CHICAGO, Sept. 18 (Xinhua) -- Mankind faces the risk of attack from superbug bacteria consisting of more than one kind of bacteria, and trying different antibiotics to control one such "superbug" may only encourage others lurking nearby, new findings of a study of the University of Michigan (UM) show.
UM researchers used detailed data from a long-term study of nursing home patients. Nearly two-thirds of the patients studied were treated with one or more of 50 different antibiotics during the study period. All the patients in the study used a urinary catheter to empty their bladders for at least three days during the study period, allowing researchers to look at patterns of urinary tract infections, which in nursing home and hospital patients often arise from bacteria entering the bladder along a catheter.
The findings showed that colonization of such patients' skin, noses and throats with common MDROs was not random.
"We observed a complex network of interactions, with acquisition of each of six different multidrug-resistant organism (MDRO) species being influenced by different sets of antibiotics, and primary MDRO colonization in turn increasing the risk of acquisition and infection by other MDROs," said lead author Joyce Wang, a postdoctoral fellow at UM Medical School Department of Microbiology and Immunology.
Colonization with one MDRO increased the risk of acquiring other MDROs. And treatment of a patient with any given antibiotic increased their chances of being colonized with an MDRO, which in turn altered their risk of becoming colonized with another MDRO later.
To be specific, 40 percent of the 234 frail elderly patients in the study had more than one MDROs living on their bodies. Patients who had specific pairs of MDROs were more likely to develop a urinary tract infection involving an MDRO.
UM researchers have focused on two of the most dangerous MDROs, vancomycin resistant Enterococcus (VRE) and methicillin-resistant Staphylococcus aureus (MRSA), as well as four Gram-negative bacteria that have evolved resistance to two powerful antibiotics.
"We need to understand what clinical practices drive the spread of MDROs in health care facilities, and counterintuitively, it appears that a key factor is the use of certain antibiotics against an individual organism that may impact other circulating organisms," said systems biologist Evan Snitkin at UM Medical School Department of Microbiology and Immunology.
The researchers have created a map of interactions among bacteria and classes of antibiotics, which could help health care providers in choosing to treat a patient with a specific antibiotic. But that will take time, and need more research in the laboratory and in health care facilities, the researchers hold.
UM researchers hope that their findings will give healthcare providers and patients more reason to avoid using antibiotics in the first place unless they are truly necessary.
The findings have been published in the Proceedings of the National Academy of Sciences.
