The MRSA strain, called t016-ST22-MRSA-IV, has a unique pattern of antibiotic resistance; it could resist at least four drugs, including flucloxacillin, ciprofloxacin, gentamicin, and trimethoprim. Fortunately, there were others to which it was still susceptible, including clindamycin, tetracycline, fusidic acid, co-trimoxazole, and linezolid.

MRSA most often plagues healthcare settings, but it’s also known to spread in communities, such as in this case. So-called community-associated MRSA is often linked to crowded settings where people have close contact, such as sports activities, daycares, and prisons. The outbreak reported here was not only the largest MRSA outbreak ever recorded in Ireland, it was also the first known outbreak anywhere to be linked to bouncy castle use. The connection became more understandable during the official investigation.

Ideal conditions

After interviewing the families of the infected children, officials learned that most of the children played in the bouncy castles for multiple hours—some as long as five, six, or more hours. Inside, it was crowded, and the children’s play was described as “rough-and-tumble” (as parents would likely expect). Such play could have caused superficial abrasions and scrapes, offering the bacterium an opening. Parents also recalled that the weather that day was humid, warm, and rainy. Many of the children were noticeably wet. In all, these conditions could have been ideal for an MRSA strain to flourish and spread.

Of the 48 children infected, 47 played in the bouncy castles. The one child who had not been in the inflatable structure had very close contact with an exposed child shortly afterward. In all, officials concluded that no other exposure appeared as a plausible explanation for the outbreak; everything pointed to the bouncy castles. Still, they decided against trying to swab them for the MRSA strain. For one thing, a positive surface swab still wouldn’t confirm the castle was the source. Moreover, by the time officials had suspected the castles, they questioned whether MRSA would still be alive on surfaces, let alone how much of the surface of the three castles they would have to swab to find any. Instead, the health officials contacted the bouncy castle owners and advised them to do a thorough decontamination.