The Effect of Antibiotic Restriction Programs on Prevalence of Antimicrobial Resistance: A Systematic Review and Meta-Analysis

Background In hospital settings, restriction of selected classes of antibiotics is usually believed to contribute to containment of resistance development. We performed a systematic review and meta-analysis to assess the effect of restricting the use of specific antibiotic classes on the prevalence of resistant bacterial pathogens. Methods We conducted a systematic literature search in Embase and PubMed/OVID MEDLINE. We included studies until June 4, 2020 in which a restrictive antibiotic policy was applied and prevalence of resistance and use of antibiotics were reported. We calculated the overall effect of antimicrobial resistance between postintervention versus preintervention periods using pooled odds ratios (ORs) from a mixed-effects model. We stratified meta-analysis by antibiotic-pathogen combinations. We assessed heterogeneity between studies using the I2 statistic and sources of heterogeneity using meta-regression. Results We included 15 individual studies with an overall low quality of evidence. In meta-analysis, significant reductions in resistance were only observed with nonfermenters after restricting fluoroquinolones (OR = 0.77, 95% confidence interval [CI] = 0.62–0.97) and piperacillin-tazobactam (OR = 0.81, 95% CI = 0.72–0.92). High degrees of heterogeneity were observed with studies restricting carbapenem (Enterobacterales, I2 = 70.8%; nonfermenters, I2 = 81.9%), third-generation cephalosporins (nonfermenters, I2 = 63.3%), and fluoroquiolones (nonfermenters, I2 = 64.0%). Results were comparable when excluding studies with fewer than 50 bacteria. There was no evidence of publication bias for any of the antibiotic-pathogen combinations. Conclusions We could not confirm that restricting carbapenems or third-generation cephalosporins leads to decrease in prevalence of antibiotic resistance among Enterobacterales, nonfermenters, or Gram-positive bacteria in hospitalized patients. Nevertheless, reducing fluoroquinolone and piperacilline-tazobactam use may decrease resistance in nonfermenters.

A Pivotal Role of Reactive Oxygen Species in Non-Host Resistance Mechanisms in Legume and Cereal Plants to the Incompatible Pathogens

Most of plants under normal conditions are resistant to most of the incompatible pathogens (viral, fungal and bacterial infections). This is called ״non-host resistance (NHR) phenomenon״. Till now it is not clear the non-host resistance mechanisms. As a result of inoculation of legume (pea and soybean) and cereal (barley and wheat) plants with compatible and incompatible pathogens, strong resistance symptoms were observed in the non-host/incompatible pathogen combinations as compared with host/compatible pathogen combinations which showed severe infection (susceptibility). Levels of reactive oxygen species (ROS) mainly hydrogen peroxide (H2O2) and superoxide (O2.-) were significantly increased early 6, 12, 24 and 36 hours after inoculation (hai) in the non-host plants as compared with host plants. Interestingly enough that the activities of the antioxidant enzymes such as catalase (CAT), dehydroascorbate reductase (DHAR) and peroxidase (POX) were not significantly increased at the same early time 6 - 36 hai in the non-host plants. However, these enzymes were significantly increased later on 48, 72 and 96 dai in the non-host plants as compared with host plants. It seems that early accumulation of H2O2 and O2.- could have a dual roles, first role is inhibiting or killing the pathogens early in the non-host plants, second immunization of the non-host plants by stimulating the activities of the antioxidant enzymes later on which thereby, neutralize the harmful effect of ROS and consequently suppressing disease symptoms. The author recommends giving more attention to these new mechanisms of non-host resistance particularly in relation to ROS levels and antioxidant activities which are very important for plant breeders and useful for finding alternative control strategies as well.

Antimicrobial resistance in eight US hospitals along the US–Mexico border, 2000–2006

SUMMARYAntimicrobial resistance (AR) is a growing problem worldwide and international travel, cross-border migration, and antimicrobial use may contribute to the introduction or emergence of AR. We examined AR rates and trends along the US–Mexico border by analysing microbiology data from eight US hospitals in three states bordering Mexico. Microbiology data were ascertained for the years 2000–2006 and for select healthcare and community pathogens including, three Gram-negative (Escherichia coli, Pseudomonas aeruginosa, Klebsiella pneumoniae) and three Gram-positive (Staphylococcus aureus, Enterococcus, Streptococcus pneumoniae) pathogens and 10 antimicrobial–pathogen combinations. Resistance was highest in S. aureus (oxacillin resistance 45·7%), P. aeruginosa (quinolone resistance 22·3%), and E. coli (quinolone resistance 15·6%); six (60%) of the 10 antimicrobial–pathogen combinations studied had a significantly increasing trend in resistance over the study period. Potential contributing factors in the hospital and community such as infection control practices and antimicrobial use (prescription and non-prescription) should be explored further in the US–Mexico border region.