microbiology

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Date

Course

Review of Deadly Disease and Epidemics Series` Streptococcus (group A

The author of `Deadly Disease and Epidemics Series` Streptococcus (group A . Tara C . Smith is an assistant professor at Iowa University She has spent the bulk of her higher education studying the effects of gram positive bacteria including streptococco group A bacteria Streptococcus pyogenes (Group A streptococcus ) is present in microbiota of 5-15 of humans , usually in respiratory tract , usually not producing obvious disease . Diseases can occur when host is compromised Streptococcal membranes contain some antigens very

similar to antigens in human muscle and nerve tissues , which can lead to reduced immunological activity by host "molecular mimicry

Members of the genus Streptococcus are spherical gram positive bacteria . They are probably responsible for more illnesses and causes a greater variety of disease than any other type of bacteria . Among the disease caused by streptococci are scarlet fever , pharyngitis , and pneumococcal pneumnia . Streptococci typically appear in the chains that can contain four or six cocci or as many as fifty or more

Infection with group A streptococci results in a number of related clinical disease entities such as streptococcal throat , scarlet fever erysipelas , nonsuppurative complications , nephritis , and rheumatic fever . The type of disease resulting from group A streptococci depends on the site of tissue invasion , the antigenic characteristics of the infecting strain of streptococcus and the immune statue of the host There are approximately 75 serologically distinct strains of group A streptococci producing a variety of different enzymes and at least three different erythrogenic toxins

The antigenic characteristics determine the type of enzyme specific and toxin specific antibodies produced by the host . A host with adequate antibodies against a particular serotype with or without antitoxic immunity may develop no clinical disease if reinfected with the same serotype . A person with antitoxic immunity resulting from previous group A infections but with no antibodies against a particular invading serotype may develop a clinical streptococcal throat . A person with no antitoxic immunity and no antibodies against an invading toxigenic group A streptococcus may develop clinical scarlet fever . In all clinical streptooccal disease a leukocytosis is present

Streptococcal throat is an acute exudative tonsillitis or pharyngitis caused by group A bet-hemolytic streptococci . Coincident or subsequent otitis media or peitonsillar abcess may be present . Rheumatic fever chorea , and acute glomerulonephritis are possible . Scarlet fever is a group A bet-hemolytic streptococcal disease characterized by a skin rash . It occurs when the infecting strain of streptococcus produces a toxin , causing a sensitivity reaction in the infected host . Clinical characteristics may include those of strep through with enathem strawberry tongue , and exanthem . Rheumatic fever is a sequela of group A streptococcal infection of the upper respiratory tract , occur in about 2 .8 of those having a strep throat . The condition is thought to result from an altered immune system reaction

I thought this book was well written and Smith was an articulate writer . She was able to make accessible a number of concepts to me She had...