Nosocomial group A streptococcal infections associated with asymptomatic health-care workers--Maryland and California, 1997.
(9/3842)
Group A Streptococcus (GAS), a common cause of pharyngitis and uncomplicated skin and soft tissue infections, can cause serious invasive infections (including necrotizing fasciitis and streptococcal toxic-shock syndrome [STSS]) and death. Since 1965, at least 15 postoperative or postpartum GAS outbreaks attributed to asymptomatic carriage in health-care workers (HCWs) have been reported. This report describes two nosocomial outbreaks of GAS infection in Maryland and California during 1996-1997; the findings suggest that early infection-control measures that include active surveillance may interrupt transmission and prevent morbidity and mortality. (+info)
The flesh-eating bacterium: what's next?
(10/3842)
Since the 1980s, there has been a marked increase in the recognition and reporting of highly invasive group A streptococcal (GAS) infections associated with shock and organ failure, with or without necrotizing fasciitis. Such dramatic cases have been defined as streptococcal toxic shock syndrome (StrepTSS). Strains of GAS isolated from patients with invasive disease have been predominantly M types 1 and 3, which produce either pyrogenic exotoxin A or B or both. The clinical and demographic features of streptococcal bacteremia, myositis, and necrotizing fasciitis are presented and compared with those of StrepTSS. Current concepts in the pathogenesis of invasive streptococcal infection will be presented, with emphasis on the interaction between GAS virulence factors and host defense mechanisms. Finally, new concepts in the treatment of StrepTSS will be discussed. (+info)
Extracellular cysteine protease produced by Streptococcus pyogenes participates in the pathogenesis of invasive skin infection and dissemination in mice.
(11/3842)
The role of an extracellular cysteine protease encoded by the speB gene in group A Streptococcus (GAS) skin infection was studied with a mouse model. Mice were injected subcutaneously with a wild-type GAS serotype M3 strain or a cysteine protease-inactivated isogenic derivative grown to stationary phase. The mortality rate of mice injected with the M3 speB mutant strain was significantly decreased (P < 0.0008) compared to that of animals injected with the wild-type parental organism. The abscesses formed in animals infected with the cysteine protease mutant strain were significantly smaller (P < 0.0001) than those caused by the wild-type organism and slowly regressed over 3 to 4 weeks. In striking contrast, infection with the wild-type GAS isolate generated necrotic lesions, and in some animals the GAS disseminated widely from the injection site and produced extensive cutaneous damage. All of these animals developed bacteremia and died. GAS dissemination was accompanied by severe tissue and blood vessel necrosis. Cysteine protease expression in the infected tissue was identified by immunogold electron microscopy. These data demonstrate that cysteine protease expression contributes to soft tissue pathology, including necrosis, and is required for efficient systemic dissemination of the organism from the initial site of skin inoculation. (+info)
Risk factors in the pathogenesis of invasive group A streptococcal infections: role of protective humoral immunity.
(12/3842)
An impressive change in the epidemiology and severity of invasive group A streptococcal infections occurred in the 1980s, and the incidence of streptococcal toxic shock syndrome cases continues to rise. The reason for the resurgence of severe invasive cases remains a mystery-has there been a change in the pathogen or in host protective immunity? To address these questions, we have studied 33 patients with invasive infection caused by genotypically indistinguishable M1T1 strains of Streptococcus pyogenes who had different disease outcomes. Patients were classified as having severe (n = 21) and nonsevere (n = 12) invasive infections based on the presence or absence of shock and organ failure. Levels of anti-M1 bactericidal antibodies and of anti-streptococcal superantigen neutralizing antibodies in plasma were significantly lower in both groups than in age- and geographically matched healthy controls (P < 0.01). Importantly, the levels of these protective antibodies in plasma samples from severe and nonsevere invasive cases were not different. Together the data suggest that low levels of protective antibodies may contribute to host susceptibility to invasive streptococcal infection but do not modulate disease outcome. Other immunogenetic factors that regulate superantigen responses may influence the severity of systemic manifestations associated with invasive streptococcal infection. (+info)
Cerebral arterial lesions resulting from inflammatory emboli.
(13/3842)
In order to study the effects of septic embolism on the brain, silicone rubber emboli of various types were injected into the carotid arteries of 35 dogs. Pathologic and angiographic studies were performed to assess the resultant arterial and parenchymal lesions. Pure silicone rubber emboli (14 dogs) produced occasional intra-arterial thrombosis but no arteritis. Sterile and bacterially contaminated emboli containing a lead-chromate pigment (similar to those used in previous studies of septic embolism) (11 dogs) and pure silicone rubber emboli with transversely oriented canals (10 dogs), after brief placement in a bacterial suspension, were associated with intense inflammatory arteritis. This was accompanied by focal meningitis, subarachnoid hemorrhage, thrombosis, and cerebritis of the underlying cortex. The findings resembled those found in mycotic aneurysm. Aneurysmal dilatation was observed in one postmortem angiogram. In previous models of mycotic aneurysm, the inflammation attributed to bacterial contamination was probably due to the lead-chromate pigment used. (+info)
Enterococcal endocarditis: duration and mode of treatment.
(14/3842)
This report summarizes data on sixteen patients with enterococcal endocarditis treated with penicillin and streptomycin. The experience reported suggests that a four week period is adequate for routine therapy in these patients, as in other forms of streptococcal endocarditis. It provides an additional group of patients successfully treated with penicillin and streptomycin. Two relapses were encountered. One of these received inadequate daily doses of penicillin. The other patient was clearly a failure of penicillin and streptomycin, but the failure in this instance could not be attributed to foreshortened treatment (6 weeks) or to high level streptomycin resistance of the infecting strain of Enterococcus. (+info)
Clinical and epidemiological features of group A streptococcal bacteraemia in a region with hyperendemic superficial streptococcal infection.
(15/3842)
Reports of increasing incidence and severity of invasive group A streptococcal (GAS) infections come mainly from affluent populations where exposure to GAS is relatively infrequent. We conducted a 6-year retrospective review of GAS bacteraemia in the Northern Territory of Australia, comparing the Aboriginal population (24% of the study population), who have high rates of other streptococcal infections and sequelae, to the non-Aboriginal population. Of 72 episodes, 44 (61%) were in Aboriginal patients. All 12 cases in children were Aboriginal. Risk factors were implicated in 82% of episodes (91% in adults) and there was no significant difference in the proportion of Aboriginal compared to non-Aboriginal patients with at least one risk factor. Genetic typing of isolates revealed no dominant strains and no evidence of a clone which has been a common cause of these infections elsewhere. (+info)
Proteinuria is associated with persistence of antibody to streptococcal M protein in Aboriginal Australians.
(16/3842)
Aboriginal communities in Northern Australia with high rates of group A streptococcal (GAS) skin infection in childhood also have high rates of renal failure in adult life. In a cross-sectional study of one such high risk community, albuminuria was used as a marker of renal disease. The prevalence of albuminuria increased from 0/52 in subjects aged 10-19 years to 10/29 (32.9%) in those aged 50 or more (P < 0.001). Antibodies to streptococcal M protein, markers of past GAS infection, were present in 48/52 (92%) at ages 10-19 years, 16/32 (50%) at ages 30-39, and 20/29 (69%) in those aged 50 or more. After allowing for the age-dependencies of albuminuria and of M protein antibodies (P < 0.001) albuminuria was significantly associated with M protein antibodies (P < 0.01). Thus, 72% of adults aged 30 or more with M protein antibodies also had albuminuria, compared with only 21% of those who were seronegative. More detailed modelling suggested that although most Aboriginal people in this community developed M protein antibodies following GAS infection in childhood, the development of proteinuria was associated with the persistence of such seropositivity into adult life. The models predicted that proteinuria developed at a mean age of 30 years in seropositive persons, at 45 years in seronegative persons who were overweight, and at 62 years in seronegative persons of normal weight. We demonstrated a clear association between evidence of childhood GAS infection and individual risk of proteinuria in adult life. This study provided a strong rationale for prevention of renal disease through the more effective control of GAS skin infections in childhood and through the prevention of obesity in adult life. (+info)