**15. Endophthalmitis due to coinfection**

months or years and are difficult to treat with diamine and biguanide drugs in developing

Some of the bacteria mechanisms within *Acanthamoeba* spp. have been described. Scheid *et. al*., using an *in vitro* model with electronic microscopy, showed the cycle of a coccoid-like organism in the free-living amoebae *Vannella* spp. The coccoid microorganism is a phagocyte and is transported by phagocytic vacuoles through the cytosol until reaching the amoeba nucleus where the microorganism proliferates and is released by rupture of the host mem‐ brane. In the beginning of the life cycle, coccoid microorganisms are phagocytes for other amoeba [34]. In addition, endosymbiont bacteria can replicate only into the amoeba cytosol, can break the cells, and can be ingested by neighboring amoeba [35]. However, the intrusion of bacteria into *Acanthamoeba polyphaga* has consequences for both microorganisms. A protein bellows the amoeba that adheres to the surface of *Legionella pneumophila*. The authors discussed the possibility that the liberation of the bacteria from the amoeba integrates amoeba antigens in its membrane. However, *Pseudomonas aeruginosa* and its liberated products kill *Acanthamoe‐ ba* spp. [30, 32, 36]. Another study showed that endosymbiont bacteria favor the growth of different species of *Acanthamoeba*, and all microorganisms isolated from contact lens care

*Acanthamoeba* spp. by itself causes severe inflammation in the cornea. Aggressive keratolysis or sclerokeratitis is a common complication. The most frequently reported symptoms are pain, photophobia, and tearing [38]. The association of *Acanthamoeba* spp. with bacteria or a fungus presents a coinfection that can mimic bacterial, fungal, or herpetic keratitis, which can delay the time to diagnosis and increase the pathogenicity of the *Acanthamoeba* spp. infection.

Several molecular methods and electronic microscopy have facilitated the observation of bacteria within *Acanthamoeba*, including *Pseudomonas aeruginosa*, *Listeria monocytogenes*, *Mycobacterium* spp., *Escherichia coli*, *Legionella pneumophila*, *Chlamydia* spp., and *Aeromonas* spp. They are also capable of producing keratitis themselves [30, 32, 39, 40, 41]. In addition, there are many reports in the literature of cases of *Acanthamoeba* and bacteria coinfection isolated

This type of coinfection is uncommon. Similar to bacteria, fungi have a complex relationship with *Acanthamoeba* spp. and generate lesions that can be confused with bacterial or herpetic keratitis; the prognosis is discouraging. In all cases reported, penetrating keratoplasty was performed. These coinfections require immediate and aggressive treatment with antifungal

Conjunctivitis is the most common eye infection in the world. Usually, the normal microbiota in the conjunctiva participates in infectious diseases of the ocular surface, and it has been

from patients with or without contact lens-associated keratitis [39, 42, 43, 44].

countries (chlorhexidine and polyhexamethylene biguanide, respectively) [33].

solutions contained numerous trophozoites [37].

128 Advances in Common Eye Infections

**13.** *Acanthamoeba* **and fungi**

and antiamoebic drugs [45, 46, 47, 48, 49].

**14. Conjunctivitis due to coinfection**

Endophthalmitis is an inflammatory intraocular reaction and is the most important compli‐ cation for an ophthalmologist following surgery, trauma, and between others. The common presentation of the clinical picture is characterized by pain and decreased vision. As previously discussed in the section on keratitis due to bacteria and fungus coinfections, endophthalmitis due to coinfection can be confused with single bacterial or fungal infections. Thus, to facilitate successful interventions, the microorganisms responsible must be identified and antimicrobial sensitivity examined. Studies of several large series have shown the frequency of endophthal‐ mitis due to bacteria and fungus and bacteria and bacteria coinfections.

Depending on patients' geographic region, consecutive case studies have found various incidence rates for this coinfection ranging from 2.4 % to 50 % [56, 57, 58, 59].

The most commonly isolated pathogens are Gram-positive cocci bacteria with filamentous fungi [60, 61]. However, Gram-negative or Gram-positive bacilli related to fungi are also responsible for endophthalmitis [60, 61, 62].
