Group A Streptococcus carriage among close contacts of patients with invasive infections

During the past few years, the incidence of invasive group A Streptococcus (GAS) infection has been increasing. However, there are presently no clear recommendations regarding antibiotic prophylaxis for close contacts of index patients. The aims of this study were 1) to determine the prevalence of carriage of the same GAS strain as the patient's among contacts of patients with invasive infections and 2) to assess the importance of exposure duration. From March 1995 to March 1996, the authors prospectively included in the study all patients with invasive GAS infection, as defined by the Working Group on Severe Streptococcal Infections, who came to H?pital Maisonneuve-Rosemont in Montreal, Quebec, Canada. An epidemiologic investigation was systematically carried out for each index case. Contacts were divided into two groups: those who had spent 24 hours or more with the index patient during the week preceding the beginning of his or her illness and those who had spent 12-24 hours with the index patient during that week. Strains of GAS were examined by serotyping (proteins M and T and the presence or absence of the serum opacity factor) and by characterization of streptococcal pyrogenic exotoxins (exotoxins A, B, and C). One hundred and two contacts of 17 index cases with invasive GAS infection were systematically screened. Contacts were considered positive if they carried the same strain of the bacterium and the same streptococcal pyrogenic exotoxin as the index case. Among the contacts who had spent at least 24 hours per week with their respective index cases, 13 out of 48 (27%) were found to be harboring the same serotype of GAS as the index patient (95% confidence interval 14.5-39.5). By comparison, only one of the 54 contacts in the 12- to 24-hour group (1.8%) was found to be carrying the same strain of the bacterium (95% confidence interval 0-5.3). This difference between the two groups was statistically significant (p<0.001). The median age of the positive carriers (10 years) was significantly lower than the median age of the noncarriers (39 years) (p< or =0.0005). This study showed that close contacts who had spent 12-24 hours with the index patient were rarely colonized with GAS. If antibiotic prophylaxis against GAS is recommended, it should probably target contacts who spent at least 24 hours with an infected patient during the week preceding illness onset.     

Invasive infections due to group A beta-haemolytic streptococci in two families

An invasive beta-haemolytic Lancefield group A streptococcal (GAS) infection was diagnosed in 4 patients: a 70-year-old woman, her 71-year-old husband, a 62-year-old woman and her 43-year-old son. In the married couple the infection was caused by GAS-type TB3264M100. The woman had a pneumonia, whilst her husband developed a streptococcal toxic shock-like syndrome; he died. The other woman and her son were infected with GAS-type T6M6. The son died of a circulatory arrest due to necrotizing fascitis from a wound in his arm. His mother recovered following a severe tonsillitis. The number of invasive GAS infections has increased in the past decades. GAS infections occur mostly in isolated cases, but clusters of patients are also seen, like the two described here. The risk of an invasive GAS-infection is greatest if one has been in the neighbourhood of the index patient during the week prior to the diagnosis in that patient. According to the latest (American) guidelines, there is no reason for prophylactic treatment of the close contacts of patients.     

Transmission of group A Streptococcus limited to healthcare workers with exposure in the operating room.

BACKGROUND: Nosocomial transmission of group A Streptococcus (GAS) has been well described. A recent report of an outbreak investigation suggested that transmission can be extensive and that standard infection control measures may not be adequate to prevent transmission from patients with severe, invasive disease to healthcare workers (HCWs). OBJECTIVE: A case of pharyngitis in an HCW caring for a patient with GAS pharyngitis and necrotizing fasciitis prompted an investigation of the extent and risk factors for nosocomial transmission of GAS. SETTING: A 509-bed, tertiary care center in Portland, Oregon with 631,100 patient visits (hospital and clinic) and 11,500 employees in the year 2003. METHODS: HCWs with exposure to the index patient ("contacts") were identified for streptococcal screening and culture and completion of a questionnaire regarding the location and duration of exposure, use of personal protective equipment, and symptoms of GAS infection. RESULTS: We identified 103 contacts of the index patient; 89 (86%) submitted oropharyngeal swabs for screening and culture. Only 3 (3.4%) of contacts had a culture that yielded GAS; emm typing results and pulsed-field gel electrophoresis patterns of GAS isolates from 2 HCWs were identical to those for the isolate from the index patient. Both HCWs were symptomatic, with febrile pharyngitis and reported prolonged contact with the open wound of the patient in the operating room. CONCLUSIONS: In this investigation, nosocomial transmission was not extensive, and standard precautions provided adequate protection for the majority of HCWs. Transmission was restricted to individuals with prolonged intraoperative exposure to open wounds. As a result, infection control policy for individuals was modified only for HCWs with exposure to GAS in the operating room.     

Risk for severe group A streptococcal disease among patients' household contacts

From January 1997 to April 1999, we determined attack rates for cases of invasive group A streptococcal (GAS) disease in household contacts of index patients using data from Active Bacterial Core Surveillance sites. Of 680 eligible index-patient households, 525 (77.2%) were enrolled in surveillance. Of 1,514 household contacts surveyed, 127 (8.4%) sought medical care, 24 (1.6%) required hospital care, and none died during the 30-day reference period. One confirmed GAS case in a household contact was reported (attack rate, 66.1/100,000 household contacts). One household contact had severe GAS-compatible illness without confirmed etiology. Our study suggests that subsequent cases of invasive GAS disease can occur, albeit rarely. The risk estimate from this study is important for developing recommendations on the use of chemoprophylaxis for household contacts of persons with invasive GAS disease.     

Meningites à streptocoque du groupe A

An increased incidence and severity of invasive group A streptococcus (GAS) infections over the past decade have been reported by several authors, but GAS remains an uncommon cause of bacterial meningitis. The aim of this study was to describe and analyze the clinical and biological data of GAS meningitis by reporting 10 new cases of pediatric GAS meningitis and making a literature review. The mean age of patients, seven girls and three boys, was 3 years. There was a history of preexisting or concomitant community-acquired infection in five patients over 10. The outcome was fatal in two cases. All patients received an initial empirical antimicrobial therapy with a third generation cephalosporin switched in six cases to amoxicillin. The prognosis for this type of streptococcal meningitis is usually good, but death may occur even in children without any identified risk factor for severe infection.     

Nosocomial group A streptococcal infections associated with asymptomatic health-care workers--Maryland and California, 1997

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.     

Invasive group A streptococcal infection in older adults in long-term care facilities and the community, United States, 1998-2003

Limited information exists on the incidence and characteristics of invasive group A streptococcal (GAS) infections among residents of long-term care facilities (LTCFs). We reviewed cases of invasive GAS infections occurring among persons > or =65 years of age identified through active, population-based surveillance from 1998 through 2003. We identified 1,762 invasive GAS cases among persons > or =65 years, including 1,662 with known residence type (LTCF or community). Incidence of invasive GAS infection among LTCF residents compared to community-based elderly was 41.0 versus 6.9 cases per 100,000 population. LTCF case-patients were 1.5 times as likely to die from the infection as community-based case-patients (33% vs. 21%, p<0.01) but were less often hospitalized (90% vs. 95%, p<0.01). In multivariate logistic regression modeling, LTCF residence remained an independent predictor of death. Additional prevention strategies against GAS infection in this high-risk population are urgently needed.     

Blunt trauma as a risk factor for group A streptococcal necrotizing fasciitis

PURPOSE: Anecdotal reports suggest that blunt trauma and seemingly innocuous musculoskeletal injuries (e.g., muscle strains) are risk factors for developing necrotizing fasciitis (NF) and myositis caused by group A Streptococcus and other bacteria; however, this hypothesis has not been tested in analytic epidemiologic studies of invasive group A streptococcal (GAS) disease. We conducted two case-control studies to determine whether nonpenetrating trauma is a risk factor for either NF or severe cellulitis caused by GAS. METHODS: A secondary analysis of patients who were hospitalized throughout Florida for invasive GAS disease during a 4-year period was conducted. Two case series were used. The first series comprised patients who had severe GAS cellulitis. The second were patients who had GAS NF. Case-patients were compared to a single control series composed of patients with invasive GAS disease not including either NF or cellulitis (e.g., primary bacteremia, septic arthritis). RESULTS: After we adjusted for age, race, and clindamycin usage, GAS NF cases were 5.97 times as likely as controls to have a recent history of blunt trauma (p = 0.04). Patients with severe cellulitis were not more likely than controls to have associated blunt trauma. CONCLUSIONS: Nonpenetrating trauma is significantly associated with the development of GAS NF.     

Distribution of emm genotypes among group A streptococcus isolates from patients with severe invasive streptococcal infections in Japan, 2001-2005

We surveyed emm genotypes of group A streptococcus (GAS) isolates from patients with severe invasive streptococcal infections during 2001-2005 and compared their prevalence with that of the preceding 5 years. Genotype emm1 remained dominant throughout 2001 to 2005, but the frequency rate of this type decreased compared with the earlier period. Various other emm types have appeared in recent years indicating alterations in the prevalent strains causing severe invasive streptococcal infections. The cover of the new 26-valent GAS vaccine fell from 93.5% for genotypes of isolates from 1996-2000 to 81.8% in 2001-2005.     

Invasive group A streptococcal infection and vaccine implications, Auckland, New Zealand

We aimed to assess the effect of invasive group A streptococcal (GAS) infection and the potential effects of a multivalent GAS vaccine in New Zealand. During January 2005-December 2006, we conducted prospective population-based laboratory surveillance of Auckland residents admitted to all public hospitals with isolation of GAS from normally sterile sites. Using emm typing, we identified 225 persons with confirmed invasive GAS infection (median 53 years of age; range 0-97 years). Overall incidence was 8.1 cases per 100,00 persons per year (20.4/100,000/year for Maori and Pacific Islanders; 24.4/100,000/year for persons >65 years of age; 33/100,000/year for infants <1 year of age). Nearly half (49%) of all cases occurred in Auckland's lowest socioeconomic quintile. Twenty-two persons died, for an overall case-fatality rate of 10% (63% for toxic shock syndrome). Seventy-four percent of patients who died had an underlying condition. To the population in our study, the proposed 26-valent vaccine would provide limited benefit.     

Interim UK guidelines for management of close community contacts of invasive group A streptococcal disease

Group A streptococci cause a wide range of illnesses from non-invasive disease such as pharyngitis to more severe invasive infections such as necrotising fasciitis. There remains uncertainty about the risk of invasive disease among close contacts of an index case of invasive disease and whether this risk warrants antibiotic prophylaxis. A 19-200 fold increased risk among household contacts has been reported in the literature. Recommendations for antibiotic prophylaxis regimens vary by country. A comprehensive literature review together with preliminary analysis of 2003 United Kingdom data from the strep-EURO programme informed the interim recommendations of an expert working group. The evidence base to formulate definitive guidance is weak. Risk calculations based on provisional UK data estimated that over 2,000 contacts would need to receive antibiotic prophylaxis to prevent a subsequent case of invasive group A streptococcal disease. The Working Group considered that currently available evidence did not warrant the routine administration of chemoprophylaxis to all close community contacts. More robust risk estimates will be derived from ongoing UK surveillance data to inform a review of this guidance in 2005.     

Clinical and epidemiological features of group A streptococcal bacteraemia in a region with hyperendemic superficial streptococcal infection

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.     

Nursing home outbreak of invasive group a streptococcal infections caused by 2 distinct strains.

OBJECTIVE: To identify factors contributing to a cluster of deaths from invasive group A streptococcus (GAS) infection in a nursing home facility and to prevent additional cases. DESIGN: Outbreak investigation. SETTING: A 146-bed nursing home facility in northern Nevada. METHODS: We defined a case as the isolation of GAS from a normally sterile site in a resident of nursing home A. To identify case patients, we reviewed resident records from nursing home A, the local hospital, and the hospital laboratory. We obtained oropharyngeal and skin lesion swabs from staff and residents to assess GAS colonization and performed emm typing on available isolates. To identify potential risk factors for transmission, we performed a cohort study and investigated concurrent illness among residents and surveyed staff regarding infection control practices. RESULTS: Six residents met the case patient definition; 3 (50%) of them died. Among invasive GAS isolates available for analysis, 2 distinct strains were identified: emm11 (3 isolates) and emm89 (2 isolates). The rate of GAS carriage was 6% among residents and 4% among staff; carriage isolates were emm89 (8 isolates), emm11 (2 isolates), and emm1 (1 isolate). Concurrently, 35 (24%) of the residents developed a respiratory illness of unknown etiology; 41% of these persons died. Twenty-one (30%) of the surveyed employees did not always wash their hands before patient contacts, and 27 (38%) did not always wash their hands between patient contacts. CONCLUSIONS: Concurrent respiratory illness likely contributed to an outbreak of invasive GAS infection from 2 strains in a highly susceptible population. This outbreak highlights the importance of appropriate infection control measures, including respiratory hygiene practices, in nursing home facilities.     

Toxic shock-like syndrome caused by streptococci]

Since the mid-eighties an increase of severe infections with invasive group A streptococci (GAS) has been noticed throughout the world, not only in the elderly but in healthy adults as well. The acute presenting infection starts with fever, enanthema, generalised erythema, rapidly progressing into shock and multiorgan failure, and is called streptococcal toxic shock syndrome (STSS). Despite surgical and antibiotic therapy with penicillin and clindamycin the mortality is high. There are as yet insufficient data in patients with STSS to decide between penicillin en clindamycin. Intravenous administration of high dose gammaglobulin, advocated in the USA, might neutralize the exotoxins, but the effectiveness of this therapy has not been established yet.     

High burden of invasive beta-haemolytic streptococcal infections in Fiji

We undertook a 5-year retrospective study of group A streptococcal (GAS) bacteraemia in Fiji, supplemented by a 9-month detailed retrospective study of beta-haemolytic streptococcal (BHS) infections. The all-age incidence of GAS bacteraemia over 5 years was 11.6/100,000. Indigenous Fijians were 4.7 times more likely to present with invasive BHS disease than people of other ethnicities, and 6.4 times more likely than Indo-Fijians. The case-fatality rate for invasive BHS infections was 28%. emm-typing was performed on 23 isolates: 17 different emm-types were found, and the emm-type profile was different from that found in industrialized nations. These data support the contentions that elevated rates of invasive BHS and GAS infections are widespread in developing countries, and that the profile of invasive organisms in these settings reflects a wide diversity of emm-types and a paucity of types typically found in industrialized countries.     

Streptococcal toxic-shock syndrome: spectrum of disease, pathogenesis, and new concepts in treatment.

Since the 1980s there has been a marked increase in the recognition and reporting of highly invasive group A streptococcal infections with or without necrotizing fasciitis associated with shock and organ failure. Such dramatic cases have been defined as streptococcal toxic-shock syndrome. Strains of group A streptococci isolated from patients with invasive disease have been predominantly M types 1 and 3 that produce pyrogenic exotoxin A or B or both. In this paper, the clinical and demographic features of streptococcal bacteremia, myositis, and necrotizing fasciitis are presented and compared to those of streptococcal toxic-shock syndrome. Current concepts in the pathogenesis of invasive streptococcal infection are also presented, with emphasis on the interaction between group A Streptococcus virulence factors and host defense mechanisms. Finally, new concepts in the treatment of streptococcal toxic-shock syndrome are discussed.     

Invasive group a streptococcal disease in nursing homes, Minnesota, 1995-2006

Nursing home residents are at high risk for invasive group A streptococcal (GAS) disease, and clusters of cases in nursing homes are common.To characterize the epidemiologic features of invasive GAS disease in nursing homes, we conducted active, statewide, population- and laboratory-based surveillance in Minnesota from April 1995 through 2006. Of 1,858 invasive GAS disease cases, 134 (7%) occurred in nursing home residents; 34 of these cases were identified as part of 13 clusters. Recognizing cases of GAS disease in nursing homes posed challenges. Measures to ensure identification of case-patients as residents of specific nursing homes need to be included in standard guidelines for the prevention and control of invasive GAS disease in this setting.     

Tightly clustered outbreak of group A streptococcal disease at a long-term care facility.

OBJECTIVE: To describe investigation of a tightly clustered outbreak of invasive group A streptococcal (GAS) disease associated with a high mortality rate in a long-term care facility (LTCF). DESIGN: Cross-sectional carriage survey and epidemiologic investigation of LTCF resident and employee cohorts. SETTING: A 104-bed community LTCF between March 1 and April 7, 2004. PATIENTS: A cohort of LTCF residents with assigned beds at the time of the outbreak. INTERVENTIONS: Reinforcement of standard infection control measures and receipt of chemoprophylaxis by GAS carriers. RESULTS: Four confirmed and 2 probable GAS cases occurred between March 16 and April 1, 2004. Four case patients died. The final case occurred during the investigation, before the patient was determined to be a GAS carrier. No case occurred during the 6 months after the intervention. Disease was caused by type emm3 GAS; 16.5% of residents and 2.4% of employees carried the outbreak strain. Disease was clustered in 1 quadrant of the LTCF and associated with nonintact skin. GAS disease or carriage was associated with having frequent personal visitors. CONCLUSIONS: Widespread carriage of a virulent GAS strain likely resulted from inadequate infection control measures. Enhanced infection control and targeted prophylaxis for GAS carriers appeared to end the outbreak. In addition to employees, regular visitors to LTCFs should be trained in hand hygiene and infection control because of the potential for extended relationships over time, leading to interaction with multiple residents, and disease transmission in such residential settings. Specific attention to prevention of skin breaks and proper wound care may prevent disease. The occurrence of a sixth case during the investigation suggests urgency in addressing severe, large, or tightly clustered outbreaks of GAS infection in LTCFs.     

Invasive group A streptococcal disease: risk factors for adults

We conducted a case-control study to identify risk factors for invasive group A streptococcal (GAS) infections, which can be fatal. Case-patients were identified when Streptococcus pyogenes was isolated from a normally sterile site and control subjects (two or more) were identified and matched to case-patients by using sequential-digit telephone dialing. All participants were noninstitutionalized surveillance area residents, >18 years of age. Conditional logistic regression identified the risk factors for invasive GAS infection: in adults 18 to 44 years of age, exposure to one or more children with sore throats (relative risk [RR]=4.93, p=0.02), HIV infection (RR=15.01, p=0.04), and history of injecting drug use (RR=14.71, p=0.003); in adults >45 years of age, number of persons in the home (RR=2.68, p=0.004), diabetes (RR=2.27, p=0.03), cardiac disease (RR=3.24, p=0.006), cancer (RR=3.54, p=0.006), and corticosteroid use (RR=5.18, p=0.03). Thus, host and environmental factors increased the risk for invasive GAS disease.     

Invasive Lancefield group A streptococcal infections in the Netherlands

After a steady decrease in morbidity and mortality resulting from severe group A streptococcal (GAS) infections, the 1980s witnessed a resurgence of invasive GAS disease. As a result a nationwide laboratory-based surveillance for invasive GAS infections was conducted at the National Institute of Public Health (RIVM) from 1994 to 2003. The estimated annual incidence ranged from 2.0 to 4.0 cases per 100,000 individuals per year. The case-fatality rate was 18% overall but varied substantially depending on the manifestation of the disease. GAS infections may be complicated by toxic shock-like syndrome (TSS) which is caused by bacterial exotoxins. Case fatality among TSS cases was 59%. The M-protein that extends from the cell membrane is used for sub-typing GAS in > 150 different M-types. Increased intrinsic virulence has been reported in Streptococcus pyogenes of certain M-types, notably M1 and M3. In the Netherlands these M-types have been independently associated with fatality. Over the last 50 years the genome of these M-types appears to have become enriched with phage-encoded virulence factors, possibly contributing to the altered epidemiology of invasive GAS disease. Despite this genetic plasticity, GAS have remained uniformly susceptible to penicillin. In-vitro studies have shown that the administration of immunoglobulin G can have a neutralising effect in cases ofTSS but clinical studies have failed to provide any statistical support for this.