Risk factors associated with carbapenemase-producing enterobacterales (CPE) positivity in the hospital wastewater environment

Background:Hospital wastewater is an increasingly recognized reservoir for resistant Gramnegative organisms. Factors involved in establishment and persistence of Klebsiella pneumoniae carbapenemase-producing organisms (KPCO) in hospital wastewater plumbing are unclear. Methods: This study was conducted at a hospital with endemic KPCO linked to wastewater reservoirs and robust patient perirectal screening for silent KPCO carriage. Over five months, both rooms occupied and not occupied by KPCO-positive patients were sampled at three wastewater sites within each room (sink drain, sink P-trap, and toilet or hopper). Risk factors for KPCO positivity were assessed using logistic regression. Whole genome sequencing (WGS) identified environmental seeding by KPCO-positive patients. Findings: 219/475(46%) room sampling events were KPCO-positive in at least one wastewater site. KPCO-positive patient exposure was associated with increased risk of environmental positivity for the room and toilet/hopper. Previous positivity and intensive care unit room type were consistently associated with increased risk. Tube feeds were associated with increased risk for the drain, while exposure to patients with Clostridioides difficile was associated with decreased risk. Urinary catheter exposure was associated with increased risk of P-trap positivity. P-trap heaters reduced risk of P-trap and sink drain positivity. WGS identified genomically linked environmental seeding in six of 99 room occupations by 40 KPCO-positive patients. Interpretation: KPCO-positive patients seed the environment in at least 6% of opportunities; once positive for KPCO, wastewater sites are at greater risk of being positive subsequently. Increased nutrient exposure, e.g. due to tube food disposal down sinks, may increase risk; frequent flushing may be protective. IMPORTANCE: Klebsiella pneumoniae carbapenemase-producing organisms (KPCOs) are bacteria that are resistant to most antibiotics and thus are challenging to treat when they cause infections in patients. These organisms can be acquired by patients who are hospitalized for other reasons, complicating their hospital stay and even leading to death. Hospital wastewater sites, such as sink drains and toilets, have played a role in many reported outbreaks over the past decade. The significance of our research is in identifying risk factors for environmental positivity for KPCOs, which will facilitate further work to prevent transmission of these organisms to patients from the hospital environment.</p

Perturbation of formate pathway and NADH pathway acting on the biohydrogen production

Abstract The formate pathway and NADH pathway as two common hydrogen-producing metabolic pathways have been well characterized to understand and improve biohydrogen production. These two pathways have been thought to be separate and have been independently investigated. However, in this study, perturbation of genes (hycA, fdhF, fhlA, ldhA, nuoB, hybO, fdh1, narP, and ppk) in Enterobacter aerogenes related to the formate pathway or NADH pathway revealed that these two pathways affected each other. Further metabolic analysis suggested that a linear relationship existed between the relative change of hydrogen yield in the formate pathway or NADH pathway and the relative change of NADH yield or ATP yield. Thus, this finding provides new insight into the role of cellular reducing power and energy level in the hydrogen metabolism. It also establishes a rationale for improving hydrogen production from a global perspective