Morganella morganii : An unusual analysis of 11 cases of pediatric urinary tract infections

Association between gut microbiota in HIV-infected patients and immune reconstitution following antiretroviral therapy (ART)

BACKGROUND

This study aims to examine the potential link between incomplete immune reconstitution following ART treatment and gut microbiota dysbiosis.

METHODS

We collected clinical data and fecal samples from 50 HIV patients undergoing ART and 30 untreated patients. Based on the observed immune function reconstruction, we further categorized the ART(+) group into a responder group (n = 30) and a non-responder group (n = 20). The gut microbiota composition differences were assessed using Alpha diversity and Beta diversity analysis, while differential genera were identified through linear discriminant analysis effect size (LEfSe). Subsequently, functional disparities in the gut microbiota were investigated using PICRUSt2 and metagenomeSeq software.

RESULTS

The results of Alpha diversity and Beta diversity revealed significant differences in the composition of gut microbiota among the three groups. Differential genus analysis identified Morganella as an exclusive genus present only in the Non-responder group, exhibiting a significantly higher relative abundance. Correlation analysis demonstrated a positive association between Morganella and LDL levels. The CAZY analysis revealed that glycosyltransferase 25 (GT25) was significantly expressed in the Non-responder group, whereas it was either undetectable or exhibited extremely low expression levels in both the Responder group and the ART(-) group. Importantly, the correlation analysis indicated a positive association between Morganella and GT25 secretion.

CONCLUSIONS

The ecological imbalance of Morganella might be associated with incomplete immune reconstitution following ART, potentially mediated by GT25 secretions. Consequently, Morganella could serve as a promising biomarker for predicting incomplete immune reconstitution in AIDS patients undergoing ART.

Molecular mechanisms of resistance in Morganella morganii with exclusive resistance to imipenem: Whole genome sequencing analysis of 12 clinical isolates

BACKGROUND

Morganella morganii (M. morganii) is a significant opportunistic pathogen, increasingly linked to infections with high mortality rates.

OBJECTIVE

This study aimed to explore the resistance mechanisms and molecular profiles of 12 clinical M. morganii isolates exclusively resistant to imipenem, employing whole genome sequencing (WGS) to guide infection prevention and control strategies.

METHODS

A retrospective analysis of 12 isolates from a tertiary hospital, collected between May 2014 and March 2023, was conducted, incorporating strain identification and antimicrobial susceptibility testing. Genomic data were acquired via WGS, followed by gene analysis and replicon typing using Abricate. A broader epidemiological assessment of 227 Morganella isolates was performed using Snippy, Gubbins, and FastTree, leading to the construction of a phylogenetic tree to delineate evolutionary relationships.

RESULTS

Three M. morganii isolates were identified as exclusively imipenem-resistant, while remaining susceptible to meropenem and ertapenem, each harboring carbapenemase resistance genes, blaKPC-2, blaNDM-1, and blaOXA-48, respectively. Replicon type analysis revealed that isolate GK07 carried two replicons: IncL/M(pOXA-48)_1_pOXA-48 and IncX8_1.

CONCLUSION

These findings suggest that selective imipenem resistance in M. morganii may be associated with carbapenemase genes and the potential for plasmid-mediated horizontal transmission of resistant clones. The results highlight the need for continuous monitoring of resistance gene dissemination across hosts, targeted interventions to curb resistant clone spread, and sustained vigilance regarding global epidemiological trends.

Genomic epidemiology and antimicrobial resistance of Morganella clinical isolates between 2016 and 2023

Morganella morganii is a Gram-negative, opportunistic pathogen that is often associated with nosocomial infections. Here, the genomic characteristics and antimicrobial resistance (AMR) of Morganella clinical isolates between 2016 and 2023 were determined. A total of 218 clinical isolates were mainly identified from urinary tract (48.2%) and respiratory tract (16.5%), with 105 isolates randomly selected for whole genome sequencing. The highest rates of antibiotic resistance were observed with SAM (68.3%), followed by CIP (39.9%), and SXT (37.2%). Distance analysis suggested that the 105 newly sequenced isolates could be divided into two groups: M. morganii subsp. morganii and M. morganii subsp. sibonii. While, the average nucleotide identity between these groups showed only 91.5-92.2% similarity, raising the possibility that they may be distinct species. Phylogenomic analysis revealed that the 102 M. morganii isolates fell into six clades, with clades 4-6 making up the majority. Core genome multi-locus sequence type analysis indicted high genomic diversity among different hosts and relatively stability (< 10 SNPs accumulated over three years) within the same host. Together with epidemiological data, isolates of four genetic clusters could be possible nosocomial transmissions. The identified 80 AMR genes belonged to 15 drug-related classes, with tet(B) gene being the most prevalent, followed by sul1, catA2, and sul2 genes. This study provided comprehensive genomic insights and AMR patterns of Morganella isolates in China, highlighting the necessity for continuous monitoring through whole genome sequencing.

Influence of Urinary Urea Concentration on Hemolytic Activity and Cytotoxicity of Uropathogenic Morganella morganii Strain

We studied the effect of urinary urea concentration on the hemolysin production and cytotoxicity of the uropathogenic Morganella morganii strain MM 190. The highest hemolytic activity of M. morganii cultivated in urine with low urea concentration (23 and 82 mmol/liter) was observed between 3rd and 4th hours of post-inoculation, while in urine with standard urea level (117 mmol/liter), the activity was observed at 5th hour of post-inoculation. Our findings indicate a correlation between this activity and the expression of the hlyA gene. Bacterial culture fluid containing hemolysin caused the death of up to 40% of urothelial cells; cytotoxicity was more pronounced against OKP-GS kidney carcinoma cells compared to T-24 bladder carcinoma cells. Hence, in urine with higher urea concentrations, hemolytic activity of bacteria was observed at later stages of growth, and this culture fluid exhibited higher cytotoxicity.

Distribution diversity and expression regulation of class 1 integron promoters in clinical isolates of Morganella morganii

Background

Morganella morganii is an emerging nosocomial opportunistic pathogen with increasing multidrug resistance. Antibiotic resistance, driven primarily by the horizontal transfer of resistance genes, has become a global health crisis. Integrons, mobile genetic elements, are now understood to facilitate the transfer of these genes, contributing to the rapid proliferation of resistant strains. Understanding the regulatory role of integrons in drug resistance gene expression is crucial for developing novel strategies to combat this pressing public health issue.

Objective

To investigate the distribution of promoter types in the variable regions of class 1 integrons isolated from clinical isolates of M. morganii and their regulatory role in the expression of downstream drug resistance gene cassettes.

Methods

Ninety seven clinical isolates of M. morganii were screened for the presence of class 1 integrons (intI1) using polymerase chain reaction (PCR). Gene cassettes within the variable regions of positive isolates were characterized, and the gene cassette promoter Pc variants and downstream auxiliary promoter P2 were identified. Enterobacterial repetitive intergenic consensus (ERIC)-PCR was employed for homology analysis. Recombinant plasmids containing different variable region promoters and gene cassettes were constructed to evaluate drug resistance genes and integrase (intI1) expression levels using reverse transcription-quantitative PCR (RT-qPCR) and antimicrobial susceptibility testing.

Results

Of the clinical isolates, 28.9% (n = 28/97) were positive for class 1 integrons. 24.7% (n = 24/97) of these isolates carried gene cassettes encoding resistance to aminoglycosides and trimethoprim. Three Pc promoter types (PcH1, PcS, and PcW) were identified, while all P2 promoters were inactive with a 14-base pair spacing between the -35 and -10 regions. ERIC-PCR analysis classified the integron-positive strains into 6 genotypes, with high consistency in promoter types and gene cassettes within each genotype. RT-qPCR and antimicrobial susceptibility testing demonstrated that strong promoters significantly enhanced the expression of downstream drug resistance gene cassettes compared to weak promoters. Additionally, RT-qPCR revealed a negative correlation between intI1 expression and Pc promoter strength.

Conclusion

Class 1 integrons are prevalent in M. morganii. The promoter types within these integrons are diverse, and promoter strength is closely linked to downstream gene cassette expression. Integron-positive strains exhibit high homology, suggesting horizontal gene transfer and dissemination in clinical settings.

A novel method for enrichment of Morganella morganii in fecal samples using designed culture medium

Morganella morganii is a gram negative, facultative anaerobic rod-shaped bacterium, commonly found in environment and in the intestine of human, mammals, and reptiles as a part of their gut microbiome. M. morganii can cause Gram-negative folliculitis, black nail infection, acute retiform purpura, fetal demise, and subdural empyema. The increasing frequency of M. morganii infections generate the need for efficient methods to enrich the presence of M. morganii in clinical samples to make its detection easier. Culturomics aims to grow and maximize the number of culturable bacteria. Different methods are followed to maximize the growth of minority population of bacteria by disrupting the growth of bacteria which are present in higher concentration. This article presents a method for selective enriching the M. morganii in human fecal samples. This method includes prior incubation of fecal microbiota in an anaerobic environment, adding supplement like fecal water to give dormant bacteria a break to become active to grow to threshold concentration, and an enrichment stage which provides the additional opportunity of growing to M. morganii on the selective medium. This method also provides an ingenuous way for augmenting the growth of fecal M. morganii species.

Antibiotic-Resistant Bacteria Dissemination in the Wildlife, Livestock, and Water of Maiella National Park, Italy

Antimicrobial resistance (AMR) is a global health concern that has been linked to humans, animals, and the environment. The One Health approach highlights the connection between humans, animals, and the environment and suggests that a multidisciplinary approached be used in studies investigating AMR. The present study was carried out to identify and characterize the antimicrobial resistance profiles of bacteria isolated from wildlife and livestock feces as well as from surface water samples in Maiella National Park, Italy. Ecological and georeferenced data were used to select two sampling locations, one where wildlife was caught within livestock grazing areas (sympatric group) and one where wildlife was caught outside of livestock grazing areas (non-sympatric group). Ninety-nine bacterial isolates from 132 feces samples and seven isolates from five water samples were collected between October and December 2019. The specimens were examined for species identification, antibiotic susceptibility and molecular detection of antibiotic resistance. Forty isolates were identified as Escherichia coli, forty-eight as Enterococcus spp., eight as Streptococcus spp. and ten as other gram-negative bacteria. Phenotypic antibiotic resistance to at least one antimicrobial agent, including some antibiotics that play a critical role in human medicine, was detected in 36/106 (33.9%, 95% CI: 25-43) isolates and multidrug resistance was detected in 9/106 isolates (8.49%, 95% CI: 3.9-15.5). In addition, genes associated with antibiotic resistance were identified in 61/106 (57.55%, 95% CI: 47.5-67) isolates. The samples from sympatric areas were 2.11 (95% CI: 1.2-3.5) times more likely to contain resistant bacterial isolates than the samples from non-sympatric areas. These data suggest that drug resistant bacteria may be transmitted in areas where wildlife and livestock cohabitate. This emphasizes the need for further investigations focusing on the interactions between humans, wildlife, and the environment, the results of which can aid in the early detection of emerging AMR profiles and possible transmission routes.