Group A Streptococcus Carriage among Close Contacts of Patients with Invasive Infections

Abstract

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 Hôpital 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.

Group A streptococcus in the gynecologic patient

“…4,5 The reason for this trend is not entirely clear. It is possible that the availability of newer antibiotics has decreased the incidence of GAS infections in childhood but has created a population of adults who may be more susceptible to GAS infections due to lack of exposure as children.…”

“…Recently, there have been reports that the incidence of GAS infections is increasing again. 4,5 We want to report two recent cases of peritonitis resulting from GAS infections in gynecologic patients. These women were seriously ill; most of the clinicians caring for these women were not aware of the possibility of GAS infection, for this type of infection had not been seen in our practice for over a decade.…”

QUESTION 1: Are household contacts of patients with invasive group A streptococcal disease at higher risk of secondary infection?

“…Secondary cases of invasive GAS disease in the contacts of index cases are reported in the peripartum period, nosocomial or institutional settings, households and in community clusters, such as schools 6 9. Close household contacts are generally defined as persons that have spent at least 24 h with the index case or have spent 50% of nights in the house during the week preceding the onset of invasive GAS disease 2 5 10. The risk of invasive GAS disease in close household contacts is highest in the first 30 days after the onset in the index case, with most secondary cases occurring in the first week and few cases beyond 1 month 1–3 5 9…”

Necrotizing fasciitis: The importance of early diagnosis, prompt surgical debridement and adjuvant therapy

“…Recurrent cases of NF are uncommon with only few case reports including MRSA and a case of complement C4 deficiency where GAS NF was succeeded by streptococcal pneumonia NF [31,98] Antimicrobial Prophylaxis for Contacts of GAS NF This is a controversial issue despite the recognition that sporadic secondary cases of iGAS (infective GAS infection) occurred following close contact with an index case of GAS NF [2]. Around 27% of household contacts are reported to be GAS carriers [77,99]. The secondary iGAS cases within the household of an index case are reported to be 200 times more likely to occur (294 per 100,000 contacts), but international guidelines on prophylaxis vary widely in their recommendation [11].…”