A monthly newsletter from the office of Dr Mary Kirk
June 2016
Listeria

During the past two years the Listeria bacteria has garnered a great amount of press due to the recall of Blue Bell Ice Cream in 2015 and last month's mass recall of frozen veggies circulated by CRF Frozen Foods.
 
Although food recalls may seem sudden, they tend to be the culmination of years' worth of surveillance. Public health officials map illnesses across the country and watch carefully for patterns in bacterial agents, food sources, distributing companies, and other data. In most cases, pinpointing an exact moment of contamination is very difficult.

May's recall of frozen vegetables was due to an eight person pattern of infection over the last three years with a likely link to a single distributer.1

Scientists first realized that Listeria was linked to food intake in 1981 when an outbreak in Canada was linked to cabbage consumption. Since, other outbreaks have been linked to milk, uncooked soft cheeses, and ready-to-eat meats.2




Listeria is a fairly common bacteria that rarely causes serious infection in humans unless there are preexisting medical conditions. However, it has been known to have devastating effects on pregnancy. Also, during pregnancy a part of the woman's immune system is suppressed to prevent rejection of the baby which also causes an increase in her susceptibility to this infection. 3 A pregnant woman who has acquired the infection is not generally in any mortal danger herself, but Listeria infections in babies are often severe and can be fatal.

Based on the results of a collaborative study between Stanford University Medical Center and the University of California Berkeley, scientists determined that the placenta does a noteworthy job of protecting the infant from Listeria acquired by the mother, but that if even one bacteria manages to break through its barriers, the placenta then becomes a significant hub for infection.4 In this situation, complications such as preterm labor, miscarriage, stillbirth, or infection of a newborn during the birthing process have been known to occur.

Due to this, physicians recommend that a pregnant woman abstain from raw or undercooked meats completely and only consume pasteurized dairy products. In the past, the FDA advised avoiding all soft cheeses, but has fairly recently changed its position to only recommend abstinence from cheeses made from raw/unpasteurized milk.5 Although ready-to-eat meats have been known to carry Listeria, the risk is extremely low as long as they are properly heated. Patients are generally advised to avoid them only if outbreaks become a problem in their area. A gestating mother needs a varied nutrient-rich diet to sustain a pregnancy. Avoiding too many food items is far riskier than the chance of infection.

If infection is known to occur, your physician can prescribe antibiotics to protect your baby. However, it is best to follow the guidelines listed above to limit the risk of exposure as no symptoms may arise despite the infection being present.

To help reduce the risk in all individuals the FDA and CDC have recommended the following:

"All produce should be rinsed before consumption even if it will be peeled. A scrub brush should be used on all firm items, like melons and gourds. These should then be dried with a clean cloth or paper towel. Also, uncooked meats should be kept apart from veggies to prevent the transmission of bacteria during preparation. Always wash your hands before and after food preparation and clean countertops and utensils after use. Freezer temperatures should at or below 0°F (≈-17°C) and refrigerator temperatures at or below 40°F (≈4°C)."

The following links provide more information and the latest updates to the FDA and CDC's guidelines:









1. "Multistate Outbreak of Listeriosis Linked to Frozen Vegetables." Centers for Disease Control and Prevention.
Centers for Disease Control and Prevention, 03 May 2016. Web. 19 May 2016. <http://www.cdc.gov/listeria/outbreaks/frozen-vegetables-05-16/index.html>.


2. Varma JK, et al. "Listeria Monocytogenes Infection from Foods Prepared in a Commercial Establishment: A Case-Control Study of Potential Sources of Sporadic Illness in the United States." Clinical Infectious Diseases : An Official Publication of the Infectious Diseases Society of America 44.4 (2007): 521-8. Print.

3. Bubonja-Sonje, Marina, et al. "Listeriosis in Pregnancy: Case Report and Retrospective Study." Journal of Maternal-Fetal and Neonatal Medicine 26.3 (2013): 321-323. Web.


4. Bakardjiev AI, Theriot JA, and Portnoy DA. "Listeria Monocytogenes Traffics from Maternal Organs to the Placenta and Back." PLoS Pathogens 2.6 (2006): E66. Print.

5. "Prevention." Centers for Disease Control and Prevention. Centers for Disease Control and Prevention, 20 Nov. 2014. Web. 24 May 2016. <http://www.cdc.gov/listeria/prevention.html>.


Bone Health

Bones are amazing examples of structural engineering. They are the framework around which our bodies are built, allowing us to be the active and enduring beings that we are. Bone manages to be both lightweight and extremely tough, as well as self-repairing and adaptive! 

Below their smooth hard surface is a honeycomb web of spongy bone. This web-like structure is largely what enables it to be so light yet take so much stress. Some modern buildings, such as China's Beijing National Stadium (shown above), are modeled similarly due to this design's resilience.
 
Bone health is important for more than just hearty framework. Many processes, including blood cell production, occur inside the bones! As a human ages, these processes become less efficient and the internal spongy bone's honeycomb structure becomes thinner or less dense, making it more fragile.


Spongy bone samples from a 21 year old (a) and a 65 year old (b)

Once this loss has become significant it is classified as osteoporosis. It has been determined that 50% of women and 25% of men will suffer from an osteoporosis-related fracture after the age of 50. 1 Researchers are continuously looking into the causes and effects of aging on the bone structure to better understand how to prevent bone loss and fracture. 

Studies have shown calcium intake and weight bearing activity to be expressly important factors in bone loss prevention.2 A 4 year study conducted at the University of Arizona found that, on average, postmenopausal women following an exercise and calcium regimen, not only didn't lose bone density, but increased it by 1-2%! 3

Certain exercises are particularly helpful for targeting areas vulnerable to fracture. These include leg presses, one-arm military presses, seated rowing, wall squats and Smith squats, back extensions, and lateral pull downs. However, just avoiding sedentariness in general can make a big difference!

The amount of calcium supplementation needed depends on age and gender. A useful information sheet for calcium intake is available on our website under the resources tab or just use the following link:  Calcium Sheet

The body will only absorb about 500 mg of calcium at a time, so doses must be broken up throughout the day for optimum absorption. It is also important to remember that the body needs Vitamin D to be able to utilize calcium. An additional supplement of Vitamin D is generally necessary. About 1000 IU of Vitamin D a day is an appropriate amount for most women.


1. Ritchie, Robert O., Markus J. Buehler, and Paul Hansma. "Plasticity and Toughness in Bone."
Physics Today 62.6 (2009). Print.

2. Tussing, Lisa, and Karen Chapman-Novakofski. "Osteoporosis Prevention Education: Behavior Theories and Calcium Intake." American Dietetic Association. Journal of the American Dietetic Association 105.1 (2005): 92-97. Print.

3. "Osteoporosis; Weight-Bearing Regimen, Calcium Citrate Proven to Increase Bone Mineral Density." Obesity, Fitness & Wellness Week (2006): 1350. Print.

Fun Fact:

At birth the human body contains 270 separate bones. A number of these bones will fuse together as the infant matures, resulting in a final bone count of 206!
 

The stapes is the smallest bone in the body. It resides in the middle ear, is about 3mm in size, and shaped like a saddle stirrup.

Dr Mary C Kirk | 918-508-2200 | www.kirkobgyn.com