Bacteria and antibiotic resistance detection in fractures of wild birds from wildlife rehabilitation centres in Spain

Highlights

• Fractures in birds are colonized by a large number of bacteria.

• Osteomyelitis treatment in birds consists of several antibiotics.

• Antibiotic resistance is an emerging health problem.

• Wild birds contribute to the transmission of antibiotic resistant bacteria.

Abstract

Anatomic adaptations make birds more prone to open fractures with exposed bone parts losing vascularization. As a result of this exposure, fractures are colonized by different microorganisms, including different types of bacteria, both aerobic and anaerobic, causing osteomyelitis in many cases. For this reason, antibiotic treatment is common. However, carrying out antibiotic treatment without carrying out a previous antibiogram may contribute to increased resistance against antibiotics, especially in migratory wild birds. In this paper, bacterial counts regarding fracture type, bacterial identification and antibiotic resistance have been analysed in wild birds from wildlife rehabilitation centres in Spain. The results obtained showed that open fractures had higher bacterial counts (CFU/mL) than closed ones. Bacteria in family Enterobacteriaceae, identified were Escherichia spp., Enterobacter spp., Shigella spp., Hafnia alvei, Proteus mirabilis, Leclercia adecarboxylata and Pantoea agglomerans. Other bacteria present in wild birds’ fractures were Aeromonas spp., Enterococcus spp. Bacillus wiedmannii and Staphylococcus sciuri. All species found presented resistance to at least one of the antibiotics used. Wild birds can be implicated in the introduction, maintenance and global spreading of antibiotic resistant bacteria and represent an emerging public health concern. Results obtained in this paper support the idea that it is necessary to take this fact into account before antibiotic administration to wild animals, since it could increase the number of bacteria resistant to antibiotics.

Introduction

Adaptations of birds for flying, such as reduction of weigh and bone modifications, predispose these animals to suffer from fractures in case of traumatic injuries, as collisions with electric lines, shots, car crashes, among others [[1], [2], [3], [4], [5]]. The anatomical adaptation makes birds more prone to open fractures with exposed bone parts losing vascularization. In fact, lack of irrigation through the periosteum, medullary, metatarsal and epiphyseal blood vessels, which are responsible for nourishing the bone and the exposure of the fracture to external contaminants, favor the appearance of osteomyelitis and infections of adjacent tissues, as well as necrosis [6,7]. Osteomyelitis is the infection of bone by pathogens such as fungi or bacteria, both aerobic and anaerobic, as a result of trauma or previous infection [6,8].

Osteomyelitis in birds does not affect systemically, unlike what occurs in mammals. However, if osteomyelitis is found in pneumatic bones, such as the humerus or femur, the infection is in direct contact with the air sacs inside the medullary canal and, therefore, with the whole respiratory system [9]. As osteomyelitis could have multiple possible etiologies, treatment with antimicrobial drugs is diverse. Different authors recommend treatments based on clindamycin, while others use ceftiofur, cefotaxime or enrofoxacin [6,[10], [11], [12]]. Nonetheless, the massive use of antibiotics is not recommended. According to World Health Organization, “antibiotic resistance is one the biggest threats to global health, food security, and development”. In fact, this International Organization reaffirmed its global action plan on antimicrobial resistance, one of its five strategic objectives being to optimize the use of microbial agents in 2019 [13].

Most studies reported antibiotic-resistant bacteria in many parts of the world, even remote areas [14]. This antibiotic-resistant bacteria have been found in different types of wild animals, both mammals and birds [[15], [16], [17], [18], [19], [20]]. In that sense, some authors indicate that wild birds could be an important reservoir of resistance to antibiotics, particularly wild migratory birds for their ability for long range movements [[21], [22], [23], [24], [25]].

The aim of this work is to compare the bacteriological contamination in open and closed fractures in birds from wildlife rehabilitation centres in Spain. Bacterial species and antimicrobial resistance were also evaluated.