antimicrobial susceptibility tests
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2022 ◽  
Vol 43 (2) ◽  
pp. 641-656
Aura Lacerda Crepaldi ◽  
Aline Simões da Rocha Bispo ◽  
Dennifier Costa Brandão Cruz ◽  
Washington Luiz Gomes Tavechio ◽  

The indiscriminate use of synthetic veterinary drugs in fish farms for disease control has caused recurring environmental pollution and reduced productivity; however, the search for ecologically viable alternatives is increasing. Thus, this study aimed to evaluate the phytochemical characterization of the hexanic, methanolic, and aqueous extracts of black jurema (M. tenuiflora), and their antimicrobial activity against strains of Aeromonas, and acute toxicity (LC50) to fingerlings of O. niloticus. The isolates were identified, and phenotypic virulence and antimicrobial susceptibility tests were performed. A. caviae, and A. veronii bv. veronii showed 75.0 - 87.5% positivity for the virulence factors tested, and resistance to the antimicrobials ampicillin, amoxicillin, erythromycin, and tetracycline of 67.0% and 50.0%, respectively. Phytochemical screening of black jurema extracts detected phenols, flavonoids, tannins, saponins, alkaloids, and steroids/triterpenoids, with methanol proving to be more efficient in the extraction of metabolites. The methanolic and aqueous extracts showed moderate antimicrobial activity, with minimum inhibitory concentration and minimum bactericidal concentration of 250 μg mL-1, and the methanolic extract revealed an LC50 of 40 μg mL-1 for O. niloticus. This study demonstrated the efficiency of the in vitro antimicrobial activity of M. tenuiflora extracts, and their use in vivo in the treatment or prophylaxis in fish farming can be investigated to replace the use of synthetic antimicrobials.

Antibiotics ◽  
2022 ◽  
Vol 11 (1) ◽  
pp. 102
Daniela Fortini ◽  
Slawomir Owczarek ◽  
Anna Dionisi ◽  
Claudia Lucarelli ◽  
Sergio Arena ◽  

Background: A collection of human-epidemiologically unrelated S. enterica strains collected over a 3-year period (2016 to 2018) in Italy by the national surveillance Enter-Net Italia was analysed. Methods: Antimicrobial susceptibility tests, including the determination of minimal inhibitory concentrations (MICs) for colistin, were performed. Colistin resistant strains were analysed by PCR to detect mobile colistin resistance (mcr) genes. In mcr-negative S. enterica serovar Enteritidis strains, chromosomal mutations potentially involved in colistin resistance were identified by a genomic approach. Results: The prevalence of colistin-resistant S. enterica strains was 7.7%, the majority (87.5%) were S. Enteritidis. mcr genes were identified only in one strain, a S. Typhimurium monophasic variant, positive for both mcr-1.1 and mcr-5.1 genes in an IncHI2 ST4 plasmid. Several chromosomal mutations were identified in the colistin-resistant mcr-negative S. Enteritidis strains in proteins involved in lipopolysaccharide and outer membrane synthesis and modification (RfbN, LolB, ZraR) and in a component of a multidrug efflux pump (MdsC). These mutated proteins were defined as possible candidates for colistin resistance in mcr-negative S. Enteritidis of our collection. Conclusions: The colistin national surveillance in Salmonella spp. in humans, implemented with genomic-based surveillance, permitted to monitor colistin resistance, determining the prevalence of mcr determinants and the study of new candidate mechanisms for colistin resistance.

2021 ◽  
Vol 36 (4) ◽  
pp. 253-262
Mohammed T. Mostafa ◽  
Khalid S. Mustafa ◽  
Brijesh Kumar

Urinary tract infections are very common among people of all ages, but the disease is more prevalent in women, so proper clinical and laboratory diagnosis, and the right treatment are very important to avoid complications and antimicrobial resistance. This study aimed to determine the bacterial causes and antibiotic susceptibility patterns of UTI patients. Recorded results of 6065 urine sample cultures and their antimicrobial susceptibility tests from the Department of Microbiology in Tobruk Medical Center, Tobruk City, were obtained from September 2016 to December 2018. The data was analyzed and discussed in compare with other studies. The study showed that a UTI is more common in females (78.8%) compared with male patients (21.2%). Gram-negative bacteria accounted for the majority of urinary pathogens (90%), where E. coli alone was (58.4%), klebsiellae (17.4%), Proteus (10.7%), while Pseudomonas species was the least common (3.3%) of the total. While the Gram-positive bacteria S. aureus constituted 9.6% of the total. The study was found statistically significant (P=0.000). The most effective antibiotics against all uropathogens were Imipenem and Amikacin, and less effective antibiotics were Ampicillin and Amoxicillin-clavulanic acid. This study concluded that the most common cause of UTI in Tobruk was Escherichia coli and the most effective antibiotics appear to be Imipenem and Amikacin.

2021 ◽  
Vol 11 (1) ◽  
pp. 20-23
Jannatul Mawa ◽  
Saurab Kishore Munshi ◽  
Amatun Nur Mou ◽  
Ifra Tun Nur

Globally, the ornamental fish business has a high demand for its popularity as well as for its profitability. However, microbial contamination, nutrient depletion and accumulation of organic materials are the major factors in an aquafarming system which can cause death of aquatic animal and causes financial losses. This study aimed to determine the physicochemical and microbiological quality of fish aquarium water. Water of different time interval after treatment (7 days, 20 days, 30 days, 60 days, 90 days) were taken from the different aquariums. A set of physicochemical parameters such as temperature, transparency, pH, conductivity, dissolved oxygen, total dissolved solids, alkalinity, total hardness, conductivity were found within the approved standard concentration for fish. The present study also reveals the microbiological status of the aquaculture water where the total viable count ranging from 2.20×104 to 4.20×104 cfu/ml. Escherichia coli, Staphylococcus spp., and Pseudomonas spp. were present in all samples. Antimicrobial susceptibility tests were also done to determine the antibiotic resistance pattern of microbes isolated from aquarium water. Stamford Journal of Microbiology, Vol.11 (1) 2021: 20-23

Animals ◽  
2021 ◽  
Vol 11 (11) ◽  
pp. 3232
Daniel Nenene Qekwana ◽  
Agricola Odoi ◽  
James Wabwire Oguttu

Cross-resistance occurs between antimicrobials with either similar mechanisms of action and/or similar chemical structures, or even between unrelated antimicrobials. This study employed a multivariate approach to investigate the associations between the efficacy profile of antimicrobials and the clustering of eleven different antimicrobial agents based on their efficacy profile. Records of the susceptibility of 382 confirmed Staphylococcus species isolates against 15 antimicrobials based on the disc diffusion method were included in this study. Tetrachoric correlation coefficients were computed to assess the correlations of antimicrobial efficacy profiles against Staphylococcus aureus. Principal components analysis and factor analysis were used to assess the clustering of antimicrobial susceptibility profiles. Strong correlations were observed among aminoglycosides, penicillins, fluroquinolones, and lincosamides. Three main factors were extracted, with Factor 1 dominated by the susceptibility profile of enrofloxacin (factor loading (FL) = 0.859), gentamicin (FL = 0.898), tylosin (FL = 0.801), and ampicillin (FL = −0.813). Factor 2, on the other hand, was dominated by the susceptibility profile of clindamycin (FL = 0.927) and lincomycin-spectinomycin (FL = 0.848) and co-trimazole (FL = −0.693). Lastly, Factor 3 was dominated by the susceptibility profile of amoxicillin-clavulanic acid (FL = 0.848) and cephalothin (FL = 0.824). Antimicrobials belonging to the same category or class of antimicrobial, tended to exhibit similar efficacy profiles, therefore, laboratories must choose only one of the antimicrobials in each group to help reduce the cost of antimicrobial susceptibility tests.

2021 ◽  
Vol 6 (3) ◽  
pp. 5-10
Helen Oroboghae Ogefere ◽  
Sylvester Igweh

Multidrug resistant Staphylococcus aureus has increasingly been implicated as an agent of clinical infections worldwide. This study investigated the prevalence of Vancomycin resistant S. aureus (VRSA) among S. aureus causing infections in Benin City, Nigeria. A total of 400 non-repetitive S. aureus isolates were obtained from clinical specimens in the University of Benin Teaching Hospital. These isolates were identified by standard microbiological tests. Antimicrobial susceptibility tests and screening for vancomycin resistance (using phenotypic method) was carried out for all isolates. Eighteen isolates (4.5%) were resistant to vancomycin with 10 (2.5%) VRSA isolates recovered from females while 8(2.0%) were isolated from males (p = 0.9981). Isolates from catheter tip had the highest prevalence of VRSA (33.3%) and showed statistical significance in comparison with other clinical specimens (p = 0.0036). Vancomycin resistant S. aureus isolates showed poor susceptibility to commonly used antibacterial agents (< 50%). In order to mitigate the effect of selective pressure on the survival and proliferation of resistant strains, prudent use of vancomycin and other antimicrobial agents is advocated. The need for continuous surveillance, susceptibility testing and screening cannot be overemphasized.

Neda Yousefi Nojookambari ◽  
Mehrzad Sadredinamin ◽  
Razieh Dehbanipour ◽  
Zohreh Ghalavand ◽  
Gita Eslami ◽  

Abstract Background β-Lactam antibiotics have been broadly used for the treatment of Acinetobacter baumannii infections, resulting in development of β-lactam inactivating β-lactamases. Here, we described antibiotic resistance rate, prevalence of β-lactamase-encoding genes, and clonal relationships of A. baumannii strains isolated from children referred to Children’s Medical Center in Tehran, Iran, during 2019–2020. Methods A total of 60 non-replicate A. baumannii isolates were recovered from clinical specimens of pediatric patients. Antibiotic susceptibility testing was done by the disc diffusion method. Colistin susceptibility of isolates was performed by the broth microdilution method. β-lactamase-encoding genes were characterized by PCR. The presence of ISAba1 element upstream of the several oxacillinase genes was also checked. Genetic relatedness of isolates was determined by using random amplification of polymorphic DNA (RAPD) typing. Results The antimicrobial susceptibility tests showed that 83.3% of A. baumannii isolates were MDR, and 40% XDR. Both MDR and XDR A. baumannii isolates were susceptible to colistin. The frequency of blaOXA-51-like, blaOXA-23-like, blaTEM, blaOXA-24-like, blaPER, blaSHV, blaCTX-M, blaOXA-58-like, and blaIMP was 100, 93.33, 60, 36.67, 28.33, 8.33, 5, 3.33, and 1.67%, respectively. Coexistence of ISAba1/blaOXA-23-like and ISAba1/blaOXA-51-like was observed in 65% and 85% of isolates, respectively. RAPD analysis revealed 4 common types and 2 single types of A. baumannii isolates. Conclusions The multiple clones harboring blaOXA-23-like, ISAba1-blaOXA-51-like, and ISAba1-blaOXA-23-like were responsible for the spread of A. baumannii isolates in our clinical wards. Dissemination of the well-established clones is worrisome and would become therapeutic challenges due to the possible transferring genetic elements associated with resistance.

2021 ◽  
Vol 12 ◽  
Brendha Truccollo ◽  
Paul Whyte ◽  
Catherine M. Burgess ◽  
Declan J. Bolton

Background:Campylobacter is commonly transmitted to humans from chickens. Campylobacter jejuni is the species most frequently associated with human illness, and the most prevalent species recovered from poultry.Objective: The objective of this study was to analyse a sub-population of C. jejuni from two broiler flocks on the farm and at slaughter using whole-genome sequencing to gain insights into the changes in the Campylobacter population during broiler production, including changes in virulence and antimicrobial resistance profiles.Methods: In this study, ten composite faecal samples (n=10), obtained by pooling ten fresh faecal samples (n=10), were collected in the broiler house on two farms on days 14, 21, 28, and 34 (n=80) and ten composite (n=10) caecal samples were collected at the time of slaughter for each flock (n=20). These were tested for C. jejuni using the ISO 10272-2:2016 method. Seven isolates were randomly selected from each of the nine Campylobacter-positive sampling points (n=63) and were subjected to antimicrobial susceptibility tests. Their genomes were sequenced and the data obtained was used to characterise the population structure, virulence, antimicrobial resistance determinants and inter-strain variation.Results: The Farm 1 isolates had three MLST types (ST257-257, ST814-661 and ST48-48) while those on Farm 2 were ST6209-464 and ST9401. Interestingly, only the MLST types positive for most of the virulence genes tested in this study persisted throughout the production cycle, and the detection of antimicrobial resistance determinants (gyrA T86I and tetO) increased after thinning and at slaughter, with the detection of new strains.Conclusion: The persistence of the most virulent strains detected in this study throughout the production cycle has important implications for the risk to consumers and requires further investigation. The detection of new strains within the population corresponding with the time of thinning and transportation reflects previous reports and provides further evidence that these activities pose a risk of introducing new Campylobacter strains to broiler batches.

Diagnostics ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 1514
Ya-Wen Tsai ◽  
Ting-Chia Lin ◽  
Hsiu-Yin Chou ◽  
Huei-Ya Hung ◽  
Che-Kim Tan ◽  

The current processes used in clinical microbiology laboratories take ~24 h for incubation to identify the bacteria after the blood culture has been confirmed as positive and fa further ~24 h to report the results of antimicrobial susceptibility tests (ASTs). Patients with suspected bloodstream infection are treated with empiric broad-spectrum antibiotics but delayed targeted antimicrobial therapy. This study aimed to develop a method with a significantly shortened turnaround time for clinical application by identifying the optimal incubation period of a subculture. A total of 188 positive blood culture samples obtained from Nov. 2019 to Aug. 2020 were included. Compared to the conventional 24-h incubation for bacterial identification, our approach achieved 96.1% and 97.4% identification accuracy after shortening the incubation time to 4.5 and 3.5 h for gram-positive (GP) and gram-negative (GN) bacterial samples, respectively. Samples from short-term incubation without any intermediate step or process were directly subjected to analysis with the Phoenix M50 AST. Compared to the conventional disk diffusion AST, the category agreements for GP (excluding Streptococcus spp.), Streptococcus spp., and GN bacterial samples were 91.8%, 97.5%, and 92.7%, respectively. Our approach significantly reduced the average turnaround time from 48 h to 28 h for reporting bacterial identity and decreased average AST from 72 h to 50.3 h compared to the conventional methods. Accordingly, this approach allows a physician to prescribe the appropriate antibiotic(s) ~21.7 h earlier, thereby improving patient outcomes.

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