High Multiple Antibiotic Resistance Research Articles

Plastic Debris in the Aquatic Environment: An Emerging Substratum for Antimicrobial Resistant (AMR) Biofilms.

Plastic pollution has quadrupled over the past years and has become a global concern due to its direct impact on life forms. The present study analysed whether the plastic debris in aquatic environments could act as the substratum for the antimicrobial-resistant (AMR) bacteria to form biofilm for survival. We have collected various plastic debris (n = 32) from six sites of the Periyar River, the drinking water source for the entire city and one of the most polluted rivers in Kerala (India). The chemical composition of plastics was screened via FTIR analysis and found that they comprised two types, viz., polyethylene and polypropylene. Bacteria isolated from the samples were screened for the AMR characteristics towards eight different classes of antibiotics. All isolates showed 100% resistance towards colistin and obtained the MAR index value of 0.1-0.4 range. Six representative bacterial isolates with high multiple antibiotic resistance (MAR) index were selected and identified by 16sRNA sequencing as Lysinibacillus mangiferihumi, Bacillus pumilus, Bacillus safensis, Bacillus cereus, Bacillus altitudins and Bacillus pumilus. In vitro biofilm formation was experimented on the purchased plastic samples in artificial media and river water using two selected strains, Bacillus pumilus and Bacillus cereus. Significant variations were observed in biofilm growth in different media (P < 0.05) regardless of plastic types (P > 0.05). The extracellular polymeric substances (EPS) and the characteristic holes on the surface morphology were visualized in SEM analysis, thus indicating the conditioning of the plastics by the isolates for biofilm formation.

Environmental reservoirs of multidrug-resistant pseudomonads in a geographical location in Kenya with high community-acquired infections

Background Pseudomonads are gram negative bacteria and readily form biofilms in the environment, allowing long-term colonization and persistence in sinks, water systems. They pose a risk of life-threatening opportunistic infections in immune-compromised individuals. MDR strains, make treatment increasingly difficult. Environmentally persistent MDR strains are typically problematic within healthcare facilities, however, data on MDR pseudomonad reservoirs in settings with community-acquired infections to inform preventive interventions, in resource-constrained settings is scarce. Here, we determined reservoirs and antibiotic susceptibility of Pseudomonas species in water sources in Kisumu County, Kenya with reported high levels of community acquired pseudomonad infections. Methods We adopted a cross-sectional design, randomly collecting 297 samples from tap heads, sinks, tanks, vendor and household storage containers in six selected sub-locations and one hospital (KCRH). Standard microbiological procedures were used for identification and AST of the isolates. Results We isolated Pseudomonads from 14.1% of the samples collected, predominantly from the community 10.4%. Seven different pseudomonads were identified, with Pseudomonas aeruginosa predominating 6.7% overall, in the community samples 5.7%, and among isolates from water tanks 21.4%. Pseudomonad isolates were 62% non-susceptible to piperacillin, 57% to tigecycline, 24% meropenem, 21% cefepime, 19% levofloxacin and 14% colistin. Carbapenem resistance was mainly detected in P. aeruginosa 80% (8/10) from Milimani sub-location 75% (6/8). 45% of the isolates recovered were MDR, mainly community-associated carbapenem-resistant P. aeruginosa (CRPA) 42%, strains susceptible to colistin. The MDR pseudomonads exhibited high multiple antibiotic resistance indices, ranging from 0.43 to 1. Conclusion This study reveals a higher prevalence of MDR pseudomonads, including CRPA strains in community water sources. These potential conduits of drug resistance present a critical public health threat, especially among immunocompromised. Regular cleaning of water storage facilities, water treatment and implementation of antimicrobial stewardship programs, are required to prevent a rise in AMR and eliminate the environmental reservoirs that put the vulnerable populations at risk.

Prevalence of diverse antimicrobial resistance genes and bacteria in sewage treatment plant-derived sludge environment.

Antimicrobial resistance (AMR) contamination in the environment is one of the most significant worldwide threats of the 21st century. Since sludge is heavily exposed to diverse contaminants, including pharmaceuticals, the inhabitant bacterial population is expected to exhibit resistance to antimicrobial agents. In this study, sewage treatment plant (STP) sludge samples were analyzed to assess the antibiotic-resistant bacterial population, abundance of AMR genes (ermF, qnrS, Sul1, blaGES, blaCTX-M, and blaNDM), and mobile genetic elements (intl1 and IS26). Out of 16, six bacterial isolates exhibited resistance to 13 antibiotics with a high multiple antibiotic resistance index (MARI) (0.93) and high metal tolerance. Quantitative polymerase chain reaction showed the abundance of target genes ranging from 6.6×103 to 6.5×108 copies g-1 sludge. The overall outcome reveals that STP sludge comprised varied multidrug-resistant bacterial populations. It will give insights into the functions of heavy metals and biofilm development in the selection and spread of AMR genes and the associated bacteria. Therefore, the application of sludge needs proper screening for AMR and metal contamination prior to its countless applications. This study will contribute immensely to the risk analysis of STP effluents on environmental health, including control of AMR transmission.

Isolation and Identification of Antibiotic-Susceptible Bacteria from Abattoir Effluent in Port Harcourt, Rivers State, Nigeria

Abattoir environment can become a significant reservoir for antibiotic resistance bacteria, particularly in abattoirs that do not treat their waste before discharge. This study seeks to verify the antibiotics susceptibility profile of bacteria isolated from abattoir wastewater in Port Harcourt, River State, Nigeria. The bacteria were isolated from the wastewater using a standard plating technique. The antibiotics sensitivity pattern of all bacterial isolates was determined by the Kirby-Bauer disk diffusion method. Isolates with high multiple antibiotic resistance (MAR) index (≥0.5) were screened for genes for pathogenicity (icaC, adhesion gene) and antibiotic resistance (QnrA gene). The abattoir wastewaters were contaminated by bacteria resistant to no less than two of the antibiotics experimented with (MAR index range, 0.2-1.0). The isolates were identified as Acinetobacter brisouii, Bacillus altitudinis, Bacillus stratosphericus and Priestia flexa. Among these isolates, 2(50.0%) harboured the QnrA gene while 3(75.0%) harboured the icaC gene. The findings underscore the importance of abattoir wastewater as an environmental flashpoint for antibiotic resistance. Detection of bacteria with multiple antibiotic resistance in abattoir wastewater would inform cautious use of antibiotics, to check the spread of antibiotic resistance emanating from this source.

A STUDY OF OCCURRENCE OF ANTIBIOTIC RESISTANCE REPORTED AGAINST STAPHYLOCOCCUS AUREUS IN THE DEPARTMENT OF MICROBIOLOGY IN A TERTIARY CARE HOSPITAL IN HAPUR

Objective: The aim of the study is to evaluate the occurrence of antibiotic resistance reported against Staphylococcus aureus in the department of microbiology in a tertiary care hospital in Hapur. Methods: Urine, pus, blood, throat swab, and sputum samples of 15–60-year-old patients were collected and cultured. 100 samples were selected where S. aureus had grown. Bacteria were identified and the antimicrobial sensitivity testing was carried out. Results: The strain of resistant bacteria originates from an environment where several antibiotics are used. The bacteria were seen to be resistant frequently to 2–5 antibiotics. This indicates earlier exposure of the isolated bacteria to these drugs. Conclusion: The high multiple antibiotic resistance is identified in this study and it is necessary to make changes to national antibiotic policy.

Carbapenem-resistant Acinetobacter baumannii infections: Antimicrobial resistance patterns and risk factors for acquisition in a Kenyan intensive care unit

ObjectivesMultidrug-resistant (MDR) Acinetobacter baumannii (AB), especially carbapenem-resistant (CR) strains, presents a significant challenge in intensive care units (ICUs) but surveillance data in many resource-constrained countries is inadequate. Here, we determined the prevalence of MDRAB and risk factors for infection and mortality in ICU-admitted patients. MethodsA cross-sectional study among 132 consecutive patients between July 2019 and July 2020, with infected patients followed for 30 days from sample collection to ICU discharge/death. Blood, urine, and tracheal aspirate samples were processed following the standard bacteriological procedures. Isolate identity and antimicrobial susceptibility were elucidated by VITEK 2 Compact system. ResultsThe prevalence of MDRAB was 22.7% (30/132), mostly from urine samples (12.1%, 16/132), and dominated by CRAB (83.3%) that were colistin-nonresistant and exhibited high multiple antibiotic resistance indices, ranging from 0.64-0.91. Risk factors for infection were occupation (adjusted odds ratio = 4.41, P = 0.016) and interhospital referral status (adjusted odds ratio = 0.14, P = 0.001). ICU mortality was 20% (6/30). ConclusionOur findings underpin the need for strict adherence to and evaluation of infection prevention and control, and continuous surveillance of CRAB in ICU, especially among the risk groups, in the current study setting and beyond.

Prevalence of Aminoglycoside Resistance Genes in Clinical Isolates of Pseudomonas aeruginosa from Taif, Saudi Arabia-An Emergence Indicative Study.

Hospital-acquired infections caused by P. aeruginosa contribute to global distress because of the elevated rates of microbial antibiotic resistance. Aminoglycosides are antipseudomonal agents that are effectively and frequently utilized to eradicate this infection. This current study is a retrospective study investigating plasmid-mediated aminoglycoside resistance by focusing on the prevalence of the genes encoding aminoglycoside-modifying enzymes (AMEs) and 16S rRNA methylase among P. aeruginosa clinical isolates from Taif, Saudi Arabia. A hundred clinical isolates of P. aeruginosa were collected. The isolates were identified from February 2021 to February 2022. Antibiotic susceptibility testing and MICs were determined using (DD) and (BM-MIC) testing, respectively. AMEs and 16S rRNA methylase variants in bacterial isolates were amplified via PCR for genetic detection. A relatively high multiple antibiotic resistance rate corresponding to 10-32% was reported. Eighteen percent of P. aeruginosa isolates were gentamicin-amikacin-tobramycin resistant according to the MIC levels. The aminoglycoside-resistant strains were additionally identified via GyrA gene sequencing. The phylogenic relatedness dendrogram of the sequenced GyrA genes was performed using a neighbor-joining method via MEGAX software version 10.2.6. The most prevalent AME encoding gene was aac(6')-Ib, observed in 94.4% of resistant isolates, while a resistance gene cocktail of [aac(6')-Ib and ant(3″)-I] was a highly frequent combination (27.8%). This study updated the knowledge about aminoglycoside resistance mechanisms in P. aeruginosa, which constitutes an urgent need, especially after the COVID-19 crisis, which was associated with increased antimicrobial use and resistance rates.

Mısır Sidr Balının Antimikrobiyal Aktivitesi ve Antimikrobiyal Ajanlarla Sinerjik Etkisi

Determine the in vitro antibacterial potential activity sidr honey produced in upper Egypt against five references bacterial strains (Gram positive and Gram negative strains) and its synergistic effect with some antimicrobial agents. Material &amp; Methods: fifteen Sidr honey samples were collected from three Governorates in Upper Egypt. Honey samples were diluted and tested against Staphylococcus aureus, Streptococcus agalactiae, Escherichia coli, Klebsiella pneumoniae and Bacillus cereus by agar dilution method. Post determination of the minimum inhibitory concentration (MIC) values, six honey samples were examined for their synergistic action with the ineffective antimicrobial agents. Results: In vitro antimicrobial sensitivity test, all bacterial strains showed multidrug resistance action against the 13 tested antimicrobial agents with high multiple antibiotic resistance (MAR) index, it was ≥ 0.38. All Sidr bee honey samples showing antibacterial activity against the five tested references bacterial strains. All Sidr bee honey samples, showed better synergistic effect with all antimicrobial agents against.

Prevalence of Salmonella in poultry slaughterhouses located in Tripoli, Libya.

Salmonella is a leading cause of severe economic losses in poultry and foodborne illness in humans worldwide. The aim of this study was to determine the prevalence and multidrug resistance of Salmonella Enteritidis (S. Enteritidis) in several chicken abattoirs in Tripoli, Libya. The study includes the South, East, and West regions of Tripoli. Each region was assigned five slaughterhouses. Each chicken slaughterhouse was visited three times to collect samples. Five samples were taken at random from the neck skin, crop, and spleen. The total number of samples collected from all regions was 675. Bacterial isolation and identification, as well as antibiotic sensitivity testing, were performed on these samples. Salmonella spp. was found to be 15% prevalent, and S. Enteritidis was found to be 7% prevalent. The south region of Tripoli had the highest S. Enteritidis (9%), while the west region had the highest Salmonella spp. (22%). Salmonella prevalence increased significantly (p < 0.01) higher in the spleen (13%) as compared with the crop (5%) and neck (7%). Based on bacterial resistance pattern, Salmonella spp. isolated from the spleen had the highest multiple antibiotic resistance (MAR) index of 0.86 in the south region followed by MAR indexes of 0.8 and 0.46 in the West and East, respectively. Isolation of Salmonella from the spleen may indicate chickens' systemic infection and failure to control the most important microbe for public health. Thus, the control measures have to be revised and a national Salmonella control program should be put in place urgently.

Co-Prevalence of Virulence and Pathogenic Potential in Multiple Antibiotic Resistant Aeromonas spp. from Diseased Fishes with In Silico Insight on the Virulent Protein Network.

Aeromonas species exhibit widespread presence in food, poultry, and aquaculture. They are major multi-drug-resistant fish pathogens. This study aims to identify Aeromonas species harbouring virulence genes aerolysin, flagellin, and lipase from diseased fishes of Assam wetlands with association with antibiotic resistance and in vivo pathogenicity. One hundred and thirty-four Aeromonas strains were isolated and thirty representative species identified using genus-specific 16S rRNA gene amplification. A. veronii was most prevalent (53.7%) followed by A. hydrophila (40.2%), A. caviae (4.47%), and A. dhakensis (1.49%). Ninety percent (90%) of strains harboured at least one of the studied virulence genes: aerA (73.3%), lip (46.6%), and flaA (26.6%). The highest multiple antibiotic resistance (MAR) index 0.8 corresponded to A. hydrophila DBTNE1 (MZ723069), containing all the studied genes. The lowest LD50 values (1.6 × 106 CFU/fish) corresponded to isolates having both aerA and lip. β-lactams showed utmost resistance and lowest for aminoglycosides. There was a significant (p < 0.05) Pearson chi-square test of association between the occurrence of virulence and antibiotic resistance. The in silico protein−protein interaction revealed important drug targets, such as σ28 transcription factor, aminoacyl-tRNA synthetase, and diacylglycerol kinase, with significant (p < 0.05) enrichment. This study suggests that fish-isolate Aeromonas strains represent potential threat to aquaculture with subsequent risk of transferring antibiotic resistance to human pathogens.

Occurrence, antimicrobial resistance, virulence, and biofilm formation capacity of Vibrio spp. and Aeromonas spp. isolated from raw seafood marketed in Bangkok, Thailand.

Background and Aim:Bacteria of the genera Vibrio and Aeromonas cause seafood-borne zoonoses, which may have a significant impact on food safety, economy, and public health worldwide. The presence of drug-resistant and biofilm-forming phenotypes in the food chain increases the risk for consumers. This study aimed to investigate the characteristics, virulence, biofilm production, and dissemination of antimicrobial-resistant pathogens isolated from seafood markets in Bangkok, Thailand.Materials and Methods:A total of 120 retail seafood samples were collected from 10 local markets in Bangkok and peripheral areas. All samples were cultured and the Vibrio and Aeromonas genera were isolated using selective agar and biochemical tests based on standard protocols (ISO 21872-1: 2017). The antibiotic susceptibility test was conducted using the disk diffusion method. The presence of hemolysis and protease production was also investigated. Polymerase chain reaction (PCR) was used to determine the presence of the hlyA gene. Furthermore, biofilm formation was characterized by microtiter plate assay and scanning electron microscopy.Results:The bacterial identification test revealed that 35/57 (61.4%) belonged to the Vibrio genus and 22/57 (38.6%) to the Aeromonas genus. The Kirby–Bauer test demonstrated that 61.4% of the isolates were resistant to at least one antibiotic and 45.61% had a high multiple antibiotic resistance index (≥0.2). PCR analysis indicated that 75.44% of the bacteria harbored the hlyA gene. Among them, 63.16% exhibited the hemolysis phenotype and 8.77% showed protease activity. The biofilm formation assay demonstrated that approximately 56.14% of all the isolates had the potential to produce biofilms. The moderate biofilm production was the predominant phenotype.Conclusion:The results of this study provide evidence of the multiple drug resistance phenotype and biofilm formation capacity of Vibrio and Aeromonas species contaminating raw seafood. Effective control measures and active surveillance of foodborne zoonoses are crucial for food safety and to decrease the occurrence of diseases associated with seafood consumption.

Multiple Antibiotic Resistance in Escherichia coli Isolates from Fecal and Water Sources in Laguna Lake, Philippines

Due to the misuse and overuse of antibiotics, antibiotic residues accumulate in natural environments, leading to the development of antibiotic-resistant bacteria (ARBs). The presence of ARBs in bodies of water poses health hazards to the surrounding community. This study focused on Laguna Lake, the largest lake in the Philippines, which serves as a water source for agriculture and domestic purposes. We aimed to detect the presence of antibiotic-resistant Escherichia coli from the lake waters and potential reservoirs of resistance as well as determine the multiple antibiotic resistance (MAR) indices of the isolates. E. coli (n = 450) was isolated from fecal-associated samples (chicken, cow, pig, human, sewage) and water samples (sites in Laguna Lake and selected river tributaries). The isolates were subjected to an antibiotic resistance assay using VITEK 2®. Among the 16 antibiotics tested, the isolates exhibited varying resistance to 14, but complete susceptibility to amikacin and tigecycline was observed. Isolates were most frequently resistant to ampicillin (196/450, 43.6%). Among fecal-associated samples, chicken isolates exhibited the highest MAR index (0.174), whereas samples from Pila River exhibited the highest MAR index (0.152) among water samples. The results of this study demonstrate the presence of multidrug-resistant E. coli in samples collected around Laguna Lake and reveal fecal and sewage sources as potential reservoirs of ARBs in the water body. With this information, the public is urged to use antibiotics responsibly to help mitigate the spread of antibiotic resistance.

Anti-Biofilms’ Activity of Garlic and Thyme Essential Oils against Salmonella typhimurium

Biofilm control by essential oil (EO) application has recently increased to preclude biofilm production on foods and environmental surfaces. In this work, the anti-biofilm effects of garlic and thyme essential oils using the minimum inhibitory concentration (MIC) method against Salmonella typhimurium recovered from different abattoir samples were investigated along with the virulence genes (InvA, SdiA and Stn genes), and the antimicrobial susceptibility profile of S. typhimurium as well. The obtained results revealed that S. typhimurium contaminated abattoir samples to varying degrees. The InvA gene was investigated in all isolates, whereas the SdiA and Stn genes were observed in four and three isolates, respectively. Utilizing the disc diffusion method, S. typhimurium isolates demonstrated substantial resistance to most of the examined antibiotics with a high multiple antibiotic resistance index. S. typhimurium isolates demonstrated biofilm formation abilities to various degrees at varied temperatures levels (4 °C and 37 °C). In conclusion, the obtained samples from the research area are regarded as a potential S. typhimurium contamination source. Furthermore, garlic essential oil (GEO) has more potential to inhibit S. typhimurium biofilm at different sub-minimum inhibitory concentrations as compared to thyme essential oil (TEO). Therefore, these EOs are considered as potential natural antibacterial options that could be applied in food industry.

The High Occurrence of Multidrug-Resistant Salmonella spp. Isolated from Raw Chicken Meat and Contact Surfaces at Wet Market in Malaysia

Post-slaughter processing steps during poultry meat production contribute to Salmonella contamination and may transmit multidrug-resistant Salmonella to chicken meats and contact surfaces. This study was undertaken to identify Salmonella spp. strains isolated from chicken meats and their contact surfaces, and to determine their antibiotic resistance profiles. A total of 20 samples were collected from raw chicken meat and its contact surfaces from a shop in Pasar Chow Kit, Kuala Lumpur. Identification of presumptive Salmonella colonies was conducted by using biochemical tests and multiplex polymerase chain reaction (PCR). Antibiotic susceptibility test was conducted by using Kirby-Bauer disk diffusion method against 11 antibiotics. Salmonella enterica Group I was only detected in seven samples. The antibiogram testing showed that all the seven Salmonella isolates (100%) were multidrug-resistant and all isolates were resistant to penicillin, chloramphenicol, erythromycin, and tetracycline. Resistance towards trimethoprim-sulfamethoxazole, amoxicillin and ampicillin was observed in four isolates. However, sensitivity was recorded for cephalexin, cefoxitin, cefotaxime, and ceftriaxone in six isolates. The highest multiple antibiotic resistance (MAR) index of 1.00 (resistance to all eleven antibiotics tested) was observed in one isolate (P2) while the lowest MAR index of 0.36 (resistance to four antibiotics tested) was observed in three isolates (CB, M2 and M3). Our results demonstrated that raw chicken and meat contact surface were a source of multidrug-resistant Salmonella and can contribute to significant health concern in Malaysia. Stringent hygienic procedure during chicken meat processing should be therefore be practised.

Microbiological Quality Assessment and Identification of Antibiotic Resistant Bacteria at Different Stages of the Milk Supply Chain in Dhaka City of Bangladesh

Aims: Milk works as an excellent medium for bacterial growth and can turn into a fatal source of food borne diseases when consumed without pasteurization. This study was carried out to examine the microbiological quality of milk from three different points of milk supply chain to investigate whether the dairy stakeholders are maintaining the consumer safety or not.&#x0D; Study Design: A cross sectional study&#x0D; Place and Duration: The study took place at the Food Microbiology lab of Institute of Nutrition and Food Science, University of Dhaka from November 2019 to February 2020.&#x0D; Methodology: A total of 60 samples were studied including raw milk from collection centers, unpackaged pasteurized milk from processing plants and packaged pasteurized milks from retail shops. After carrying out the microbiological analysis the samples were examined for determining the total bacterial count (TBC) and total coliform count (TCC). Antibiotic susceptibility test was done using disk diffusion assay and detection of virulent gene in Salmonella spp. was done by Polymerase Chain Reaction (PCR) using specific invA primer.&#x0D; Results: The results revealed that all raw milk samples were substandard in terms of TBC and TCC and pasteurized milks from processing plants maintained the standard quality. Importantly, packaged pasteurized milk samples from retail shops had high TBC (&gt;4.0× 104 CFU/mL) and TCC (1.2×103 CFU/mL) containing Pseudomonas, Micrococcus, Streptococcus, Salmonella, Proteus, Staphylococcus, Bacillus and E. coli. Bacteria like Salmonella (75%), Proteus (62.5%) and Vibrio (62.5%) possessed high Multiple Antibiotic Resistance (MAR) index and showed resistance towards antibiotics namely Ampicillin, Amoxicillin, Erythromycin and Colistin. Through further molecular analysis we detected invA virulent gene one of the Salmonella isolates which was collected from the pasteurized milk samples of the retail shops.&#x0D; Conclusion: High bacterial load in raw milk and packaged pasteurized milk indicate that the milk we consume is substandard in microbiological quality. Precautionary measurements and careful processing of milk may reduce the prevalence of microbiological contamination in the milk supply chain.

Antibiotic resistance pattern of Pseudomonas spp. from patients in a tertiary hospital in South-West Nigeria.

Pseudomonads constitute critical agents of opportunistic infections in hospital settings particularly in immunocompromised patients and Pseudomonas aeruginosa is a major flagship member of these infectious agents. This study assessed the distribution of Pseudomonas spp. associated with infections in patients and their antibiotic resistance patterns as part of an antibiotic stewardship intervention program and resistance surveillance. One hundred and fifty Pseudomonas spp. from different clinical specimens were obtained from the Obafemi Awolowo University Teaching Hospitals Complex Ile-Ife. Culture was carried out on MacConkey and blood agar while phenotypic characterization was done by Gram staining, oxidase, and catalase test. Species identification was done using MICROBACTTM 24E bacterial identification kit and confirmed by 16S rDNA polymerase chain reaction (PCR) assay. Antibiotic susceptibility testing to eight antibiotics in four classes was done. Pseudomonas aeruginosa was the most frequently occurring species (96.0%); P. putida (2.67%) and P. fluorescens (0.67%) were also identified as well as an isolate of Burkholderia pseudomallei (0.67%). The highest resistance rate among isolates was observed towards gentamicin (35.4%); piperacillin/tazobactam was the most active antibiotic. Multidrug-resistant (MDR) strains constituted 12.8% of the isolates and most MDR strains also displayed a high multiple antibiotic resistance index (MAR). Pseudomonas aeruginosa is emerging as a highly MDR pathogen in our hospital setting. This calls for the establishment of a surveillance system and antimicrobial stewardship programme in place. Furthermore, we propose a review of the current antibiotics prescription policy, and infection control programmes (ICPs) if we must control the spread of MDR-P. aeruginosa in this environment.

Identification, antibiotic resistance, and virulence profiling of Aeromonas and Pseudomonas species from wastewater and surface water.

Aquatic environments are hotspots for the spread of antibiotic-resistant bacteria and genes due to pollution caused mainly by anthropogenic activities. The aim of this study was to evaluate the impact of wastewater effluents, informal settlements, hospital, and veterinary clinic discharges on the occurrence, antibiotic resistance profile and virulence signatures of Aeromonas spp. and Pseudomonas spp. isolated from surface water and wastewater. High counts of Aeromonas spp. (2.5 (± 0.8) - 3.3 (± 0.4) log10 CFU mL-1) and Pseudomonas spp. (0.6 (± 1.0) - 1.8 (± 1.0) log10 CFU mL-1) were obtained. Polymerase chain reaction (PCR) and MALDI-TOF characterization identified four species of Aeromonas and five of Pseudomonas. The isolates displayed resistance to 3 or more antibiotics(71% of Aeromonas and 94% of Pseudomonas). Aeromonas spp. showed significant association with the antibiotic meropenem (χ2 = 3.993, P < 0.05). The virulence gene aer in Aeromonas was found to be positively associated with the antibiotic resistance gene blaOXA (χ2 = 6.657, P < 0.05) and the antibiotic ceftazidime (χ2 = 7.537, P < 0.05). Aeromonas recovered from both wastewater and surface water displayed high resistance to ampicillin and had higher multiple antibiotic resistance (MAR) indices close to the hospital. Pseudomonas isolates on the other hand exhibited low resistance to carbapenems but very high resistance to the third-generation cephalosporins and cefixime. The results showed that some of the Pseudomonas spp. and Aeromonas spp. isolates were extended-spectrum β-lactamase producing bacteria. In conclusion, the strong association between virulence genes and antibiotic resistance in the isolates shows the potential health risk to communities through direct and indirect exposure to the water.

The prevalence, putative virulence genes and antibiotic resistance profiles of Aeromonas spp. isolated from cultured freshwater fishes in peninsular Malaysia

Aeromonas species are ubiquitous in diverse aquatic habitats. High stocking density and improper farm practices can increase the susceptibility of cultured freshwater fishes to motile Aeromonas septicemia (MAS) outbreak. However, polymorphic phenotypes and genotypes can lead to misidentification of Aeromonas isolates from diseased fish. This study characterized a large collection of Aeromonas spp. that were collected from nine important fish farms in Peninsular Malaysia, and to compare these isolates based on their virulence and antibiotic resistance profiles. A total of 124 isolates were obtained from fish with clinical symptoms of MAS that grew on Aeromonas selective agar, were Gram-negative and were oxidase-positive, indicating these as presumptive Aeromonas spp. Based on a phylogenetic analysis of these isolates using gyrB sequences, along with phenotypic analysis based on a series of biochemical tests, five species of Aeromonas were identified among these isolates. Among these isolates, Aeromonas dhakensis was obtained most frequently (43%), followed by A. veronii (22%), A. hydrophila (20%), A. caviae (8%) and A. jandaei (7%). Moreover, 50% of the isolates were found to harbour at least half of the virulence genes tested such as aer, ahp, alt, hly, lip, fla, ela and/or act, while 2% of the isolates were found to harbour none. The Aeromonas isolates displayed resistance to amikacin (5%), ampicillin (100%), cefotaxime (7%), amoxicillin (65%), gentamicin (2%), chloramphenicol (2%) and tetracycline (15%), but not for levofloxacin (0%). The highest multiple antibiotic resistance (MAR) index of 0.63 was found in 1% of the isolates, while the mean MAR index was determined at 0.25. This study reported the prevalence of Aeromonas in cultured freshwater fishes in Peninsular Malaysia, where A. dhakensis was observed as the predominant species. However, the presence of Aeromonas with multiple virulence genes and antibiotic resistance ability should alarm the freshwater fish industry in this country.

Antibiotic Resistance Patterns of Bacteria Isolated from Dechlorinated Water Samples

Chlorination has been the method of choice for disinfecting water used for drinking purposes. However, some stressed bacteria during chlorination are able to recover and alter the potability of water. This study assessed the recovery of stressed bacteria in dechlorinated water. Ten chlorinated water samples were collected from different points within Ilorin metropolis, Kwara, Nigeria. The samples (100ml) were dechlorinated with 0.1ml of 11.4mM sodium thiosulphate solution. The physicochemical characteristics of the chlorinated water samples were determined while bacteriological analyses were carried out on both chlorinated and dechlorinated water samples. The antibiotic susceptibility pattern of the isolates was determined using disc diffusion method. The physicochemical characteristics of the water samples ranged as follow: pH 7.3-8.4, chloride content 4.37-6.85 mg/l, suspended solids 0.004-0.017 g/100ml, and total hardness 30-72mg/l. The chlorinated water samples had bacterial, total, and faecal coliform counts ranging from 1.0 × 101 – 1.9 × 104cfu/ml, 0 – 480 MPN/100ml, and zero, respectively. The dechlorinated water sample had corresponding counts of 5.4 × 102 – 7.36 × 104cfu/ml, 6 - 1100 MPN/100ml, and 0 – 380 MPN/100ml. A total of eleven bacterial species belonging to the genera Bacillus, Burkholderia, Citrobacter, Enterobacter, Enterococcus, Escherichia, Staphylococcus, Serratia, and Streptococcus were isolated. Not lower than 60% of the bacterial isolates were susceptible to ofloxacin and ciprofloxacin. All the isolates exhibited multiple antibiotic resistances. The antibiotic resistance pattern of an isolate of Citrobacter freundii to cefuroxime, cefixime, and gentamycin changed remarkably and was plasmid-mediated, while that of E. coli and Enterobacter agglomerans remained unchanged to all the antibiotics and was non-plasmid mediated. Chlorination of water at the point of use is recommended. It is concluded that chlorination is essential in order to prevent reactivation of stressed bacteria during distribution and prevent infection by bacteria with high multiple antibiotic resistance index.

Molecular Detection of Antibiotic-Resistant Genes in Pseudomonas aeruginosa from Nonclinical Environment: Public Health Implications in Mthatha, Eastern Cape Province, South Africa.

Evaluation of resistant profiles and detection of antimicrobial-resistant genes of bacterial pathogens in the nonclinical milieu is imperative to assess the probable risk of dissemination of resistant genes in the environment. This paper sought to identify antibiotic-resistant genes in Pseudomonas aeruginosa from nonclinical sources in Mthatha, Eastern Cape, and evaluate its public health implications. Samples collected from abattoir wastewater and aquatic environment were processed by membrane filtration and cultured on CHROMagarTM Pseudomonas medium. Species identification was performed by autoSCAN-4 (Dade Behring Inc., IL). Molecular characterization of the isolates was confirmed using real-time polymerase chain reaction (rPCR) and selected isolates were further screened for the possibility of harboring antimicrobial resistance genes. Fifty-one Pseudomonas species were recovered from abattoir wastewater and surface water samples, out of which thirty-six strains were Pseudomonas aeruginosa (70.6%). The P. aeruginosa isolates demonstrated resistance to aztreonam (86.1%), ceftazidime (63.9%), piperacillin (58.3%), cefepime (55.6%), imipenem (50%), piperacillin/tazobactam (47.2%), meropenem (41.7%), and levofloxacin (30.6%). Twenty out of thirty-six P. aeruginosa displayed multidrug resistance profiles and were classified as multidrug-resistant (MDR) (55.6%). Most of the bacterial isolates exhibited a high Multiple Antibiotic Resistance (MAR) Index ranging from 0.08 to 0.69 with a mean MAR index of 0.38. In the rPCR analysis of fifteen P. aeruginosa isolates, 14 isolates (93.3%) were detected harboring blaSHV, six isolates (40%) harbored blaTEM, and three isolates (20%) harbored blaCTX-M, being the least occurring ESBL. Results of the current study revealed that P. aeruginosa isolates recovered from nonclinical milieu are resistant to frontline clinically relevant antipseudomonal drugs. This is concerning as it poses a risk to the environment and constitutes a public health threat. Given the public health relevance, the paper recommends monitoring of multidrug-resistant pathogens in effluent environments.