Streptococcal Infections

CHAPTER 34 Streptococcal Infections Barry M. Gray 1. Introduction coccus is now a separate genus but will be considered an honorary streptococcus in this chapter because of its sim The streptococci are a large heterogeneous group of gram ilarities to enteric streptococci. The enterococcus is part of positive spherically shaped bacteria found widely distrib the normal bowel flora and has been increasingly isolated uted in nature. They include some of the most important as an opportunistic invader, especially in nosocomial in agents of human disease, as well as members of the fections (see Chapter 25). This chapter will focus mainly normal human flora. Some streptococci have been associ on group A and B streptococci and will include current ated mainly with disease in animals, while others have information on pneumococci and other streptococci asso been domesticated and used for the culture of buttermilk, ciated with human disease. Further details on S. pneu yogurt, and certain cheeses. Those known to cause human moniae may be found in Chapter 28. disease can be thought of as comprising two broad catego ries: First are the pyogenic streptococci, including the familiar [3-hemolytic streptococci and the pneumococcus. 2. Historical Background These organisms are not generally part of the normal flora but cause acute, often severe, infections in normal hosts. Streptococcal infections were recognized by Greek Second are the more diverse enteric and oral streptococci, physicians by the 3rd century B.C. A description of which are nearly always part of the normal flora and which erysipelas is recorded in Epidemicus and attributed to are more frequently associated with opportunistic infec Hippocrates. In the Middle Ages, scarlet fever, or "scar tions. latina," as it was called in Italy, was an eye-catching and Measured in terms of mortality, morbidity, and eco notable disease. Sydenham's description in 1676 clearly nomic costs, five streptococcal species are of major im differentiated this disease from measles and other rashes, portance in human disease. (1) The group A streptococcus, but it was not until 1924 that G.F. and G.H. Dick showed Streptococcus pyogenes, produces a wide range of infec conclusively that streptococci were the causative agents. tions, from pharyngitis and impetigo to puerperal sepsis Until the advent of penicillin, childbed fever, or puerperal and erysipelas. Their non suppurative sequelae include sepsis, remained one of the most frequent causes of death acute rheumatic fever and acute glomerulonephritis. among otherwise healthy young women. The classic (2) The group B streptococcus, S. agalactiae, is currently works of Holmes, in 1858, and Semmelweis, in 1861, a leading cause of sepsis in newborn infants and a frequent described the transmission of this disease and provided cause of postpartum infections in mothers. (3) The pneu guidelines for effective preventive measures that are still mococcus, S. pneumoniae, remains the most frequent applicable today. Rheumatic fever was first described by cause of bacterial pneumonia in all age groups and is a Wells in 1812, and Bouillaud described the association of common agent in otitis media, bacteremia, and men acute rheumatism and heart disease in 1835. In 1836, ingitis. (4) Among the oral streptococci, S. mutans is Bright published his account of "renal disease accom important as a principal agent of dental caries. (5) Entero- panied with secretion of albuminous urine."(l) Osler pro vided detailed descriptions of "malignant scarlet fever," Barry M. Gray • Division of Medical Education, Spartanburg Re which remained common until the advent of antibiotics gional Medical Center, Spartanburg, South Carolina 29303. (see Fig. 1). Severe invasive disease, including necrotizing 673 A. S. Evans et al. (eds.), Bacterial Infections of Humans © Springer Science+Business Media New York 1998 674 Part II • Acute Bacterial Infections 7000 14 c 0 :;::: 6000 !! Scarlet Fever - Number of Deaths 12 ::s .- Q. II) l 0 .c 5000 i a.. (IJ '\ \ 10 -Q) !i 0 C :: 0 '\ 0 4000 .... \ 0 .... 0 - , 8 0,.. "- Q) V \ ... .c 3000 \ Q) E :: 6 Q. ::s \ Z Q) 2000 \ ...4~ 4 (IJ Streptococcal Sore Throat ~- VI Nurrber of Deaths .c 1000 2 (IJ 50"'" F,,,,,,- -Q) D'~h R~'~ C III' ·........ t 0 ............. 0 1905 1915 1925 1935 1945 1955 1965 1975 Recorded Data 1910-1940 Resident Data 1940-1975 Figure 1. The number of deaths (left-hand scale) from scarlet fever (1900-1960) and from all streptococcal sore throat (1950-1975), with death rates (right-hand scale) per 100,000 population in the United States. Appropriate comparability ratios were applied beginning in 1940, and recorded data compiled according to the geographic locale where the event occurred without regard to residence (1900-1940); resident data were compiled according to the usual place of residence without regard to locale where the event occurred (1940-1975). The population used for determining rates was that of the registration area. Data were not available for streptococcal sore throat for 1900-1950. The number of states reporting for 1900-1905 was 10, gradually increasing to 48 in 1935 and to 50 states in 1960. After 1975, reporting was optional, and no accurate data are available. Sources of data: US Bureau of the Census, Historical Statistics of the United States: Colonial Times to 1970, Bicentennial ed., Part I, p. 77, 1975; National Office of Vital Statistics, Vital Statistics Reports, Vol. 37, No.9 (1920-1950); Centers for Disease Control, Morbidity and Mortality Weekly Report, Annual Supplement, 1960 and 1970. Figure redrawn from Quinn.(l) fasciitis, "hemolytic streptococcus gangrene," and myo descriptive value than the term "S. haemolyticus," which sitis, was much less common and did not appear in the was commonly used through the early part of this century. medical literature until the second and third decades of The formal classification of streptococci began when this century. During the mid-1970s to 1980s, cases of acute blood agar came into use and the hemolytic properties of rheumatic fever and acute glomerulonephritis became ex various organisms were noted. In 1919, Brown used the ceedingly rare (see Fig. 2), and streptococcal disease term "beta" to describe streptococci that produced a 2- to seemed only an inconvenience. By the late 1980s, how 4-mm zone of clear hemolysis around colonies grown on ever, rheumatic fever made a dramatic reappearance, blood agar. "Alpha" streptococci were those producing along with an increase in severe invasive infections and incomplete, greenish hemolysis. Most of the isolates from the emergence of a streptococcal toxic shock syn severe human disease were f3-hemolytic. It was not until dromep-4) Group A streptococci made the headline in the 1928, when Lancefield introduced methods of serotyping popular press as "killer strep," the "flesh-eating bacte streptococci based on immunologic reactions with cellu ria. " lar components, that groups and types within groups could In the late 19th century, many investigators contrib be clearly distinguished. The group antigens were eventu uted to the understanding of streptococci and their relation ally shown to be specific cell wall carbohydrates. The to human disease. By the 1880s many species had been group A streptococci were further differentiated by the M given names such as S. epidemicus, S. erysipelatus, S. and T protein antigens. The f3-hemolytic streptococci scarlatinae, and S. rheumaticus, which reflected different from most human infections proved to be those of group manifestations of streptococcal infection. The name S. A. Armed with these new epidemiological tools, Lance pyogenes dates from this period but is probably of less field and Hare(5) investigated cases of puerperal sepsis Chapter 34 • Streptococcal Infections 675 Number of Positive Number of Cases Throat Cultures __ Rheumatic Fever ......... Glomerulonephritis 8000 40 7000 35 6000 30 5000 25 4000 20 3000 15 2000 10 1000 5 o+-~~-,~~~~~~~~~~~~~~~~~-+o 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 YEAR Figure 2. The number of positive throat cultures (left-hand scale and number of confirmed cases of rheumatic fever and acute glomerulonephritis (right-hand scale) seen in private pediatirc practices participating in streptococcal surveillance studies in Rochester, New York, 1967-1988. The data were kindly provided by Caroline Breese Hall, University of Rochester. at Queen Charlotte's Hospital in London, beginning in the nized as perinatal pathogens for over 20 years. Rather, early 1930s. Of 46 cases of postpartum sepsis, all but one there seems to have been a real increase in group B isolate was group A, and the exception was identified as disease, beginning in the United States and Europe during the prototype of a new serological group, designated the 1960s. By the mid-1970s, numerous reports of group B group G. A year earlier, Hare and Colebrook observed that disease appeared in the literature, and the group B strep hemolytic streptococci resembling those associated with tococcus was said to have come of age'<6,7) sepsis were never found in vaginal cultures of healthy The pneumococcus has an interesting and important women, but that some women carried streptococci that history, beginning with its association with pneumonia resembled those isolated in bovine mastitis. The latter and later with developments in immunization and serum organisms proved to be members of streptococcus group therapy (see Chapter 28). Studies of the pneumococcus

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