**10. Gram positive bacteria and** *Mycobacterium*

**Coagulase negative** *Staphylococcus.* Frequently keratitis associated to coagulase negative *Staphylococcus* are located in the paracentral sites or even near the limbo in patients whom have some systemic immunologic involvement like arthritis or Sjögreen syndrome. The main species isolated are *S hominis, S haemolyticus* and in all cases the bacteria came from conjunctiva flora. In all series consulted *Staphylococcus epidermidis* are the most frequent ker‐ atitis bacteria isolated [16].

**Staphylococcus aureus.** Keratitis caused by this bacterium begin as an epithelial defect, in concomitant conjunctivitis, indiabetic patients or treated with topical steroids patients, be‐ ginning as a superficial and stroma, multifocal opacity with few inflammatory cells. After two or three days without antibiotic treatment, a dense infiltrate is observed in the immedi‐ ate area below the ulcer, and it may progress in indolent form or take a rapid development with a deep and abundant secretion over the corneal surface and conjunctiva. At same time, it can be observed an important cilliary inflammatory reaction close to the ulcer, and con‐ junctiva vascularization,(Figure 4). In some patients, a sterile ulcer located in the inferior corneal zone (8 to 4 clockaround) are caused by immune reaction to dermonecrotic toxins and staphylolisin generated by *Staphylococcus aureus* blepharitis demonstrated by cultures of both; eye lids superior and inferior (Figure 5).

The corneal smears showed inflammatory cells and Gram positive intracellular or extra-cel‐ lular round bacteria (Figure 6). In a diabetic patient, the sample cultures yielded abundant colonies of *Staphylococcus aureus* in cornea and in conjunctiva samples (Figure 7).

**Figure 4.** *Staphylococcus aureus* near the limbus keratitis and cilliar reaction.

For white filamentous and melanized fungus cultures, it may be observed for its morpholo‐ gy and pigmentation, on surface and reverse of the colony and for its final identification in microcultures for his characteristics conidial forms, prepared with lactophenol blue and di‐ rect optical microscopy observation according to the Manual of Clinical Microbiology [14]

**Coagulase negative** *Staphylococcus.* Frequently keratitis associated to coagulase negative *Staphylococcus* are located in the paracentral sites or even near the limbo in patients whom have some systemic immunologic involvement like arthritis or Sjögreen syndrome. The main species isolated are *S hominis, S haemolyticus* and in all cases the bacteria came from conjunctiva flora. In all series consulted *Staphylococcus epidermidis* are the most frequent ker‐

**Staphylococcus aureus.** Keratitis caused by this bacterium begin as an epithelial defect, in concomitant conjunctivitis, indiabetic patients or treated with topical steroids patients, be‐ ginning as a superficial and stroma, multifocal opacity with few inflammatory cells. After two or three days without antibiotic treatment, a dense infiltrate is observed in the immedi‐ ate area below the ulcer, and it may progress in indolent form or take a rapid development with a deep and abundant secretion over the corneal surface and conjunctiva. At same time, it can be observed an important cilliary inflammatory reaction close to the ulcer, and con‐ junctiva vascularization,(Figure 4). In some patients, a sterile ulcer located in the inferior corneal zone (8 to 4 clockaround) are caused by immune reaction to dermonecrotic toxins and staphylolisin generated by *Staphylococcus aureus* blepharitis demonstrated by cultures of

The corneal smears showed inflammatory cells and Gram positive intracellular or extra-cel‐ lular round bacteria (Figure 6). In a diabetic patient, the sample cultures yielded abundant

colonies of *Staphylococcus aureus* in cornea and in conjunctiva samples (Figure 7).

**10. Gram positive bacteria and** *Mycobacterium*

and Larone [15].

68 Common Eye Infections

atitis bacteria isolated [16].

both; eye lids superior and inferior (Figure 5).

**Figure 4.** *Staphylococcus aureus* near the limbus keratitis and cilliar reaction.

**Figure 5.** Immune inflammatory reactions in cornea, due to *Staphylococcus aureus* toxins in a patient diagnosed with bacterial blepharitis.

**Figure 6.** *Staphylococcus* cells ingested by polymorphonuclear leukocytes in a Gram smear of bacterial keratitis. 1000 X

**Figure 7.** Culture of *Staphylococcus aureus* keratitis showing incorneal C streaks and conjunctiva sample abundant colonies, from a diabetic patient

**Streptococcus pneumonia, S viridians and S agalactiae.** Formerly named serpinginous ul‐ cer, begins in central cornea with a focal suppurative stromal infiltrate that can reach super‐ ficial spread with leading edges, and dense infiltrate below the ulcer (Figure 8), in 70% of the case, hypopyon is observed in some cases occupying 50 % or more in anterior chamber and abundant conjunctiva yellowish secretion, patients refers severe pain. In diabetic patient and treated with topical steroid, the severe inflammatory process that reaches vitreous can cause an inflammatory or infectious endophtalmitis.

In infrequent contaminated post LASIK surgeries, keratitis is originated on streptococcal conjunctivitis developed after the surgery and it is observed like white inflammatory spots in the inter-phase wound and below the corneal flap. (Figure 9)

**Figure 8.** Central, suppurative *Streptoccocus pneumoniae* keratitis in a immuno suppressed female patient.

**Figure 9.** Post LASIK *Streptococcus pneumoniae* keratitis.

In the corneal samples smears, Gram positive *diplococcus* are observed. (Figure 1), and in cul‐ tures, *Streptococcus pneumoniae* colonies are obtained(Figure 10), the presumptive identifica‐ tion test for inhibition growth with cooper compound Optoquine is shown in Figure 11

In infrequent contaminated post LASIK surgeries, keratitis is originated on streptococcal conjunctivitis developed after the surgery and it is observed like white inflammatory spots

**Figure 8.** Central, suppurative *Streptoccocus pneumoniae* keratitis in a immuno suppressed female patient.

In the corneal samples smears, Gram positive *diplococcus* are observed. (Figure 1), and in cul‐ tures, *Streptococcus pneumoniae* colonies are obtained(Figure 10), the presumptive identifica‐ tion test for inhibition growth with cooper compound Optoquine is shown in Figure 11

**Figure 10.** Abundant colonies of *Streptococcus pneumoniae* in conjunctiva and cornea samples from patient of figure

in the inter-phase wound and below the corneal flap. (Figure 9)

70 Common Eye Infections

**Figure 9.** Post LASIK *Streptococcus pneumoniae* keratitis.

9 (Left).

**Actinomycetes.** Keratitis caused by anaerobic Actinomycetes like Actinomyces israelí, A bo‐ vis or aerobic Actinomycetes classified in the genus Nocardia, Actinomadura, Gordonia, Nocardiopsis, Oerskovia, Rhodococcus, Streptomyces, Sacharomonospora, Thermmoactino‐ myces, Tsukamurella [17], are indolent and with torpid evolution, without response to topi‐ cal antibiotic like 4a generation quinolone, the traumatic and soil contaminated antecedent are considered in 30%, the infiltrate shows some dense spots in clear cornea and the corneal ulcer is above the infiltrate zone ( Figure 12), the smears reveal filamentous Gram positive bacteria (Figure 13) and the culture show yellowish-white colonies in the C strakes of the corneal sample (Figure 14) the medical topical treatment recommended are topical amikacin or sulfadiazine and oral sulfamethoxazole and trimetoprim in regular doses. [18]

**Figure 12.** Keratitis due to Nocardia in a traumatic soil contaminated, 5 days of evolution in an adolescent male.

**Figure 13.** Gram positive filamentous bacteria showing ramifications in the cornea sample (Left).

**Figure 11.** Optoquine inhibition test for *Streptococcus pneumoniae,* and Bacitracine disk without inhibition (Right).

**Figure 14.** *Nocardia asteroides* cultures from cornea sample of patient in figure 12.

**Non tuberculous Mycobacterium:***Mycobacterium chelonae, M intracelulare* are rapidly growing bacteria (7 to 8 days) and are related to low pain or indolent keratitis with torpid evolution, diffi‐ culty in diagnosis and with poor results in the treatment. The risky antecedent are corneal ero‐ sions or cornea transplant (Figure 15). The topical treatment needs long time and various antibiotics; fourth generation quinolones, amikacyn and clarytromycin. In the smears often it is observed Gram irregular and curved bacilli that in Zihel-Neelsen stain appear in a reddish color (Figure 16), and the cultures grows visible colonies in 7 days. (Figure 17)

**Figure 15.** Post-penetrate keratoplasty contaminated with *Mycobacterium chelonae*

**Figure 16.** Corneal smear Zihel-Neelsen stained, showing acid-fast bacilli (black arrow) of the patient in figure 12 1000 X (Left).

**Figure 17.** White-yellow colonies of *Mycobacterium chelonae* obtained from the sample of patient in Figure 12.
