Molecular characterization and potential sources of aqueous humor bacterial contamination during phacoemulsification with intraocular lens implantation in dogs

Abstract

Bacterial contamination of the anterior chamber during cataract surgery is one of the main responsible for endophthalmitis postoperative. Phacoemulsification is a less invasive technique for cataract treatment, although it does not exclude the possibility of contamination. In this study, bacterial contaminants of aqueous humor collected pre- and post-phacoemulsification with intraocular lens implantation (IOL) of twenty dogs were identified. As the conjunctival microbiota constitute a significant source of anterior chamber contamination, bacterial isolates from aqueous humor were genetically compared with those present in the conjunctival surface of the patients. Three dogs presented bacterial growth in both aqueous humor and conjunctival surface samples. Bacterial isolates from these samples were grouped according to their genetic profiles by repetitive-element PCR (rep-PCR) and their representatives were identified by 16S rRNA sequencing. Isolates from conjunctival surface were identified as Enterobacter spp., Staphylococcus spp. and S. aureus; and from aqueous humor samples as Enterobacter spp., Pantoea spp., Streptococcus spp. and Staphylococcus spp., respectively in decreasing order of prevalence. According to the rep-PCR analysis, 16.6% of Enterobacter spp. isolates from conjunctival surface were genetically similar to those from aqueous humor. The rest of isolates encountered in aqueous humor were genetically distinct from those of conjunctival surface. The significant genetic diversity of bacterial isolates found in the aqueous humor samples after surgery denoted the possibility of anterior chamber contamination during phacoemulsification by bacteria not only from conjunctival surface but also from different sources related to surgical environment.

The effect of postoperative oral antibiotic therapy on the incidence of postoperative endophthalmitis after phacoemulsification surgery in dogs: 368 eyes (1997–2010)

“…The cases in this report developed more than a week postoperatively, analogous to what some authors in the human literature designate “chronic post-phacoemulsification endophthalmitis” ( Durand, 2013 ); other authors describe cases occurring within 6 weeks of surgery as “acute” and those occurring more than 6 weeks after surgery as “delayed onset” ( Miller et al, 2005 ). Most cases of endophthalmitis following phacoemulsification probably occur following introduction of infectious agents from the conjunctiva and eyelid margins ( Sherwood et al, 1989 ; Tervo et al, 1999 ; Liesegang, 2001 ; Ledbetter, Millichamp & Dziezyc, 2004 ), although Lacerda et al demonstrated that sources of contamination other than the ocular surface do occur in canine phacoemulsification ( Lacerda et al, 2018 ). The third patient affected with endophthalmitis in this report deserves particular attention.…”

“…The rate of post-cataract extraction endophthalmitis ranges from 0.012% to 0.56% in the human literature ( Liesegang, 2001 ; Ciulla, Starr & Masket, 2002 ; Kamalarajah et al, 2004 ; Li et al, 2004 ; Taban et al, 2005 ; Wejde et al, 2005 ; Ou & Ta, 2006 ; Rosha et al, 2006 ; Cao et al, 2013 ; Rudnisky, Wan & Weis, 2014 ), with two large meta-analyses reporting average rates of 0.134% ( n = 6,686,169; Cao et al, 2013 ) and 0.128% ( n = 3,140,560; Taban et al, 2005 ). Rates from 0–1.4% have been published in dogs ( Sigle & Nasisse, 2006 ; Johnstone & Ward, 2005 ; Azoulay et al, 2013 ; Ledbetter, Spertus & Kurtzman, 2018 ; Lacerda et al, 2018 ). The presumed sources of ocular infection in humans are the eyelids and conjunctival surface ( Speaker & Menikoff, 1991 ) and risk factors include advanced age, immunosuppressive comorbidities ( e.g ., diabetes mellitus), and intraoperative complications ( Sengillo et al, 2020 ); the same are presumed to be true for veterinary patients ( Ledbetter, Spertus & Kurtzman, 2018 ).…”

Systematic Review and Meta-Analysis of the Occurrence of ESKAPE Bacteria Group in Dogs, and the Related Zoonotic Risk in Animal-Assisted Therapy, and in Animal-Assisted Activity in the Health Context

“…All papers were published from 2002 to 2018. The number of dogs sampled ranged between 20 [108] and 136 [95], for a total of 450 dogs in the seven papers included. The prevalent type of specimens was represented by urine samples [98] and ocular tissues [108], and then by ocular, rectal, and oral swabs [82,95,109].…”

“…The number of dogs sampled ranged between 20 [108] and 136 [95], for a total of 450 dogs in the seven papers included. The prevalent type of specimens was represented by urine samples [98] and ocular tissues [108], and then by ocular, rectal, and oral swabs [82,95,109]. In addition, Lobetti and colleagues [99] has been performed their study on intravenous catheters.…”

“…Percentage values of Enterobacter spp. in dog urine were 2.0% [98]; in eye swabs they ranged from 4.2% [82] to 16.6% [108], while in oral swabs the values were 1.6% [109]; finally, in rectal swabs the values equal to 21.3% [95]. All studies included for the evaluation of the presence of Enterobacter spp.…”