Aeromonas hydrophila RIT668 and Citrobacter portucalensis RIT669-Potential Zoonotic Pathogens Isolated from Spotted Turtles

The curious case of the rare Citrobacter pasteurii isolated from an endangered primate in Brazil

The genus Citrobacter comprises clinically important human pathogens but has been less frequently associated with wildlife infections. Citrobacter pasteurii was first identified as causing human diarrhea and remains rarely documented. In this study, a Gram-negative bacterial strain, named A318, was identified as causing diarrhea in a black lion tamarin. This strain was biochemically identified as Trabulsiella guamensis, a species of unusual nature, and was submitted to whole-genome characterization. Curiously, phylogenomic analysis showed that A318 strain belonged to the genus Citrobacter, with confirmation of the species C. pasteurii by average nucleotide identity (99.02 %) and digital DNA-DNA hybridization (93.80 %) analyzes. Cases of misidentification of C. pasteurii as Citrobacter youngae were detected and corrected in this study. In addition to the genome sequence of the type strain of C. pasteurii, only two others from the Australian cockle and Portuguese silver gull are publicly available. Single nucleotide polymorphism differences among all C. pasteurii indicated a highly diverse population. No acquired antimicrobial resistance genes and plasmid replicons were found. Therefore, our findings emphasize the importance of gold-standard methods for accurate identification and underscores the importance of continued surveillance and research to mitigate the risks posed by zoonotic and zooanthroponotic pathogens.

Emergence of an Extensive Drug Resistant Citrobacter portucalensis Clinical Strain Harboring bla SFO-1, bla KPC-2, and bla NDM-1

Background

To explore the plasmid characteristics and transfer mechanisms of an extensive drug resistant (XDR) clinical isolate, Citrobacter portucalensis L2724hy, co-producing bla SFO-1, bla NDM-1, and bla KPC-2.

Methods

Species confirmation of L2724hy was achieved through 16S rRNA sequencing and Average Nucleotide Identity (ANI) analysis. Antimicrobial susceptibility testing (AST) employed the agar dilution and micro broth dilution methods. Identification of resistance genes was carried out by PCR and whole-genome sequencing (WGS). Essential resistance gene locations were verified by S1 nuclease pulsed-field gel electrophoresis (S1-PFGE) and southern hybridization experiments. Subsequent WGS data analysis delved into drug resistance genes and plasmids.

Results

The confirmation of the strain L2724hy as an extensive drug-resistant Citrobacter portucalensis, resistant to almost all antibiotics tested except polymyxin B and tigecycline, was achieved through 16S rRNA sequencing, ANI analysis and AST results. WGS and subsequent analysis revealed L2724hy carrying bla SFO-1, bla NDM-1, and bla KPC-2 on plasmids of various sizes. The uncommon ESBL gene bla SFO-1 coexists with the fosA3 gene on an IncFII plasmid, featuring the genetic environment IS26-fosA3-IS26-ampR-bla SFO-1-IS26. The bla NDM-1 was found on an IncX3 plasmid, coexisting with bla SHV-12, displaying the sequence IS5-IS3000-IS3000-Tn2-bla NDM-1-ble-trpF-dsbD-cutA-gros-groL, lacking ISAa125. The bla KPC-2 is located on an unclassified plasmid, exhibiting the sequence Tn2-tnpR-ISKpn27-bla KPC-2-ISKpn6-korC. Conjugation assays confirmed the transferability of both bla NDM-1 and bla KPC-2.

Conclusion

We discovered the coexistence of bla SFO-1, bla NDM-1, and bla KPC-2 in C. portucalensis for the first time, delving into plasmid characteristics and transfer mechanisms. Our finding highlights the importance of vigilant monitoring of drug-resistance genes and insertion elements in uncommon strains.

Bullfrogs (Lithobates catesbeianus) as a Potential Source of Foodborne Disease

In Mexico, bullfrogs (Lithobates catesbeianus) are produced as gourmet food. However, bullfrogs can be carriers of pathogens because the frogs' preferred living conditions occur in stagnant water. The present study aimed to identify bacteria that cause foodborne diseases or are associated with human diseases. For molecular identification, based on the sequential analysis by 16S rRNA or rpoD was conducted on all isolates obtained from bullfrog. A total of 91 bacterial isolates were obtained from bullfrogs; 14 genera and 23 species were identified, including Acinetobacter johnsonii 16.5%; Aeromonas media 14.3%; Aeromonas veronii 13.2%; Providencia rettgeri 7.7%; Citrobacter freundii 6.6%; Aeromonas caviae 4.4%; Aeromonas hydrophila and Elizabethkingia ursingii 3.3%; Pseudomonas stutzeri, Raoultella ornithinolytica, and Shewanella putrefaciens 2.2%; Acinetobacter guillouiae, Acinetobacter pseudolwoffii, Citrobacter portucalensis, Citrobacter werkmanii, Edwardsiella anguillarum, Klebsiella michiganensis, Kluyvera intermedia, Kocuria rosea, Myroides odoratimimus, Myroides odoratus, Proteus sp., and Proteus hauseri 1.1%. In this study, 49.4% of the isolates obtained cause foodborne disease, 19.8% are bacteria that play an important role in the spoilage of food, 5.5% of isolates have nosocomial significance, 13.2% of bacteria are considered to be pollutants of the ecosystem, and in the case of A. salmonicida and Edwardsiella anguillarum (12.1%) to have a negative impact on aquaculture. Acinetobacter pseudolwoffii and Citrobacter portucalensis have not been reported to cause disease. Lastly of these isolates, 97.8% (89/91) can cause disease by food consumption or by direct contact for immunocompromised persons. The presence of these bacteria in bullfrogs represents a significant problem for human health. There is evidence that these microorganisms are pathogenic and frogs may also be reservoirs.

Detection and Antimicrobial Resistance of Enterobacteriaceae other than Escherichia Coli in Raccoons from the Madrid Region of Spain

Introduction

Raccoons are an invasive alien species widely distributed in the Madrid region of Spain. These animals can carry a variety of enteric bacteria with associated antimicrobial resistance, which can infect humans and livestock. However, to our knowledge, the presence of non-E. coli Enterobacteriaceae in raccoons has not been previously studied.

Material and Methods

We conducted a study to examine the species distribution of Enterobacteriaceae isolates other than E. coli, as well as their antimicrobial resistance, in the faeces of 83 raccoons in the Madrid region.

Results

We detected 12 Enterobacteriaceae isolates other than E. coli belonging to seven different species: Citrobacter freundii (1 isolate), Citrobacter gillenii (3 isolates), Citrobacter murliniae (1 isolate), Citrobacter portucalensis (2 isolates), Enterobacter hormaechei subsp. hoffmannii (1 isolate), Hafnia paralvei (2 isolates) and Raoultella ornithinolytica (2 isolates). These isolates were found in 7 of the 83 (8.4%) animals studied. To our knowledge, this study is the first report of the presence of non-E. coli Enterobacteriaceae in raccoon faeces. All isolates but one were resistant to at least one of the 14 antimicrobials tested. Resistance to ampicillin (83.3%), amoxicillinclavulanic acid (50%) and cefoxitin (33.3%) was the most frequent.

Conclusion

Our study indicates that raccoons are a potential source of infection with Enterobacteriaceae other than E. coli for humans and livestock in the Madrid region.

Emergence of Extensively Drug-Resistant ST170 Citrobacter portucalensis with Plasmids pK218-KPC, pK218-NDM, and pK218-SHV from a Tertiary Hospital, China

The objective of this study is to characterize the molecular mechanism of a clinical carbapenem-resistant Citrobacter portucalensis strain K218, which coproduces KPC and NDM carbapenemases. K218 was isolated from a patient's blood sample in a Chinese tertiary hospital. Carbapenemases were detected by the immunocolloidal gold technique. The MIC values were determined by VITEK2. Whole-genome sequencing was performed on K218 and sequence data were analyzed using phylogenetics and extensive genomic comparison. This study reveals that K218 contains a single 5.08 Mb chromosome (51.8% GC content) and four plasmids, pK218-KPC (106 Kb), pK218-NDM (111 Kb), pK218-SHV (191 Kb), and pK218-NR (5 Kb). Twenty-nine types of antibiotic resistance genes were carried on K218, including blaKPC-2 harbored on pK218-KPC and blaNDM-1 harbored on pK218-NDM. Detailed comparison of related plasmids of pK218-KPC, pK218-NDM, and pK218-SHV showed that they shared similar conserved backbone regions, respectively. Comprehensive annotation revealed large accessory modules were recombined on the genome of K218. Further analysis speculated that mobile genetic elements bearing abundant resistance genes facilitated the formation of these accessory modules. In conclusion, this study provides an in-depth understanding of the genomic characterization of K218, an extensively drug-resistant C. portucalensis strain coproducing NDM and KPC carbapenemase. To the best of our knowledge, this is the first report of C. portucalensis strain coharboring blaKPC-2 and blaNDM-1 from the clinical setting. IMPORTANCE This is the first report of extensively drug-resistant C. portucalensis harboring both blaKPC-2 and blaNDM-1. This study will not only extend the understanding of the structural dissection of plasmids and chromosomes carried in C. portucalensis, but also expand knowledge of the genetic environment of the blaKPC-2 and blaNDM-1 genes. blaKPC-2 and blaNDM-1 genes have been suggested to facilitate the propagation and persistence of their host bacteria under different antimicrobial selection pressures. Large accessory regions carrying blaKPC-2 and blaNDM-1 genes have become hot spots for transposition and integration, and their structural variation and evolution should receive attention. The multidrug-resistant plasmids pK218-KPC, pK218-NDM, and pK218-SHV with several multidrug resistance regions and the chromosome cK218 with two novel transposons Tn7410 and Tn7411 contribute to the formation of extensively drug-resistant C. portucalensis.