Production of cytokines by mouse B cells: B lymphomas and normal B cells produce interleukin 10

We have examined a panel of murine Ly-1+ B lymphomas and purified normal murine peritoneal B cells separated into subsets on the basis of expression of the Ly-1 surface antigen, for their ability to produce cytokines. Where possible, we have used a combination of cytokine detection methods in order to compensate for differences in sensitivity and specificity, and the possibility of inhibitors masking an activity. All the lymphomas tested were shown to constitutively express TGF-beta and CSIF/IL-10. In addition, varying levels of IL-6, TNF-alpha and TNF-beta, and G-CSF, were demonstrable in most of the lymphomas, and variants of one lymphoma (CH12) additionally produced varying levels of IL-3, IL-4, and GM-CSF. FACS purified normal Ly-1+ and Ly-1- peritoneal B cells, were also shown to express RNA encoding CSIF/IL-10, IL-6, TNF-alpha and TNF-beta, and very low levels of G-CSF, following stimulation with LPS. These data were supported by the detection of IL-6 and CSIF/IL-10 in supernatants from LPS-stimulated Ly-1+ and Ly-1- B cells using specific immunoassays. None of the lymphomas or B cell preparations produced IL-1 alpha, IL-2, IL-5, IL-7, or IFN-gamma. The purity of our normal B cell populations was assessed by phenotypic analysis on the FACS and also by the disappearance of certain mRNA transcripts after purification, e.g. CD4, c-fms, GM-CSF, and IFN-gamma, most of which could be detected in LPS-stimulated total peritoneal cell populations. This suggested that our B cell purification method had reduced, to a level undetectable in our assays, contaminating T cells (CD4), macrophages (c-fms, GM-CSF), and NK cells (IFN-gamma). Absence of IL-3, IL-4, IL-5, and GM-CSF expression by LPS-stimulated Ly-1+ and Ly-1- B cells reduced the concern that contaminating peritoneal mast cells could account for the observed cytokine production. We therefore believe our data provide strong support for production of a subset of cytokines by LPS-stimulated normal B cells. Both the Ly-1+ B lymphomas and normal Ly-1+ and Ly-1- B cells appear capable of expressing IL-6, TNF-alpha, TNF-beta, and CSIF/IL-10.(ABSTRACT TRUNCATED AT 400 WORDS)

Cyp7b, a novel brain cytochrome P450, catalyzes the synthesis of neurosteroids 7alpha-hydroxy dehydroepiandrosterone and 7alpha-hydroxy pregnenolone

Steroids produced locally in brain (neurosteroids), including dehydroepiandrosterone (DHEA), influence cognition and behavior. We previously described a novel cytochrome P450, Cyp7b, strongly expressed in rat and mouse brain, particularly in hippocampus. Cyp7b is most similar to steroidogenic P450s and potentially could play a role in neurosteroid metabolism. To examine the catalytic activity of the enzyme mouse Cyp7b cDNA was introduced into a vaccinia virus vector. Extracts from cells infected with the recombinant showed NADPH-dependent conversion of DHEA (Km, 13.6 microM) and pregnenolone (Km, 4.0 microM) to slower migrating forms on thin layer chromatography. The expressed enzyme was less active against 25-hydroxycholesterol, 17beta-estradiol and 5alpha-androstane-3beta,17beta-diol, with low to undetectable activity against progesterone, corticosterone, and testosterone. On gas chromatography and mass spectrometry of the Cyp7b metabolite of DHEA the retention time and fragmentation patterns were identical to those obtained with authentic 7alpha-hydroxy DHEA. The reaction product also comigrated on thin layer chromatography with 7alpha-hydroxy DHEA but not with 7beta-hydroxy DHEA; when [7alpha-3H]pregnenolone was incubated with Cyp7b extracts the extent of release of radioactivity into the medium suggested that hydroxylation was preferentially at the 7alpha position. Brain extracts also efficiently liberated tritium from [7alpha-3H]pregnenolone and converted DHEA to a product with a chromatographic mobility indistinguishable from 7alpha-hydroxy DHEA. We conclude that Cyp7b is a 7alpha-hydroxylase participating in the synthesis, in brain, of neurosteroids 7alpha-hydroxy DHEA, and 7alpha-hydroxy pregnenolone.

A novel cytochrome P450 expressed primarily in brain

hct-1 (hippocampal transcript) was detected in a differential screen of a rat hippocampal cDNA library. Expression of hct-1 was enriched in the formation but was also detected in rat liver and kidney, though at much lower levels; expression was barely detectable in testis, ovary, and adrenal. In liver, unlike brain, expression was sexually dimorphic; hepatic expression was greatly reduced in female rats. In mouse, brain expression was widespread, with the highest levels being detected in corpus callosum; only low levels were detected in liver. Sequence analysis of rat and mouse hct-1 cDNAs revealed extensive homologies with cytochrome P450s (CYPs), a diverse family of heme-binding monooxygenases that metabolize a range of substrates including steroids, fatty acids, and xenobiotics. Among the CYPs, hct-1 is most similar (39% at the amino acid sequence) to cholesterol 7 alpha-hydroxylase (CYP7) and contains a postulated steroidogenic domain present in other steroid-metabolizing CYPs but clearly represents a type of CYP not previously reported. Genomic Southern analysis suggests that a single gene corresponding to hct-1 is present in mouse, rat, and human. hct-1 is unusual in that, unlike all other CYPs described, the primary site of expression is in the brain. Similarity to CYP7 and other steroid-metabolizing CYPs may argue that hct-1 (CYP7B) plays a role in steroid metabolism in brain, notable because of the documented ability of brain-derived steroids (neurosteroids) to modulate cognitive function in vivo.

Transcriptional regulation of cell invasion: AP-1 regulation of a multigenic invasion programme

The focus of this review will be on the regulation of the multigenic invasion programme by activator protein-1 (AP-1). Investigation of AP-1-regulated gene expression in transformed cells can be used to identify the genes in the multigenic invasion programme and to validate them as targets for diagnosis or therapy.

Neurosteroid hydroxylase CYP7B: vivid reporter activity in dentate gyrus of gene-targeted mice and abolition of a widespread pathway of steroid and oxysterol hydroxylation

The major adrenal steroid dehydroepiandrosterone (DHEA) enhances memory and immune function but has no known dedicated receptor; local metabolism may govern its activity. We described a cytochrome P450 expressed in brain and other tissues, CYP7B, that catalyzes the 7alpha-hydroxylation of oxysterols and 3beta-hydroxysteroids including DHEA. We report here that CYP7B mRNA and 7alpha-hydroxylation activity are widespread in rat tissues. However, steroids related to DHEA are reported to be modified at positions other than 7alpha, exemplified by prominent 6alpha-hydroxylation of 5alpha-androstane-3beta,17beta-diol (A/anediol) in some rodent tissues including brain. To determine whether CYP7B is responsible for these and other activities we disrupted the mouse Cyp7b gene by targeted insertion of an IRES-lacZ reporter cassette, placing reporter enzyme activity (beta-galactosidase) under Cyp7b promoter control. In heterozygous mouse brain, chromogenic detection of reporter activity was strikingly restricted to the dentate gyrus. Staining did not exactly reproduce the in situ hybridization expression pattern; post-transcriptional control is inferred. Lower level staining was detected in cerebellum, liver, and kidney, and which largely paralleled mRNA distribution. Liver and kidney expression was sexually dimorphic. Mice homozygous for the insertion are viable and superficially normal, but ex vivo metabolism of DHEA to 7alpha-hydroxy-DHEA was abolished in brain, spleen, thymus, heart, lung, prostate, uterus, and mammary gland; lower abundance metabolites were also eliminated. 7alpha-Hydroxylation of 25-hydroxycholesterol and related substrates was also abolished, as was presumed 6alpha-hydroxylation of A/anediol. These different enzyme activities therefore derive from the Cyp7b gene. CYP7B is thus a major extrahepatic steroid and oxysterol hydroxylase and provides the predominant route for local metabolism of DHEA and related molecules in brain and other tissues.

Regulation of a multigenic invasion programme by the transcription factor, AP-1: re-expression of a down-regulated gene, TSC-36, inhibits invasion

The transcription factor AP-1 (activator protein-1) is required for transformation by many oncogenes, which function upstream of it in the growth factor-ras signal transduction pathway. Previously, we proposed that one role of AP-1 in transformation is to regulate the expression of a multigenic invasion programme. As a test of this proposal we sought to identify AP-1 regulated genes based upon their differential expression in 208F rat fibroblasts transformed by FBR-v-fos (FBR), and to determine if they functioned in the invasion programme. Subtracted cDNA libraries specific for up- or down-regulated genes in FBRs compared to 208Fs were constructed and analysed. Northern analysis revealed that the cDNAs in both libraries represented differentially expressed genes. Nucleic acid sequence analysis of randomly selected cDNA clones from each library coupled with searches of nucleic acid and amino acid sequence databases determined that many of the cDNAs represented proteins that function in various aspects of the invasion process. Functional analysis of one the down-regulated genes, TSC-36/follistatin-related protein (TSC-36/Frp), which has not previously been associated with invasion, demonstrated that its expression in FBRs inhibited in vitro invasion. These results support the proposal that AP-1 in transformed cells regulates a multigenic invasion programme.

Peritoneal macrophage and blood monocyte functions after open and laparoscopic-assisted cecectomy in rats

BACKGROUND

It has been well established that open abdominal surgery results in systemic immunosuppression postoperatively; in contrast, laparoscopic surgery is associated with significantly better preserved systemic immune function. However, when intraperitoneal (local) immune function is considered, laparoscopic procedures done under a CO2 pneumoperitoneum (pneumo) have been shown to result in greater immunosuppression compared to that of open surgery. Few studies have simultaneously assessed systemic and local immune function. The purpose of this study was to assess peripheral blood mononuclear cell (PBMC) and peritoneal macrophage tumor necrosis factor-alpha (TNF-alpha) levels, H2O2 production, and MHC class II antigen expression after open and laparoscopically assisted cecectomy in a rat model.

METHODS

A total of 75 Sprague Dawley rats were used for three separate experiments. For each study, rats were randomly divided into three groups: anesthesia alone (AC), laparoscopic-assisted cecectomy (LC), and open cecectomy via full laparotomy (OP). A CO2 pneumo was used for laparoscopic operations. On postoperative day 1 the animals were sacrificed, macrophages were harvested via intraperitoneal lavage, and PBMCs were isolated from whole blood obtained by cardiac puncture. In experiment 1, macrophages and PBMC from each animal were stimulated with lipopolysaccharide, after which TNF-alpha levels of the supernatant were determined. In experiment 2, after stimulation with PMA, H2O2 release was assessed by measuring fluorescence. In experiment 3, via flow cytometry, the number of cells with surface MHC class II proteins were determined. Data from the three groups in each experiment were compared using analysis of variance Tukey-Kramer tests.

RESULTS

Macrophages and PBMC from rats in the OP group released significantly more TNF-alpha than cells from rats in the LC ( p < 0.05) or AC ( p < 0.05) groups. Macrophages from rats in the OP group released significantly less H2O2 than cells from the AC ( p < 0.01) and LC ( p < 0.05) groups. There was no difference between the AC and LC results. No significant differences in PBMC H2O2 release were noted among any of the groups. OP group macrophages expressed significantly less MHC class II antigen than did AC group macrophages ( p < 0.05). No differences were noted among the LC results and either the OP or AC group's outcomes. No differences were noted in PBMC MHC class II expression among any of the groups.

CONCLUSIONS

In all instances, the LC group's macrophage results were similar to the AC group's results. OC group macrophages produced significantly more TNF-alpha and less H2O2 than both the AC and LC groups. MHC class II protein expression was less for the OC group than for the AC group. OC group PBMCs produced more TNF-alpha. No differences in PBMC H2O2 release or MHC class II expression were noted. Laparoscopic methods better preserves the baseline values of the parameters studied.

Hybrid laparoscopic flexure takedown and open procedure for rectal resection is associated with significantly shorter length of stay than equivalent open resection

PURPOSE

Laparoscopic-assisted, sphincter-saving resection (largest incision < 7 cm) of the middle and distal rectum is technically very difficult and, with regard to cancers, has not been demonstrated to be oncologically safe. The hypothesis of this retrospective study is that a hybrid operation that combines laparoscopic and open methods would be associated with short-term outcome benefits compared with open surgery results for patients undergoing sphincter-saving proctectomy.

METHODS

A total of 31 hybrid and 25 fully open rectal resection patients were compared in this retrospective review. All patients had splenic flexure takedown and rectal anastomosis. The hybrid approach consisted of laparoscopic splenic flexure takedown (with or without partial rectal mobilization and devascularization) followed by completion of the procedure via infraumbilical midline laparotomy. The indication was neoplasm in 87 percent of hybrid patients and in 68 percent of open patients. The majority of tumors were located between 4 and 10 cm from the dentate line.

RESULTS

Fifty-eight percent of hybrid and 68 percent of open patients had low anterior or coloanal resections, and 48 percent of hybrid and 64 percent of open patients underwent temporary diversion via ileostomy. The mean hybrid midline incision length was 11 cm compared with 24 cm for open patients (P < 0.0001). The neoplastic specimens were similar with regard to margins and lymph node harvest. Similar complication rates were noted in both groups. Nonsignificant benefits for hybrid patients (0.9-1.2 days) were seen with regard to length of time until toleration of liquid or solid diet and first flatus. Hybrid patients experienced their first bowel movements 4.1 days vs. 5.7 days for the open group (P = 0.03). Mean length of stay was significantly shorter for hybrid patients (6.1. days) than for open patients (11.1 days; P = 0.0006).

CONCLUSION

This preliminary retrospective study suggests that a combined hybrid laparoscopic and open approach to sphincter-saving proctectomy permits a similar resection as open methods and may be associated with a length-of-stay benefit and more rapid return of bowel function. Prospective studies will be needed before any firm conclusions can be drawn.

Cell type-specific interactions of transcription factors with a housekeeping promoter in vivo

Mammalian housekeeping promoters represent a class of regulatory elements different from those of tissues-specific genes, lacking a TATA box and associated with CG-rich DNA. We have compared the organization of the housekeeping Htf9 promoter in different cell types by genomic footprinting. The sites of in vivo occupancy clearly reflected local combinations of tissue-specific and ubiquitous binding factors. The flexibility of the Htf9 promoter in acting as the target of cell-specific combinations of factors may ensure ubiquitous expression of the Htf9-associated genes.

Persistent central diabetes insipidus presenting in a very low birth weight infant successfully managed with intranasal dDAVP

We report a case of a premature very low birth weight infant who presented shortly after birth with idiopathic central diabetes insipidus that persisted beyond the neonatal period and has been successfully managed with intranasal 1-desamino-8-D-arginine vasopressin. Although this condition is rare in neonates, early recognition, evaluation, and therapy may prevent more severe morbidity. Long-term successful management resulting in normal growth and development during infancy can be achieved with intranasal 1-desamino-8-D-arginine vasopressin therapy.

Phosphorylation of protein kinase C-related kinase PRK2 during meiotic maturation of starfish oocytes

The resumption of meiosis in the developing starfish oocyte is the result of intracellular signaling events initiated by 1-methyladenine stimulation. One of the earliest detectable kinase activities during meiotic maturation of starfish oocytes is a protein kinase C or PKC-like activity. In this study, several isoforms of protein kinase C were cloned from the oocyte; however, the most abundant PKC-like maternal transcript corresponds to protein kinase C-related kinase 2 (PRK2). PRK2 is expressed in the immature oocyte and at least until germinal vesicle breakdown. Subcellular localization of PRK2 revealed a cytoplasmic distribution in the immature oocyte, which, during meiotic maturation, remained in the cytoplasm but also localized to the disintegrating germinal vesicle. Significantly, PRK2 is phosphorylated in vivo in response to 1-methyladenine which precedes MPF activation, making PRK2 a candidate regulator of early signaling events of meiotic maturation.

Increased platelet-derived growth factor (PDGF) release after laparotomy stimulates systemic tumor growth in mice

BACKGROUND

Our laboratory has demonstrated that tumors grow larger and are more easily established following laparotomy than after carbon dioxide (CO2) pneumoperitoneum or anesthesia alone. We have also shown that tumor cells incubated with serum from laparotomized mice proliferated significantly faster in vitro than those incubated with plasma from mice that underwent laparoscopy or anesthesia alone. We hypothesized that differing levels of a plasma-soluble growth factor(s) postoperatively causes tumors to proliferate faster after laparotomy. This study's purpose was to isolate and characterize the plasma growth factor(s) responsible for the increased growth of systemic tumors after laparotomy.

METHODS

Female Balb/C mice (n = 100) were randomized to two groups: anesthesia control (AC) or midline sham laparotomy (4 cm) (Open). Plasma was collected on Postoperative day 4. For the tumor proliferation assay, C-26 colon cancer cells were incubated in media with either 10% AC or Open "raw" plasma (not passed through column), or AC or Open plasma that had been passed through the column. For elution of heparin-binding proteins, plasma from each group was passed through a heparin-sepharose column. Elution of bound proteins was accomplished with a 0.1-2 M NaCl gradient. Each fraction was examined for protein content. For the anti-platelet-derived growth factor (PDGF) neutralizing antibody study, C-26 cells were incubated with one of four plasma preparations: AC or Open plasma alone, or AC or Open plasma incubated with anti-PDGF antibody. For both studies, tumor proliferation was determined after 2 days with an MTS/PMS assay. Results from each group were compared and differences determined using analysis of variance (ANOVA) and Tukey-Kramer tests.

RESULTS

On heparin chromatography, a single elution peak consistent with PDGF was present in both AC and Open plasma and was 1.5 times greater in the Open plasma. The first tumor proliferation assay showed that tumor cells incubated with Open plasma proliferated 2.5 times faster than those with AC plasma (p < 0.0001). Passage of AC plasma through the column did not alter its mitogenic activity, but Open plasma thus treated demonstrated significantly decreased mitogenic activity. The second tumor proliferation assay showed that anti-PDGF antibody had no effect on the mitogenic activity of the AC plasma but decreased the mitogenic activity of the Open plasma to the AC plasma level.

CONCLUSIONS

Laparotomy is associated with higher levels of a heparin-binding plasma factor, consistent with PDGF. The enhanced mitogenic activity of the OP plasma was neutralized with anti-PDGF antibody. Increased plasma levels of PDGF after laparotomy may be responsible for accelerated tumor growth following laparotomy in mice.

Protein kinase C-related kinase 2 phosphorylates the protein synthesis initiation factor eIF4E in starfish oocytes

Phosphorylation of eIF4E is required for protein synthesis during starfish oocyte maturation. The activity of protein kinase C-related kinase 2 (PRK2) increases prior to the phosphorylation of eIF4E (G. Stapleton et al., 1998, Dev. Biol. 193, 34-46). We investigate here whether eIF4E is activated by PRK2. A 3.5-kb eIF4E clone isolated from starfish cDNA is 57% identical to human eIF4E and contains the putative phosphorylation site serine-209. The serine-209 environment (SKTGS(209)MAKSRF) is similar to the consensus sequence of the phosphorylation site of protein kinase C and related kinases. A starfish eIF4E fusion protein (GST-4E) was phosphorylated in vitro by PRK2 in the presence of 1,2-diolyl-sn-glycerol 3-phosphate. In contrast, replacing the GST-4E serine-209 with an alanine significantly reduced this phosphorylation. Analysis by two-dimensional phosphopeptide mapping reveals a major phosphopeptide in trypsin-digested GST-4E, but not in its serine-209 mutant. Importantly, this major phosphopeptide in GST-4E corresponds to a major phosphopeptide of eIF4E isolated from (32)P-labeled oocytes. Thus, PRK2 may regulate translation initiation during oocyte maturation by phosphorylating the serine-209 residue of eIF4E in starfish. We also demonstrate that high levels of cAMP inhibit the activation of PRK2, eIF4E, and the eIF4E binding protein during starfish oocyte maturation, while PI3 kinase activates these proteins.

Human Salmonellosis Outbreak Linked to Salmonella Typhimurium Epidemic in Wild Songbirds, United States, 2020-2021

Salmonella infection causes epidemic death in wild songbirds, with potential to spread to humans. In February 2021, public health officials in Oregon and Washington, USA, isolated a strain of Salmonella enterica serovar Typhimurium from humans and a wild songbird. Investigation by public health partners ultimately identified 30 illnesses in 12 states linked to an epidemic of Salmonella Typhimurium in songbirds. We report a multistate outbreak of human salmonellosis associated with songbirds, resulting from direct handling of sick and dead birds or indirect contact with contaminated birdfeeders. Companion animals might have contributed to the spread of Salmonella between songbirds and patients; the outbreak strain was detected in 1 ill dog, and a cat became ill after contact with a wild bird. This outbreak highlights a One Health issue where actions like regular cleaning of birdfeeders might reduce the health risk to wildlife, companion animals, and humans.

Canine vector-borne disease in domestic dogs on Isla Santa Cruz, Galápagos

Vector-borne diseases result in significant morbidity and mortality in domestic dogs in tropical and subtropical regions and also pose a potential threat to wildlife species and humans. Ehrlichia canis, the causative agent of canine monocytic ehrlichiosis (CME), has a high reported seroprevalence in dogs on Santa Cruz in the Galápagos Islands, Ecuador. Veterinary diagnostic and treatment resources are often scarce and clinical follow-up is lacking in the Galápagos. This study evaluated 58 dogs presenting to the Darwin Animal Doctors clinic in the city of Puerto Ayora on Santa Cruz Island during August of 2018. The seroprevalence of E. canis/Ehrlichia ewingii (48.3%), Anaplasma phagocytophilum/Anaplasma platys (12.1%), and Borrelia burgdorferi (0%), as well as the proportion of dogs actively infected with E. canis (12.1%) and E. ewingii (0%), are reported. Active infection was defined as the identification of antigen by PCR. Dogs with a packed cell volume (PCV) ≤ 30% had a 10-fold risk of active infection with E. canis compared to dogs with a PCV ≥ 31% (p = .0124). A PCV cutoff of 30% may be a useful screening tool for active E. canis infection in regions with high Ehrlichia seroprevalence, in the absence of other apparent causes of anemia. Dirofilaria immitis antigen was present in 6.9% of examined dogs, with the highest prevalence in the barrio Las Ninfas. PCR and Sanger sequencing were used to provide the first molecular identification of D. immitis in the Galápagos. This study updates the seropositivity and prevalence data of these canine vector-borne pathogens and highlights the need for continued surveillance in the region.

Multistate outbreak of Salmonella Typhimurium linked to pet hedgehogs, United States, 2018-2019

In December 2018, PulseNet, the national laboratory network for enteric disease surveillance, identified an increase in Salmonella Typhimurium isolates with an uncommon pulsed-field gel electrophoresis pattern which was previously isolated from hedgehogs. CDC, state, and local health partners interviewed patients with a questionnaire that focused on hedgehog exposures, conducted traceback of patients' hedgehog purchases, and collected hedgehog faecal pellets and environmental samples. Isolates in this outbreak were analysed using core-genome multi-locus sequence typing (cgMLST) and compared to sequence data from historic clinical isolates from a 2011-2013 outbreak of Salmonella Typhimurium illnesses linked to pet hedgehogs. Fifty-four illnesses in 23 states were identified between October 2018 and September 2019. Patients ranged from <1 to 95 years, and 65% were female. Eight patients were hospitalized. Eighty-one per cent (29/36) of patients interviewed reported contact with a hedgehog before becoming ill; of these, 21 (72%) reported owning a hedgehog. Analysis of 53 clinical, 11 hedgehog, and two hedgehog bedding isolates from this outbreak, seven hedgehog isolates obtained prior to this outbreak, and two clinical isolates from the 2011-2013 outbreak fell into three distinct groupings (37 isolates in Clade 1 [0-10 alleles], 28 isolates in Clade 2 [0-7 alleles], and eight isolates in Clade 3 [0-12 alleles]) and were collectively related within 0-31 alleles by cgMLST. Purchase information available from 20 patients showed hedgehogs were purchased from multiple breeders across nine states, a pet store, and through an online social media website; a single source of hedgehogs was not identified. This outbreak highlights the ability of genetic sequencing analysis to link historic and ongoing Salmonella illness outbreaks and demonstrates the strain of Salmonella linked to hedgehogs might continue to be a health risk to hedgehog owners unless measures are taken to prevent transmission.

Antimicrobial resistance in multistate outbreaks of nontyphoidal Salmonella infections linked to animal contact-United States, 2015-2018

Animal contact is an established risk factor for nontyphoidal Salmonella infections and outbreaks. During 2015-2018, the U.S. Centers for Disease Control and Prevention (CDC) and other U.S. public health laboratories began implementing whole-genome sequencing (WGS) of Salmonella isolates. WGS was used to supplement the traditional methods of pulsed-field gel electrophoresis for isolate subtyping, outbreak detection, and antimicrobial susceptibility testing (AST) for the detection of resistance. We characterized the epidemiology and antimicrobial resistance (AMR) of multistate salmonellosis outbreaks linked to animal contact during this time period. An isolate was considered resistant if AST yielded a resistant (or intermediate, for ciprofloxacin) interpretation to any antimicrobial tested by the CDC or if WGS showed a resistance determinant in its genome for one of these agents. We identified 31 outbreaks linked to contact with poultry (n = 23), reptiles (n = 6), dairy calves (n = 1), and guinea pigs (n = 1). Of the 26 outbreaks with resistance data available, we identified antimicrobial resistance in at least one isolate from 20 outbreaks (77%). Of 1,309 isolates with resistance information, 247 (19%) were resistant to ≥1 antimicrobial, and 134 (10%) were multidrug-resistant to antimicrobials from ≥3 antimicrobial classes. The use of resistance data predicted from WGS increased the number of isolates with resistance information available fivefold compared with AST, and 28 of 43 total resistance patterns were identified exclusively by WGS; concordance was high (>99%) for resistance determined by AST and WGS. The use of predicted resistance from WGS enhanced the characterization of the resistance profiles of outbreaks linked to animal contact by providing resistance information for more isolates.

Assessing the difference in contamination of retail meat with multidrug-resistant bacteria using for-consumer package label claims that indicate on-farm antibiotic use practices- United States, 2016-2019

BACKGROUND

Antibiotic use in food-producing animals can select for antibiotic resistance in bacteria that can be transmitted to people through contamination of food products during meat processing. Contamination resulting in foodborne illness contributes to adverse health outcomes. Some livestock producers have implemented antibiotic use reduction strategies marketed to consumers on regulated retail meat packaging labels ("label claims").

OBJECTIVE

We investigated whether retail meat label claims were associated with isolation of multidrug-resistant organisms (MDROs, resistant to ≥3 classes of antibiotics) from U.S. meat samples.

METHODS

We utilized retail meat data from the U.S. Food and Drug Administration National Antimicrobial Resistance Monitoring System (NARMS) collected during 2016-2019 for bacterial contamination of chicken breast, ground turkey, ground beef, and pork chops. We used modified Poisson regression models to compare the prevalence of MDRO contamination among meat samples with any antibiotic restriction label claims versus those without such claims (i.e., conventionally produced).

RESULTS

In NARMS, 62,338 meat samples were evaluated for bacterial growth from 2016-2019. Of these, 24,446 (39%) samples had label claims that indicated antibiotic use was restricted during animal production. MDROs were isolated from 2252 (4%) meat samples, of which 71% (n = 1591) were conventionally produced, and 29% (n = 661) had antibiotic restriction label claims. Compared with conventional samples, meat with antibiotic restriction label claims had a statistically lower prevalence of MDROs (adjusted prevalence ratio: 0.66; 95% CI: 0.61, 0.73). This relationship was consistent for the outcome of any bacterial growth.

IMPACT

This repeated cross-sectional analysis of a nationally representative retail meat surveillance database in the United States supports that retail meats labeled with antibiotic restriction claims were less likely to be contaminated with MDROs compared with retail meat without such claims during 2016-2019. These findings indicate the potential for the public to become exposed to bacterial pathogens via retail meat and emphasizes a possibility that consumers could reduce their exposure to environmental reservoirs of foodborne pathogens that are resistant to antibiotics.

Salmonella Vitkin Outbreak Associated with Bearded Dragons, Canada and United States, 2020-2022

We identified 2 cases of Salmonella enterica serovar Vitkin infection linked by whole-genome sequencing in infants in Ontario, Canada, during 2022. Both households of the infants reported having bearded dragons as pets. The outbreak strain was also isolated from an environmental sample collected from a patient's bearded dragon enclosure. Twelve cases were detected in the United States, and onset dates occurred during March 2021-September 2022 (isolates related to isolates from Canada within 0-9 allele differences by core-genome multilocus sequence typing). Most US patients (66.7%) were <1 year of age, and most (72.7%) had reported bearded dragon exposure. Hospitalization was reported for 5 (38.5%) of 13 patients. Traceback of bearded dragons identified at least 1 potential common supplier in Southeast Asia. Sharing rare serovar information and whole-genome sequencing data between Canada and the United States can assist in timely identification of outbreaks, including those that might not be detected through routine surveillance.

Distance and destination of retail meat alter multidrug resistant contamination in the United States food system

Antibiotic-resistant infections are a global concern, especially those caused by multidrug-resistant (MDR) bacteria, defined as those resistant to more than three drug classes. The animal agriculture industry contributes to the antimicrobial resistant foodborne illness burden via contaminated retail meat. In the United States, retail meat is shipped across the country. Therefore, understanding geospatial factors that influence MDR bacterial contamination is vital to protect consumers and inform interventions. Using data available from the United States Food and Drug Administration's National Antimicrobial Resistance Monitoring System (NARMS), we describe retail meat shipping distances using processor and retailer locations and investigated this distance as a risk factor for MDR bacteria meat contamination using log-binomial regression. Meat samples collected during 2012-2014 totaled 11,243, of which 4791 (42.61%) were contaminated with bacteria and 835 (17.43%) of those bacteria were MDR. All examined geospatial factors were associated with MDR bacteria meat contamination. After adjustment for year and meat type, we found higher prevalence of MDR contamination among meat processed in the south (relative adjusted prevalence ratio [aPR] 1.35; 95% CI 1.06-1.73 when compared to the next-highest region), sold in Maryland (aPR 1.12; 95% CI 0.95-1.32 when compared to the next-highest state), and shipped from 194 to 469 miles (aPR 1.59; 95% CI 1.31-1.94 when compared to meats that traveled < 194 miles). However, sensitivity analyses revealed that New York sold the meat with the highest prevalence of MDR Salmonella contamination (4.84%). In this secondary analysis of NARMS data, both geographic location where products were sold and the shipping distance were associated with microbial contamination on retail meat.