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Enterobacter aerogenes

Industry of interest: Healthcare

Classification: Bacteria

Microbiology: Enterobacter aerogenes is a Gram-negative rod-shaped microorganism from the Enterobacteriaceae family. It is commonly responsible for infections in hospitals; however it has become a cause for concern in community infections (Sanders and Sanders, 1997).


Habitat and transmission: E. aerogenes forms part of the endogenous human gastrointestinal (GI) microflora. It also resides in soil, water and in dairy products. Generally infections arise from the patients’ own flora; however cross-infection can occur via the hands of healthcare workers, during insertion of medical devices and in surgical procedures (Sanders and Sanders, 1997). Contaminated surfaces may play a role in the transmission of Enterobacter, particularly during outbreaks (Otter, 2010).

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Treatment and antibiotic resistance: Enterobacter species are notorious for their drug resistance, which is thought to have been amplified by the use of broad spectrum cephalosporins in hospitals (Giamarellou, 2005). E. aerogenes uses three mechanisms of resistance; inactivating enzymes, alteration of drug targets and alteration of the ability of drugs to enter and or accumulate in its cells (Sanders and Sanders, 1997). All Enterobacter species are part of an emerging group of highly antibiotic resistant Gram-negative bacteria with extended-spectrum β -lactamases (ESBLs) (Giamarellou, 2005). The susceptibility of Enterobacter strains varies widely but “older” antibiotics such as colistin may be required to treat multidrug-resistant strains (Sanders and Sanders, 1997). Some of the antibiotics that E. aerogenes is known to be resistant to include β -lactam antibiotics, aminoglycosides and quinolones.

Prevention and control: The options for control of E. aerogenes are extremely limited as most infections arise from an endogenous source and many strains are now highly antibiotic resistant (Sanders and Sanders, 1997). Important practices such as hand-hygiene, environmental decontamination, hospital surveillance of antibiotic resistance, controlled use of antibiotics (particularly 3rd generation cephalosporins) and aseptic insertion of catheters and implanted devices will reduce transmission of the organism (Giamarellou, 2005). Some have also suggested the use of targeted prophylactic antibiotic treatments, however there is a risk of increasing antibiotic resistance associated with this practice and it is not in general use (Sanders and Sanders, 1997).


Enterobacter is a frequent cause of infection in immunocompromised individuals, low birth weight and premature babies, and those with serious underlying health conditions. It has frequently been implicated in urinary tract infections (UTIs), skin and soft tissue infections, respiratory infections, GI infections, adult meningitis, wound infections and bacteraemia (Sanders and Sanders, 1997). Particular risk factors for E. aerogenes infection include prolonged hospital stay, intravenous catheter use, invasive surgical procedures and previous antibiotic usage.


Giamarellou H. (2005) Multidrug resistance in Gram-negative bacteria that produce extended-spectrum beta-lactamases (ESBLs). Clin Microbiol Infect. 11(Suppl 4): 1-16.

Otter JA, Yezli S, Schouten MA, van Zanten AR, Houmes-Zielman G, Nohlmans-Paulssen MK (2010) Hydrogen peroxide vapor decontamination of an intensive care unit to remove environmental reservoirs of multidrug-resistant gram-negative rods during an outbreak. Am J Infect Control 2010. 38: 754-756.

Sanders W.E. Jr. And Sanders C.C. (1997) Enterobacter spp: pathogens poised to flourish at the turn of the century. Clin Microbiol Rev. 10(2): 220-241.

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