Antibiotic susceptibility of conjunctival bacterial isolates from refractive surgery patients

Culture positivity and distribution of the conjunctival sac bacteria in the perioperative period of corneal refractive surgery

The objective of this study was to investigate the culture positivity and distribution of the conjunctival sac bacteria in the perioperative period of corneal refractive surgery. The selected time points of the perioperative period included before the use of antibiotic eye drops, before eye wash (after the use of antibiotic eye drops), after eye wash, and immediately after surgery. Conjunctival specimens obtained at the four time points were cultured to detect the positivity and distribution of bacteria. Before prophylactic antibiotic eye drops were administered, 49 eyes (50%) had positive bacterial culture results, with 45 isolates (91.8%) identified as Staphylococcus epidermidis. The culture positivity rates of the conjunctival sac specimens before eye wash, after eye wash, and immediately after surgery were 19.4%, 3.1%, and 4.1%, respectively. The difference was significant before and after the use of antibiotics and before and after eye wash (both P < 0.001). Staphylococcus epidermidis was the major pathogen in the conjunctival sac before corneal refractive surgery, and the culture positivity rate of the conjunctival bacteria was higher in males. Sixteen of 37 eyes (43.2%) with contact lenses had positive culture results, compared to 33 of 61 eyes (54.1%) without contact lenses (P > 0.05). The judicious preoperative use of antibiotic eye drops combined with the surgical sterile eye wash procedure maximised the removal of conjunctival sac bacteria. Skilled surgical manipulations generally did not increase the risk of infection.

Evaluation of the effects of mono or combined use of topical antiglaucomatous drops on conjunctival flora and antibiotic susceptibility

PURPOSE

To evaluate the effects of mono or combined use of topical antiglaucomatous drops (AGD) on conjunctival flora and antibiotic susceptibility.

METHODS

The study group consisting of 84 glaucoma patients using AGDs and 32 healthy controls were evaluated. Groups were formed according to the use of 1, 2 and 3 AGDs. A swab was taken from the conjunctival sac from each patient and cultures were made. Patients with conjunctival hyperemia were classified according to their appearance.

RESULTS

The mean age was 58.61 ± 14.55 years. Conjunctival culture positivity was 84.37%, 89.28% and 90.6% according to the use of 1, 2, and 3 AGDs, respectively, and it was 93.75% in the control group. Staphylococcus hominis (S. hominis) was statistically significantly higher in all glaucoma patients compared to healthy volunteers (p = .030). S. hominis was significantly higher especially in those using 2 (42.85%) and 3 (50%) AGDs, compared to those who received mono treatment (31.25%). Candida spp. was also significantly higher in glaucoma patients (p = .039). In patients with conjunctival hyperemia in glaucoma patients, the most common two bacteria were S. hominis (55.5%) and Staphylococcus epidermidis (S. epidermidis) (33%), respectively. In the relationship between isolated bacterial species and conjunctival hyperemia grades, Bacillus spp. (p = .013) was statistically significant.In glaucoma patients, norfloxacin and erythromycin resistance were found to be statistically significantly higher compared to the control group (p = .01).

CONCLUSION

Considering the statistically significant increase in isolates in all glaucoma patients, we suggest that more care should be taken in terms of infection in surgical procedures planned for glaucoma patients.

Antibiotic resistance in ocular bacterial infections: an integrative review of ophthalmic chloramphenicol

INTRODUCTION

Chloramphenicol is a broad-spectrum antibiotic widely used for treating ophthalmic infections, but concerns about rising bacterial resistance to chloramphenicol have been observed due to its frequent use as an over-the-counter medication. This review assessed the common ophthalmic bacterial pathogens, their chloramphenicol resistance mechanisms, and rates of drug resistance.

METHODS

PubMed and Google Scholar databases were searched for relevant publications from the years 2000 to 2022, bordering on ophthalmic bacterial infections, chloramphenicol susceptibility profiles, and drug resistance mechanisms against chloramphenicol. A total of 53 journal publications met the inclusion criteria, with data on the antibiotic susceptibility profiles available in 44 of the reviewed studies, which were extracted and analyzed.

RESULTS

The mean resistance rates to chloramphenicol from antibiotic susceptibility profiles varied between 0% and 74.1%, with the majority of the studies (86.4%) showing chloramphenicol resistance rates below 50%, and more than half (23 out of 44) of the studies showed resistance rates lower than 20%. The majority of the publications (n = 27; 61.4%) were from developed nations, compared to developing nations (n = 14; 31.8%), while a fraction (n = 3; 6.8%) of the studies were regional cohort studies in Europe, with no country-specific drug resistance rates. No pattern of cumulative increase or decrease in ophthalmic bacterial resistance to chloramphenicol was observed.

CONCLUSIONS

Chloramphenicol is still active against ophthalmic bacterial infections and is suitable as a topical antibiotic for ophthalmic infections. However, concerns remain about the drug becoming unsuitable in the long run due to some proof of high drug resistance rates.

Distribution and Diversity of Ocular Microbial Communities in Diabetic Patients Compared with Healthy Subjects

PURPOSE

The aim of this study was to identify differences in the major (core vs. variable) microbial genera of human subjects with and without diabetes.

METHODS

Bacterial 16S rRNA genes obtained from conjunctival swabs of 19 healthy subjects and 30 diabetic patients were sequenced using the Illumina MiSeq platform, and the sequencing data were analyzed using QIIME 1.9.1. To elucidate the microbial diversity in the ocular surface (OS), test programs from various bioinformatics domains were used.

RESULTS

Diversity index and rarefaction analysis showed that the microbial community of the diabetic patients was more diverse than that of the healthy subjects. Proteobacteria, Firmicutes, Actinobacteria, Cyanobacteria and Bacteroidetes were the dominant taxa present in the OS, and there was a significant difference in the relative abundance of the bacterial phyla between the diabetic patients and control subjects. Proteobacteria were more abundant in the diabetic group, whereas Firmicutes was more abundant in the control group. Analysis of bacterial taxa at the genus level showed that the core microbiome of diabetic patients comprised Acinetobacter, Burkholderia, Sphingomonas, and Ralstonia, whereas that of the controls comprised Bradyrhizobiaceae, Staphylococcus, Corynebacterium, Pseudomonas, Novosphingobium, Neisseriaceae, and Acinetobacter.

CONCLUSIONS

There was a significant difference in the microbial community composition between diabetic patients and healthy subjects. A high abundance of Acinetobacter in the OS of diabetic patients may arise from the unique characteristics of the OS compared with those of other organ surfaces.

Antibiotic susceptibility profiles of ocular and nasal flora in patients undergoing cataract surgery in Taiwan: an observational and cross-sectional study

OBJECTIVE

To investigate the conjunctival and nasal flora and the antibiotic susceptibility profiles of isolates from patients undergoing cataract surgery.

DESIGN

Observational and cross-sectional study.

SETTING

A single-centre study in Taiwan.

PARTICIPANTS

128 consecutive patients precataract surgery.

PRIMARY AND SECONDARY OUTCOME MEASURES METHODS

Conjunctival and nasal cultures were prospectively obtained from 128 patients on the day of cataract surgery before instillation of ophthalmic solutions in our hospital. Isolates and antibiotic susceptibility profiles were identified through standard microbiological techniques. Participants were asked to complete a questionnaire on healthcare-associated factors.

RESULTS

The positive culture rate from conjunctiva was 26.6%, yielding 84 isolates. Coagulase-negative Staphylococci were the most commonly isolated organisms (45.2%), and 35% of staphylococcal isolates were methicillin-resistant. Among staphylococcal isolates, all were susceptible to vancomycin, and 75%-82.5% were susceptible to fluoroquinolones. Methicillin-resistant isolates were significantly less susceptible than their methicillin-sensitive counterparts to tobramycin, the most commonly used prophylactic antibiotic in our hospital (28.6% vs 69.2%; p=0.005). The positive culture rate from nares for Staphylococcus aureus was 21.9%, and six isolates were methicillin-resistant. No subjects had S. aureus colonisation on conjunctiva and nares simultaneously. There were no associated risk factors for colonisation of methicillin-resistant Staphylococci. CONCLUSION: The most common conjunctival bacterial isolate of patients undergoing cataract surgery was coagulase-negative Staphylococci in Taiwan. Because of predominant antibiotic preferences and selective antibiotic pressures, Staphylococci were more susceptible to fluoroquinolones but less to tobramycin than in other reports. Additionally, methicillin-resistant Staphylococci exhibited co-resistance to tobramycin but not to fluoroquinolones.

Positive bacterial culture in conjunctival sac before cataract surgery with night stay is related to diabetes mellitus

Background

The aim of this study is to elucidate background clinical factors in patients with positive bacterial culture for the conjunctival sac before cataract surgery in Japan.

Methods

Retrospective review was made on medical records of 576 consecutive patients who underwent conjunctival sac culture before cataract surgery with night stay at a hospital in 2 years from January 2013 to December 2014. In the patients with sequential bilateral surgeries, the data were chosen for bacterial culture in the eye which had earlier surgery. The age at surgery ranged from 33 to 100 years (mean, 76.7 years). Clinical factors, analyzed in relation with positive or negative bacterial culture, included the sex, the age, the presence of hypertension or diabetes mellitus, history of cancer, and history of hospital-based surgery at other specialties.

Results

Bacterial culture of the conjunctival sac was positive in 168 patients while negative in 408 patients. In multiple regression analysis, the positive bacterial culture was related with the older age (P = 0.01), the presence of diabetes mellitus (P = 0.004), and the history of hospital-based surgery at other specialties (P = 0.001).

Conclusions

Elderly patients with diabetes mellitus or previous hospital-based surgeries at other specialties have a higher rate of positive bacterial culture in the conjunctival sac before cataract surgery. This study would provide a hint for identifying patients at risk for carrying bacterial flora in the conjunctival sac.

Severe Ocular Bacterial Infections: A Retrospective Study Over 13 Years

PURPOSE

To report data of samples collected from January 2000 to August 2013, in the Department of Diagnosis and Laboratory Analysis, Ophthalmic Hospital, Turin, Italy, from different types of ocular infections and their antibiotic susceptibility.

METHODS

Collected samples were cultured using both liquid and solid media. Then bacterial isolates were tested for antibiotic susceptibility using the Kirby-Bauer diffusion method and the National Committee for Clinical Laboratory Standards (NCCLS) serum standards.

RESULTS

Staphylococcus aureus is the most common bacteria isolated in ocular samples.

CONCLUSIONS

In vitro susceptibility tests showed that levofloxacin and moxifloxacin (introduced only in 2010) had the highest efficacy against bacterial isolates.

Nasal and conjunctival screening prior to refractive surgery: an observational and cross-sectional study

OBJECTIVES

To investigate bacterial flora of clinically healthy conjunctiva and nasal cavity among patients prior to refractive surgery, as well as the characteristics of patients with methicillin-resistant Staphylococcus aureus (MRSA) colonisation.

DESIGN

Observational and cross-sectional study.

SETTING

A single-centre study in Japan.

PARTICIPANTS

120 consecutive patients pre-refractive surgery.

PRIMARY AND SECONDARY OUTCOME MEASURES METHODS

Samples were obtained from the right conjunctival sac and the nasal cavity of 120 consecutive patients prior to refractive surgery and were then measured for the levels of the minimum inhibitory concentration (MIC) of antibiotics. Patients were interviewed regarding their occupation, family living situation and any personal history of atopic dermatitis, asthma, smoking or contact lens wear.

RESULTS

Propionibacterium acnes (P. acnes) (32.5%) and Staphylococcus epidermidis (4.2%) were detected from the conjunctival sac. S. epidermidis was the most commonly isolated (68.3%) in the nasal cavity. Of the 30 patients (25.0%) with colonisation by S. aureus, 2 patients, both of whom were healthcare workers with atopic dermatitis, were found to be positive for MRSA in the nasal cavity. A history of contact lens wear, asthma or smoking, as well as patient gender and age, was not associated with MRSA colonisation.

CONCLUSIONS

There were only 2 patients who were colonised with MRSA, both of whom were healthcare workers with atopic dermatitis. P. acnes was predominantly found in the conjunctival sac. Further study is needed to investigate the involvement between nasal and conjunctival flora, and risk factors for infectious complications.

Assessment of risk factors for oxacillin-resistant ocular flora in eyes having cataract surgery

PURPOSE

To assess the risk factors for eyes of cataract surgery patients harboring oxacillin-resistant Staphylococcus species on the ocular surface.

SETTING

Ambulatory surgical center, Saint Louis University, Saint Louis, Missouri, USA.

DESIGN

Prospective in vitro laboratory study of a patient cohort.

METHODS

Conjunctival cultures were obtained on the day of surgery from eyes scheduled for cataract surgery. Patients answered a questionnaire about risk factors that might lead to having oxacillin-resistant Staphylococcus organisms in their eyes. The factors tested were age, sex, race, recent systemic and topical antibiotic usage, recent hospitalization, and exposure to healthcare and institutional settings. Logistic regression analysis was performed.

RESULTS

Of the 183 eyes cultured, 128 (70.0%) tested positive for Staphylococcus organisms, of which 70 (54.7%) were oxacillin-resistant. Only recent antibiotic usage was statistically significantly associated with the presence of oxacillin-resistant organisms (odds ratio, 8.2; 95% confidence interval, 2.2-30.5; P=.002). The other risk factors were not statistically significantly associated: age (P=.06), sex (P=.33), race (P=.34), recent hospitalization (P=.94), and exposure to healthcare and institutional settings (P=.10).

CONCLUSIONS

Although the nonophthalmic literature has reported various risk factors for the harboring of oxacillin-resistant organisms, in the eyes in this study, only antibiotic usage within 30 days preoperatively was significantly associated with the colonization of oxacillin-resistant organisms on the ocular surface. This finding is important to ophthalmic surgeons when considering perioperative antibiotic prophylaxis.

FINANCIAL DISCLOSURE

No author has a financial or proprietary interest in any material or method mentioned.

Incidence of corneal infections after laser in situ keratomileusis and surface ablation when moxifloxacin and tobramycin are used as postoperative treatment

PURPOSE

To assess the incidence, culture results, and visual outcomes of infectious keratitis after laser in situ keratomileusis (LASIK) and surface ablation when topical moxifloxacin was added to postoperative prophylaxis with tobramycin.

SETTING

Clínica Baviera, Instituto Oftalmológico Europeo, Bilbao, Spain.

DESIGN

Retrospective case series review.

METHODS

The medical records of 55 255 patients (108 014 eyes) who had LASIK and surface ablation were reviewed to identify cases of infectious keratitis. The incidence, risk factors, clinical course, days to diagnosis, treatment, and final visual outcomes were recorded. These data were compared with previously published data of 221 437 eyes that received postoperative tobramycin alone.

RESULTS

Post-LASIK infectious keratitis was diagnosed in 10 eyes (9 patients) and post-surface ablation infectious keratitis in 11 eyes (10 patients). The onset of infection was early in 40.00% of cases after LASIK and in 36.36% after surface ablation. Cultures were positive in 2 cases after surface ablation. Immediate flap lifting and irrigation with antibiotics were performed in all eyes after LASIK. The final corrected distance visual acuity was 20/20 or better in 7 cases after LASIK (70.00%) and 7 cases after surface ablation (63.64%) and 20/40 or better in all cases after LASIK or surface ablation.

CONCLUSIONS

The incidence of infectious keratitis decreased from 0.025% to 0.011% (P < .001) per procedure after LASIK and from 0.200% to 0.066% (P < .001) after surface ablation. Infectious keratitis was less frequent after LASIK than after surface ablation. The frequency of infection, mainly early-onset infection, was lower when the postoperative treatment was tobramycin and moxifloxacin rather than tobramycin alone.

FINANCIAL DISCLOSURE

No author has a financial or proprietary interest in any material or method mentioned.

Risk factors for fluoroquinolone resistance in ocular cultures

Purpose

To identify the risk factors associated with fluoroquinolone resistance in patients undergoing cataract surgery.

Methods

A total of 1,125 patients (1,125 eyes) who underwent cataract surgery at Veterans Health Service Medical Center from May 2011 to July 2012 were enrolled in this study. Conjunctival cultures were obtained from the patients on the day of surgery before instillation of any ophthalmic solutions. The medical records of patients with positive coagulase negative staphylococcus (CNS) and Staphylococcus aureus (S. aureus) cultures were reviewed to determine factors associated with fluoroquinolone resistance.

Results

Of 734 CNS and S. aureus cultures, 175 (23.8%) were resistant to ciprofloxacin, levofloxacin, gatifloxacin, or moxifloxacin. Use of fluoroquinolone within 3 months and within 1 year before surgery, topical antibiotic use other than fluoroquinolone, systemic antibiotic use, recent hospitalization, ocular surgery, intravitreal injection and use of eyedrops containing benzalkonium chloride were significantly more frequent in resistant isolates than in susceptible isolates. In multivariable logistic regression analysis, ocular surgery (odds ratio [OR], 8.457), recent hospitalization (OR, 6.646) and use of fluoroquinolone within 3 months before surgery (OR, 4.918) were significant predictors of fluoroquinolone resistance, along with intravitreal injection (OR, 2.976), systemic antibiotic use (OR, 2.665), use of eyedrops containing benzalkonium chloride (OR, 2.323), use of fluoroquinolone within 1 year before surgery (OR, 1.943) and topical antibiotic use other than fluoroquinolone (OR, 1.673).

Conclusions

Recent topical fluoroquinolone use, hospitalization and ocular surgery were significantly associated with fluoroquinolone resistance in CNS and S. aureus isolates from ocular culture.

Needle contamination in the setting of intravitreal injections

BACKGROUND/PURPOSE

To evaluate the risk of intravitreal needle contamination through speaking versus breathing in an office setting.

METHODS

This was a prospective sampling assay. Participants held a sterile 30-gauge half-inch needle 25 cm from their mouth for 30 seconds under 2 conditions: (1) while speaking and (2) while breathing silently. Needles were then cultured and assayed after 6 days of incubation. Absolute colony-forming units were compared between conditions and against control sterile needles and oral swab cultures.

RESULTS

Ten physicians were sampled with 15 samples per physician. Participants grew an average of 0.21 colonies (median = 1 CFU) from their talking samples and 0.07 colonies (median = 1 CFU) from their silent breathing samples. Oral swab plates grew an average of 373.4 colonies. None of the control needle plates grew colony-forming units. A nominal regression analysis showed no significant difference between talking and silent samples (P = 0.457).

CONCLUSION

No significant difference in needle contamination was found between talking and breathing. Compared with oral swab plates, a significant difference exists between the amount of flora colonizing the oropharynx and that which was found on the needle cultures (P < 0.0001). These findings suggest that speaking versus remaining silent makes no difference in regard to needle contamination with oral flora during intravitreal injection.

Resistance of ocular flora to gatifloxacin in patients undergoing intravitreal injections

OBJECTIVE

To compare gatifloxacin resistance in a population of ophthalmology patients who had received intravitreal injections (IVIs) with prophylactic topical gatifloxacin use to resistance in a similar population of patients who had not received IVI.

DESIGN

Nested case-control study.

PARTICIPANTS

Fifty eyes of 50 patients who received prior IVI were enrolled, as were 50 control eyes.

METHODS

Each patient had a conjunctival swab performed on the study eye, which underwent microbial identification and testing for gatifloxacin resistance using the ellipsoid test to determine a minimum inhibitory concentration (MIC) value for each isolate. The primary outcome was susceptibility to gatifloxacin, as measured by the MIC of each isolate.

RESULTS

A total of 111 bacterial isolates were obtained from 60 eyes; the remainder was culture negative. There were no significant differences in bacterial species or culture positivity rate between case and control eyes (50% in cases vs. 66% in controls, p = 0.16). The most common organism was coagulase-negative staphylococcus, comprising 64% of all isolates. Resistance to gatifloxacin was observed in 76% of the bacterial isolates and 38% of patients in the case group, as compared with 3% of bacterial isolates and 4% of patients in the control group, a result that was statistically significant (p = 0.0002 and 0.0008, respectively). The mean gatifloxacin MIC was also significantly higher in the case group.

CONCLUSIONS

Topical gatifloxacin prophylaxis in those who receive IVI is associated with an increased rate of gatifloxacin resistance among conjunctival isolates.

Bacillus Spp. isolated from the conjunctiva and their potential antimicrobial activity against other eye pathogens

BACKGROUND

In this study, we attempted to screen and investigate antibacterial activity of Bacillus species, which were isolated from conjunctiva, against other eyes pathogens.

METHODS

To examine predominant isolates of Bacillus subtilis, B. pumilus, B. cereus and B. mojevensis, isolated from conjunctiva for their antimicrobial activity against indicator microorganisms as Micrococcus luteus, Staphyloccocus aureus, S. epidermidis, S.hominis, S. lugdunensis, S.warneri, S. haemolyticus, B. cereus, Listeria monocytogenes, and Proteus mirabilis. Growth inhibitions of indicator microorganisms were tested using agar diffusion tests by cells and supernatants of five B. mojevensis, one B. subtilis, four B. cereus and five B. pumilus strains which were isolated from conjunctiva.

RESULTS

The Bacillus isolates showed variable ability of inhibition against the tested microorganisms. Two strains of B. pumillus, 1 strain of B. subtilis, 5 strains of B. mojevensis, 1 strain of B. cereus were efficacious against the tested microorganisms. Most resistant microorganism to these bacteria was Proteus mirabilis. Two of Gram positive bacteria, S. lugdenensis (K15-9) and S. aureus (SDA48), were also found as resistant.

CONCLUSIONS

In this study, Bacillus spp isolated from conjunctiva showed antimicrobial activity against Gram-positive bacteria. Human eye-derived microorganisms and their antimicrobial effects might be a useful source of natural products for the future.

Moxifloxacin modifies corneal fibroblast-to-myofibroblast differentiation

BACKGROUND AND PURPOSE

Fibroblast-to-myofibroblast differentiation is associated with scarring, an important issue in corneal surgery. Moxifloxacin (MOX), commonly applied to prevent post-operative infection, would benefit more if it modifies fibroblast-to-myofibroblast differentiation other than antimicrobial activity. Our purpose was to explore whether MOX has anti-fibrotic effect in human corneal fibroblasts (HCFs).

EXPERIMENTAL APPROACH

HCFs were incubated in MOX-containing medium concurrently with TGF-β1 (co-treatment), before (pretreatment) or after (post-treatment) adding TGF-β1. HCF contractility was evaluated with a type I collagen gel contraction assay. Expression of α-smooth muscle actin (α-SMA), Smad2, phospho-Smad2-Ser467, Smad4 and Smad7 was determined by immunoblotting. Formation of α-SMA-positive filaments and distribution of active Smad2 were observed under confocal microscopy. Expression of TGF-β receptor types I (TGFBR1) and II (TGFBR2) was assessed with flow cytometry.

KEY RESULTS

MOX did not affect gel contractility or α-SMA filament formation in HCFs without TGF-β1 stimulation. MOX did, however, retard HCF-containing gel contractility and α-SMA filament formation following TGF-β1 stimulation in the pretreatment and co-treatment groups but not in the post-treatment group. MOX blocked the expression of Smad2, phospho-Smad2-Ser467 and TGFBR1 under TGF-β1 incubation. Additionally, MOX enhanced Smad7 expression in TGF-β1-incubated HCFs, but did not interfere with TGF-β-triggered Smad2 nuclear translocation or Smad4 expression.

CONCLUSIONS AND IMPLICATIONS

MOX inhibited TGF-β-induced fibroblast-to-myofibroblast differentiation via blocking TGFBR1 and enhancing Smad7 expression. MOX should be used before or during surgery to achieve these effects. These results suggest a de novo mechanism by which MOX participates in corneal wound healing.

Ocular flora and their antibiotic resistance patterns in the midwest: a prospective study of patients undergoing cataract surgery

PURPOSE

To determine the spectrum of conjunctival flora and the antibiotic susceptibility profiles of patients undergoing cataract surgery at a Midwestern university.

DESIGN

Prospective in vitro laboratory investigation of a patient cohort.

METHODS

Conjunctival cultures were obtained from patients undergoing cataract surgery at a single ambulatory center on the day of surgery before the instillation of any ophthalmic medications. Isolates and antibiotic susceptibility profiles were identified using standard microbiological techniques.

RESULTS

A total of 183 eyes were cultured, yielding 225 isolates. Twenty-seven eyes (14.8%) showed no growth. Coagulase-negative staphylococci (CNS) were the most commonly isolated organisms (74.8%). Overall susceptibility was highest for gentamicin (94%), which was also true of the CNS isolates (95.0%). A total of 64.5% of CNS isolates were sensitive to ciprofloxacin; 30.1% of CNS isolates were resistant to ≥3 classes of antibiotics; 46.6% of CNS isolates were oxacillin-resistant, and they were more resistant to antibiotics than their oxacillin-sensitive counterparts (P < .001), including fluoroquinolones (P < .001). Among eyes with multiple CNS strains, 41.4% had different antibiotic susceptibility profiles even though they were the same species.

CONCLUSIONS

Our cohort harbored organisms with similar rates of antibiotic resistance as elsewhere in the country, including oxacillin resistance; however, the rate of fluoroquinolone resistance was less than in other reports. A surprisingly large proportion of different CNS strains from the same eye harbored different antibiotic susceptibility profiles. Our in vitro results, along with those of other investigators, should prompt further dialogue regarding antibiotic of choice for perioperative surgical prophylaxis in ophthalmic surgery.

Paediatric bacterial keratitis cases in Shanghai: microbiological profile, antibiotic susceptibility and visual outcomes

PURPOSE

The purpose of this study was to review the microbiological profile, in vitro antibiotic susceptibility and visual outcomes of paediatric microbial keratitis in Shanghai, China over the past 6 years.

METHODS

Medical records of patients aged ≤16 years were reviewed, who were diagnosed as having bacterial keratitis between 1 January 2005 and 31 December 2010. Bacterial culture results and in vitro antibiotic susceptibility were analysed. A logistic regression analysis was conducted to evaluate the relationship between visual impairment and possible risk factors.

RESULTS

Eighty consecutive cases of paediatric bacterial keratitis cases were included, among which 59 were identified as having positive culture. Staphylococcus epidermidis was the most commonly isolated organism (n=23; 39.0%), followed by Streptococcus pneumoniae (n=11; 18.6%) and Pseudomonas aeruginosa (n=6; 10.2%). Antibiotic sensitivities revealed that tested bacteria had low resistance rates to fluoroquinolones and aminoglycosides (8.3-18.4% and 12.5-24.4%, respectively). Multivariate logistic regression analysis proved that visual impairment was significantly associated with Gram-negative bacterial infection (odds ratio (OR)=7.626; P=0.043) and an increasing number of resistant antibiotics (OR=0.385; P=0.040).

CONCLUSIONS

S. epidermidis was the most common isolated organism in Shanghai paediatric keratitis. The fluoroquinolones and aminoglycosides remained good choices for treating these patients. Gram-negative bacterial infection and an increasing number of resistant antibiotics were associated with worse visual prognoses in paediatric keratitis.

Association of conjunctival bacterial infection and female sex in cicatricial trachoma

PURPOSE

Conjunctival infection with non-chlamydial bacteria may play an important role in the progression of trachoma, especially with regard to the development of corneal opacity and blindness. To further characterize the microbiological profile of bacterial conjunctival infections in cicatricial trachoma, a conjunctival swabbing of adults in rural Ethiopia was performed.

METHODS

In a cross-sectional study conducted in nine Ethiopian villages with hyperendemic trachoma, persons 40 years of age or older with signs or symptoms consistent with trichiasis were recruited and conjunctival swabbing for bacterial pathogens was performed.

RESULTS

Conjunctival examination and swabbing on 112 females and 36 males were performed. Of the 148 study participants, 101 (68.2%) were confirmed to have trichiasis, and 118 (80%) had conjunctival swabs positive for bacteria. In multivariate analyses, growth of pathogenic conjunctival bacteria was independently associated with trichiasis (odds ratio [OR] 6.93; 95% confidence interval [CI] 2.71-17.7) and female sex (OR 5.90; 95% CI 2.09-16.7). Females were more likely to have swabs positive for Streptococcus pneumoniae or Haemophilus influenzae than were males (OR 9.09; 95% CI 1.17-70.8).

CONCLUSIONS

In a region of Ethiopia with endemic trachoma, conjunctival bacterial growth was more common in females than that in males. S. pneumoniae and H. influenzae, both of which frequently colonize the nasopharynx of children, were more common in females, suggesting that the preponderance of infection in females may be attributable to close contact with children. This finding is consistent with the theory that childcare activities may preferentially expose females to ocular chlamydial infection. (ClinicalTrials.gov number, NCT00221364.).

Conjunctival microbial florae in patients with seriously sulfur mustard induced eye injuries

INTRODUCTION

Ocular surface disorders and infections in sulfur mustard (SM) exposed patients are of particular clinical importance. The aim of the present study is to detect the conjunctival bacterial florae in patients with seriously SM induced eye injuries.

MATERIALS AND METHODS

Conjunctival bacterial florae of 143 seriously eye injured subjects as the study group was detected. The results were compared with 26 normal participants. Both groups were matched in age and sex. The samples were taken by sterile swab from interior fornixes of conjunctiva in both groups and were transported to microbiology laboratory by Stuart's Transport Medium. All samples were inoculated onto Blood agar, Mac Conkey agar and Chocolate agar and isolated microorganisms were identified by biochemical tests. The data were analyzed by SPSS and Man Whitney tests.

RESULTS

Nineteen cases (13.39%) and none of the controls (0%) had positive culture results (p = .043). Isolated microorganisms from patients included coagulase-negative staphylococci 10 cases (52.6%), Staphylococcus aureus 5 cases (26.3%), non enterobacteriaceae gram negative bacilli 2 cases (10.5%), Penicillium spp. 2 cases (10.5%), Citrobacter sp. 1 case (5.2%), non-spore forming Gram positive bacillus 1 case (5.2%) and α hemolytic streptococcus 1 case (5.2%). Two patients had mixed microorganisms and other patients had just one microorganism. Most of the S. aureus isolates were sensitive to usual antibiotics.

CONCLUSIONS

The results of this study showed that the prevalence rate of conjunctival bacterial isolates in patients with seriously SM induced ocular injuries are higher and potentially more dangerous than normal controls.

Changes in antibiotic resistance patterns of conjunctival flora due to repeated use of topical antibiotics after intravitreal injection

OBJECTIVE

To determine the effect of repeated intermittent use of topical antibiotics after intravitreal injections on conjunctival bacterial flora and antibiotic resistance.

DESIGN

Cross-sectional case-control study.

PARTICIPANTS AND CONTROLS

A total of 80 eyes of 40 patients were enrolled (40 study eyes, 40 control eyes). Patients were enrolled with unilateral exudative age-related macular degeneration who had received at least 3 prior intravitreal injections with use of postinjection topical antibiotics. Patients had received an average of 7 (range, 3-13) intravitreal injections before enrollment.

METHODS

At the time of enrollment, the inferior fornix of the treated eye was swept with a culture swab before use of povidone iodine; the inferior fornix of the fellow eye was also cultured and served as a control. The culture and sensitivity data from the study and control eyes were analyzed.

MAIN OUTCOME MEASURES

The rate of antibiotic resistance among the conjunctival bacterial flora of the study eyes and control eyes.

RESULTS

A total of 80 eyes of 40 patients were enrolled in the study; 29 patients used trimethoprim/polymyxin B drops, and 11 patients used fluoroquinolone drops after each injection. A total of 58 bacterial colonies were isolated from 50 eyes. There were no significant differences in bacterial species or culture positivity rates between study and control eyes. Coagulase-negative staphylococcus accounted for 41 of the 58 bacterial colonies (71%). There was a 63.6% resistance rate to fluoroquinolones among study eyes compared with 32.1% among control eyes (P < 0.05). In the subset of 11 study eyes using fluoroquinolone drops for 4 days after injection, there was an 87.5% resistance rate compared with 25.0% in matched control eyes (P = 0.04). There was no significant difference in trimethoprim resistance rates between study and control eyes: Four of 14 study eyes (28.6%) showed resistance compared with 5 of 18 control eyes (27.7%) (P = 1.0).

CONCLUSIONS

Use of fluoroquinolone drops after intravitreal injection leads to increased rates of resistance among conjunctival flora. Repeated use of topical fluoroquinolones after intravitreal injections may have a detrimental effect on eye health by breeding resistance in the bacterial flora.

Microbial keratitis after corneal laser refractive surgery

Corneal laser refractive surgery is increasingly being performed on patients with the aim of improving unaided vision. Most candidates for surgery have excellent spectacle- or contact lens-corrected vision. Although microbial keratitis following refractive surgery is a rare complication, and usually has a good visual outcome, it can be sight-threatening. The spectrum of pathogens differs to other causes of microbial keratitis, such as contact lens-associated keratitis, and a different management approach is required. Postoperatively, patients are prescribed topical steroids and broad-spectrum topical antibiotics, typically fluoroquinolones. These do not cover unusual organisms, such as fungi, Nocardia, Acanthamoeba and some atypical mycobacteria. In post-laser-assisted in situ keratomileusis microbial keratitis, the lamellar flap should be lifted to acquire samples for specific microbiological examination, including these atypical organisms. Confocal microscopy is a noninvasive test that provides morphological information, and is operator dependent, but may assist in the rapid diagnosis of fungal, Acanthamoeba or Norcardia keratitis. PCR is not in widespread use, but has high sensitivity and specificity, and may facilitate early diagnosis and specific treatment of the causative organism, which is critical in obtaining the best clinical outcome.

Infectious keratitis in 18,651 laser surface ablation procedures

PURPOSE

To evaluate the incidence, culture results, risk factors, treatment strategies, and visual outcomes of infectious keratitis after surface ablation.

SETTING

Multicenter study in Spain.

DESIGN

Case series.

METHODS

The medical records of patients who had surface ablation between January 2003 and December 2009 were reviewed to identify cases of infectious keratitis. The incidence, risk factors, clinical course, days to diagnosis, medical and surgical treatment, and visual outcome were recorded. Main outcome measures were incidence of infectious keratitis after surface ablation, culture results, response to treatment, and visual outcomes.

RESULTS

The study reviewed the records of 9794 patients (18,651 eyes). Infectious keratitis after surface ablation was diagnosed in 39 eyes of 38 patients. The onset of infection was early (within 7 days after surgery) in 28 cases (71.79%). Cultures were positive in 13 of 27 cases in which samples were taken. The most frequently isolated microorganism was Staphylococcus species (9 cases). The final corrected distance visual acuity (CDVA) was 20/20 or better in 23 cases (58.97%), 20/40 or better in 36 cases (92.30%), and worse than 20/40 in 3 cases (7.69%).

CONCLUSIONS

The incidence of infectious keratitis after surface ablation was 0.20%. Infectious keratitis is a potentially vision-threatening complication. Prompt and aggressive management with an intensive regimen of fortified antibiotic agents is strongly recommended. Proper management can preserve useful vision in most cases.

FINANCIAL DISCLOSURE

No author has a financial or proprietary interest in any material or method mentioned.

Contamination of contact lens storage cases of asymptomatic refractive surgery candidates

PURPOSE

To examine the rates of contamination of contact lens storage cases of refractive surgery candidates and compare the growth yields of the traditional method of culturing and a broth-based method.

METHODS

Thirty contact lens storage cases of 16 asymptomatic refractive surgery candidates were studied. Samples from the lens storage case fluid were inoculated into Bactec Peds Plus F broth (Becton Dickinson) and also directly onto blood agar, chocolate agar, and Sabouraud dextrose agar ("traditional method"). Another sample was processed for amoebal contamination. The rate of contamination of cases and the types of pathogens were evaluated for the broth-based and traditional culturing methods. Correlation between right and left storage cases of the same patient was defined as contamination of the two compartments with the same pathogen or pathogens. To avoid statistical bias, only one compartment was included in the study for these patients.

RESULTS

Four storage cases were omitted due to growth correlation between right and left storage cases. Of the remaining 26 storage cases, 16 (61.5%) were found to be contaminated using the broth-based method and 10 (38.5%) using the traditional method (P=.011). High contamination rates were observed regardless of the type of disinfecting solution or type of contact lens used.

CONCLUSIONS

The broth-based method had significantly greater culture yield than the traditional method. The high rates of contamination of contact lens storage cases of refractive surgery patients may put this cohort at greater risk than non-contact lens wearing candidates for developing postoperative infections.

Antibiotic resistance of conjunctiva and nasopharynx evaluation study: a prospective study of patients undergoing intravitreal injections

PURPOSE

To determine the baseline antibiotic susceptibility patterns of conjunctival and nasopharyngeal flora isolated from patients undergoing intravitreal (IVT) injections for choroidal neovascularization (CNV).

DESIGN

Prospective, observational study.

PARTICIPANTS

Forty-eight eyes of 24 patients undergoing unilateral IVT injections for CNV.

METHODS

Bilateral conjunctival and unilateral nasopharyngeal cultures on the treatment side were taken before application of any topical medications.

MAIN OUTCOME MEASURES

Bacterial isolates were identified and tested for antibiotic susceptibility to 16 different antibiotics using the Kirby-Bauer disc diffusion technique.

RESULTS

A total of 57 bacterial isolates were obtained from the conjunctiva of 48 eyes. Coagulase-negative staphylococci (CNS) accounted for 37 of the 57 isolates (65%). The most common CNS organisms were Staphylococcus epidermidis and Staphylococcus lugdunensis accounting for 73% and 11% of CNS isolates, respectively. More than half of S. epidermidis isolates demonstrated some level of resistance to ofloxacin and levofloxacin, and 33% and 37% of isolates showed some level of resistance against gatifloxacin and moxifloxacin, respectively. Some 60% and 30% of CNS isolates were resistant to ≥ 3 and ≥ 5 antibiotics, respectively. Among the 24 nasopharyngeal cultures, 8 (33%) grew Staphylococcus aureus, and 1 of the 8 isolates (13%) was resistant to all penicillin, cephalosporin, macrolide, and fluoroquinolone antibiotics tested.

CONCLUSIONS

Our results demonstrate subtantial levels of resistance to third- and fourth-generation fluoroquinolones and multiresistance among ocular CNS isolated from patients undergoing IVT injections for CNV.