User:Periwinklemoose11/sandbox

=Introduction= Urinary tract infections (UTI's) are caused by colonization of bacteria in the urethra, often by pathogenic Escherichia coli. UTI's are more common in women, as they have a shorter urethra. Symptoms include bloody urine, painful urination, and straining to urinate regardless of an empty bladder. UTI's can be diagnosed with a rapid test and are treated with antibiotics and hydration. Risk groups include young, sexually active women and menopausal women.

Premise
The human body hosts billions of commensal bacteria that may fend off pathogens, aid digestion, metabolize polymers, and keep mucosal surfaces clean. The microflora are affected by diet, hygiene, activities, and drugs. Many sexually active young women take hormonal contraceptives, which may have an influence on the gut microflora including pathogenic E. coli and their gene expression.

Few E. coli are pathogenic as commonly thought; they are found in the intestines of warm-blooded animals such as cows, pigs, birds, and more. Pathogenic strains have certain traits, or virulence factors that help them invade and colonize the host, such as pili, exotoxins, and formation of biofilms. E. coli can be grouped into 8 phylogroups: A, B1, B2, C, D, E, F, and K. Pathogenicity is most commonly associated with strains B2 and D, but presence of either strain does not indicate disease and vice versa.

=Materials and Methods= Fecal samples were obtained from 20 women between 18 and 23 with the intent of obtaining 30 isolates from each. 10 women used hormonal contraceptives, and 10 did not. They also submitted a survey about their diet, exercise, and sexual activity. Samples must be stored in the fridge if not immediately submitted and were processed less than 24 hours after taken.

Processing and Plating
Each fecal sample was homogenized in a fume hood before making serial dilutions. 1 g was weighed out in a falcon tube with 9 mL sterile deionized water. 10-2, 10-3, 10-4, 10-5, and 10-6 dilutions were made in 1 mL Eppendorf tubes. 100 &mu;L of dilutions 10-3, 10-4, 10-5, and 10-6 were plated onto MacConkey agar with glass beads in duplicate. All 8 plates were incubated at 37&deg; for 24 hours.

Calculate the colony forming units per mL (cfu/mL) with the following equation: "$ \frac {colonies} {volume plated} \times \frac {1} {dilution factor} $"

Streak for isolation of 33 colonies onto thirds of MacConkey agar. Incubate all 11 plates 37&deg; for 24 hours.



Nothing Gold Can Stay

By Robert Frost

Nature's first green is gold Her hardest hue to hold Her early leaf's a flower But only so an hour

As leaf subsides to leaf So Eden sank to grief As dawn turns down to day Nothing gold can stay.