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Journal of Medical Microbiology logo - Volume 70, Issue 6, 2021

Volume 70, Issue 6

Volume 70, Issue 6, 2021

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  • Reviews

      • The microbiome of the nasopharynx

        https://doi.org/10.1099/jmm.0.001368

        The nasopharyngeal microbiome is a dynamic microbial interface of the aerodigestive tract, and a diagnostic window in the fight against respiratory infections and antimicrobial resistance. As its constituent bacteria, viruses and mycobacteria become better understood and sampling accuracy improves, diagnostics of the nasopharynx could guide more personalized care of infections of surrounding areas including the lungs, ears and sinuses. This review will summarize the current literature from a clinical perspective and highlight its growing importance in diagnostics and infectious disease management.

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  • Antimicrobial Resistance

      • Characterization of a carbapenem-resistant coharbouring and genes

        https://doi.org/10.1099/jmm.0.001364

        Members of the genus are facultative anaerobic Gram-negative bacilli belonging to the [Janda 1994; 32(8):1850–1854; Arens 1997;3(1):53–57]. Formerly, were occasionally reported as nosocomial pathogens with low virulence [Pepperell 2002;46(11):3555–60]. Now, they are consistently reported to cause nosocomial infections of the urinary tract, respiratory tract, bone, peritoneum, endocardium, meninges, intestines, bloodstream and central nervous system. Among species, the most common isolates are and , while has seldom been isolated [Janda 1994; 32(8):1850–1854; Marak 2017;49(7):532–9]. Further, spp. are usually susceptible to carbapenems, aminoglycosides, tetracyclines and colistin [Marak 2017;49(7):532–9].

        As is rare, only one clinical isolate, coharbouring carbapenem resistance gene and quinolone resistance gene , has been reported.

        To characterize a carbapenem-resistant strain from PR China coharbouring and .

        Three hundred and forty nonrepetitive carbapenem-resistant (CRE) strains were collected during 2011–2018. A carbapenem-resistant strain was detected and confirmed using a VITEK mass spectrometry-based microbial identification system and 16S rRNA sequencing. Minimum inhibitory concentrations (MICs) for clinical antimicrobials were obtained by the broth microdilution method. Whole-genome sequencing (WGS) was performed for antibiotic resistance gene analysis, and a phylogenetic tree of strains was constructed using the Bacterial Pan Genome Analysis (BPGA) tool. The transferability of the resistance plasmid was verified by conjugal transfer.

        A rare carbapenem-resistant strain (CA71) was recovered from a patient with cerebral obstruction and the sequences of 16S rRNA gene shared more than 99 % similarity with CITRO86, FDAARGOS 165. CA71 is resistant to β-lactam, quinolone and aminoglycoside antibiotics, and even imipenem and meropenem (MICs of 2 and 4 mg l respectively), and is only sensitive to polymyxin B and tigecycline. Six antibiotic resistance genes were detected via WGS, including the β-lactam genes , and , the quinolone gene , and the aminoglycoside genes . Interestingly, and coexist on an IncN1-type plasmid (pCA71-IMP) and successfully transferred to J53 via conjugal transfer. Phylogenetic analysis showed that CA71 is most similar to strain CJ25 and belongs to the same evolutionary cluster along with seven other strains.

        To the best of our knowledge, this is the first report of a carbapenem-resistant isolate coharbouring and .

    • Detection and partial characterization of extracellular inducers of persistence in and

      https://doi.org/10.1099/jmm.0.001392

      This study describes the identification and partial characterization of persistence-inducing factors (PIFs) from staphylococci.

      Increases in persisters during mid-log phase growth indicate that quorum-sensing factors might be produced by staphylococci.

      To identify and partially characterize PIFs from RP62A and SH1000.

      Others have demonstrated a significant increase in persister numbers during mid-log phase. Inducers of this mid-log increase have yet to be identified in staphylococci. Optical density at 600 nm (OD) was used instead of time to determine when persister numbers increased during logarithmic growth. Concentrated culture filtrates (CCFs) from and were obtained at various ODs and following incubation at 16 h. The CCFs were used to develop a PIF assay. The PIF assay was used to partially characterize PIF from and for sizing of PIF activity, temperature and protease sensitivity and inter-species communications.

      The optimal ODs for and PIF assays were 2.0 and 0.5, respectively. The highest PIF activity for both species was from CCF following incubation overnight (16 h). ’ PIF activity was decreased by storage at 4 C but not at 20 C (16 h), 37 C (1 h) or 100 C (15 min). ’ PIF activity was decreased following storage at 4 C (2 weeks) and after boiling at 100 C for 5 min but not after incubation at 37 C (1 h). PIF activity from both species went through a 3000 molecular weight cutoff ultrafilter. Proteinase K treatment of PIF decreased activity but did not decrease the PIF activity of . PIF from did not increase persisters when used to treat cells and nor did PIF from increase persisters when used to treat cells.

      Attempts to discover PIFs for staphylococci were unsuccessful due to the time-based means used to identify mid-log. Both staphylococcal species produce extracellular, low-molecular-weight inducers of persistence when assayed using an OD -based PIF assay.

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  • One Health ‒ Emerging, Zoonotic and Environmental Diseases

      • Leishmanicidal potentials of extract and its fractions on in a murine model: parasite burden, gene expression, and histopathological profile

        https://doi.org/10.1099/jmm.0.001333

        Leishmaniasis is a neglected tropical and subtropical disease caused by over 20 protozoan species.

        Treatment of this complex disease with traditional synthetic drugs is a major challenge worldwide. Natural constituents are unique candidates for future therapeutic development.

        This study aimed to assess the anti-leishmanial effect of the extract, and its fractions compared to the standard drug (Glucantime, MA) in a murine model and explore the mechanism of action.

        Footpads of BALB/c mice were infected with stationary phase promastigotes and treated topically and intraperitoneally with extract, its fractions, or Glucantime, 4 weeks post-infection. The extract and fractions were prepared using the Soxhlet apparatus with chloroform followed by the column procedure.

        The crude extract significantly decreased the footpad parasite load and lesion size compared to the untreated control group (<0.05), as revealed by dilution assay, quantitative real-time PCR, and histopathological analyses. The primary mode of action involved an immunomodulatory role towards the Th1 response in the up-regulation of IFN-γ and IL-12 and the suppression of IL-10 gene expression profiling against cutaneous leishmaniasis caused by .

        This finding suggests that the extract possesses multiple combinatory effects of diverse bioactive phytochemical compositions that exert its mechanisms of action through agonistic-synergistic interactions. The topical extract formulation could be a suitable and unique candidate for future investigation and pharmacological development. Further studies are crucial to evaluate the therapeutic potentials of the extract alone and in combination with conventional drugs using clinical settings.

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  • Pathogenesis, Virulence and Host Response

      • The role of lipid droplets in microbial pathogenesis

        https://doi.org/10.1099/jmm.0.001383

        The nonpolar lipids present in cells are mainly triacylglycerols and steryl esters. When cells are provided with an abundance of nutrients, these storage lipids accumulate. As large quantities of nonpolar lipids cannot be integrated into membranes, they are isolated from the cytosolic environment in lipid droplets. As specialized, inducible cytoplasmic organelles, lipid droplets have functions beyond the regulation of lipid metabolism, in cell signalling and activation, membrane trafficking and control of inflammatory mediator synthesis and secretion. Pathogens, including fungi, viruses, parasites, or intracellular bacteria can induce and may benefit from lipid droplets in infected cells. Here we review biogenesis of lipid droplets as well as the role of lipid droplets in the pathogenesis of selected viruses, bacteria, protists and yeasts.

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