Black blow fly (Diptera: Calliphoridae) bacterial symbionts inform oviposition site selection by stable flies (Diptera: Muscidae).

Larval habitats of blood-feeding stable flies, Stomoxys calcitrans (L.) (Diptera: Muscidae), overlap with foraging sites of black blow flies, Phormia regina (Meigen) (Diptera: Calliphoridae). We tested the hypothesis that bacteria in blow fly excreta inform oviposition decisions by female stable flies. In laboratory 2-choice bioassays, we offered gravid female stable flies fabric-covered agar plates as oviposition sites that were kept sterile or inoculated with either a blend of 7 bacterial strains isolated from blow fly excreta (7-isolate-blend) or individual bacterial isolates from that blend. The 7-isolate-blend deterred oviposition by female stable flies, as did either of 2 strains of Morganella morganii subsp. sibonii. Conversely, Exiguobacterium sp. and Serratia marcescens each prompted oviposition by flies. The flies' oviposition decisions appear to be guided by bacteria-derived semiochemicals as the bacteria could not be physically accessed. Oviposition deterrence caused by semiochemicals of the 7-isolate-blend may help stable flies avoid competition with blow flies. The semiochemicals of bioactive bacterial strains could be developed as trap lures to attract and capture flies and deter their oviposition in select larval habitats.

Histamine Production Behaviors of a Psychrotolerant Histamine-Producer, Morganella psychrotolerans, in Various Environmental Conditions.

Histamine food poisoning is a major safety concern related to seafood consumption worldwide. Morganella psychrotolerans is a novel psychrotolerant histamine-producer. In this study, the histamine production behaviors of M. psychrotolerans and two other major histamine-producers, mesophilic Morganella morganii and psychrotrophic Photobacterium phosphoreum, were compared in seafood products, and histamine accumulation by M. psychrotolerans was characterized at various pH and temperature levels in culture broth. The growth of M. psychrotolerans and P. phosphoreum increased similarly at 4 °C in canned tuna, but M. psychrotolerans produced much higher levels of histamine than P. phosphoreum. Histamine accumulation by M. psychrotolerans was induced at lower environmental pH condition at 4 and 20 °C. The optimal temperature and pH for producing histamine by crude histidine decarboxylase of M. psychrotolerans were 30 °C and pH 7, respectively. The activity of the crude HDC extracted from M. psychrotolerans cells at 10 °C retained 45% of the activity at 30 °C. Histidine decarboxylase gene expression of M. psychrotolerans was induced by low pH conditions. These results suggest that M. psychrotolerans are also a very important histamine-producer leading to histamine poisoning associated with seafood below the refrigeration temperature.

Proteae: a reservoir of class 2 integrons?

OBJECTIVES: Our aim was to confirm with a large panel of clinical isolates that class 2 integrons are highly prevalent in Proteae and to analyse their genetic characteristics. METHODS: Proteae (Proteus spp., Morganella spp. and Providencia spp.) isolates were collected from clinical samples during 2013 at Limoges University Hospital, France. The presence of class 1, 2 and 3 integrons was investigated by quantitative PCR. The presence of a stop codon in the intI2 gene was determined by Sanger sequencing. The gene cassette arrays of class 2 integrons were determined by PCR-RFLP and Sanger sequencing or next-generation sequencing when needed. RESULTS: Of the 327 Proteae collected, 103 (31.5%) harboured a class 2 integron and 45 (13.8%) a class 1 integron. No class 3 integrons were detected. One functional IntI2 integrase was detected in a Morganella morganii isolate. Six different gene cassette arrays were detected. Four had already been described in the literature: dfrA1-sat2-aadA1 (72 isolates), dfrA1-catB2-sat2-aadA1 (17), sat2-aadA1 (6) and lnu(F), dfrA1, aadA1 (1). We identified two new gene cassette arrays: (i) a new variant of the dfrA1 gene cassette (one isolate; the one with the functional IntI2); and (ii) the array dfrA1-gcu115-sat2 harbouring the new gcu115 gene cassette with two ORFs encoding proteins of unknown functions (five isolates). CONCLUSIONS: We showed a high frequency of class 2 integrons, as well as a diversity of gene cassette arrays, among Proteae. This work highlights that the Proteae tribe plays an important role as a reservoir of class 2 integrons.

A clinical evaluation of a sensor to detect blockage due to crystalline biofilm formation on indwelling urinary catheters.

OBJECTIVE: To test the performance and acceptability of an early warning sensor to predict encrustation and blockage of long-term indwelling urinary catheters. PATIENTS AND METHODS: In all, 17 long-term indwelling catheter users, 15 'blockers' and two 'non-blockers' (controls) were recruited; 11 participants were followed prospectively until catheter change, three withdrew early and three did not start. Two sensors were placed in series between the catheter and the urine bag at catheter change. The sensor nearest the bag was changed at the same time as the bag change (weekly); the sensor nearest the catheter remained in situ for the duration of the catheter's life. Bacteriology and pH determinations were performed on urine samples at each bag, sensor and catheter change. The colour of the sensors was recorded daily. On removal, each sensor and the catheter were examined for visible evidence of encrustation and blockage. Participants were asked to keep a daily diary to record colour change and any other relevant observations and to complete a psychosocial impact of assistive devices tool at the end of the study. Participants and carers/healthcare professionals (when involved in urine bag or catheter change) were asked to complete a questionnaire about the sensor. RESULTS: Urease-producing bacteria were isolated from seven of the 14 patients (including early withdrawals; P. mirabilis in four, Morganella or Providencia in three). In six of the seven patients the sensors turned blue-black; two of these were early withdrawals, two went to planned catheter change (one of these was recruited as a 'non-blocker') and three had catheter blockage. The number of days of catheterisation before blockage was 22, 23 and 25 days, and the sensor changed colour within 24-48 h after insertion. The urine mean (range) pH of the sensors that turned blue-black was 7.6 (5.5-9.0) and of the sensors that remained yellow 6.1 (5.1-7.5). The sensor was generally well-received and was positive in the psychosocial assessment. CONCLUSIONS: The sensor is a useful indicator of urine pH and of the conditions that lead to catheter blockage. It may be particularly useful for new indwelling catheter users. To be a universally acceptable predictor of catheter blockage, the time from sensor colour change to blockage needs to be reduced.

Spread of carbapenemase-producing Morganella spp from 2013 to 2021: a comparative genomic study.

BACKGROUND: Morganella spp are opportunistic pathogens involved in various infections. Intrinsic resistance to multiple antibiotics (including colistin) combined with the emergence of carbapenemase producers reduces the number of active antimicrobials. The aim of this study was to characterise genetic features related to the spread of carbapenem-resistant Morganella spp. METHODS: This comparative genomic study included extensively drug-resistant Morganella spp isolates collected between Jan 1, 2013, and March 1, 2021, by the French National Reference Center (NRC; n=68) and European antimicrobial resistance reference centres in seven European countries (n=104), as well as one isolate from Canada, two reference strains from the Pasteur Institute collection (Paris, France), and two colistin-susceptible isolates from Bicêtre Hospital (Kremlin-Bicêtre, France). The isolates were characterised by whole-genome sequencing, antimicrobial susceptibility testing, and biochemical tests. Complete genomes from GenBank (n=103) were also included for genomic analysis, including phylogeny and determination of core genomes and resistomes. Genetic distance between different species or subspecies was performed using average nucleotide identity (ANI). Intrinsic resistance mechanisms to polymyxins were investigated by combining genetic analysis with mass spectrometry on lipid A. FINDINGS: Distance analysis by ANI of 275 isolates identified three groups: Morganella psychrotolerans, Morganella morganii subspecies sibonii, and M morganii subspecies morganii, and a core genome maximum likelihood phylogenetic tree showed that the M morganii isolates can be separated into four subpopulations. On the basis of these findings and of phenotypic divergences between isolates, we propose a modified taxonomy for the Morganella genus including four species, Morganella psychrotolerans, Morganella sibonii, Morganella morganii, and a new species represented by a unique environmental isolate. We propose that M morganii include two subspecies: M morganii subspecies morganii (the most prevalent) and M morganii subspecies intermedius. This modified taxonomy was supported by a difference in intrinsic resistance to tetracycline and conservation of metabolic pathways such as trehalose assimilation, both only present in M sibonii. Carbapenemase producers were mostly identified among five high-risk clones of M morganii subspecies morganii. The most prevalent carbapenemase corresponded to NDM-1, followed by KPC-2, and OXA-48. A cefepime-zidebactam combination was the most potent antimicrobial against the 172 extensively drug-resistant Morganella spp isolates in our collection from different European countries, which includes metallo-ß-lactamase producers. Lipid A analysis showed that the intrinsic resistance to colistin was associated with the presence of L-ARA4N on lipid A. INTERPRETATION: This global characterisation of, to our knowledge, the widest collection of extensively drug-resistant Morganella spp highlights the need to clarify the taxonomy and decipher intrinsic resistance mechanisms, and paves the way for further genomic comparisons. FUNDING: None.

Pathometagenomics reveals susceptibility to intestinal infection by Morganella to be mediated by the blood group-related B4galnt2 gene in wild mice.

Infectious disease is widely considered to be a major driver of evolution. A preponderance of signatures of balancing selection at blood group-related genes is thought to be driven by inherent trade-offs in susceptibility to disease. B4galnt2 is subject to long-term balancing selection in house mice, where two divergent allele classes direct alternative tissue-specific expression of a glycosyltransferase in the intestine versus blood vessels. The blood vessel allele class leads to prolonged bleeding times similar to von Willebrand disease in humans, yet has been maintained for millions of years. Based on in vivo functional studies in inbred lab strains, it is hypothesized that the cost of prolonged bleeding times may be offset by an evolutionary trade-off involving susceptibility to a yet unknown pathogen(s). To identify candidate pathogens for which resistance could be mediated by B4galnt2 genotype, we here employed a novel "pathometagenomic" approach in a wild mouse population, which combines bacterial 16S rRNA gene-based community profiling with histopathology of gut tissue. Through subsequent isolation, genome sequencing and controlled experiments in lab mice, we show that the presence of the blood vessel allele is associated with resistance to a newly identified subspecies of Morganella morganii, a clinically important opportunistic pathogen. Given the increasing importance of zoonotic events, the approach outlined here may find useful application in the detection of emerging diseases in wild animal populations.

[Morganella sp. rods--characteristics, infections, mechanisms of resistance to antibiotics]. / Paleczki Morganella--charakterystyka, zakazenia, mechanizmy opornosci na antybiotyki.

The Morganella genus is one member of the tribe Proteae, which also includes the genera Proteus and Providencia. These bacteria are commonly present in the environment. Morganella sp. rods are known to be a causative agent of opportunistic hospital infections, mainly urinary tract, wound and blood infections of severe and high mortality, even in cases of an appropriate antibiotic. These bacteria may produce many virulence factors, for example urease, hemolysins, LPS, adhesins and enzymes hydrolyzing and modifying antibiotics commonly used to treat infections. Understanding the diverse biological properties of these rods may be of importance in the development of effective methods of prevention and control of infections with their participation.  

A Genomic and Bioinformatics View of the Classification and Evolution of Morganella Species and Their Chromosomal Accessory Genetic Elements Harboring Antimicrobial Resistance Genes.

In this study, draft-genome sequencing was conducted for 60 Chinese Morganella isolates, and furthermore, 12 of them were fully sequenced. Then, a total of 166 global sequenced Morganella isolates, including the above 60, were collected to perform average nucleotide identity-based genomic classification and core single nucleotide polymorphism-based phylogenomic analysis. A genome sequence-based species classification scheme for Morganella was established, and accordingly, the two conventional Morganella species were redefined as two complexes and further divided into four and two genospecies, respectively. At least 88 acquired antimicrobial resistance genes (ARGs) were disseminated in these 166 isolates and were prevalent mostly in the isolates from hospital settings. IS26/IS15DI, IS10 and IS1R, and Tn3-, Tn21-, and Tn7-subfamily unit transposons were frequently presented in these 166 isolates. Furthermore, a detailed sequence comparison was applied to 18 Morganella chromosomal accessory genetic elements (AGEs) from the fully sequenced 12 isolates, together with 5 prototype AGEs from GenBank. These 23 AGEs were divided into eight different groups belonging to composite/unit transposons, transposable prophages, integrative and mobilizable elements, and integrative and conjugative elements, and they harbored at least 52 ARGs involved in resistance to 15 categories of antimicrobials. Eleven of these 23 AGEs acquired large accessory modules, which exhibited complex mosaic structures and contained many antimicrobial resistance loci and associated ARGs. Integration of ARG-containing AGEs into Morganella chromosomes would contribute to the accumulation and dissemination of ARGs in Morganella and enhance the adaption and survival of Morganella under complex and diverse antimicrobial selection pressures. IMPORTANCE This study presents a comprehensive genomic epidemiology analysis on global sequenced Morganella isolates. First, a genome sequence-based species classification scheme for Morganella is established with a higher resolution and accuracy than those of the conventional scheme. Second, the prevalence of accessory genetic elements (AGEs) and associated antimicrobial resistance genes (ARGs) among Morganella isolates is disclosed based on genome sequences. Finally, a detailed sequence comparison of eight groups of 23 AGEs (including 19 Morganella chromosomal AGEs) reveals that Morganella chromosomes have evolved to acquire diverse AGEs harboring different profiles of ARGs and that some of these AGEs harbor large accessory modules that exhibit complex mosaic structures and contain a large number of ARGs. Data presented here provide a deeper understanding of the classification and evolution of Morganella species and also those of ARG-containing AGEs in Morganella at the genomic scale.

Impact of antibiotic susceptibility reporting on broad spectrum antibiotic use in serratia and morganella bacteremia.

To minimize broad-spectrum antibiotic use, our microbiology laboratory changed antibiotic susceptibility reporting for AmpC-beta-lactamase producing Serratia marcescens and Morganella morganii in blood cultures to include results of narrow spectrum 3rd generation cephalosporins. We assessed the impact of this change on broad-spectrum antibiotic use and clinical outcomes. All adult patients with Serratia marcescens or Morganella morganii in blood culture 2 years pre- and post-change of susceptibility reporting were retrospectively reviewed. Exclusion: more than one pathogen isolated in their blood culture, did not receive antibiotics or died within 48 hours of positive blood culture. Outcomes: Rates of broad-spectrum antibiotic use, in-hospital mortality, clinical response and microbiologic success. There were 30 patients pre-change and 46 patients post-change of reporting. Cefepime use (broad-spectrum) decreased from 46.7% to 6.5% (p < 0.001) and 3rd generation cephalosporin (narrow-spectrum) use increased (3.3% vs 34.8%, p = 0.0013) in the post-change cohort. This demonstrates the potential role of selective susceptibility reporting in antimicrobial stewardship.

Combined effects of host genetics and diet on human gut microbiota and incident disease in a single population cohort.

Human genetic variation affects the gut microbiota through a complex combination of environmental and host factors. Here we characterize genetic variations associated with microbial abundances in a single large-scale population-based cohort of 5,959 genotyped individuals with matched gut microbial metagenomes, and dietary and health records (prevalent and follow-up). We identified 567 independent SNP-taxon associations. Variants at the LCT locus associated with Bifidobacterium and other taxa, but they differed according to dairy intake. Furthermore, levels of Faecalicatena lactaris associated with ABO, and suggested preferential utilization of secreted blood antigens as energy source in the gut. Enterococcus faecalis levels associated with variants in the MED13L locus, which has been linked to colorectal cancer. Mendelian randomization analysis indicated a potential causal effect of Morganella on major depressive disorder, consistent with observational incident disease analysis. Overall, we identify and characterize the intricate nature of host-microbiota interactions and their association with disease.

Bacterial kinetics-controlled shape-directed biosynthesis of silver nanoplates using Morganella psychrotolerans.

We show for the first time that by controlling the growth kinetics of Morganella psychrotolerans, a silver-resistant psychrophilic bacterium, the shape anisotropy of silver nanoparticles can be achieved. This is particularly important considering that there has been no report that demonstrates a control over shape of Ag nanoparticles by controlling the growth kinetics of bacteria during biological synthesis. Additionally, we have for the first time performed electrochemistry experiments on bacterial cells after exposing them to Ag(+) ions, which provide significant new insights about mechanistic aspects of Ag reduction by bacteria. The possibility to achieve nanoparticle shape control by using a "green" biosynthesis approach is expected to open up new exciting avenues for eco-friendly, large-scale, and economically viable shape-controlled synthesis of nanomaterials.

Phylogenetic analysis of the genera Proteus, Morganella and Providencia by comparison of rpoB gene sequences of type and clinical strains suggests the reclassification of Proteus myxofaciens in a new genus, Cosenzaea gen. nov., as Cosenzaea myxofaciens comb. nov.

Phylogenetic analysis of partial rpoB gene sequences of type and clinical strains belonging to different 16S rRNA gene-fingerprinting ribogroups within 11 species of enterobacteria of the genera Proteus, Morganella and Providencia was performed and allowed the definition of rpoB clades, supported by high bootstrap values and confirmed by ≥2.5 % nucleotide divergence. None of the resulting clades included strains belonging to different species and the majority of the species were confirmed as discrete and homogeneous. However, more than one distinct rpoB clade could be defined among strains belonging to the species Proteus vulgaris (two clades), Providencia alcalifaciens (two clades) and Providencia rettgeri (three clades), suggesting that some strains represent novel species according to the genotypes outlined by rpoB gene sequence analysis. Percentage differences between the rpoB gene sequence of the type strain of Proteus myxofaciens and other members of the same genus (17.3-18.9 %) were similar to those calculated amongst strains of the genus Providencia (16.4-18.7 %), suggesting a genetic distance at the genus-level between Proteus myxofaciens and the rest of the Proteus-Providencia group. Proteus myxofaciens therefore represents a member of a new genus, for which the name Cosenzaea gen. nov., is proposed.

An implication of biotransformation in detoxification of mercury contamination by Morganella sp. strain IITISM23.

The contamination of soil by heavy metals such as Hg is growing immensely nowadays. The drawbacks of physicochemical methods in the decontamination of polluted soils resulted in the search for an eco-friendly and cost-effective means in this regard. In this study, a potential Hg-resistant bacterial (IITISM23) strain was investigated for their removal potential of Hg, isolated from Hg-contaminated soil. IITISM23 strain was identified as Morganella sp. (MT062474.1) as it showed 99% similarity to genus Morganella of Gammaproteobacteria based on 16S rRNA gene sequencing. The toxicity experiment confirmed that the strain showed high resistance toward Hg. In low nutrient medium, EC50 (effective concentration) values were 6.8 ppm and minimum effective concentration (MIC) was 7.3 ppm, and in a nutrient-rich medium, EC50 value was 32.29 ppm and MIC value was 34.92 ppm, respectively. In in vitro conditions, IITISM23 showed the removal efficiency (81%) of Hg (II) by the volatilization method in Luria-Bertani (LB) broth. The changes in surface morphology of bacteria upon the supplementation of Hg (II) in broth media were determined by SEM-EDX studies, while the changes in functional groups were studied by FT-IR spectroscopy. The mercury reductase activity was determined by a crude extract of the bacterial strain. The optimal pH and temperature for maximum enzyme activity were 8 and 30oC, with Km of 3.5 µmol/l and Vmax of 0.88 µmol/min, respectively. Also, strain IITISM23 showed resistance toward various antibiotics and other heavy metals like cadmium, lead, arsenic, and zinc. Hence, the application of microbes can be an effective measure in the decontamination of Hg from polluted soils.

Importance of Reviewing Antibiotic Courses by 48 Hours: Risk Factors for Third-Generation Cephalosporin Resistance Among AmpC Harboring Organisms in Urine and Respiratory Cultures.

BACKGROUND: Citrobacter, Enterobacter, Morganella, and Serratia (AmpC organisms) species can exhibit third-generation cephalosporin (TGC) resistance after TGC exposure. We aimed to assess if institutional TGC utilization correlated with institutional AmpC organism susceptibility and if prior TGC exposure ≤48 hours were associated with TGC resistance in the first culture of a future infection episode caused by an AmpC organism. METHODS: A 5-year retrospective cohort study was performed, including AmpC organisms isolated from pediatric urinary and respiratory tract cultures at an institution with TGC courses reviewed by the antimicrobial stewardship program at 48 hours. Correlations were assessed by Pearson's correlation. Multivariable logistic regression identified factors independently associated with TGC resistance in a subcohort of infection episodes. RESULTS: Among 654 cultures, AmpC organism TGC susceptibility increased from 74% in 2013 to 89.3% in 2017, and this correlated with a 26.1% decrease in TGC utilization (R = -0.906; P = 0.034). Among 275 AmpC organism infections, 21.1% were resistant. Resistance occurred in 13.6%, 17.4%, and 56.5% of infections with no exposure, ≤48 hours, and >48 hours of TGC exposure in the past 30 days, respectively. TGC exposure ≤48 hours was not associated with resistance (odds ratio [OR], 1.26; 95% confidence interval [CI], 0.32-4.94; P = 0.74), whereas, TGC exposure >48 hours was (OR, 8.7; 95% CI, 3.67-20.6; P < 0.001). Infections in 2017 were less likely to be resistant (OR, 0.25; 95% CI, 0.08-0.8; P = 0.019). CONCLUSIONS: Decreased TGC utilization, likely related to antimicrobial stewardship, correlated with increased AmpC organism susceptibility. Limiting TGC exposure to ≤48 hours when possible may reduce AmpC organism resistance in future infections.

Understanding the role of SilE in the production of metal nanoparticles by Morganella psychrotolerans using MicroScale Thermophoresis.

Metal nanoparticle synthesis has been observed in several species of bacteria but the underlying mechanisms of synthesis are not well understood. Morganella psychrotolerans is a Gram-negative psychrophilic bacterium that is able to tolerate relatively high concentrations of Cu and Ag ions, and it is through the associated resistance pathways that this species is able to convert metal ions to nanoparticles. The purpose of this study was to investigate the mechanism of nanoparticle synthesis, looking at the interaction of the metal binding protein SilE with metal ions using MicroScale Thermophoresis (MST). MST assays give a rapid and accurate determination of binding affinities, allowing for the testing of SilE with a range of environmentally significant metal ions. The binding affinities (Kd) of Ag+ and Cu2+ were measured as 0.17 mM and 0.13 mM respectively, consistent with the observations of strong binding reported in the literature, whereas the binding to Al3+ and Co2+ was measured as Kd values of 4.19 mM and 1.35 mM respectively.

Antimicrobial susceptibility and distribution of extended-spectrum ß-lactamases, AmpC ß-lactamases and carbapenemases among Proteus, Providencia and Morganella isolated from global hospitalised patients with intra-abdominal and urinary tract infections: Results of the Study for Monitoring Antimicrobial Resistance Trends (SMART), 2008-2011.

OBJECTIVES: The increasing trend of ß-lactam resistance among Enterobacteriaceae is a worldwide problem. This study investigated isolates of the tribe Proteeae (Proteus, Providencia and Morganella) causing intra-abdominal and urinary tract infections from the worldwide Study for Monitoring Antimicrobial Resistance Trends (SMART) collected from 2008-2011. METHODS: Antimicrobial susceptibility testing was performed on isolates with an ertapenem minimum inhibitory concentration >0.5mg/L or those phenotypically producing extended-spectrum ß-lactamases (ESBLs). ESBLs, AmpC ß-lactamases and carbapenemases were detected by multiplex PCR. RESULTS: A total of 142 isolates, including Proteus mirabilis (n=121), Proteus vulgaris (n=3), Providencia stuartii (n=5), Providencia rettgeri (n=6) and Morganella morganii (n=7), were analysed. Proteus mirabilis was generally susceptible to ertapenem (∼90%) compared with imipenem (≤25%). The most common ESBLs were CTX-M types (n=64), followed by TEM (n=27) and SHV (n=7). CTX-M-1, CTX-M-2 and CTX-M-15 were the dominant CTX-M-type ESBLs in P. mirabilis isolates. CMY (n=14), which included CMY-2 (n=6), was the most common AmpC ß-lactamase, followed by DHA (n=6) and FOX (n=4). NDM (n=7), which included NDM-1 (n=4), was the most common carbapenemase, followed by KPC (n=2). Isolates from hospital-associated infections had more complicated ß-lactamase combinations than isolates from community-acquired infections. CONCLUSION: The global emergence and spread of ß-lactamase-producing Proteeae isolates are major issues in tackling antimicrobial resistance. Continuous monitoring of antimicrobial resistance trends and developing further resistance surveillance are necessary.

High prevalence of multiple drug resistant enteric bacteria: Evidence from a teaching hospital in Southwest Nigeria.

The development and evolution of antimicrobial resistance (AMR) in pathogens has been reported to be one of the major issues confronting the global health community. The aim of this study was to examine the period prevalence of antibiotic resistance, as well as the trends and patterns in sensitivity profile of enteric bacteria isolated from urine samples of patients with UTIs in a teaching Hospital in south west Nigeria. Urine samples were collected from 77 patients with UTIs from February 2017 to October 2018. Standard laboratory methods were used for urine sample culture and bacterial identification. The Kirby-Bauer disk diffusion method was used to evaluate antimicrobial sensitivity. Predominant enteric bacteria isolates were Escherichia coli (24, 39.3%), Salmonella species (12, 19.7%), Klebsiella species (4, 6.6%), Providencia species (6, 9.8%), Proteus species (8, 13.1%), Serratia species (2, 3.3%), Yersinia species (1, 1.6%) and Morganella species (4, 6.6%). A large proportion (90.2%) of isolates obtained were multi-drug resistant. High resistance in amoxycillin-clavulanate (98%), cefuroxime (92%), erythromycin (90%) and ceftazidime (84%) were recorded. These results emphasize the importance of continuous screening and surveillance programmes for detection of AMR in enteric bacteria of public health importance.

Extracellular synthesis of crystalline silver nanoparticles and molecular evidence of silver resistance from Morganella sp.: towards understanding biochemical synthesis mechanism.

There has been significant progress in the biological synthesis of nanomaterials. However, the molecular mechanism of synthesis of such bio-nanomaterials remains largely unknown. Here, we report the extracellular synthesis of crystalline silver nanoparticles (AgNPs) by using Morganella sp., and show molecular evidence of silver resistance by elucidating the synthesis mechanism. The AgNPs were 20+/-5 nm in diameter and were highly stable at room temperature. The kinetics of AgNPs formation was investigated. Detectable particles were formed after an hour of reaction, and their production remained exponential up to 18 h, and saturated at 24 h. Morganella sp. was found to be highly resistant to silver cations and was able to grow in the presence of more than 0.5 mM AgNO(3). Three gene homologues viz. silE, silP and silS were identified in silver-resistant Morganella sp. The homologue of silE from Morganella sp. showed 99 % nucleotide sequence similarity with the previously reported gene, silE, which encodes a periplasmic silver-binding protein. The homologues of silP and silS were also highly similar to previously reported sequences. Similar activity was totally absent in closely related Escherichia coli; this suggests that a unique mechanism of extracellular AgNPs synthesis is associated with silver-resistant Morganella sp. The molecular mechanism of silver resistance and its gene products might have a key role to play in the overall synthesis process of AgNPs by Morganella sp. An understanding of such biochemical mechanisms at the molecular level might help in developing an ecologically friendly and cost-effective protocol for microbial AgNPs synthesis.

Growth, inactivation and histamine formation of Morganella psychrotolerans and Morganella morganii - development and evaluation of predictive models.

Mathematical models for growth, heat inactivation and histamine formation by Morganella psychrotolerans and Morganella morganii were studied to evaluate the importance of these bacteria in seafood. Curves for growth and histamine formation by M. psychrotolerans in broth and seafood were generated at constant and changing storage temperatures (n=12). Observed and predicted times to formation of 100, 500 and 2000 ppm histamine were used for evaluation of an existing M. psychrotolerans histamine formation model [Emborg, J., Dalgaard, P., 2008-this issue-this issue. Modelling and predicting the growth and histamine formation by Morganella psychrotolerans. International Journal of Food Microbiology. doi:10.1016/j.ijfoodmicro.2008.08.016] Growth rates for M. psychrotolerans and M. morganii were determined at different constant temperatures from 0 degrees C to 42.5 degrees C whereas heat inactivation was studied between 37.5 degrees C and 60 degrees C. A M. morganii growth and histamine formation model was developed by combining these new data (growth rate model) and data from the existing literature (maximum population density and yield factor for histamine formation). The developed M. morganii model was evaluated by comparison of predicted growth and histamine formation with data from the existing literature. Observed and predicted growth rates for M. psychrotolerans, at constant temperatures, were similar with bias- and accuracy factor values of 1.15 and 1.45, respectively (n=11). On average times to formation of critical concentrations of histamine by M. psychrotolerans were acceptably predicted but the model was not highly accurate. Nevertheless, predictions seemed useful to support decisions concerning safe shelf-life in relation to formulation, storage and distribution of chilled seafood. Parameters for the effect of temperature on growth and inactivation of M. psychrotolerans and M. morganii differed markedly with Tmin of -8.3 to -5.9 degrees C vs. 0.3 to 2.8 degrees C, Topt of 26.0 to 27.0 degrees C vs. 35.9 to 37.2 degrees C and Tmax 32.0 to 33.3 degrees C vs. 44.0 to 47.4 degrees C, D(50 degrees C) of 5.3 min vs. 13.1 min and z-values of 6.8 degrees C and 7.2 degrees C. At temperatures above approximately 15 degrees C M. morganii grew faster than M. psychrotolerans. Bias- and accuracy factor-values of 1.41 and 2.44 (n=93) showed the predicted growth of M. morganii to be faster than previously observed in fresh fish and broth. In agreement with this, predicted times to formation of critical histamine concentrations by M. morganii were on average shorter than observed in fresh fish. A combined model was suggested to predict histamine formation by both psychrotolerant and mesophilic Morganella during storage of fresh fish between 0 degrees C and 37 degrees C.

Modelling the effect of temperature, carbon dioxide, water activity and pH on growth and histamine formation by Morganella psychrotolerans.

A mathematical model was developed to predict growth and histamine formation by Morganella psychrotolerans depending on temperature (0-20 degrees C), atmosphere (0-100% CO2), NaCl (0.0-6.0%) and pH (5.4-6.5). Data from experiments with both sterile tuna meat and Luria Bertani broth was used to develop the mathematical growth and histamine formation model. The expanded Logistic model with a growth dampening parameter (m) of 0.7 was used as primary growth model. A primary model for histamine formation during storage was obtained by combining the expanded Logistic growth model with a yield factor (YHis/CFU). 120 maximum specific growth rate (micromax)-values were generated for M. psychrotolerans and used to model the combined effect of the studied environmental parameters. A simple cardinal parameter type secondary model was used to model the effect of the four parameters on micro(max). The maximum population density (log Nmax) was correlated with log (YHis/CFU) and a simple constrained polynomial (quadratic) secondary model was developed for the effect of the environmental conditions on these model parameters. The developed model describes the effect of initial cell concentrations, storage conditions and product characteristics on histamine formation. This is a significant progress compared to previously available models for the effect of storage temperature only.