Drug-Resistant Infections More Likely With Devices Than Surgery

Nicola M. Parry, DVM

November 25, 2019

Antibiotic-resistant healthcare-associated infections (HAIs) in adult patients are more likely to arise in association with the use of medical devices than after surgery, according to findings from one of two studies published online November 25 in Infection Control and Hospital Epidemiology.

Using data from the Centers for Disease Control and Prevention's (CDC's) National Healthcare Safety Network (NHSN), the reports provide updated national summaries of pathogens and antimicrobial resistance in adult and pediatric central line–associated bloodstream infections (CLABSIs), catheter-associated urinary tract infections (CAUTIs), ventilator-associated pneumonias (VAPs, also known as PVAPs), and surgical site infections (SSIs).

"Patients with a CLABSI, CAUTI, or PVAP have often been admitted to an inpatient unit for several days prior to the infection, and therefore pathogens contributing to these infections are more likely to have been acquired during a patient's hospitalization, when patients are exposed to antimicrobials and where there is significant transmission pressure for resistant organisms," write Lindsey M. Weiner-Lastinger, MPH, from the CDC, Atlanta, Georgia, and colleagues.

"Alternatively, SSIs are often caused by bacterial contamination from the patient's endogenous skin flora, and thus may be less likely to show nonsusceptibility to antimicrobials."

Both reports by Weiner-Lastinger and colleagues were published in the same issue of the journal.

The NHSN is the most widely used electronic surveillance system in the United States for tracking information about HAIs in US healthcare facilities. In addition to helping experts identify emerging antimicrobial-resistant pathogens, these data can also help guide development of new drugs and of policies aimed at preventing the spread of these pathogens.

These latest two reports provide data for the period 2015 to 2017 from facilities that conducted adult (5626 facilities) and pediatric (2545 facilities) HAI surveillance.

In both studies, most of the facilities were general acute care hospitals.

The most commonly reported pathogens in the adult study were Escherichia coli (18%), Staphylococcus aureus (12%), and Klebsiella spp (9%). In the pediatric study, the most commonly reported pathogens were Staphylococcus aureus (15%), Escherichia coli (12%), and coagulase-negative staphylococci (12%).

Overall, the pathogens associated with device-related infections varied according to the type of both the HAI and facility setting.

For example, in the adult and pediatric studies, CLABSI pathogens were most frequently reported in hospital wards (39.0%) and in neonatal intensive care units (NICUs; 37.0%); CAUTI pathogens were most frequently reported in hospital wards (43.4%) and in pediatric intensive care units (ICUs; 70.0%); and VAP pathogens were most frequently reported in hospital ICUs (32.0%) and in pediatric ICUs (98.5%).

In the adult study, oncology units had a specific pathogen distribution. Escherichia coli (16.5%) was the most commonly reported CLABSI pathogen and was more likely to be reported from oncology units than from non-oncology units, such as hospital ICUs (4.1%) or long-term acute care hospitals (LTACHs; 3.6%).

In contrast, in the pediatric study, Staphylococcus spp (46.1%) were the most commonly reported CLABSI pathogens from NICUs. Enterococcus faecalis was the most commonly reported CLABSI pathogen from pediatric ICUs (14.8%) and was more likely to be reported from there than from other pediatric settings, such as NICUs (8.8%) or oncology units (5.2%).

SSI pathogens also varied according to surgery type. In adult and pediatric patients, most pathogens were reported after abdominal (adult, 54.0%; pediatric, 62.8%) and orthopedic (adult, 23.5%; pediatric, 13.8%) surgeries.

For all SSIs among adult and pediatric patients, Staphylococcus aureus was the most commonly reported pathogen (adult, 17.5%; pediatric, 17.6%) and was the most frequently reported one among orthopedic (adult, 38.6%; and pediatric, 32.2%) and cardiac (adult, 27.0%; pediatric, 48.7%) SSIs. Escherichia coli was the most commonly reported pathogen in abdominal SSIs (adult, 19.7%; pediatric, 24.2%).

In the adult study, the percentage of pathogens that were nonsusceptible (%NS) to selected antimicrobial agents varied according to wound closure technique for SSIs after abdominal surgeries. For all pathogens, %NS was greater among non–primarily closed procedures than among primarily closed ones.

In addition, %NS was significantly greater among device-associated HAIs in adults than among SSIs. For example, among Staphylococcus aureus bacteria that were isolated from infections, 48.4% of those tested from device-associated infections were methicillin resistant, compared with 41.9% among those from SSIs.

This difference in resistance was most noticeable among Enterococcus faecium bacteria that were resistant to vancomycin (82.1% from device-associated HAIs vs 55.6% from SSIs).

The data from the adult study also showed that %NS was higher for pathogens from LTACHs than for those from general hospital wards. For example, 23.1% of Klebsiella spp in LTACHs were carbapenem resistant, compared with just 7.2% in the general wards.

In contrast, antimicrobial nonsusceptibility was generally less prevalent in pediatric HAIs than in adult HAIs.

Overall, these findings can provide targets for antimicrobial stewardship programs to help reduce HAIs.

"Aggressive support from public health is necessary to reduce the spread of resistant organisms in healthcare settings, particularly those with high acuity patients and longer lengths of stay, such as hospital ICUs and LTACHs," conclude Weiner-Lastinger and colleagues.

Because of some of the differences in findings between the two studies, they advise facilities to examine local pathogen and drug resistance data related to pediatric patients to help guide efforts to reduce transmission of resistant organisms.

The NHSN surveillance system is supported by the Division of Healthcare Quality Promotion, CDC. The authors have disclosed no relevant financial relationships.

Infect Control Hosp Epidemiol. Published online November 25, 2019. Adult study, Abstract; Pediatric study, Abstract

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