Mycoplasma synoviae (MS) is a highly prevalent bacterial species in poultry causing disease and severe economic losses. Antibiotic treatment is one of the control strategies that can be applied to contain clinical outbreaks in MS-free flocks, especially because this bacterium can be transmitted in ovo. It becomes, then, very important for veterinarians to know the antibiotic susceptibility of the circulating strains in order to choose the most appropriate first-line antibiotic molecule as a proactive role in fighting antibiotic resistance. We evaluated the Minimum Inhibitory Concentrations (MICs) of enrofloxacin, oxytetracycline, doxycycline, erythromycin, tylosin, tilmicosin, spiramycin, tiamulin, florfenicol and lincomycin for MS isolates collected between 2012 and 2017 in Italy. A total of 154 MS isolates from different poultry commercial categories (broiler, layer, and turkey sectors) was tested using commercial MIC plates. All MS isolates showed very high MIC values of erythromycin (MIC90 ≥8 μg/mL) and enrofloxacin (MIC90 ≥16 μg/mL). MIC values of doxycycline and oxytetracycline obtained were superimposable to each other with only a one-fold dilution difference. Discrepancies between MIC values of tylosin and tilmicosin were observed. Interestingly, seven isolates showed very high MIC values of lincomycin and tilmicosin, but not all of them showed very high MIC values of tylosin. Most of the MS isolates showed low MIC values of spiramycin, but seven strains showed a MIC ≥16 μg/mL. In the observation period, the frequency of the different MIC classes varied dependently on the tested antibiotic. Interestingly, tilmicosin MICs clearly showed a time-dependent progressive shift towards high-concentration classes, indicative of an on-going selection process among MS isolates. Until standardized breakpoints become available to facilitate data interpretation, it will be fundamental to continue studying MIC value fluctuations in the meantime in order to create a significant database that would facilitate veterinarians in selecting the proper drug for treating this impactful Mycoplasma.

This study aims to investigate the bacteria involved in equine omphalitis and their susceptibility to antimicrobial drugs, and consequently to provide guidelines concerning the most suitable treatment protocol in accordance with the clinical, ultrasound and laboratory findings. Forty foals aged between one and 30 days were evaluated in the course of this investigation. An ultrasound examination of all umbilical remnants was carried out carefully in all foals; umbilical swabs were collected for bacteriological examination, and blood samples were collected for blood culture from 19 foals with fever and abnormal blood values. Bacterial omphalitis was observed in 95 per cent of foals and bacterial septicaemia was diagnosed in 11 cases. Enterobacteria and coccoid Gram‐positive bacteria were isolated more frequently than Serratia marcescens, Pantoea agglomerans and Trueperella pyogenes . Omphalectomy was performed in 77.5 per cent of the foals examined; the remainder were treated only medically with antimicrobial drugs as recommended by antibiotic susceptibility testing performed for all bacteria isolated. Antibiotic therapy was successful in all foals that only received medical treatment; nevertheless, omphalectomy was performed in most cases particularly in situations of clinical decline despite antibiotic therapy and when involvement of umbilical vein, fever and joint disorders were observed.

From October 2021 to January 2022, different incursions of clade 2.3.4.4b H5N1 HPAIV (Highly Pathogenic Avian Influenza Virus) occurred in several Italian regions with its main diffusion in Densely Poultry Populated Areas (DPPAs) of north-eastern Italy. Monitoring and control activities applied in the affected area clearly evidenced that turkeys and broilers were the most affected species, although several flocks of broilers at times resulted HPAIV H5N1 infected in absence of increased mortality and/or clinical signs. Thus, an approach based on sampling dead birds was adopted in the broiler sector to improve the early detection of infection; this protocol allowed us to confirm that 15 farms were HPAIV-infected with birds ready to be delivered to the slaughterhouse. The aim of this report is to describe the results of the diagnostic activities carried out in one HPAIV H5N1-infected broiler farm, three days after laboratory confirmation during the pre-movement testing without showing increased mortality or clinical signs. Thus, clinical signs, daily cumulative mortality rate (CMR), virus shedding, seroconversion, pathobiology of clade 2.3.4.4b H5N1 HPAIV as well as Avian Influenza Viruses (AIVs) environmental contamination were thoroughly examined in the infected holding. Such in-depth investigation demonstrated low infection prevalence in live birds, low environmental contamination, no seroconversion for AIVs, gross and microscopic findings compatible with systemic infection with peracute death in H5N1 HPAIV-infected birds.

Mycoplasma gallisepticum (Mg) is a highly contagious avian pathogen responsible for significant economic losses for the poultry industry. In some circumstances, antimicrobial treatment is useful to contain clinical signs of Mg infection in birds. However, antimicrobial resistance emergence is now common among animal pathogens, becoming a worldwide health concern. The collection of minimum inhibitory concentration (MIC) data is fundamental for an appropriate antimicrobial use and for fighting antimicrobial resistance emergence. However, MIC data can only be generated in specialized laboratories, and therefore they are not regularly available. MICs of 67 non-vaccine-derived Mg isolates collected in Italy between 2010 and 2020 were obtained. Although 79.1% of the Mg isolates showed enrofloxacin MICs ≥ 8 µg/mL, a statistically significant trend toward low MICs of erythromycin, tylosin, tilmicosin, spiramycin, tiamulin, and lincomycin was observed, indicating a comeback to susceptibility of Mg toward these drugs. Doxycycline proved to be slightly more effective than oxytetracycline. The present study shows that Mg changed its susceptibility toward many of the drugs most commonly used for its containment over a ten-year period.

Mycoplasmas are known as the minimalist microorganisms in the microbes’ world. Their minimalist nature makes them highly sensitive to the environmental conditions and limits their ability to survive for extended periods outside their animal host. Nevertheless, there are documented instances of mycoplasma transmission over significant distances and this phenomenon may be linked to relatively unexplored abilities of mycoplasmas, such as their capacity to synthesize biofilm—the predominant mode of bacterial growth in nature. The authors decided to establish a method aimed at inducing the clustering of mycoplasma planktonic cells within a biofilm in vitro and subsequently assess the capacity of certain avian mycoplasmas to synthesize a biofilm. A total of 299 avian mycoplasma isolates were included in the study, encompassing both pathogenic (Mycoplasma gallisepticum, M. synoviae, M. meleagridis, M. iowae) and non-pathogenic species (M. gallinaceum, M. gallinarum, M. iners and M. pullorum). The authors successfully demonstrated the feasibility of inducing avian mycoplasmas to synthetize in vitro a biofilm, which can be visually quantified. The only species that did not produce any biofilm was M. iowae. In general, the pathogenic mycoplasmas produced greater quantities of biofilm compared to the non-pathogenic ones. Furthermore, it was observed that the ability to produce biofilm appeared to vary, both qualitatively and quantitatively, not only among different species but also among isolates of a single species. Future studies will be necessary to determine whether biofilm production plays a pivotal epidemiological role for the pathogenic avian mycoplasmas.