Reservoir Of Antibiotic Resistant Bacteria Research Articles

Characterization of antimicrobial resistance profiles in Escherichia coli isolated from captive mammals in Ecuador.

This study focuses on the AMR profiles in E. coli isolated from captive mammals at EcoZoo San Martín, Baños de Agua Santa, Ecuador, highlighting the role of wildlife as reservoirs of resistant bacteria. The aim of this research is to investigate the antimicrobial resistance profiles of E. coli strains isolated from various species of captive mammals, emphasizing the potential zoonotic risks and the necessity for integrated AMR management strategies. A total of 189 fecal samples were collected from 70 mammals across 27 species. These samples were screened for E. coli, resulting in 90 identified strains. The resistance profiles of these strains to 16 antibiotics, including 10 β-lactams and 6 non-β-lactams, were determined using the disk diffusion method. Additionally, the presence of Extended-Spectrum Beta-Lactamase (ESBL) genes and other resistance genes was analyzed using PCR. Significant resistance was observed, with 52.22% of isolates resistant to ampicillin, 42.22% to ceftriaxone and cefuroxime, and 27.78% identified as ESBL-producing E. coli. Multiresistance (resistance to more than three antibiotic groups) was found in 35.56% of isolates. Carnivorous and omnivorous animals, particularly those with prior antibiotic treatments, were more likely to harbor resistant strains. These findings underscore the role of captive mammals as indicators of environmental AMR. The high prevalence of resistant E. coli in these animals suggests that zoos could be significant reservoirs for the spread of antibiotic-resistant bacteria. The results align with other studies showing that diet and antibiotic treatment history influence resistance profiles. The study highlights the need for an integrated approach involving veterinary care, habitat management, and public awareness to prevent captive wildlife from becoming reservoirs of antibiotic-resistant bacteria. Improved waste management practices and responsible antibiotic use are crucial to mitigate the risks of AMR in zoo environments and reduce zoonotic threats.

Genomic analysis of multidrug-resistant Escherichia coli from Urban Environmental water sources in Accra, Ghana, Provides Insights into public health implications.

Wastewater discharge into the environment in resource-poor countries poses a threat to public health. Studies in this area within these countries are limited, and the use of high-throughput whole-genome sequencing technologies is lacking. Therefore, understanding of environmental impacts is inadequate. The present study investigated the antibiotic resistance profiles and diversity of beta-lactamases in Escherichia coli strains isolated from environmental water sources in Accra, Ghana. Microbiological analyses were conducted on wastewater samples from three hospitals, a sewage and wastewater treatment plant, and water samples from two urban surface water bodies. Confirmed isolates (N = 57) were selected for phenotypic antibiotic resistance profiles. Multi-drug-resistant isolates (n = 25) were genome sequenced using Illumina MiSeq sequencing technology and screened for sequence types, antibiotic resistance, virulence and beta-lactamase genes, and mobile genetic elements. Isolates were frequently resistant to ampicillin (63%), meropenem (47%), azithromycin (46%), and sulfamethoxazole-trimethoprim (42%). Twenty different sequence types (STs) were identified, including clinically relevant ones such as ST167 and ST21. Five isolates were assigned to novel STs: ST14531 (n = 2), ST14536, ST14537, and ST14538. The isolates belonged to phylogroups A (52%), B1 (44%), and B2 (4%) and carried β-lactamase (TEM-1B, TEM-1C, CTX-M-15, and blaDHA-1) and carbapenemase (OXA-1, OXA-181) resistance genes. Dominant plasmid replicons included Col440I (10.2%) and IncFIB (AP001918) (6.8%). Polluted urban environments in Accra are reservoirs for antibiotic-resistant bacteria, posing a substantial public health risk. The findings underscore the need for targeted public health interventions to mitigate the spread of antibiotic-resistant bacteria and protect public health.

Extended-spectrum β-lactamase-producing bacteria and their resistance determinants in different wastewaters and rivers in Nepal

Wastewaters serve as significant reservoirs of antibiotic resistant bacteria. Despite the evidence of antimicrobial resistance in wastewaters and river water in Kathmandu, direct linkage between them is not discussed yet. This study investigated the prevalence of extended-spectrum β-lactamase (ESBL)-producing bacteria and associated resistance genes in wastewaters and river water. Out of 246 bacteria from wastewaters, 57.72% were ESBL producers and 77.64% of them were multidrug resistant (MDR). ESBL producing E. coli was dominant in municipal and hospital wastewaters (HWW) as well as in river water while K. pneumoniae was common in pharmaceutical wastewater. The blaSHV and blaTEM genes were prevalent and commonly co-occurred with aac(6')-Ib-cr in K. pneumoniae isolated pharmaceutical wastewater. blaCTX-M carrying E. coli from hospital co-harbored aac(6')-Ib-cr while that from municipal influent and river water co-harbored qnrS. Whole genome sequencing data revealed the presence of diverse ARGs in bacterial isolates against multiple antibiotics. In average, an E. coli and a K. pneumoniae isolate contained 55.75 ± 0.96 and 40.2 ± 5.36 ARGs, respectively. Multi-locus sequence typing showed the presence of globally high-risk clones with wider host range such as E. coli ST10, and K. pneumoniae ST15 and ST307 in HWW and river indicating frequent dissemination of antimicrobial resistance in wastewater of Kathmandu. Whole genome sequence data aligned with phenotypic antibiograms and resistance genes detected by PCR in selected isolates. The presence of significant plasmid replicons (IncF, IncY) and mobile genetic elements (IS903, IS26) indicate high frequency of spreading antibiotic resistance. These findings indicate burden and dissemination of antimicrobial resistance in the environment and highlight the need for effective strategies to mitigate the antibiotic resistance.

Removal of antibiotic resistant bacteria by the coupled system of ferrous ion activated peroxymonosulfate (PMS) and sodium percarbonate (SPC): Performance and mechanisms

Antibiotic resistance has turned into a focus of universal public health concern. Wastewater treatment plants are considered as reservoirs of antibiotic resistant bacteria (ARB) and antibiotic resistant genes (ARGs), which can be transmitted to the environment. In this research, an effective method for inactivating Escherichia coli DH5α (E. coli DH5α) carrying resistance genes was developed utilizing dual oxidant system of peroxymonosulfate (PMS) and sodium percarbonate (SPC) in the presence of ferrous ions (Fe(II)). The results indicated that E. coli DH5α could be inactivated 6.36 log under the conditions of 0.50 mM PMS, 0.50 mM SPC and 0.50 mM Fe(II) after 30 min. Besides, the removal of different types of ARB and pollutants could also be achieved by Fe(II)/PMS/SPC system. The quenching experiments and EPR analysis demonstrated that reactive species (•OH, SO4•−, O2•−, 1O2 and CO3•−) involved in the inactivation of E. coli DH5α. Bacterial damage mechanisms were systematically studied in terms of cell structure and morphology, enzyme activity, malondialdehyde and intracellular reactive oxygen species levels. The inactivation of E. coli DH5α in complex water matrix (including coexisting of anions and natural organic matter) and real wastewater was inhibited. The abundance of intracellular ARGs decreased by 1.15 log, whereas extracellular ARGs increased by 0.32 log. This research supplied a prospective approach for inhibiting the dissemination of antibiotic resistance.

Antibiotic Resistance in Seawater Samples from East Coast of Spain

Seawater has been proposed as a reservoir for antibiotic-resistant bacteria and antibiotic resistance genes, thus representing a risk to public health. In this study, we evaluated the presence of antibiotic resistance determinants (bacteria and genes) in 77 seawater samples collected at different points along the coast of the Gulf of Valencia (Spain). Specifically, indicators of fecal contamination bacteria, Escherichia coli and Enterococcus sp., were isolated, and their antibiotic resistance profiles were analyzed through the use of the Sensititre® system, followed by the detection of the main antibiotic resistance genes (blaTEM, qnrS, tetW, sulI, and ermB). The highest frequencies of resistance in the E. coli isolates were detected for ampicillin (35.1%) and ciprofloxacin (17.5%), followed by sulfamethoxazole and trimethoprim (15.7%), while 23% of enterococci isolates showed resistance to a single antibiotic, 20% against tetracycline and 3% against daptomycin. Through PCR analysis, 93% of the E. coli strains showed the blaTEM and sulI resistance genes. Among the enterococci, the presence of the blaTEM gene was detected in 40% of the isolates, while the rest of the genes were present at very low rates. Among the water samples, 57% were positive for at least one of the tested genes, italic format with blaTEM being the most commonly found gene (47%), followed by the qnrS (33%) and sulI (23%) genes. These results show that seawater, in addition to being subjected to a high rate of fecal contamination, can contribute to the spread of antibiotic resistance.

Exploring the effects of antimicrobial treatment on the gut and oral microbiomes and resistomes from elderly long-term care facility residents via shotgun DNA sequencing.

Monitoring antibiotic-resistant bacteria (ARB) and understanding the effects of antimicrobial drugs on the human microbiome and resistome are crucial for public health. However, no study has investigated the association between antimicrobial treatment and the microbiome-resistome relationship in long-term care facilities, where residents act as reservoirs of ARB but are not included in the national surveillance for ARB. We conducted shotgun metagenome sequencing of oral and stool samples from long-term care facility residents and explored the effects of antimicrobial treatment on the human microbiome and resistome using two types of comparisons: cross-sectional comparisons based on antimicrobial treatment history in the past 6 months and within-subject comparisons between stool samples before, during and 2-4 weeks after treatment using a single antimicrobial drug. Cross-sectional analysis revealed two characteristics in the group with a history of antimicrobial treatment: the archaeon Methanobrevibacter was the only taxon that significantly increased in abundance, and the total abundance of antimicrobial resistance genes (ARGs) was also significantly higher. Within-subject comparisons showed that taxonomic diversity did not decrease during treatment, suggesting that the effect of the prescription of a single antimicrobial drug in usual clinical treatment on the gut microbiota is likely to be smaller than previously thought, even among very elderly people. Additional analysis of the detection limit of ARGs revealed that they could not be detected when contig coverage was <2.0. This study is the first to report the effects of usual antimicrobial treatments on the microbiome and resistome of long-term care facility residents.

Enhanced phytoremediation of metal contaminated soils aimed at decreasing the risk of antibiotic resistance dissemination

The enhanced phytoremediation of metal contaminated soils holds great promise for the recovery of soil health and functionality, while providing a range of co-benefits, from an environmental and human health perspective, derived from the revegetation of the degraded sites and the concomitant delivery of ecosystem services. Due to diverse evolutionary co-selection mechanisms between metal resistance and antibiotic resistance in bacteria, metal contaminated soils are considered potential reservoirs of antibiotic resistant bacteria (ARB) which can contribute to the existing antibiotic resistance crisis. During the enhanced phytoremediation of metal contaminated soils, the application of organic wastes (e.g., manure, slurry, sewage sludge) as soil amendments can aggravate the risk of antibiotic resistance spread, because they often contain ARB which harbor antibiotic resistance genes (ARGs) that can then be propagated among soil bacterial populations through horizontal gene transfer (HGT). Due to the magnitude and criticality of the antibiotic resistance crisis, as well as the higher risk of spread and dispersal of ARB and ARGs (they make copies of themselves) compared to metals, it is proposed here to aim enhanced phytoremediation strategies towards decreasing the soil resistome (and, hence, the risk of its potential link with the human resistome), while reducing total and/or bioavailable metal concentrations and restoring soil health and the delivery of ecosystem services. To this purpose, a decalogue of practices is tentatively suggested. Finally, a proper management of plant and soil microbial compositions is a most crucial aspect, together with the selection of the right organic wastes and phytoremediation practices.

European Wild Carnivores and Antibiotic Resistant Bacteria: A Review.

Antibiotic resistance is a global concern that affects not only human health but also the health of wildlife and the environment. Wildlife can serve as reservoirs for antibiotic-resistant bacteria, and antibiotics in veterinary medicine and agriculture can contribute to the development of resistance in these populations. Several European carnivore species, such as wolves, foxes, otters, and bears, can be exposed to antibiotics by consuming contaminated food, water, or other resources in their habitats. These animals can also be indirectly exposed to antibiotics through interactions with domestic animals and human activities in their environment. Antibiotic resistance in wildlife can harm ecosystem health and also impact human health indirectly through various pathways, including zoonotic disease transmission. Moreover, the spread of resistant bacteria in wildlife can complicate conservation efforts, as it can threaten already endangered species. This review aims to describe the presence of antibiotic-resistant bacteria in wild carnivores in Europe.

Antimicrobial susceptibility profile of oral and rectal microbiota of non-human primate species in Ghana: A threat to human health.

The potential for the transfer of zoonotic diseases, including bacteria between human and non-human primates (NHPs), is expected to rise. It is posited that NHPs that live in close contact with humans serve as sentinels and reservoirs for antibiotic-resistant bacteria. The objective was to characterize the oral and rectal bacteria in Ghanaian NHPs and profile the antimicrobial susceptibility of the isolated bacteria. Oral and rectal swabs were obtained from 40 immobilized wild and captive NHPs from 7 locations in Ghana. Standard bacteriological procedures were used in the isolation, preliminary identification, automated characterization and antimicrobial susceptibility test (AST) of bacteria using the Vitek 2 Compact system. Gram-negative bacteria dominated isolates from the rectal swabs (n=76, 85.4%), whereas Gram-positive bacteria were more common in the oral swabs (n=41, 82%). Staphylococcus haemolyticus (n=7, 14%) was the most occurring bacterial species isolated from the oral swabs, whereas Escherichia coli (n=32, 36%) dominated bacteria isolates from rectal swabs. Enterobacter spp. had the highest (39%) average phenotypic resistance to antimicrobials that were used for AST, whereas a trend of high resistance was recorded against norfloxacin, Ampicillin and Tetracycline in Gram-negative bacteria. Similarly, among Gram-positive bacteria, Staphylococcus spp. had the highest (25%) average phenotypic resistance to antimicrobials used for AST, and a trend of high resistance was recorded against penicillin G and oxacillin. This study has established that apparently healthy NHPs that live in anthropized environments in Ghana harbour zoonotic and antimicrobial resistant bacteria.

A mesophilic phosphotriesterase-like lactonase shows high stability and proficiency as quorum quenching enzyme

The problem of biofilm formation is a serious concern under various pathological conditions such as extensive burns, wounds in diabetic patients, bedsores, cystic fibrosis, nosocomial infections from implantable medical devices such as catheters, valves, etc.Environmental diffusion of biofilm (in pools, wet floors, industrial food plants) that could represent a reservoir of antibiotic resistant bacteria constitues an additional issue.In this work is described a lactonase from Rhodococcus erythropolis, a phosphotriesterase-like lactonase (PLL) enzyme, which has already been studied in the past and can be used for containment of biofilm formation. The protein is 28% and 40% identical with respect to the Pseudomonas diminuta PTE and the thermostable Saccharolobus solfataricus SsoPox respectively. The protein was obtained starting from a synthetic His-tagged gene, expressed in E. coli, purified and further characterized. New properties, not previously known or deducible from its sequence, have been highlighted. These properties are: the enzyme is thermophilic and thermostable even though it originates from a mesophilic bacterium; the enzyme has a long (months) shelf life at 4 °C; the enzyme is not only stable to low concentrations of the oxidant H2O2 but even activated by it at high concentrations; the enzyme proved to be a proficient quorum quenching enzyme, able to hydrolase acyl-homoserine lactones 3oxoC12-HSL and C4-HSL, and can inhibit up to 60% the formation of Pseudomonas aeruginosa (PAO1) biofilm.These different properties make the lactonase useful to fight resistant bacteria that induce inflammatory and infectious processes mediated by the quorum sensing mechanism.

Spatial Analysis of the Occurrence of Multi-Drug Resistance (MDR) Escherichia coli in Pet Dogs in Kupang City

Spatial Analysis of the Occurrence of Multi-Drug Resistance (MDR) Escherichia coli in Pet Dogs in Kupang City

The Fate and Occurrence of Antibiotic-Resistant Bacteria and Antibiotic Resistance Genes during Advanced Wastewater Treatment and Disinfection: A Review

Antimicrobial resistance (AMR) is a serious problem for modern society, not only associated with clinical environments, but also the natural environment. Conventional wastewater treatment plants (WWTPs) are important nodes for the dissemination of antibiotic resistance to the aquatic environment since they are reservoirs of antibiotic-resistant bacteria (ARB), antibiotic resistance genes (ARGs), and antibiotic residues. WWTPs are not designed to remove these antibiotic resistance determinants from wastewater, and as a result, they are present in treated effluent, leading to environmental and public health concerns regarding wastewater disposal and reuse. Additional treatments combined with conventional WWTPs can be barriers to the spread of AMR to the environment. In order to understand the effect of wastewater treatment methods on the removal of ARB and ARGs, an extensive bibliographic study was conducted. This review summarizes the efficiency of conventional disinfection methods, tertiary wastewater treatment, and advanced oxidation processes (AOPs) to remove ARB and ARGs from wastewater. In the context of the revised Urban Wastewater Treatment Directive 91/271/EEC, further studies are needed on the removal potential of AOPs on a full-scale, as they offer great potential for the removal of ARB and ARGs with a low formation of toxic by-products compared to conventional disinfection methods.

Abundance and phenotypic-genotypic analysis of antibiotic-resistant Escherichia coli isolated from wastewater of the Zainoel Abidin Hospital, Banda Aceh, Indonesia

Abstract. Anelia N, Suhartono S, Hayati Z. 2023. Abundance and phenotypic-genotypic analysis of antibiotic-resistant Escherichia coli isolated from wastewater of the Zainoel Abidin Hospital, Banda Aceh, Indonesia. Biodiversitas 24: 2294-2301. Excessive and inappropriate use of antibiotics can initiate the emergence of antibiotic resistance in bacteria. Wastewater Treatment Plant (WWTP) is believed to be a reservoir for antibiotic-resistant bacteria, including Escherichia coli. This study aimed to perform the enumeration, isolation, characterization, and evaluation of resistance properties and antibiotic resistance-coding genes encoded by a plasmid of E. coli isolates from WWTP of the dr. Zainoel Abidin General Hospital (RSUDZA). The study was conducted through several stages, including the isolation and quantification of E. coli, antibiotic resistance testing, confirmation testing of ESBL-E. coli isolates, isolation of plasmid DNA, and amplification of TEM, SHV, and CTX-M genes. The results showed that the wastewater in the sum pit tank, aeration tank, and final tank of the WWTP contained E. coli at 7.5x104 CFU/mL, 3x102 CFU/mL, and 1x102 CFU/mL, respectively. A total of 22 isolates were obtained, with ten isolates from the sum pit tank, seven from the aeration tank, and five from the final tank. Escherichia coli isolates had resistance to eight types of antibiotics in the aeration tank and seven types in the final tank, compared to the sum pit tank of the WWTP. Therefore, 59% of the isolates were classified as Multi-drug Resistant (MDR) and 32% as Extended Spectrum ?-Lactamase E. coli (ESBL-EC). TEM, SHV, and CTX-M genes were detected in all locations at 63.6%, 22.7%, and 95.5%, respectively. In addition, CTX-M was the most common gene found in wastewater isolates at RSUDZA WWTP. The hospital wastewater treatment process must be improved to reduce the presence of antibiotic-resistant bacteria and the spread of antibiotic resistance genes.

Anthropogenic and natural disturbances along a river and its estuary alter the diversity of pathogens and antibiotic resistance mechanisms

Antibiotic resistance (AMR) in pathogens threatens human health worldwide, and antibiotic-resistant bacteria (ARB) are widespread in the environment. In particular, anthropogenically-disturbed rivers became reservoirs of ARBs and hotspots of antibiotic resistance gene (ARG) transmission. However, the diversity and sources of ARB, and the mechanisms of ARG transmission are not fully known. Here, we used deep metagenomic sequencing to study the dynamics of pathogens and their antibiotic resistance mechanisms along the Alexander River (Israel), affected by sewage and animal farm runoffs. Putative pathogens such as Aeromicrobium marinum and Mycobacterium massilipolynesiensis were enriched in western stations, following the inputs of polluted Nablus River. Aeromonas veronii was dominant in eastern stations in Spring. Several AMR mechanisms showed distinct patterns in Summer-Spring (dry season) and Winter (rainy season). We found low abundance beta-lactamases conferring carbapenem resistance: e.g., OXA-912 was linked to A. veronii in Spring; OXA-119 and OXA-205 to Xanthomonadaceae in Winter. We classified 33 % of ARG-containing contigs as putative plasmid sequences, indicating the high potential for resistome transmission. A limited number of ARGs were linked to putative phages. Our results suggest that this model river is a hotspot for AMR activity and transmission, and highlight the merit of deep sequencing for AMR discovery.

Systematic Survey of Vibrio spp. and Salmonella spp. in Bivalve Shellfish in Apulia Region (Italy): Prevalence and Antimicrobial Resistance

The emergence of antimicrobial resistance (AMR) is increasingly common across the globe and aquatic ecosystems could be considered a reservoir of antibiotic-resistant bacteria. This study aimed to determine prevalence and antibiotic susceptibility of the potential pathogenic bacteria Salmonella spp. and Vibrio spp. in bivalve molluscs intended for human consumption, collected over a period of 19 months along the northern coast of Apulia region. The AMR profile was also determined in non-pathogenic Vibrio species, common natural inhabitants of seawater and a useful indicator for the surveillance of AMR in the environment. The current study presents data on the AMR of 5 Salmonella and 126 Vibrio isolates by broth microdilution MIC. Multidrug resistance (MDR) was observed in one S. Typhimurium strain towards sulfamethoxazole, trimethoprim, tetracycline, gentamicin, and ampicillin and in 41.3% of the Vibrio strains, mostly towards sulphonamides, penicillin, and cephems. All Vibrio isolates were sensitive to azithromycin, chloramphenicol, tetracycline, amoxicillin/clavulanic acid, gentamicin, streptomycin, amikacin, and levofloxacin. The AMR phenomenon in the investigated area is not highly worrying but not entirely negligible; therefore, in-depth continuous monitoring is suggested. Results concerning the antibiotic agents without available specific clinical breakpoints could be useful to upgrade the MIC distribution for Vibrio spp. but, also, the establishment of interpretative criteria for environmental species is necessary to obtain a more complete view of this issue.

Occurrence of extended spectrum β-lactamases, AmpC β-lactamase and sulfonamide resistance genes in ESBL-producing Escherichia coli recovered from faecal matter of lizards

ABSTRACT The occurrence of β-lactamases and sulfonamide resistance genes in ESBL-producing E. coli from faecal matter of lizards was investigated. Isolation of ESBL-producing E. coli from lizard faecal matter was done on CHROMagar ESBL, and identification was done using molecular method. Disc diffusion method was used for the antibiotic susceptibility testing and detection of β-lactamases and sulfonamide resistance genes was done using PCR. Six ESBL-producing E. coli isolates were obtained. All the isolates obtained were multidrug resistant, showing a high level of resistance to the tested antibiotics. Five isolates carried at least one of the variants of bla CTX-M and sul2, one isolate carried sul1, while bla CMY was detected in three isolates, with two isolates carrying bla SHV and bla TEM concurrently. One isolate did not carry any of the genes. This study showed that faecal matter from lizards could be a reservoir of antibiotic resistant bacteria and resistance genes.

Conjugation-mediated transfer of antibiotic resistance genes influenced by primary soil components and underlying mechanisms

Soil is the main natural reservoir of antibiotic resistant bacteria and antibiotic resistance genes (ARGs). Their dissemination and proliferation were largely motivated by conjugative transfer, while the influence of soil components on bacterial conjugative transfer and the underlying mechanisms remain poorly understood. In the present study, two Escherichia coli strains were exposed to soil minerals (quartz, kaolinite and montmorillonite) and organic matters (humic acid, biochar and soot) respectively to investigate their impact on ARGs conjugation. The results showed that quartz had no significant effect on conjugation; montmorillonite promoted the growth of the donor, but inhibited the recipient and conjugant; kaolinite and three organic matters significantly promoted the production of conjugant, while biochar promoted and then inhibited it with time prolong. Within the range of bacterial concentration involved in this study, the concentration of conjugant increased with the ratio of the concentration of donor and recipient (RD/R), indicating that the variation of conjugant production was mainly mediated by changing RD/R. Further observation of biochar treatment group showed that the bacterial responses such as cell membrane permeability, cell surface hydrophobicity and biofilm formation ability shifted with the exposure time, which might be a potential factor affecting conjugative transfer. Collectively, our findings suggest that the type and exposure time of soil components jointly affected conjugation, while the change of RD/R and related bacterial responses are the main underlying mechanisms.

A potential role of cockroaches in the transmission of pathogenic bacteria with antibiotic resistance: A scoping review.

The role of cockroaches in the cause of disease or human infections is not immediately obvious. The present study aimed to review the currently available research on the potential role of cockroaches in the transmission of pathogenic bacteria and bacteria with antibiotic resistance. A scoping review included the studies published for a period between January 2001 and December 2020. A search was performed through five databases, namely, PubMed, Sage, Springer, Sabinet, and Science Direct. A search strategy used was conducted according to the principles of Preferred Reporting Item for Systemic Reviews and Meta-Analyses (PRISMA). From 97 studies identified, 32 studies were included in the scoping review. The findings indicate that cockroaches may be a potential vector for a diverse range of pathogenic bacterial agents. Most bacterial agents isolated are antidrug-resistant and antibiotic-resistant which is considered the greatest threat to public health in the current period. Cockroach infestation should be considered as a serious concern, given the possible role of cockroaches as reservoirs of antibiotic-resistant bacteria. Further research is needed which can provide a comprehensive understanding of the role of cockroaches in transmitting human infections.

Prevalence of antimicrobial resistance in a Bulgarian drinking water supply system

Abstract Drinking water quality and safety are of great concern for public health. The aim of this study was to assess the prevalence of antimicrobial resistance (AMR) among the heterotrophic bacteria in drinking water provided by a Bulgarian drinking water supply system (DWSS). Culture-dependent methods and conventional PCR assays were used to study drinking water sampled from six locations on its way from the water source to the consumers' taps. The populations of bacteria resistant to nine antibiotics (ABs) from different classes were quantified and the occurrence of seven antibiotic resistance genes (ARG) was determined. The species composition of the bacterial community and the AMR phenotype of isolated bacteria were determined. The AMR level underwent changes within the DWSS network and the population's proportion of bacteria resistant towards the tested ABs differed depending on the sampling site. The increased level of resistance towards some ABs in drinking water emphasize the role of DWSS as a reservoir of antibiotic-resistant bacteria (ARB) and ARGs that could pose a potential human health risk. Being focused on a Bulgarian DWSS, our study will contribute to establishing health hazards associated with ARB and ARGs in drinking water.

Temporal dynamics of antibiotic resistant bacteria and antibiotic resistance genes in activated sludge upon exposure to starvation

The activated sludge represents a huge reservoir for antibiotic resistant bacteria (ARB) and antibiotic resistance genes (ARGs). Owing to the wastewater fluctuation, annual maintenance and storage requirement, the activated sludge in wastewater treatment plants (WWTPs) may suffer from substrate deficiency (i.e., starvation). Whereas the starvation has been confirmed to regulate the antibiotic resistance in numerous pure bacteria, its impacts on the antibiotic resistance in activated sludge remain unclear. Here, the dynamics of sulfonamide and tetracycline ARB and corresponding ARGs in three forms including intracellular ARGs (iARGs), adsorbed extracellular ARGs (aeARGs) and free extracellular ARGs (feARGs) in activated sludge upon exposure to starvation were investigated. The results showed that, among the different electron donors (i.e., carbon, nitrogen and phosphate), carbon starvation could effectively reduce the absolute abundance of ARB and aeARGs by up to 1.68 lgs and 2.62 lgs, respectively, and released a small amount of feARGs in wastewater with the maximum value of 1.1 × 105 copies/mL due to the high degree of sludge cell lysis and DNA adsorption/degradation. For the different acceptor conditions (that is, alternating anaerobic-aerobic, anaerobic, anoxic and aerobic), the anaerobic-aerobic starvation obviously mitigated the absolute abundance of ARB, aeARGs and iARGs by 0.71 lgs, 3.41 lgs and 1.35 lgs, respectively, via the substantial sludge cell lysis and DNA degradation. These findings demonstrated the response patterns and mechanisms of bacterial resistance in activated sludge to starvation stress, and thus provide clues to control the risk of antibiotic resistance in WWTPs by the starvation strategy.