结核分枝杆菌/利福平耐药实时荧光定量核酸扩增检测技术对肺外结核性脓肿的诊断价值分析

摘要 目的：探讨结核分枝杆菌/利福平耐药实时荧光定量核酸扩增检测技术（Xpert MTB/RIF）对肺外结核性脓肿的诊断价值。方法：收集2020年1月至2021年12月无锡市第五人民医院住院的122例高度疑似肺外结核性脓肿患者为研究对象,在超声引导下对脓肿病灶进行针吸穿刺活检,脓液标本分别进行Xpert MTB/RIF检测、结核杆菌脱氧核糖核酸（TB-DNA）检测、MGIT 960培养以及涂片抗酸染色。以临床综合诊断作为参考标准,比较Xpert MTB/RIF检测、TB-DNA检测、MGIT 960培养以及涂片抗酸染色四种方法对肺外结核性脓肿的诊断效能。对比Xpert MTB/RIF检测和MGIT 960药敏试验对利福平的耐药性。观察各类肺外结核性脓肿患者的诊断延迟时间。结果：122例疑似患者中,最终确诊肺外结核性脓肿患者73例,非结核性脓肿者49例。Xpert MTB/RIF检测、MGIT 960培养、TB-DNA检测以及涂片抗酸染色四种方法在肺外结核性脓肿标本中的阳性检出率结果分别为89.04%、20.55%、58.90%、36.99%,四种方法的阳性检出率整体比较差异有统计学意义（P<0.01）,Xpert MTB/RIF检测的阳性检出率明显高于MGIT 960培养、TB-DNA检测以及涂片抗酸染色法,差异均有统计学意义（P<0.05）。以临床综合诊断作为参考标准,Xpert MTB/RIF检测诊断肺外结核性脓肿者的临床诊断价值最高,其敏感度、特异度、阳性预测值、阴性预测值分别为89.04%、100.00%、100.00%、85.96%。Xpert MTB/RIF检测与MGIT 960药敏试验对利福平耐药率之间差异无统计学意义（P>0.05）。肺外结核性脓肿诊断存在明显延迟,尤其以关节结核性脓肿诊断延迟时间最长,平均为103.5天;但在结核性脓胸患者中诊断延迟时间最短,平均为7.6天。结论：与MGIT 960培养、TB-DNA检测以及涂片抗酸染色比较,Xpert MTB/RIF在肺外结核性脓肿中的阳性检出率较高,临床诊断价值最佳,表明其可用作为疑似结核性脓肿患者的快速诊断工具,同时在结核耐药性方面亦可以做到快速筛查。     

A pilot study to assess the effect of acute exercise on brain glutathione

The brain is highly susceptible to oxidative stress due to its high metabolic demand. Increased oxidative stress and depletion of glutathione (GSH) are observed with aging and many neurological diseases. Exercise training has the potential to reduce oxidative stress in the brain. In this study, nine healthy sedentary males (aged 25?±?4 years) undertook a bout of continuous moderate intensity exercise and a high-intensity interval (HII) exercise bout on separate days. GSH concentration in the anterior cingulate was assessed by magnetic resonance spectroscopy (MRS) in four participants, before and after exercise. This was a pilot study to evaluate the ability of the MRS method to detect exercise-induced changes in brain GSH in humans for the first time. MRS is a non-invasive method based on nuclear magnetic resonance, which enables the quantification of metabolites, such as GSH, in the human brain in vivo. To add context to brain GSH data, other markers of oxidative stress were also assessed in the periphery (in blood) at three time points [pre-, immediately post-, and post (～1?hour)-exercise]. Moderate exercise caused a significant decrease in brain GSH from 2.12?±?0.64?mM/kg to 1.26?±?0.36?mM/kg (p?=?.04). Blood GSH levels increased immediately post-HII exercise, 580?±?101?µM to 692?±?102 µM (n?=?9, p?=?.006). The findings from this study show that brain GSH is altered in response to acute moderate exercise, suggesting that exercise may stimulate an adaptive response in the brain. Due to the challenges in MRS methodology, this pilot study should be followed up with a larger exercise intervention trial.     

Metabolic Changes in Rat Brain After Prolonged Ethanol Consumption Measured by 1H and 31P MRS Experiments

SUMMARY 1. In vivo ¹H and ³¹P magnetic resonance spectroscopy techniques were applied to reveal biochemical changes in the rat brain caused by prolonged ethanol consumption.2. Three models of ethanol intoxication were used.3. ¹H MRS showed a significant decrease in the concentration of myo-inositol in the brain of rats fed with 20% ethanol for 8 weeks. This change is consistent with perturbances in astrocytes. On the other hand, N-acetyl aspartate and choline content did not differ from controls.4. ³¹P MRS did not reveal any significant changes in the high-energy phosphates or intracellular free Mg²⁺ content in the brain of rats after 14 weeks of 20% ethanol drinking. The intracellular pH was diminished.5. By means of a ³¹P saturation transfer technique, a significant decrease was observed for the pseudo first-order rate constant k _for of the creatine kinase reaction in the brain of rats administered 30% ethanol for 3 weeks using a gastric tube.6. The ¹H MRS results may indicate that myo-inositol loss, reflecting a disorder in astrocytes, might be one of the first changes associated with alcoholism, which could be detected in the brain by means of in vivo ¹H MRS.7. The results from ³¹P MRS experiments suggest that alcoholism is associated with decreased brain energy metabolism.8. ³¹P saturation transfer, which provides insight into the turnover of high-energy phosphates, could be a more suitable technique for studying the brain energetics in chronic pathological states than conventional ³¹P MRS.     

Detection of excretory <Emphasis Type="Italic">Entamoeba histolytica</Emphasis> DNA in the urine,and detection of <Emphasis Type="Italic">E. histolytica</Emphasis> DNA and lectin antigen in the liver abscess pus for the diagnosis of amoebic liver abscess

Background  

Amoebic liver abscess (ALA) and pyogenic liver abscesses (PLA) appear identical by ultrasound and other imaging techniques. Collection of blood or liver abscess pus for diagnosis of liver abscesses is an invasive procedure, and the procedure requires technical expertise and disposable syringes. Collection of urine is a noninvasive procedure. Therefore, there has been much interest shown towards the use of urine as an alternative clinical specimen for the diagnosis of some parasitic infections. Here, we report for the first time the detection of E. histolytica DNA excreted in the urine for diagnosis of the cases of ALA.     

Correlation between Choline Signal Intensity and Acetylcholine Level in Different Brain Regions of Rat

Acetylcholine is an important excitatory neurotransmitter, which plays a crucial role in synaptic transmission. The level of acetylcholine is decreased in the early stages of Alzheimer disease (AD), the most common neurodegenerative disease. Therefore, measurement of acetylcholine in the brain may help the clinical diagnosis of AD. However, the methods used till now to detect the brain acetylcholine level are invasive, which are neither recommended nor acceptable in the clinic. Acetylcholine is synthesized from choline-containing compounds (Cho), the latter can be estimated by noninvasive proton magnetic resonance spectroscopy (¹H MRS). To explore whether the Cho signal intensity could be used to represent the acetylcholine level in the brain, we employed ¹H MRS to detect the Cho signal, and simultaneously, we also used microdialysis and high-performance liquid chromatography (HPLC) to measure the level of acetylcholine in hippocampus, striatum, frontal cortex, and somatosensory barrel field (S1BF cortex) of rats, respectively. The results showed that the correlations between Cho signal intensity and acetylcholine level in hippocampus, striatum, frontal cortex, and S1BF cortex were, respectively, 0.823 (p = 0.044), 0.851 (p = 0.032), 0.817 (p = 0.047), and 0.822 (p = 0.045). The F-values of the regression model were, respectively, 8.404 (p = 0.044), 10.47 (p = 0.032), 8.000 (p = 0.047), and 8.326 (p = 0.045). And the derived regression equations were y = 0.67x + 1.363 (hippocampus), y = 5.398x + 6.684 (striatum), y = 0.656x + 0.564 (frontal cortex), and y = 0.394x + 1.127 (S1BF cortex), respectively (y means acetylcholine, and x means Cho). These data suggest that the Cho signal intensity observed by ¹H MRS may be used as an indicator of acetylcholine level in different brain regions of the rats. X.-C. Wang, X.-X. Du, and Q. Tian equally contributed to the work.     

Selenium enhances the antimutagenic activity of probiotic bacterium Enterococcus faecium M-74

The antibacterial activity of the probiotic bacterium Enterococcus faecium M-74 was assessed on De Man–Rogosa–Sharpe (MRS), Todd–Hewitt (T–H), M17 (M-17) and brain heart infusion (BHI) media with sodium selenite pentahydrate (+Se) and without sodium selenite pentahydrate (–Se) under aerobic or anaerobic conditions against nine bacterial pathogens. The highest antibacterial activity was found to be in the MRS medium under anaerobic conditions. There were no differences in the antibacterial activity between MRS(+Se) and MRS(–Se) media. The antimutagenic activity of MRS(+Se) and MRS(–Se) extracts after culture with E. faecium M-74 as well as of live and killed cells of E. faecium M-74 grown in the presence or absence of Se against the genotoxicity of ofloxacin (OFL) and acridine orange (AO) was determined in the Euglena gracilis assay. The MRS(+Se) extracts showed a significantly higher activity in reducing the genotoxicity of OFL and AO than MRS(–Se) extracts. The live cells of the probiotic strain M-74 exhibited higher antimutagenic activity than the killed bacterial cells, but differed depending on the mutagen used. However, the live bacterial cells grown in the presence of Se showed significantly higher antimutagenic activity. These results suggest a potential benefit for the future development of new Se-enriched probiotics exhibiting higher antimutagenic properties.     

Brain abscess due to Nocardia

Cerebral Nocardiosis is a rare disease, usually occurring in immunocompromised hosts. We report here two cases of brain abscess due to Nocardia species-one due to usual N. asteroides and other by uncommon N. caviae. N. asteroides affected the brain in a post renal transplant patient, whereas N. caviae caused infection of brain in an apparently healthy individual. To the best of our knowledge, all the previous cases of brain abscess due to Nocardia caviae have been reported in compromised hosts. Agar dilution antimicrobial testing showed relatively higher resistant pattern in N. asteroides. In spite of antimicrobial therapy, both the patients succumbed, one within 4 days and other after an initial improvement for four weeks due to drainage of abscess.The technical assistance of Mr. R.K. Sapra and Mr. Pawan Kumar is greatfully acknowledged.     

Diurnal rhythmic expression of the rhythm-related genes, <Emphasis Type="Italic">rPeriod1, rPeriod2,</Emphasis> and <Emphasis Type="Italic"> rClock</Emphasis>, in the rat brain

High densities of the mRNA of three rhythm-related genes, rPeriod1 (rPer1), rPer2, and rClock, which share high homology in Drosophila and mammals, are found in the rat hypothalamic suprachiasmatic nucleus (SCN). The SCN, however, is not the only brain region that expresses these genes. To understand the possible physiological roles of these rhythm-related genes, we examined expression of these genes in different brain regions at various time points in male Sprague--Dawley rats. Using semi quantitativein situ hybridization with ³⁵S-riboprobes to evaluate mRNA levels, the diurnal rhythmicity of rPer1, and rPer2 mRNA levels was found in the SCN, arcuate nucleus, and median eminence/pars tuberalis. Expression patterns of mRNA for rPer1 and rPer2, however, were not similar in these brain regions. The rhythmicity in these brain regions was specific, because it was not observed in the cerebellum or hippocampus. Moreover, diurnal changes in rClock mRNA expression were not detected in any of the brain regions examined. These findings suggest that the different expression patterns observed for rPer1, rPer2, and rClock mRNAs may be attributed to their different physiological roles in these brain regions, and support previous work indicating that circadian rhythms in the brain are widespread.     

Size advantage for male function and size‐dependent sex allocation in Ambrosia artemisiifolia,a wind‐pollinated plant

In wind‐pollinated plants, male‐biased sex allocation is often positively associated with plant size and height. However, effects of size (biomass or reproductive investment) and height were not separated in most previous studies. Here, using experimental populations of monoecious plants, Ambrosia altemisiifolia, we examined (1) how male and female reproductive investments (MRI and FRI) change with biomass and height, (2) how MRI and height affect male reproductive success (MRS) and pollen dispersal, and (3) how height affects seed production. Pollen dispersal kernel and selection gradients on MRS were estimated by 2,102 seeds using six microsatellite markers. First, MRI increased with height, but FRI did not, suggesting that sex allocation is more male‐biased with increasing plant height. On the other hand, both MRI and FRI increased with biomass but often more greatly for FRI, and consequently, sex allocation was often female‐biased with biomass. Second, MRS increased with both height and MRI, the latter having the same or larger effect on MRS. Estimated pollen dispersal kernel was fat‐tailed, with the maximum distance between mates tending to increase with MRI but not with height. Third, the number of seeds did not increase with height. Those findings showed that the male‐biased sex allocation in taller plants of A. artemisiifolia is explained by a direct effect of height on MRS.     

Enhancement of Green Gram Nodulation and Growth by Bacillus Species

Rhizobacteria belonging to Bacillus sp. were isolated from the rhizosphere of green gram (Vigna radiata). Seed inoculation with the rhizobacteria showed stunting effect on root growth whereas four Bacillus strains caused stimulation of shoot growth at both 4 and 7 d of observations. Coinoculation of some Bacillus strains with effective Bradyrhizobium strain S24 resulted in enhanced nodulation and plant growth of green gram. The shoot dry mass (ratio to uninoculated control) varied from 1.32 to 6.33 at day 30 and from 1.28 to 3.55 at day 40 of plant growth. Nodule promoting effect after 40 d of plant growth was observed with majority of Bacillus strains except for MRS9 and MRS26. Maximum gains in nodulation, nitrogenase activity and plant growth were observed with Bacillus strains MRS12, MRS18, MRS22 and MRS27 after 40 d of plant growth, suggesting the usefulness of introduced rhizobacteria in improving crop productivity.     

Altered neurochemical profile in the McGill‐R‐Thy1‐APP rat model of Alzheimer's disease: a longitudinal in vivo 1H MRS study

We investigated metabolite levels during the progression of pathology in McGill‐R‐Thy1‐APP rats, a transgenic animal model of Alzheimer's disease, and in healthy age‐matched controls. Rats were subjected to in vivo ¹H magnetic resonance spectroscopy (MRS) of the dorsal hippocampus at age 3, 9 and 12 months and of frontal cortex at 9 and 12 months. At 3 months, a stage in which only Aβ oligomers are present, lower glutamate, myo‐inositol and total choline content were apparent in McGill‐R‐Thy1‐APP rats. At age 9 months, lower levels of glutamate, GABA, N‐acetylaspartate and total choline and elevated myo‐inositol and taurine were found in dorsal hippocampus, whereas lower levels of glutamate, GABA, glutamine and N‐acetylaspartate were found in frontal cortex. At age 12 months, only the taurine level was significantly different in dorsal hippocampus, whereas taurine, myo‐inositol, N‐acetylaspartate and total creatine levels were significantly higher in frontal cortex. McGill‐R‐Thy1‐APP rats did not show the same changes in metabolite levels with age as displayed in the controls, and overall, prominent and complex metabolite differences were evident in this transgenic rat model of Alzheimer's disease. The findings also demonstrate that in vivo ¹H MRS is a powerful tool to investigate disease‐related metabolite changes in the brain.     

Longitudinal in vivo developmental changes of metabolites in the hippocampus of Fmr1 knockout mice

Fragile X syndrome (FXS) is the most common form of inherited mental retardation and is studied in the Fmr1 knockout (KO) mouse, which models both the anatomical and behavioral changes observed in FXS patients. In vitro studies have shown many alterations in synaptic plasticity and increased density of immature dendritic spines in the hippocampus, a region involved in learning and memory. In this study, magnetic resonance imaging (MRI) and ¹H magnetic resonance spectroscopy (MRS) were used to determine in vivo longitudinal changes in volume and metabolites in the hippocampus during the critical period of early myelination and synaptogenesis at post‐natal days (PND) 18, 21, and 30 in Fmr1 KO mice compared with wild‐type (WT) controls. MRI demonstrated an increase in volume of the hippocampus in the Fmr1 KO mouse compared with controls. MRS revealed significant developmental changes in the ratios of hippocampal metabolites N‐acetylaspartate (NAA), myo‐inositol (Ins), and taurine to total creatine (tCr) in Fmr1 KO mice compared with WT controls. Ins was decreased at PND 30, and taurine was increased at all ages studied in Fmr1 KO mice compared with controls. An imbalance of brain metabolites in the hippocampus of Fmr1 KO mice during the critical developmental period of synaptogenesis and early myelination could have long‐lasting effects that adversely affect brain development and contribute to ongoing alterations in brain function.     

Addition of a surfactant to tryptic soy broth allows growth of a lactic acid bacteria food antimicrobial, Escherichia coli O157:H7, and Salmonella enterica

Aims: This study aimed to determine the survival and growth of Escherichia coli O157:H7 and Salmonella enterica subsp. enterica in a medium supporting the growth of a Lactic Acid Bacteria (LAB) food antimicrobial culture. Methods and Results: Foodborne pathogens and LAB were cultured individually in tryptic soy broth (TSB), tryptic soy broth supplemented with one g l^?1 Tween 80^® (TSB‐T80), and de Man, Rogosa and Sharpe (MRS) broth. Growth of E. coli O157:H7 and Salmonella was similar in TSB and TSB‐T80 but was significantly less in MRS. Conversely, LAB growth was similar in MRS and TSB‐T80 but was significantly less in TSB. Conclusions: Supplementation of TSB with Tween 80^® allows growth of LAB to levels similar to that observed with MRS but does not inhibit the growth of E. coli O157:H7 and Salmonella. We present the formulation of a medium useful in studies useful for evaluating competitive inhibition of foodborne pathogens by LAB in vitro. Significance and Impact of the Study: This study reports the utility of TSB‐T80 for the completion of in vitro competitive inhibition assays incorporating a Lactic Acid Bacteria food safety culture.     

Pigment Diverse Mutants of Pseudomonas sp.: Inhibition of Fungal Growth and Stimulation of Growth of Cicer arietinum

A Pseudomonas strain MRS16 inhibited growth of different pathogenic fungi (Aspergillus sp., Fusarium oxysporum, Pythium aphanidermatum and Rhizoctonia solani) in vitro. Larger inhibition zones were obtained on nutrient agar and King's B media compared to potato dextrose agar and pigment production media. Mutants altered in production of fluorescent pigment were derived by nitrosoguanidine mutagenesis. The pigment overproducer mutant MRS16M-1 was more inhibitory whereas nonproducer mutant MRS16M-5 was less inhibitory than parent strain on nutrient agar medium. Addition of iron (100 µM FeCl₃) in the medium decreased inhibition of fungal growth, suggesting the involvement of siderophores and other antifungal secondary metabolites. Seed bacterization of two cultivars of chickpea (Cicer arietinum cvs. H8618 and C235) differing in susceptibility to wilt caused initial root and shoot stunting at 5 d of growth followed by proliferation of secondary root growth at 10 d. Coinoculation of chickpea with Pseudomonas strain MRS16 or mutants and Rhizobium sp. Cicer strain Ca181 enhanced nodulation, nitrogen fixation and plant dry mass as compared to single inoculation with Rhizobium strain under sterile conditions.     

Usefulness of Multi-Parametric MRI for the Investigation of Posterior Cortical Atrophy

Background

Posterior Cortical Atrophy (PCA) is a neurodegenerative disease characterized by a progressive decline in selective cognitive functions anatomically referred to occipital, parietal and temporal brain regions, whose diagnosis is rather challenging for clinicians. The aim of this study was to assess, using quantitative Magnetic Resonance Imaging techniques, the pattern of regional grey matter loss and metabolism in individuals with PCA to improve pathophysiological comprehension and diagnostic confidence.

Methods

We enrolled 5 patients with PCA and 5 matched controls who all underwent magnetic resonance imaging (MRI) and spectroscopy (MRS). Patients also underwent neuropsychological and cerebrospinal fluid (CSF) assessments. MRI data were used for unbiased assessment of regional grey matter loss in PCA patients compared to controls. MRS data were obtained from a set of brain regions, including the occipital lobe and the centrum semiovale bilaterally, and the posterior and anterior cingulate.

Results

VBM analysis documented the presence of focal brain atrophy in the occipital lobes and in the posterior parietal and temporal lobes bilaterally but more pronounced on the right hemisphere. MRS revealed, in the occipital lobes and in the posterior cingulate cortex of PCA patients, reduced levels of N-Acetyl Aspartate (NAA, a marker of neurodegeneration) and increased levels of Myo-Inositol (Ins, a glial marker), with no hemispheric lateralization.

Conclusion

The bilateral but asymmetric pattern of regional grey matter loss is consistent with patients’ clinical and neuropsychological features and with previous literature. The MRS findings reveal different stages of neurodegeneration (neuronal loss; gliosis), which coexist and likely precede the occurrence of brain tissue loss, and might represent early biomarkers. In conclusion, this study indicates the potential usefulness of a multi-parametric MRI approach for an early diagnosis and staging of patients with PCA.     

A soluble 12-kDa protein of the mitochondrial intermembrane space, Mrs11p, is essential for mitochondrial biogenesis and viability of yeast cells

We have isolated an essential yeast gene, termed MRS11, which codes for a soluble protein of the mitochondrial intermembrane space. Interestingly, this new gene shares many similarities with the previously characterized MRS5 gene: when expressed from a multicopy plasmid, MRS11 like MRS5 restores respiration competence to yeast strains defective in the splicing of mitochondrial group II introns. Both genes are essential for viability of yeast cells, as the disruption of either of them is lethal. The proteins encoded by MRS5 and MRS11, which display 35%, sequence identity are both located in the mitochondrial intermembrane space. Depletion of Mrs11p results in a phenotype similar to that observed in Mrs5p-depleted cells: accumulation of the precursor form of mitochondrial hsp60, inability to form spectrophotometrically detectable amounts of cytochromes and changes in the mitochondrial morphology. Although similar in sequence and function, Mrs5p and Mrs11p are not functionally equivalent and neither can substitute for the other, even when overexpressed. Taken together, our data suggest a cooperative mode of action of Mrs11p and Mrs5p in mitochondrial protein import or other related essential mitochondrial processes. Received: 14 January 1997 / Accepted: 18 March 1997     

Infecc Ón Humana PorNocardia Asteroides,En México

Summary Although the existence ofNocardia asteroides as a human pathogen in Mexico has been known for several years, up to now there are only few reports in our country concerning the isolation of this microorganism both as a saprophyte as well as human or animal pathogen. This fact is more interesting when compared with the high incidence ofN. brasiliensis, causal agent of actinomycotic mycetoma, the most frequently observed deep mycosis in Mexico.In this paper, the isolation of eigth strains ofN. asteroides from clinical specimens is reported. Five strains were isolated from sputa, one from a fistulous lesion of the scrotum, one from a brain abscess and one more from a foot mycetoma.One of the strains isolated from sputum was in a case of pulmonary nocardiasis; another of these strains was isolated from a patient with coexistent pulmonary tuberculosis and nocardiasis. With the last three strains isolated from sputa, it was not possible to establish any correlation between the isolations and the clinical and radiological findings of the patients; two of the patients had pulmonary tuberculosis and the isolation ofN. asteroides was achieved only in one occasion in each case, with scant growth, and observed in routine cultures made for tubercle bacilli. The last strain was isolated from the sputum of a patient with chronic bronchitis. Some comments are made to the possibility that these three last isolations merely represent a saprophytic phase of the fungus.Some clinical and other features are discussed concerning the other three cases of scrotal fistula, brain abscess and mycetoma produced byN. asteroides.     

Pulsed-Field Gel Electrophoresis Is More Discriminating Than Multilocus Enzyme Electrophoresis and Random Amplified Polymorphic DNA Analysis for Typing Pyogenic Streptococci

The SmaI restriction endonuclease digestion patterns of chromosomal DNAs from 99 pyogenic streptococci belonging to Lancefield group A (41 Streptococcus pyogenes), group C (seven S. dysgalactiae, 11 \QS. equisimilis\W, three S. equi, eight S. zooepidemicus) and group G (25 human group G Streptococcus, four S. canis) were analyzed by pulsed-field gel electrophoresis (PFGE), and the results were compared with those previously obtained by multilocus enzyme electrophoresis (MLEE) and random amplified polymorphic DNA analysis (RAPD). PFGE revealed 93 distinct types among the 99 strains, and no patterns were common to strains of different species. The discriminatory power of PFGE was greater than that of MLEE and RAPD for groups A and G streptococci. The polymorphism among group C streptococci was similar with the three techniques. PFGE is, therefore, the most efficacious method for epidemiological typing of pyogenic streptococci. Received: 31 July 1996 / Accepted: 17 August 1996     

Isolation and identification of lactic acid bacteria from sediments of a coastal marsh using a differential selective medium

Aims:  To identify lactic acid bacteria (LAB) colonies isolated from sediments of a coastal marsh by the reduction of 2,3,5‐triphenyltetrazolium chloride (TTC) in MRS medium. Methods and Results:  Single colonies isolated from sediments of a coastal marsh by enrichment in MRS broth were selected from MRS‐TTC plates and classified according to colony phenotype based on TTC reduction. A total of 37 colonies grouped in seven different phenotypes were identified by analysis of its 16S ribosomal gene sequence. Most isolates belonged to the Firmicutes phylum, mainly to orders Bacillales and Lactobacillales. LAB were represented by 20 isolates, 15 of which belong to the genus Weissella. Conclusions:  Enrichment in MRS was highly selective for the isolation of bacteria belonging to phylum Firmicutes. Several different phenotypes were developed by LAB and must be considered during LAB isolation based on TTC reduction. Significance and Impact of the Study:  To our knowledge, this is the first study aimed at determining a relationship between colony phenotype from TTC reduction and a partial identification of isolates based on 16S ribosomal gene sequence similarities. Besides, this is the first report of isolation of W. cibaria from environmental samples.