Susceptible To Group B Strep Infection example essay topic

Streptococci In a healthy human, the internal tissues such as blood, brain, and muscle are generally free of microorganisms. On the other hand, the surface tissues, such as skin, all of the mucous membrane in the mouth, nasal cavity and intestinal tract can easily and readily become available for microorganism to colonize and grow. Depending on the location in the human body, different bacteria choose to grow on a specific location that provides the nutrition it needs, with optimum condition such as pH. There are many different bacteria that collectively are called normal flora, and live in the human body. Many of these bacteria are commensal ly living in humans, and some others are symbiotic. Commensal bacteria only obtain their food from the human, and do not harm or benefit the host, on the other hand not only get their food from the host, but in return they also become beneficial to the host in providing nutrition that human can not make, such as vitamin K. One of the most recognized and extensively studied bacteria that often get more attention during the winter is Streptococcus.

There are different strains of strep. Depending on their ability of hemolysis of blood agar, strep can be subdivided into a, b and g (1-pp 143). There are many different laboratory tests that can be done to distinguish one strep from the other. Different treatments also have been developed to fight each strain of strep. The streptococci are a group of bacteria that infect human as well as animals. A very basic test to recognize strep is to perform blood agar plate (BAP) test.

Hemolysis of the blood agar can indicate the presence of strep bacteria. Most strep bacteria are either a or b on sheep blood agar. a- strep partially lyses the red blood cells, creating a greenish zone around each colony, whereas, complete lyses of blood by b- strep create a clear zone. g- does not lyse red blood cells, and no change or zone is created (1-pp 143). Streptococci are gram positive and exhibit purple color cocci when gram stained and observed under the microscope. Gram-positive bacteria such as streptococci have a membrane that contains a thick layer of. Peptidoglycan can retain the violet blue, and does not wash off with alcohol.

It grows in short chains, containing several streptococci. It looks a lot like a string of beads. Blood agar test show that Streptococcus such as groups A, B, C, F and G are b-, S. pneumonia e, a group D, which is also called Enterococcus, are a-. Among all groups of Streptococci, group A and B are the most common and disease causing in human. The most common form of Streptococcus is group A strep. Group A Streptococcus has a group-specific polysaccharide antigen ("C" substance) with a type-specific protein antigen ("M" protein) (2-pp 63).

It is also called S. pyogenes. As its name indicates, it is a pus forming bacteria. Pus is formed when the bacteria lyses the red blood cells, and this process results in a thick yellowish fluid that is a significant sign of strep infection. The most common form of group A strep infection is pharyngitis, better known as "strep throat."Sore throat appears to be a bad indicator of Streptococcus pharyngitis in the general population" (3-pp 231). It causes the inflammation and swelling of throat and tonsils. If not treated properly, it can spread to the respiratory tract and into the lung where it can develop into pneumonia.

It often spreads through direct contact. It is more common in schools where children share toys and food. Many other diseases can developed from group A strep infections, such as skin condition called impetigo followed by a kidney condition called glomerulonephritis. In its worst case, group A strep can cause a deadly disease.

If ignored on its first signs of infection, it becomes more virulent and spreads to deeper tissues of the body. The second best-known Streptococcus is group B strep. "Most human group B Streptococci inhibit the lower GI and female genital tracts and belong to the species Streptococcus " (1-pp 150). For that reason newborn babies are susceptible to group B strep infection. In some cases, mother can be vaccinated or even treated with antibiotic prior to pregnancy.

The problem is, in most cases the infection does not show any symptoms. "If the mother, and therefore the baby, lack protective antibody, the Streptococci can invade the mucosa and, in some cases, enter the blood stream". (1-pp 150). Meningitis and neonatal sepsis are two diseases that are frequently caused by group B strep.

Meningitis can also be caused by another strain of strep called Streptococcus. "Streptococcus is a common inhabitant of the oral mu sosa that has been associated with infection in different sites. Meningeal infection by this species, generally related to or iatrogenic". (4). There are some other strains of strep that can be infectious, but fewer cases are reported compared to strep A and B. Different strains of Streptococci produces different results. For that reason, the first test that can separate a beta from alpha is to perform blood agar test.

"Sheep blood is the blood of choice for primary isolation. It contains a factor that inhibits growth of Haemophilus, which is an organism commonly present in "normal" throats and is easily confused macroscopically with the appearance of beta streptococci " (2). Groups A, B, C, F and G are usually beta. These groups are equipped with the toxic enzyme, hemolysin, that has the ability to completely lyse the red blood cell (erythrocyte), creating a clear zone around the colonies. On the other hand, alpha strep such as group D and S. pneumonia e are alpha. They also lyse red blood cells, but they do it partially, leaving a greenish zone around the colonies.

Streptococcus is catalase negative. The catalase test is often used to distinguish between strep and staph. If we want to differentiate between different strains of steps, however, we need to do further tests. "The bacitracin susceptibility test is used for the presumptive identification of group A beta streptococci" (5). A BAP is inoculated by using three phase streaking method and a bacitracin disc is placed on the area between phase one and two.

The plate is incubated in 35^0 C for 48 hours. A zone of inhibition greater than 14 mm would be considered a positive or, in other words, susceptible. Among all groups of Streptococcus only group A is susceptible to bacitracin. A positive susceptibility result is clearly indicative of Group A strep. If the result was not positive, then further tests must be done to find other strains. One such a test is called hydrolysis, another is the CAMP reaction.

"Group B streptococci can hydrolyze into its component, glycine and benzoic acid" (5- pp. 608). A positive reaction will give a deep blue color, which is indicative of group B strep. CAMP test is routinely used to identify group B strep. "Group B Streptococci secrete a protein called "CAMP factor" that interacts with the beta- hemolysin produced and secreted by S. aureus to cause enhanced or synergistic hemolysis" (5-pp. 608). When the beta-hemolysin and CAMP factor diffuse into the medium, they interact with each other.

This interaction results in production of an arrow-shape area that shows a presumptive group B strep. Several other tests are available for identification of group D or pneumococci. Bile es culin and 6.5% Na Cl test are often used for group D, and susceptibility test is often used for identification of pneumococci. Treatment available for Streptococcus infections is often antibiotic administration. Since Streptococcus is a gram-positive bacterium, it has a thick layer of in its cell wall. Penicillin is probably one of the oldest drugs that have been discovered to kill streptococci bacteria.

It is vital for Streptococcus to synthesize without any interruption. Penicillin can prevent the cross-linking of peptide chain that makes the. Without this thick layer of, streptococci are more prone to being and less resistant to lytic enzymes such as lysozyme. Along with penicillin treatment, the patient should be well rested for about two weeks to eradicate the disease. "Clearly, a Streptococcus vaccine would be desirable. One approach to strep A vaccine is to evoke the type-specific anti-Antibody that opsonize streptococci of that sero type and protect against infection" (1-pp. 150).

Prevention is the best method of choice for not becoming infected. There are several steps that individuals can take to protect themselves from infection. Avoiding direct contact with infected person is the best policy. In schools, strep infected children must be separated from the others. Strep can be transmitted through the use and sharing of objects such as towel. Bacteria replicate in a fast pace, and have a high rate of mutation.

For that reason, more and more strep strains are becoming drug resistant. Recently in mice experiments in a lab setting "administration of via the peritoneum and air pouch at 3 h post-S. pyogenes infection was able to protect 33% of mice from death. Furthermore, was able to directly inhibit in vito growth of S. pyogenes. These data suggest that can be considered an antimicrobial agent for group A streptococcus infection" (6). Streptococcus is the microbial agent that commonly causes strep throat. There are different kinds of Streptococcus.

Three kinds that are more common are strep A, B and pneumococci. Since each can infect a specific location in the body, it is important to find and differentiate one from the other. Hemolysis of red blood cell is the best method of finding whether the strep is alpha or beta. Further tests such as bacitracin susceptibility, CAMP test, susceptibility and salt tolerance can be used to find the specific strep strain. Group A strep is the most common form of strep infection that causes "strep throat". Group B strep mostly reside in female genital tracts and causes neonatal infection.

To treat strep infection, penicillin or penicillin-derivative drugs are the best choices to eradicate the infection. Vaccination can also prevent strep infection. The best way to combat strep infection is to stay away from it. Washing hands and staying away from infected individuals can dramatically decrease the chance of being infected with strep.