Diversity of Multidrug-Resistant Bacteria in an Urbanized River: A Case Study of the Potential Risks from Combined Sewage Overflows

Isolation, identification, and characterization of resistant bacteria to antibiotics from pharmaceutical effluent and study of their antibiotic resistance

Pharmaceutical effluents primarily enter aquatic environments through the discharge of treated and untreated wastewater from various sources, including hospitals, pharmaceutical manufacturing facilities, and households. Microbes sourced from pharmaceutical effluents such as Pseudomonas spp. pose a significant public health concern because of their high levels of resistance to multiple drugs and extreme multidrug resistance. Therefore, the present study was conducted for the isolation, identification, and molecular characterization of selected isolates from pharmaceutical effluents and also determined their antibiotic sensitivity patterns. From June 2016 to March 2017, a study was conducted on four well-known pharmaceutical companies specializing in antibiotic production in Dhaka and Gazipur. Four wastewater samples were collected from various origins and then brought to the Bacteriology laboratory for microbiological examination. Twelve pure isolates were obtained and characterized through cultural and biochemical tests while molecular identification of Pseudomonas spp. was performed using the 16S rRNA gene sequence. Twelve commercially available antibiotics were used for antibiotic sensitivity tests using Kirby-Bauer disk diffusion methods. We isolated the most predominant isolates, Pseudomonas aeruginosa (41.67%), followed by Bacillus spp. (33.33%) and Staphylococcus spp. (25%) respectively. Among 12 antibiotics, ciprofloxacin is 100% sensitive against P. aeruginosa, while the remaining 11 antibiotics are 100% resistant. Bacillus spp. showed 100% resistance to all antibiotics while 50% sensitive to vancomycin and 100% to chloramphenicol, respectively. Staphylococcus spp. was 100% resistant to all antibiotics. Our research suggested that P. aeruginosa is the reservoir of antibiotic resistance genes and spreads disease to humans from the environment. The findings of this study, i.e., the isolation, identification, and characterization of antibiotic-resistant bacteria from pharmaceutical effluent have highlighted, comprehended, and mitigated the dissemination of antibiotic resistance and opportunistic bacteria.

Drivers of Antibiotic Resistance Gene Abundance in an Urban River

In this study, we sought to profile the abundances and drivers of antibiotic resistance genes in an urban river impacted by combined sewage overflow (CSO) events. Water samples were collected weekly during the summer for two years; then, quantitative PCR was applied to determine the abundance of resistance genes associated with tetracycline, quinolones, and β-lactam antibiotics. In addition to sampling a CSO-impacted site near the city center, we also sampled a less urban site ~12 km upstream with no proximal sewage inputs. The tetracycline genes tetO and tetW were rarely found upstream, but were common at the CSO-impacted site, suggesting that the primary source was untreated sewage. In contrast, ampC was detected in all samples indicating a more consistent and diffuse source. The two other genes, qnrA and blaTEM, were present in only 40-50% of samples and showed more nuanced spatiotemporal patterns consistent with upstream agricultural inputs. The results of this study highlight the complex sources of ARGs in urban riverine ecosystems, and that interdisciplinary collaborations across diverse groups of stakeholders are necessary to combat the emerging threat of antibiotic resistance through anthropogenic pollution.

Molecular Profile and the Effectiveness of Antimicrobials Drugs Against Staphylococcus aureus and Pseudomonas aeruginosa in the Diagnostic Approaches of Otitis Infection

Background

Otitis externa and otitis media are two types of ear infections that affect people of all ages, although they are more common in newborns and young children. Antibiotic usage, healthcare, and advanced age all play a role in the development of this illness.

Methods

Fifty-eight patients with various kinds of infections of the ears were voluntary patients attending the outpatient clinics of the Prince Mutaib Bin Abdulaziz Hospital in Sakaka, Al Jouf, Saudi Arabia, examined to evaluate the role of bacteria and the likely significance of plasmids in their antibiotic resistance as ear infectious agents.

Results

Staphylococcus aureus and Pseudomonas aeruginosa are the most prevalent bacteria found in ear infections. The greatest number of major bacterial isolates were S. aureus (54%), followed by P. aeruginosa (13%), whereas a smaller number of isolates (3%) were from Streptococcus pyogenes, Bacillus subtilis, and Proteus vulgaris, respectively. Mixed growth was noted in 3.4% of instances. The isolation rate for Gram-positive organisms was 72%, while the rate for Gram-negative species was 28%. All the isolates had DNA greater than 14 kilobases. Hind III analysis of the plasmid DNA extracted from the resistant strains of ear infection demonstrated that antibiotic-resistance plasmids were extensively dispersed. Exotoxin A PCR amplification indicated 396 pb PCR-positive DNA for all identified samples, with the exception of three strains for which no band was observed. Patients in the epidemiological study ranged in number, but all were linked together for the purposes of the study because of their shared epidemiological characteristics.

Conclusion

Vancomycin, linezolid, tigecycline, rifampin, and daptomycin are all antibiotics that have been shown to be effective against S. aureus and P. aeruginosa. Microbiological pattern evaluation and antibiotic sensitivity patterns of the microorganisms providing empirical antibiotics are becoming increasingly crucial to minimize issues and the development of antibiotic-resistant strains.

Detecting antibiotic resistance genes in anthropogenically impacted streams and rivers

Streams and rivers are widely impacted by human activities ranging from hydrological modifications to point and nonpoint pollution. Among the pollutants that enter lotic ecosystems are pharmaceuticals and personal care products, including antibiotics, that may play a role in the occurrence of antibiotic resistance genes (ARGs). Oftentimes, ARGs are detected based on culturing of bacteria or by using quantitative polymerase chain reaction; the limitations of these methods create barriers to our understanding. Use of more exhaustive methods, such as metagenomics, may overcome some of these barriers. The public health and ecological impacts of ARGs may be profound but are largely understudied. Antibiotic resistance is a growing concern for public health.

Antibiotic Resistance Profiles of Bacteria Isolated from Hotspot Environments in Bahir Dar City, Northwestern Ethiopia

Background

Wastes generated from hotspot environments contain a wide range of antibiotics and pathogens that play a significant role in the dissemination of antibiotic-resistant bacteria in the environment. This study was carried out to isolate bacteria from hotspot environments and determine their resistance profiles to commonly used antibiotics in Bahir Dar city, Ethiopia.

Methods

A cross-sectional study was conducted from October 2020 to June 2021 in Bahir Dar City. A total of 126 waste and wastewater samples were aseptically collected, transported, and processed for bacteriological isolation and susceptibility testing following standard procedures.

Results

A total of 411 bacterial isolates were recovered and the highest value of 122 (29.7%) bacterial isolates were obtained from medical wastewater samples, and the most frequently isolated bacteria were assigned to the species Escherichia coli with 82 strains (19.5%). The results revealed that the highest resistance profile of 69 (95.8%) was obtained in Staphylococcus aureus against ampicillin and 46 (86.8%) Citrobacter spp. against tetracycline. Two hundred and sixteen (52.6%) of bacteria showed multi-drug resistance and the highest multi-drug resistance was observed in Pseudomonas spp. 47 (65.3%), followed by Escherichia coli 51 (62.2%). The highest resistance profile of 12 (85.7%) and 60 (74.1%) for tetracycline were obtained from beef waste and wastewater and medical wastewater samples. The highest multi-drug resistance was recorded in isolates isolated from beef waste and wastewater samples 11 (64.7%), followed by medical wastewater samples 84 (64.1%). Even though a higher (>0.2) multi-antibiotic resistance index was found in all hotspot environments, the highest multi-antibiotic resistance index (0.477) was recorded in bacteria isolated from medical wastewater.

Conclusion

It was concluded that wastes generated from hotspot environments and released in the environment contain large numbers of antibiotic-resistant, multidrug, extensively, and pan-drug-resistant bacteria. Proper waste management strategies should be established.

Persistence of wastewater-associated antibiotic resistant bacteria in river microcosms

The spread of antibiotic-resistant bacteria (ARB) associated with wastewater is a significant environmental concern, but little is known about the persistence and proliferation of these organisms in receiving water bodies after discharge. To address this knowledge gap, we performed a series of microcosm experiments in which river water was amended with either untreated or treated wastewater, and the abundance of viable ciprofloxacin-, Bactrim-, and erythromycin-resistant bacteria was monitored for 72 h. Both types of wastewater amendments significantly increased the initial abundance of ARB compared to microcosms containing only river water (all p < 0.03). The increase was greatest with untreated wastewater, but that effect decreased steadily over time. In contrast, microcosms amended with treated wastewater saw a smaller initial increase and more complex temporal dynamics. Following a brief lag, ARB abundance bloomed for all three of the antibiotics that we considered. This suggests that ARB that survive wastewater treatment are particularly hardy and may proliferate in riverine conditions after a short recovery period. To determine how interactions with the native river microbial community impacted the persistence of wastewater-associated ARB, an additional set of microcosms was prepared using filter-sterilized river water. Peak abundance in these microcosms was significantly higher by 1-2 orders of magnitude compared to microcosms containing an intact river microbial community (all p < 0.05), which suggests that biotic interactions play a significant role in regulating the persistence and proliferation of ARB. The data presented in this paper are among the first available that specifically consider persistence of viable ARB and represent an important step toward understanding AR-related human health risks downstream from wastewater discharge points and following sewer overflow events. Additional studies that consider longer time scales and the interplay of biotic and abiotic variables are essential for modeling public health risks associated with wastewater inputs of ARB to rivers and other aquatic environments.

Quantifying and predicting antimicrobials and antimicrobial resistance genes in waterbodies through a holistic approach: a study in Minnesota, United States

The environment plays a key role in the spread and persistence of antimicrobial resistance (AMR). Antimicrobials and antimicrobial resistance genes (ARG) are released into the environment from sources such as wastewater treatment plants, and animal farms. This study describes an approach guided by spatial mapping to quantify and predict antimicrobials and ARG in Minnesota’s waterbodies in water and sediment at two spatial scales: macro, throughout the state, and micro, in specific waterbodies. At the macroscale, the highest concentrations across all antimicrobial classes were found near populated areas. Kernel interpolation provided an approximation of antimicrobial concentrations and ARG abundance at unsampled locations. However, there was high uncertainty in these predictions, due in part to low study power and large distances between sites. At the microscale, wastewater treatment plants had an effect on ARG abundance (sul1 and sul2 in water; bla_SHV, intl1, mexB, and sul2 in sediment), but not on antimicrobial concentrations. Results from sediment reflected a long-term history, while water reflected a more transient record of antimicrobials and ARG. This study highlights the value of using spatial analyses, different spatial scales, and sampling matrices, to design an environmental monitoring approach to advance our understanding of AMR persistence and dissemination.