Antibiotic resistance is a significant threat to public health. Carbapenem-resistant gram-negative bacteria are “priority pathogens” according to the World Health Organization.
In this systematic review from the Pan American Health Organization (PAHO)  we found that the implementation of active surveillance strategies to detect these bacteria can induce a decline in infection or colonization rates. However, the observed effect could be substantially different from the real effect, since studies reported that active surveillance cultures were implemented as part of a bundle intervention, which precludes determining the independent effect.
Resistance to carbapenem antibiotics in gram-negative bacteria has been increasing due to the proliferation of different resistance mechanisms, resulting in a serious public health threat of international concern due to the current absence of effective therapeutic alternatives, which translates into a mortality rate between 34% to 70% [2,3].
The World Health Organization published in 2019 the first ever global guidelines for the prevention and control of carbapenem-resistant Enterobacteriaceae, Acinetobacter baumannii and Pseudomonas aeruginosa in health care facilities  which includes recommendations on surveillance policies.
In order to assist evidence-based decision-making on the effect of surveillance strategies in health care facilities, the Antimicrobial Resistance Special Program, Communicable Diseases and Environmental Determinants of Health from PAHO led a systematic review conducted by the Methodology Team of Epistemonikos Foundation . Existing evidence may favor the use of surveillance culture to carbapenem-resistant gram-negative bacteria, which results in a decline in the prevalence of both infection and colonization rates. But at the same time, some studies suggest screening strategies may result in little to no difference in the risk of all-cause mortality and the length of hospital stay.
Authors warn that the certainty of the evidence was assessed as low, mainly due to serious risk of bias of the included studies and the presence of co-interventions since active surveillance cultures were implemented as part of a bundle intervention which precludes determining the independent effect of active surveillance in these studies. Well-conducted randomized trials or high-quality quasi-experimental studies are needed to improve the certainty of the existing evidence. Authors add that these studies should assess the effect of the addition of screening strategies as a single intervention and measure clinically important outcomes such as infection, length of hospital stay, and mortality.
 Verdugo-Paiva F, Otaiza F, Roson-Rodríguez P, Rojas-Gomez AM, Galas M, El Omeiri N, Fuentes Y, Rada G, Ramón-Pardo P. Effects of screening strategies to detect carbapenem-resistant gram-negative bacteria: A systematic review. American Journal of Infection Control 2022: 1-8. https://doi.org/10.1016/j.ajic.2022.02.018
 Nordmann P, Poirel L. Epidemiology and Diagnostics of Carbapenem Resistance in Gram-negative Bacteria. Clin Infect Dis. 2019;69(Suppl 7):S521-S528. doi: 10.1093/cid/ciz824.
 Guidelines for the Prevention and Control of Carbapenem-Resistant Enterobacteriaceae, Acinetobacter Baumannii and Pseudomonas Aeruginosa in Health Care Facilities. World Health Organization; 2017. Disponible en: https://www.who.int/publications/i/item/9789241550178