Molecular characterization of clinical isolates of M non-typable group A streptococci from invasive disease cases

Burden of group A streptococcal meningitis in Salvador, Brazil: report of 11 years of population-based surveillance

BACKGROUND

Over recent decades, a resurgence of invasive group A streptococcal (GAS) infections has been observed; GAS remains a rare cause of pyogenic meningitis. We report herein population-based findings of long-term surveillance for GAS meningitis in Salvador, Brazil, and estimate the overall burden of invasive GAS infections.

METHODS

From February 1996 to February 2007 we conducted active surveillance for GAS meningitis in the state reference hospital for infectious diseases in Salvador, Brazil. Data on clinical presentation, laboratory records, and outcome were collected through interviews and chart review. GAS isolates were evaluated for antimicrobial susceptibility and emm type.

RESULTS

We identified 20 cases of GAS meningitis, which accounted for 0.9% of all culture-proven bacterial meningitis in the study period. The mean annual incidence of GAS meningitis was 0.03 cases per 100,000 population in metropolitan Salvador and peaked in children <1 year of age (0.67 cases per 100,000 population). Among 17 cases with clinical information available, 41% required intensive care unit support and 25% died. Tested isolates were susceptible to penicillin and exhibited large emm type diversity. Based on the incidence of GAS meningitis, we estimate that the annual incidence of GAS infection is 3 cases per 100,000 population in metropolitan Salvador.

CONCLUSIONS

Although rare, GAS is a life-threatening cause of bacterial meningitis. Knowledge of the incidence and emm type variability of the disease is necessary for planning immunization strategies.

Streptococcus pyogenes emmand T types within a decade, 1996–2005: implications for epidemiology and future vaccines

Streptococcus pyogenesgroup A (GAS) is a primary human pathogen. We performed geneticemmsequence and serological T-antigen typing of 819 mostly invasive GAS isolates recovered in Israel during 1996–2005. Of the 72emmtypes found, the six most prevalent types (1, 81, 89, 14, 28, 5) comprised 30·2% of all isolates, andemm-type changes were observed over the years. The predicted coverage of the 26-valentS. pyogenesvaccine formulated for usage in the USA was predicted to be only ~60%. On the basis of differentemm–T antigen type associations, some Israeli strains are probably different clonal types than those found in USA. About 2% of GAS hademmtypes that were originally associated withS. dysgalactiaesubsp.equisimilis emmgenes. Therefore, routineemmtyping allows meaningful GAS strain surveillance, and provides data relevant to better vaccine coverage.

Characterization of emm types and superantigens of Streptococcus pyogenes isolates from children during two sampling periods

The characteristics of 359 group A streptococcal (GAS) isolates collected from Chinese paediatric patients in two periods (1993-1994, 2005-2006) were studied. Isolates were assigned to emm types and assayed for eight superantigen (SAg) genes (speA, speC, speH, speI, speG, speJ, ssa, SMEZ). Types emm1 and emm12 were consistently the most prevalent during the two periods, while others varied in frequency. GAS isolates carrying six or more SAg genes increased from 46.53% (1993-1994) to 78.39% (2005-2006); ssa, speH and speJ genes (P<0.05) increased but speA declined (P<0.05). SAg gene profiles were closely associated with the emm type, but strains of the same emm type sometimes carried different SAg genes in the two periods. No significant difference in emm-type distribution and SAg gene profile was noted between isolates from different diseases. These data may contribute towards the development of a GAS vaccine in China.

Epidemic of severe Streptococcus pyogenes infections in injecting drug users in the UK, 2003-2004

During the late 1990s, increases in referrals to the national reference laboratory of Streptococcus pyogenes isolates from injecting drug users (IDUs) with severe soft tissue infection indicated an emerging problem in the UK, later confirmed during the 2003-2004 European enhanced surveillance (Strep-EURO) programme. In light of these findings, further analyses were undertaken in an attempt to understand the reasons behind this increase in referrals. Single and multivariable analyses were undertaken to compare clinical, microbiological and demographic characteristics of IDUs diagnosed with severe S. pyogenes infection during the 2003-2004 enhanced surveillance study with those of other cases arising during this same period. Temporal and spatial analyses were undertaken for IDUs to identify clustering, as a means of understanding the transmission dynamics underpinning this increase. Infections in IDUs were spread across the UK, with some concentration in northern England and London. IDUs presented with a wide range of clinical manifestations, including pneumonia, which was found to be significantly more common in IDUs (OR 3.00) than in other cases. Marked differences in type distributions were found between IDUs and other cases, in particular the concentration of emm/M83 (22% of IDUs, 2% of non-IDUs). These findings indicate that an epidemic of severe S. pyogenes infections in IDUs occurred in the UK, peaking in 2003. The explanation for this rise remains unclear.

Streptococcal Infections

The streptococci are a large heterogeneous group of gram-positive spherically shaped bacteria widely distributed in nature. They include some of the most important agents of human disease as well as members of the normal human flora. Some streptococci have been associated mainly with disease in animals, while others have been domesticated and used for the culture of buttermilk, yogurt, and certain cheeses. Those known to cause human disease comprise two broad categories: First are the pyogenic streptococci, including the familiar β-hemolytic streptococci and the pneumococcus. These organisms are not generally part of the normal flora but cause acute, often severe, infections in normal hosts. Second are the more diverse enteric and oral streptococci, which are nearly always part of the normal flora and which are more frequently associated with opportunistic infections.

Necrotizing Fasciitis of the Extremities

Necrotizing fasciitis (NF) describes a life threatening soft tissue infection characterized by a rapid spreading infection of the subcutaneous tissue and in particular the fascia. Various synonyms for this type of infection are used, often due to the difficult diagnosis. Necrotizing fasciits of the extremities is found after simple skin lacerations and often in rural, farming or garden setting environments. Many of the infections are found in immunologically healthy people, but persons revealing a compromised wound healing are endangered additionally, e.g., diabetes. In the majority of the microbiological analyses, streptococci alone or a mixture with mainly anaerobic bacteria may be detected. The management of infected extremities requires a rapid diagnosis, dedicated aggressive surgical management as soon as possible, and a wide debridement extending the border of the infected fascia. Timely surgical revisions within the first day or days together with antibiotic treatment are the only measures to stop the infection. Depending on the status of the patient a hyperbaric oxygenation treatment seems to be useful in order to limit the infection. In fulminated cases early amputations, maximal intensive care treatment of the septic patient are required, where all means are warranted to save the patients life. As a consequence, early clinical diagnoses with thorough surgical debridement of the infected liquid necrotic fascia as well as correct antibiotic treatment are needed. Secondary plastic reconstruction of the soft tissue defects will generally be required.

Necrotizing soft tissue infections

PURPOSE OF REVIEW

The purpose of this review is to consider recent advances in the definition, pathogenesis, diagnostic criteria, and treatment of necrotizing soft tissue infections.

RECENT FINDINGS

The efficacy of early surgical debridement combined with antimicrobial therapy, close monitoring and physiologic support is strongly demonstrated. Novel therapeutic strategies including vacuum-assisted wound-closure therapy and intravenous immunoglobulin have been described.

SUMMARY

Necrotizing soft-tissue infection is a rare infection of the subcutaneous tissue and fascia that is often associated with sepsis and can progress rapidly with a possible fatal outcome. Although the cause is not yet understood fully, patients often have a prior history of a small, trivial trauma, wound, or scratch. Establishing the diagnosis can be the main challenge in treating patients, and knowledge of all available tools is key for early and accurate diagnosis.

emm Types, virulence factors, and antibiotic resistance of invasive Streptococcus pyogenes isolates from Italy: What has changed in 11 years?

To investigate the epidemiology and characteristics of invasive group A streptococcal (GAS) disease over 11 years in Italy, this study compared the emm types and the superantigen toxin genes speA and speC as well as the erythromycin, clindamycin, and tetracycline susceptibilities of 207 invasive GAS strains collected during two national enhanced surveillance periods (1994 to 1996 and 2003 to 2005) and the time between each set of surveillance periods. The present study demonstrated that emm1 strains were consistently responsible for about 20% of invasive GAS infections, while variations in the frequencies of the other types were noted, although the causes of most cases of invasive infections were restricted to emm1, emm3, emm4, emm6, emm12, and emm18. During the 1994 to 1996 surveillance period, an emm89 epidemic clone spread across the northern part of Italy. A restricted macrolide resistance phenotype-type distribution of the bacteriophage-encoded speA toxin as well as of macrolide resistance genes was noted over time. Indeed, the recent acquisition of macrolide resistance in previously susceptible emm types was observed.