Characterization of staphylococci in urban wastewater treatment plants in Spain, with detection of methicillin resistant Staphylococcus aureus ST398

Multidrug-Resistant Staphylococcus sp. and Enterococcus sp. in Municipal and Hospital Wastewater: A Longitudinal Study

The objective of the study was to detect multidrug-resistant Staphylococcus sp. and Enterococcus sp. isolates in municipal and hospital wastewater and to determine their elimination or persistence after wastewater treatment. Between August 2021 and September 2022, raw and treated wastewater samples were collected at two hospital and two community wastewater treatment plants (WWTPs). In each season of the year, two treated and two raw wastewater samples were collected in duplicate at each of the WWTPs studied. Screening and presumptive identification of staphylococci and enterococci was performed using chromoagars, and identification was performed with the Matrix Assisted Laser Desorption Ionization Time of Flight mass spectrometry (MALDI-TOF MS®). Antimicrobial susceptibility was performed using VITEK 2® automated system. There were 56 wastewater samples obtained during the study period. A total of 182 Staphylococcus sp. and 248 Enterococcus sp. were identified. The highest frequency of Staphylococcus sp. isolation was in spring and summer (n = 129, 70.8%), and for Enterococcus sp. it was in autumn and winter (n = 143, 57.7%). Sixteen isolates of Staphylococcus sp. and sixty-three of Enterococcus sp. persisted during WWTP treatments. Thirteen species of staphylococci and seven species of enterococci were identified. Thirty-one isolates of Staphylococcus sp. and ninety-four of Enterococcus sp. were multidrug-resistant. Resistance to vancomycin (1.1%), linezolid (2.7%), and daptomycin (8.2%/10.9%%), and a lower susceptibility to tigecycline (2.7%), was observed. This study evidences the presence of Staphylococcus sp. and Enterococcus sp. resistant to antibiotics of last choice of clinical treatment, in community and hospital wastewater and their ability to survive WWTP treatment systems.

A look at staphylococci from the one health perspective

Staphylococcus aureus and other staphylococcal species are resident and transient multihost colonizers as well as conditional pathogens. Especially S. aureus represents an excellent model bacterium for the "One Health" concept because of its dynamics at the human-animal interface and versatility with respect to host adaptation. The development of antimicrobial resistance plays another integral part. This overview will focus on studies at the human-animal interface with respect to livestock farming and to companion animals, as well as on staphylococci in wildlife. In this context transmissions of staphylococci and of antimicrobial resistance genes between animals and humans are of particular significance.

Antibiotic Resistance Genes, Virulence Factors, and Biofilm Formation in Coagulase-Negative Staphylococcus spp. Isolates from European Hakes (Merluccius merluccius, L.) Caught in the Northeast Atlantic Ocean

The indiscriminate use of antibiotics has contributed to the dissemination of multiresistant bacteria, which represents a public health concern. The aim of this work was to characterize 27 coagulase-negative staphylococci (CoNS) isolated from eight wild Northeast Atlantic hakes (Merluccius merluccius, L.) and taxonomically identified as Staphylococcus epidermidis (n = 16), Staphylococcus saprophyticus (n = 4), Staphylococcus hominis (n = 3), Staphylococcus pasteuri (n = 2), Staphylococcus edaphicus (n = 1), and Staphylococcus capitis (n = 1). Biofilm formation was evaluated with a microtiter assay, antibiotic susceptibility testing was performed using the disk diffusion method, and antibiotic resistance and virulence determinants were detected by PCR. Our results showed that all staphylococci produced biofilms and that 92.6% of the isolates were resistant to at least one antibiotic, mainly penicillin (88.8%), fusidic acid (40.7%), and erythromycin (37%). The penicillin resistance gene (blaZ) was detected in 66.6% (18) of the isolates, of which 10 also carried resistance genes to macrolides and lincosamides (mphC, msr(A/B), lnuA, or vgaA), 4 to fusidic acid (fusB), and 3 to trimethoprim-sulfamethoxazole (dfrA). At least one virulence gene (scn, hla, SCCmecIII, and/or SCCmecV) was detected in 48% of the isolates. This study suggests that wild European hake destined for human consumption could act as a vector of CoNS carrying antibiotic resistance genes and/or virulence factors.

Detection of mecA positive staphylococcal species in a wastewater treatment plant in South Africa

We investigated the prevalence of antibiotic resistant staphylococci and detection of resistant, virulence, and Spa genes in a South African wastewater treatment plant. Species identified were Staphylococcus aureus, S. lentus, S. arlettae, S. cohnii, S. haemolyticus, S. nepalensis, S. sciuri (now Mammaliicoccus sciuri), and S. xylosus. Isolates showed high resistance to methicillin (91%), ampicillin (89%), ciprofloxacin (86%), amoxycillin (80%), ceftazidime (74%), and cloxacillin (71%). Multiple antibiotic resistance (MAR) index for the isolates exceeded 0.2 (0.50-0.70). Among the isolates, 77% were mecA-positive. All S. aureus strains were positive for nuc and 7 Spa gene types. The present study highlights possibility of treated wastewaters being potential reservoir for antibiotic-resistant staphylococci. This is a cause for concern as wastewater effluents are decanted into environmental waters and these are, in many cases, used for various purposes including recreation (full contact), religious (full body submersion), and drinking water for some rural communities and water for livestock.

Wastewater surveillance beyond COVID-19: a ranking system for communicable disease testing in the tri-county Detroit area, Michigan, USA

Introduction

Throughout the coronavirus disease 2019 (COVID-19) pandemic, wastewater surveillance has been utilized to monitor the disease in the United States through routine national, statewide, and regional monitoring projects. A significant canon of evidence was produced showing that wastewater surveillance is a credible and effective tool for disease monitoring. Hence, the application of wastewater surveillance can extend beyond monitoring SARS-CoV-2 to encompass a diverse range of emerging diseases. This article proposed a ranking system for prioritizing reportable communicable diseases (CDs) in the Tri-County Detroit Area (TCDA), Michigan, for future wastewater surveillance applications at the Great Lakes Water Authority's Water Reclamation Plant (GLWA's WRP).

Methods

The comprehensive CD wastewater surveillance ranking system (CDWSRank) was developed based on 6 binary and 6 quantitative parameters. The final ranking scores of CDs were computed by summing the multiplication products of weighting factors for each parameter, and then were sorted based on decreasing priority. Disease incidence data from 2014 to 2021 were collected for the TCDA. Disease incidence trends in the TCDA were endowed with higher weights, prioritizing the TCDA over the state of Michigan.

Results

Disparities in incidences of CDs were identified between the TCDA and state of Michigan, indicating epidemiological differences. Among 96 ranked CDs, some top ranked CDs did not present relatively high incidences but were prioritized, suggesting that such CDs require significant attention by wastewater surveillance practitioners, despite their relatively low incidences in the geographic area of interest. Appropriate wastewater sample concentration methods are summarized for the application of wastewater surveillance as per viral, bacterial, parasitic, and fungal pathogens.

Discussion

The CDWSRank system is one of the first of its kind to provide an empirical approach to prioritize CDs for wastewater surveillance, specifically in geographies served by centralized wastewater collection in the area of interest. The CDWSRank system provides a methodological tool and critical information that can help public health officials and policymakers allocate resources. It can be used to prioritize disease surveillance efforts and ensure that public health interventions are targeted at the most potentially urgent threats. The CDWSRank system can be easily adopted to geographical locations beyond the TCDA.

Wastewater treatment plants, an "escape gate" for ESCAPE pathogens

Antibiotics are an essential tool of modern medicine, contributing to significantly decreasing mortality and morbidity rates from infectious diseases. However, persistent misuse of these drugs has accelerated the evolution of antibiotic resistance, negatively impacting clinical practice. The environment contributes to both the evolution and transmission of resistance. From all anthropically polluted aquatic environments, wastewater treatment plants (WWTPs) are probably the main reservoirs of resistant pathogens. They should be regarded as critical control points for preventing or reducing the release of antibiotics, antibiotic-resistant bacteria (ARB), and antibiotic-resistance genes (ARGs) into the natural environment. This review focuses on the fate of the pathogens Enterococcus faecium, Staphylococcus aureus, Clostridium difficile, Acinetobacter baumannii, Pseudomonas aeruginosa, and Enterobacteriaceae spp. (ESCAPE) in WWTPs. All ESCAPE pathogen species, including high-risk clones and resistance determinants to last-resort antibiotics such as carbapenems, colistin, and multi-drug resistance platforms, were detected in wastewater. The whole genome sequencing studies demonstrate the clonal relationships and dissemination of Gram-negative ESCAPE species into the wastewater via hospital effluents and the enrichment of virulence and resistance determinants of S. aureus and enterococci in WWTPs. Therefore, the efficiency of different wastewater treatment processes regarding the removal of clinically relevant ARB species and ARGs, as well as the influence of water quality factors on their performance, should be explored and monitored, along with the development of more effective treatments and appropriate indicators (ESCAPE bacteria and/or ARGs). This knowledge will allow the development of quality standards for point sources and effluents to consolidate the WWTP barrier role against the environmental and public health AR threats.

Genomic Characterization of Staphylococcus aureus in Wildlife

Staphylococcus aureus is an opportunistic multi-host pathogen that threatens both human and animal health. Animals can act as a reservoir of S. aureus for humans, but very little is known about wild animals’ epidemiological role. Therefore, in this study, we performed a genomic characterization of S. aureus isolates from wildlife, hunters, and their auxiliary hunting animals of Eastern Spain. Of 20 different species, 242 wild animals were examined, of which 28.1% were S. aureus carriers. The common genet, the Iberian ibex, and the European hedgehog were the species with the highest S. aureus carriage. We identified 30 different sequence types (STs), including lineages associated with wild animals such as ST49 and ST581, multispecies lineages such as ST130, ST398, and ST425, and lineages commonly isolated from humans, including ST1 and ST5. The hunters and the single positive ferret shared ST5, ST398, or ST425 with wild animals. In wildlife isolates, the highest resistance levels were found for penicillin (32.8%). For virulence factors, 26.2% of them carried superantigens, while 14.8% harbored the immune evasion cluster (IEC), which indicates probable human origin. Our findings suggest that wild animals are a reservoir of clinically relevant genes and lineages that could have the potential to be transmitted to humans. These data support the notion that wildlife surveillance is necessary to better understand the epidemiology of S. aureus as a pathogen that circulates among humans, animals, and the environment.

Novel Semiconductor Cu(C3H3N3S3)3/ZnTiO3/TiO2 for the Photoinactivation of E. coli and S. aureus under Solar Light

The use of semiconductors for bacterial photoinactivation is a promising approach that has attracted great interest in wastewater remediation. The photoinactivator Cu-TTC/ZTO/TO was synthesized by the solvothermal method from the coordination complex Cu(C₃H₃N₃S₃)₃ (Cu-TTC) and the hybrid semiconductor ZnTiO₃/TiO₂ (ZTO/TO). In this study, the effect of photocatalyst composition/concentration as well as radiation intensity on the photoinactivation of the gram-negative bacteria Escherichia coli and the gram-positive bacteria Staphylococcus aureus in aqueous solutions was investigated. The results revealed that 25 mg/mL of photoinactivator, in a Cu-TTC:ZTO/TO molar ratio of 1:2 (w/w%) presents a higher rate of bacterial photoinactivation under simulated solar light (λ = 300-800 nm) in comparison to the individual components. The evidence of this study suggests that the presence of the Cu(C₃H₃N₃S₃)₃ coordination complex in the ZnTiO₃/TiO₂ hybrid semiconductor would contribute to the generation of reactive oxygen species (ROS) that are essential to initiate the bacterial photoinactivation process. Finally, the results obtained allow us to predict that the Cu-TTC/ZTO/TO photocatalyst could be used for effective bacterial inactivation of E. coli and S. aureus in aqueous systems under simulated solar light.

Evaluation of the Occurrence of Staphylococcaceae with Reduced Susceptibility to Cefoxitin in Wild Ungulates in Brandenburg, Germany, Based on Land Use-Related Factors

Interactions between natural and human-used environments have a significant influence on the spread of antimicrobial resistance in wild ecosystems. Despite current knowledge, fundamental questions about the degree of impact of land use-related factors on the spread of antimicrobial-resistant staphylococci in European wild game animal populations have not yet been answered with certainty. In this study, we evaluated the occurrence of Staphylococcaceae showing reduced susceptibility to cefoxitin in nasal swabs of fallow deer (Dama dama), red deer (Cervus elaphus), roe deer (Capreolus capreolus), and wild boar (Sus scrofa) hunted in Brandenburg, Germany. Evaluations were focused on the use of open-source data regarding the extent as well as the degree of land use, especially for settlement or animal husbandry. Results showed that the detection rate of Staphylococcaceae showing a non-wild-type phenotype for cefoxitin differed between animal species of the studied hunting districts. Statistical analyses of results combined with data on land use features revealed that a high density of cattle or poultry in a county may be associated with an increased detection rate in roe deer or wild boar, respectively. Furthermore, positive correlations were determined between the prevalence of non-wild-type Staphylococcaceae in roe deer or fallow deer and the proportional extent of surface water bodies in the corresponding area. The presented approach establishes a general basis for a risk-oriented assessment of the effects of human activities on the epidemiology of transmissible microorganisms in the human-animal-environment interface, including antimicrobial-resistant bacteria. IMPORTANCE Intensive research regarding the impact of land use-related factors on the prevalence and distribution of antimicrobial-resistant Staphylococcaceae in game ungulate populations is necessary for adequately determining risks related to interactions between wild animals, domestic animals, and humans in common geographic locations. This systematic approach for the analysis of the observations in specific hunting districts of Brandenburg, Germany, adds an innovative value to the research strategy of antimicrobial resistance in wild game animals, which is in accordance with current recommendations worldwide. Thus, results and information obtained in this study build a relevant foundation for future risk assessment regarding the safety of game products. Furthermore, the data generated represent an important basis for improving existing guidelines in land use practices and hunting practices. The use of existing open source data collections provided by official governmental and nongovernmental entities increases not only the impact but also the applicability and comparability of information beyond the regional level.

Evidence of cross-contamination of waste workers and transmission of antimicrobial resistance genes by coagulase-negative Staphylococcus isolated from dental solid waste: an intriguing study

The aim of this study was to phenotypically and genotypically identify coagulase-negative Staphylococcus (CoNS) recovered from the nostrils of waste workers and from dental waste; 135 strains were recovered and S. epidermidis was the prevailing species. Genetic similarity (100%) was observed between the two S. epidermidis isolated from different employees on the same shift and 85% similarity between the S. epidermidis recovered from an employee's nostril and from waste. The mecA gene was found in 20 CoNS, and 20% were also found to possess the vanA gene. The blaZ gene was detected in 46.7%, and the icaA (34.8%), B and C genes (11.8% each). Our findings emphasized the biological risk to which waste workers are exposed and unprecedently confirms that it was possible to recover genetically identical bacterial species from waste and from workers' nostrils. It is important to highlight that this risk is raised by the detection of relevant antimicrobial resistance genes. The results also suggest that effective measures to correctly manage waste and promote the rational use of antimicrobials should be adopted.

High Frequency of the EMRSA-15 Clone (ST22-MRSA-IV) in Hospital Wastewater

Hospital wastewaters often carry multidrug-resistant bacteria and priority pathogens, such as methicillin-resistant Staphylococcus aureus (MRSA). Pathogens and antibiotic resistance genes present in wastewaters may reach the natural environment facilitating their spread. Thus, we aimed to isolate MRSA from wastewater of 3 hospitals located in the north of Portugal and to characterize the isolates regarding the antimicrobial resistance and genetic lineages. A total of 96 wastewater samples were collected over six months. The water was filtered, and the filtration membrane was immersed in BHI broth supplemented with 6.5% of NaCl and incubated. The inoculum was streaked in ORSAB agar plates for MRSA isolation. The isolates susceptibility testing was performed against 14 antimicrobial agents. The presence of resistance and virulence genes was accessed by PCR. Molecular typing was performed in all isolates. From the 96 samples, 28 (29.2%) were MRSA-positive. Most isolates had a multidrug-resistant profile and carried the mecA, blaZ, aac(6')-Ie-aph(2″)-Ia, aph(3')-IIIa, ermA, ermB, ermC, tetL, tetM, dfrA dfrG and catpC221 genes. Most of the isolates were ascribed to the immune evasion cluster (IEC) type B. The isolates belonged to ST22-IV, ST8-IV and ST105-II and spa-types t747, t1302, t19963, t6966, t020, t008 and tOur study shows that MRSA can be found over time in hospital wastewater. The wastewater treatment processes can reduce the MRSA load. The great majority of the isolates belonged to ST22 and spa-type t747 which suggests the fitness of these genetic lineages in hospital effluents.

The risk of transmitting antibiotic resistance through endophytic bacteria

Antibiotic resistance is a global human health threat distributed across humans, animals, plants, and the environment. Under the One-Health concept (humans, animals, and environment), the contamination of water bodies and soil by antibiotic-resistant bacteria cannot be dissociated from its potential transmission to humans. Edible plants can be colonized by a vast diversity of bacteria, representing an important link between the environment and humans in the One-Health triad. Based on multiple examples of bacterial groups that comprise endophytes reported in edible plants, and that have close phylogenetic proximity with human opportunistic pathogens, we argue that plants exposed to human-derived biological contamination may represent a path of transmission of antibiotic resistance to humans.

Antibiotic Resistance and Pathogenomics of Staphylococci Circulating in Novosibirsk, Russia

A total of 394 strains of staphylococci found in humans and pets in Novosibirsk, Siberian Russia, were characterized in terms of antibiotic resistance and corresponding genes. Two coagulase-positive and 17 coagulase-negative species were identified. The majority of isolates, with the exception of S. haemolyticus and hospital S. epidermidis isolates, were sensitive to most of the tested antibiotics, and isolates from pets displayed the lowest level of resistance. Nevertheless, methicillin-resistant (MRS) and/or multidrug-resistant (MDR) isolates were found in all prevailed species, including coagulase-negative. A set of genes corresponding to the detected resistance was identified: mecA (beta-lactam resistance), aac(6')-Ie-aph(2″)-Ia, aph(3')-IIIa, ant(4')-Ia (aminoglycoside-modifying enzymes), ermA/ermC, and msrA (macrolide resistance). Complete genome analysis for ten MDR S. epidermidis and five MDR S. haemolyticus isolates revealed additional antibiotic resistance genes mphC, qacA/qacB, norA, dfrC/dfrG, lnuA, BseSR, and fosB. NorA, dfrC, and fosB were present in all S. epidermidis genomes, whereas mphC and msrA were identified in all S. haemolyticus ones. All investigated MDR S. epidermidis and four of five S. haemolyticus strains were moderate or strong biofilm producers, whereas multiple genes responsible for this function and for virulence and pathogenicity were identified mostly in S. epidermidis, but were less frequently represented in S. haemolyticus.

Multi-species host range of staphylococcal phages isolated from wastewater

The host range of bacteriophages defines their impact on bacterial communities and genome diversity. Here, we characterize 94 novel staphylococcal phages from wastewater and establish their host range on a diversified panel of 117 staphylococci from 29 species. Using this high-resolution phage-bacteria interaction matrix, we unveil a multi-species host range as a dominant trait of the isolated staphylococcal phages. Phage genome sequencing shows this pattern to prevail irrespective of taxonomy. Network analysis between phage-infected bacteria reveals that hosts from multiple species, ecosystems, and drug-resistance phenotypes share numerous phages. Lastly, we show that phages throughout this network can package foreign genetic material enclosing an antibiotic resistance marker at various frequencies. Our findings indicate a weak host specialism of the tested phages, and therefore their potential to promote horizontal gene transfer in this environment.

Diversity and genetic lineages of environmental staphylococci: a surface water overview

Antimicrobial resistance in the environmental dimension is one of the greatest challenges and emerging threats. The presence of resistant bacteria and resistance genes in the environment, especially in aquatic systems, has been a matter of growing concern in the past decade. Monitoring the presence of antimicrobial resistance species, in this particular case, Staphylococcus spp., in natural water environments could lead to a better understanding of the epidemiology of staphylococci infections. Thus, the investigation of natural waters as a potential reservoir and vehicle for transmission of these bacteria is imperative. Only a few studies have investigated the prevalence, antimicrobial resistance and genetic lineages of staphylococci in natural waters. Those studies reported a high diversity of staphylococci species and lineages in surface waters. Methicillin-resistant S. aureus were relatively prevalent in surface waters and, as expected, often presented a multidrug-resistant profile. There was a high diversity of S. aureus lineages in surface waters. The presence of S. aureus CC8 and CC5 suggests a human origin. Among the coagulase-negative staphylococci, the most frequently found in natural waters was S. warneri and S. epidermidis. These studies are extremely important to estimate the contribution of the aquatic environment in the spread of pathogenic bacteria.

Antibiotic-resistant staphylococci from the wastewater treatment plant and grey-water samples in Obafemi Awolowo University, Ile-Ife, Nigeria

This study examined the occurrence and molecular basis for antibiotic-resistant staphylococci from the wastewater treatment plant and grey-water samples in Obafemi Awolowo University, Nigeria. Standard microbiological techniques and molecular methods were utilized. The species identified (MALDI score >1.7) comprised S. saprophyticus (19), S. cohnii (8), S. sciuri (7), S. aureus (4), S. epidermidis (3), S. warneri (2), S. equorum (1), S. haemolyticus (1), S. nepalensis (1), S. condimenti (1), and S. pasteuri (1). Resistance to trimethoprim, tetracycline and cefoxitin were observed in 78.3% (47/60), 36.7% (22/60) and 25% (15/60) of the isolates, respectively. The rate of multidrug resistance was 53.3% (32/60) and observed in eight species from different sampling sites. Seven (S. sciuri; n = 5; S. aureus; n = 1; S. warneri; n = 1) of the 20 selected (representing the various staphylococcal species and antibiotypes) isolates were mecA-positive. Furthermore, the tetK gene was detected in nine isolates, six with dfrA, and four were positive for the dfrG gene. One S. aureus was mecA, tetK and dfrG gene positive. The study provides insights on antibiotic-resistant staphylococci from a non-clinical setting and highlights the need for active surveillance to understand the burden of antimicrobial resistance in Nigeria. This is key to improve synergy across the human, animal and environmental health sectors in Nigeria.

The prevalence of drug-resistant and virulent Staphylococcus spp. in a municipal wastewater treatment plant and their spread in the environment

Drug-resistant and pathogenic Staphylococcus spp. strains can reach surface waters and air with wastewater evacuated to the environment. These strains increase the environmental pool of genetic determinants conferring antibiotic resistance and virulence, and constitute a health risk for the employees of wastewater treatment plants (WWTP) who come into daily contact with bioaerosols. The aim of this study was to identify the genetic determinants of drug resistance and virulence in Staphylococcus spp. strains isolated from untreated (UWW) and treated wastewater (TWW), an activated sludge (AS) bioreactor, river water collected upstream and downstream from the wastewater discharge point (URW and DRW), and WWTP employees. All isolates were analysed for the presence of the rpoB gene, and were subjected to clonal analysis by ERIC fingerprinting. As a result, 249 of the 455 analysed isolates were selected for PCR. The presence of the gene encoding nuclease activity in S. aureus (nuc), the methicillin resistance gene (mecA), vancomycin resistance gene (vanA), antiseptic resistance gene (qacA/B) and virulence genes (sasX, pvl, tst1, hla, sec) was determined. The prevalence of nuc, mecA, vanA and qacA/B genes in wastewater and river water was determined by quantitative PCR (qPCR). In the group of strains isolated from wastewater and water samples, 63% were identified as S. aureus, and 20% of the strains carried the vanA gene. The hla virulence gene was present in 80% of the isolates, and the pvl gene was detected in 27% of the isolates. In the group of strains isolated from the employees, 82% were identified as S. aureus, and the presence of vanA and mecA genes was confirmed in 14% and 16% of the isolates, respectively. The most prevalent virulence gene was hla (74%), whereas pvl was observed in 43% of the isolates. The quantitative analysis revealed the highest concentrations of the studied genes in UWW samples, at 2.56x10⁴ gene copies/ml for nuc, 1.18x10³ gene copies /ml for mecA, 8.28x10⁵ gene copies /ml for vanA and 3.83x10⁵ gene copies /ml for qacA/B. Some of analysed genes were identified in the isolates from both URW and DRW samples, as well as in genomic DNA of these samples. These results indicate that wastewater is not effectively treated in the analysed WWTP, which could contribute to the dissemination of antibiotic resistance genes (ARGs) and antibiotic-resistant bacteria (ARB) to the environment. An analysis of the genetic relatedness of selected isolates revealed clusters of strains originating from UWW samples, AS samples and the employees. These observations suggest that ARGs and ARB are transmitted by wastewater bioaerosols to the upper respiratory tract mucosa of the plant's employees, thus increasing their exposure to infectious factors.

Antimicrobial Resistance of Staphylococcus aureus Isolated from Hospital Wastewater in Kermanshah, Iran

Introduction

Hospital wastewater contains highly resistant and virulent bacteria that can spread into the environment. This study was conducted to investigate the antimicrobial resistance of methicillin-resistant Staphylococcus aureus (MRSA) and methicillin-sensitive S. aureus (MSSA) in raw and treated hospital wastewater.

Methods

During a three-month period, 40 sewage samples were collected from the hospital sewage (Kermanshah, Iran), and S. aureus were identified using culture and biochemical tests. MRSA was detected by resistance to cefoxitin. Antibiotic resistance (AR) was determined using disk diffusion according to the Clinical and Laboratory Standards Institute (CLSI) in 20 MSSA (10 raw and 10 treated sewage) and 40 MRSA isolates (20 raw and 20 treated sewage). The antimicrobial resistance genes (ARGs) were determined by PCR.

Results

Eleven and eight percent of the isolates were MRSA in raw and treated sewage samples, respectively. Out of 60 isolates, 59 (98%) were multidrug resistant (MDR). The most common ARGs were mecA (raw=100%, treated=100%), aacA-D (raw=100%, treated=85%) and tetK (raw =95%, treated =45%) in MRSA, while the tetM gene was the most abundant gene (raw=50%, treated=80%) in MSSA. None of isolates (n=60) was positive for the vanB gene. MSSR (n=20) had the highest level of resistance against penicillin (100%), clindamycin (raw=90%, treated=90%), azithromycin (raw=80%, treated=90%). All MRSA isolates (n=40,100%) in both raw and treated sewage samples were non-susceptible to penicillin, oxacillin and azithromycin. There was no significant difference in the frequency AR and ARGs between raw and treated sewage samples (p>0.05).

Conclusion

The results indicated a high frequency of MDR and ARGs in both raw and treated sewage isolates which could be released into the environment through sewage system and pose a serious threat to public health. Hospital wastewater treatment processes should be improved in order to prevent the dissemination of the most resistant strains of S. aureus.

Occurrence of Staphylococcus spp. and investigation of fecal and animal viral contaminations in livestock, river water, and sewage from Tunisia and Romania

The objective of this study was to determine the occurrence of Staphylococcus spp., Escherichia coli, somatic coliphages, F-specific RNA bacteriophages, hepatitis E virus (HEV), and bovine enterovirus (BEV) in fecal and water samples. The occurrence of Staphylococcus spp. was investigated in treated wastewater samples collected from slaughterhouse of Tunisia. Results showed that Staphylococcus spp. were detected in the totality of collected samples with an average mean of 5.44 Log₁₀ (CFU/100 ml). Regarding fecal indicator bacteria, E. coli was detected in the totality of water samples and was more abundant in Tunisian samples than in samples collected from Romania (P < 0.05). Concerning somatic coliphages and F-specific RNA bacteriophages used as viral indicators, they were detected in all raw and treated wastewaters. Bovine enterovirus (BEV) was detected in 20.1% and 28% of bovine stool samples collected from Tunisia and Romania, respectively. BEV was also detected in 60% of porcine stool samples from Romania. BEV was absent in all treated sewage samples. HEV was detected in raw sewage and bovine fecal sample from Romania with low occurrence and none sample from Tunisia was positive. This study may give us an insight into the monitoring of water quality in Tunisia and Romania.

Multi-drug resistance traits of methicillin-resistant Staphylococcus aureus and other Staphylococcal species from clinical and environmental sources

Multi-drug resistance traits of Staphylococcus species especially methicillin-resistant Staphylococcus aureus (MRSA) in the clinical settings are well established. Of environmental concern is hospital effluents discharging into wastewaters. This article investigated the prevalence and detection of antibiotic resistance genes in Staphylococcus species from clinical and environmental sources in Ile-Ife, Nigeria. Standard culture-based and molecular protocols were used. Seventy-six (27 clinical, 14 hospital effluent and 35 environmental) Staphylococcus isolates were recovered: 56.58% were coagulase-negative and 43.42% coagulase-positive (S. aureus). For the clinical isolates, 10, 6, 4, 4 and 1 were isolated from urine, skin, wounds, blood and pus, respectively. Isolates were resistant to methicillin and amoxycillin (91.7%), cloxacillin (88.0%), ciprofloxacin (84.0%), ofloxacin (83.3%), azithromycin (78.0%), ceftazidime (76.0%), gentamycin (75.0%), cefuroxime (75.0%) and erythromycin (72.0%). Nearly, all isolates (90.8%) had multiple antibiotic resistance (MAR) index >0.2. Overall MAR indices for Staphylococcus species isolated from the clinical, hospital effluent and environmental wastewaters were relatively similar (0.482; 0.500; 0.435). mecA, nuc and luk-pvl genes were detected in S. aureus, while mecA was detected in S. arlettae, S. sciuri, S. cohnii, S. epidermidis and S. saprophyticus. This study informs on the potential contamination of environmental waters downstream from hospitals and possible impacts that this could have on human and animal health.

Genetic characterisation of staphylococci of food-producing animals in Senegal. PVL detection among MSSA

Background

Food-producing animals can be a vehicle for staphylococcal species as well as their virulence and antimicrobial resistance genes. This work aimed to analyse the diversity of staphylococcal species in food-producing animals in Dakar/Senegal, and to determine the antimicrobial resistance phenotype/genotype and virulence factors of recovered isolates. Nasal samples of 149 cows and 199 chickens (348 animals) were collected from one slaughterhouse and a local market respectively, and were inoculated on selective media for staphylococci recovery. For S. aureus isolates, molecular typing (spa-type, MLST) was performed by PCR/sequencing, and the presence of 27 virulence genes (exfoliative and toxic shock toxins, PVL, haemolysins and enterotoxins) as well as the gene scn were analysed by PCR. Susceptibility to twelve antibiotics was studied by disc-diffusion method for all staphylococci; the resistance genes involved were screened by PCR.

Results

Staphylococcus spp. was present in 3 and 26.8% of chicken and cow nasal samples, respectively. Seven S. aureus isolates and forty isolates of other staphylococcal species were identified. S. aureus isolates were recovered from cow (n = 6) and chicken (n = 1) samples, belonging to four genetic lineages: t084/ST15 (n = 1); t10579/ST291 (n = 3); t355, t4690/ST152 (n = 2); and t6618/ST6 (n = 1). All S. aureus were methicillin-susceptible, penicillin-resistant (blaZ), and two of them were also tetracycline-resistant [tet(K)]. All the isolates carried at least one of the virulence genes tested. The PVL genes were detected in three ST15 and ST152 isolates. They all harboured haemolysins encoding genes and lacked the scn gene. The other staphylococci recovered were S. sciuri (n = 16), S. simulans (n = 11), S. hyicus (n = 5), S. haemolyticus (n = 4), S. chromogenes (n = 3), and S. hominis (n = 1); they were all methicillin-susceptible and 27.5% tetracycline-resistant [tet(K) and tet(L)].

Conclusions

A low prevalence of S. aureus was detected among food-producing animals, all susceptible to methicillin. However, the presence of virulence genes (lukF/lukS-PV, eta, tst, sea and see) is worrisome to the extent that they could be transferred to derived food and therefore, to humans.

High frequency of coagulase-positive staphylococci carriage in healthy wild boar with detection of MRSA of lineage ST398-t011

The objective of this study was to determine the frequency and diversity of coagulase-positive staphylococci (CoPS) in nasal samples of healthy wild boar, to study their resistance phenotypes/genotypes and to check the occurrence of the MRSA-ST398. Nasal samples of 371 wild boars were collected in Spain for staphylococci and MRSA recovery. Staphylococci identification was performed by matrix-assisted laser desorption/ionization time of flight mass spectrometry (MALDI-TOF). The susceptibility to 11 antimicrobials was tested by disc-diffusion and the presence of resistance genes by PCR. Molecular typing and virulence factors determination were carried out by PCR and sequencing. The rate of CoPS carriage (Staphylococcus aureus, Staphylococcus hyicus and Staphylococcus pseudintermedius) in wild boar was of 17.8% (13.7%, 2.7% and 1.6%, respectively). Susceptibility to all tested antimicrobials was shown in 74.5% of S. aureus and one strain was MRSA [lineage ST398-t011-agrI, carrying blaZ, mecA, tet(M) and tet(K) genes]. A total of 22 spa-types and 17 STs were detected among S. aureus, including: ST398/CC398 (n = 1), ST2328-ST133/CC133 (n = 20), ST425/CC425 (n = 7), ST5/CC5 (n = 5), ST1/CC1 (n = 3), ST130/CC130 (n = 2) and ST88/CC88 (n = 1). Two spa-types (t02, t15) and four STs (ST455, ST796, ST797, ST798) were detected among the six S. pseudintermedius isolates recovered, and all of them carried the lukF/S-I and siet virulence genes. All S. hyicus isolates were susceptible to antimicrobials tested.

Antimicrobial Resistance in Bacterial Pathogens and Detection of Carbapenemases in Klebsiella pneumoniae Isolates from Hospital Wastewater

During a six-month period (October 2017–March 2018), the prevalence and susceptibility of important pathogenic bacteria isolated from 12 hospital raw sewage samples in North Western Greece was investigated. The samples were analyzed for methicillin-resistant Staphylococcus aureus (MRSA), vancomycin-resistant enterococci (VRE), extended-spectrum beta-lactamase (ESBL) producing Escherichia coli, carbapenemase-producing Klebsiella pneumoniae (CKP), and multidrug-resistant Pseudomonas aeruginosa. Antimicrobial susceptibility testing was performed using the agar diffusion method according to the recommendations of the Clinical and Laboratory Standards Institute. The diversity of carbapenemases harboring K. pneumoniae was examined by two phenotyping screening methods (modified Hodge test and combined disk test), a new immunochromatographic rapid assay (RESIST-4 O.K.N.V.) and a polymerase chain reaction (PCR). The results demonstrated the prevalence of MRSA, vancomycin-resistant Staphylococcus aureus (VRSA), VRE, and CKP in the examined hospital raw sewage samples. In addition, the aforementioned methods which are currently used in clinical laboratories for the rapid identification and detection of resistant bacteria and genes, performed sufficiently to provide reliable results in terms of accuracy and efficiency.

Zwitterionic Nanocellulose-Based Membranes for Organic Dye Removal

The development of efficient and environmentally-friendly nanomaterials to remove contaminants and pollutants (including harmful organic dyes) ravaging water sources is of major importance. Herein, zwitterionic nanocomposite membranes consisting of cross-linked poly(2-methacryloyloxyethyl phosphorylcholine) (PMPC) and bacterial nanocellulose (BNC) were prepared and tested as tools for water remediation. These nanocomposite membranes fabricated via the one-pot polymerization of the zwitterionic monomer, 2-methacryloyloxyethyl phosphorylcholine, within the BNC three-dimensional porous network, exhibit thermal stability up to 250 °C, good mechanical performance (Young's modulus ≥ 430 MPa) and high water-uptake capacity (627%-912%) in different pH media. Moreover, these zwitterionic membranes reduced the bacterial concentration of both gram-positive (Staphylococcus aureus) and gram-negative (Escherichia coli) pathogenic bacteria with maxima of 4.3- and 1.8-log CFU reduction, respectively, which might be a major advantage in reducing or avoiding bacterial growth in contaminated water. The removal of two water-soluble model dyes, namely methylene blue (MB, cationic) and methyl orange (MO, anionic), from water was also assessed and the results demonstrated that both dyes were successfully removed under the studied conditions, reaching a maximum of ionic dye adsorption of ca. 4.4-4.5 mg g-1. This combination of properties provides these PMPC/BNC nanocomposites with potential for application as antibacterial bio-based adsorbent membranes for water remediation of anionic and cationic dyes.

High diversity of coagulase negative staphylococci species in wild boars, with low antimicrobial resistance rates but detection of relevant resistance genes

This work was focused to determine the prevalence and the species diversity of coagulase-negative staphylococci (CoNS) in wild boars, and to study their antimicrobial resistance phenotype and genotype. Nasal samples of 371 wild boars from six Spanish regions were collected for CoNS recovery. The identification was performed by MALDI-TOF mass-spectrometry. Antimicrobial susceptibility for eight antimicrobial agents was studied by disc-diffusion method and the presence of 31 antimicrobial resistance genes by PCR. CoNS were detected in nasal samples of 136/371 animals tested (36.6%), and 161 isolates were obtained (1-3/animal); a high diversity of species was found (n = 17), with predominance of S. sciuri (n = 64), S. xylosus (n = 21) and S. chromogenes (n = 17). Among CoNS isolates, 22.4% showed resistance to at least one antimicrobial tested. Tetracycline-resistance phenotype was the most frequently detected (10.5%), generally mediated by tet(K) gene [associated or not with tet(L)]. Other relevant resistance genes were identified including unusual ones [mecA, erm(B), erm(F), mphC, erm(43), msr(A)/msr(B), lnu(A), dfrG, fexA, and cat_pC221]. This is the first study in which CoNS isolates from wild boars are analysed. The knowledge of antimicrobial phenotype and genotype of CoNS in natural ecosystems is highly important since these staphylococcal species can act as vectors of relevant antimicrobial resistance mechanisms.

Investigating the potential use of an Antarctic variant of Janthinobacterium lividum for tackling antimicrobial resistance in a One Health approach

The aim of this paper is to describe a new variant of Janthinobacterium lividum - ROICE173, isolated from Antarctic snow, and to investigate the antimicrobial effect of the crude bacterial extract against 200 multi-drug resistant (MDR) bacteria of both clinical and environmental origin, displaying various antibiotic resistance patterns. ROICE173 is extremotolerant, grows at high pH (5.5–9.5), in high salinity (3%) and in the presence of different xenobiotic compounds and various antibiotics. The best violacein yield (4.59 ± 0.78 mg·g⁻¹ wet biomass) was obtained at 22 °C, on R2 broth supplemented with 1% glycerol. When the crude extract was tested for antimicrobial activity, a clear bactericidal effect was observed on 79 strains (40%), a bacteriostatic effect on 25 strains (12%) and no effect in the case of 96 strains (48%). A very good inhibitory effect was noticed against numerous MRSA, MSSA, Enterococci, and Enterobacteriaceae isolates. For several environmental E. coli strains, the bactericidal effect was encountered at a violacein concentration below of what was previously reported. A different effect (bacteriostatic vs. bactericidal) was observed in the case of Enterobacteriaceae isolated from raw vs. treated wastewater, suggesting that the wastewater treatment process may influence the susceptibility of MDR bacteria to violacein containing bacterial extracts.

Stable oligonucleotide-functionalized gold nanosensors for environmental biocontaminant monitoring

The global propagation of environmental biocontaminants such as antibiotic resistant pathogens and their antibiotic resistance genes (ARGs) is a public health concern that highlights the need for improved monitoring strategies. Here, we demonstrate the environmental stability and applicability of an oligonucleotide-functionalized gold nanosensor. The mecA ARG was targeted as model biocontaminant due to its presence in clinically-relevant pathogens and to its emergence as an environmental contaminant. mecA-specific nanosensors were tested for antibiotic resistance gene (ARG) detection in ARG-spiked effluent from four wastewater treatment plants (WWTPs). The mecA-specific nanosensors showed stability in environmental conditions and in high ionic strength ([MgCl₂]<50mM), and high selectivity against mismatched targets. Spectrophotometric detection was reproducible with an LOD of 70pM (≈4×10⁷genes/μL), even in the presence of interferences associated with non-target genomic DNA and complex WWTP effluent. This contribution supports the environmental applicability of a new line of cost-effective, field-deployable tools needed for wide-scale biocontaminant monitoring.

Aquatic animals promote antibiotic resistance gene dissemination in water via conjugation: Role of different regions within the zebra fish intestinal tract, and impact on fish intestinal microbiota

The aqueous environment is one of many reservoirs of antibiotic resistance genes (ARGs). Fish, as important aquatic animals which possess ideal intestinal niches for bacteria to grow and multiply, may ingest antibiotic resistance bacteria from aqueous environment. The fish gut would be a suitable environment for conjugal gene transfer including those encoding antibiotic resistance. However, little is known in relation to the impact of ingested ARGs or antibiotic resistance bacteria (ARB) on gut microbiota. Here, we applied the cultivation method, qPCR, nuclear molecular genetic marker and 16S rDNA amplicon sequencing technologies to develop a plasmid-mediated ARG transfer model of zebrafish. Furthermore, we aimed to investigate the dissemination of ARGs in microbial communities of zebrafish guts after donors carrying self-transferring plasmids that encode ARGs were introduced in aquaria. On average, 15% of faecal bacteria obtained ARGs through RP4-mediated conjugal transfer. The hindgut was the most important intestinal region supporting ARG dissemination, with concentrations of donor and transconjugant cells almost 25 times higher than those of other intestinal segments. Furthermore, in the hindgut where conjugal transfer occurred most actively, there was remarkable upregulation of the mRNA expression of the RP4 plasmid regulatory genes, trbBp and trfAp. Exogenous bacteria seem to alter bacterial communities by increasing Escherichia and Bacteroides species, while decreasing Aeromonas compared with control groups. We identified the composition of transconjugants and abundance of both cultivable and uncultivable bacteria (the latter accounted for 90.4%-97.2% of total transconjugants). Our study suggests that aquatic animal guts contribute to the spread of ARGs in water environments.

Staphylococcus aureus isolated from wastewater treatment plants in Tunisia: occurrence of human and animal associated lineages

The objective was to characterize Staphylococcus aureus isolated from two wastewater treatment plants (WWTPs) located in Tunis City (Tunisia), during the period 2014-2015. Genetic lineages, antibiotic resistance mechanisms and virulence factors were determined for the recovered isolates. S. aureus isolates were recovered from 12 of the 62 wastewater samples tested (19.35%), and one isolate/sample was characterized, all of them being methicillin-susceptible (MSSA). Six spa types (t587, t674, t224, t127, t701 and t1534) were found among the 12 isolates, and the spa-t587, associated with the new sequence type ST3245, was the most predominant one (7 isolates). The remaining isolates were assigned to five clonal complexes (CC5, CC97, CC1, CC6 and CC522) according to the sequence-type determined and/or the spa-type detected. S. aureus isolates were ascribed to agrI (n = 3), agrII (n = 7) and agrIII (n = 1); however, one isolate was non-typeable. S. aureus showed resistance to (number of isolates): penicillin (12), erythromycin (7), tetracycline (one) and clindamycin (one). Among the virulence factors investigated, only one isolate harboured the tst gene, encoding the TSST-1 (toxic shock syndrome toxin 1). Despite the low number of studied isolates, the present study reports the occurrence of both human- and animal-associated S. aureus clonal complexes in WWTPs in Tunisia.

Prevalence, Virulence Genes, Antimicrobial Susceptibility, and Genetic Diversity of Staphylococcus aureus from Retail Aquatic Products in China

Staphylococcus aureus is an important food-borne opportunistic pathogen that frequently causes severe blood and tissue infections or even fatal illnesses. Although S. aureus has been extensively studied in livestock and poultry foods in China, limited information has been reported in aquatic products. Accordingly, in this study, we aimed to characterize S. aureus in aquatic products purchased from retail markets in China. In total, 320 aquatic food samples were collected from 32 provincial capitals in China. The results showed that 119 samples (37.2%, 119/320) were positive for S. aureus by both qualitative and quantitative analyses. The contamination levels of 78.2% of samples ranged from 0.3 to 10 MPN/g, and six samples exceeded 110 MPN/g. A total of 119 S. aureus isolates from positive samples were selected to evaluate virulence factors, antibiotic resistance, and molecular characteristics. All S. aureus isolates were evaluated for the presence of 11 virulence genes by multiplex polymerase chain reaction, and α-hemolysin (hlα, 84.9%), fibronectin-binding protein A (fnbA, 79.0%), S. aureus enterotoxin E (see, 53.8%), and Panton-Valentine leucocidin (pvl, 50.4%) were identified as the major genes. These genes formed 56 different profiles, with the major profile identified as pvl-hlα-fnbA (28.6%). The antimicrobial susceptibility of all isolates was analyzed through the disk diffusion method, and the results showed high resistance to β-lactams, macrolides and tetracyclines, but susceptibility to linezolid and vancomycin. In addition, 26 sequence types (STs) were obtained via multilocus sequence typing, including seven novel STs, among which ST1 (20.2%), ST15 (18.5%), and ST188 (13.4%) were the most common STs. All the isolates were mecC negative, but nine isolates carrying mecA were evaluated by staphylococcal cassette chromosome mec (SCCmec) typing, all of which were SCCmecIII or SCCmecIV types. Isolates of SCCmecIII showed a high prevalence and were multidrug resistant. Our results showed that aquatic products could be a vehicle for transmission of virulence genes and multidrug-resistant S. aureus, representing a potential public health risk. The STs identified in this study indicated the genetic diversity of S. aureus, thereby providing important basic data for the dissemination of S. aureus in aquatic products.

Diversity of species and antimicrobial resistance determinants of staphylococci in superficial waters in Spain

The objectives were to determine the presence and diversity of staphylococcal species in surface waters in La Rioja region (Spain), and to characterize recovered isolates. Staphylococci were detected in 42 of 47 evaluable samples, and 72 isolates were obtained, of which 13 were coagulase-positive (CoPS) and 59 were coagulase-negative (CoNS). Twelve CoPS were identified as S. aureus and typed as follows (number of strains): t002/t502/ST5 (four), t10668/ST425 (one), t10712//ST1643 (one), t843/ST130 (one), t10855/ST2461 (one), t3369/ST2657 (one), t1166/ST133 (one), t8083/ST2049 (one) and t045/ST2460 (one); and one as S. pseudintermedius ST147. Virulence genes tst, cna and lukS/F-I were detected, and one strain showed the immune evasion cluster type F. Regarding CoNS, 12 different species were recovered (number of strains): S. epidermidis (11), S. vitulinus (10), S. sciuri (nine), S. fleurettii (seven), S. lentus (six), S. simulans (five), S. xylosus (four), S. chromogenes (two), S. hominis (two), and S. equorum, S. succinus and S. warneri (one each). Fourteen CoNS isolates presented a multidrug resistance phenotype, with the following resistance genes: blaZ, mecA, fusB, fusC, erm(C), mph(C), erm(A), msr(A)/(B), mph(C), ant(4')-Ia, tet(K), tet(L), cat_pc194 and str The high diversity of staphylococcal species, as well as multiple resistance and virulence genes, highlights the importance of surface waters as a temporary reservoir and source of transmission.