although cataract surgery is highly effective and relatively safe , owing to the enormous numbers , even uncommon surgical complications could be potentially harmful for many patients .
endophthalmitis is one of the most serious complications of cataract surgery , affecting around 0.1% of the cases , and often resulting in severe visual impairment .
this complication often occurs sporadically , and in such situations , the common source of infection may be due to the conjunctival flora of the patient .
the major pathogens are coagulase - negative staphylococci ( 70% ) , staphylococcus aureus ( 10% ) , streptococci ( 9% ) , other gram - positive cocci , including enterococci and mixed bacteria ( 5% ) , and gram - negative bacilli ( 6% ) . the fact that gram - positive bacteria cause > 95% of the cases reflect the usual pathogenesis , i.e. contamination of the aqueous humor with skin bacteria flora during surgery . however , unusual germs causing the infection are sometimes isolated and should be suspected in cases with a non - typical evolution .
a 65 year - old female patient was urgently admitted to a hospital emergency room 48 hours after a cataract surgery , referring to red eye and vision decrease in the operated eye . visual acuity on
the initial exam was hands movement in the right eye and 20/40 in the left eye .
ophthalmological examinations showed conjunctival injection in the right eye , hypopyon , 3 + cells in anterior chamber and severe vitreitis with no fundus view .
she was hospitalized and 23 g pars plana vitrectomy was immediately performed and a vitreous biopsy was taken for culture .
additionally , she was treated with topical ocular applications of fortified tobramycin ( 15 mg / ml ) and ceftazidime ( 50 mg / ml ) every hour and with intravitreal injections of vancomycin ( 1 mg/0.1 ml ) and ceftazidime ( 2 mg/0.1 ml ) after the vitrectomy and 2 and 4 days after operation . intravenous antibiotics ( 1 g of vancomycin ) were also administered twice a day , 500 mg ceftazidime/12 hours , as well as the administration of systemic corticosteroid after 24 hours ( oral prednisone 1 mg / kg / day ) .
because of the bad evolution after 36 hours , systemic treatment was then empirically changed to linezolid 600 mg and moxifloxacin 400 mg , twice a day .
vitreous was cultured in blood agar , chocolate agar ( incubated 48h in microaerophilic conditions ) and thioglycollate broth ; and was isolated in an all media pure culture of gram - positive cocci , forming white colonies and catalase positive , which was identified by the microbiology laboratory as rothia mucilaginosa through matrix - assisted laser desorption / ionization - time of flight ( maldi - tof , bruker daltonics , bruker corporation , billerica , ma , usa ) .
antimicrobial sensitivity test was done by the kirby - bauer method , being susceptible to all antibiotics tested ( penicillins , cephalosporins , fluoroquinolones , erythromycin , clindamycin , and tetracycline ) .
although this organism was susceptible to the empirical antibiotics used , a bad clinical response was observed with increasing hypopyon . during the next days ,
pain , conjunctival injection , hypopyon and anterior chamber reaction worsened and a large vitreous abscess was observed .
r. mucilaginosa , formerly called stomatococcus mucilaginosus , is part of the normal flora of the upper respiratory tract and oral cavity .
it was reclassified into a new genus belonging to the family micrococcaceae in 2000 , based on 16s rrna sequencing .
gram staining reveals non - spore - forming , encapsulated gram - positive cocci that can appear in pairs , tetrads , or irregular clusters .
it is a facultative anaerobic bacterium , which grows well on most nonselective media and in standard blood culture systems . on sheep blood and chocolate agar , the bacterium forms clear to gray / white , non - hemolytic , mucoid or sticky colonies , which adhere to the agar surface
. it can be difficult to distinguish it from coagulase - negative staphylococci , micrococci , and streptococci based on the catalase test result .
its inability to grow in 6.5% sodium chloride and its ability to hydrolyze gelatin and esculin distinguish it from species of staphylococcus , micrococcus , and enterococcus genera .
identification from automatic methods should correlate with phenotypic identification ; otherwise , genetic sequencing may be required to identify this organism .
recently , infections in immunocompetent hosts have been described in various organ systems , including patients with pneumonia , bacteremia , and septic arthritis .
it has been reported in two cases of eye infection , a postoperative endophthalmitis in a 91-year - old male and a keratitis in vitamin a deficiency .
the known risk factors for this infection are immunosuppression , parenteral drugs , alcoholism , diabetes , neoplastic and valvular disease , but our patient did not present any of these .
none of the reported patients with ocular infections caused by r mucilaginosa had these risk factors , so it is possible that in - ocular infections could be irrelevant . in this sense , the source of the infection in our case remains unknown . as mentioned , r. mucilaginosa is part of the normal flora of the upper respiratory tract and oral cavity but has not been isolated in normal conjunctival flora . in our opinion self - contamination of
the patient could be the origin of the infection , but contamination of eye drops used in the perioperative period with r. mucilaginosa is also a possibility .
unfortunately , a search of r. mucilaginosa in the eye drops was not performed when the patient was admitted in the hospital .
it would have been of interest to demonstrate the origin of the contamination . however , it was reported that r. mucilaginosa is able to colonize a foreign body as a vascular catheter .
the organism s ability to produce a biofilm , similar to other gram - positive bacteria , is believed to be a key pathogenic mechanism .
the physical protective layer provided by the biofilm presumably facilitates adhesion of the organisms to devices and renders them relatively refractory to medical therapy .
to our knowledge , this is the second case report of r. mucilaginosa endophthalmitis after a cataract surgery and the first after phacoemulsification .
it is increasingly recognized as an emerging opportunistic pathogen associated with eye infections and it may be difficult to identify .
physicians should be aware of this organism when treating nonresponding patients infected with gram - positive bacteria in ocular infections .
 we aimed at reporting the first case of rapidly progressive acute postoperative endophthalmitis after phacoemulsification cataract surgery in an immunocompetent patient caused by rothia mucilaginosa . 
 an immunocompetent patient manifested endophthalmitis signs 48 hours after an uncomplicated cataract surgery by phacoemulsification . 
 a bacteria of the family micrococcaceae was cultured in the vitreous biopsy , namely r. mucilaginosa . 
 the patient did not show a favorable clinical response after vitrectomy and systemic , intravitreal , and topical fortified antibiotics . 
 the patient s eye was very painful , and consequently , it deemed necessary to perform an evisceration . 
 r. mucilaginosa may be an aggressive etiologic agent for postoperative endophthalmitis . although the isolated r. mucilaginosa was susceptible to empirical treatment , it was impossible to control the infection with standard treatment , probably due to its ability to create a biofilm around the intraocular lens . 
Introduction
Case Report
Discussion
Conclusions