A 3-month outbreak of invasive group A Streptococcus disease at an eldercare facility, in which 5 persons died, was biphasic. Although targeted chemoprophylaxis contained the initial outbreak, a second phase of the outbreak occurred after infection control processes ended. To retrospectively investigate the genomic epidemiology of the biphasic outbreak, we used whole-genome sequencing and multiple bioinformatics approaches. Analysis of isolates from the outbreak and isolates prospectively collected during the outbreak response indicated a single S. pyogenes emm81 clone among residents and staff members. Outbreak isolates differed from nonoutbreak emm81 isolates by harboring an integrative conjugative genomic element that contained the macrolide resistance determinant erm(TR). This study shows how retrospective high-resolution genomic investigations identified rapid spread of a closed-facilty clonal outbreak that was controlled, but not readily cleared, by infection control management procedures.

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Biphasic Outbreak of Invasive Group A Streptococcus Disease in Eldercare Facility, New Zealand.

BackgroundPublic health guidance recommending isolation of individuals with group A streptococcal (GAS) infection or carriage for 12-24 h from antibiotic initiation to prevent onward transmission requires a strong evidence base.AimTo estimate the pooled proportion of individuals who remain GAS culture-positive at set intervals after initiation of antibiotics through a systematic literature review (PROSPERO CRD42021290364) and meta-analysis.MethodsWe searched Ovid MEDLINE (1946-), EMBASE (1974-) and Cochrane library. We included interventional or observational studies with ≥ 10 participants reporting rates of GAS throat culture positivity during antibiotic treatment for culture-confirmed GAS pharyngitis, scarlet fever and asymptomatic pharyngeal GAS carriage. We did not apply age, language or geographical restrictions.ResultsOf 5,058 unique records, 43 were included (37 randomised controlled studies, three non-randomised controlled trials and three before-and-after studies). The proportion of individuals remaining culture-positive on day 1, day 2 and days 3-9 were 6.9% (95% CI: 2.7-16.8%), 5.4% (95% CI: 2.1-13.3%) and 2.6% (95% CI: 1.6-4.2%). For penicillins and cephalosporins, day 1 positivity was 6.5% (95% CI: 2.5-16.1%) and 1.6% (95% CI: 0.04-42.9%), respectively. Overall, for 9.1% (95% CI: 7.3-11.3), throat swabs collected after completion of therapy were GAS culture-positive. Only six studies had low risk of bias.ConclusionsOur review provides evidence that antibiotics for pharyngeal GAS achieve a high rate of culture conversion within 24 h but highlights the need for further research given methodological limitations of published studies and imprecision of pooled estimates. Further evidence is needed for non-beta-lactam antibiotics and asymptomatic individuals. 

https://www.eurosurveillance.org/deliver/fulltext/eurosurveillance/28/15/eurosurv-28-15-4.pdf?itemId=%2Fcontent%2F10.2807%2F1560-7917.ES.2023.28.15.2200573&mimeType=pdf&containerItemId=content/eurosurveillance

Time to negative throat culture following initiation of antibiotics for pharyngeal group A Streptococcus: a systematic review and meta-analysis up to October 2021 to inform public health control measures

We report a group B streptococcus (GBS) necrotizing soft tissue infection (NSTI) without apparent portal of entry, with pharyngeal and perineal carriage of the same strain. A 49-year-old man with uncontrolled type 2 diabetes mellitus (HbA1c 12%) was referred to our hospital for febrile painful erythematous and swelling left leg with a necrotic and hypoesthetic area (Figure 1). NSTI was suspected. The recent history revealed an intake of non-steroidal anti-inflammatory drugs (NSAIDs; ibuprofen) 3 days earlier.

Group B streptococcal necrotizing soft‐tissue infection: role of pharyngeal and perineal carriage

Background: Public health guidance recommending isolation of individuals with group A streptococcal (GAS) infection or carriage for 12-24 hours from antibiotic initiation to prevent onward transmission requires a strong evidence-base. Methods: We conducted a systematic review (PROSPERO CRD42021290364) and meta-analysis to estimate the pooled proportion of individuals who remain GAS culture-positive at set intervals after initiation of antibiotics. We searched Ovid MEDLINE (1946-), EMBASE (1974-) and the Cochrane library. We included interventional or observational studies with ten or more participants reporting rates of GAS throat culture during antibiotics for culture confirmed GAS pharyngitis, scarlet fever, and asymptomatic pharyngeal GAS carriage. We did not apply age, language, or geographical restrictions. Findings: Of 5,058 unique records identified, 43 were included; 37 (86%) randomised controlled studies, three (7%) non-randomised controlled trials and three (7%) before-and-after studies. The proportion of individuals who remained culture-positive at day 1, day 2, and day 3-9 were 6.9% (95% CI 2.7-16.8%), 5.4% (95% CI 2.1-13.3%) and 2.6% (95% CI 1.6-4.2%). For penicillins and cephalosporins, day 1 positivity was 6.5% (95% CI 2.5-16.1%) and 1.6% (95% CI 0.04-42.9%) respectively. Overall, for 9.1% (95% CI 7.3-11.3), throat swabs collected after completion of therapy were GAS culture-positive. Interpretation: Our review provides evidence that antibiotics for pharyngeal GAS achieve a high rate of culture conversion within 24 hours but highlights the need for further research given the methodological limitations of published studies and imprecision of pooled estimates. Further evidence is needed for non-beta-lactam antibiotics and for asymptomatic individuals.

Time to negative throat culture following initiation of antibiotics for pharyngeal group A Streptococcus: a systematic review and meta-analysis to inform public health control measures

Background Public health guidance recommending isolation of individuals with group A streptococcal (GAS) infection or carriage for 12–24 h from antibiotic initiation to prevent onward transmission requires a strong evidence base. Aim To estimate the pooled proportion of individuals who remain GAS culture-positive at set intervals after initiation of antibiotics through a systematic literature review (PROSPERO CRD42021290364) and meta-analysis. Methods We searched Ovid MEDLINE (1946–), EMBASE (1974–) and Cochrane library. We included interventional or observational studies with ≥ 10 participants reporting rates of GAS throat culture positivity during antibiotic treatment for culture-confirmed GAS pharyngitis, scarlet fever and asymptomatic pharyngeal GAS carriage. We did not apply age, language or geographical restrictions. Results Of 5,058 unique records, 43 were included (37 randomised controlled studies, three non-randomised controlled trials and three before-and-after studies). The proportion of individuals remaining culture-positive on day 1, day 2 and days 3–9 were 6.9% (95% CI: 2.7–16.8%), 5.4% (95% CI: 2.1–13.3%) and 2.6% (95% CI: 1.6–4.2%). For penicillins and cephalosporins, day 1 positivity was 6.5% (95% CI: 2.5–16.1%) and 1.6% (95% CI: 0.04–42.9%), respectively. Overall, for 9.1% (95% CI: 7.3–11.3), throat swabs collected after completion of therapy were GAS culture-positive. Only six studies had low risk of bias. Conclusions Our review provides evidence that antibiotics for pharyngeal GAS achieve a high rate of culture conversion within 24 h but highlights the need for further research given methodological limitations of published studies and imprecision of pooled estimates. Further evidence is needed for non-beta-lactam antibiotics and asymptomatic individuals.

Using population-based surveillance data, we quantified the secondary invasive group A Streptococcus disease risk among household contacts. The disease risk in the 30 days postexposure to an index-case patient was highest among individuals aged ≥65 years, versus the annual background incidence of all ages.

Austin Bell

Papers

Evaluating Household Transmission of Invasive Group A Streptococcus Disease in the United States Using Population-based Surveillance Data, 2013–2016