Salmonella spp. in Pet Reptiles in Portugal: Prevalence and Chlorhexidine Gluconate Antimicrobial Efficacy

Serovar and sequence type distribution and phenotypic and genotypic antimicrobial resistance of Salmonella originating from pet animals in Chongqing, China

A total of 334 Salmonella isolates were recovered from 6,223 pet rectal samples collected at 50 pet clinics, 42 pet shops, 7 residential areas, and 4 plazas. Forty serovars were identified that included all strains except for one isolate that did not cluster via self-agglutination, with Salmonella Typhimurium monophasic variant, Salmonella Kentucky, Salmonella Enteritidis, Salmonella Pomona, and Salmonella Give being the predominant serovars. Fifty-one sequence types were identified among the isolates, and ST198, ST11, ST19, ST451, ST34, and ST155 were the most common. The top four dominant antimicrobials to which isolates were resistant were sulfisoxazole, ampicillin, doxycycline, and tetracycline, and 217 isolates exhibited multidrug resistance. The prevalence of β-lactamase genes in Salmonella isolates was 59.6%, and among these isolates, 185 harbored blaTEM, followed by blaCTX-M (66) and blaOXA (10). Moreover, six PMQR genes, namely, including qnrA (4.8%), qnrB (4.2%), qnrD (0.9%), qnrS (18.9%), aac(6')-Ib-cr (16.5%), and oqxB (1.5%), were detected. QRDR mutations (76.6%) were very common in Salmonella isolates, with the most frequent mutation in parC (T57S) (47.3%). Furthermore, we detected six tetracycline resistance genes in 176 isolates, namely, tet(A) (39.5%), tet(B) (8.1%), tet(M) (7.7%), tet(D) (5.4%), tet(J) (3.3%), and tet(C) (1.8%), and three sulfonamide resistance genes in 303 isolates, namely, sul1 (84.4%), sul2 (31.1%), and sul3 (4.2%). Finally, we found 86 isolates simultaneously harboring four types of resistance genes that cotransferred 2-7 resistance genes to recipient bacteria. The frequent occurrence of antimicrobial resistance, particularly in dogs and cats, suggests that antibiotic misuse may be driving multidrug-resistant Salmonella among pets.IMPORTANCEPet-associated human salmonellosis has been reported for many years, and antimicrobial resistance in pet-associated Salmonella has become a serious public health problem and has attracted increasing attention. There are no reports of Salmonella from pets and their antimicrobial resistance in Chongqing, China. In this study, we investigated the prevalence, serovar diversity, sequence types, and antimicrobial resistance of Salmonella strains isolated from pet fecal samples in Chongqing. In addition, β-lactamase, QRDR, PMQR, tetracycline and sulfonamide resistance genes, and mutations in QRDRs in Salmonella isolates were examined. Our findings demonstrated the diversity of serovars and sequence types of Salmonella isolates. The isolates were widely resistant to antimicrobials, notably with a high proportion of multidrug-resistant strains, which highlights the potential direct or indirect transmission of multidrug-resistant Salmonella from pets to humans. Furthermore, resistance genes were widely prevalent in the isolates, and most of the resistance genes were spread horizontally between strains.

Pathogenic Potential of Opportunistic Gram-Negative Bacteria Isolated from the Cloacal Microbiota of Free-Living Reptile Hosts Originating from Bulgaria

Reptiles are known to be asymptomatic carriers of various zoonotic pathogens. A number of Gram-negative opportunistic commensals are causative agents of bacterial infections in immunocompromised or stressed hosts and are disseminated by reptiles, whose epidemiological role should not be neglected. Since most studies have focused on exotic species, in captivity or as pet animals, the role of wild populations as a potential source of pathogens still remains understudied. In the present study, we isolated a variety of Gram-negative bacteria from the cloacal microbiota of free-living lizard and tortoise hosts (Reptilia: Sauria and Testudines) from the Bulgarian herpetofauna. We evaluated their pathogenic potential according to their antibiotic susceptibility patterns, biofilm-forming capacity, and extracellular production of some enzymes considered to play roles as virulence factors. To our knowledge, the phenotypic manifestation of virulence factors/enzymatic activity and biofilm formation in wild reptile microbiota has not yet been widely investigated. All isolates were found to be capable of forming biofilms to some extent and 29.6% of them could be categorized as strong producers. Two strains proved to be excellent producers. The majority of the isolated strains showed extracellular production of at least one exoenzyme. The most pronounced pathogenicity could be attributed to the newly isolated Pseudomonas aeruginosa strain due to its multiresistance, excellent biofilm formation, and expression of exoenzymes.

Salmonella in reptiles: a review of occurrence, interactions, shedding and risk factors for human infections

Salmonella are considered a part of the normal reptile gut microbiota, but have also been associated with disease in reptiles. Reptile-associated salmonellosis (RAS) can pose a serious health threat to humans, especially children, and an estimated 6% of human sporadic salmonellosis cases have been attributed to direct or indirect contact with reptiles, although the exact number is not known. Two literature searches were conducted for this review. The first evaluated reports of the prevalence of Salmonella in the intestinal tracts of healthy reptiles. Salmonella were most commonly detected in snakes (56.0% overall), followed by lizards (36.9%) and tortoises (34.2%), with lower detection rates reported for turtles (18.6%) and crocodilians (9%). Reptiles in captivity were significantly more likely to shed Salmonella than those sampled in the wild. The majority of Salmonella strains described in reptiles belonged to subspecies I (70.3%), followed by subspecies IIIb (29.7%) and subspecies II (19.6%). The second literature search focused on reports of RAS, revealing that the highest number of cases was associated with contact with turtles (35.3%), followed by lizards (27.1%) and snakes (20.0%). Reptiles associated with RAS therefore did not directly reflect prevalence of Salmonella reported in healthy representatives of a given reptile group. Clinical symptoms associated with RAS predominantly involved the gastrointestinal tract, but also included fever, central nervous symptoms, problems with circulation, respiratory symptoms and others. Disease caused by Salmonella in reptiles appears to be dependent on additional factors, including stress, inadequate husbandry and hygiene, and other infectious agents. While it has been suggested that reptile serovars may cause more severe disease than human-derived strains, and some data is available on invasiveness of individual strains in cell culture, limited information is available on potential mechanisms influencing invasiveness and immune evasion in reptiles and in RAS. Strategies to mitigate the spread of Salmonella through reptiles and to reduce RAS focus mostly on education and hygiene, and have often been met with some success, but additional efforts are needed. Many aspects regarding Salmonella in reptiles remain poorly understood, including the mechanisms by which Salmonella persist in reptile hosts without causing disease.

Study of Zoonotic Pathogens in Alien Population of Veiled Chameleons (Chamaeleo calyptratus) in the Canary Islands (Spain)

Veiled chameleons (Chamaeleo calyptratus) are native to the Arabian Peninsula that have been introduced as pets in many regions around the world, such as the Canary Islands (Spain). In this work, the gastrointestinal content from veiled chameleons of Gran Canaria island (Canary Islands) has been analyzed to determine the presence of zoonotic bacteria. Forty animals were analyzed using different selective culture media and PCR. The most isolated bacteria were Yersinia enterocolitica (52.4%), followed by Salmonella spp. (40.0%), with positive isolates for Salmonella Tyhpi and Salmonella Typhimurium. Pseudomonas spp. was found in 32.5% of the chameleons. More than half were positive for Pseudomonas aeruginosa. Antibiotic-resistant Staphylococcus spp. was detected in six animals plus one isolate of non-resistant Staphylococcus hominis. Multiple mycobacteria species belonging to both tuberculous and non-tuberculous complexes were identified as well as Escherichia coli carrying the stx₁ and eae virulence genes with 12.5% and 7.5% prevalence, respectively. Listeria monocytogenes, Campylobacter spp., and Vibrio spp. were found in lower proportion (<5%). The results obtained indicate that veiled chameleons in Gran Canaria could be playing a role in the maintenance and dissemination of the pathogens detected, harming public health and biodiversity.

Antimicrobial Resistant Salmonella in Chelonians: Assessing Its Potential Risk in Zoological Institutions in Spain

Salmonella is mostly noted as a food-borne pathogen, but contact with chelonians has also been reported as a source of infection. Moreover, high levels of antimicrobial resistance (AMR) have been reported in Salmonella isolated from wild and captive reptiles. The aim of this study was to assess the occurrence of Salmonella AMR carriage by chelonians admitted to two zoological institutions in Spain, characterizing the isolates to assess the Salmonella AMR epidemiology in wildlife. To this end, 152 chelonians from nine species were sampled upon their arrival at the zoological nuclei. Salmonella identification was based on ISO 6579-1:2017 (Annex D), isolates were serotyped and their AMR analysed according to the EU Decision 2013/652. Moreover, the genetic relationship of the isolates was assessed by pulsed-field gel electrophoresis (PFGE). Results showed 19% (29/152) of the chelonians positive to Salmonella, all of them tortoises. For all isolates, 69% (20/29) were resistant and 34% (10/29) multidrug-resistant (MDR) strains. PFGE clustered isolates according to the serovar, confirming a low genetic diversity. In conclusion, this study shows a high presence of MDR Salmonella strains in tortoises at their entry into zoological nuclei. This condition highlights the need to establish Salmonella detection protocols for the entry of animals into these centres.

Identification of Pseudomonas aeruginosa From the Skin Ulcer Disease of Crocodile Lizards (Shinisaurus crocodilurus) and Probiotics as the Control Measure

The crocodile lizard (Shinisaurus crocodilurus) is an endangered ancient reptile species. Captive breeding is an important conservation measure for the potential restoration and recovery of their wild populations. However, a skin ulcer disease caused by an unknown pathogen has become a serious threat to captive breeding individuals. In the current study, based on microbial isolation, we identified Pseudomonas aeruginosa as the dominant pathogen in skin ulcer disease. Chinese skinks (Plestiodon chinensis) were used to verify the pathogenicity of P. aeruginosa in skin ulcer disease in vivo. As expected, subcutaneous inoculation of P. aeruginosa induced skin disease in healthy skinks and P. aeruginosa was re-isolated from the induced skin ulcers. Therefore, P. aeruginosa, an opportunistic and ubiquitous pathogen that causes a wide range of infections, appears to be the main pathogen of the skin disease affecting crocodile lizards. In the aquaculture industry, probiotics are widely used in the prevention and control of animal diseases caused by such pathogens. Here, we administered probiotics to the breeding crocodile lizards for 6 months. The three experiment groups treated with different kinds of probiotics showed significance at controlling case incidence. Three of the four groups treated with probiotics showed significant disease prevention (Effective Microorganisms mixed probiotics P = 0.0374; Double-dose Effective Microorganisms, P = 0.0299; Bacillus subtilis, P = 0.0140, T-test), and CFUs in the water of the breeding enclosures were also inhibited after probiotics usage (P < 0.001, T-test). Our study demonstrated the role of Pseudomonas aeruginosa in development of skin ulcer disease of crocodile lizards in a local zoo and offered the probiotic-based method for control measurements, which would be of benefit for the conservation of endangered reptiles.

Zoonotic potential and prevalence of Salmonella serovars isolated from pets

Salmonellosis is a global health problem, affecting approximately 1.3 billion people annually. Most of these cases are related to food contamination. However, although the majority of Salmonella serovars are pathogenic to humans, animals can be asymptomatic carriers of these bacteria. Nowadays, a wide range of animals is present in human households as pets, including reptiles, amphibians, dogs, cats, ornamental birds, and rodents. Pets contaminate the environment of their owners by shedding the bacteria intermittently in their feaces. In consequence, theyare thought to cause salmonellosis through pet-to-human transmission. Each Salmonella serovar has a different zoonotic potential, which is strongly regulated by stress factors such as transportation, crowding, food deprivation, or temperature. In this review, we summarize the latest reports concerning Salmonella-prevalence and distribution in pets as well as the risk factors and means of prevention of human salmonellosis caused by contact with their pets. Our literature analysis (based on PubMed and Google Scholar databases) is limited to the distribution of Salmonella serovars found in commonly owned pet species. We collected the recent results of studies concerning testing for Salmonella spp. in biological samples, indicating their prevalence in pets, with regard to clinical cases of human salmonellosis.