Abstract: Pasteurella spp. is a gram-negative bacterium that is part of the oral and upper respira-tory tract microbiota of many animals such as canids and felines. In humans it can produce pa-thology primarily associated with animal bites or scratches. In addition, members of this genus, and especially Pasteurella multocida, may also be involved in systemic infections, mainly in im-munocompromised patients in close contact with pets. The aim of this study is to analyse the prevalence and clinical characteristics of infections caused by Pasteurella spp. as well as the sensitivity profile of these isolates obtained in the Microbiology laboratory of the Hospital Can Misses (Ibiza, Ibiza and Formentera Health Area, ASEF) in the period from January 2013 to December 2018. The group of islands of Ibiza and Formentera is known as the Pitiusas Islands. Retrospective descriptive study in which all Pasteurella spp. isolates were analysed in the Microbiology Laboratory of Hospital Can Misses from 1 January 2013 to 31 De-cember 2018. Bacterial identification was performed by Vitek 2 automated biochemical test panel (bioMérieux, Spain) and antimicrobial susceptibility by E-test or antibiotic discs in Mueller-Hinton blood agar, interpreted based on European Committee on An-timicrobial Susceptibility Testing (EUCAST) standards, 2022 version. Medical records were systematically reviewed by collecting demographic data of infected patients, comorbidities, epidemiological data and clinical features of the infection. A total of 22 isolates of Pasterurella spp. were obtained from 22 different patients, 62.8% female, from three different species: 18 P. multocida, 2 P. canis and 2 P. pneumo-tropica. Most isolates came from soft tissue infection samples: 7 wound exudates and 5 abscess material. The antibiotics tested with the highest sensitivity profile were gen-tamicin and cefepime (100% sensitivity). The species most commonly isolated in our environment is P. multocida. Close contact with companion animals, especially cats and dogs, is the main risk factor for Pasteurella spp. infections, although in many cases such contact cannot be established. So Pasteurella spp. infection should be considered a zoonosis in possible emergency, especially in rural areas such as Pitiusas Islands.

Under the pressure of fluoroquinolones, Pasteurella multocida (PM) can easily develop resistance to fluoroquinolones mediated by QRDR target mutation. It is imperative to find new drug resistance inhibitor targets to combat the rapid development of drug resistance. In order to overcome these problems, we sequenced the transcriptome of PM with different levels of resistance to ENR(0.03 μg/mL; 8 μg/mL; 32μg/Ml, Enrofloxacin). The results showed that with the increase of resistance to fluoroquinolones, the expression of satP gene was significantly up-regulated. The satP gene deletion strain and replenishment strain were constructed, and their drug resistance and tolerance were determined. The results showed that the deletion of satP gene did not affect the resistance of PM to fluoroquinolones, rather affected the time when PM developed resistance to fluoroquinolones. After 10 generations of drug induction, the MIC (minimum inhibitory concentration) of fluoroquinolones for wild strain was 64 μg/mL, while the MIC for satP gene deletion strain was only 8 μg/mL. The MDK99 test (time to kill 99% bacteria),agar diffusion test and mutation frequency test showed that the tolerance of satP gene deletion strain was significantly lower than that of wild strain. At the same time, the virulence of gene deletion strain and wild strain was tested, and about 400 times decreased virulence was observed for satP gene deletion strain. The mouse infection model confirmed that mice infected with satP gene deletion strains were more likely to be treated with ENR than mice infected with wild-type bovine PM strains. The results show that satP has potential to be a target of fluoroquinolone resistance inhibitors.

Forty-eight Pasteurella multocida isolates were recovered from porcine pneumonic lungs collected in Norwestern Spain (2017- 2019). These isolates were characterized for their minimal inhibition concentrations to twelve antimicrobial agents and for the appearance of eight resistance genes: tetA, tetB, blaROB1, blaTEM, ermA, ermC, mphE and msrE. Relevant resistance percentages were shown to teracyclines, sulphamethoxazole/trimethoprim and tiamulin, thus suggesting that P. multocida isolates were mostly susceptible to amoxicillin, ceftiofur, enrofloxacin, florfenicol, marbofloxacin and macrolides. 29.2% of isolates were resistant to more than two antimicrobials. The tetracycline resistance genes (tetA and tetB) were detected in 22.9% of the isolates, but none was positive to both simultaneously; blaROB1 and blaTEM genes were found in one third of isolates but both genes were detected simultaneously in only one isolate. ermC gene was observed in 41.7% of isolates, a percentage that decreased until 22.9% for msrE; finally, ermA was harboured by 16.7% and mphE was not found in any of them. Six clusters were established based on hierarchical clustering analysis on antimicrobial susceptibility for the twelve antimicrobials. Generally, it was unable to foresee the antimicrobial susceptibility pattern for each family and the association of each particular isolate inside the clusters established from the presence or absence of the resistance genes analyzed.

The antibiotic residues and pathogenic resistance against the drug are very common in poultry due to usage of antibiotics in their feed. It is the need of the time to use natural feed additives as effective alternatives instead of synthetic antibiotic. The aim of this study was to investigate the immune response of Nigella sativa and Curcuma longa in broilers under biological stress against Pasteurella multocida. The total 100, one-day old chicks were divided into 5 groups. The Groups 1 and 2 were served as control negative and control positive. Both control groups were receiving simple diet without any natural feed additives but infection was given in Group 2 at day 28 with the dose of 5.14×107 CFU by IV. Groups 3A & 3B were offered 2% seed powder of Nigella sativa, Groups 4A & 4B were offered Curcuma longa 1% in powdered form and Group 5A & 5B were offered both Curcuma longa 1% & Nigella sativa 2% in feed from day 1 and groups 3B, 4B and 5B were challenged with Pasteurella multocida. The Haemagglutination inhibition titter against Newcastle Disease Virus (NDV), feed conversion ratio, mortality, gross and histopathology were studied. The results of this study revealed that haemagglutination inhibition titers against NDV were highly significant (P< 0.05) in treated groups, highest titers (3A 6.8, 3B 6.4 and 5A 7.2) were obtained from treated Group. The feed conversion ratio (FCR) of Nigella sativa + Curcuma longa treated Groups (5A 1.57 and 3A 1.76) were higher as compared to other non-treated groups. The gross and histopathological changes were much severe in control positive, but less changes were seen in treated groups. Therefore, we recommend that natural feed additives; black cumin (Nigella sativa) and turmeric (Curcuma longa) act as immune enhancer in broilers against Pasteurella multocida.