Phenotypic and genotypic resistance profile of Salmonella Typhimurium to antimicrobials commonly used in poultry

Molecular identification of fluoroquinolone resistance in Salmonella spp. isolated from broiler farms and human samples obtained from two regions in Colombia

Background and Aim:

Salmonella is one of the most common foodborne pathogens, the emergence of antibiotic-resistant strains of which is increasing. The aim of this study was to phenotypically and genotypically characterize the fluoroquinolone resistance of Salmonella isolates from broiler and humans in two regions of Colombia.

Materials and Methods:

Salmonella strains (n=49) were evaluated. The phenotype of antibiotic resistance was assessed by an automated method and agar diffusion method, as well as the presence of the quinolone resistance genes qnrA, qnrB, qnrC, qnrD, qnrS, and aac(6’)-Ib as determined by polymerase chain reaction.

Results:

Strains were resistant to ciprofloxacin (75%), levofloxacin (57.1%), and enrofloxacin (38.8%). Molecular identification showed that 24 out of 49 strains possessed the qnrB gene (48.9%), while only one isolate from the Santander region possessed the aac(6’)-Ib gene. Regarding Class 1 integron, it was present in 11 out of the 49 strains (22.44%).

Conclusion:

This study reports the presence of the gene qnrB as well the presence of Class 1 integrons in broiler Salmonella isolates, which may contribute to the resistance to fluoroquinolones.

Antimicrobial Resistance Profiling of Biofilm Forming Non Typhoidal Salmonella enterica Isolates from Poultry and Its Associated Food Products from Pakistan

Salmonellosis caused by non-typhoidal Salmonella enterica from poultry products is a major public health concern worldwide. This study aimed at estimating the pathogenicity and antimicrobial resistance in S. enterica isolates obtained from poultry birds and their food products from different areas of Pakistan. In total, 95/370 (25.67%) samples from poultry droppings, organs, eggs, and meat were positive for Salmonella. The isolates were further identified through multiplex PCR (mPCR) as Salmonella Typhimurium 14 (14.7%), Salmonella Enteritidis 12 (12.6%), and other Salmonella spp. 69 (72.6%). The phenotypic virulence properties of 95 Salmonella isolates exhibited swimming and/or swarming motility 95 (100%), DNA degrading activity 93 (97.8%), hemolytic activity 92 (96.8%), lipase activity 87 (91.6%), and protease activity 86 (90.5%). The sopE virulence gene known for conferring zoonotic potential was detected in S. Typhimurium (92.8%), S. Enteritidis (100%), and other Salmonella spp. (69.5%). The isolates were further tested against 23 antibiotics (from 10 different antimicrobial groups) and were found resistant against fifteen to twenty-one antibiotics. All isolates showed multiple drug resistance and were found to exhibit a high multiple antibiotic-resistant (MAR) index of 0.62 to 0.91. The strong biofilm formation at 37 °C reflected their potential adherence to intestinal surfaces. There was a significant correlation between antimicrobial resistance and the biofilm formation potential of isolates. The resistance determinant genes found among the isolated strains were bla_TEM-1 (59.3%), bla_OxA-1 (18%), bla_PSE-1 (9.5%), bla_CMY-2 (43%), and ampC (8.3%). The detection of zoonotic potential MDR Salmonella in poultry and its associated food products carrying cephalosporin and quinolone resistance genes presents a major threat to the poultry industry and public health.

Molecular Characterization and Survive Abilities of Salmonella Heidelberg Strains of Poultry Origin in Brazil

The aim of the study was to evaluate the genotypic and phenotypic characteristics of 20 strains of S. Heidelberg (SH) isolated from broilers produced in southern Brazil. The similarity and presence of genetic determinants linked to virulence, antimicrobial resistance, biofilm formation, and in silico-predicted metabolic interactions revealed this serovar as a threat to public health. The presence of the ompC, invA, sodC, avrA, lpfA, and agfA genes was detected in 100% of the strains and the luxS gene in 70% of them. None of the strains carries the bla_SHV, mcr-1, qnrA, qnrB, and qnrS genes. All strains showed a multidrug-resistant profile to at least three non-β-lactam drugs, which include colistin, sulfamethoxazole, and tetracycline. Resistance to penicillin, ceftriaxone (90%), meropenem (25%), and cefoxitin (25%) were associated with the presence of bla_CTX–M and bla_CMY–2 genes. Biofilm formation reached a mature stage at 25 and 37°C, especially with chicken juice (CJ) addition. The sodium hypochlorite 1% was the least efficient in controlling the sessile cells. Genomic analysis of two strains identified more than 100 virulence genes and the presence of resistance to 24 classes of antibiotics correlated to phenotypic tests. Protein-protein interaction (PPI) prediction shows two metabolic pathways correlation with biofilm formation. Virulence, resistance, and biofilm determinants must be constant monitoring in SH, due to the possibility of occurring infections extremely difficult to cure and due risk of the maintenance of the bacterium in production environments.

Antibiotic resistance in Salmonella spp. isolated from poultry: A global overview

Salmonella enterica is the most important foodborne pathogen, and it is often associated with the contamination of poultry products. Annually, Salmonella causes around 93 million cases of gastroenteritis and 155,000 deaths worldwide. Antimicrobial therapy is the first choice of treatment for this bacterial infection; however, antimicrobial resistance has become a problem due to the misuse of antibiotics both in human medicine and animal production. It has been predicted that by 2050, antibiotic-resistant pathogens will cause around 10 million deaths worldwide, and the WHO has suggested the need to usher in the post-antibiotic era. The purpose of this review is to discuss and update the status of Salmonella antibiotic resistance, in particular, its prevalence, serotypes, and antibiotic resistance patterns in response to critical antimicrobials used in human medicine and the poultry industry. Based on our review, the median prevalence values of Salmonella in broiler chickens, raw chicken meat, and in eggs and egg-laying hens were 40.5% ( interquartile range [IQR] 11.5-58.2%), 30% (IQR 20-43.5%), and 40% (IQR 14.2-51.5%), respectively. The most common serotype was Salmonella Enteritidis, followed by Salmonella Typhimurium. The highest antibiotic resistance levels within the poultry production chain were found for nalidixic acid and ampicillin. These findings highlight the need for government entities, poultry researchers, and producers to find ways to reduce the impact of antibiotic use in poultry, focusing especially on active surveillance and finding alternatives to antibiotics.

Highly clonal relationship among Salmonella Enteritidis isolates in a commercial chicken production chain, Brazil

In this study, we described the comparison among pulsed-field gel electrophoresis (PFGE), random amplified polymorphic DNA (RAPD), ribotyping, and PCR-ribotyping methods for subtyping Salmonella Enteritidis isolated from an industrial chicken production chain. One hundred and eight S. Enteritidis were isolated at all stages of poultry meat processing plant. These isolates were pheno- and genotypically characterized by using antimicrobial susceptibility test, phage typing, RAPD, PFGE, ribotyping, and PCR-ribotyping. The highest antibiotic resistance rates were observed for enrofloxacin (18.5%) followed by furazolidone (15.7%), cefoxitin (1.8%), ciprofloxacin, and ampicillin with 0.9% each one, while seven isolates (6.4%) were pan-susceptible. Most strains belonged to the globally disseminated phage type PT4 (n = 74; 69.2%). Additionally, we identified strains belonging to phage types PT1 (n = 19; 17.8%) and PT7a (n = 14; 13.1%). Moreover, our results showed that these four molecular methods indicate similar results showing high similarity (≥ 90%) among S. Enteritidis strains, suggesting that these isolates appear to be from a common ancestor being spread at all stages of the poultry production chain. In summary, the combined molecular approaches of these methods remain a suitable alternative to efficiently subtyping S. Enteritidis in the absence of high-resolution genotyping methods and these results may serve as a baseline study for development of mitigation strategies.

Detection and characterization of multidrug-resistant Salmonella enterica serovar Infantis as an emerging threat in poultry farms of Faisalabad, Pakistan

AIMS

The aim of this study was the molecular identification of Salmonella enterica serovar Infantis (S. Infantis) isolated from poultry samples and their antimicrobial resistance and virulence profiling.

METHODS AND RESULTS

A total of 149 isolates, belonging to genus Salmonella, originally isolated from 340 suspected poultry post mortem specimens reported by us earlier were preliminary identified as Salmonella by biochemical methods and confirmed by polymerase chain reaction targeting genus-specific gene invA. Targeting serovar-specific gene fragment (fljB) resulted in confirmation of 54 isolates as S. Infantis which were further confirmed by sequencing of 16S RNA and fljB genes. Swimming and swarming motilities were detected in 98·1 and 11·1% isolates respectively. Phenotypic disc diffusion assay against 23 antimicrobial agents showed the highest resistance against pefloxacin (PEF) (94·4%), chloramphenicol (83·3%) and imipenem (77·7%) while 5·3% isolates showed extended-spectrum β-lactamase production. Fifty-nine genes reported for antimicrobial resistance and 12 for conferring virulence were targeted. The most prevalent resistance gene for aminoglycosides was aadA (42·3%), for quinolone resistance determining region parE (62·5%), for penicillin's Int1 (62·9%), for chloramphenicol cat3 (66·1%) and for beta-lactams bla_{TEM -1} (44·4%). Among efflux pump coding genes, armA showed highest (74·2%) prevalence and for virulence, a high prevalence of SopE (89·2%) showed the zoonotic potential of the isolates. The activity of efflux pumps was detected through Ethidium Bromide-agar method.

CONCLUSIONS

Poultry could act as reservoirs of multidrug resistance Salmonella.

SIGNIFICANCE AND IMPACT OF THE STUDY

We firstly report the prevalence and molecular characterization of virulence/drug resistance in S. Infantis from this region and the results may contribute to designing precisely targeted therapy. This study has also highlighted the possible emergence of S. Infantis with zoonotic potential.

Characteristics of third-generation cephalosporin-resistant Salmonella from retail chicken meat produced by integrated broiler operations

Integrated broiler operations, which control and operate vertically through all phases of the chicken industry, have applied biosecurity and sanitation practices, housing technologies, feeding regimens, and antibiotic applications in different ways to improve food safety. The objective of this study was to compare the prevalence and antimicrobial resistance profiles of Salmonella isolates recovered from 6 different integrated broiler operations and to analyze the characteristics of extended-spectrum β-lactamase (ESBL)- and plasmid-mediated AmpC β-lactamase (pAmpC)-producing Salmonella isolates. Among 336 chicken meat samples, 57 were observed to be positive for Salmonella. However, the prevalence varied from 6.8% to 45.8% in chicken meat, indicating variations in Salmonella occurrence among the operations. Salmonella Albany was the dominant serovar, followed by Salmonella Virchow. In the antimicrobial resistance test, nalidixic acid-resistant isolates were the most prevalent (73.7%), followed by isolates resistant to ampicillin (49.1%) and tetracycline (42.1%). Among 14 third-generation cephalosporin-resistant isolates, 9 (64.3%) ESBL/pAmpC-producing isolates were only obtained from 2 operations: blaCTX-M-15 (n = 7) and blaCTX-M-79 (n = 1) for ESBL genes and blaCMY-2 (n = 1) for pAmpC. All ESBL/pAmpC-positive isolates exhibited high minimum inhibitory concentrations (≥128 μg/mL) of most cephalosporins and showed multidrug resistance. The transfer of ESBL/pAmpC genes was confirmed in transconjugants, which had the same genes and similar resistance patterns as those of the donor. Our findings suggest that Salmonella with resistance to third-generation cephalosporins can now be found in association with integrated broiler operations, providing data to support the development of monitoring and prevention programs for the development and spread of antimicrobial resistance in integrated broiler operations.

Antibiogram and genetic diversity of Salmonella enterica with zoonotic potential isolated from morbid native chickens and pigeons in Egypt

AIMS

This study investigated the possible role of Fayoumi chickens and pigeons in the transmission of multidrug resistant (MDR) Salmonella with zoonotic potential.

METHODS AND RESULTS

Morbid Fayoumi chickens (70) and pigeons (30) were examined to detect the prevalence and antibiotic resistance of Salmonella and to detect and sequence sodC-1 gene as a zoonotic and phylogenetic marker. Salmonella isolates were detected in 14·3 and 20% of the examined Fayoumi chickens and pigeons, respectively. Salomonella subspecies salamae (43·8%) and S. subspecies enterica serovar Bukuru (31·3%) were the most prevalent isolates. All tested Salmonella isolates were MDR to at least five classes of antibiotics. S. salamae and S. Bukuru isolates that carried bla_TEM , qnrS, aadA2 and floR genes expressed phenotypic resistance to cefotaxime, ciprofloxacin, streptomycin and chloramphenicol, respectively. The aacC gene was detected in one of each S. salamae and S. Bukuru isolate, although only the S. Bukuru isolate showed phenotypic resistance to gentamicin. The sequence analysis of the sodC-1 gene from Salmonella isolates showed clear inter- and intra-subspecies phylogenetic segregation.

CONCLUSIONS

Fayoumi chickens and pigeons could act as reservoirs of MDR Salmonella.

SIGNIFICANCE AND IMPACT OF THE STUDY

This study highlights the possible emergence of Salmonella subspecies salamae with zoonotic potential.

Prevalence, antibiotic resistance, and extended-spectrum and AmpC β-lactamase productivity of Salmonella isolates from raw meat and seafood samples in Ho Chi Minh City, Vietnam

Salmonellosis is a type of foodborne disease caused by Salmonella enterica and is a frequent cause of childhood diarrhea in Vietnam. Of particular concern is the dissemination of multidrug-resistant Salmonella, as extended-spectrum β-lactamase (ESBL)-positive isolates were recently detected in children in Vietnam. In the present study, the prevalence and antibiotic resistance of Salmonella isolates obtained from 409 raw meat and seafood samples collected between October 2012 and March 2015 from slaughterhouses, wholesale fish market, and retail markets in Ho Chi Minh City, Vietnam were examined. A high rate of Salmonella contamination was detected in the pork (69.7%), poultry (65.3%), beef (58.3%), shrimp (49.1%), and farmed freshwater fish samples (36.6%). A total of 53 Salmonella serovars were found, of which S. Rissen, S. Weltevreden, S. London, S. Anatum, S. Typhimurium, and S. Corvallis were the most prevalent. In addition, 4 monophasic S. Typhimurium strains were identified using a PCR method for the detection of a specific IS200 fragment within the fliB-fliA intergenic region. The Salmonella isolates had a high prevalence (62.2%) of resistance to antimicrobial agents, particularly tetracycline (53.3%), ampicillin (43.8%), chloramphenicol (37.5%), and trimethoprim/sulfamethoxazole (31.3%). Isolates with resistance to three or more classes of antimicrobials were found (41.1%). Especially, isolates such as S. monophasic Typhimurium, S. Schwarzengrund, S. Indiana, S. Newport, S. Saintpaul and S. Bovismorbificans exhibited resistance to 6 classes of antimicrobials (3.3%). All 7 S. Indiana strains were resistant to between 4 and 6 classes of antimicrobials, including ciprofloxacin, which is commonly used for the treatment of human Salmonella infections. Two fish isolates were confirmed to be CTX-M-55 ESBL-producing Salmonella serovars Bovismorbificans and Newport, and five CMY-2 AmpC-producing Salmonella isolates of serovars Braenderup (4) and Typhimurium (1) were detected in poultry samples. The findings from this study, which is the first report of ESBL- and AmpC-producing Salmonella isolates from food in Vietnam, indicate that multidrug-resistant Salmonella are widely disseminated not only in meats, but also in seafood, within the food distribution system of Vietnam. The presence of these multidrug-resistant strains is a public health concern and suggests that the use of antimicrobial agents in both humans and animals in Vietnam should be tightly controlled.