48 Monte Carlo Crescent Kyalami Business Park, Kyalami Johannesburg, 1684 South Africa www.thistle.co.za Tel: +27 (011) 463 3260 Fax to Email: + 27 (0) 86-557-2232 e-mail : [email protected]
Please read this section first
The HPCSA and the Med Tech Society have confirmed that this clinical case study, plus your routine review of your EQA reports from Thistle QA, should be documented as a “Journal Club” activity. This means that you must record those attending for CEU purposes. Thistle will not issue a certificate to cover these activities, nor send out “correct” answers to the CEU questions at the end of this case study.
The Thistle QA CEU No is: MTS-18/063.
Each attendee should claim ONE CEU point for completing this Quality Control Journal Club exercise, and retain a copy of the relevant Thistle QA Participation Certificate as proof of registration on a Thistle QA EQA.
MICROBIOLOGY LEGEND
CYCLE 43 – ORGANISM 5
Enterobacter aerogenes
Enterobacter aerogenes is a Gram-negative, oxidase negative, catalase positive, rod-shaped, nosocomial and pathogenic bacterium that causes opportunistic infections in skin and other tissues. Enterobacter aerogenes primarily causes nosocomial infections, being passed from one compromised patient to another. It is sometimes, but not always, a motile bacteria. Enterobacter aerogenes is a ubiquitous bacteria in the environment, found naturally in soil, fresh water, vegetables and human and animal feces.
Figure 1:Gram negative rod shaped Enterobacter aerogenes
Clinical significance
Most of the infections caused by E. aerogenes result from specific antibiotic treatments, venous catheter insertions, and/or surgical procedures. E. aerogenes is generally found in the human gastrointestinal tract and does not generally cause disease in healthy individuals. It has been found to
Page 1 of 3 48 Monte Carlo Crescent Kyalami Business Park, Kyalami Johannesburg, 1684 South Africa www.thistle.co.za Tel: +27 (011) 463 3260 Fax to Email: + 27 (0) 86-557-2232 e-mail : [email protected] live in various wastes, hygienic chemicals and soil. Enterobacter species, particularly Enterobacter cloacae and Enterobacter aerogenes, are important nosocomial pathogens responsible for various infections, including bacteremia, lower respiratory tract infections, skin and soft-tissue infections, urinary tract infections (UTIs), endocarditis, intra-abdominal infections, septic arthritis, osteomyelitis, and ophthalmic infections.
Risk factors
Enterobacter aerogenes is an opportunistic pathogen. Most individuals who develop an infection have an existing medical condition that makes it easier for the bacteria to grow and spread. Enterobacter aerogenes is frequently a hospital-acquired infection, especially of patients in the intensive-care unit or on mechanical ventilators. Other risk factors for infection include prior antibiotic use (this may reduce naturally occurring bacteria that compete with Enterobacter aerogenes), IVs or central lines, and burns. Enterobacter aerogenes more frequently affects newborns and the elderly. The bacteria are often part of a polymicrobial infection, sharing an infection site with other species of bacteria.
Laboratory Diagnosis
This organism is easy to isolate from clinical specimens and biochemical tests readily separate it from other members of the Enterobacteraceae family.
Table 1: Biochemical tests for Enterobacteraceae family
Figure 2: Enterobacter aerogenes on blood agar
Page 2 of 3 48 Monte Carlo Crescent Kyalami Business Park, Kyalami Johannesburg, 1684 South Africa www.thistle.co.za Tel: +27 (011) 463 3260 Fax to Email: + 27 (0) 86-557-2232 e-mail : [email protected]
Treatment
Antimicrobial treatment is appropriate for almost all infections with Enterobacter aerogenes. Beta- lactams, fluoroquinolones, aminoglycosides and TMP-SMZ can all be effective treatments. Most strains of the bacteria are resistant to one or more of these potential treatments, so the organism must be typed and tested for susceptibility before treatment begins.
Resistance to beta-lactams is common, as beta-lactamase production (an enzyme that breaks down beta-lactams) can be induced in bacteria exposed to these antibiotics. Enterobacter aerogenes also commonly develops resistance to first-, second- and third-generation cephalosporins during treatment.
References
1. https://healthyliving.azcentral.com › Diet & Nutrition › Nutrition 2. https://en.wikipedia.org/wiki/Enterobacter_aerogenes
3. Alekshun, M. N., and S. B. Levy. 1999. The mar regulon: multiple resistance to antibiotics and other toxic chemicals. Trends Microbiol. 7:410-413.[CrossRef][Medline] Questions 1. What are the characteristics of E. aerogenes? 2. Discuss the risk factors for E. aerogenes? 3. Discuss the treatment for E. aerogenes?
Page 3 of 3