Myroides odoratus and Chryseobacterium indologenes: Two rare isolates in the immunocompromised

Secondary bacterial corneal infection caused by Myroides species in primary fungal keratitis

A middle-aged male patient presented with a central corneal perforation in a deep stromal infiltrate in his left eye. An emergency therapeutic penetrating keratoplasty was performed. Microbiological evaluation of the corneal scraping specimen revealed septate fungal filaments on stains. However, culture reports after 24 hours from the scraping sample and the excised half corneal button showed growth of gram-negative bacilli. This pathogen was identified as an aerobic, non-fermentative, gram-negative, bacillus by conventional microbiology and confirmed as Myroides species by the VITEK 2 Compact system (bioMérieux, Marcy l'Etoile, France). Susceptibility to chloramphenicol was noted based on which the patient was treated with topical chloramphenicol 0.5%. No recurrence of the infection was noted. This is the first reported case of corneal infection with the Myroides species of bacteria which, heretofore, have been known to cause endocarditis and urinary tract infections.

A Retrospective Study on UTI by Myroides Species: An Emerging Drug Resistant Nosocomial Pathogen

Aim and background

Myroides (M.) species are ubiquitous in the environment and cause a variety of infections like urinary tract infections (UTI), sepsis, meningitis, cholecystitis, pneumonia, and soft tissue infections, especially among immunocompromised populations. These are usually resistant to multiple antibiotics. This study aimed to demonstrate the clinical profile, underlying comorbidities, and antimicrobial susceptibility of Myroides isolates obtained from nosocomial UTI cases.

Materials and methods

A sudden rise in the isolation of Myroides spp. from the repeated urine samples of admitted patients alerted us to conduct this retrospective observational study. Urine cultures that grew M. species were included in this study. Antibiotic susceptibility was performed and the patient's clinical data was analyzed.

Results

A total of 14 Myroides spp. isolates were obtained from urine culture. The maximum number of cases (71.4%) were from the Nephrology ward and ICUs. The average (mean) age of patients was 46 years (range 2-80 years). All patients were catheterized. All isolates were multidrug resistant. Minocycline and doxycycline were the only drugs found effective in this study.

Conclusions

Myroides species are emerging rare pathogens that can cause UTI in immunocompromised and catheterized patients. Minocycline may be used for treating such infections.

How to cite this article

Sahu C, Chaudhary R, Bhartiya C, Patel SS, Bhatnagar N. A Retrospective Study on UTI by Myroides Species: An Emerging Drug Resistant Nosocomial Pathogen. Indian J Crit Care Med 2024;28(4):399-403.

Size-resolved ambient bioaerosols concentration, antibiotic resistance, and community composition during autumn and winter seasons in Qatar

This study investigates the size distribution, microbial composition, and antibiotic resistance (ABR) of airborne bioaerosols at a suburban location in Doha, Qatar between October 2021 and January 2022. Samples were collected using an Andersen six-stage viable cascade impactor and a liquid impinger. Findings showed that the mean bacteria concentration (464 CFU/m3) was significantly higher than that of fungi (242 CFU/m3) during the study period. Both bacteria and fungi were most abundant in the aerodynamic size fractions of 1.10-2.21 μm, with peak concentrations observed in the mornings and lowest concentrations in the afternoons across all size fractions. A total of 24 different culturable species were identified, with the most abundant ones being Pasteurella pneumotropica (9.71%), Pantoea spp. 1 (8.73%), and Proteus penneri (7.77%) spp. At the phylum level, the bacterial community configurations during the autumn and winter seasons were nearly identical as revealed by molecular genomics, with Proteobacteria being the most predominant, followed by Firmicutes, Bacteroidetes, Acidobacteriota, and Planctomycetota. However, there was a significant variation in dominant genera between autumn and winter. The most abundant genera included Sphingomonas, Paraburkholderia, Comamonas, Bacillus, and Lysinibacillus. Several bacterial genera identified in this study have important public health and ecological implications, including the risk of respiratory tract infections. Furthermore, the study found that ABR was highest in December, with bioaerosols exhibiting resistance to at least 5 out of 10 antibiotics, and 100% resistance to Metronidazole in all samples. Metagenomics analysis revealed the presence of various airborne bacteria that were not detected through culture-dependent methods. This study provides valuable insights into the airborne microbial composition, temporal variability and ABR in the Arabian Gulf region.

A case series and literature review of infections due to Myroides spp.: identification of contributing factors and emerging antibiotic susceptibility trends

Introduction

Infections forby Myroides spp. can lead to significant morbidity and mortality, particularly in immunocompromised patients with underlying co-morbidities. Recent reports have highlighted its intrinsic and acquired drug resistance, making it a particularly challenging infectious agent to combat.

Methods

Myroides spp. isolated and reported in clinically significant urine samples were considered for the study. Identification of the organism was done via the VITEK 2C system. Antibiotic susceptibility testing was done using both manual and automated methods following Clinical and Laboratory Standards Institute (CLSI) guidelines. Existing literature was searched on MEDLINE using PubMed.

Results

We present a series of five catheter-associated urinary tract infections due to Myroides odoratimimus , with sensitivity to only minocycline. This is the first case from Western India, and the third case in the existing literature that shows Myroides sensitivity only to minocycline. Our literature review is the first to systematically describe contributory factors to infection, allowing us to devise a clinically relevant tool that delineates contributory factors and efficacious drugs in Myroides spp. infection.

Conclusion

Myroides spp. infections, previously considered rare and opportunistic, need cognizance and diagnostic suspicion especially in particular associated conditions.

Characterization and Identification of a novel chromosome-encoded metallo-β-lactamase WUS-1 in Myroides albus P34

In this study, we identified and characterized a novel chromosomally-encoded class B metallo-β-lactamase (MBL) gene designated bla WUS-1 in a carbapenem-resistant isolate Myroides albus P34 isolated from sewage discharged from an animal farm. Comparative analysis of the deduced amino acid sequence revealed that WUS-1 shares the highest amino acid similarities with the function-characterized MBLs MUS-1 (AAN63647.1; 70.73%) and TUS-1 (AAN63648.1; 70.32%). The recombinant carrying bla WUS-1 exhibited increased MICs levels against a number of β-lactam antimicrobials such as carbenicillin, ampicillin and imipenem, and β-lactamase inhibitors (clavulanic acid and tazobactam). The metallo-β-lactamase WUS-1 could also hydrolyze these antimicrobials and the hydrolytic activities could be inhibited by EDTA. Genetic context analysis of bla WUS-1 revealed that no mobile genetic element was found in its surrounding region. The plasmid pMA84474 of Myroides albus P34 harbored 6 resistance genes (bla OXA-347, aadS, bla MYO-1, ereD, sul2 and ermF) within an approximately 17 kb multidrug resistance (MDR) region. These genes, however, were all related to mobile genetic elements.

Extensively Drug-Resistant Myroides odoratus in Critically Ill Patients: A Case Series and Literature Review

The bacterial genus Myroides, like other members of the Flavobacteriaceae family, consists of aerobic, non-motile, Gram-negative bacilli. Myroides spp. is considered predominantly opportunistic pathogens as, historically, most documented infections have been in immunocompromised individuals. Along with advancements in molecular assay testing, there are growing reports of clinically relevant Myroides spp. infections in immunocompetent individuals. These organisms display broad antimicrobial resistance, and while research into their mechanisms of resistance is progressing, genetic testing has revealed metallo-β-lactamases present in their genome. The sporadic identification of Myroides spp. and ongoing clarification of resistance patterns make empiric treatment difficult. This report documents two cases of extensively drug-resistant Myroides odoratus isolated from critically ill but otherwise immunocompetent patients followed by a review of available literature on Myroides spp. antibiotic sensitivities. Our findings indicate that minocycline and moxifloxacin have the highest documented in vitro activity against Myroides spp.

A Confirmed Catheter-Related Blood Stream Infection (CRBSI) in an Immunocompetent Patient Due to Myroides odoratimimus: Case Report and Literature Review

The genus Myroides are gram-negative bacilli which are completely aerobic, non-motile, non-fermenting and yellow-pigmented with a characteristic fruity odor. Myroides species are widely found in the environment, especially in water and soil, and are considered as low-grade opportunistic pathogens for humans. Myroides infections are most commonly seen in immunocompromised patients and only rarely occur in immunocompetent patients. We here report the first confirmed catheter-related bloodstream infection (CRBSI) due to Myroides odoratimimus in an immunocompetent patient. We also review the literature related to Myroides infections.

Association of Myroides odoratimimus in immunocompromized piglets with post weaning multisystemic wasting syndrome

AIM

To study the association of opportunistic infection due to Myroides odoratimimus in piglets immunocompromised by porcine circovirus type 2 (PCV2) infection.

METHODS AND RESULTS

The clinical samples (n = 101) were analysed bacteriologically. The isolates were identified by their phenotypes and MALDI TOF-MS analysis as Myroides species. The phylogram constructed based on nucleotide sequences of the 16S rRNA gene showed identity (~99%) with the M. odoratimimus isolates. The minimum inhibitory concentration values for antibiotics revealed M. odoratimimus to be resistant against carbapenem, cephalosporins, aminoglycosides and fluoroquinolones. The presence of PCV2 in affected tissue samples was confirmed by amplification of the 565 bp region of ORF2 of the PCV2 genome. The topology of the phylogenetic tree grouped the PCV2 with cluster-2d.

CONCLUSIONS

PCV2 being immunosuppressive in nature might have impaired the immunity thereby increasing the susceptibility of immunocompromised piglets to opportunistic pathogens such as M. odoratimimus leading to disease severity and high mortality. The M. odoratimimus isolates were found to be multidrug resistant and evidenced for uncertain clinical relevance and hence could act as hidden source of public health hazard.

SIGNIFICANCE AND IMPACT OF THE STUDY

Myroides odoratimimus is a rarely reported human pathogen. We reported the incidence of infection due to seemingly rare isolates of M. odoratimimus causing an outbreak of pneumonia in piglets. This appears, to the best of authors' knowledge, to be the first outbreak due to Myroides recorded in animal clinical cases described in the literature.

Myroides injenensis Bacteremia and Severe Cellulitis

Myroides spp. are environmental bacterial organisms that rarely cause disease in humans. Myroides spp. infections are infrequently reported in the literature, and Myroides injenensis infections are quite uncommon. Myroides spp. usually infect immunocompromised hosts and can have highly resistant antibiotic susceptibility patterns. Here we report a case of Myroides injenensis bacteremia and severe cellulitis in a patient with cirrhosis and review the literature of other Myroides spp. infections.

Whole-genome sequencing of a large collection of Myroides odoratimimus and Myroides odoratus isolates and antimicrobial susceptibility studies

The genus Myroides comprises several species of Gram-negative, non-motile, and non-fermenting bacteria, which have been regarded as non-pathogenic for decades. Multiple recent reports, however, underscore the pathogenic potential that Myroides sp. possesses for humans. These bacteria seem to be resistant to a wide range of antibiotics (including ß-lactams and aminoglycosides). Therefore, treatment options are limited. Knowledge of antimicrobial resistance, however, is based on only one meaningful comprehensive study and on data published from case reports. This lack of data motivated us to test 59 strains from our Myroides collection (43 M. odoratimimus and 16 M. odoratus) for resistance against 20 commonly used antibiotics. We also performed molecular analyses to reveal whether our bacteria harbor the genus-specific M. odoratimimus metallo-ß-lactamase (MUS-1) or the M. odoratus metallo ß-lactamase (TUS-1), and other ß-lactamases, which may provide an explanation for the extended antimicrobial resistance.

Draft Genome Sequence of Chryseobacterium mucoviscidosis sp. nov. Strain VT16-26, Isolated from the Bronchoalveolar Lavage Fluid of a Patient with Cystic Fibrosis

We report here the draft genome sequence of Chryseobacterium mucoviscidosis VT16-26, a novel bacterium isolated from the lungs of a patient with cystic fibrosis. The genome was composed of 4,403,956 bp and had 36.2% G+C content. We detected 4,048 genes with predicted protein-coding functions, including those associated with antibiotic resistance and virulence.

Myroides bacteremia: A case report and concise review

Myroides species are bacteria found commonly in environmental sources, such as water and soil. Despite this, they are historically uncommon pathogens, tending to affect primarily immunocompromised hosts. Based on a review of the current cases listed in the U.S. National Institutes of Health's National Library of Medicine (Table 1), there have been 48 reported cases of infection to date, one third of which have been reported in only the last seven years. This report outlines a case of bacteremia caused by Myroides species occurring in a diabetic male on chemotherapy for Merkel cell cancer. Myroides species can be difficult to treat, many strains are resistant to several antibacterial classes, this patient was treated successfully with meropenem.

CO2 sequestration by ureolytic microbial consortia through microbially-induced calcite precipitation

Urea is an abundant nitrogen-containing compound found in urine of mammals and widely used in fertilizers. This compound is part of the nitrogen biogeochemical cycle and is easily biodegraded by ureolytic microorganisms that have the urease enzyme. Previous studies, with ureolytic isolates, have shown that some ureolytic microorganisms are able to sequester CO₂ through a process called microbially-induced calcium carbonate precipitation. The present study investigates 15 ureolytic consortia obtained from the "Pamukkale travertines" and the "Cave Without A Name" using different growth media to identify the possible bacterial genera responsible for CO₂ sequestration through the microbially-induced calcite precipitation (MICP). The community structure and diversity were determined by deep-sequencing. The results showed that all consortia presented varying CO₂ sequestration capabilities and MICP rates. The CO₂ sequestration varied between 0 and 86.4%, and it depended largely on the community structure, as well as on pH. Consortia with predominance of Comamonas, Plesiomonas and Oxalobacter presented reduced CO₂ sequestration. On the other hand, consortia dominated by Sporosarcina, Sphingobacterium, Stenotrophomonas, Acinetobacter, and Elizabethkingia showed higher rates of CO₂ uptake in the serum bottle headspace.

Molecular identification of bacterial endosymbionts of Sappinia strains

The genus Sappinia comprises free-living amoebae occurring worldwide in a variety of habitats such as soils, plant matter and freshwater ponds, but also animal faeces, and includes at present three species, S. pedata, S. diploidea and S. platani. The genus is potentially pathogenic, as indicated by the identification of S. pedata in a case of human amoebic encephalitis. Electron microscopy studies on some strains already revealed intracellular bacteria in Sappinia. In the current study, we performed 16S ribosomal RNA gene (rDNA) analysis of these bacterial endosymbionts. We first inferred relationships among Sappinia strains on the basis of 18S rDNA, demonstrating that S. pedata emerged as sister to a larger clade including S. diploidea, S. platani and a few 'S. diploidea-like' strains. Thus, bacterial 16S rDNA was searched for in representative strains of each Sappinia species/subgroup. We found that Sappinia strains were associated to distinct species of Flavobacterium or Pedobacter (phylum Bacteroidetes). These appear to be distributed following the amoebal host subgroups, and are not directly related to other Bacteroidetes species known as interacting with free-living amoebae. While all the endosymbionts' close relatives are known to grow on agar, bacteriological media inoculated with amoebal extracts remained negative. Overall, results indicate that the recovered bacteria are likely specific obligate endosymbionts of Sappinia species. Further studies, including additional amoebal strains and deep morphological and molecular analyses, will be necessary to confirm this hypothesis.

Fatal Case of Pericardial Effusion Due to Myroides Odoratus: A Rare Case Report

Myroides spp., previously known as Flavobacterium odoratum, are rare clinical isolates and are often considered non-pathogenic. Natural habitat includes soil, fresh and marine waters, in foods and in sewage treatment plants. We present an unusual case of fatal pericardial effusion due to Myroides odoratus in a patient suffering from chronic kidney disease and undergoing maintenance haemodialysis. This case is presented to show the increasing incidence of rare isolates causing localized and systemic infections and due to their high intrinsic resistance to many antibiotics they can be fatal. Thus isolation of these pathogens is of great clinical importance.

Multidrug Resistance in Quinolone-Resistant Gram-Negative Bacteria Isolated from Hospital Effluent and the Municipal Wastewater Treatment Plant

This study is aimed to assess if hospital effluents represent an important supplier of multidrug-resistant (MDR) Gram-negative bacteria that, being discharged in the municipal collector, may be disseminated in the environment and bypassed in water quality control systems. From a set of 101 non-Escherichia coli Gram-negative bacteria with reduced susceptibility to quinolones, was selected a group of isolates comprised by those with the highest indices of MDR (defined as nonsusceptibility to at least one agent in six or more antimicrobial categories, MDR ≥6) or resistance to meropenem or ceftazidime (n = 25). The isolates were identified and characterized for antibiotic resistance phenotype, plasmid-mediated quinolone resistance (PMQR) genes, and other genetic elements and conjugative capacity. The isolates with highest MDR indices were mainly from hospital effluent and comprised ubiquitous bacterial groups of the class Gammaproteobacteria, of the genera Aeromonas, Acinetobacter, Citrobacter, Enterobacter, Klebsiella, and Pseudomonas, and of the class Flavobacteriia, of the genera Chryseobacterium and Myroides. In this group of 25 strains, 19 identified as Gammaproteobacteria harbored at least one PMQR gene (aac(6')-Ib-cr, qnrB, qnrS, or oqxAB) or a class 1 integron gene cassette encoding aminoglycoside, sulfonamide, or carbapenem resistance. Most of the E. coli J53 transconjugants with acquired antibiotic resistance resulted from conjugation with Enterobacteriaceae. These transconjugants demonstrated acquired resistance to a maximum of five classes of antibiotics, one or more PMQR genes and/or a class 1 integron gene cassette. This study shows that ubiquitous bacteria, other than those monitored in water quality controls, are important vectors of antibiotic resistance and can be disseminated from hospital effluent to aquatic environments. This information is relevant to support management options aiming at the control of this public health problem.

MYROIDES INFECTION IN A BABOON AFTER PROLONGED PIG KIDNEY GRAFT SURVIVAL

BACKGROUND

Immunosuppressed patients and experimental nonhuman primates are at risk of opportunistic infection. We report a Myroides spp infection in an immunosuppressed baboon that had received a life-supporting kidney from a genetically-engineered pig.

CASE REPORT

The baboon received a costimulation blockade-based immunosuppressive regimen as well as two anti-inflammatory agents (tocilizumab and etanercept). Although the pig kidney functioned well, approximately four months after the transplant the baboon became less active and ate and drank poorly. On day 136, it collapsed and died despite inotropic and fluid support. A blood culture drawn before death grew Myroides spp.

DISCUSSION AND CONCLUSIONS

To our knowledge, Myroides spp has not been reported as a cause of opportunistic infection in either patients with organ allotransplants or experimental animals. We summarize what is known about this rare organism, and suggest it should be considered in any immunocompromised patient or animal. In the present case, we suggest the baboon died of circulatory shock following infection through an indwelling intravenous catheter.