Although occasionally regarded as rather worrisome pathogens,Enterobacter species are no necessarily all bad. Not often a problemin healthy and balanced individuals, they are opportunistic pathogens in peoplewith precarious immune systems, specifically in hospitals whereby infectioncontrol has damaged down. Meaning to man Benefits Enterobacter cloacae has actually been offered in organic control of plant diseases(notably the seed-rotting oomycete Pythium ultimum).Transgenic (aargh!?) E. Cloacae have been offered to control insectpests top top mulberry pipeline .

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Harm

Enterobacter infections room becoming more common in intensive care. Theyare mainly uncovered where:Infection regulate is negative (little hand-washing)- many infections are obtained through cross-transmission< J epidemic Dis 2001 Jul 15;184(2):211-214>. Ready transmission occurs -for example, rapid disinfection the rectalthermometers through 80% alcohol does NOT avoid transmission ofE. Cloacae.

Substantially endangered patients are existing - the an extremely young, the an extremely old, and, especially, those with serious underlying disease, such as neoplasms, or immune suppression including human immunodeficiency virus epidemic - typically in the later stages the the disease.

Enterobacter epidemic has additionally been traced to contaminated albuminconcentrates (yet an additional reason no to usage albumin),prefilled saline syringes,multidose vials and contaminatedinfant formulae (in the tin), v consequent necrotising enterocolitis.Total parenteral nutrition solutions have been contaminated duringpreparation.Haemodialysis equipments with defective waste-handling ports have alsobeen responsible for haematogenous infection.Strains have even been found that can grow in drink containingmethylparaben (and will even grow in concentration of 3000mg/L)! Enterobacter meningitis in adults has beenreported adhering to neurosurgery, maybe consequent top top the usualpredisposing causes!

Mechanisms that injury

These have been poorly studied. Watch for some data ~ above aerobactin production, haemagglutinins (mannose-sensitive),and resistance to serum bactericidal activity. A haemolytic leukotoxinhas to be reported .

Identification and features

A member the the household "Enterobacteriaceae" (but no the "type genus" - thisdubious honour belongs to Escherichia), Enterobacter can more-or-lessbe established if friend encounter large lactose-fermenting swarms of Gram negativerods, that space either increased or mucoid . The only essential confounding bugis Klebsiella, i m sorry is comparable (and very closely related) - admittedly,Hafnia alvei is similar, but is rarely a cause of an illness inman. Serratia marcescens doesn"t ferment lactose.

We deserve to often identify Enterobacter from Klebsiella by seeing whetherthe organism is motile - if it is, it need to be Enterobacter (althoughsome are immotile). Enterobacter can additionally decarboxylate ornithine,something Klebsiella can not do.

Enterobacter strains are mostly fimbriate and also slime-forming.(Also citrate +ve, generate gas indigenous glucose, ferment sucrose, arabinose,mannitol, melibiose, raffinose, rhamnose, trehalose, and also xylose. Mostare DNAse, indole, H 2 S and also phenylalanine deaminase negative).

Media

Eosin methylene blue (EMB) agar is selective because that gram an unfavorable bacteria.Enterobacter and Klebsiella form large mucoid colonies that space pinkto purple due to the fact that of your lactose fermentation. Castle don"t have themetallic sheen that E. Coli.On MacConkey agar lactose fermentation outcomes in a red colour.

Here space some images off the web:

Pinkish nests of Enterobacter aerogenes farming on MacConkey agarFig 1.

Mucoid-looking virtually iridescent Enterobacter aerogenes cultivation on EMB agarFig 2.

Escherichia coli cultivation on MacConkey agar. Note greenish sheenFig 3.

Fig 1. Mirrors the red colour emerged on MacConkey agar, Fig 2.the organism cultivation on EMB agar, which friend may comparison with Fig 3.where you can see the greenish sheen the E. Coli. The recommendations section gives the internet sources of the pictures!

Species, Nomenclature and also Relatives

There are several Enterobacter species, but E. Cloacae and also toa lesser degree, E. Aerogenes,are the commonest pathogens. E. Sakazakii (which creates bright yellowcolonies) is less common, yet a nasty reason of neonatal sepsis, andespecially, meningitis, with brain abscesses, significant ventriculitis, andhydrocephalus as a constant consequence.The quite unusual "E. Agglomerans" is now known as Pantoea agglomerans (also once called Erwinia milletiae) - itmay reason infection in ICU and has also been invoked together the cause for"cotton fever" - encountered wherein intravenous drug abusers filter theirheroin v cotton!(Other varieties are E. Amnigenus, asburiae,cancerogenus* <=taylorae =cancerogena =CDC enteric group 19>, dissolvens, gergoviae,hormaechei <=CDC enteric team 75>, intermedius <=intermedium>,kobei <=NIH team 21>, nimipressuralis, and also pyrinus*, possibly also "cowanii" <=NIH team 42>; *=plant pathogens).

Different types of Enterobacter are differentiated by theirability to ferment particular sugars, and also possession of arginine dihydrolase,lysine and ornithine decarboxylase.

Treatment

Carbapenems room at existing probably the treatment of choice, althoughcefepime might be used. Quinolone sensitivity is variable, and also resistancemay develop during treatment (this can likewise occur with carbapenems).Some organisms are sensitive come co-trimoxazole.

Note that some advocate mix chemotherapy because that E. Cloacaeinfection.

Resistance

Resistance to everything apart from carbapenems (imipenem, meropenem)and perhaps quinolones is common. Part recommend the quinolonesnot be offered owing to emergence of resistance during therapy.In fact, resistance come carbapenems may likewise emerge. Fads andrates the resistance differ greatly between antibiotics

Do no usefirst, second or 3rd generation cephalosporins together they space oftenineffective, and also resistance frequently appears, specifically in unitswhere cross-infection is common, and use of this agents is widespread.Cefepime resistance is not at current a significant problem, so this isanother option. (Cefepime and cefpirome resistance is currently well-documented,related to enormous production that a modified cephalosporinase ).

Amp-C (stably derepressed) cephalosporinases are commonly present.

ESBL resistance may be transferred from Enterobacter to E. Coli

E. Cloacae resistance to carbapenems has actually been reported related toa mix of:loss that a significant porin;(As both beta lactams and fluoroquinolones enter Enterobacter speciesthrough their F porin, loss of this protein can be meant to conferresistance) a group-1 beta lactamase mopping up any little amounts of medicine that obtain through;

Occasional resistance to carbapenems might be as result of production the zincmetallo-proteinases (e.g. IMP-1), or seldom "Ambler class A" beta lactamases(E. Cloacae stress, overload NOR-1).

As expected, mutations in DNA gyrase confer fluoroquinoloneresistance - a single point mutation is enough.

Cautions

Avoid the use of first, 2nd or third-generation cephalosporins,as these may predispose come Enterobacter infections. Hand-washingis still the many important way to protect against Enterobacter infection.

References

Many referrals are installed in the HTML message (Click see | Sourcein her browser).

We briefly disputed Enterobacter in ours antibiotic therapy in ICU web-page.

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The pictures above came from:The new York University institution of medication courseware on transmittable diseases(Visit http://endeavor.med.nyu.edu/courses/microbiology/courseware/infect-disease/Gram_Neg_Bacilli5.html) whichis an impressive and extremely well-illustrated page on identification of Gram-negative bacilli.