Odd knowledge

A University of Arizona group seeded household and public toilets in the United States with MS2, a stand-in for viruses shed in stool, and flushed. Contamination of the restroom surfaces they sampled did not depend on whether the lid was up or down. In that seeded test, the underside of the seat averaged more than 10 million plaque-forming units per 100 square centimeters, which is the load they created, not a count from ordinary bathrooms. Compared with brushing and no product, a hydrochloric-acid bowl cleaner cut virus in the bowl water by more than 99.99 percent and on the brush by 97.64 percent, with no significant drop on the seat, rim, floor, lid, or brush holder.

Fourteen used kitchen sponges from homes near Villingen-Schwenningen, Germany, were sequenced and checked under a confocal microscope. Bacteria ran through the sponge, and the densest patches reached 5.4 × 10¹⁰ cells per cubic centimeter, a local figure rather than an average for the whole sponge. Sponges whose owners said they sanitized them regularly, by microwave or hot soapy water, did not contain fewer bacteria than sponges left alone, and close relatives of Moraxella osloensis and Chryseobacterium hominis made up a larger share of the sanitized ones. The authors suggested replacing sponges often, with a week offered as an example, because this was not a controlled test of those methods.

Watermelon, bread, buttered bread, and gummy candy were dropped onto stainless steel, ceramic tile, wood, and carpet inoculated with Enterobacter aerogenes and dried for five hours. Some bacteria transferred in less than one second. Longer contact raised the transfer, but the food and the surface mattered as much or more: more bacteria moved to watermelon than to the other foods, and carpet gave up less than tile or steel. The five-second rule is a slope with a head start, not a safe window.

Twenty-one vacuum cleaners were measured for particles and bacteria leaving the machine. Bacterial emissions ran from 0 to 740,000 per minute. Fine particles, PM2.5, ran from 0.24 to 5,400 micrograms per minute. Price, age, the dust bag, and an exhaust filter did not explain most of that spread.

Forty-five showerheads from nine U.S. cities were swabbed on the inside. Microscopy showed microbes clumped in a biofilm, and in municipal water the nontuberculous mycobacterial sequences were enriched more than 100-fold above the supply water. Those mycobacterial sequences appeared in the municipal systems they sampled, not in the untreated well-water heads. Mycobacterium avium sequences were in 20 percent of swabs and, when present, averaged 32 percent of that swab’s sequence library.

Enterococci and fecal coliforms were measured inside one New York City institutional building, on occupants’ shoe soles, and in sidewalk puddles outside. Mean enterococci were highest in the busy entryway, and counts were significantly higher on carpet than on the uncarpeted floor next to it. Pooled rainwater on those sidewalks averaged 31,000 enterococci per 100 milliliters. It is one building, not a national average.

A hospital ward and an operating theatre were scored by eye, by bacterial culture, and by ATP, a test for organic residue. Of the sites monitored after routine cleaning, 18 percent looked unacceptable, 70 percent failed the microbiological limit the authors used, and 76 percent failed the ATP limit. Overall, general bacterial counts and ATP were not significantly different before and after that clean. The routine under study did not include a biocide.

Twenty-four hospital rooms were cleaned in each setup. With a detergent, the microfiber system removed about 95 percent of the bacteria they plated, and a cotton-string mop removed about 68 percent. A quaternary ammonium disinfectant brought the cotton mop to about 95 percent and did not significantly change the microfiber system. The result belongs to that floor trial, not to every cloth sold for a home.