Prevalence and molecular characterisation of carbapenemase-producing Enterobacterales in an outbreak-free setting in a single hospital in Uruguay.

OBJECTIVES: This study aimed to characterise all carbapenemase-producing enterobacteria (CPE) isolates obtained from an outbreak-free setting in Uruguay. METHODS: We studied 12 CPE isolated from Hospital de Clínicas between 2012-2016. Bacterial identification and antibiotic susceptibility testing were performed using VITEK®2 and Sensititre or agar dilution, respectively. Antimicrobial resistance genes and mobile genetic elements were identified by PCR and sequencing. Multilocus sequence typing was performed for Klebsiella pneumoniae. Plasmid conjugation was assessed, plasmid size was estimated by S1-PFGE and plasmid incompatibility groups were sought by PCR. RESULTS: Among 8364 enterobacteria, 12 CPE were isolated from urine, blood culture, wound, peritoneal fluid and punch samples. NDM-1 was the most prevalent carbapenemase, followed by VIM-2 and KPC-2. All isolates were resistant to gentamicin, cefotaxime, ceftazidime, trimethoprim/sulfamethoxazole, ciprofloxacin and imipenem and were susceptible to fosfomycin. We characterised six class 1 integrons: dfrA12-orfF-aadA2; aacA4-blaOXA-2-orfD; aadB-aadA2; dfrA1; aadB-blaOXA-10-aadA1; and blaVIM-2-dfrA7. An association between various aminoglycoside, ß-lactam and fluoroquinolone resistance genes were observed, some of them located in transferable plasmids belonging to incompatibility groups IncC, IncHI1 and IncM1. We described a new composite transposon (assigned Tn6935) including blaNDM-1 flanked by two directly-oriented copies of a Tn3-like element ISKox2-like family transposase. The sequence types of K. pneumoniae isolates were ST11, ST14 and ST661. CONCLUSIONS: The presence of CPE is sporadic and could be due to measures taken by the Public Health Committee. Nevertheless, the coexistence of several resistance mechanisms and their presence in conjugative plasmids and high-risk clones is worrisome.

Estrogen receptors in breast and bone: from virtue of remodeling to vileness of metastasis.

Bone metastasis is a prominent cause of morbidity and mortality in cancer. High rates of bone colonization in breast cancer, especially in the subtype expressing estrogen receptors (ERs), suggest tissue-specific proclivities for metastatic tumor formation. The mechanisms behind this subtype-specific organ-tropism remains largely elusive. Interestingly, as the major driver of ER+ breast cancer, ERs also have important roles in bone development and homeostasis. Thus, any agents targeting ER will also inevitably affect the microenvironment, which involves the osteoblasts and osteoclasts. Yet, how such microenvironmental effects are integrated with direct therapeutic responses of cancer cells remain poorly understood. Recent findings on ER mutations, especially their enrichment in bone metastasis, raised even more provocative questions on the role of ER in cancer-bone interaction. In this review, we evaluate the importance of ERs in bone metastasis and discuss new avenues of investigation for bone metastasis treatment based on current knowledge.

Allodemic distribution of plasmids co-harbouring blaCTX-M-15/aac(6')-Ib-cr/qnrB in Klebsiella pneumoniae is the main source of extended-spectrum ß-lactamases in Uruguay's paediatric hospital.

OBJECTIVES: This study aimed to describe the characteristics of clinical isolates of extended-spectrum ß-lactamase (ESBL)-producing enterobacteria (EPE) in Uruguay's paediatric hospital. METHODS: ESBLs, qnr alleles and aac(6')-Ib-cr were sought and characterised in EPE isolated between March 2010 and March 2012. Transfer of resistance determinants was assessed by conjugation. Incompatibility (Inc) groups, plasmid toxin-antitoxin systems (TAS) and plasmid size were determined in transconjugants. Clonality was analysed by pulsed-field gel electrophoresis. Multilocus sequence typing was done for ESBL-producing Klebsiella pneumoniae. RESULTS: A total of 77 EPE isolates were characterised, comprising 43% K. pneumoniae, 19.5% Serratia marcescens, 19.5% Escherichia coli, 17% Enterobacter cloacae and 1% Klebsiella oxytoca. ESBLs belonged mainly to the blaCTX-M family (69.6%) [blaCTX-M-15 (45%) and blaCTX-M-2 (31%)]. The aac(6')-Ib-cr/qnrB duplex was the most frequently detected plasmid-mediated quinolone resistance mechanism; this association was detected in K. pneumoniae harbouring blaCTX-M-15. Transconjugants were obtained for 71% of the EPE. Amongst transconjugants, certain combinations were found between ESBLs and Inc group, e.g. IncA/C-blaCTX-M-2, IncHI1/HI2-blaCTX-M-9 and IncHI1/HI2-blaSHV-12. In addition, the combination ccdAB-blaCTX-M-15 was also found. K. pneumoniae isolates harbouring blaCTX-M-15/aac(6')-Ib-cr/qnrB showed allodemic behaviour, with a predominance of ST14, ST45 and ST48. CONCLUSIONS: In this study, epidemiological changes in ESBL distribution could be explained by the spread of K. pneumoniae harbouring blaCTX-M-15/aac(6')-Ib-cr/qnrB, encoded mainly on conjugative plasmids featuring ccdAB TAS. Since reports of TAS in K. pneumoniae plasmids are scarce, new strategies are needed to combat intrinsic selection pressure exerted by the association, in conjugative plasmids, of resistance mechanisms with TAS.

ERß decreases breast cancer cell survival by regulating the IRE1/XBP-1 pathway.

Unfolded protein response (UPR) is an adaptive reaction that allows cancer cells to survive endoplasmic reticulum (EnR) stress that is often induced in the tumor microenvironment because of inadequate vascularization. Previous studies report an association between activation of the UPR and reduced sensitivity to antiestrogens and chemotherapeutics in estrogen receptor α (ERα)-positive and triple-negative breast cancers, respectively. ERα has been shown to regulate the expression of a key mediator of the EnR stress response, the X-box-binding protein-1 (XBP-1). Although network prediction models have associated ERß with the EnR stress response, its role as regulator of the UPR has not been experimentally tested. Here, upregulation of wild-type ERß (ERß1) or treatment with ERß agonists enhanced apoptosis in breast cancer cells in the presence of pharmacological inducers of EnR stress. Targeting the BCL-2 to the EnR of the ERß1-expressing cells prevented the apoptosis induced by EnR stress but not by non-EnR stress apoptotic stimuli indicating that ERß1 promotes EnR stress-regulated apoptosis. Downregulation of inositol-requiring kinase 1α (IRE1α) and decreased splicing of XBP-1 were associated with the decreased survival of the EnR-stressed ERß1-expressing cells. ERß1 was found to repress the IRE1 pathway of the UPR by inducing degradation of IRE1α. These results suggest that the ability of ERß1 to target the UPR may offer alternative treatment strategies for breast cancer.

First report of the ceftazidimase CTX-M-19 in South America.

We report the first detection of bla CTX-M-19 in South America, harboured in an Escherichia coli isolate obtained from a urine sample; such an isolate belonged to phylogenetic group A, ST603, and showed a ceftazidimase profile. bla CTX-M-19 was encoded in an approximately 100 kb IncI1/IncF conjugative plasmid, featuring pndAC and hok/sok addiction systems; the ß-lactamase gene was flanked upstream by three tandem-like transposons (IS26, IS10 and ISEcp1), inserted one inside the other, and downstream by IS903.