Salmonella. Pathogenic bacteria also cause infections such as tetanus, typhoid fever, diphtheria, syphilis, and leprosy. Pathogenic bacteria are also the cause of high infant mortality rates in developing countries.
- 1 Diseases
- 2 Mechanisms
- 3 Treatment
- 4 List of genera of pathogenic bacteria and microscopy features
- 5 List of species of pathogenic bacteria and clinical characteristics
- 6 See also
- 7 References
- 8 External links
Each species has specific effect and causes symptoms in people who are infected. Some, if not most people who are infected with a pathogenic bacteria do not have symptoms. Immuno-compromised individuals are more susceptible to pathogenic bacteria.
Some pathogenic bacteria cause disease under certain conditions, such entry through the skin via a cut, through sexual activity or an compromised immune function.
Streptococcus and Staphylococcus are part of the normal skin microbiota and typically reside on healthy skin or in the nasopharangeal region. Yet these species can potentially initiate skin infections. They are also able to cause sepsis, pneumonia, meningitis. These infections can become quite serious creating a systemic inflammatory response resulting in massive vasodilation, shock, and death.
Other bacteria are opportunistic pathogens and cause disease mainly in people suffering from immunosuppression or cystic fibrosis Examples of these opportunistic pathogens include Pseudomonas aeruginosa,Burkholderia cenocepacia, and Mycobacterium avium.
Obligate intracellular parasites (e.g. Chlamydophila, Ehrlichia, Rickettsia) have the ability to only grow and replicate inside other cells. Even these intracellular infections may be asymptomatic, requiring an incubation period. An example of this Rickettsia which causes typhus. Another causes Rocky Mountain spotted fever.
Other groups of intacellular bacterial pathogens include: Salmonella, Neisseria, Brucella, Mycobacterium, Listeria, Francisella, Legionella, and Yersinia pestis. These can exist intracellularly, but can exist outside of host cells.
Infections in specific tissue
Bacterial pathogens often cause infection in specific areas of the body. Others are generalists.
- Bacterial vaginosis is caused by bacteria that change the vaginal microbiota caused by an overgrowth of bacteria that crowd out the Lactobacilli species that maintain healthy vaginal microbial populations.
- Other non-bacterial vaginal infections include: yeast infection (candidiasis), Trichomonas vaginalis (trichomoniasis).
- Bacterial meningitis is a bacterial inflammation of the meninges, that is, the protective membranes covering the brain and spinal cord.
- Bacterial pneumonia is a bacterial infection of the lungs.
- Urinary tract infection is predominantly caused by bacteria. Symptoms include the strong and frequent sensation or urge to urinate, pain during urination, and urine that is cloudy. The main causal agent is Escherichia coli. Urine is typically sterile but contains a variety of salts, and waste products. Bacteria can ascend into the bladder or kidney and causing cystitis and nephritis.
- Bacterial gastroenteritis is caused by enteric, pathogenic bacteria. These pathogenic species are usually distinct from the usually harmless bacteria of the normal gut flora. But a different strain of the same species may be pathogenic. The distinction is sometimes difficult as in the case of Escherichia.
- Bacterial skin infections include:
- Impetigo is a highly contagious bacterial skin infection commonly seen in children. It is caused by Staphylococcus aureus, and Streptococcus pyogenes.
- Erysipelas is an acute streptococcus bacterial infection of the deeper skin layers that spreads via with lymphatic system.
- Cellulitis is a diffuse inflammation of connective tissue with severe inflammation of dermal and subcutaneous layers of the skin. Cellulitis can be caused by normal skin flora or by contagious contact, and usually occurs through open skin, cuts, blisters, cracks in the skin, insect bites, animal bites, burns, surgical wounds, intravenous drug injection, or sites of intravenous catheter insertion. In most cases it is the skin on the face or lower legs that is affected, though cellulitis can occur in other tissues.
Iron is required for humans, as well as the growth of most bacteria. To obtain free iron, some pathogens secrete proteins called siderophores, which take the iron away from iron-transport proteins by binding to the iron even more tightly. Once the iron-siderophore complex is formed, it is taken up by siderophore receptors on the bacterial surface and then that iron is brought into the bacterium.
Once pathogens attach to host cells, they can cause direct damage as the pathogens use the host cell for nutrients and produce waste products. As pathogens multiply and divide inside host cells, the cells usually rupture and the intercellular bacteria are released. Some bacteria such as E. coli, Shigella, Salmonella, and Neisseria gonorrhoeae, can induce host epithelial cells to engulf them in a process resembling phagocytosis. The pathogens can then disrupt host cells as they pass through them and be extruded from host cells by a reverse phagocytosis process, enabling them to enter other host cells. Some bacteria can also penetrate host cells by excreting enzymes and by their own motility; such penetration can can itself damage the host cell.
Toxins are poisonous substances that are produced by certain microorganisms and are often the primary factor contributing to the pathogenic properties of the microorganisms. Endotoxins are the lipid portions of lipopolysaccharides that are part of the outer membrane of the cell wall of gram negative bacteria. Endotoxins are released when the bacteria lyses, which is why after antibiotic treatment symptoms can at first worsen as the bacteria are killed and they release their endotoxins. Exotoxins are proteins produced inside pathogenic bacteria as part of their growth and metabolism, most common in gram positive bacteria. The exotoxins are released when the bacteria die and the cell wall breaks apart. Exotoxins are highly specific in the effects on body tissues and work by destroying particular parts of the host cell or by inhibiting certain metabolic functions. Exotoxins are among the most lethal known substances, only 1 mg of the botulinum exotoxin is enough to kill one million guinea pigs. Diseases caused this way are often caused by minute amounts of exotoxins, not by the bacteria themselves.
- See also overview list below
Bacterial infections may be treated with antibiotics, which are classified as bacteriocidal if they kill bacteria or bacteriostatic if they just prevent bacterial growth. There are many types of antibiotics and each class inhibits a process that is different in the pathogen from that found in the host. For example, the antibiotics chloramphenicol and tetracyclin inhibit the bacterial ribosome but not the structurally different eukaryotic ribosome, so they exhibit selective toxicity. Antibiotics are used both in treating human disease and in intensive farming to promote animal growth. Both uses may be contributing to the rapid development of antibiotic resistance in bacterial populations. Phage therapy can also be used to treat certain bacterial infections. Infections can be prevented by antiseptic measures such as sterilizing the skin prior to piercing it with the needle of a syringe and by proper care of indwelling catheters. Surgical and dental instruments are also sterilized to prevent infection by bacteria. Disinfectants such as bleach are used to kill bacteria or other pathogens on surfaces to prevent contamination and further reduce the risk of infection. Bacteria in food are killed by cooking to temperatures above 73 °C (163 °F).
List of genera of pathogenic bacteria and microscopy features
|Genus||Species||Gram staining||Shape||Oxygen requirement||Intra/Extracellular|
|Borrelia||Negative, stains poorly||spirochete||Anaerobic||Extracellular|
|Chlamydia and Chlamydophila||(not Gram-stained)||Small, round, ovoid||Facultative or strictly aerobic||Obligate intracellular|
|Clostridium||Positive||Large, blunt-ended rods||Obligate anaerobic||extracellular|
|Corynebacterium||Positive (unevenly)||bacilli||Mostly facultative anaerobic||extracellular|
|Escherichia||Negative||Bacillus||Facultative anaerobic||extracellular or intracellular|
|Francisella||Negative||coccobacillus||strictly aerobic||Facultative intracellular|
|Haemophilus||Negative||coccobacilli to long and slender filaments||extracellular|
|Legionella||Negative, stains poorly||cocobacilli||aerobic||facultative intracellular|
|Leptospira||Negative, stains poorly||Spirochete||Strictly aerobic||extracellular|
|Listeria||Positive, darkly||Slender, short rods||Facultative Anaerobic||intracellular|
|Mycobacterium||(none)||Long, slender rods||aerobic||extracellular|
|Mycoplasma||(none)||'fried egg' appearance, no cell wall||Mostly facultative anaerobic; M. pneumoniae strictly aerobic||extracellular|
|Neisseria||Negative||Kidney bean-shaped||aerobic||Gonococcus: facultative intracellular
N. meningitidis: extracellular
|Rickettsia||Negative, stains poorly||Small, rod-like coccobacillary||Aerobic||Obligate intracellular|
|Salmonella||Negative||Bacillus shape||Facultative anaerobica||Facultative intracellular|
|Staphylococcus||Positive, darkly||Round cocci||Facultative anaerobic||extracellular, facultative intracellular|
|Streptococcus||Positive||ovoid to spherical||Facultative anaerobic||extracellular|
|Treponema||Negative, stains poorly||Spirochete||Aerobic||extracellular|
|Ureaplasma||Stains poorly||indistinct, 'fried egg' appearance, no cell wall||anaerobic||extracellular|
|Vibrio||Negative||Spiral with single polar flagellum||Facultative anaerobic||extracellular|
|Yersinia||Negative, bipolarly||Small rods||Facultative Anaerobe||Intracellular|
List of species of pathogenic bacteria and clinical characteristics
This is description of the more common genera and species presented with their clinical characteristics and treatments.
|Actinomyces israelii||Oral flora||Actinomycosis||Prolonged penicillin G and drainage|
|Bacillus anthracis||In early infection:
|Bacteroides fragilis||Gut flora||Abscesses in gastrointestinal tract, pelvic cavity and lungs||metronidazole||Wound care
Contact with respiratory droplets expelled by infected human hosts.
|Macrolides such as erythromycin, before paroxysmal stage|
Early stages of Lyme disease:
Chronic Lyme disease:
|Chlamydia||C. pneumoniae||Atypical pneumonia||None|
|Chlamydophila psittaci||Inhalation of dust with secretions or feces from birds (e.g. parrots)||Psittacosis||-|
|Clostridium||C. botulinum||Spores from soil, persevere in canned food, smoked fish and honey||
Proper food preservation techniques
|C. difficile||Fecal bacteriotherapy
|C. perfringens||Gas gangrene:||Appropriate food handling|
No vaccine Hand washing and other nosocomial prevention
|Escherichia||E. coli (generally)||UTI:
(resistance-tests are required first)
|(no vaccine or preventive drug)|
|Enterotoxigenic E. coli (ETEC)|
|Enteropathogenic E. coli||
|Enteroinvasive E.coli (EIEC)|
|Enterohemorrhagic (EHEC), including E. coli O157:H7||
(resistance-tests are required first)
|Helicobacter pylori||(No vaccine or preventive drug)|
|Legionella pneumophila||(no vaccine or preventive drug)
||Vaccine not widely used
Prevention of exposure
|Listeria monocytogenes||(no vaccine)
Standard "short" course:
|Neisseria||N. gonorrhoeae||Uncomplicated gonorrhea:
|Pseudomonas aeruginosa||Opportunistic; Infects damaged tissues or people with immunodeficiency.||Pseudomonas infection:||(no vaccine)|
|Nocardia asteroides||In soil||Nocardiosis||TMP/SMX|
|Rickettsia rickettsii||(no preventive drug or approved vaccine)|
|Other Salmonella species||
||(No vaccine or preventive drug)|
|Staphylococcus||aureus||Coagulase-positive staphylococcal infections:||(no vaccine or preventive drug)
|epidermidis||Human flora in skin, anterior nares and mucous membranes||None|
|saprophyticus||Part of normal vaginal flora||None|
|Streptococcus||agalactiae||Human flora in vagina, urethral mucous membranes, rectum||None|
|viridans||Oral flora, penetration through abrasions||Penicillin G|
|Treponema pallidum||No preventive drug or vaccine|
- Santosham, Mathuram; Chan, Grace J.; Lee, Anne CC; Baqui, Abdullah H.; Tan, Jingwen; Black, Robert E. (2013). "Risk of Early-Onset Neonatal Infection with Maternal Infection or Colonization: A Global Systematic Review and Meta-Analysis". PLoS Medicine 10 (8): e1001502. doi:10.1371/journal.pmed.1001502. ISSN 1549-1676.
- Fish DN (February 2002). "Optimal antimicrobial therapy for sepsis". Am J Health Syst Pharm 59 (Suppl 1): S13–9. PMID 11885408.
- Heise E (1982). "Diseases associated with immunosuppression". Environ Health Perspect 43: 9–19. doi:10.2307/3429162. JSTOR 3429162. PMC 1568899. PMID 7037390.
- Saiman L (2004). "Microbiology of early CF lung disease". Paediatr Respir Rev 5 (Suppl A): S367–9. doi:10.1016/S1526-0542(04)90065-6. PMID 14980298.
- Belland R, Ouellette S, Gieffers J, Byrne G (2004). "Chlamydia pneumoniae and atherosclerosis". Cell Microbiol 6 (2): 117–27. doi:10.1046/j.1462-5822.2003.00352.x. PMID 14706098.
- Terri Warren, RN (2010). "Is It a Yeast Infection?". Retrieved 2011-02-23.
- Ferris DG, Nyirjesy P, Sobel JD, Soper D, Pavletic A, Litaker MS (March 2002). "Over-the-counter antifungal drug misuse associated with patient-diagnosed vulvovaginal candidiasis". Obstetrics and Gynecology 99 (3): 419–425. doi:10.1016/S0029-7844(01)01759-8. PMID 11864668.
- "Urinary Tract Infections". Retrieved 2010-02-04.
- "Adult Health Advisor 2005.4: Bacteria in Urine, No Symptoms (Asymptomatic Bacteriuria)". Archived from the original on 2007-07-12. Retrieved 2007-08-25.
- NHS Impetigo
- Kumar, Vinay; Abbas, Abul K.; Fausto, Nelson; & Mitchell, Richard N. (2007). Robbins Basic Pathology (8th ed.). Saunders Elsevier. pp. 843 ISBN 978-1-4160-2973-1
- "erysipelas" at Dorland's Medical Dictionary
- "cellulitis" at Dorland's Medical Dictionary
- Tortota, Gerard (2013). Microbiology an Introduction. ISBN 978-0-321-73360-3.
- Yonath A, Bashan A (2004). "Ribosomal crystallography: initiation, peptide bond formation, and amino acid polymerization are hampered by antibiotics". Annu Rev Microbiol 58: 233–51. doi:10.1146/annurev.micro.58.030603.123822. PMID 15487937.
- Khachatourians GG (November 1998). "Agricultural use of antibiotics and the evolution and transfer of antibiotic-resistant bacteria". CMAJ 159 (9): 1129–36. PMC 1229782. PMID 9835883.
- Keen, E. C. (2012). "Phage Therapy: Concept to Cure". Frontiers in Microbiology 3. doi:10.3389/fmicb.2012.00238. PMC 3400130. PMID 22833738.
- Unless else specified in boxes then ref is: Fisher, Bruce; Harvey, Richard P.; Champe, Pamela C. (2007). Lippincott's Illustrated Reviews: Microbiology (Lippincott's Illustrated Reviews Series). Hagerstown, MD: Lippincott Williams & Wilkins. pp. 332–353. ISBN 0-7817-8215-5.
- Kurzynski TA, Boehm DM, Rott-Petri JA, Schell RF, Allison PE (1988). "Comparison of modified Bordet-Gengou and modified Regan-Lowe media for the isolation of Bordetella pertussis and Bordetella parapertussis". J. Clin. Microbiol. 26 (12): 2661–3. PMC 266968. PMID 2906642.
- Fisher, Bruce; Harvey, Richard P.; Champe, Pamela C. (2007). Lippincott's Illustrated Reviews: Microbiology (Lippincott's Illustrated Reviews Series). Hagerstown, MD: Lippincott Williams & Wilkins. pp. 332–353. ISBN 0-7817-8215-5.
- Baron, Samuel (1996). Medical Microbiology, 4th edition. University of Texas Medical Branch at Galveston, Galveston, Texas. ISBN 0-9631172-1-1.
- Rollins, David M. (2000). "BSCI424 Laboratory Media". University of Maryland. Retrieved 2008-11-18.
- Cain, Donna (January 14, 2015). "MacConkey Agar (CCCCD Microbiology". Collin College.
- Gunn, B.A. "Chocolate agar: A differential medium for gram positive cocci". PubMed. Retrieved 28 September 2012.
- Stevenson TH, Castillo A, Lucia LM, Acuff GR (2000). "Growth of Helicobacter pylori in various liquid and plating media". Lett. Appl. Microbiol. 30 (3): 192–6. doi:10.1046/j.1472-765x.2000.00699.x. PMID 10747249.
- Johnson RC, Harris VG (1967). "Differentiation of Pathogenic and Saprophytic Leptospires I. Growth at Low Temperatures". J. Bacteriol. 94 (1): 27–31. PMC 251866. PMID 6027998.
- "Thayer Martin Agar (Modified) Procedure" (PDF). University of Nebraska-Medical Center, Clinical Laboratory Science Program. Retrieved 2015-05-03.
- Allen, Mary E. (2005). "MacConkey Agar Plates Protocols". American Society for Microbiology. Created: 30 September 2005. Last update: 01 April 2013
- "Hektoen Enteric Agar". Austin Community College District. Retrieved 2015-05-03.
- Cassell GH, Waites KB, Crouse DT, Rudd PT, Canupp KC, Stagno S, Cutter GR (1988). "Association of Ureaplasma urealyticum infection of the lower respiratory tract with chronic lung disease and death in very-low-birth-weight infants". Lancet 2 (8605): 240–5. doi:10.1016/s0140-6736(88)92536-6. PMID 2899235.
- Pfeffer, C.; Oliver, J.D. (2003). "A comparison of thiosulphate-citrate-bile salts-sucrose (TCBS) agar and thiosulphate-chloride-iodide (TCI) agar for the isolation of Vibrio species from estuarine environments". Letters in Applied Microbiology 36 (3): 150–151. doi:10.1046/j.1472-765X.2003.01280.x. PMID 12581373.
- "Yersinia pestis" (PDF). Wadsworth Center. 2006.
- "Bacteria Table" (PDF). Creighton University School of Medicine. Retrieved 2015-05-03.
- "Anthrax in animals". Food and Agriculture Organization. 2001.
- "CDC Anthrax Q & A: Treatment". Retrieved 4 April 2011.
- "FDA approves raxibacumab to treat inhalational anthrax". Retrieved 14 December 2012.
- Itzhak Brook (Jan 28, 2014). "Bacteroides Infection Follow-up". Medscape. Retrieved 2015-09-25.
- "ESCHERICHIA COLI". Public Health Agency of Canada. 2012-04-30. Retrieved 2015-06-02.
- Ryan, KJ; Ray, CG, eds. (2004). Sherris Medical Microbiology (4th ed.). McGraw Hill. ISBN 0-8385-8529-9.
- "Klebsiella pneumoniae in Healthcare Settings". Centers for Disease Control and Prevention. Page last reviewed: November 24, 2010. Page last updated: August 27, 2012
- Institut Pasteur Press Office - Vaccine against shigellosis (bacillary dysentery):a promising clinical trial 15 January 2009. Retrieved on 27 February 2009
- Levinson, W. (2010). Review of Medical Microbiology and Immunology (11th ed.). pp. 94–9.
- Zhou D, Han Y, Yang R; Han; Yang (2006). "Molecular and physiological insights into plague transmission, virulence and etiology". Microbes Infect. 8 (1): 273–84. doi:10.1016/j.micinf.2005.06.006. PMID 16182593.
- Wagle PM. (1948). "Recent advances in the treatment of bubonic plague". Indian J Med Sci 2: 489–94.
- Meyer KF. (1950). "Modern therapy of plague". JAMA 144 (12): 982–5. doi:10.1001/jama.1950.02920120006003. PMID 14774219.
- Kilonzo BS, Makundi RH, Mbise TJ.; Makundi; Mbise (1992). "A decade of plague epidemiology and control in the Western Usambara mountains, north-east Tanzania". Acta Tropica 50 (4): 323–9. doi:10.1016/0001-706X(92)90067-8. PMID 1356303.
- Bubeck SS, Dube PH (September 2007). "Yersinia pestis CO92ΔyopH Is a Potent Live, Attenuated Plague Vaccine". Clin. Vaccine Immunol. 14 (9): 1235–8. doi:10.1128/CVI.00137-07. PMC 2043315. PMID 17652523.
- Bacterial Pathogen Pronunciation by Neal R. Chamberlain, Ph.D at A.T. Still University
- Raw Living Radio Interviews Dr Robert Cassar as part of a 3 Show Series in HD 2014 from the EarthShiftProject.com an Educational and Informational Research Organization welcoming More participation from fellow Student Researchers, ...We want to Include More Student Researchers Including You!]
- Pathogenic bacteria genomes and related information at PATRIC, a Bioinformatics Resource Center funded by NIAID