Pathogenic bacteria are bacteria that can cause disease.[1] This article focuses on the bacteria that are pathogenic to humans. Most species of bacteria are harmless and are often beneficial but others can cause infectious diseases. The number of these pathogenic species in humans is estimated to be fewer than a hundred.[2] By contrast, several thousand species are part of the gut flora present in the digestive tract.[citation needed]
The body is continually exposed to many species of bacteria, including beneficial commensals, which grow on the skin and mucous membranes, and saprophytes, which grow mainly in the soil and in decaying matter. The blood and tissue fluids contain nutrients sufficient to sustain the growth of many bacteria. The body has defence mechanisms that enable it to resist microbial invasion of its tissues and give it a natural immunity or innate resistance against many microorganisms.
Pathogenic bacteria are specially adapted and endowed with mechanisms for overcoming the normal body defences, and can invade parts of the body, such as the blood, where bacteria are not normally found. Some pathogens invade only the surface epithelium, skin or mucous membrane, but many travel more deeply, spreading through the tissues and disseminating by the lymphatic and blood streams. In some rare cases a pathogenic microbe can infect an entirely healthy person, but infection usually occurs only if the body's defence mechanisms are damaged by some local trauma or an underlying debilitating disease, such as wounding, intoxication, chilling, fatigue, and malnutrition. In many cases, it is important to differentiate infection and colonization, which is when the bacteria are causing little or no harm.
Most pathogenic bacteria can be grown in cultures and identified by Gram stain and other methods. Bacteria grown in this way are often tested to find which antibiotics will be an effective treatment for the infection. For hitherto unknown pathogens, Koch's postulates are the standard to establish a causative relationship between a microbe and a disease.
Diseases
Each species has specific effect and causes symptoms in people who are infected. Some people who are infected with a pathogenic bacteria do not have symptoms. Immunocompromised individuals are more susceptible to pathogenic bacteria.[7]
Pathogenic susceptibility
Some pathogenic bacteria cause disease under certain conditions, such as entry through the skin via a cut, through sexual activity or through compromised immune function.[citation needed]
Some species of Streptococcus and Staphylococcus are part of the normal skin microbiota and typically reside on healthy skin or in the nasopharyngeal region. Yet these species can potentially initiate skin infections. Streptococcal infections include sepsis, pneumonia, and meningitis.[8] These infections can become serious creating a systemic inflammatory response resulting in massive vasodilation, shock, and death.[9]
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.[14] The most frequent cause 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.[15][16]
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.
The symptoms of disease appear as pathogenic bacteria damage host tissues or interfere with their function. The bacteria can damage host cells directly or indirectly by provoking an immune response that inadvertently damages host cells,[21] or by releasing toxins.[22]
Direct
Once pathogens attach to host cells, they can cause direct damage as the pathogens use the host cell for nutrients and produce waste products.[23] For example, Streptococcus mutans, a component of dental plaque, metabolizes dietary sugar and produces acid as a waste product. The acid decalcifies the tooth surface to cause dental caries.[24]
Toxin production
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 worsen at first as the bacteria are killed and they release their endotoxins. Exotoxins are secreted into the surrounding medium or released when the bacteria die and the cell wall breaks apart.[25]
Indirect
An excessive or inappropriate immune response triggered by an infection may damage host cells.[1]
Survival in host
Nutrients
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.[25]
Bacterial pathogens also require access to carbon and energy sources for growth. To avoid competition with host cells for glucose which is the main energy source used by human cells, many pathogens including the respiratory pathogen Haemophilus influenzae specialise in using other carbon sources such as lactate that are abundant in the human body [26]
Identification
Typically identification is done by growing the organism in a wide range of cultures which can take up to 48 hours. The growth is then visually or genomically identified. The cultured organism is then subjected to various assays to observe reactions to help further identify species and strain.[27]
Treatment
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.[28] 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.[29]Phage therapy, using bacteriophages can also be used to treat certain bacterial infections.[30]
Prevention
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).[citation needed]
List of genera and microscopy features
Many genera contain pathogenic bacterial species. They often possess characteristics that help to classify and organize them into groups. The following is a partial listing.
List of species and clinical characteristics
Overall age-standardised mortality rate per 100 000 population for 33 pathogens investigated, 2019[3]
Global number of deaths (A) and YLLs (B), by pathogen and infectious syndrome, 2019[3]
Global number of deaths, by pathogen, age, and sex groups, 2019[3]
This is description of the more common genera and species presented with their clinical characteristics and treatments.
^ a bRyan, Kenneth J.; Ray, C. George; Ahmad, Nafees; Drew, W. Lawrence; Lagunoff, Michael; Pottinger, Paul; Reller, L. Barth; Sterling, Charles R. (2014). "Pathogenesis of Bacterial Infections". Sherris Medical Microbiology (6th ed.). New York: McGraw Hill Education. pp. 391–406. ISBN 978-0-07-181826-1.
^McFall-Ngai, Margaret (2007-01-11). "Adaptive Immunity: Care for the community". Nature. 445 (7124): 153. Bibcode:2007Natur.445..153M. doi:10.1038/445153a. ISSN 0028-0836. PMID 17215830. S2CID 9273396.
^ a b c d eIkuta, Kevin S.; Swetschinski, Lucien R.; Aguilar, Gisela Robles; Sharara, Fablina; Mestrovic, Tomislav; Gray, Authia P.; Weaver, Nicole Davis; Wool, Eve E.; et al. (21 November 2022). "Global mortality associated with 33 bacterial pathogens in 2019: a systematic analysis for the Global Burden of Disease Study 2019". The Lancet. 400 (10369): 2221–2248. doi:10.1016/S0140-6736(22)02185-7. ISSN 0140-6736. PMC 9763654. PMID 36423648.
^"Tuberculosis (TB)". www.who.int.
^ a b c dSantosham, 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. PMC 3747995. PMID 23976885.
^Hou, Chia-Yi (23 November 2022). "Bacterial infections linked to 1 in 8 deaths in 2019". The Hill. Retrieved 12 December 2022.
^Azoulay E, Russell L, Van de Louw A, Metaxa V, Bauer P, Povoa P, Montero JG, Loeches IM, Mehta S, Puxty K, Schellongowski P, Rello J, Mokart D, Lemiale V, Mirouse A (February 2020). "Diagnosis of severe respiratory infections in immunocompromised patients". Intensive Care Medicine. 46 (2): 298–314. doi:10.1007/s00134-019-05906-5. PMC 7080052. PMID 32034433.
^"Streptococcal Infections - Infectious Diseases". MSD Manual Professional Edition. Retrieved 2 May 2021.
^Fish DN (February 2002). "Optimal antimicrobial therapy for sepsis". Am J Health Syst Pharm. 59 (Suppl 1): S13–9. doi:10.1093/ajhp/59.suppl_1.S13. 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.
^Muzny CA, Schwebke JR (August 2016). "Pathogenesis of Bacterial Vaginosis: Discussion of Current Hypotheses". The Journal of Infectious Diseases. 214 (Suppl 1): S1–5. doi:10.1093/infdis/jiw121. PMC 4957507. PMID 27449868.
^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
^Greenwood, David; Barer, Mike; Slack, Richard; Irving, Will (2012). "Bacterial Pathogenicity". Medical Microbiology, a Guide to Microbial Infections: Pathogenesis, Immunity, Laboratory Investigation, and Control (18th ed.). Edinburgh: Churchill Livingstone. pp. 156–167. ISBN 9780702040894.
^Tortora, Gerald J.; Funke, Berdell R.; Case, Christine L. (2016). "Microbial Mechanisms of Pathogenicity". Microbiology, an Introduction (12th ed.). Pearson Education. pp. 417–438. ISBN 978-0-321-92915-0.
^Nash, Anthony A.; Dalziel, Robert G.; Fitzgerald, J. Ross (2015). "Mechanisms of Cell and Tissue Damage". Mims' Pathogenesis of Infectious Disease (6th ed.). London: Academic Press. pp. 171–231. ISBN 978-0-12-397188-3.
^ a bTortota, Gerard (2013). Microbiology an Introduction. Pearson. ISBN 978-0-321-73360-3.
^Hosmer, Jennifer; Nasreen, Marufa; Dhouib, Rabeb; Essilfie, Ama-Tawiah; Schirra, Horst Joachim; Henningham, Anna; Fantino, Emmanuelle; Sly, Peter; McEwan, Alastair G.; Kappler, Ulrike (2022-01-27). "Access to highly specialized growth substrates and production of epithelial immunomodulatory metabolites determine survival of Haemophilus influenzae in human airway epithelial cells". PLOS Pathogens. 18 (1): e1010209. doi:10.1371/journal.ppat.1010209. ISSN 1553-7374. PMC 8794153. PMID 35085362.
^Cassells AC (2012). "Pathogen and Biological Contamination Management in Plant Tissue Culture: Phytopathogens, Vitro Pathogens, and Vitro Pests". Plant Cell Culture Protocols. Methods in Molecular Biology. Vol. 877. pp. 57–80. doi:10.1007/978-1-61779-818-4_6. ISBN 978-1-61779-817-7. PMID 22610620.
^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: 238. doi:10.3389/fmicb.2012.00238. PMC 3400130. PMID 22833738.
^ a b c d e f g h i j k l m n o p q rUnless 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 978-0-7817-8215-9.
^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. doi:10.1128/JCM.26.12.2661-2663.1988. PMC 266968. PMID 2906642.
^ a b c d e f g h i j k l m n o p q r s t u v w x y z aa ab ac ad ae af ag ah ai aj ak al am an ao ap aq ar as at au av aw ax ay az ba bb bc bd be bf bg bh bi bj bk bl bm bn bo bp bq br bs bt bu bv bw bx by bz ca cb cc cd ce cf cg ch ci cj ck cl cm cn co cp cq cr cs ct cu cv cw cx cy cz da db dc dd de df dg dh di dj dk dl dm dn do dp dq dr ds dt du dv dw dx dy dz ea eb ec ed ee ef eg eh ei ej ek el em en eo ep eq er es et eu ev ew ex ey ez fa fb fc fd fe ff fg fh fi fj fk fl fm fn fo fp fq fr fs ft fu fv fw fx fy fz ga gb gc gd ge gf gg gh gi gj gk gl gm gn go gp gq gr gs gt gu gv gw gx gy gz ha hb hc hd he hf hg hh hi hj hk hl hm hn ho hp hq hr hs ht hu hv hw hx hy hz ia ib ic id ie if ig ih ii ij ik il im in io ip iq ir is it iu iv iw ix iy iz ja jb jc jd je jf jg jh ji jj jk jl jm jn jo jp jq jr js jt ju jv jw jx jy jz ka kb kc kd ke kf kg kh ki kj kk kl km kn ko kp kq krFisher, 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 978-0-7817-8215-9.
^ a b cEpps SV, Harvey RB, Hume ME, Phillips TD, Anderson RC, Nisbet DJ (2013). "Foodborne Campylobacter: infections, metabolism, pathogenesis and reservoirs". International Journal of Environmental Research and Public Health. 10 (12): 6292–304. doi:10.3390/ijerph10126292. PMC 3881114. PMID 24287853.
^ a bBowden GHW (1996). Baron S; et al. (eds.). Actinomycosis in: Baron's Medical Microbiology (4th ed.). Univ of Texas Medical Branch. ISBN 978-0-9631172-1-2. (via NCBI Bookshelf).
^Baron, Samuel (1996). Medical Microbiology (4th ed.). University of Texas Medical Branch at Galveston, Galveston, Texas. ISBN 978-0-9631172-1-2.
^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. Archived from the original on April 26, 2015. Retrieved May 3, 2015.
^Gunn BA (1984). "Chocolate agar, a differential medium for gram-positive cocci". Journal of Clinical Microbiology. 20 (4): 822–3. doi:10.1128/JCM.20.4.822-823.1984. PMC 271442. PMID 6490866.
^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. S2CID 24668819.
^Johnson RC, Harris VG (1967). "Differentiation of Pathogenic and Saprophytic Leptospires I. Growth at Low Temperatures". J. Bacteriol. 94 (1): 27–31. doi:10.1128/JB.94.1.27-31.1967. 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. Archived from the original on 2015-05-07. Created: 30 September 2005. Last update: 01 April 2013
^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. S2CID 6685738.
^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. S2CID 34004290.
^ a b c d e f g h i j k l m n o p q r s t u v w x y z aa ab ac ad ae af ag ah ai aj ak al am an ao ap aq ar as at au av aw ax ay az ba bb bc bd be bf bg bh bi bj bk bl bm bn bo bp bq br bs bt bu bv bw bx by bz ca cb cc cd ce cf cg ch ci cj ck cl cm cn co cp cq cr cs ct cu cv cw cx cy cz da db dc dd de df dg dh di dj dk dl dm dn do dp dq dr ds dt du dv dw dx dy dz ea eb ec ed ee ef eg eh ei ej ek el em en eo ep eq er es et eu ev ew ex ey ez fa fb fc fd fe ff fg fh fi fj fk fl fm fn fo fp fq fr fs ft fu fv fw fx fy fz ga gb gc gd ge gf gg gh gi gj gk gl gm gn go gp gq gr gs gt gu gv gw gx gy gz ha hb hc hd he hf hg"Bacteria Table" (PDF). Creighton University School of Medicine. Archived from the original (PDF) on 2015-05-01. Retrieved 2015-05-03.
^Brook, I (Oct 2008). "Actinomycosis: diagnosis and management". Southern Medical Journal. 101 (10): 1019–23. doi:10.1097/SMJ.0b013e3181864c1f. PMID 18791528. S2CID 19554893.
^Shapiro ED (2014). "Clinical practice. Lyme disease". The New England Journal of Medicine. 370 (18): 1724–31. doi:10.1056/NEJMcp1314325. PMC 4487875. PMID 24785207.
^ a bSanchez JL (2015). "Clinical Manifestations and Treatment of Lyme Disease". Clinics in Laboratory Medicine. 35 (4): 765–78. doi:10.1016/j.cll.2015.08.004. PMID 26593256.
^Halperin JJ (2015). "Nervous System Lyme Disease". Clinics in Laboratory Medicine. 35 (4): 779–95. doi:10.1016/j.cll.2015.07.002. PMID 26593257.
^ a b c d e fBarbour, Alan G. (2017). "Relapsing Fever". In Kasper, Dennis L.; Fauci, Anthony S. (eds.). Harrison's Infectious Diseases (3rd ed.). New York: McGraw Hill Education. pp. 678–687. ISBN 978-1-259-83597-1.
^Cutler SJ (2015). "Relapsing Fever Borreliae: A Global Review". Clinics in Laboratory Medicine. 35 (4): 847–65. doi:10.1016/j.cll.2015.07.001. PMID 26593261.
^Atkinson, William (May 2012). Tetanus Epidemiology and Prevention of Vaccine-Preventable Diseases (12 ed.). Public Health Foundation. pp. 291–300. ISBN 9780983263135. Archived from the original on 13 February 2015. Retrieved 12 February 2015.
^"Diphtheria vaccine" (PDF). Wkly Epidemiol Rec. 81 (3): 24–32. 20 January 2006. PMID 16671240. Archived (PDF) from the original on 6 June 2015.
^"Klebsiella pneumoniae in Healthcare Settings". Centers for Disease Control and Prevention. 19 February 2021. Page last reviewed: November 24, 2010. Page last updated: August 27, 2012
^Slack, A (Jul 2010). "Leptospirosis". Australian Family Physician. 39 (7): 495–8. PMID 20628664.
^McBride, AJ; Athanazio, DA; Reis, MG; Ko, AI (Oct 2005). "Leptospirosis". Current Opinion in Infectious Diseases. 18 (5): 376–86. doi:10.1097/01.qco.0000178824.05715.2c. PMID 16148523. S2CID 220576544.
^ a bHartskeerl, Rudy A.; Wagenaar, Jiri F.P. (2017). "Leptospirosis". In Kasper, Dennis L.; Fauci, Anthony S. (eds.). Harrison's Infectious Diseases. New York: McGraw Hill Education. pp. 672–678. ISBN 978-1-259-83597-1.
^"Leprosy Fact sheet N°101". World Health Organization. January 2014. Archived from the original on 2013-12-12.
^"Tuberculosis Fact sheet N°104". WHO. October 2015. Archived from the original on 23 August 2012. Retrieved 11 February 2016.
^Institut Pasteur Press Office - Vaccine against shigellosis (bacillary dysentery):a promising clinical trial Archived 2009-02-25 at the Wayback Machine 15 January 2009. Retrieved on 27 February 2009
^Levinson, W. (2010). Review of Medical Microbiology and Immunology (11th ed.). pp. 94–9.
^"Syphilis - CDC Fact Sheet (Detailed)". CDC. 2 November 2015. Archived from the original on 6 February 2016. Retrieved 3 February 2016.
^Kent ME, Romanelli F (February 2008). "Reexamining syphilis: an update on epidemiology, clinical manifestations, and management". Annals of Pharmacotherapy. 42 (2): 226–36. doi:10.1345/aph.1K086. PMID 18212261. S2CID 23899851.
^Zhou D, Han Y, Yang R (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.
^Kilonzo BS, Makundi RH, Mbise TJ (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.
^ a bBernstein H, Bernstein C, Michod RE (2018). Sex in microbial pathogens. Infection, Genetics and Evolution volume 57, pages 8-25. https://doi.org/10.1016/j.meegid.2017.10.024
External links
Bacterial Pathogen Pronunciation by Neal R. Chamberlain, Ph.D. at A.T. Still University
Pathogenic bacteria genomes and related information at PATRIC, a Bioinformatics Resource Center funded by NIAID