Enterobacter aerogenes and Enterobacter cloacae; versatile bacterial pathogens confronting antibiotic treatment

Abstract

Enterobacter aerogenes and E. cloacae have been reported as important opportunistic and multiresistant bacterial pathogens for humans during the last three decades in hospital wards. These Gram-negative bacteria have been largely described during several outbreaks of hospital-acquired infections in Europe and particularly in France. The dissemination of Enterobacter sp. is associated with the presence of redundant regulatory cascades that efficiently control the membrane permeability ensuring the bacterial protection and the expression of detoxifying enzymes involved in antibiotic degradation/inactivation. In addition, these bacterial species are able to acquire numerous genetic mobile elements that strongly contribute to antibiotic resistance. Moreover, this particular fitness help them to colonize several environments and hosts and rapidly and efficiently adapt their metabolism and physiology to external conditions and environmental stresses. Enterobacter is a versatile bacterium able to promptly respond to the antibiotic treatment in the colonized patient. The balance of the prevalence, E. aerogenes versus E. cloacae, in the reported hospital infections during the last period, questions about the horizontal transmission of mobile elements containing antibiotic resistance genes, e.g., the efficacy of the exchange of resistance genes Klebsiella pneumoniae to Enterobacter sp. It is also important to mention the possible role of antibiotic use in the treatment of bacterial infectious diseases in this E. aerogenes/E. cloacae evolution.

Dissemination of multiresistant Enterobacter cloacae isolates producing OXA-48 and CTX-M-15 in a Spanish hospital

“…Isolates overproducing AmpC are also resistant to broad-spectrum cephalosporins. Furthermore, E. cloacae has the ability to acquire additional resistance mechanisms, including plasmid-encoded extendedspectrum ␤-lactamases (ESBLs) and carbapenemases [1]. Phenotypic detection of ESBL production may be difficult since it can be masked by overexpression of AmpC.…”

“…Phenotypic detection of ESBL production may be difficult since it can be masked by overexpression of AmpC. Some E. cloacae isolates may also exhibit permeability defects due to the absence of porins or porin mutations, further increasing the minimum inhibitory concentrations (MICs) of ␤-lactams and carbapenems, particularly ertapenem [1].…”

“…Enterobacter cloacae is an opportunistic pathogen frequently involved in nosocomial infections [1]. This enterobacterial species is intrinsically resistant to aminopenicillins, amoxicillin/clavulanic acid (AMC) and cephalosporins of early generations owing to a chromosomally encoded AmpC ␤-lactamase.…”

Indigenous Oil Degrading Bacteria: Isolation, Screening and Characterization

“…The highest level of resistance towards ampicillin indicated its previous exposures to antibiotics and also indicated the well spread resistance of microorganisms towards ampicillin and related drugs. Resistance of Enterobacter cloacae towards ampicillin is also reported [17].…”

Vacuum Sealing Drainage Treatment of Multi-Drug–Resistant Enterobacter Cloacae Wound Infection in a Diabetic Patient: A Case Report and Review of the Literature

“…have increasingly emerged as a cause of hospital-acquired infections [7]. These gram-negative bacteria have been reported to be important causes of opportunistic and multi-drug-resistant infections in humans during the last three decades [8]. About 10% of patients with Enterobacter infections are non-responsive to treatment [9].…”