Does Nitrofurantoin Improve the Portfolio of Vets against Resistant Bacteria in Companion Animals?

ESBL- and pAmpC-producing Enterobacterales from Swedish dogs and cats 2017-2021: a retrospective study

BACKGROUND

Antibiotic resistant bacteria are a threat to both human and animal health. Of special concern are resistance mechanisms that are transmissible between bacteria, such as extended-spectrum beta-lactamases (ESBL) and plasmid-mediated AmpC (pAmpC). ESBL/AmpC resistance is also of importance as it confers resistance to beta-lactam antibiotics including third generation cephalosporins. The Swedish Veterinary Agency (former English name National Veterinary Institute) performs confirmatory testing of suspected ESBL-/pAmpC-producing Enterobacterales. The aim of this study is to describe the clinical background, antibiotic susceptibility, and genetic relationships of confirmed isolates from dogs and cats in Sweden from 2017 to 2021.

RESULTS

The study includes 92 isolates of ESBL/pAmpC-producing bacteria from 82 dogs, and 28 isolates from 23 cats. Escherichia coli was the most commonly isolated bacteria, and the most frequent sampling site was the urinary tract. From eight dogs and two cats, ESBL/pAmpC-producing bacteria were isolated on more than one occasion. Multi-resistance was more than twice as common in samples from dogs (50%) than in samples from cats (22%). Among dogs, sequence type (ST) 131 and ST372 were the dominant strains and blaCMY-2 and blaCTX-M-15 the dominant genes conferring reduced susceptibility to third-generation cephalosporins. Among cats, ST73 was the dominant strain and blaCTX-M-15 the dominant gene.

CONCLUSIONS

Monitoring the resistance patterns and genetic relationships of bacteria over time is important to follow the results of measures taken to reduce resistance. Knowledge of the appropriate antibiotic usage is also crucial. In this study, a variety of STs and ESBL/pAmpC-genes were detected among the isolates. There were available antibiotics likely effective for treatment in all cases, based on resistance pattern, infection site and host species.

Multidrug-Resistant Commensal and Infection-Causing Staphylococcus spp. Isolated from Companion Animals in the Valencia Region

The emergence of antimicrobial resistance (AMR) and multidrug resistance (MDR) among microorganisms to commonly used antibiotics is a growing concern in both human and veterinary medicine. Companion animals play a significant role in the epidemiology of AMR, as their population is continuously increasing, posing a risk of disseminating AMR, particularly to strains of public health importance, such as methicillin-resistant Staphylococcus strains. Thus, this study aimed to investigate the prevalence of AMR and MDR in commensal and infection-causing Staphylococcus spp. in dogs and cats in Valencia region. For this purpose, 271 samples were taken from veterinary centers to assess antimicrobial susceptibility against 20 antibiotics, including some of the most important antibiotics for the treatment of Staphylococcus infections, including the five last resort antibiotics in this list. Of all the samples, 187 Staphylococcus spp. strains were recovered from asymptomatic and skin-diseased dogs and cats, of which S. pseudintermedius (≈60%) was more prevalent in dogs, while S. felis (≈50%) was more prevalent in cats. In the overall analysis of the isolates, AMR was observed for all antibiotics tested, including those crucial in human medicine. Furthermore, over 70% and 30% of the strains in dogs and cats, respectively, exhibited MDR. This study highlights the significance of monitoring the trends in AMR and MDR among companion animals. The potential contribution of these animals to the dissemination of AMR and its resistance genes to humans, other animals, and their shared environment underscores the necessity for adopting a One Health approach.

In Vitro and In Vivo Trypanocidal Efficacy of Nitrofuryl- and Nitrothienylazines

African trypanosomiasis is a vector-borne disease of animals and humans in the tsetse fly belt of Africa. Trypanosoma congolense ("nagana") is the most pathogenic trypanosome in livestock and causes high morbidity and mortality rates among cattle. In the absence of effective preventative vaccines, the management of trypanosomiasis relies on chemoprophylaxis and/or -therapy. However, the trypanocides in clinical use exhibit poor oral bioavailability and toxicity, and therapeutic failures occur because of resistant strains. Because nitrofurantoin displayed, in addition to its clinical use, promising antiparasitic activity, the current study was conducted to evaluate the in vitro trypanocidal activity and preliminary in vivo treatment efficacy of previously synthesized nitrofuranylazines. The trypanocidal activity of these nitrofuran derivatives varied among the evaluated trypanosome species; however, T. congolense strain IL3000 was more susceptible than other animal and human trypanosomes. The nitrofurylazines 4a (IC50 0.04 μM; SI > 7761) and 7a (IC50 0.03 μM; SI > 9542) as well as the nitrothienylazine 8b (IC50 0.04 μM; SI 232), with nanomolar IC50 values, were revealed as early antitrypanosomal leads. Although these derivatives showed strong trypanocidal activity in vitro, no in vivo treatment efficacy was observed in T. congolense IL3000 infected mice after both oral and intraperitoneal administration in a preliminary study. This was attributed to the poor solubility of the test compounds in the in vivo testing media. Indeed, a challenge in drug discovery is finding a balance between the physicochemical properties of a drug candidate, particularly lipophilicity and water solubility, and maintaining adequate potency to provide an effective dose. Hence, future chemical modifications may be required to generate lead-like to lead-like nitrofuranylazines that possess optimal physicochemical and pharmacokinetic properties while retaining in vitro and, ultimately, in vivo trypanocidal efficacy.