Interstitial cystitis/bladder pain syndrome (IC) is associated with significant morbidity, yet underlying mechanisms and diagnostic biomarkers remain unknown. Pelvic organs exhibit neural crosstalk by convergence of visceral sensory pathways, and rodent studies demonstrate distinct bacterial pain phenotypes, suggesting that the microbiome modulates pelvic pain in IC. Stool samples were obtained from female IC patients and healthy controls, and symptom severity was determined by questionnaire. Patients with urologic chronic pelvic pain syndromes (UCPPS) suffer chronic pelvic pain and dramatically lower quality of life, yet diagnostic markers and effective therapies remain elusive for these costly syndromes 1 . Interstitial cystitis/bladder pain syndrome (IC/BPS or IC) is a debilitating UCPPS condition of pelvic pain and voiding dysfunction that afflicts as many as 8 million U.S. women where depression is a common co-morbidity 2-5 . IC etiology remains unknown, but urothelial lesions and lamina propria mast cells are associated with patient symptoms [6][7][8] . HPA axis dysfunction has been implicated in female and male patients and cats with feline IC 9-13 , and thus may be common among UCPPS, but mechanisms that integrate pelvic pain, voiding dysfunction, HPA activity, and depression are lacking. Because of these long-standing questions, NIDDK has launched its flagship urology study, the Multi-Disciplinary Approaches to Chronic Pelvic Pain (MAPP) Research Network with the most comprehensive studies to date of UCPPS including clinical characterization and epidemiologic and mechanistic studies 14,15 . Operational taxonomic units (OTUsThe microbiome is increasingly appreciated as driving diverse physiologic processes in both health and disease 16,17 . With the notable exception of C. difficile colitis, early studies implicated pathogenic dysbioses primarily at the phylum and genus levels, but more recent studies identify individual species associated with disease. Moreover, individual species within the microbiome have recently been associated with driving disease through altered innate metabolism or altered pharmaceutical metabolism 18 . Despite these advances, it remains unclear whether microbiota contribute to pain syndromes generally and to UCPPS in particular. Consistent with the recent finding of a normal female urinary microbiome 19 , the MAPP Network is also exploring UCPPS microbiota with a focus on the urinary microbiome. MAPP Network studies have identified an association between fungi

Stenotrophomonas maltophilia is an emerging opportunistic and nosocomial pathogen. S. maltophilia is also a risk factor for lung exacerbations in cystic fibrosis patients. S. maltophilia attaches to various mammalian cells, and we recently documented that the bacterium encodes a type II secretion system which triggers detachment-induced apoptosis in lung epithelial cells. We have now confirmed that S. maltophilia also encodes a type IVA secretion system (VirB/VirD4 [VirB/D4] T4SS) that is highly conserved among S. maltophilia strains and, looking beyond the Stenotrophomonas genus, is most similar to the T4SS of Xanthomonas. To define the role(s) of this T4SS, we constructed a mutant of strain K279a that is devoid of secretion activity due to loss of the VirB10 component. The mutant induced a higher level of apoptosis upon infection of human lung epithelial cells, indicating that a T4SS effector(s) has antiapoptotic activity. However, when we infected human macrophages, the mutant triggered a lower level of apoptosis, implying that the T4SS also elaborates a proapoptotic factor(s). Moreover, when we cocultured K279a with strains of Pseudomonas aeruginosa, the T4SS promoted the growth of S. maltophilia and reduced the numbers of heterologous bacteria, signaling that another effector(s) has antibacterial activity. In all cases, the effect of the T4SS required S. maltophilia contact with its target. Thus, S. maltophilia VirB/D4 T4SS appears to secrete multiple effectors capable of modulating death pathways. That a T4SS can have anti- and prokilling effects on different targets, including both human and bacterial cells, has, to our knowledge, not been seen before.

Stenotrophomonas maltophilia, a Gram-negative, multi-drug-resistant bacterium, is increasingly recognized as a key opportunistic pathogen. Thus, we embarked upon an investigation of S. maltophilia iron acquisition. To begin, we determined that the genome of strain K279a is predicted to encode a complete siderophore system, including a biosynthesis pathway, an outer-membrane receptor for ferrisiderophore, and other import and export machinery. Compatible with these data, K279a and other clinical isolates of S. maltophilia secreted a siderophore-like activity when grown at 25-37 °C in low-iron media, as demonstrated by a chrome azurol S assay, which detects iron chelation, and Arnow and Rioux assays, which detect catecholate structures. Importantly, these supernatants rescued the growth of iron-starved S. maltophilia, documenting the presence of a biologically active siderophore. A mutation in one of the predicted biosynthesis genes (entC) abolished production of the siderophore and impaired bacterial growth in low-iron conditions. Inactivation of the putative receptor gene (fepA) prevented the utilization of siderophore-containing supernatants for growth in low-iron conditions. Although the biosynthesis and import loci showed some similarity to those of enterobactin, a well-known catecholate made by enteric bacteria, the siderophore of K279a was unable to rescue the growth of an enterobactin-utilizing indicator strain, and conversely iron-starved S. maltophilia could not use purified enterobactin. Furthermore, the S. maltophilia siderophore displayed patterns of solubility in organic compounds and mobility upon thin-layer chromatography that were distinct from those of enterobactin and its derivative, salmochelin. Together, these data demonstrate that S. maltophilia secretes a novel catecholate siderophore.

S. maltophilia is an increasingly important opportunistic pathogen. Inherently resistant to many antibiotics, S. maltophilia is often associated with lung infection, being, among other things, a complicating factor in cystic fibrosis patients.

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