Risk Factors Identified in Patient-to-Patient Transmission of Resistant Bacteria

New research could help identify at-risk individuals

Three key factors increase the risk for patient-to-patient transmission of extremely drug-resistant bacteria known as carbapenem-resistant enterobacteriaceae (CP-CRE), according to a new study published in Infection Control & Hospital Epidemiology. The research helps explain why some contacts of an infected patient acquire the dangerous bacteria while others do not.

“The spread of CP-CRE is a major public health concern because it is extremely drug resistant; however, the research on these pathogens is very limited, and so is our knowledge of their transmission,” said lead author Vered Schechner, MD, MSc, an infection-control physician at Tel Aviv Sourasky Medical Center in Israel. “Identifying high-risk groups helps us to avoid excessive screening that can be risky and expensive, and to determine who should be screened and who might be a candidate for pre-emptive isolation or antibiotics.”

CP-CRE infections often occur in patients in hospitals, nursing homes, and other health care settings who require devices such as ventilators and catheters, and in those who are receiving long courses of certain antibiotics. Comparing infected patients with those showing no signs of CP-CRE, the researchers found that 96% of patient-to-patient transmissions had at least one identified risk factor:

  • Contact for more than three days with the infected individual;
  • Mechanical ventilation; or
  • Infection with another multidrug-resistant organism.

In addition, the researchers found that patients who had taken cephalosporin antibiotics were less likely to acquire a CP-CRE infection from another patient than were those administered other antibiotics. Since antibiotic use is a risk factor for acquiring antibiotic-resistant organisms, it appears that cephalosporins might reduce the risk for CP-CRE compared with other drugs, according to the authors. However, there was no protective effect of cephalosporins when compared with patients receiving no antibiotics, and the researchers said that further investigation is needed.

The new study was based on data from 3,158 adult inpatients who were screened for CP-CRE because of contact with another patient diagnosed with the pathogen between October 2008 and June 2012. In total, 53 patients were positive for CP-CRE and served as the case group, along with a group of 106 who had screened negative for CP-CRE.

Sources: SHEA; July 25, 2016; and ICHE; July 25, 2016.