Virulence attributes of successful methicillin-resistant Staphylococcus aureus lineages.

Methicillin-resistant Staphylococcus aureus (MRSA) is a leading cause of severe and often fatal infections. MRSA epidemics have occurred in waves, whereby a previously successful lineage has been replaced by a more fit and better adapted lineage. Selection pressures in both hospital and community settings are not uniform across the globe, which has resulted in geographically distinct epidemiology. This review focuses on the mechanisms that trigger the establishment and maintenance of current, dominant MRSA lineages across the globe. While the important role of antibiotic resistance will be mentioned throughout, factors which influence the capacity of S. aureus to colonize and cause disease within a host will be the primary focus of this review. We show that while MRSA possesses a diverse arsenal of toxins including alpha-toxin, the success of a lineage involves more than just producing toxins that damage the host. Success is often attributed to the acquisition or loss of genetic elements involved in colonization and niche adaptation such as the arginine catabolic mobile element, as well as the activity of regulatory systems, and shift metabolism accordingly (e.g., the accessory genome regulator, agr). Understanding exactly how specific MRSA clones cause prolonged epidemics may reveal targets for therapies, whereby both core (e.g., the alpha toxin) and acquired virulence factors (e.g., the Panton-Valentine leukocidin) may be nullified using anti-virulence strategies.

Primary thromboprophylaxis in cancer outpatients - real-world evidence.

INTRODUCTION: Cancer-associated thrombosis (CAT) is a significant concern among patients with malignant diseases, leading to increased mortality. While current guidelines recommend primary thromboprophylaxis for venous thromboembolism (VTE) in medium-to-high-risk outpatients, this practice remains controversial. A better understanding of primary thromboprophylaxis is crucial, yet there is a lack of Real-World Evidence (RWE) in Portugal. AIMS: This RWE study aimed to elucidate primary thromboprophylaxis practices among cancer outpatients in Portugal. METHODS: A five-year observational multicentric study in eight Portuguese health institutions enrolled 124 adult cancer outpatients under primary thromboprophylaxis for VTE. The endpoints were CAT, bleeding, cancer progression and death. RESULTS: High thrombotic risk tumours were prevalent, with 57% (71) of the patients presenting with pancreatic and gastric cancers. Regarding primary thromboprophylaxis, 55% (68) received Low-Molecular-Weight Heparin (LMWH). VTE was presented in 11% (14) of the patients and major bleeding in 2% (2). Vascular compression, elevated D-dimer and previous VTE were significantly associated with VTE occurrence under primary thromboprophylaxis. The Onkotev model was shown to be the best risk assessment model (RAM) in this population (p = 0.007). CAT patients exhibited a lower progression-free survival than non-CAT patients (p = 0.021), while thrombosis did not influence overall survival (p = 0.542). CONCLUSION: Primary thromboprophylaxis in medium-to-high-risk cancer outpatients is a safe and effective practice in real-world settings. This study is the first Portuguese RWE on primary thromboprophylaxis, highlighting evidence for improving prophylactic strategies in this population.

Endoplasmic Reticulum Stress in Renal Cell Carcinoma.

The endoplasmic reticulum is an organelle exerting crucial functions in protein production, metabolism homeostasis and cell signaling. Endoplasmic reticulum stress occurs when cells are damaged and the capacity of this organelle to perform its normal functions is reduced. Subsequently, specific signaling cascades, together forming the so-called unfolded protein response, are activated and deeply impact cell fate. In normal renal cells, these molecular pathways strive to either resolve cell injury or activate cell death, depending on the extent of cell damage. Therefore, the activation of the endoplasmic reticulum stress pathway was suggested as an interesting therapeutic strategy for pathologies such as cancer. However, renal cancer cells are known to hijack these stress mechanisms and exploit them to their advantage in order to promote their survival through rewiring of their metabolism, activation of oxidative stress responses, autophagy, inhibition of apoptosis and senescence. Recent data strongly suggest that a certain threshold of endoplasmic reticulum stress activation needs to be attained in cancer cells in order to shift endoplasmic reticulum stress responses from a pro-survival to a pro-apoptotic outcome. Several endoplasmic reticulum stress pharmacological modulators of interest for therapeutic purposes are already available, but only a handful were tested in the case of renal carcinoma, and their effects in an in vivo setting remain poorly known. This review discusses the relevance of endoplasmic reticulum stress activation or suppression in renal cancer cell progression and the therapeutic potential of targeting this cellular process for this cancer.

S100 Proteins in Fatty Liver Disease and Hepatocellular Carcinoma.

Non-alcoholic fatty liver disease (NAFLD) is a highly prevalent and slow progressing hepatic pathology characterized by different stages of increasing severity which can ultimately give rise to the development of hepatocellular carcinoma (HCC). Besides drastic lifestyle changes, few drugs are effective to some extent alleviate NAFLD and HCC remains a poorly curable cancer. Among the deregulated molecular mechanisms promoting NAFLD and HCC, several members of the S100 proteins family appear to play an important role in the development of hepatic steatosis, non-alcoholic steatohepatitis (NASH) and HCC. Specific members of this Ca2+-binding protein family are indeed significantly overexpressed in either parenchymal or non-parenchymal liver cells, where they exert pleiotropic pathological functions driving NAFLD/NASH to severe stages and/or cancer development. The aberrant activity of S100 specific isoforms has also been reported to drive malignancy in liver cancers. Herein, we discuss the implication of several key members of this family, e.g., S100A4, S100A6, S100A8, S100A9 and S100A11, in NAFLD and HCC, with a particular focus on their intracellular versus extracellular functions in different hepatic cell types. Their clinical relevance as non-invasive diagnostic/prognostic biomarkers for the different stages of NAFLD and HCC, or their pharmacological targeting for therapeutic purpose, is further debated.

Hepatic PTEN Signaling Regulates Systemic Metabolic Homeostasis through Hepatokines-Mediated Liver-to-Peripheral Organs Crosstalk.

Liver-derived circulating factors deeply affect the metabolism of distal organs. Herein, we took advantage of the hepatocyte-specific PTEN knockout mice (LPTENKO), a model of hepatic steatosis associated with increased muscle insulin sensitivity and decreased adiposity, to identify potential secreted hepatic factors improving metabolic homeostasis. Our results indicated that protein factors, rather than specific metabolites, released by PTEN-deficient hepatocytes trigger an improved muscle insulin sensitivity and a decreased adiposity in LPTENKO. In this regard, a proteomic analysis of conditioned media from PTEN-deficient primary hepatocytes identified seven hepatokines whose expression/secretion was deregulated. Distinct expression patterns of these hepatokines were observed in hepatic tissues from human/mouse with NAFLD. The expression of specific factors was regulated by the PTEN/PI3K, PPAR or AMPK signaling pathways and/or modulated by classical antidiabetic drugs. Finally, loss-of-function studies identified FGF21 and the triad AHSG, ANGPTL4 and LECT2 as key regulators of insulin sensitivity in muscle cells and in adipocytes biogenesis, respectively. These data indicate that hepatic PTEN deficiency and steatosis alter the expression/secretion of hepatokines regulating insulin sensitivity in muscles and the lipid metabolism in adipose tissue. These hepatokines could represent potential therapeutic targets to treat obesity and insulin resistance.

Preoperative color Doppler ultrasound parameters for surgical decision-making in upper arm arteriovenous fistula maturation.

OBJECTIVE: Current scientific evidence is insufficient to determine the best vascular access for each patient. It is an unmet clinical need because vascular access dysfunction accounts for 20% to 30% of hospital admissions. Our aim was to evaluate preoperative color flow Doppler ultrasound (CDUS)-derived parameters (vein diameter and brachial artery flow and diameter) and their effect interaction with comorbidities as predictors of brachiocephalic (BC) and brachiobasilic (BB) arteriovenous fistula (AVF) maturation. METHODS: A prospective analysis was performed of patients who underwent BC and BB AVF as primary definitive vascular access between January 2016 and May 2017. Variables included patients' demographics, comorbidities, medication, preoperative blood pressure, and CDUS-derived parameters. Outcomes were patency 48 hours after surgery and fistula maturation at 6 and 12 weeks. Nonparametric descriptive and univariate statistics were used. Logistic regression models and receiver operating characteristic curve analyses were performed. RESULTS: There were 132 patients (91 with BC AVF and 41 with BB AVF) included. The 48-hour patency was 91.7%. AVF maturation at 6 weeks was observed in 71.3%, and AVF maturation at 12 weeks was observed in 66.3%. There were no associations in univariate and multivariate logistic regression analysis between AVF maturation and comorbidities. Systolic blood pressure was an independent predictor of 48-hour patency with an optimized cutoff of 154 mm Hg (area under the curve, 0.73; P = .013; Youden index, 0.40). Vein diameter with tourniquet was an independent predictor of AVF maturation at 6 and 12 weeks with an optimized cutoff of 3.9 mm (area under the curve, 0.74; P < .001; Youden index, 0.38). CONCLUSIONS: AVF maturation was independent of comorbidities. Systolic blood pressure ≥154 mm Hg and vein diameter with tourniquet ≥3.9 mm were the associated conditions that better predicted BC and BB AVF maturation. There were no effect interactions between CDUS-derived parameters and associated comorbidities.

Searching for the Best Transthyretin Aggregation Protocol to Study Amyloid Fibril Disruption.

Several degenerative amyloid diseases, with no fully effective treatment, affect millions of people worldwide. These pathologies-amyloidoses-are known to be associated with the formation of ordered protein aggregates and highly stable and insoluble amyloid fibrils, which are deposited in multiple tissues and organs. The disruption of preformed amyloid aggregates and fibrils is one possible therapeutic strategy against amyloidosis; however, only a few compounds have been identified as possible fibril disruptors in vivo to date. To properly identify chemical compounds as potential fibril disruptors, a reliable, fast, and economic screening protocol must be developed. For this purpose, three amyloid fibril formation protocols using transthyretin (TTR), a plasma protein involved in several amyloidoses, were studied using thioflavin-T fluorescence assays, circular dichroism (CD), turbidity, dynamic light scattering (DLS), and transmission electron microscopy (TEM), in order to characterize and select the most appropriate fibril formation protocol. Saturation transfer difference nuclear magnetic resonance spectroscopy (STD NMR) was successfully used to study the interaction of doxycycline, a known amyloid fibril disruptor, with preformed wild-type TTR (TTRwt) aggregates and fibrils. DLS and TEM were also used to characterize the effect of doxycycline on TTRwt amyloid species disaggregation. A comparison of the TTR amyloid morphology formed in different experimental conditions is also presented.

Occurrence of NDM-1-producing Morganella morganii and Proteus mirabilis in a single patient in Portugal: probable in vivo transfer by conjugation.

OBJECTIVES: To decipher the genetics of acquisition of carbapenemase-encoding genes identified in two carbapenem-resistant Enterobacteriaceae recovered from a single patient in Portugal. METHODS: Carbapenemase genes were searched by PCR assays and mating-out assays were performed to further characterize the plasmid support of the carbapenemase genes. Genetic characterization of the plasmid supports was performed by whole-plasmid sequencing using the Illumina technology. RESULTS: We identified here two NDM-1-producing isolates, namely a Morganella morganii and a Proteus mirabilis, sharing the same blaNDM-1-positive plasmid. This 154 kb plasmid belonged to the IncA/C2 type, recently renamed IncC, and co-harboured two AmpC ß-lactamase genes, namely blaCMY-4 and blaDHA-1, in addition to the 16S rRNA methylase gene armA encoding high-level resistance to aminoglycosides. In addition, the M. morganii isolate produced the CTX-M-33 extended-spectrum ß-lactamase possessing weak carbapenemase activity, encoded by another plasmid. CONCLUSIONS: We showed here that, in addition to KPC-type and OXA-181 carbapenemases, which have been identified as widespread in this country, another concern is the emergence of NDM-1-producing enterobacterial isolates in Portugal. We demonstrated here the in vivo plasmid transfer of a blaNDM-1-positive plasmid leading to dissemination of this carbapenemase gene within different enterobacterial species in a single patient.

Intestinal carriage of extended-spectrum beta-lactamase-producing Enterobacteriaceae at admission in a Portuguese hospital.

To evaluate the prevalence of extended-spectrum ß-lactamase (ESBL)-producing Enterobacteriaceae fecal carriers at admission in a Portuguese hospital and to determine the epidemiology and antimicrobial resistance patterns of ESBL-producing isolates. During a 2-month period, rectal swabs were collected at hospital admission from 151 at-risk patients. In addition, 48 rectal swabs were obtained from weekly screenings of 37 patients hospitalized for > 48 h. All ESBL/carbapenemase-producing isolates were tested for antimicrobial susceptibility and characterized by PFGE and MLST. The prevalence of ESBL producers at hospital admission was 17% and 24% among at-risk patients hospitalized for > 48 h, while the prevalence of carbapenemase producers was 3% in both cases. Most of the isolates were Escherichia coli (54%) and Klebsiella pneumoniae (41%). The most common ESBL identified was CTX-M-15 (n = 17/34; 50%), followed by CTX-M-27 (n = 10; 29%), CTX-M-33 (n = 4; 12%), SHV-12 (n = 2), and CTX-M-55 (n = 1). The 20 E. coli isolates were distributed into 16 PFGE types and nine sequence types (ST), with 60% of the isolates belonging to ST131. The 15 K. pneumoniae were grouped into 12 PFGE types and nine STs, with three STs (ST17, ST449, ST147) corresponding to 60% of the isolates. A high proportion of isolates showed resistance to ciprofloxacin (86%), trimethoprim-sulfamethoxazole (68%), tobramycin (57%), and gentamicin (43%). All isolates remained susceptible to fosfomycin. A high prevalence of ESBL-producing Enterobacteriaceae was found at hospital admission among at-risk patients and > 50% of the isolates showed resistance to first-line antibiotics for the treatment of lower urinary tract infections, leaving fosfomycin as an alternative.

mRNA Post-Transcriptional Regulation by AU-Rich Element-Binding Proteins in Liver Inflammation and Cancer.

AU-rich element-binding proteins (AUBPs) represent important post-transcriptional regulators of gene expression. AUBPs can bind to the AU-rich elements present in the 3'-UTR of more than 8% of all mRNAs and are thereby able to control the stability and/or translation of numerous target mRNAs. The regulation of the stability and the translation of mRNA transcripts by AUBPs are highly complex processes that occur through multiple mechanisms depending on the cell type and the cellular context. While AUBPs have been shown to be involved in inflammatory processes and the development of various cancers, their important role and function in the development of chronic metabolic and inflammatory fatty liver diseases (FLDs), as well as in the progression of these disorders toward cancers such as hepatocellular carcinoma (HCC), has recently started to emerge. Alterations of either the expression or activity of AUBPs are indeed significantly associated with FLDs and HCC, and accumulating evidence indicates that several AUBPs are deeply involved in a significant number of cellular processes governing hepatic metabolic disorders, inflammation, fibrosis, and carcinogenesis. Herein, we discuss our current knowledge of the roles and functions of AUBPs in liver diseases and cancer. The relevance of AUBPs as potential biomarkers for different stages of FLD and HCC, or as therapeutic targets for these diseases, are also highlighted.

miRNAs and NAFLD: from pathophysiology to therapy.

Non-alcoholic fatty liver disease (NAFLD) is associated with a thorough reprogramming of hepatic metabolism. Epigenetic mechanisms, in particular those associated with deregulation of the expressions and activities of microRNAs (miRNAs), play a major role in metabolic disorders associated with NAFLD and their progression towards more severe stages of the disease. In this review, we discuss the recent progress addressing the role of the many facets of complex miRNA regulatory networks in the development and progression of NAFLD. The basic concepts and mechanisms of miRNA-mediated gene regulation as well as the various setbacks encountered in basic and translational research in this field are debated. miRNAs identified so far, whose expressions/activities are deregulated in NAFLD, and which contribute to the outcomes of this pathology are further reviewed. Finally, the potential therapeutic usages in a short to medium term of miRNA-based strategies in NAFLD, in particular to identify non-invasive biomarkers, or to design pharmacological analogues/inhibitors having a broad range of actions on hepatic metabolism, are highlighted.

Epidemiology of Carbapenemase-Producing Klebsiella pneumoniae in a Hospital, Portugal.

We aimed to provide updated epidemiologic data on carbapenem-resistant Klebsiella pneumoniae in Portugal by characterizing all isolates (N = 46) recovered during 2013-2018 in a 123-bed hospital in Lisbon. We identified blaKPC-3 (n = 36), blaOXA-181 (n = 9), and blaGES-5 (n = 8) carbapenemase genes and observed co-occurrence of blaKPC-3 and blaGES-5 in 7 isolates. A single GES-5-producing isolate co-produced the extended-spectrum ß-lactamase BEL-1; both corresponding genes were co-located on the same ColE1-like plasmid. The blaOXA-181 gene was always located on an IncX3 plasmid, whereas blaKPC-3 was carried on IncN, IncFII, IncFIB, and IncFIIA plasmid types. The 46 isolates were distributed into 13 pulsotypes and 9 sequence types. All isolates remained susceptible to ceftazidime/avibactam, but some exhibited reduced antimicrobial susceptibility (MIC = 3 mg/L).

CTX-M-33, a CTX-M-15 derivative conferring reduced susceptibility to carbapenems.

CTX-M-type extended-spectrum ß-lactamases (ESBL) are widespread among Enterobacterales worldwide. The most common variant is CTX-M-15 hydrolyzing ceftazidime at high rate, but sparing carbapenems. We identified here CTX-M-33, a point mutant derivative of CTX-M-15 (Asp to Ser substitution at Ambler position 109), exhibiting a low carbapenemase activity. ß-Lactamase CTX-M-33 was identified in a Klebsiella pneumoniae isolate belonging to ST405, lacking the outer membrane protein OmpK36, that was resistant to broad-spectrum cephalosporins and ß-lactam/ß-lactamase inhibitor combinations, and displayed a decreased susceptibility to carbapenems. Comparative hydrolytic activity assays showed that CTX-M-33 hydrolyzed ceftazidime at a lower level than CTX-M-15, but significantly hydrolyzed meropenem. In addition, CTX-M-33 showed higher Mutant Prevention Concentration values and wider mutant selection window in presence of meropenem, in accordance with its observed hydrolytic properties. We identified here the very first CTX-M enzyme possessing a weak carbapenemase activity, that may correspond to an emerging phenomenon when considering its possibility to evolve from the widespread ESBL CTX-M-15.

Staphylococcus aureus nasal carriage among homeless population in Lisbon, Portugal.

Methicillin-resistant Staphylococcus aureus (MRSA) nasal carriage is a major risk factor for infection, namely among populations in the community with inherent prompting factors, such as the homeless. In Portugal, there are no data on S. aureus/MRSA nasal carriage among the homeless community. A total of 84 homeless individuals living in Lisbon (34 with no permanent address and 50 living in shelter) were nasally screened for S. aureus/ MRSA. All isolates were characterized to determine antimicrobial susceptibility and clonal type. A total of 43 (51.2%) S. aureus carriers were identified, including a single individual colonized with MRSA (1.2%). S. aureus carriage rate was higher among individuals with no permanent address (58.8% versus 46%), younger (45.7 ± 12.7 versus 52.5 ± 10.8 years), and with diagnosis of asthma (9% versus 0%). The single MRSA belonged to the EMRSA-15 clone (PFGE D, ST15-SCCmec IVh, and spa type t790). Almost half of the methicillin-susceptible S. aureus (MSSA) isolates (41.9%, n = 18) belonged to two major clones, ST398-t1451 (n = 13) and ST30-t399/t11980/t12808 associated with PFGE I (n = 5). A high proportion of isolates showed non-susceptibility to mupirocin (64%), erythromycin (45%), and fusidic acid (20%) and induced resistance to clindamycin (39%). None of the isolates harboured PVL. Our results suggest that the homeless population of Lisbon does not constitute a reservoir of MRSA in the community, but harbour the highly transmissible ST398-t1451 MSSA lineage.

Understanding the skin sensitization capacity of ascaridole: a combined study of chemical reactivity and activation of the innate immune system (dendritic cells) in the epidermal environment.

To improve the prediction of the possible allergenicity of chemicals in contact with the skin, investigations of upstream events are required to better understand the molecular mechanisms involved in the initiation of allergic reactions. Ascaridole, one of the compounds responsible for skin sensitization to aged tea tree oil, degrades into intermediates that evolve via different mechanisms involving radical species. We aimed at broadening the knowledge about the contribution of radical intermediates derived from ascaridole to the skin sensitization process by assessing the reactivity profile towards amino acids, identifying whether free radicals are formed in a reconstructed human epidermis (RHE) model and their biological properties to activate the immune system, namely dendritic cells in their natural context of human HaCaT keratinocytes and RHE. Electron paramagnetic resonance combined to spin-trapping in EpiSkin™ RHE confirmed the formation of C-radicals in the epidermal tissue from 10 mM ascaridole concentration, while reactivity studies toward amino acids showed electrophilic intermediates issued from radical rearrangements of ascaridole as the main reactive species. Activation of THP-1 cells, as surrogate for dendritic cells, that were cocultured with HaCaT was significantly upregulated after treatment with low micromolar concentrations based on cell surface expression of the co-stimulatory molecule CD86 and the adhesion molecule CD54. Placing THP-1 cells underneath the RHE allowed us to monitor which of the concentrations that produce radical(s) and/or protein antigens in the epidermal skin environment promote the activation of dendritic cells. We detected no significant upregulation of CD86/CD54 after topical RHE application of concentrations up to 30 mM ascaridole (t = 24 h) but clear upregulation after 60 mM.

Sensitization potential and potency of terpene hydroperoxides in the cocultured activation test method.

BACKGROUND: Positive patch test reactions to mixtures of oxidized terpenes containing allergenic hydroperoxides are frequently reported. However, human sensitization data for these hydroperoxides are not available. OBJECTIVES: To analyse and evaluate the human sensitization potential and potency of hydroperoxides in vitro by using human cells. MATERIALS/METHODS: Limonene-1-hydroperoxide, limonene-2-hydroperoxide, citronellol-7-hydroperoxide, cumene hydroperoxide, 1-(1-hydroperoxy-1-methylethyl)cyclohexene and mixtures of citronellol hydroperoxides (isomers at positions 6 and 7) and linalool hydroperoxides (isomers at positions 6 and 7) were studied. All compounds were synthesized except for cumene hydroperoxide, which was commercially available. Their potential and potency to activate dendritic cells (DCs) was evaluated by measuring the upregulation of CD86 and CD54 on THP-1 cells upon exposure in the cocultured activation test (COCAT) consisting of HaCaT cells (human keratinocyte cell line) and THP-1 monocytes (as a surrogate for DCs). RESULTS: Hydroperoxides upregulated CD86 and/or CD54 on cocultured THP-1 cells in a concentration-dependent manner. The results are comparable with their sensitization potency ranking in predictive animal models. CONCLUSIONS: For the first time, the human sensitization potential and potency of several hydroperoxides were determined by the use of human cells and the COCAT method.

Deciphering miRNAs' Action through miRNA Editing.

MicroRNAs (miRNAs) are small non-coding RNAs with the capability of modulating gene expression at the post-transcriptional level either by inhibiting messenger RNA (mRNA) translation or by promoting mRNA degradation. The outcome of a myriad of physiological processes and pathologies, including cancer, cardiovascular and metabolic diseases, relies highly on miRNAs. However, deciphering the precise roles of specific miRNAs in these pathophysiological contexts is challenging due to the high levels of complexity of their actions. Indeed, regulation of mRNA expression by miRNAs is frequently cell/organ specific; highly dependent on the stress and metabolic status of the organism; and often poorly correlated with miRNA expression levels. Such biological features of miRNAs suggest that various regulatory mechanisms control not only their expression, but also their activity and/or bioavailability. Several mechanisms have been described to modulate miRNA action, including genetic polymorphisms, methylation of miRNA promoters, asymmetric miRNA strand selection, interactions with RNA-binding proteins (RBPs) or other coding/non-coding RNAs. Moreover, nucleotide modifications (A-to-I or C-to-U) within the miRNA sequences at different stages of their maturation are also critical for their functionality. This regulatory mechanism called "RNA editing" involves specific enzymes of the adenosine/cytidine deaminase family, which trigger single nucleotide changes in primary miRNAs. These nucleotide modifications greatly influence a miRNA's stability, maturation and activity by changing its specificity towards target mRNAs. Understanding how editing events impact miRNA's ability to regulate stress responses in cells and organs, or the development of specific pathologies, e.g., metabolic diseases or cancer, should not only deepen our knowledge of molecular mechanisms underlying complex diseases, but can also facilitate the design of new therapeutic approaches based on miRNA targeting. Herein, we will discuss the current knowledge on miRNA editing and how this mechanism regulates miRNA biogenesis and activity.

High Rate of Association of 16S rRNA Methylases and Carbapenemases in Enterobacteriaceae Recovered from Hospitalized Children in Angola.

Acquired 16S rRNA methylases (RMTases) conferring pan-drug resistance to aminoglycosides were searched among enterobacterial isolates recovered in Angola. A total of 36 hospitalized children were screened for rectal colonization using the Superaminoglycoside selective medium. Twenty-two pan-aminoglycoside-resistant enterobacterial isolates were recovered, all of which produced RMTases, i.e., RmtB, ArmA, and RmtC. Highly diverse genetic backgrounds were identified for Escherichia coli and Klebsiella pneumoniae isolates, most of which coproduced carbapenemases NDM-1 or NDM-5, respectively.

Screening and Characterization of Multidrug-Resistant Gram-Negative Bacteria from a Remote African Area, São Tomé and Príncipe.

The occurrence of resistance to last-resort antibiotics was evaluated among Enterobacteriaceae isolates recovered from hospitalized children in a remote African archipelago, São Tomé and Príncipe, where there is limited access to those antibiotics. Fifty patients were screened for colonization by carbapenem-, pan-aminoglycoside-, or polymyxin-resistant Enterobacteriaceae A total of 36 isolates (including 30 Escherichia coli and 4 Klebsiella pneumoniae) were recovered from 23 patients, including 26 isolates harboring the blaOXA-181 carbapenemase gene, a single isolate harboring the 16S rRNA methylase gene rmtB encoding pan-resistance to aminoglycosides, and 8 isolates coharboring both genes. A single isolate possessed the plasmid-borne colistin resistance gene mcr-1 A high clonal relationship was found for OXA-181-producing E. coli (4 clones), and conversely, three of the four OXA-181-producing K. pneumoniae isolates were clonally unrelated. This study overall showed a high prevalence of resistance to last-resort antibiotics in this country, where no epidemiological data were previously available.

High Rate of MCR-1-Producing Escherichia coli and Klebsiella pneumoniae among Pigs, Portugal.

The mcr-1 (mobile colistin resistance 1) gene, which encodes phosphoethanolamine transferase, has been recently identified as a source of acquired resistance to polymyxins in Escherichia coli. Using the SuperPolymyxin selective medium, we prospectively screened 100 pigs at 2 farms in Portugal for polymyxin-resistant Enterobacteriaceae and recovered 98 plasmid-mediated MCR-1-producing isolates. Most isolates corresponded to nonclonally related E. coli belonging to many sequence types; we also found 2 Klebsiella pneumoniae sequence types. The mcr-1 gene was carried on IncHI2 or IncP plasmid backbones. Our finding of a high rate of MCR-1 producers on 2 pig farms in Portugal highlights the diffusion of that colistin-resistance determinant at the farm level. The fact that the pigs received colistin as metaphylaxis in their feed during the 6 weeks before sampling suggests selective pressure.