Dataset Information

Specific distribution within the Enterobacter cloacae complex of strains isolated from infected orthopedic implants.

ABSTRACT: Bacteria belonging to the Enterobacter genus are frequently isolated from clinical samples but are unusual causative agents of orthopedic implant infections. Twelve genetic clusters (clusters I to XII) and one sequence crowd (sequence crowd xiii) can be distinguished within the Enterobacter cloacae nomenspecies on the basis of hsp60 sequence analysis, and until now, none of these clusters could be specifically associated with a disease. In order to investigate if specific genetic clusters would be involved in infections of orthopedic material, two series of bacterial clinical isolates identified as E. cloacae by routine phenotypic identification methods were collected either from infected orthopedic implants (n = 21) or from randomly selected samples of diverse anatomical origins (control; n = 52). Analysis of the hsp60 gene showed that genetic clusters III, VI, and VIII were the most frequent genetic clusters detected in the control group, whereas cluster III was poorly represented among the orthopedic implant isolates (P = 0.006). On the other hand, E. hormaechei (clusters VI and VIII), but not cluster III, is predominantly associated with infections of orthopedic implants and, more specifically, with infected material in the hip (P = 0.019). These results support the hypothesis that, among the isolates within the E. cloacae complex, E. hormaechei and hsp60 gene sequencing-based cluster III are involved in pathogenesis in different ways and highlight the need for more accurate routine Enterobacter identification methods.

SUBMITTER: Morand PC

PROVIDER: S-EPMC2725656 | biostudies-literature | 2009 Aug

REPOSITORIES: biostudies-literature

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Specific distribution within the Enterobacter cloacae complex of strains isolated from infected orthopedic implants.

Morand Philippe C PC Billoet Annick A Rottman Martin M Sivadon-Tardy Valérie V Eyrolle Luc L Jeanne Luc L Tazi Asmaa A Anract Philippe P Courpied Jean-Pierre JP Poyart Claire C Dumaine Valérie V

Journal of clinical microbiology 20090610 8

Bacteria belonging to the Enterobacter genus are frequently isolated from clinical samples but are unusual causative agents of orthopedic implant infections. Twelve genetic clusters (clusters I to XII) and one sequence crowd (sequence crowd xiii) can be distinguished within the Enterobacter cloacae nomenspecies on the basis of hsp60 sequence analysis, and until now, none of these clusters could be specifically associated with a disease. In order to investigate if specific genetic clusters would ...[more]

PMID: 19515837

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Project description:Enterobacter cloacae complex (Ecc) species are widely distributed opportunistic pathogens mainly associated with humans and plants. In this study, the genomes of clinical isolates including E. hormaechei, E. kobei, and E. ludwigii and non-clinical isolate including E. nimipressuralis were analysed in combination with the genome of E. asburiae by using the reference strain E. cloacae subsp. cloacae ATCC 13047; the Ecc strains were tested on artificial sputum media (ASM), which mimics the host, to evaluate T6SS genes as a case study. All five Ecc strains were sequenced in our lab. Comparative genome analysis of the Ecc strains revealed that genes associated with the survival of Ecc strains, including genes of metal-requiring proteins, defence-associated genes and genes associated with general physiology, were highly conserved in the genomes. However, the genes involved in virulence and drug resistance, specifically those involved in bacterial secretion, host determination and colonization of different strains, were present in different genomic regions. For example, T6SS accessory and core components, T4SS, and multidrug resistance genes/efflux system genes seemed vital for the survival of Ecc strains in various environmental niches, such as humans and plants. Moreover, the ASM host-mimicking growth medium revealed significantly high expression of T6SS genes, including PrpC, which is a regulatory gene of the T6SS, in all tested Ecc strains compared to the control medium. The variations in T6SS gene expression in ASM vs. control showed that the ASM system represents a simple, reproducible and economical alternative to animal models for studies such as those aimed at understanding the divergence of Ecc populations. In summary, genome sequencing of clinical and environmental Ecc genomes will assist in understanding the epidemiology of Ecc strains, including the isolation, virulence characteristics, prevention and treatment of infectious disease caused by these broad-host-range niche-associated species.

Project description:Matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) is commonly used by clinical microbiology laboratories to identify pathogens, despite some limitations of the technique. The Enterobacter cloacae complex (ECC) taxonomy has recently been expanded, leading to uncertain identification of some species within the ECC when commercial MALDI-TOF MS is used. This technique is especially unsuited in the case of E. hormaechei, the main species responsible for infections and one of the most prone, within the ECC, to acquire antibiotic resistance. Hence, rapid and reliable identification at the species level could improve patient management. Here, we evaluated the performance of the Bruker Microflex MALDI-TOF MS instrument to identify ECC isolates using two databases and algorithms in comparison to the hsp60 gene sequencing reference method: the Bruker database included in the MALDI Biotyper software and an extensive online database coupled to an original Mass Spectrometric Identification (MSI) algorithm. Among a panel of 94 ECC isolates tested in triplicate, the online database coupled to MSI software allowed the highest rate of identification at the species level (92%) compared to the MALDI Biotyper database (25%), especially for the species E. hormaechei (97% versus 20%). We show that by creating a database of MALDI-TOF reference spectral profiles with a high number of representatives associated with the performant MSI software, we were able to substantially improve the identification of the E. cloacae complex members, with only 8% of isolates misidentified at the species level. This online database is available through a free online MSI application (https://msi.happy-dev.fr/). IMPORTANCE Creation of a database of MALDI-TOF reference spectral profiles with a high number of representatives associated with the performant MSI software enables substantial improvement in identification of E. cloacae complex members. Moreover, this online database is available through a free online MSI application (https://msi.happy-dev.fr/).

Dataset Information

Specific distribution within the Enterobacter cloacae complex of strains isolated from infected orthopedic implants.

Publications

Specific distribution within the Enterobacter cloacae complex of strains isolated from infected orthopedic implants.

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