Investigating the ecology and microbiology of the urban and rural Hooded Crow (Corvus cornix) in Hungary

Dátum
Folyóirat címe
Folyóirat ISSN
Kötet címe (évfolyam száma)
Kiadó
Absztrakt

Urbanisation is a complex process that creates an interconnected interface that influences humans, wildlife, and the environment. To understand this interface, Hooded Crow's success in cities was studied. First, morphological differences between urban and rural crows were examined. Then, the presence of antimicrobial-resistant bacteria (ARB) in these birds was investigated, focusing primarily on extended-spectrun beta-latamase (ESBL)-producing Enterobacterales and vancomycin-resistant enterococci (VRE). We collected morphometric data from 249 crows from two urban and two rural areas. Urban individuals were smaller than rural ones, displaying shorter tarsi. No other differences were detected. Due to plenty of anthropogenic food sources, urban adult crows seem to be able to maintain a similar body mass as their rural counterparts. Our results also showed that juveniles from urban habitats have longer and larger bills but smaller body sizes, exhibiting shorter tarsi and smaller skulls. However, due to the low sample size of rural juveniles (n =3), these findings are not conclusive. In urban areas, differences between crows seemed to be age-dependent and may be related to the availability of food sources. Young crows from a larger city (Budapest) have longer and thicker bills and better body condition than those from a smaller city (Debrecen). However, lower body conditions in juveniles from Debrecen may also be explained by other factors, such as poor health status. In Debrecen, young individuals captured at the city Zoo were generally bigger in size, with higher body mass, better body condition, more fat reserves, longer bodies, and wider skulls and bills than individuals caught in the other study areas, suggesting that local factors may influence a habitat’s effect on crows’ growth. To assess the prevalence of ARB in Hooded Crows, 264 faecal samples were collected and analysed. Bacteria were cultured, isolated, and identified using MALDI TOF. The susceptibility test was performed following EUCAST recommendations, and ESBL producers were identified per the double-disc synergy method. ESBL genes were identified using PCR, and E. coli isolates were characterised by WGS. Four rural samples and 125 urban ones (7% vs. 60%, chi-square p<0.0001) yielded ESBL-producers with the overwhelming dominance of E. coli (2/4 and 105/125 in rural and urban positive birds, respectively). The blaCTX-M-1 group was the most predominant. None of the samples yielded VRE. Based on the WGS, in addition to the presence of ESBL-encoding genes, particularly blaCTX-M-1/55/15, genes encoding resistance to other antimicrobial classes were also detected, and various virulence genes in association with several plasmids (mainly IncI-1 and IncF plasmid groups), were predicted. Most isolates belonged to B1 and A phylogenetic groups, suggesting that Hooded Crows carry commensal ESBL producers and might serve as reservoirs of ESBL-encoding genes. Overall, 22 sequence types (STs) and 33 distinct core-genome MLSTs were defined. The most prevalent STs were previously described in human and animal isolates including wildlife. Some STs found, such as ST4412 and ST5798, have yet to be reported in humans and/or animals. The high frequency of ESBL producers carried by urban Hooded Crows points out the role of anthropogenic sources in ESBL occurrence. Yet, it seems that Hooded Crows from Hungary are not necessarily reservoirs of VREs. Nonetheless, the prevalence of resistance genes found strengthens the notion that even free-ranging birds, with increasing contact with humans, pose health-related threats. In summary, here we demonstrated the possible link between AMR carriage by the Hooded Crow and its urban adaptation. We believe that understanding what influences the success of wild birds in urban habitats might mitigate the surveillance of AMR emergence in such hosts and potentially help identify appropriate actions.

Leírás
Kulcsszavak
Corvids, wild birds, Bacterias, Antimicrobial resistance, AMR, WGS, Enterobacterales, Extended Spectrum Beta Lactamases, ESBL
Forrás