SAN FRANCISCO — The number of invasive group A streptococcal infections in England is on an upsurge, for reasons that remain unclear.
“The current increases in diseases caused by group A streptococcus [GAS] being seen in some regions of England may be attributable to the natural cycle of the disease, with some 'quiet' years followed by a year of high incidence,” Androulla Efstratiou, Ph.D., said at the annual meeting of the Interscience Conference on Antimicrobial Agents and Chemotherapy. Speaking in an interview after a study about the increase was presented during a poster session, Dr. Efstratiou said that “nonetheless, the Health Protection Agency has been monitoring the situation closely and has launched enhanced surveillance.”
The surveillance includes collecting detailed information on clinical presentations, risk factors, patient outcomes, severity of infection, clustering patterns, and characteristics of the streptococcal strains, said Dr. Efstratiou of the respiratory and systemic infections department at the Health Protection Agency Center for Infections, London. “Information generated from this surveillance may identify new opportunities for preventing the infection, helping clinicians to recognize early signs of the infection and possibly help in the future development of vaccine formulations and clinical guidelines for control, management, and prevention.”
She noted that there is no current evidence of the emergence of a new strain of invasive GAS circulating in England, although an unusual increase in emm3 was observed in the early part of 2009. “This strain is associated with more severe forms of invasive disease, but it's too early to say how significant this strain may be to the overall increase,” she said.
For the study, Dr. Efstratiou and her associates identified 598 invasive GAS infections from isolates submitted to the Health Protection Agency's reference laboratory by hospitals in England between Nov. 1 and March 31, 2008. This represented a 62% increase over the same time period in the previous year. The most common GAS emm types in order of prevalence were emm3, emm89, emm28, and emm6. The number of emm3 cases spiked markedly from 15% in November 2008 to 40% in January 2009.
No atypical patterns of antiomicrobial resistance emerged among the strains; only 3% were resistant to erythromycin.
“Preliminary analysis of enhanced surveillance data found that 30% of cases did not have any underlying illness,” the researchers reported in their poster. “Skin lesions, childbirth, and varicella were the most common acute risk factors.”
Nearly one-quarter of cases (22%) were children younger than age 15 years. Of the 234 cases with outcome information, 22% died within 1 week.
“Clinicians should be mindful of the signs and symptoms of invasive GAS and maintain a high index of suspicion in relevant patients as early recognition and prompt initiation of specific and supportive therapy can be lifesaving,” she said. “The spread of all types of GAS infections may be reduced by use of tissues to help limit the spread of bacteria from coughs and sneezes and thus the potential for spread to others, and by hand washing, especially after coughing and sneezing, and before preparing foods and eating.”
She also emphasized the importance of keeping wounds clean as a way to prevent invasive GAS. Wounds “should be watched for possible signs of infection, which include increasing redness, swelling, and pain at the wound site,” she said. “If these signs occur, especially in a person who also has a fever, they should consult their [physician] immediately.”
Dr. Efstratiou said she had no conflicts to disclose.