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About the Microbe
About the Microbe
The bacteria Cronobacter sakazakii is a foodborne pathogen that causes sepsis, necrotizing enterocolitis, and meningitis in newborns. *
People care about this bacteria because it causes severe illness in newborns, immunocompromised individuals, and older people. These illnesses can lead to death in some cases. *
The CDC states that infection by Cronobacter sakazakii must be treated immediately by antibiotics. *
Cronobacter sakazakii is traditionally found in dry environments. It is most commonly detected in dry foods such as baby powder and starch. It can also be found in sewer water. *
Taxonomy
Taxonomy
Taxonomy of Cronobacter sakazakii *
Domain: Bacteria
Phylum: Proteobacteria
Class: Gammaproteobacteria
Order: Enterobacterales
Family: Enterobacteriaceae
Genus: Cronobacter
Species: Cronobacter sakazakii
Visualizing the Microbe
Visualizing the Microbe
Cronobacter sakazakii is a gram negative bacteria. This means that it does not retain the crystal violet dye used in gram staining. The bacteria shows up as a red or pink color after it has been stained which tells us that it is not gram positive and is instead gram negative.
Cronobacter sakazakii has a straight rod shape and is therefore classified as bacillus, they can also be seen as individual rods or in groups.
This image of a Cronobacter sakazakii gram stain was presumably taken with a Transmission Electron Microscope, however; no indication of what type of microscope was given from the source. See Figure 1.
Figure 1. Cronobacter sakazakii gram stain under a Transmission Electron Microscope.
Diagnostic Tests
Diagnostic Tests
Cronobacter sakazakii most predominately can be identified by its results of the following tests:
Blood Agar - Shows growth indicating gamma hemolysis is occurring. See Figure 2.
MacConkey Agar - Shows growth of colored colonies indicating that this microbe ferments lactose and therefore creates an acidic environment. See Figure 3.
Mannitol Salt Agar - D-Mannitol positive result indicates that this microbe can tolerate high concentrations of salt. See Figure 4.
16s primers can be used to take other diagnostic tests. In this case the primers used were:
acgctggcgg caggcctaac acatgcaagt cgaacggtaa cagggagcag cttgctgctc
tgctgacgag tggcggacgg gtgagtaatg tctgggaaac tgcctgatgg agggggataa
The calculated melting temperature, using these primers, is 87.2°C in basic conditions and 100.9°C in salt. (NOTE: Some error may have occurred when copying the listed primers into the testing program.)
Using the same program and primers used to calculate the melting temperature, the GC content was calculated to be 55%.
The results of an In silico PCR test can be seen in Figure 5.
Figure 2. Cronobacter sakazakii after being plated on a Blood Agar plate.
Figure 5. Results of an In silico PCR test using the primers mentioned under the "Diagnostic Tests" section.
Figure 3. Cronobacter sakazakii after being plated on a MacConkey Agar plate.
Figure 4. Cronobacter sakazakii after being plated on a Mannitol Salt Agar plate.
Disease and Treatment
Disease and Treatment
This bacteria causes necrotizing enterocolitis, bacteremia, and meningitis in infants and neonates as well as the immunocompromised and elderly. Infections have a 40-80% mortality rate. *
General antibiotics are used to treat infections by Cronobacter sakazakii. Their is currently a rise in antibiotic resistance within strains of Cronobacter sakazakii. Determining this early has given scientists a higher drive to discover alternative treatments for this bacteria. *
References
References
1.
Cronobacter sakazakii.
2.
Culture-31-1.pdf.
3.
Cronobacter sakazakii (Farmer et al.) Iversen et al. ATCC ® 29544&.
4.
Cronobacter Sakazakii - an overview | ScienceDirect Topics.
5.
Cronobacter sakazakii.
6.
2020. Testing and Treatment | Cronobacter | CDC.
7.
2018. Home | Cronobacter | CDC.
8.
Tankeshwar A. 2013. Mannitol Salt Agar (MSA): Composition, uses and colony characteristics. Learn Microbiology Online.
9.
Parra-Flores J, Aguirre J, Juneja V, Jackson EE, Cruz-Córdova A, Silva-Sanchez J, Forsythe S. 2018. Virulence and Antibiotic Resistance Profiles of Cronobacter sakazakii and Enterobacter spp. Involved in the Diarrheic Hemorrhagic Outbreak in Mexico. Front Microbiol 9.
10.
Fei P, Jiang Y, Feng J, Forsythe SJ, Li R, Zhou Y, Man C. 2017. Antibiotic and Desiccation Resistance of Cronobacter sakazakii and C. malonaticus Isolates from Powdered Infant Formula and Processing Environments. Front Microbiol 8.
11.
Farmer JJ, Davis BR, Hickman-Brenner FW, McWhorter A, Huntley-Carter GP, Asbury MA, Riddle C, Wathen-Grady HG, Elias C, Fanning GR. 1985. Biochemical identification of new species and biogroups of Enterobacteriaceae isolated from clinical specimens. J Clin Microbiol 21:46–76.
12.
Farmer JJ, Asbury MA, Brenner DJ. Enterobacter sakazakii:A New Species of “Enterobacteriaceae”Isolated from Clinical Specimens 16.
About the Researcher
About the Researcher
Matthew Hauerwas is a Junior at the University of Florida. He transferred there as a Microbiology and Cell Science Major in his Sophomore year of university after spending one year at Florida State University. His passion for microbiology began the summer before his Senior year of high school when he took a summer course on microbiology, at this time, his mother was also infected by MRSA after receiving surgery to remove a breast cancer tumor. An interesting fact about Matthew is that he earned the rank of Eagle Scout from the Boy Scouts of America in his home state of Kansas when he was 15 years old.
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