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The RNA binding protein Hfq has a central role in the post-transcription control of gene expression in many bacteria. Numerous studies have mapped the transcriptome-wide Hfq-mediated RNA-RNA interactions in growing bacteria or bacteria that have entered short-term growth-arrest. To what extent post-transcriptional regulation underpins gene expression in growth-arrested bacteria remains unknown. Here, we used nitrogen (N) starvation as a model to study the Hfq-mediated RNA interactome as Escherichia coli enter, experience, and exit long-term growth arrest. We observe that the Hfq-mediated RNA interactome undergoes extensive changes during N starvation, with the conserved SdsR sRNA making the most interactions with different mRNA targets exclusively in long-term N-starved E. coli. Taking a proteomics approach, we reveal that in growth-arrested cells SdsR influences gene expression far beyond its direct mRNA targets. We demonstrate that the absence of SdsR significantly compromises the ability of the mutant bacteria to recover growth competitively from the long-term N-starved state and uncover a conserved post-transcriptional regulatory axis which underpins this process., (© The Author(s) 2023. Published by Oxford University Press on behalf of Nucleic Acids Research.)

Small noncoding RNAs (sRNAs) from mRNA 3' UTRs seem to present a previously unrecognized layer of bacterial post-transcriptional control whereby mRNAs influence each other's expression, independently of transcriptional control. Studies in Escherichia coli and Salmonella enterica showed that such sRNAs are natural products of RNase E-mediated mRNA decay and associate with major RNA-binding proteins (RBPs) such as Hfq and ProQ. If so, there must be additional sRNAs from mRNAs that accumulate only under specific physiological conditions. We test this prediction by characterizing candidate NarS that represents the 3' UTR of nitrate transporter NarK whose gene is silent during standard aerobic growth. We find that NarS acts by Hfq-dependent base pairing to repress the synthesis of the nitrite transporter, NirC, resulting in mRNA cross-regulation of nitrate and nitrite transporter genes. Interestingly, the NarS-mediated repression selectively targets the nirC cistron of the long nirBDC-cysG operon, an observation that we rationalize as a mechanism to protect the bacterial cytoplasm from excessive nitrite toxicity during anaerobic respiration with abundant nitrate. Our successful functional assignment of a 3' UTR sRNA from a non-standard growth condition supports the notion that mRNA crossregulation is more pervasive than currently appreciated., (© The Author(s) 2019. Published by Oxford University Press on behalf of Nucleic Acids Research.)

Global RNA profiling studies in bacteria have predicted the existence of many of small noncoding RNAs (sRNAs) that are processed off mRNA 3' ends to regulate other mRNAs via the RNA chaperones Hfq and ProQ. Here, we present targets of SdhX (RybD), an Hfq-dependent sRNA that is generated by RNase E mediated 3' processing of the ∼10 000-nt mRNA of the TCA cycle operon sdhCDAB-sucABCD in enteric bacteria. An in silico search predicted ackA mRNA, which encodes acetate kinase, as a conserved primary target of SdhX. Through base pairing, SdhX represses AckA synthesis during growth of Salmonella on acetate. Repression can be achieved by a naturally occurring 38-nucleotide SdhX variant, revealing the shortest functional Hfq-associated sRNA yet. Salmonella SdhX also targets the mRNAs of fumB (anaerobic fumarase) and yfbV, a gene of unknown function adjacent to ackA. Instead, through a slightly different seed sequence, SdhX can repress other targets in Escherichia coli, namely katG (catalase) and fdoG (aerobic formate dehydrogenase). This study illustrates how a key operon from central metabolism is functionally connected to other metabolic pathways through a 3' appended sRNA, and supports the notion that mRNA 3'UTRs are a playground for the evolution of regulatory RNA networks in bacteria., (© The Author(s) 2018. Published by Oxford University Press on behalf of Nucleic Acids Research.)

Pregnant women with urinary schistosomiasis should be treated, but screening is not implemented in migrants. We report herein a case of a migrant diagnosed late into pregnancy, after diagnosis was made in her husband. Praziquantel was safe and effective. Schistosomiasis should be considered in pregnant women from endemic countries., (© International Society of Travel Medicine, 2016. Published by Oxford University Press. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.)

The way in which an antibiotic interacts with host defences could influence the clinical outcome of many infectious diseases. The impact of RO 23-9424, a novel dual-action and extended-spectrum antibiotic, was studied on several functions of human polymorphonuclear neutrophils (PMNs). A significant (P < 0.05) increase of the superoxide (O2-) released by phorbol-myristate acetate (PMA) -stimulated PMN (10-100 mg/L) can be observed in the RO 23-9424 pre-treated cells. RO 23-9424, particularly at low dosages, showed an interesting but not statistically significant effect on PMN phagocytosis. Higher dosages of RO 23-9424 (50-200 mg/L) and fleroxacin (20-200 mg/L) significantly reduced PMN chemotaxis. Cytokine production by human monocytes were also evaluated after incubation with the antibiotic (100-200 mg/L) in both basal conditions and in response to endotoxin (lipopolysaccharide, LPS). In the LPS-treated cells, RO 23-9424 (100 mg/L) significantly (P < 0.05) enhanced the tumour necrosis factor-alpha (TNF-alpha) levels, compared with LPS controls after 4 h of incubation. RO 23-9424 (200 mg/L) was able to reduce in a dose-dependent way LPS-induced interleukin-1 beta (IL-1 beta) after 4 and 24 h of incubation. Interleukin-8 (IL-8) release was not significantly changed by RO 23-9424. Cefotaxime (200 mg/L) significantly (P < 0.05) increased the basal levels of IL-1 beta and reduced basal IL-8 concentration after 24 h of incubation. The lower concentration of cefotaxime reduced the LPS-stimulated IL-8 levels. Fleroxacin (100 mg/L) enhanced basal levels of IL-8. The potentiated PMN phagocytosis, the significantly enhanced O2- release by PMA-stimulated PMN and the dimetric changes of TNF-alpha and IL-1 beta appeared peculiar for RO 23-9424 and may have useful therapeutical implications.

Three different tests were performed to investigate the effect of teicoplanin on lipopolysaccharide (LPS). After incubation for 3 h with teicoplanin, LPS from Salmonella minnesota R595 showed reduced reactivity in the metachromatic dimethyl-methylene blue assay and the limulus amoebocyte lysate test. In addition, galactosamine-sensitized mice had an increased survival rate, from 29% to 72%, when teicoplanin was pre-incubated for 3 h with the LPS to be injected intraperitoneally. The results suggest that teicoplanin may have a neutralizing effect on LPS.

This study was undertaken to investigate the efficacy of different beta-lactam antibiotics in the treatment of systemic salmonella infections in the mouse typhoid model. Innately susceptible BALB/c (Itys) and resistant CBA (Ityr) mice were used to investigate the efficacy of one monocyclic (aztreonam) and three bicyclic (ampicillin, cefazolin, ceftazidime) beta-lactam antibiotics in controlling systemic salmonella infections when given for brief or prolonged periods. The present study confirms and amplifies earlier reports on ampicillin therapy, demonstrates marked differences in the efficacy of the different antibiotics and shows that aztreonam is not only very effective but can completely eradicate the salmonellae from the RES when given early in the infection.