Journal of Pediatric Ophthalmology and Strabismus

Short Subjects 

Acute Conjunctivitis Caused by Ewingella americana

Sofia Maraki, MD

Abstract

The first case of Ewingella americana conjunctivitis in an otherwise healthy child is reported. Cultures of the conjunctival purulent exudate taken from both eyes grew E. americana. The infection resolved completely after successful treatment with amoxicillin/clavulanate. E. americana should be considered a rare but potential pathogen causing conjunctivitis.

From the Department of Clinical Microbiology, Parasitology, Zoonoses and Geographical Medicine, University Hospital of Heraklion, Crete, Greece.

The author has no financial or proprietary interest in the materials presented herein.

Address correspondence to Sofia Maraki, MD, Department of Clinical Microbiology, Parasitology, Zoonoses and Geographical Medicine, University Hospital of Heraklion, 71 110 Heraklion, Crete, Greece. E-mail: sofiamaraki@in.gr

Received: May 02, 2012
Accepted: August 22, 2012
Posted Online: September 25, 2012

Abstract

The first case of Ewingella americana conjunctivitis in an otherwise healthy child is reported. Cultures of the conjunctival purulent exudate taken from both eyes grew E. americana. The infection resolved completely after successful treatment with amoxicillin/clavulanate. E. americana should be considered a rare but potential pathogen causing conjunctivitis.

From the Department of Clinical Microbiology, Parasitology, Zoonoses and Geographical Medicine, University Hospital of Heraklion, Crete, Greece.

The author has no financial or proprietary interest in the materials presented herein.

Address correspondence to Sofia Maraki, MD, Department of Clinical Microbiology, Parasitology, Zoonoses and Geographical Medicine, University Hospital of Heraklion, 71 110 Heraklion, Crete, Greece. E-mail: sofiamaraki@in.gr

Received: May 02, 2012
Accepted: August 22, 2012
Posted Online: September 25, 2012

Introduction

Ewingella, previously classified as enteric group 40 by the Enteric Section of the Centers for Disease Control and Prevention, is a genus of the family Enterobacteriaceae and was first described in 1983 by Grimont et al.1E. americana is the only species in the genus. This microorganism has rarely been found in clinical samples. In most cases, the pathogenic significance of the organism has not been established.1 Recently, some case studies have documented the clinical importance and the pathogenic potential of E. americana in humans.2–7

This article reports the first case of conjunctivitis in an immunocompetent child caused by E. americana.

Case Report

A 3-year-old boy presented with bilateral injection and a moderate amount of purulent discharge. The symptoms had appeared 2 days before his admission. There was no pain or fever and there was no history of any recent infection or injury prior to onset of symptoms. The child did not take any medication and no other family members had a similar condition.

Ocular examination confirmed purulent conjunctivitis and a swab was taken from both eyes for bacterial culture. Microscopic examination of Gram-stained smears of the exudate revealed many white cells and Gram-negative rods. The samples were cultured in routine bacteriological media. After overnight incubation at 37°C, a Gram-negative, lactose-fermenting rod that was oxidase negative and catalase positive grew in pure culture (Figure 1). The isolate was identified by the Vitek 2 and the API 20E systems (BioMérieux, Marcy L’ Etoile, France) as E. americana. The antimicrobial susceptibility testing of the isolate was performed by the E-test method and showed susceptibilities against ampicillin, amoxicillin/clavulanic acid, cephalosporins, imipenem, aminoglycosides, quinolones, tetracyclines, chloramphenicol, and trimethoprim/sulfamethoxazole, but resistance only to cephalothin (Table 1). The patient was prescribed tobramycin 0.3% ophthalmic solution but did not comply with the recommendations of the attending physician. The next day, symptoms persisted and treatment was switched to oral amoxicillin/clavulanate (45 mg/kg twice a day). The condition subsided over the next 5 days and the patient was well at follow-up. Cultures showed that the organism had been eradicated from the eyes.

Gram-negative small rods of Ewingella americana in culture (Gram stain, original magnification ×1,000).

Figure 1. Gram-negative small rods of Ewingella americana in culture (Gram stain, original magnification ×1,000).

In Vitro Susceptibility Testing of the Ewingella americana Isolate

Table 1: In Vitro Susceptibility Testing of the Ewingella americana Isolate

Discussion

Acute bacterial conjunctivitis in children is a significant healthcare concern all over the world.8 Beyond the neonatal period, acute conjunctivitis is twice as likely to be due to bacteria than viruses. Weiss et al. reported that almost 78% of 95 patients with conjunctivitis who were assessed by a pediatric ophthalmologist had a bacterial cause.9Haemophilus infl uenzae is the most frequently isolated organism, followed by Streptococcus pneumoniae and Branhamella catarrhalis. The role of Staphylococcus species in the pathogenesis of conjunctivitis is controversial because they have been isolated from the conjunctivae of children with conjunctivitis and from those of asymptomatic children at equal rates.8 Other less common causes of purulent conjunctivitis in children are Neisseria gonorrhoeae and Neisseria meningitidis. E. americana has not been previously isolated from children with conjunctivitis. However, two cases of E. americana conjunctivitis have been described in adults.6,7 This is the first documented case of E. americana conjunctivitis in Greece with an undefined source of the infection. We speculate that the child could have been contaminated by an environmental source. The microorganism can survive in water and citrate solutions and has been also isolated from mushrooms and mollusks.10–13

Our patient had neither any identifiable risk factor for conjunctivitis nor any type of immuno-suppression.

Although conjunctivitis is a self-limited disease, treatment with antibiotics is warranted for bacterial eradication and for a more rapid clinical cure.8 Our patient was successfully treated with amoxicillin/clavulanate.

The majority of E. americana isolates showed uniform susceptibility to all antibiotic classes tested with the exception of the first-generation cephalosporins in which the microorganism is naturally resistant. This is also the case of the current isolate. However, additional resistance phenotypes have emerged, including beta-lactams, aminoglycosides, and tetracyclines.7,10 Stock et al. studied the susceptibility of 20 E. americana isolates to several antibiotics and found that resistance to beta-lactams was attributed to the production of an inducible AmpC beta-lactamase.14 Resistance to multiple antibiotics has been detected in only two cases.4,5

E. americana may be considered an infrequent but potential cause of conjunctivitis. Because of the increasing resistance to antibiotics, culture of the conjunctival exudates and susceptibility testing of the isolated pathogens are helpful for the choice of the appropriate therapy.

References

  1. Grimont PA, Farmer JJ, Grimont F, Asbury MA, Brenner DJ, Deval C. Ewingella americana gen.nov., sp.nov., a new Enterobac-teriaceae isolated from clinical specimens. Ann Microbiol (Paris). 1983;134A:39–52.
  2. Devreese K, Claeys G, Verschraegen G. Septicemia with Ewingella americana. J Clin Microbiol. 1992;30:2746–2747.
  3. Maertens J, Delforge M, Vandenberghe P, Boogaerts M, Verhaegen J. Catheter-related bacteremia due to Ewingella americana. Clin Microbiol Infect. 2001;7:103–104. doi:10.1046/j.1469-0691.2001.00195.x [CrossRef]
  4. Pound MW, Tart SB, Okoye O. Multidrug resistant Ewingella americana: a case report and review of the literature. Ann Pharmacother. 2007;41:2066–2070. doi:10.1345/aph.1K398 [CrossRef]
  5. Bukhari SZ, Hussain WM, Fatani MI, Ashshi AM. Multi-drug resistant Ewingella americana. Saudi Med J. 2008;29:1051–1053.
  6. Heizman WR, Michel R. Isolation of Ewingella americana from a patient with conjunctivitis. Eur J Clin Microbiol Infect Dis. 1991;10:957–959. doi:10.1007/BF02005452 [CrossRef]
  7. Da Costa PS, Tostes MM, de Carvalho Valle LM. A case of keratoconjunctivitis due to Ewingella americana and a review of unusual organisms causing external eye infections. Braz J Infect Dis. 2000;4:262–267.
  8. Teoh DL, Reynolds S. Diagnosis and management of pediatric conjunctivitis. Pediatr Emerg Care. 2003;19:48–55. doi:10.1097/00006565-200302000-00014 [CrossRef]
  9. Weiss A, Brinser JH, Nazar-Stewart V. Acute conjunctivitis in childhood. J Pediatr. 1993;122:10–14. doi:10.1016/S0022-3476(05)83479-1 [CrossRef]
  10. Pien FD, Bruce AE. Nosocomial Ewingella americana bacteremia in an intensive care unit. Arch Intern Med. 1986;146:111–112. doi:10.1001/archinte.1986.00360130133018 [CrossRef]
  11. McNeil MM, Davis BJ, Solomon SL, et al. Ewingella americana: recurrent pseudobacteremia from a persistent environmental reservoir. J Clin Microbiol. 1987;25:498–500.
  12. Inglis PW, Peberdy JF. Isolation of Ewingella americana from the cultivated mushroom, Agaricus bisporus. Curr Microbiol. 1996;33:334–337. doi:10.1007/s002849900124 [CrossRef]
  13. Muller HE, Fanning GR, Brenner DJ. Isolation of Ewingella americana from molluscs. Curr Microbiol. 1995;31:287–290. doi:10.1007/BF00314581 [CrossRef]
  14. Stock I, Sherwood KJ, Wiedemann B. Natural antibiotic susceptibility of Ewingella americana strains. J Chemother. 2003;15:428–441.

In Vitro Susceptibility Testing of the Ewingella americana Isolate

Antibiotic MIC (μg/mL) Interpretation
Ampicillin 4 S
Amoxicillin/clavulanic acid 1.5 S
Cefalotin ⩾ 64 R
Cefuroxime 4 S
Cefaclor 4 S
Cefotaxime 0.094 S
Ceftriaxone 0.094 S
Cefepime 0.032 S
Imipenem 0.25 S
Gentamicin 0.064 S
Amikacin 0.19 S
Tobramycin 0.064 S
Netilmicin 0.125 S
Ciprofloxacin 0.012 S
Levofloxacin 0.032 S
Moxifloxacin 0.125 S
Chloramphenicol 4 S
Tetracycline 1 S
TMP/SMX 0.047 S

10.3928/01913913-20120918-01

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