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Pet food is increasingly recognized as a significant vehicle for the transmission of foodborne pathogens to humans. The intimate association between pets and their owners, coupled with the rising trend of feeding pets raw and unprocessed foods, contributes substantially to this issue. Salmonella contamination in pet food can originate from raw materials and feed ingredients, the processing environment, and postprocessing handling and applications. The absence of standardized postprocessing pathogen mitigation steps in the production of dry kibble and treats, along with the lack of validated heat and chemical interventions in raw pet foods, renders pet food susceptible to contamination by pathogens such as Salmonella, Listeria, E. coli, etc. Pets can then serve as carriers of Salmonella, facilitating its transmission to pet owners. Since 1999, there have been over 117 recalls of pet foods due to Salmonella contamination in the United States, with 11 of these recalls linked to human outbreaks. Notably, 5 of the 11 human outbreaks involved multidrug‐resistant Salmonella strains. Various antimicrobial interventions, including high‐pressure processing, ozone, irradiation, chemical treatments such as organic acids and acidulants, plant‐derived antimicrobials, and biological interventions such as bacteriophages, have proven effective against Salmonella in pet foods. This review aims to summarize the prevalence of Salmonella in different types of pet foods, identify common sources of contamination, outline reported outbreaks, and discuss control measures and the regulatory framework governing pet food safety. [ABSTRACT FROM AUTHOR]

Surface-growing antibiotic-resistant pathogenic Salmonella is emerging as a global health challenge due to its high economic loss in the poultry industry. Their pathogenesis, increasing antimicrobial resistance, and biofilm formation make them challenging to treat with traditional therapy. The identification of antimicrobial herbal ingredients may provide valuable solutions to solve this problem. Therefore, our aim is to evaluate the potency of nano garlic as the alternative of choice against multidrug-resistant (MDR) Salmonella isolates using disc diffusion and microdilution assays. Then, checkerboard titration in trays was applied, and FIC was measured to identify the type of interaction between the two antimicrobials. A disc diffusion assay revealed that neomycin was the drug of choice. The range of nano garlic MIC was 12.5–25 μg/ml, while the neomycin MIC range was 32–64 μg/ml. The FIC index established a synergistic association between the two tested drugs in 85% of isolates. An experimental model was used including nano garlic and neomycin alone and in combination against Salmonella infection. The combination therapy significantly improved body productivity and inhibited biofilm formation by more than 50% down regulating the CsgBAD, motB, and sipA operons, which are responsible for curli fimbriae production and biofilm formation in Salmonella serotypes. [ABSTRACT FROM AUTHOR]

Non-typhoidal salmonellosis (NTS) caused by ingesting Salmonella enterica contaminated food or drink remains a major bacterial foodborne disease. Clinical outcomes of NTS range from self-limited gastroenteritis to life-threatening invasive NTS (iNTS). In this study, we isolated Salmonella spp. from the stool and blood of patients hospitalized at Maharaj Nakorn Chiang Mai Hospital, Chiang Mai, Thailand, between 2016–2021 (a total of 395 cases). Then, serovar Typhimurium and Enteritidis were identified and further characterized by multiplex PCR, and multi-locus sequence typing. Our data show that multidrug resistance (MDR) sequence type 34 (ST34) and ST11 are the predominant sequence types for serovars Typhimurium and Enteritidis, respectively. Most S. Typhimurium ST34 lacks spvB, and most S. Enteritidis ST11 harbor sseI, sodCI, rpoS and spvB genes. NTS can be found in a wide range of ages, and anemia could be a significant factor for S. Typhimurium infection (86.3%). Both S. Typhimurium (6.7%) and S. Enteritidis (25.0%) can cause iNTS in immunocompromised patients. S. Typhimurium conferred MDR phenotype higher than S. Enteritidis with multiple antibiotic resistance indexes of 0.22 and 0.04, respectively. Here, we characterized the important S. Typhimurium, S. Enteritidis, and human clinical factors of NTS within the region. [ABSTRACT FROM AUTHOR]

The prevalence and persistent outbreaks of multidrug-resistant (MDR) Salmonella in low-income countries have received growing attention among the public and scientific community. Notably, the excessive use of antibiotics in chicken feed for the purpose of treatment or as prophylaxis in the poultry industry have led to a rising rate of antimicrobial resistance. Therefore, this study aimed to determine the presence of antimicrobial-resistant Salmonella species and its mobile genetic elements from soil and effluent samples of 33 randomly selected poultry farms in Selangor, Malaysia. Salmonella species were isolated on selective media (CHROMagar™ Salmonella). VITEK® 2 system was used to identify the isolates and their antimicrobial susceptibility. Subsequently, eight isolates were subjected to the whole genome sequencing (WGS). Based on the results, Salmonella spp. was detected in 38.1% (24/63) of samples, with the highest resistance to ampicillin (62.5%), followed by ampicillin/sulbactam (50.0%) and ciprofloxacin (45.8%). Meanwhile, the identified serovars were Salmonella enterica subspecies enterica serovar Weltevreden (S. Weltevreden), S. Jedburgh, and S. Brancaster. The most prevalent resistance genes detected include qnrS1, blaTEM-176, dfrA14, and tet(A). The IncX1 plasmid, with encoded resistance genes, was also detected in four isolates. Furthermore, mutations in the quinolone resistant-determining regions (QRDR) were discovered, specifically in the gyrA, gyrB, and parC genes. In short, surveillance such as continuous monitoring of antimicrobial resistance and emerging trends in resistance patterns through farm environmental samples could provide information to formulate public health interventions for effective infection prevention and disease control. [ABSTRACT FROM AUTHOR]

Non-typhoidal salmonellosis (NTS) caused by ingesting Salmonella enterica contaminated food or drink remains a major bacterial foodborne disease. Clinical outcomes of NTS range from self-limited gastroenteritis to life-threatening invasive NTS (iNTS). In this study, we isolated Salmonella spp. from the stool and blood of patients hospitalized at Maharaj Nakorn Chiang Mai Hospital, Chiang Mai, Thailand, between 2016–2021 (a total of 395 cases). Then, serovar Typhimurium and Enteritidis were identified and further characterized by multiplex PCR, and multi-locus sequence typing. Our data show that multidrug resistance (MDR) sequence type 34 (ST34) and ST11 are the predominant sequence types for serovars Typhimurium and Enteritidis, respectively. Most S. Typhimurium ST34 lacks spvB, and most S. Enteritidis ST11 harbor sseI, sodCI, rpoS and spvB genes. NTS can be found in a wide range of ages, and anemia could be a significant factor for S. Typhimurium infection (86.3%). Both S. Typhimurium (6.7%) and S. Enteritidis (25.0%) can cause iNTS in immunocompromised patients. S. Typhimurium conferred MDR phenotype higher than S. Enteritidis with multiple antibiotic resistance indexes of 0.22 and 0.04, respectively. Here, we characterized the important S. Typhimurium, S. Enteritidis, and human clinical factors of NTS within the region.

The prevalence and persistent outbreaks of multidrug-resistant (MDR) Salmonella in low-income countries have received growing attention among the public and scientific community. Notably, the excessive use of antibiotics in chicken feed for the purpose of treatment or as prophylaxis in the poultry industry have led to a rising rate of antimicrobial resistance. Therefore, this study aimed to determine the presence of antimicrobial-resistant Salmonella species and its mobile genetic elements from soil and effluent samples of 33 randomly selected poultry farms in Selangor, Malaysia. Salmonella species were isolated on selective media (CHROMagar™ Salmonella). VITEK® 2 system was used to identify the isolates and their antimicrobial susceptibility. Subsequently, eight isolates were subjected to the whole genome sequencing (WGS). Based on the results, Salmonella spp. was detected in 38.1% (24/63) of samples, with the highest resistance to ampicillin (62.5%), followed by ampicillin/sulbactam (50.0%) and ciprofloxacin (45.8%). Meanwhile, the identified serovars were Salmonella enterica subspecies enterica serovar Weltevreden (S. Weltevreden), S. Jedburgh, and S. Brancaster. The most prevalent resistance genes detected include qnrS1, blaTEM-176, dfrA14, and tet(A). The IncX1 plasmid, with encoded resistance genes, was also detected in four isolates. Furthermore, mutations in the quinolone resistant-determining regions (QRDR) were discovered, specifically in the gyrA, gyrB, and parC genes. In short, surveillance such as continuous monitoring of antimicrobial resistance and emerging trends in resistance patterns through farm environmental samples could provide information to formulate public health interventions for effective infection prevention and disease control.

Available data showed that the recovery of multidrug-resistant and biofilm-producing Salmonella spp. from chicken meat is still scanty in Nigeria. Consequently, this study aimed to characterize the probable multidrugresistant and biofilm producing Salmonella spp. prevalent in chicken meat vended in southern Nigerian markets. About 240 randomly sampled chilled raw chicken meats were collected from open markets in Delta, Edo, Ekiti and Ondo States, and then were analysed for detecting the presence of Salmonella spp.; using rinse centrifugation-plating technique, serological examination and 16S rRNA gene sequencing. The confirmed Salmonella isolates were tested for multidrug-resistance and biofilm formation using Kirby Bauer disc diffusion test and tissue culture plates, respectively. Out of 229 presumptively examined Salmonella isolates, 52 isolates were confirmed as Salmonella spp., while 46 isolates were recorded as multidrug-resistant. The main serotypes recovered were; S. enterica subsp. enterica serovar Typhimurium (35/52; 67.31%), and S. enterica subsp. enterica serovar Enteritidis (17/52; 32.69%). Biofilm characterization of the recovered Salmonella isolates were; strong (OD > 0.240), 6 (11.5 %); moderate (0.120-0.240), 13 (25.0 %); weak (OD < 0.120), 19 (36.5 %), and nonbiofilm producers (OD < 0.120), 14 (26.9 %). This study showed that multidrug-resistant and biofilm-producing Salmonella spp. were prevalent in raw chicken meat; vended within southern Nigerian open markets. Thus, there is an urgent need for relevant regulatory agencies to enforce consumer's safety.

The emergence of antibiotic resistance and biofilm formation among Salmonella strains, especially in chicken meat, poses substantial risks to economic and public health. To mitigate these challenges, we explored interventions and biofilm inhibition strategies against multidrug-resistant serovars (B, C1, and D groups), by Salmonella phage SEP4, an isolate with broad host-spectrum. The morphological and genomic analyses classified it as a member of the Siphoviridae family with an icosahedral head of 124.56 ± 8.9 nm diameter and 66.28 ± 2.01 nm tail length, respectively. Phage SEP4 displayed robust survivability over a pH range of 3–10 and temperatures from 30 °C to 60 °C. Phage adsorption peaked at 73.20% in 15 min, with a burst size of 119 PFU/CFU at optimal MOI-1. Moreover, a linear double-stranded DNA genome of 41,828 bp, characterized by 49.84% GC content and putative 57 open reading frames (ORFs), and lacked antibiotic or virulence factor genes. Anti- Salmonella phage efficacy demonstrated a significant reduction in viable cell counts at 25 °C compared to 4 °C against tested MDR strains in food models. The bactericidal activity of phage SEP4 ranged from 14% to 46% and 25%–33.8% against host at MOI-1 and 100, while 22%–37% for other MDR strains. Simultaneously, SEP4 inhibited the growth of matured biofilms on lettuce leaves and chicken surfaces, achieving complete reduction within 4–6 h. SEM images confirmed the drastic destruction of cohesive biofilm architectures by phage treatment. The findings show that phage SEP4 has promising potential as a biocontrol agent, ensuring food safety by controlling MDR Salmonella contaminations and associated biofilms. • Isolated phage SEP4 was scrutinized by MDR salmonella lytic susceptibility. • Bactericidal activity of phage SEP4 in food matrices was highly significant. • Phage SEP4 effectively eradicated the matured biofilms on chicken breast surfaces. • Phage SEP4 DNA lacks toxic, antibiotic-resistant genes, and shows lytic lifecycle. [ABSTRACT FROM AUTHOR]

Salmonella spp. is widely considered one of the most important zoonotic pathogens worldwide. The close contact between reptiles and their owners provides favourable conditions for the transmission of zoonotic pathogen infections, and ~6% of human salmonellosis cases are acquired after direct or indirect contact with reptiles. Moreover, antimicrobial resistance is one of the most important health threats of the twenty-first century and has been reported in Salmonella strains isolated from pet reptiles, which could entail therapeutic consequences for their owners and breeders. The aim of this study was to assess Salmonella carriage by pet reptiles in pet shops and households, and their role in the transmission of antimicrobial resistance, to inform the owners about the possible risks factors. During the period between January 2019 and December 2019, 54 reptiles from pet shops and 69 reptiles from households were sampled in the Valencian Region (Eastern Spain). Three different sample types were collected from each reptile: oral cavity, skin, and cloacal swabs. Salmonella identification was based on ISO 6579-1:2017 (Annex D), serotyped in accordance with Kauffman-White-Le-Minor technique, and antibiotic susceptibility was assessed according to Decision 2013/652. The results of this study showed that 48% of the pet reptiles examined from households and pet shops carry Salmonella spp. All the strains isolated presented resistance to at least one antibiotic, and 72% were multidrug-resistant strains, the most frequently observed resistance patterns being gentamicin-colistin and gentamicin-colistin-ampicillin. The present study demonstrates that pet reptiles could be a source of human multidrug-resistant Salmonella infection. In this context, the most optimal prevention of multidrug-resistant Salmonella infections necessarily involves strict control of the sanitary status of reptile pet shops and hygienic handling by the individual owners at home.

Introduction: Enteric-fever is a major public-health problem in developing countries emerging as multidrug-resistant, Nalidixic-acid resistant and extremely drug-resistant Salmonella (Pakistan, 2016), has intensified the use of WHO watch/reserve group antimicrobials such as azithromycin and meropenem. Methods: This ambispective-study was conducted on 782 non-repeat blood-culture isolates of S. Typhi, S. Paratyphi A and S. Paratyphi B obtained from 29,184 blood cultures received at a 1000-bedded tertiary-care hospital of North-India from 2011–2017. Identification and antibiograms were obtained by Vitek-2 compact and Kirby-Bauer’s disc diffusion with resistance to ampicillin, chloramphenicol and cotrimoxazole being labeled as multidrug-resistant. Decreased ciprofloxacin-susceptibility and ciprofloxacin-resistance were defined as MIC 0.125–0.5 and >1 μg/ml. Results: S. Typhi and S. Paratyphi A in a ratio of 3.9:1 were seen between July–September predominantly distributed between 6–45 year age group. Resistance to co-trimoxazole, chloramphenicol, ceftriaxone and azithromycin was 6.1%, 13.8%, 16.1 and 5.78% respectively. Multidrug-resistant S. typhi and S. paratyphi A were 2.73% and 1.91% respectively. Conclusion: Enteric-fever is a major public-health problem in India. Emergence of multidrug-resistant, Nalidixic-acid resistant and extremely-drug resistant Salmonella mandates ongoing surveillance for targeted empirical therapy and containment of spread. Repeated epidemics call for water, sanitation, hygiene and vaccination strategies to sustain herd-immunity.

Abstract The present study investigated the distribution, antimicrobial susceptibility profiles, serotypes and genotypes of Salmonella isolates from a slaughterhouse (including lairage and slaughter line) and its downstream retail markets to determine the main sources of Salmonella contamination in retail chicken meat. Positive identification rates in the slaughterhouse and retail markets were 9.5% (81/852) and 41.8% (69/165), respectively. Among the Salmonella serovars identified, S. Albany was the most prevalent but other serovars including S. Montevideo and S. Virchow were also present prominently. Antimicrobial susceptibility testing revealed that the highest antimicrobial resistance rate was against nalidixic acid (139/150, 92.7%), that 56.7% (85/150) isolates were multidrug-resistant (MDR), and that the resistance profile of 20.7% (31/150) isolates was ACSSuT (ampicillin, chloramphenicol, streptomycin, sulfonamides and tetracycline). Ten virulence genes were detected in 69 isolates from retail chicken meat; the Salmonella pathogenicity island genes inv A, hil A, sip A, sop B, sop D, ssr A, and ssa R were present in most of the isolates (94.2%–100%). Based on analysis of pulsed-field gel electrophoresis (PFGE) results, our findings indicated that MDR isolates could be transmitted from slaughterhouse to its downstream retail markets. In addition, the present study indicates three possible routes of Salmonella contamination in retail chicken meat, including initial presence, cross-contamination from carrier broilers slaughtered on the same day, and contamination from resident flora in slaughterhouse, with the last route being the most common in the present study. Highlights • AMR and genotype of Salmonella from slaughterhouse and markets were conducted. • Frequent cross-contamination in slaughterhouse has been identified. • The major causative contamination step in slaughter-line has been confirmed. • Frequent propagation of MDR Salmonella from slaughterhouse to market has been found. • Three routes of MDR Salmonella contamination in retail meat have been confirmed. [ABSTRACT FROM AUTHOR]

Salmonella is estimated to cause 1.2 million cases of human foodborne illness each year in the United States, and pigs can often be asymptomatically colonized with Salmonella (>50% of farms). Recent reports state that 18.3% of Salmonella enterica serovar Typhimurium (S. Typhimurium) isolates are resistant to ≥3 antimicrobial classes, and multidrug resistant (MDR) strains are associated with an increased hospitalization rate and other complications. Chlortetracycline is commonly used in swine production to prevent/treat various diseases; therefore, chlortetracycline treatment of pigs unknowingly colonized with MDR Salmonella may have collateral effects on Salmonella (and other gut bacteria). In this study, we determined the effect of in-feed chlortetracycline (400 g/ton) on shedding and colonization of pigs challenged with an MDR S. Typhimurium DT104 strain (n = 11/group). We also assessed the impact on the fecal microbiota over the 12-day experimental period and on the ileum, cecum, and tonsil microbiota at 7 days post-inoculation (dpi). In MDR S. Typhimurium-inoculated pigs, chlortetracycline administration significantly increased fecal shedding at 2 dpi (+1.4 log10 CFU/g; P < 0.001) and enhanced tonsil colonization (+3.1 log10 CFU/g; P < 0.001). There were few major alterations detected in the gut or tonsillar microbiota of pigs treated with MDR S. Typhimurium and/or chlortetracycline. The tonsillar transcriptome was largely unaffected despite increased colonization by MDR S. Typhimurium following inoculation of the chlortetracycline-treated pigs. These results highlight that chlortetracycline administration can enhance shedding and colonization of MDR S. Typhimurium in pigs, which could increase the risk of environmental dissemination of MDR Salmonella strains. Importance Salmonella is an important cause of foodborne illness in North America, and pork products are associated with sporadic cases and outbreaks of human salmonellosis. Isolates of Salmonella may be resistant to multiple antibiotics, and infections with multidrug-resistant (MDR) Salmonella are more difficult to treat, leading to increased hospitalization rates. Swine operations commonly use antimicrobials such as chlortetracycline to prevent/treat infections, which may have collateral effects on pig microbial populations. Recently, we demonstrated that chlortetracycline induces the expression of genes associated with pathogenesis and invasion in MDR Salmonella enterica serovar Typhimurium in vitro. In our current study, we show increased tonsillar colonization and fecal shedding of a MDR S. Typhimurium DT104 strain from pigs administered chlortetracycline. Therefore, pigs unknowingly colonized with multidrug-resistant Salmonella and receiving chlortetracycline for an unrelated infection may be at a greater risk for disseminating MDR Salmonella to other pigs and to humans through environmental or pork product contamination. [ABSTRACT FROM AUTHOR]

The increasing prevalence of multidrug-resistant (MDR) Salmonella is a serious public health threat. Intervention strategies available to control Salmonella mostly target Salmonella enterica serovars Typhimurium and Enteritidis, and little has been investigated to control serovars in serogroup C, such as S. enterica serovar Thompson, despite their increasing prevalence. Here, we isolated phages targeting MDR S. Thompson and characterized the antimicrobial activities of MSP1 phage, a virulent phage with a broad host range. MSP1 phage strongly infected S. Thompson and S. Mbandaka isolates from retail chicken and also other serovars, including Dublin, Enteritidis, Heidelberg, Paratyphi, and Typhimurium. MSP1 phage was able to inhibit the biofilm formation on stainless steel and glass formation by around 42.7–47.9 %. MSP1 phage was robust to withstand wide ranges of pH (4–12) and temperature (30–60 °C), and no genes associated with antibiotic resistance and virulence were found in the phage genome, suggesting that this phage is suitable for food application. When MSP1 phage was tested on foods (chicken meat and milk), MSP1 phage significantly reduced the level of MDR S. Thompson below the detection limit. Our findings suggest that MSP1 phage is a promising antimicrobial agent for the control of food contamination by MDR S. Thompson. [Display omitted] • A broad host range phage MSP1 can effectively control S. Thompson. • MSP1 phage was able to inhibit the biofilm formation. • MSP1 phage decreased MDR S. Thompson contamination on chicken meat and milk. • MSP1 phage showed the potential to control food contamination by MDR S. Thompson. [ABSTRACT FROM AUTHOR]

This study aimed to determine the frequency and characterization of Salmonella isolates from food-producing animals and human diarrheal samples in Shiraz, Iran. Overall, 105 Salmonella isolates were obtained from chicken meat (70/100, 70.0%), beef (19/100, 19.0%), lamb (11/100, 11.0%), and human stool (5/295, 1.7%). S. Infantis (40.9%), S. Enteritidis (29.5%), and S. Paratyphi B (8.6%) were the most prevalent serotypes. Totally 59.1% of the isolates were multidrug-resistant. High resistance to nalidixic acid (67.6%), tetracycline (62.9%), and trimethoprim-sulfamethoxazole (42.3%) were observed. Mutations in the gyr A and par C genes were detected in nalidixic acid-resistant isolates from chicken meat and human stool. No qnr A, qnr B or qnr S genes were detected. The bla TEM and bla CMY-2 genes were detected in β-lactam-resistant isolates from beef and lamb. Despite the high genetic diversity of PFGE patterns, some isolates from different sources and times showed identical PFGE patterns suggesting specific Salmonella species circulate between various sources over time. • Salmonella isolates were recovered from chicken, beef, lamb, and human stool. • A high frequency of MDR isolates was recovered from chicken meat. • S. Infantis, and S. Enteritidis were the most frequent serotypes. • bla TEM , bla CMY-2 genes and mutations in gyr A and par C genes were observed. • Isolates with identical PFGE patterns were recovered from various sources and times. [ABSTRACT FROM AUTHOR]

Abstract: This study compared lactic acid resistance of individual strains of wild-type and rifampicin-resistant non-O157 Shiga toxin-producing Escherichia coli (STEC) and of susceptible and multidrug-resistant (MDR) and/or MDR with acquired ampC gene (MDR-AmpC) Salmonella against E. coli O157:H7. After inoculation of sterile 10% beef homogenate, lactic acid was added to a target concentration of 5%. Before acid addition (control), after acid addition (within 2 s, i.e. time-0), and 2, 4, 6 and 8 min after addition of acid, aliquots were removed, neutralized, and analyzed for survivors. Of wild-type and of rifampicin-resistant non-O157 STEC strains, irrespective of serogroup, 85.7% (30 out of 35 strains) and 82.9% (29 out of 35 strains), respectively, reached the detection limit within 0–6 min. Of Salmonella strains, 87.9% (29 out of 33 isolates) reached the detection limit within 0–4 min, irrespective of antibiotic resistance phenotype. Analysis of non-log-linear microbial survivor curves indicated that non-O157 STEC serogroups and MDR and susceptible Salmonella strains required less time for 4D-reduction compared to E. coli O157:H7. Overall, for nearly all strains and time intervals, individual strains of wild-type and rifampicin-resistant non-O157 STEC and Salmonella were less (P < 0.05) acid tolerant than E. coli O157:H7. [Copyright &y& Elsevier]

This study compared biofilm formation by 7 serogroups of pathogenic Escherichia coli and 2 or 3 phenotypes of Salmonella (susceptible, multidrug-resistant [MDR], and/or multidrug resistant with ampC gene [MDR-AmpC]). One-week mature biofilms were also exposed to water, quaternary ammonium compound-based (QAC), and acid-based (AB) sanitizers. Seven groups (strain mixture) of above-mentioned pathogens were separately spot-inoculated onto stainless steel coupons surfaces for target inoculation of 2 log CFU/cm2, then stored statically, partially submerged in 10% nonsterilized meat homogenate at 4, 15, and 25 °C. Biofilm cells were enumerated on days 0, 1, 4, and 7 following submersion in 30 mL for 1 min in water, QAC, and AB. Counts on inoculation day ranged from 1.6 ± 0.4 to 2.4 ± 0.6 log CFU/cm2 and changed to 1.2 ± 0.8 to 1.9 ± 0.8 on day 7 at 4 °C with no appreciable difference among the 7 pathogen groups. After treatment with QAC and AB on day 7, counts were reduced ( P < 0.05) to less than 0.7 ± 0.6 and 1.2 ± 0.5, respectively, with similar trends among pathogens. Biofilm formation at higher temperatures was more enhanced; E. coli O157:H7, as an example, increased ( P < 0.05) from 1.4 ± 0.6 and 2.0 ± 0.3 on day 0 to 4.8 ± 0.6 and 6.5 ± 0.2 on day 7 at 15 and 25 °C, respectively. As compared to 4 °C, after sanitation, more survivors were observed for 15 and 25 °C treatments with no appreciable differences among pathogens. Overall, we observed similar patterns of growth and susceptibility to QAC and AB sanitizers of the 7 tested pathogen groups with enhanced biofilm formation capability and higher numbers of treatment survivors at higher temperatures. [ABSTRACT FROM AUTHOR]

Fifty-nine commercial dairy farms were sampled 7 times over 15 to 21 mo to determine the role of animal movement, including off-farm rearing of heifers, in the interherd transmission of multidrug-resistant (MDR) Salmonella spp. Farm management data were collected by on-site inspections and questionnaires on herd management practices before and after the study. Forty-four percent (26/59) of herds did not acquire any new MDR Salmonella strains. The number of newly introduced MDR Salmonella strains acquired by the remaining 56% (33/59) of herds ranged from 1 to 8. Logistic regression models indicated that off-farm heifer raising, including contract heifer raising where heifers commingle with cattle from other farms [commingled heifers, odds ratio (OR) = 8.9, 95% confidence interval (CI): 2.4, 32.80], and herd size per 100-animal increment (herd size, OR = 1.04, 95% CI, 1.01, 1.05) were significantly associated with the introduction of new MDR Salmonella strains. The negative binomial regression similarly revealed that commingled heifers [relative risk (RR) = 2.3, 95% CI: 1.1, 4.7], herd size per 100 animals (RR = 1.02, 95% CI, 1.01, 1.03), and a history of clinical salmonellosis diagnosed before the study (RR = 2.5, 95% CI, 1.3, 5.0) were significantly associated with the number of new MDR Salmonella strains that were introduced. Factors not associated with the introduction of new MDR Salmonella strains were housing of heifers and cows in the same close-up pen, a common hospital-maternity pen, and the number of purchased cattle. This study highlights the role of animal movement in the interherd transmission of MDR Salmonella spp. [ABSTRACT FROM AUTHOR]

A longitudinal observational study of 59 dairy herds was conducted in Washington State to estimate the rate of introduction of new multidrug-resistant (MDR) Salmonella enterica strains onto commercial dairy herds. Samples were collected on these herds over 7 visits separated by intervals of 2 to 4 mo over a period of 15 to 21 mo. Samples were cultured for Salmonella spp. and serogroup, serovar, and antimicrobial susceptibility patterns were identified for MDR Salmonella isolates. Fingerprinting generated by pulsed-field gel electrophoresis (PFGE) using XbaI restriction enzyme digestion generated genotyping profiles for all MDR isolates identified in the study. The rate of new MDR Salmonella strain introduction was 0.9 per herd-year (95% confidence interval: 0.6-1.4). The rates for the most commonly introduced MDR Salmonella serovars were 0.4/herd-year for Typhimurium, 1.2/herd-year for Newport, and 0.1/herd-year for Dublin. Thirty-three of 59 herds (56%) had at least one new MDR Salmonella introduction during the study period. The number of new MDR Salmonella strains acquired by dairy herds ranged from zero to 8. Thirteen of the 59 herds had a history of clinical salmonellosis. Among these 13 herds, 6 herds acquired new MDR Salmonella strains, although these strains were different than historical clinical strains. These data indicate that acquisition of new MDR Salmonella strains by dairy herds was a common event in participating herds, although the number of strains introduced varied greatly among herds. [ABSTRACT FROM AUTHOR]

This study aimed to assess Salmonella spp. prevalence in aquaculture Nile tilapia commercialized in the Federal District, Brazil, and determine the antimicrobial resistance profile of the isolates. Fifty-seven Salmonella spp. strains were isolated from 101 samples of fresh tilapia fillets collected in the Federal District, Brazil. These isolates were subjected to antimicrobial susceptibility testing by the Kirby-Bauer disk diffusion method and analyzed for the presence of blaCTX , tetB , sul2 , and floR resistance genes. The Salmonella spp. prevalence in fresh tilapia fillets was 45.5%; that is, 46 of 101 samples were positive for the InvA gene. The antimicrobial resistance profile showed high resistance rates for amoxicillin/clavulanic acid (87.7%), tetracycline (82.5%), sulfonamide (57.9%), and chloramphenicol (26.3%). Additionally, 56.1% of Salmonella spp. isolates were multidrug-resistant (MDR) isolates. The beta-lactam-resistant gene blaCTX was identified in 66.7% of isolates, the tetracycline resistance gene tetA in 54.4%, and the chloramphenicol resistance gene floR in 50.9%, while the sulfonamide resistance gene sul2 was present in 49.1%. The results revealed that tilapia fillets were highly contaminated with MDR Salmonella . These Salmonella spp. strains carried multiple antimicrobial resistance genes, which might facilitate their dissemination to consumers along the production chain. Hence, there is an evident need to control Salmonella in fish production systems to ensure public health.

The article discusses a study which examines an Salmonella enterica serovar Typhimurium strain 72-21880-11 found from the faeces of a cow in Denmark in 2000. Researchers found that the cow was resistant from chloramphenicol/florfenicol, streptomycin/spectinomycin and tetracycline. They concluded that the unusual resistance pattern of the strain could mean that the genetic variations happened within the In104 complex integron.

Abstract: The Red recombinase system of bacteriophage Lambda has been used to inactivate chromosomal genes in bacteria using PCR products. In this study, we describe the replacement of the ampicillin resistance marker of helper plasmids pKD46 and pCP20 by a gentamicin resistance gene to disrupt chromosomal genes and then to eliminate FRT flanked resistance gene in multiple antibiotic-resistant Salmonella enterica strains. [Copyright &y& Elsevier]

This case report describes a 68-year-old male with recurrent multidrug-resistant Salmonella enterica serovar Typhimurium bacteremia acquired during travel abroad. He experienced a recurrence of bacteremia without a clear source and was successfully treated with 10 weeks of intravenous ertapenem. Post hoc genome sequencing revealed an isolate bearing class A, C, and D extended-spectrum β-lactamases (ESBLs). A review of English- and French-language literature since 2000 revealed eight publications that discussed recurrent S. enterica serovar Typhimurium bacteremia. Patients with multidrug-resistant S. enterica serovar Typhimurium should be monitored frequently for recrudescence, even in the absence of risk factors., Competing Interests: The authors have nothing to disclose., (Copyright © 2020, Association of Medical Microbiology and Infectious Disease Canada (AMMI Canada).)