infectious diseases
Streptococcal Infections
Diseases Caused by Streptococci
The most significant streptococcal pathogen isS. pyogenes, which is beta-hemolytic and in Lancefield group A and is thus denoted as group A beta-hemolytic streptococci (GABHS). Themost common acute diseases due to GABHSare Tonsillopharyngitis None Overview of Bacterial Skin Infections None In addition, delayed, nonsuppurative complications ( Rheumatic Fever , GABHS can spread through the affected tissues and along lymphatic channels (causing Lymphangitis ) to regional lymph nodes (causing Other serious GABHS infections include septicemia, puerperal sepsis, Infective Endocarditis , Disease caused by other streptococcal speciesis less prevalent and usually involves soft-tissue infection or endocarditis (see table*). Some non-GABHS infections occur predominantly in certain populations (eg, group B streptococci in neonates and postpartum women). GABHS are the most common cause of acute-onset bacterial pharyngitis. Other bacterial causes include groups C and G streptococci andFusobacterium necrophorum. Most patients with GABHS pharyngitis are children between 3 years and 14 years of age who present with acute onset of sore throat, fever, beefy-red pharynx, and purulent tonsillar exudate. GABHS pharyngitis is rare in children younger than 3 years of age. The cervical and submaxillary nodes may enlarge and become tender. Streptococcal pharyngitis can lead to Peritonsillar Abscess and Cellulitis . Cough, laryngitis, and stuffy nose are not characteristic of streptococcal pharyngeal infection; their presence suggests another cause (usually viral or allergic). Humans are the primary reservoir for group A streptococci, which spread person-to-person via saliva or nasal secretions from an infected person. An asymptomatic carrier state may exist in as many as 20% of people. Scarlet fever, a predominantly childhood disease, usually follows a pharyngeal streptococcal infection; less commonly, it follows streptococcal infections at other sites (eg, the skin). Scarlet fever is caused by group A streptococcal strains that produce an erythrogenic toxin, leading to a diffuse pink-red cutaneous flush that blanches with pressure. The rash is seen best on the abdomen or lateral chest and as dark red lines in skinfolds (Pastia lines) or as circumoral pallor. The rash consists of characteristic numerous small (1- to 2-mm) papular elevations, giving a sandpaper quality to the skin. The upper layer of the previously reddened skin often desquamates after fever subsides. The rash usually lasts 2 to 5 days. Transmission of scarlet fever is enhanced in environments that result in close contact among people (eg, in schools or day care centers). Scarlet fever is not as common as it was in the past, but in recent years there have been a number of significant outbreaks in the United States, Europe, and China. For example, since 2014 there has been an unprecedented and persistent increase in scarlet fever in England with the highest incidence for nearly 50 years. Over a century ago, scarlet fever was feared as a potentially lethal disease. Its mortality and morbidity waned, however, well before antibiotics became available. Since the advent of antibiotic therapy, the mortality rate of treated scarlet fever is < 1% ( Scarlet fever reference ). A strawberry tongue (inflamed papillae protruding through a bright red coating) also occurs and must be differentiated from that seen in Toxic Shock Syndrome (TSS) and Other symptoms are similar to those in streptococcal pharyngitis, and the course and management of scarlet fever are the same as those of other group A infections. 1.Lamagni T, Guy R, Chand M, et al: Resurgence of scarlet fever in England, 2014-16: A population-based surveillance study.Lancet Infect Dis18(2):180–187, 2018. doi: 10.1016/S1473-3099(17)30693-X Skin infections include Impetigo and Ecthyma None Erysipelas None Cellulitis None Impetigois a superficial skin infection that causes crusting or bullae. Erysipelas None Cellulitis None This photo shows the focal erythema and swelling, usually accompanied by warmth and tenderness, characteristic of focal cellulitis. Note the clinician has marked the border of the cellulitis with a pen, to facilitate recognition of spread or resolution. © Springer Science+Business Media This photo shows the focal redness and swelling of the lower leg, usually accompanied by warmth and tenderness, characteristic of focal cellulitis. The clinician has marked the border of the cellulitis with a pen, to facilitate recognition of spread or resolution. Note the line of redness extending up the thigh due to lymphangitis. © Springer Science+Business Media © Springer Science+Business Media Necrotizing Soft-Tissue Infection due to Necrotizing fasciitis is prevalent among people who use injection drugs. Formerly known as streptococcal gangrene and popularized as the flesh-eating bacteria, the same syndrome may also be polymicrobial, involving a host of aerobic and anaerobic flora, includingClostridium perfringens. Polymicrobial infection is likely when the source is the bowel (eg, after intestinal surgery, bowel perforation, diverticulitis, or appendicitis). Symptoms of necrotizing fasciitis begin with fever and exquisite localized pain out of proportion to physical findings; pain increases rapidly over time and is often the first (and sometimes only) manifestation. Diffuse or local erythema may be present. Thrombosis of the microvasculature causes ischemic necrosis, leading to rapid spread and disproportionally severe toxicity. In 20 to 40% of patients, adjacent muscles are invaded. Shock and renal dysfunction are common. Mortality is high, even with treatment. Streptococcal toxic shock (TSS), similar to that caused by Patients are usually otherwise healthy children or adults with skin and soft-tissue infections. Predisposing risk factors for TSS in patients infected with these toxin-producing strains include diabetes, alcohol use disorder, penetrating and nonpenetrating trauma, surgical procedures, and varicella infection. An initial influenza-like prodrome is followed by high fever, tachycardia, tachypnea, and severe pain. Tissue necrosis, shock, disseminated coagulation, and multisystem organ failure follow. The mechanism by which certain strains of GABHS cause delayed complications is unclear but may involve cross-reactivity of streptococcal antibodies against host tissue. Rheumatic Fever , Diagnosis of a first episode is based on a combination of arthritis, carditis, chorea, specific cutaneous manifestations, and laboratory test results (Jones criteria—see table). One of the most important reasons for treating GABHS pharyngitis (strep throat) is to prevent rheumatic fever. Postinfectious Glomerulonephritis (PIGN) None (pediatric autoimmune neuropsychiatric disorder associated with streptococcal infections) refers to a subset of Obsessive-Compulsive Disorder (OCD) and Related Disorders in Children and Adolescents or Psoriasis None 