Kerissa DeBoer
MICROL 231
11/6/18
Enterobacteriaceae Family Summary
Enterobacteriaceae are described as being a large family that is Gram negative and belongs to the domain bacteria. Enterobacteriaceae includes many harmless symbionts but has mostly different family pathogens: Escherichia coli, Salmonella, Shigella, and Yersinia pestis. This summary will cover these four different types of bacteria from the family and have an overview of their characteristics. Enterobacteriaceae are rod shaped and usually 1-5 micrometers in length. (1) On blood agar plates they appear as medium to large sized gray colonies. Common characteristics include being facultative anaerobes, fermenting sugars to produce lactic acid, and most reduce nitrate to nitrite. Enterobacteriaceae mostly use flagella to move around, but some are nonmotile. They are also not spore-forming and catalase reactions vary among them. (1)
Escherichia coli, otherwise known as E. coli, are found in the environment, foods, and intestines of people and animals. It is most commonly found in the lower intestine of endotherms and expelled into the environment within fecal matter. It is the most prevalent infecting organism in the Enterobacteriaceae family. (2) Most strains of E. coli are harmless, but others can make you very sick. Some kinds can cause diarrhea, but others can cause urinary tract infections, respiratory illness, and even pneumonia. (2) E. coli is referred to as the most-studied free-living organism. Over 700 different types of E. coli have been identified, but E. coli O157 is the most common type. (3) This type of bacteria can be cultured and grown easily in a lab setting and has been investigated for over 60 years.
Salmonella is a common bacterial disease that affects the intestinal tract. It is categorized into two different species: Salmonella enterica and Salmonella bongori. S. enterica is the type species and is divided into six subspecies that include over 2,600 serotypes. Salmonella species are predominantly motile with cell diameters between 0.7 and 1.5 micrometers. (4) Flagella also surrounds the outside of the cell body. Causes of infection within people are caused by infected food that is consumed. Raw meat, poultry, seafood, and eggs are some contaminated foods that could cause one to be infected with Salmonella and become sick. Typically, people that become infected with salmonella show no symptoms. On rare occasions, others develop diarrhea, fever, and abdominal cramps within 8-72 hours. Normally healthy people recover within a few days without treatment. (5)
Shigellosis is an infectious disease caused by a bacterial group called Shigella. This disease is found in primates, but not in other mammals. Naturally, it is only found in humans and gorillas. If one is infected by shigella, it usually causes dysentery to develop. Shigella is one of the leading bacterial causes of diarrhea in the world and causes between 74,000 and 600,000 deaths per year. (6) Shigella infection is typically obtained by ingestion. Fewer than 100 bacterial cells can be enough to cause a serious infection. (7) The most common symptoms are fever, nausea, vomiting, diarrhea, and stomach cramps. It is also known to cause large and painful bowel movements. Symptoms can take as long as a week to appear, but usually begin two to four days after ingestion. Shigella is implicated as one of the pathogenic causes of reactive arthritis around the world. Shigella is also known to be closely related to another Enterobacteriaceae family, E. coli. (7)
The last species that is part of the Enterobacteriaceae family is Yersinia pestis. Y. pestis is a nonmotile and stick shaped bacterium with bipolar staining. It tests negative for urease, lactose fermentation, and indole. Y. pestis is a facultative anaerobic organism that is known to affect humans via the oriental rat flea. This particular bacterium is known to cause the disease plague, which has three different forms: pneumonic, septicemic, and bubonic. (8) All three types were responsible for several high mortality epidemics throughout history. In particularly septicemic and pneumonic plague, there are no obvious signs that indicate that someone has been infected with Y. pestis and has the plague. Diagnosis is made by taking samples from the patient and submitting them for lab testing. Appropriate treatment would begin immediately to treat the illness.
In conclusion, Enterobacteriaceae are described as being a large family that is Gram negative and belongs to the domain bacteria. There are many harmless symbionts but mostly contains a few different family pathogens: Escherichia coli, Salmonella, Shigella, and Yersinia pestis. (1) Enterobacteriaceae are rod shaped, non-spore forming, and measure at 1-5 micrometers in length. (1) Most use flagella to move around, but a few species are nonmotile. Members of this family are normal members of the gut microbiota in humans and other animals, while some are found in water and soil. Enterobacteriaceae is a bacterium domain that consists of various different species that can be commonly found and treated in the todays world of medicine.
References
1) Brenner DJ; Krieg NR; Staley JT. 2005. The Gammaproteobacteria. Bergey's Manual of Systematic Bacteriology. 2B (2nd ed.).
2) Clark M. 2018. E. coli Food Poisoning, What is E. coli and how does it cause food poisoning?, in press.
3) Singleton P. 1999. Bacteria in Biology, Biotechnology and Medicine (5th ed.). Wiley. pp. 444–454. ISBN 978-0-471-98880-9.
4) Su LH.; Chiu CH. 2007. "Salmonella: clinical importance and evolution of nomenclature". Chang Gung Medical Journal. (3): 210–9.
5) Ryan KJ.; Ray CG. eds. 2004. Sherris Medical Microbiology (4th ed.). McGraw Hill. pp. 362–8.
6) Bowen A. 2016. "Chapter 3: Infectious Diseases Related to Travel". The Yellow Book: Health Information for International Travel.
7) Levinson W.E. 2006. Review of Medical Microbiology and Immunology (9th ed.). McGraw-Hill Medical Publishing Division. p. 30.
8) Ryan KJ.; Ray CG.; 2004. Sherris Medical Microbiology (4th ed.). McGraw Hill. pp. 484–488.
9) Carter A. 2014. "Black Death mysteries unlocked by McMaster scientists"