**3.** *Corynebacterium* **species as a pathogen: Case presentations**

Case 1: In 2003, the author encountered the case of an elderly patient who had clear infec‐ tious conjunctivitis in his right eye. He had experienced mild conjunctival hyperaemia and mucopurulent discharge after cataract surgery performed 2 years before consultation (Fig. 1). He had continued to use a quinolone ophthalmic solution postoperatively, but had not undergone any ophthalmic examination. He had eye discomfort for more than 3 months. Gram staining smear of the discharge showed that many polymorphonuclear leukocytes phagocytizing Gram-positive rods (Fig. 2). Culture of the discharge sample detected quino‐ lone resistant *Corynebacterium* species, and the strain was susceptible to cephem antibiotics. Switching the quinolone ophthalmic solution to a cephem antibiotic resolved of the patient's symptoms. The author determined this to be a clear case of conjunctivitis due to *Corynebacte‐ rium* species. Thereafter, the author encountered a large number of cases of *Corynebacterium* conjunctivitis in geriatric patient as well as several cases of *Corynebacterium* keratitis in pa‐ tients who underwent keratoplasty. Thus, in 2012, *Corynebacterium* species still appear to be pathogens of the ocular surface.

**Figure 2.** Gram stain of the discharge sample from case 1, original magnification ×1000 Gram-positive rods shaped bacteria in palisade- and 'I, or V' letter-shaped formations were found within polymorphonuclear neutrophil leuko‐

Ocular Infections Caused by *Corynebacterium* Species

http://dx.doi.org/10.5772/56214

77

Case 2: Figures 3 A & B show an ocular surface of a diabetic young man. He had intractable filamentous keratitis after 2 vitrectomies. When he was referred to the author's clinic, a mox‐ ifloxacin ophthalmic solution has been prescribed for more than 6 months (from the perio‐ perative stage of the first vitrectomy). After the diagnosis of infectious blepharoconjunctivitis with mucopurulent yellowish discharge, it was determined that the blepharoconjunctivitis may have caused swelling of the eyelid, and the swollen eyelid parti‐ ally induced intractable filamentous keratitis. Analysis of a smear of the discharge showed a large number of polymorphonuclear leukocytes and Gram-positive rod-shaped bacteria in palisade- and 'I, V, or W' letter-shaped arrangements (Fig. 4). *Corynebacterium* species were identified in the culture of the discharge by using a simple, commercially available identifi‐ cation kit (BBL Crystal, BD, Japan, Tokyo). The author also isolated *Corynebacterium* species on a sheep blood agar plate from the discharge and identified the causative agent as *Coryne‐ bacterium macginleyi* on the basis of its biochemical characters tested by API-Coryne (bioMér‐ ieux SA, Lyon, France). The minimum inhibitory concentration (MIC) of moxifloxacin and ceftriaxone for the strain (tested by E-test®, bioMérieux SA, Lyon, France) was >256μg/mL and 2 μg/mL, respectively. Switching moxifloxacin to topical cephmenoxim led to rapid im‐

It is currently no exaggeration to say that *Corynebacterium* species are among the major pathogens responsible for chronic conjunctivitis, especially in geriatric patients. These pathogens can also cause infectious keratitis in patients who are immune-compromised [3-5]. All such conditions may be triggered, when the bacterial flora of the ocular surface are disturbed, by opportunistic infections. Endophthalmitis caused by *Corynebacterium* species is

provement of blepharoconjunctivitis and filamentous keratitis (Fig. 5).

cytes.

**Figure 1.** Infectious conjunctivitis occurred in case 1. A mild infectious conjunctivitis was found.

**Lipophilicity**: Few *Corynebacterium* species generally have high lipophilicity. In vitro, they can be easily become unculturable if the final concentration of Tween 80 (polysorbate 80) in the medium is slightly different from the optimal concentration. Presumably, this is the rea‐ son why particular *Corynebacterium* species prefer the ocular surfaces as these are area where fatty acids are always present because they are secreted from the meibomian gland. This re‐ quirement may also explain why *Corynebacterium*-induced endophthalmitis is very rare.

Case 1: In 2003, the author encountered the case of an elderly patient who had clear infec‐ tious conjunctivitis in his right eye. He had experienced mild conjunctival hyperaemia and mucopurulent discharge after cataract surgery performed 2 years before consultation (Fig. 1). He had continued to use a quinolone ophthalmic solution postoperatively, but had not undergone any ophthalmic examination. He had eye discomfort for more than 3 months. Gram staining smear of the discharge showed that many polymorphonuclear leukocytes phagocytizing Gram-positive rods (Fig. 2). Culture of the discharge sample detected quino‐ lone resistant *Corynebacterium* species, and the strain was susceptible to cephem antibiotics. Switching the quinolone ophthalmic solution to a cephem antibiotic resolved of the patient's symptoms. The author determined this to be a clear case of conjunctivitis due to *Corynebacte‐ rium* species. Thereafter, the author encountered a large number of cases of *Corynebacterium* conjunctivitis in geriatric patient as well as several cases of *Corynebacterium* keratitis in pa‐ tients who underwent keratoplasty. Thus, in 2012, *Corynebacterium* species still appear to be

**3.** *Corynebacterium* **species as a pathogen: Case presentations**

**Figure 1.** Infectious conjunctivitis occurred in case 1. A mild infectious conjunctivitis was found.

pathogens of the ocular surface.

76 Infection Control

**Figure 2.** Gram stain of the discharge sample from case 1, original magnification ×1000 Gram-positive rods shaped bacteria in palisade- and 'I, or V' letter-shaped formations were found within polymorphonuclear neutrophil leuko‐ cytes.

Case 2: Figures 3 A & B show an ocular surface of a diabetic young man. He had intractable filamentous keratitis after 2 vitrectomies. When he was referred to the author's clinic, a mox‐ ifloxacin ophthalmic solution has been prescribed for more than 6 months (from the perio‐ perative stage of the first vitrectomy). After the diagnosis of infectious blepharoconjunctivitis with mucopurulent yellowish discharge, it was determined that the blepharoconjunctivitis may have caused swelling of the eyelid, and the swollen eyelid parti‐ ally induced intractable filamentous keratitis. Analysis of a smear of the discharge showed a large number of polymorphonuclear leukocytes and Gram-positive rod-shaped bacteria in palisade- and 'I, V, or W' letter-shaped arrangements (Fig. 4). *Corynebacterium* species were identified in the culture of the discharge by using a simple, commercially available identifi‐ cation kit (BBL Crystal, BD, Japan, Tokyo). The author also isolated *Corynebacterium* species on a sheep blood agar plate from the discharge and identified the causative agent as *Coryne‐ bacterium macginleyi* on the basis of its biochemical characters tested by API-Coryne (bioMér‐ ieux SA, Lyon, France). The minimum inhibitory concentration (MIC) of moxifloxacin and ceftriaxone for the strain (tested by E-test®, bioMérieux SA, Lyon, France) was >256μg/mL and 2 μg/mL, respectively. Switching moxifloxacin to topical cephmenoxim led to rapid im‐ provement of blepharoconjunctivitis and filamentous keratitis (Fig. 5).

It is currently no exaggeration to say that *Corynebacterium* species are among the major pathogens responsible for chronic conjunctivitis, especially in geriatric patients. These pathogens can also cause infectious keratitis in patients who are immune-compromised [3-5]. All such conditions may be triggered, when the bacterial flora of the ocular surface are disturbed, by opportunistic infections. Endophthalmitis caused by *Corynebacterium* species is

Figure 3 Anterior segments of case 2.

A: Moderate blepharoconjunctivitis and yellowish mucopurulent discharge were found. B: Corneal erosion with filamentous keratitis was found. **Figure 3.** Anterior segments of case 2. Moderate blepharoconjunctivitis, yellowish mucopurulent discharge, and cor‐ neal erosion with filamentous keratitis were found.

very rare. Although *C. macginleyi* is the common *Corynebacterium* species to be isolated from the ocular surface [6, 7], it remains unclear whether *C. macginleyi* is the major species respon‐ sible for ocular infections because cases caused by other species have been documented as well [5].
