And can I get a hot tub?

Have you ever been curious as to what bacteria lurk in the warm waters of your hot tub? Well if not properly taken care of, there are quite a few that can cause you harm. For example, Mycoplasma, Legionella, and Pseudomonas are all bacteria that love to grow in a hot tub environment. Since this week we have learned about lower respiratory tract diseases, Legionella is a disease that not many people are aware of, and that’s why I have chosen to give you the 4-1-1 on this disease.

The bacteria got its name in 1976, when many people who went to a Philadelphia convention of the American Legion suffered from an outbreak of this disease, a type of pneumonia (lung infection). Although this type of bacteria was around before then, more illness from Legionnaires' disease is being detected now. Legionnaires' disease can have symptoms like many other forms of pneumonia, so it can be hard to diagnose at first. Signs of the disease can include: a high fever, chills, and a cough. Some people may also suffer from muscle aches and headaches. These symptoms usually begin 2 to 10 days after being exposed to the bacteria. A milder infection caused by the same type of Legionella bacteria is called Pontiac Fever. The symptoms of Pontiac Fever usually last for 2 to 5 days and may also include fever, headaches, and muscle aches; however, there is no pneumonia. Symptoms go away on their own without treatment and without causing further problems.

People get Legionnaires' disease when they breathe in a mist or vapor (small droplets of water in the air) that has been contaminated with the bacteria. One example might be from breathing in the steam from a hot tub that has not been properly cleaned and disinfected. 

Who is at risk for this disease? People at risk of getting sick from the bacteria are elderly people, as well as people who are current or former smokers, or those who have a chronic lung disease. People who have weak immune systems from diseases like cancer, diabetes, or kidney failure are also more likely to get sick from Legionella bacteria. People who take drugs to suppress (weaken) the immune system (like after a transplant operation or chemotherapy) are also at higher risk.

The laboratory criteria according to the CDC are:

• The isolation of Legionella from respiratory secretions, lung tissue, pleural fluid, or other normally sterile fluids, or 
• Demonstration of a fourfold or greater rise in the reciprocal immunofluorescence antibody (IFA) titer to greater than or equal to 128 against Legionella pneumophila serogroup 1 between paired acute- and convalescent-phase serum specimens, or   
• Detection of L. pneumophila serogroup 1 in respiratory secretions, lung tissue, or pleural fluid by direct fluorescent antibody testing, or   
• Demonstration of L. pneumophila serogroup 1 antigens in urine by enzyme-linked immunosorbent assay, etc.

I hope you have all learned a little more about Legionnaire's Disease!


Check out this House Spoof about Legionnaire's Disease!

Got Strep Throat???

Is it sore throat season already? Well, sore throats can occur year round. The primary cause of a sore throat, or pharyngitis, is a bacterium known as Streptococcus pyogenes. The primary infection of Streptococcus pyogenes is a strep throat or tonsillitis. A painful, red throat with white patches on your tonsils is characteristic of pharyngitis, otherwise known as strep throat.  It is usually accompanied by swollen lymph nodes, fever, and headache.  Occasionally nausea, vomiting, and abdominal pain also accompany it. The suppurative sequelae of the initial infection are sinusitis or otitis media. Other nonsuppurative sequelae of S. pyogenes are scarlet fever. The frequency of Streptococcus pyogenes for the general population is 15-35%. Streptococcus pyogenes is classified as Group A streptococcus. Group A streptococci typically have a capsule composed of hyaluronic acid and are beta-hemolytic, which is characteristic for Streptococcus pyogenes. Beta-hemolytic streptococci produce a toxin that forms a clear zone of hemolysis on blood agar, demonstrating its ability to destroy red blood cells.  This hemolysis is attributed to toxins formed by Group A streptococci called streptolysins.  Streptolysins can destroy not only red blood cells, but also the white blood cells responsible for fighting off bacteria and disease, as well as other body cells.

The identification of Streptococcus pyogenes is to make a presumptive decision based on the gram stain and colony morphology. After, a PYR test can easily be performed. If the test is positive, it can be presumptively identified as Streptococcus pyogenes. Further tests such as a Bacitracin disk are performed where the expected results are to be sensitive to the organism. A quick test that can be performed in a clinic setting rather than the clinical laboratory is the Quick Vue Dipstick Strep A Test. It is a rapid lateral-flow immunoassay where the extracted antigen attaches to the antibody to the step A colored particles. The complex then migrates through the membrane and attaches the antibody to the strep A where the test line will produce a pink to purple color. On the control line, the complex reacts with the antibody, or protein A, to produce a blue color. To report a positive test, it must be reported as “Positive for Group A Streptococcus antigen.” To report a negative test, it must be reported as “Negative for Group A Streptococcus antigen.” For an invalid report, it must be reported as “Invalid Group A Streptococcus antigen test result. Possible interfering substance present. Please submit another sample if clinically indicated.” The advantages to this assay are that it has good specificity where the patient can be treated sooner, and it is faster than a culture. The disadvantages to this assay are that it has lower sensitivity than a culture and it does not detect other infections due to other groups of streptococci.

According to a CDC report dated April 3, 2008, approximately 9,000-11,500 cases of invasive GAS disease (3.2-3.9 per 100,000 population) occur each year in the United States. More than 10 million noninvasive GAS infections (primarily throat and superficial skin infections) occur annually. The best way to avoid strep throat is to avoid close contact with someone who is already infected with strep. It may also be helpful to reduce stress, get plenty of rest, and fortify your body's natural defenses. Frequent hand washing can help prevent infection as well.

Found a pretty tough quiz that include some questions from my blog but also from our respiratory tract infection lectures. Check it out!!!

Respiratory Infection Quiz!

Cat Scratch Fever

How many people have a household cat as a pet? Yes, I am referring to that cute little kitty that is all curled up next to you. They might look friendly at first, but then something “rubs” them the wrong way. Next thing you know you’re grabbing your arm and screaming, “Ouch!” There is now a slight scratch that is throbbing with pain. A quick clean up and a band-aid is all the normal human being does to solve the problem. Little do you know, there could be a much more severe consequence.

Cat-scratch fever, or cat-scratch disease, is caused by Bartonella henselae, which is a normal flora of the cat’s saliva. B. henselae is also associated with bacteremia and endocarditis. Symptoms usually do not show for a few days following the incident. Once the symptoms start, however, they can last for a couple weeks. Symptoms of cat scratch fever include pain and swelling of the lymph nodes, general discomfort and body aches, and loss of appetite. Many times, cat scratch fever is never diagnosed. The symptoms are sometimes mild and not severe enough to warrant treatment. Cat scratch fever is not a very common disease. According to the U.S. Centers for Disease Control and Prevention, there are about 25,000 cases in the United States each year. However, there are likely many more cases that go undiagnosed or unreported.

In order to isolate this organism, the Isolator system is used for blood culture. It is plated out to fresh chocolate or 5% blood agar (rabbit or horse). The plates should be incubated at 35⁰C in CO₂ for up to 30 days. Bartonella henselae is a weak staining, gram-negative rod that stains better with a Gimenez. It appears irregular in shape, raised, whitish, and rough (cauliflower) like. The organism is catalase and oxidase negative as well as negative for all carbohydrates. The presumptive identification is based on colony growth after seven days with characteristic colony morphology, wet prep, catalase, and oxidase reactions. 

I hope everyone has learned a little more about what to expect from the adorable kitty curled up by your side. Just remember for next time that if you get a scratch that does not appear normal, you might want to see your doctor for a possible infection of Bartonella henselae.

 Check out this song!!!

 

A little about me :)

Hey everyone! My name is Destiny and I am a graduate student in the Clinical Laboratory Sciences program at the University of Alabama at Birmingham (UAB). I have an undergraduate Bachelor's of Science degree in Physical Sciences/Chemistry from Auburn Montgomery (AUM). I am originally from Swansea, IL and moved to Montgomery, AL to attend AUM on a basketball scholarship. After finishing my basketball career and graduating, I applied for the CLS program, was accepted, and moved to Birmingham. I will be graduating this August and looking forward to starting my career as a Medical Technologist. This summer I am taking a course titled Infectious Diseases.  Every week I will be writing a blog about something interesting I learn about. Please log on every week to read a new blog entry on my exciting laboratory studies!