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.

Emergence of blaCTX-M-15 Gene and Its Transferability in Enterobacter spp. Isolated From the Hospitals of Tehran, Iran

“…In recent years, ESBL production among these isolates is becoming a major clinical concern because of its ability to develop resistance to several classes of antimicrobial agents and has high potential for transmission of resistance to other bacterial species (16). In the current study, the most prevalent clinical Enterobacter species was E. cloacae (78.2 %) that showed the important role of this species in human infections, which was in agreement with other reports (17)(18)(19)(20).…”

Enterobacter cloacae Complex Isolates Harboring bla NMC-A or bla IMI -Type Class A Carbapenemase Genes on Novel Chromosomal Integrative Elements and Plasmids

“…The isolates harboring bla IMI types were more widely distributed among multiple clusters. It has been hypothesized that the higher prevalence of E. hormaechei and cluster III isolates in a nosocomial environment is due to niche adaptation (21). The paucity of Enterobacter isolates harboring bla NMC-A/IMI types from hospitalized patients may reflect poor adaptation to this environment for these genetic clusters and hence a barrier to a more widespread distribution here, such as outbreaks.…”

“…Despite this, however, bla NMC-A/IMI -type genes have rarely been found outside Enterobacter, which is likely due to their rarity overall, the low likelihood of being mobilized to a plasmid (via insertion sequences), and potential plasmid instability in other genera, as putatively shown for pIMI-5 in E. coli. In previous studies of isolates from human infections using hsp60 partial gene sequencing for identification (2), E. hormaechei isolates in clusters VI and VIII and E. cloacae isolates in cluster III were the main species identified (21)(22)(23)(24). More recently, MLST of MDR isolates has identified several clonal groups which cluster with E. hormaechei ( Fig.…”

Resistance patterns and integron cassette arrays of Enterobacter cloacae complex strains of human origin

“…Hi-Fi Taq polymerase and other PCR reagents were also purchased from Novazym. Primers Hsp60-F and Hsp60-R were used to amplify a portion of hsp60 by PCR according to Morand et al (2009). The PCR products were purified using ExoSAP-IT (Affymetrix) and sequenced in a 3130xl Genetic Analyzer (Applied Biosystems).…”

“…hormaechei subsp. oharae' and E. cloacae cluster III are the species most frequently recovered from clinical specimens (Hoffmann et al, 2005;Morand et al, 2009). Moreover, E. hormaechei was reported to have caused an epidemic outbreak (Paauw et al, 2009).…”