The human impact of commercial delivery cycling injuries: a pilot retrospective cohort study.

BACKGROUND: Commercial delivery cyclists represent a uniquely vulnerable and poorly understood road user. The primary aim of this study was to pilot whether cycling injuries could be categorised as either commercial or non-commercial using documentation entered into routine hospital medical records, in order to determine the feasibility of conducting a large cohort study of commercial cycling injuries in the future. A secondary aim was to determine which key demographic, incident and injury characteristics were associated with commercial versus non-commercial cycling injuries in emergency. METHODS: Pilot retrospective cohort study of adults presenting to an acute public hospital emergency department between May 2019 and April 2020 after sustaining a cycling-related injury. Multinomial logistic regression was used to examine the demographic, incident and injury characteristics associated with commercial compared to non-commercial cycling. RESULTS: Of the 368 people presenting to the emergency department with a cycling-related injury, we were able to categorise 43 (11.7%) as commercial delivery cyclists, 153 (41.6%) as non-commercial cyclists and the working status of 172 (46.7%) was unable to be confirmed. Both commercial and unconfirmed cyclists were more likely to be younger than non-commercial cyclists. Compared to non-commercial cyclists, commercial cyclists were 11 times more likely to speak a language other than English (AOR 11.3; 95% CI 4.07-31.30; p<0.001), less likely to be injured from non-collision incidents than vehicle collisions (AOR 0.36; 95% CI 0.15-0.91; p=0.030) and were over 13 times more likely to present to the emergency department between 8.00pm and 12.00am compared to the early morning hours (12.00 to 8.00am) (AOR 13.43; 95% CI 2.20-82.10; p=0.005). CONCLUSIONS: The growth of commercial cycling, particularly through online food delivery services, has raised concern regarding commercial cyclist safety. Improvements in the recording of cycling injury commercial status is required to enable ongoing surveillance of commercial cyclist injuries and establish the extent and risk factors associated with commercial cycling.

Shifts of live bacterial community in secondary effluent by chlorine disinfection revealed by Miseq high-throughput sequencing combined with propidium monoazide treatment.

Chlorine disinfection is a commonly used disinfection process in wastewater treatment, but its effects on the indigenous bacterial community in treated wastewater have not been fully elucidated. In this study, secondary effluent samples collected in four wastewater treatment plants (WWTPs) were selected for chlorine disinfection. Shifts in the bacterial community compositions in secondary effluent samples upon chlorine disinfection, both immediately and after 24 h of storage, were investigated using Illumina MiSeq sequencing combined with propidium monoazide (PMA) treatment. The results showed that the phylum Proteobacteria was sensitive to chlorine, with the relative proportions of Proteobacteria decreased from 39.2 to 75.9 % in secondary effluent samples to 7.5 to 62.2 % immediately after chlorine disinfection. The phylogenetic analysis indicated that the most dominant genera belonging to Proteobacteria were sensitive to chlorine. In contrast, the phyla Firmicutes and Planctomycetes showed a certain resistance to chlorine, with their relative proportions increasing from 5.1 to 23.1 % and 0.8 to 9.3 % to 11.3 to 44.6 % and 1.5 to 13.3 %, respectively. Most dominant genera belonging to Firmicutes showed resistance to chlorine. A significant reduction in the richness and diversity of the bacterial community was observed after 24 h of storage of chlorinated secondary effluent. During the 24-h storage process, the relative proportions of most dominant phyla shifted in reverse from the changes induced by chlorine disinfection. Overall, chlorine disinfection not only changes the bacterial community compositions immediately after the disinfection process but also exerts further impacts over a longer period (24 h).

UV light tolerance and reactivation potential of tetracycline-resistant bacteria from secondary effluents of a wastewater treatment plant.

Tetracycline-resistant bacteria (TRB) are of concern as emerging microbial contaminants in reclaimed water. To understand the effects of UV disinfection on TRB, both inactivation and reactivation profiles of TRB, as well as 16 tetracycline-resistant isolates from secondary effluent, were characterized in this study. The inactivation ratio of TRB was significantly lower (3.0-log) than that of heterotrophic bacteria (>4.0-log) in the secondary effluent. Additionally, the proportion of TRB significantly increased from 1.65% to 15.51% under 20mJ/cm(2) ultraviolet (UV) exposure. The inactivation rates of tetracycline-resistant isolates ranged from 0.57/s to 1.04/s, of which tetracycline-resistant Enterobacter-1 was the most tolerant to UV light. The reactivation of TRB, tetracycline-resistant isolated strains, as well as heterotrophic bacteria commonly occurred in the secondary effluent even after 20mJ/cm(2) UV exposure. The colony forming ability of TRB and heterotrophic bacteria reached 3.2-log and 3.0-log under 20mJ/cm(2) UV exposure after 22hr incubation. The final inactivation ratio of tetracycline-resistant Enterobacter-1 was 1.18-log under 20mJ/cm(2) UV exposure after 22hr incubation, which is similar to those of TRB (1.18-log) and heterotrophic bacteria (1.19-log). The increased proportion of TRB and the reactivation of tetracycline-resistant enterobacteria in reclaimed water could induce a microbial health risk during wastewater reuse.

Prevalence of antibiotic-resistant bacteria in a lake for the storage of reclaimed water before and after usage as cooling water.

Wastewater reclamation and reuse is a promising way to relieve water scarcity by substituting for natural water consumption by industrial cooling. However, health concerns regarding cooling water originating from reclaimed water are increasing because an abundance of antibiotic-resistant bacteria (ARB) has been detected in reclaimed water. To assess the potential increase of ARB risks in reclaimed water after reuse for industrial cooling, the prevalence of six types of ARB was investigated in water and sediment samples from Lake Gaobeidian, which serves as an artificial circular storage reservoir for reclaimed water for cooling reuse. The effect of treated wastewater and cooling water drainage on the ARB distribution in water and sediment samples was also studied. The results showed that the concentration levels of six types of ARB in lake water samples were as high as those in treated wastewater. The annual median concentrations of total heterotrophic bacteria (HPC) and ARB in discharged cooling water after usage were 0.6-log and 0.4-log higher than those in treated wastewater and the cooling water intake site, respectively, indicating that the process of cooling water usage enhanced the proliferation of HPC and consequently increased the concentrations of ARB. Furthermore, the percentages of penicillin-, ampicillin-, and cephalothin-resistant bacteria in water were 30-57%, 36-48%, and 23-40% higher than those in sediment, respectively. However, the proportions of chloramphenicol-resistant bacteria in water were 35-85% lower than those in sediment. Quantitative evaluation of antibiotic resistance showed that HPC in water had a significant tolerance to penicillin and chloramphenicol, with 50% inhibitory concentrations reaching 22.90 mg L(-1) and 29.11 mg L(-1), respectively.

[Inactivation and reactivation of antibiotic-resistant bacteria during and after UV disinfection in reclaimed water].

Prevalence of antibiotic-resistant bacteria in wastewater effluents is concerned as an emerging contaminant. To estimate inactivation and reactivation potentials of antibiotic-resistant bacteria by UV disinfection, inactivation and reactivation of penicillin-, ampicillin-, cephalexin-, chloramphenicol-and rifampicin-resistant bacteria in the secondary effluent were studied under different UV doses. The results showed that the inactivation ratios of penicillin-, ampicillin-, cephalexin-and chloramphenicol-resistant bacteria were higher than 4-log, which was closed to that of total heterotrophic bacteria; however, the inactivation ratio of rifampicin-resistant bacteria was lower (3.7-log) under 20 mJ x cm(-2) UV exposure. After 22 h standing incubation, antibiotic-resistant bacteria widely reactivated. The colony forming ability of antibiotic-resistant bacteria was as high as 3-log when exposed to 20 mJ x cm(-2) UV light. Hence, conventional UV dose can not effectively control reactivation of antibiotic-resistant bacteria in reclaimed water by UV disinfection.

Inactivation and regrowth of antibiotic-resistant bacteria by PAA disinfection in the secondary effluent of a municipal wastewater treatment plant.

Inactivation and microbial regrowth of penicillin-, ampicillin-, cefalexin-, tetracycline-, chloramphenicol-, and rifampicin-resistant bacteria were studied to explore risks associated with selection and regrowth of antibiotic-resistant bacteria after PAA disinfection. The results showed that after exposure to 20 mg/L PAA for 10 min, inactivation of ampicillin-resistant bacteria reached 2.3-log, which was significantly higher than that of total heterotrophic bacteria with a decrease of 2.0-log. In contrast, inactivation of tetracycline- resistant bacteria was significantly less efficient, reaching only 1.1-log. Chloramphenicol-and tetracycline-resistant bacteria, as well as total heterotrophic bacteria regrew more than 10 fold compared to those in the untreated wastewater sample with 22 h stilling culture after exposure to 2 or 5 mg/L PAA as for 10 min. Selection and potential regrowth of tetracycline-and chloramphenicol-resistant bacteria are potential risks when utilizing PAA disinfection, which may induce the spread of specific antibiotic-resistant bacteria in reclaimed water.