SlipO2Chip - single-cell respiration under tuneable environments.

In disciplines like toxicology and pharmacology, oxygen (O2) respiration is a universal metric for evaluating the effects of chemicals across various model systems, including mammalian and microalgal cells. However, for these cells the common practice is to segregate populations into control and exposure groups, which assumes direct equivalence in their responses and does not take into account heterogeneity among individual cells. This lack of resolution impedes our ability to precisely investigate differences among experimental groups with small or limited sample sizes. To overcome this barrier, we introduce SlipO2Chip, an innovative glass microfluidic platform for precisely quantifying single-cell O2 respiration in the coordinated absence and presence of chemical solutes. SlipO2Chip comprises a wet-etched fused silica channel plate on the top and a dry-etched borosilicate microwell plate at the bottom. The microwells are coated with Pt(II) meso-tetra(pentafluorophenyl)porphine (PtTFPP), an O2 sensing optode material and an O2-independent reference dye. A custom 3D-printed holder facilitates the controlled horizontal movement ('slipping') of the channel plate over the microwell plate, thereby establishing or disrupting the fluid path over microwells. Collectively, these design elements enable the immobilization of single-cells in microwells, their exposure to controlled fluid flows, the coordinated opening and closing of microwells and repeated measurements of single-cell O2 respiration. Uniquely, by sequentially executing opening and closing it becomes possible to measure single-cell respiration prior to and after exposure to chemical solutes. In a proof-of-concept application, we utilized SlipO2Chip to measure the impact of increasing exposures of the marine bacterial signal 2-heptyl-4-quinolone (HHQ) on the dark respiration of the diatom Ditylum brightwellii at single-cell resolution. Results revealed a concentration-dependent decrease in per-cell O2 dark respiration, with a maximum reduction of 40.2% observed at HHQ concentrations exceeding 35.5 µM, and a half-maximal effective concentration (EC50) of 5.8 µM, consistent with that obtained via conventional bulk respiration methods. The ability of SlipO2Chip to sequentially assess the effects of chemical substances on single-cell O2 metabolism is advantageous for research where sample volumes are limited, such as clinical biopsies, studies involving rare microbial isolates, and toxicological studies aiming to address exposure effects while accounting for cell-to-cell variability.

Readability of Online Spanish Materials for Breast Reconstruction Using Deep Inferior Epigastric Perforator Flaps.

Background The internet has become an increasingly popular tool for patients to find information pertaining to medical procedures. Although the information is easily accessible, data shows that many online educational materials pertaining to surgical subspecialties are far above the average reading level in the United States. The aim of this study was to evaluate the English and Spanish online materials for the deep inferior epigastric perforator (DIEP) flap reconstruction procedure. Methods The first eight institutional or organizational websites that provided information on the DIEP procedure in English and Spanish were included. Each website was evaluated using the Patient Education and Materials Assessment Tool (PEMAT), Cultural Sensitivity Assessment Tool (CSAT), and either Simplified Measure of Gobbledygook (SMOG) for English websites or Spanish Orthographic Length (SOL) for Spanish websites. Results The English websites had a statistically lower CSAT score compared to the Spanish websites (p=0.006). However, Spanish websites had a statistically higher percentage of complex words compared to English sources (p<0.001). An analysis of reading grade levels through SMOG and SOL scores revealed that Spanish websites had statistically lower scores (p<0.001). There were no statistically significant differences in the understandability or actionability scores between the English and Spanish websites. Conclusions Online educational materials on the DIEP flap reconstruction procedure should be readable, understandable, actionable, and culturally sensitive. Our analysis revealed that improvements can be made in understandability and actionability on these websites. Plastic surgeons should be aware of what constitutes a great online educational resource and what online educational materials their patients will have access to.

Novel Treatment of Pyoderma Gangrenosum With Porcine-Derived Extracellular Matrix Following Bilateral Latissimus Dorsi Breast Reconstruction: A Case Report.

Pyoderma gangrenosum (PG) is a rare disease characterized by ulcerative cutaneous lesions that can occur postoperatively and is often associated with autoimmune disorders. PG is diagnosed by excluding other conditions that can cause ulcerations, such as infections, which may also result in immunosuppressive treatment delays and suboptimal wound care. Operative debridement of wounds has traditionally been avoided in the acute setting secondary to pathergy. This article presents a case of extensive breast PG that was successfully treated with surgical debridement, porcine-derived extracellular matrix, and negative pressure wound therapy while on systemic immunosuppressive therapy.

Utilization of Topical Polysporin and Triamcinolone for the Treatment of Hypergranulation Tissue.

Hypergranulation is the abnormal accumulation of granulation tissue in a wound and is commonly seen in burns. It impairs wound healing and can predispose patients to infection. There is no gold standard treatment for hypergranulation tissue, but some options include surgical debridement, chemical cautery with silver nitrate, and topical steroids. Silver nitrate treatment is painful and can lead to scarring, so topical steroid use is on the rise. A retrospective review, between January 1, 2017 and August 30, 2021, at a tertiary burn center was performed to analyze outcomes of hypergranulation tissue after treatment with a topical 50/50 mixture of triamcinolone (Perrigo, Dublin, Ireland) and Polysporin (Johnson & Johnson, New Brunswick, NJ). One hundred and sixteen patients were treated with triamcinolone and Polysporin for hypergranulation tissue, although 24 did not meet inclusion criteria. Eighty-eight out of 92 patients were successfully treated until hypergranulation resolution, while 4/92(4.3%) required silver nitrate or surgery despite the topical cream to achieve resolution. In the 88 patients successfully treated until hypergranulation resolution, 99 areas of hypergranulation were treated. Forty-one of 99 (41.4%) hypergranulation areas resolved within 2 weeks. The average time to hypergranulation resolution was 27.5 ± 2.5 days. We found that a novel 50/50 mixture of triamcinolone and Polysporin topical ointment is an effective and safe treatment for hypergranulation tissue in burn wounds. Further prospective studies are needed to determine its efficacy and safety profile.

Breastfeeding Ability After Breast Reductions: What does the Literature Tell us in 2023?

INTRODUCTION: Reduction mammaplasties are routinely performed on women of child-bearing age, yet there still exists some uncertainty regarding a patient's ability to breastfeed following the procedure. This is due to inconsistent definitions of "successful" breastfeeding, a variety of pedicles implemented, and inadequate follow-up in the published literature. Our aim was to summarize the current data and provide clear recommendations for counseling patients on expected breastfeeding outcomes following reduction mammaplasty. METHODS: A systematic review and meta-analysis in accordance with the PRISMA guidelines was conducted. We included papers that reported proportion of breastfeeding ability following reduction mammaplasty. RESULTS: We identified 33 papers that met our inclusion criteria. We found that women who undergo reduction mammaplasty are at a 3.5 times increased odds of not being able to breastfeed compared to controls. Overall, reduction mammaplasty patients have a breastfeeding success rate of 62%. The breastfeeding success rate for patients with inferior pedicles was 64%, superior pedicles was 59%, and lateral pedicles was 55%. No conclusions could be drawn regarding medial, central, vertical, and horizontal pedicles on breastfeeding ability. CONCLUSION: Current data suggest that women undergoing reduction mammaplasty have an increased odds of unsuccessful breastfeeding when compared to similar women who have not undergone the procedure. Based on the current literature, pedicle type does play a role in rate of breastfeeding success, although there is a need for further research on the aforementioned pedicles. Physicians should be aware of the likelihood of successful breastfeeding following reduction mammaplasty so that patients can be more thoroughly counseled prior to a decision for surgery. LEVEL OF EVIDENCE I: This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .

A bacterial quorum sensing signal is a potent inhibitor of de novo pyrimidine biosynthesis in the globally abundant Emiliania huxleyi.

Interactions between marine phytoplankton, viruses, and bacteria drive biogeochemical cycling, shape marine trophic structures, and impact global climate. Microbially produced compounds have emerged as key players in influencing eukaryotic organismal physiology, and in turn, remodel microbial community structure. This work aimed to reveal the molecular mechanism by which the bacterial quorum sensing molecule 2-heptyl-4-quinolone (HHQ), produced by the marine gammaproteobacterium Pseudoalteromonas spp., arrests cell division and confers protection from virus-induced mortality in the bloom-forming coccolithophore Emiliania huxleyi. Previous work has established alkylquinolones as inhibitors of dihydroorotate dehydrogenase (DHODH), a fundamental enzyme catalyzing the fourth step in pyrimidine biosynthesis and a potential antiviral drug target. An N-terminally truncated version of E. huxleyi DHODH was heterologously expressed in E. coli, purified, and kinetically characterized. Here, we show HHQ is a potent inhibitor (Ki of 2.3 nM) of E. huxleyi DHODH. E. huxleyi cells exposed to brequinar, the canonical human DHODH inhibitor, experienced immediate, yet reversible cellular arrest, an effect which mirrors HHQ-induced cellular stasis previously observed. However, brequinar treatment lacked other notable effects observed in HHQ-exposed E. huxleyi including significant changes in cell size, chlorophyll fluorescence, and protection from virus-induced lysis, indicating HHQ has additional as yet undiscovered physiological targets. Together, these results suggest a novel and intricate role of bacterial quorum sensing molecules in tripartite interdomain interactions in marine ecosystems, opening new avenues for exploring the role of microbial chemical signaling in algal bloom regulation and host-pathogen dynamics.

A marine-derived fatty acid targets the cell membrane of Gram-positive bacteria.

IMPORTANCE: With the lack of new antibiotics in the drug discovery pipeline, coupled with accelerated evolution of antibiotic resistance, new sources of antibiotics that target pathogens of clinical importance are paramount. Here, we use bacterial cytological profiling to identify the mechanism of action of the monounsaturated fatty acid (Z)-13-methyltetra-4-decenoic acid isolated from the marine bacterium Olleya marilimosa with antibacterial effects against Gram-positive bacteria. The fatty acid antibiotic was found to rapidly destabilize the cell membrane by pore formation and membrane aggregation in Bacillus subtilis, suggesting that this fatty acid may be a promising adjuvant used in combination to enhance antibiotic sensitivity.

A Novel Method to Determine Patient Skin Type: The Skin Analyzer.

Measuring skin color for medical research in an objective and nonbiased manner usually requires expensive equipment such as spectrophotometry and requires the subject to be present in person. We present a novel method to measure skin color from photographs using the Skin Analyzer application as a more effective, accessible, and efficient alternative. A desktop application, the Skin Analyzer, was developed to convert skin samples collected from digital images to the L*a*b color space and uses those values to calculate an individual typology angle that correlates to a Fitzpatrick skin type. To assess accuracy in variable lighting, six known colors representing the six Fitzpatrick skin types were printed and photographed in 15 separate locations within the hospital. To account for user variability in sample selection, interrater reliability was calculated with data generated by 13 untrained users testing the app on six subjects. The accuracy of measuring known values, which is the classification accuracy, was calculated to be 80%. Krippendorff alpha test was used to evaluate interrater reliability. The obtained alpha of 0.84 indicates a high interrater reliability. The high accuracy and reliability make the Skin Analyzer a suitable method of objectively determining Fitzpatrick skin type from images. The app may be used to investigate the effects of skin tone in various areas of interest, especially in retrospective studies where skin colorimeters cannot be used.

Reverse Abdominoplasty for Mastectomy Defect Closure in Advanced Breast Cancer.

BACKGROUND: Breast cancer patients with locally advanced breast cancer who require radical mastectomy are left with large chest wall defects. This poses a significant reconstructive challenge as many high-risk patients require timely postmastectomy adjuvant therapy. While the reverse abdominoplasty technique is commonly used for aesthetic improvement of the anterior trunk, it can be also be effectively used for closure of extensive mastectomy defects in this patient population. METHODS: We conducted a retrospective cohort study of all consecutive patients who underwent an extensive radical mastectomy followed by immediate closure with the reverse abdominoplasty technique at a single tertiary cancer center from June 2017 to July 2022. Patients who had concurrent skin grafting or breast mound flap reconstruction were excluded. Demographic, medical, oncologic, and reconstructive data were collected. RESULTS: Six patients were treated with reverse abdominoplasty for 9 chest wall defects after surgical excision of locally advanced breast cancer. The median tumor size was 10.7 cm (range, 6.7-10 cm) and the median mastectomy weight was 865.7 g (range, 356.4-1247.7 g). On average, the operation length was 191 minutes (range, 86-257 minutes) and the postoperative length of stay was 2.2 days (range, 1-5 days). All patients underwent systemic adjuvant therapy and the median time from surgery to initiation of therapy was 44.5 days (range, 32-75 days). CONCLUSIONS: Reverse abdominoplasty is a simple and safe technique to reliably close large defects after locally advanced breast cancer excision. It has a short operative time, hospital stay, and turnaround time to initiation of adjuvant therapy.

Bacterial Quorum-Sensing Signal Arrests Phytoplankton Cell Division and Impacts Virus-Induced Mortality.

Interactions between phytoplankton and heterotrophic bacteria fundamentally shape marine ecosystems by controlling primary production, structuring marine food webs, mediating carbon export, and influencing global climate. Phytoplankton-bacterium interactions are facilitated by secreted compounds; however, linking these chemical signals, their mechanisms of action, and their resultant ecological consequences remains a fundamental challenge. The bacterial quorum-sensing signal 2-heptyl-4-quinolone (HHQ) induces immediate, yet reversible, cellular stasis (no cell division or mortality) in the coccolithophore Emiliania huxleyi; however, the mechanism responsible remains unknown. Using transcriptomic and proteomic approaches in combination with diagnostic biochemical and fluorescent cell-based assays, we show that HHQ exposure leads to prolonged S-phase arrest in phytoplankton coincident with the accumulation of DNA damage and a lack of repair despite the induction of the DNA damage response (DDR). While this effect is reversible, HHQ-exposed phytoplankton were also protected from viral mortality, ascribing a new role of quorum-sensing signals in regulating multitrophic interactions. Furthermore, our data demonstrate that in situ measurements of HHQ coincide with areas of enhanced micro- and nanoplankton biomass. Our results suggest bacterial communication signals as emerging players that may be one of the contributing factors that help structure complex microbial communities throughout the ocean.IMPORTANCE Bacteria and phytoplankton form close associations in the ocean that are driven by the exchange of chemical compounds. The bacterial signal 2-heptyl-4-quinolone (HHQ) slows phytoplankton growth; however, the mechanism responsible remains unknown. Here, we show that HHQ exposure leads to the accumulation of DNA damage in phytoplankton and prevents its repair. While this effect is reversible, HHQ-exposed phytoplankton are also relieved of viral mortality, elevating the ecological consequences of this complex interaction. Further results indicate that HHQ may target phytoplankton proteins involved in nucleotide biosynthesis and DNA repair, both of which are crucial targets for viral success. Our results support microbial cues as emerging players in marine ecosystems, providing a new mechanistic framework for how bacterial communication signals mediate interspecies and interkingdom behaviors.

Characterizing the culturable surface microbiomes of diverse marine animals.

Biofilm-forming bacteria have the potential to contribute to the health, physiology, behavior and ecology of the host and serve as its first line of defense against adverse conditions in the environment. While metabarcoding and metagenomic information furthers our understanding of microbiome composition, fewer studies use cultured samples to study the diverse interactions among the host and its microbiome, as cultured representatives are often lacking. This study examines the surface microbiomes cultured from three shallow-water coral species and two whale species. These unique marine animals place strong selective pressures on their microbial symbionts and contain members under similar environmental and anthropogenic stress. We developed an intense cultivation procedure, utilizing a suite of culture conditions targeting a rich assortment of biofilm-forming microorganisms. We identified 592 microbial isolates contained within 15 bacterial orders representing 50 bacterial genera, and two fungal species. Culturable bacteria from coral and whale samples paralleled taxonomic groups identified in culture-independent surveys, including 29% of all bacterial genera identified in the Megaptera novaeangliae skin microbiome through culture-independent methods. This microbial repository provides raw material and biological input for more nuanced studies which can explore how members of the microbiome both shape their micro-niche and impact host fitness.

Identification of a bacteria-produced benzisoxazole with antibiotic activity against multi-drug resistant Acinetobacter baumannii.

The emergence of multi-drug resistant pathogenic bacteria represents a serious and growing threat to national healthcare systems. Most pressing is an immediate need for the development of novel antibacterial agents to treat Gram-negative multi-drug resistant infections, including the opportunistic, hospital-derived pathogen, Acinetobacter baumannii. Herein we report a naturally occurring 1,2-benzisoxazole with minimum inhibitory concentrations as low as 6.25 µg ml-1 against clinical strains of multi-drug resistant A. baumannii and investigate its possible mechanisms of action. This molecule represents a new chemotype for antibacterial agents against A. baumannii and is easily accessed in two steps via de novo synthesis. In vitro testing of structural analogs suggest that the natural compound may already be optimized for activity against this pathogen. Our results demonstrate that supplementation of 4-hydroxybenzoate in minimal media was able to reverse 1,2-benzisoxazole's antibacterial effects in A. baumannii. A search of metabolic pathways involving 4-hydroxybenzoate coupled with molecular modeling studies implicates two enzymes, chorismate pyruvate-lyase and 4-hydroxybenzoate octaprenyltransferase, as promising leads for the target of 3,6-dihydroxy-1,2-benzisoxazole.

Bacterial alkylquinolone signaling contributes to structuring microbial communities in the ocean.

BACKGROUND: Marine bacteria form complex relationships with eukaryotic hosts, from obligate symbioses to pathogenic interactions. These interactions can be tightly regulated by bioactive molecules, creating a complex system of chemical interactions through which these species chemically communicate thereby directly altering the host's physiology and community composition. Quorum sensing (QS) signals were first described in a marine bacterium four decades ago, and since then, we have come to discover that QS mediates processes within the marine carbon cycle, affects the health of coral reef ecosystems, and shapes microbial diversity and bacteria-eukaryotic host relationships. Yet, only recently have alkylquinolone signals been recognized for their role in cell-to-cell communication and the orchestration of virulence in biomedically relevant pathogens. The alkylquinolone, 2-heptyl-4-quinolone (HHQ), was recently found to arrest cell growth without inducing cell mortality in selected phytoplankton species at nanomolar concentrations, suggesting QS molecules like HHQ can influence algal physiology, playing pivotal roles in structuring larger ecological frameworks. RESULTS: To understand how natural communities of phytoplankton and bacteria respond to HHQ, field-based incubation experiments with ecologically relevant concentrations of HHQ were conducted over the course of a stimulated phytoplankton bloom. Bulk flow cytometry measurements indicated that, in general, exposure to HHQ caused nanoplankton and prokaryotic cell abundances to decrease. Amplicon sequencing revealed HHQ exposure altered the composition of particle-associated and free-living microbiota, favoring the relative expansion of both gamma- and alpha-proteobacteria, and a concurrent decrease in Bacteroidetes. Specifically, Pseudoalteromonas spp., known to produce HHQ, increased in relative abundance following HHQ exposure. A search of representative bacterial genomes from genera that increased in relative abundance when exposed to HHQ revealed that they all have the genetic potential to bind HHQ. CONCLUSIONS: This work demonstrates HHQ has the capacity to influence microbial community organization, suggesting alkylquinolones have functions beyond bacterial communication and are pivotal in driving microbial community structure and phytoplankton growth. Knowledge of how bacterial signals alter marine communities will serve to deepen our understanding of the impact these chemical interactions have on a global scale.

The chemical cue tetrabromopyrrole induces rapid cellular stress and mortality in phytoplankton.

Eukaryotic phytoplankton contribute to the flow of elements through marine food webs, biogeochemical cycles, and Earth's climate. Therefore, how phytoplankton die is a critical determinate of the flow and fate of nutrients. While heterotroph grazing and viral infection contribute to phytoplankton mortality, recent evidence suggests that bacteria-derived cues also control phytoplankton lysis. Here, we report exposure to nanomolar concentrations of 2,3,4,5-tetrabromopyrrole (TBP), a brominated chemical cue synthesized by marine γ-proteobacteria, resulted in mortality of seven phylogenetically-diverse phytoplankton species. A comparison of nine compounds of marine-origin containing a range of cyclic moieties and halogenation indicated that both a single pyrrole ring and increased bromination were most lethal to the coccolithophore, Emiliania huxleyi. TBP also rapidly induced the production of reactive oxygen species and the release of intracellular calcium stores, both of which can trigger the activation of cellular death pathways. Mining of the Ocean Gene Atlas indicated that TBP biosynthetic machinery is globally distributed throughout the water column in coastal areas. These findings suggest that bacterial cues play multiple functions in regulating phytoplankton communities by inducing biochemical changes associated with cellular death. Chemically-induced lysis by bacterial infochemicals is yet another variable that must be considered when modeling oceanic nutrient dynamics.

Biosynthesis of coral settlement cue tetrabromopyrrole in marine bacteria by a uniquely adapted brominase-thioesterase enzyme pair.

Halogenated pyrroles (halopyrroles) are common chemical moieties found in bioactive bacterial natural products. The halopyrrole moieties of mono- and dihalopyrrole-containing compounds arise from a conserved mechanism in which a proline-derived pyrrolyl group bound to a carrier protein is first halogenated and then elaborated by peptidic or polyketide extensions. This paradigm is broken during the marine pseudoalteromonad bacterial biosynthesis of the coral larval settlement cue tetrabromopyrrole (1), which arises from the substitution of the proline-derived carboxylate by a bromine atom. To understand the molecular basis for decarboxylative bromination in the biosynthesis of 1, we sequenced two Pseudoalteromonas genomes and identified a conserved four-gene locus encoding the enzymes involved in its complete biosynthesis. Through total in vitro reconstitution of the biosynthesis of 1 using purified enzymes and biochemical interrogation of individual biochemical steps, we show that all four bromine atoms in 1 are installed by the action of a single flavin-dependent halogenase: Bmp2. Tetrabromination of the pyrrole induces a thioesterase-mediated offloading reaction from the carrier protein and activates the biosynthetic intermediate for decarboxylation. Insights into the tetrabrominating activity of Bmp2 were obtained from the high-resolution crystal structure of the halogenase contrasted against structurally homologous halogenase Mpy16 that forms only a dihalogenated pyrrole in marinopyrrole biosynthesis. Structure-guided mutagenesis of the proposed substrate-binding pocket of Bmp2 led to a reduction in the degree of halogenation catalyzed. Our study provides a biogenetic basis for the biosynthesis of 1 and sets a firm foundation for querying the biosynthetic potential for the production of 1 in marine (meta)genomes.

A Bacterial Quorum-Sensing Precursor Induces Mortality in the Marine Coccolithophore, Emiliania huxleyi.

Interactions between phytoplankton and bacteria play a central role in mediating biogeochemical cycling and food web structure in the ocean. However, deciphering the chemical drivers of these interspecies interactions remains challenging. Here, we report the isolation of 2-heptyl-4-quinolone (HHQ), released by Pseudoalteromonas piscicida, a marine gamma-proteobacteria previously reported to induce phytoplankton mortality through a hitherto unknown algicidal mechanism. HHQ functions as both an antibiotic and a bacterial signaling molecule in cell-cell communication in clinical infection models. Co-culture of the bloom-forming coccolithophore, Emiliania huxleyi with both live P. piscicida and cell-free filtrates caused a significant decrease in algal growth. Investigations of the P. piscicida exometabolome revealed HHQ, at nanomolar concentrations, induced mortality in three strains of E. huxleyi. Mortality of E. huxleyi in response to HHQ occurred slowly, implying static growth rather than a singular loss event (e.g., rapid cell lysis). In contrast, the marine chlorophyte, Dunaliella tertiolecta and diatom, Phaeodactylum tricornutum were unaffected by HHQ exposures. These results suggest that HHQ mediates the type of inter-domain interactions that cause shifts in phytoplankton population dynamics. These chemically mediated interactions, and other like it, ultimately influence large-scale oceanographic processes.

Enhancement of antibiotic activity against multidrug-resistant bacteria by the efflux pump inhibitor 3,4-dibromopyrrole-2,5-dione isolated from a Pseudoalteromonas sp.

Members of the resistance nodulation cell division (RND) of efflux pumps play essential roles in multidrug resistance (MDR) in Gram-negative bacteria. Here, we describe the search for new small molecules from marine microbial extracts to block efflux and thus restore antibiotic susceptibility in MDR bacterial strains. We report the isolation of 3,4-dibromopyrrole-2,5-dione (1), an inhibitor of RND transporters, from Enterobacteriaceae and Pseudomonas aeruginosa, from the marine bacterium Pseudoalteromonas piscicida. 3,4-Dibromopyrrole-2,5-dione decreased the minimum inhibitory concentrations (MICs) of two fluoroquinolones, an aminoglycoside, a macrolide, a beta-lactam, tetracycline, and chloramphenicol between 2- and 16-fold in strains overexpressing three archetype RND transporters (AcrAB-TolC, MexAB-OprM, and MexXY-OprM). 3,4-Dibromopyrrole-2,5-dione also increased the intracellular accumulation of Hoechst 33342 in wild-type but not in transporter-deficient strains and prevented H33342 efflux (IC50 = 0.79 µg/mL or 3 µM), a hallmark of efflux pump inhibitor (EPI) functionality. A metabolomic survey of 36 Pseudoalteromonas isolates mapped the presence of primarily brominated metabolites only within the P. piscicida phylogenetic clade, where a majority of antibiotic activity was also observed, suggesting a link between halogenation and enhanced secondary metabolite biosynthetic potential. In sum, 3,4-dibromopyrrole-2,5-dione is a potent EPI and deserves further attention as an adjuvant to enhance the effectiveness of existing antibiotics.