Types of streptococcus infection

Article by James Cooper

All Streptococcus bacteria look alike under the microscope. They are also hard to distinguish in microbiological cultures. Thus, it is almost impossible to tell them apart by looking at them, and instead, metabolic tests must be used to distinguish the various bacteria of the Streptococcus group. This is unlike the two groups of Staphylococcus,which have different colors in culture. Scientists believe that there are at least 40 confirmed types of Streptococcus, each having a few different strains. Scientists divide the 40 or more different types into 2 groups called clusters. Initially, the degree of hemolysins produced by the bacteria defined the clusters. Some Streptococcus do not produce any hemolysins and thus are nonhemolytic. Others produce either alpha or beta hemolysis. A beta-hemolytic Streptococcus produces the most severe effects in the body. A later method, called Lancefield grouping, categorized the types of Streptococcus based on immunological testing called serotyping. A particular Lancefield group refers to a protein antigen found on the surface of the bacteria. A combination of characteristics, including where the bacteria appear, presently determines the clusters. The clusters are the anginosus group, the bovis group, the mitis group, the mutans group, the pyogenic group, and the salivarius group. Streptococcus anginosus and a host of relatives make up the anginosus group. These alpha-hemolytic bacteria are commoninhabitants of the mouth and nose and do not cause disease. They are part of the A, F, and G Lancefield groups The bovis group consists of an intestinal bacterium called Streptococcus bovis. As its name implies, scientists isolated it from the intestinal tract of cattle. These Streptococci are alpha- or nonhemolytic and related to other Streptococcus bacteria specific to particular animals. Most cause no harm in their host animals. However, they can infect wounds and cause septic diseases. They have a D Lancefield grouping. The mitis group contains a diversity of alpha-hemolytic bacteria in the H and O Lancefield groups. Most live in the respiratory systems of humans and animals without causing disease. These bacteria can cause some types of pneumonia. Streptococcus pneumoniae, which causes human respiratory diseases, is a pathogen in the mitis group. The mutans group has no hemolysins and does not belong to a designated Lancefield group. They live in the mouths of many animals, where they glue themselves to the teeth. Many of them are involved in tooth decay and possibly gum disease. Streptococcus salivarius appropriately appears in the salivarius group. Like the mutans-group bacteria, they live in the mouth and do not produce hemolysin. It belongs to the K Lancefield group. The pyogenes group contains the bacterium that causes StrepTSS. These bacteria are beta-hemolytic and are highly capable of causing severe reactions. They are part of the A, B, and C Lancefield groups. Included in the pyogenes group are Streptococcus algalactiae, Streptococcus equisimilis, and Streptococcus pyogenes. Streptococcus algalactiae is a contagious bacterium ofmammals. It commonly causes ear, sinus, and throat infections of domesticated animals and humans. People who work with animals are likely to contract infections from this bacterium. In the 1960s, Streptococcus algalactiae became a leading cause of disease in human babies.Streptococcus equisimilis has several strains found in many mammals. They cause diseases similar to toxic shock syndrome in animals and humans. The bacteria spread thoughout the body causing high fever and damage to internal organs. Streptococcus pyogenes is the culprit that produces StrepTSS and other diseases in humans. Researchers also called it Streptococcus hemolyticus, Streptococcus erysipelatos, Streptococcus scarlatinae, and Micrococcus scarlatinae until they confirmed that all were the same bacterium. Their small size and the high variability of traits make bacteria difficult to identify.

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Tags: infection, streptococcus, Types