In this chapter, selected infectious diseases that have significance in ocular cytology are presented. External infections such as
Chlamydia trachomatis and adenovirus were discussed in Chapter 3. Endophthalmitis may be divided clinically into endogenous (arising from systemic infection) and exogenous (arising from external sources).
BACTERIAL ENDOPHTHALMITIS
Over 90% of cases of endophthalmitis originate from bacterial sources and the majority of these are caused by gram-positive organism (
Staphylococcus sp., most commonly). [1]
m-negative organisms that are associated with endophthalmitis include
Proteus, Klebsiella sp.,
Serratia marcescens, Haemophilus spp., and
Pseudomonas aeruginosa. In endophthalmitis associated with cataract surgery,
S. epidermidis is the most commonly identified organism.[
2][
3] Other organisms that frequently cause infection include
S. aureus and
Propionibacterium acnes.[
4] In post-traumatic endophthalmitis,
Bacillus spp., are second only to
staphylococcus in incidence. After glaucoma filtering procedures,
Streptococcus is most common.[
5] Endogenous endophthalmitis is associated with intravenous drug abuse, meningitis, endocarditis, and urinary tract infections.[
6] The most common organisms isolated in endogenous endophthalmitis include
Bacillus sp.,
streptococcus sp.,
Neisseria meningitidis, S. aureus, and
H. influenzae.Cytology specimens are obtained in cases of acute endophthalmitis for culture and morphologic diagnosis. If a diagnostic tap of the aqueous or vitreous is performed, cultures, gram stain, and cytology should be requested (Figure 8-1).
In acute endophthalmitis, direct smears show numerous neutrophils and fibrin. Bacteria are best revealed on gram stain. Frequently, the aqueous aspirate is negative and a vitreous aspirate is necessary to demonstrate organism (Figures 8-2 and 8-3).
Vitrectomy may be indicated for both diagnosis and therapeutic removal of bacteria, fibrin, and necrotic material.[
7] Cytology preparations will reveal abundant acute inflammatory cells and necrotic debris (Figure 8-4). Normal structures may be removed inadvertently in a vitrectomy because intraoperative identification and separation of inflamed tissues is difficult (Figures 8-5 and 8-6).
MYCOBACTERIUM FORTUITUM
Mycobacterium fortuitum infection in the eye usually manifests as a suppurative keratitis related to trauma, including contact lens use, or an operation.[8][9][10][
11][
12] M.
fortuitum rarely infects the vitreous cavity primarily. However, corneal infection may spread to involve the vitreous. Intraocular washings demonstrate numerous intracellular acid-fast long-curving bacilli (Figure 8-7).
References:
1. Meredith TA. Clinical microbiology of infectious endophthalmitis. In: Ryan SJ, Ogden TE, Schachat AP, eds. Retina. St. Louis: C.V. Mosby, 1989;1:183-188.
2.
Ficker LA, Meredith TA, Wislson LA, Kaplan HJ, Kozarsky AM. Am J Ophthalmol 1987;03:745-748.
3.
Driebe WT Jr, Mandelbaum S, Forster RK, Schwartz LK, Culbertson WW. Ophthalmology 1986;93:442-448.
4.
Beatty RF, Fobin JB, Trousdale MD, Smith RE. Am J Ophthalmol 1986;101:114-116.
5.
Mandelbaum S, Forster RK, Gelender H, Culbertson W. Ophthalmology 1985;92:964-972.
6.
Greenwald MJ, Wohl LG, Sell CH. Surv Ophthalmol 1986;31:81-101.
7.
Ficker LA, Meredith TA, Wilson LA, Kaplan HJ. Br J Ophthalmol 1988;72:386-389.
8. Turner L, Stinson I. Mycobacterium fortuitum as a cause of corneal ulcer. Am J Ophthalmol 1965;60:329-331.
9. Levenson DS. Harrison CH. Mycobacterium fortuitum corneal ulcer. Arch Ophthalmol 1966;75:189-191.
10. Zimmerman LE, Turner L, McTigue JW. Mycobacterium fortuitum infection of cornea.Arch Ophthalmol 1969;82:596-601.
11.
Wunsh SE, Boyle GL, Leopold IH, Littman ML. Arch Ophthalmol 1969;82:602-607.
12.
Lazar M, Nemet P, Bracha R, Campus A. Am J Ophthalmol 1974;78:530-532.
