Bacterial keratitis in a tertiary eye centre in Iran: a retrospective study

Microbiological Profile of Ocular Infection: A Large Retrospective Study

BACKGROUND

We aimed to elucidate the pathogenic bacterial and fungal profiles of specimens obtained from suspected ocular infections at Farabi Eye Tertiary Referral Hospital, Tehran, Iran.

METHODS

In this cross-sectional study, we collected data from ocular specimens taken during the seven-year period of 2011 to 2018, and the results were then retrospectively analyzed. Samples had been obtained from patients who were investigated for ocular infections.

RESULTS

Overall, 16,656 ocular samples were evaluated. The mean patient age was 48.31 ± 26.62 years. Most patients were men (60.33%), and men in the 7th decade of life were the largest represented group. The seasonal distributions of specimen collection sites followed the overall distribution of collection sites by year. Specimens obtained from the cornea were the most common (49.24%), also representing the largest number of specimens in all seasons. The most commonly isolated fungal microorganisms were Fusarium spp., followed by Aspergillus spp. and Candida albicans. Of the 6,556 specimens with positive bacterial cultures, 59% produced gram-positive bacteria, while the remainder produced gram-negative pathogens. The most commonly isolated bacteria were Pseudomonas aeruginosa (17.77%), Staphylococcus epidermidis (13.80%), Streptococcus pneumoniae (13.27%), S. viridans (12.23%), and S. aureus (11.18%).

CONCLUSION

Most submitted specimens were obtained from the cornea. The most commonly isolated fungal microorganisms were Fusarium spp., followed by Aspergillus spp. and C. albicans. The most commonly isolated bacteria were P. aeruginosa, followed by S. epidermidis and S. pneumoniae.

Besifloxacin-loaded ocular nanoemulsions: design, formulation and efficacy evaluation

The purpose of this study was to develop and evaluate nanoemulsions (NEs) containing besifloxacin for ocular drug delivery. Pseudo ternary phase diagrams were constructed using Triacetin (oil), Cremophor® RH 40 (surfactant), and Transcutol®P (co-surfactant) to identify NE regions. Six formulations were developed by low-energy emulsification method and then evaluated for size, refractive index, pH, osmolality, viscosity, and drug release. After accelerated physical stability and bovine conrneal permeation studies, NE2 was chosen as optimized formulation forantimicrobial efficacy, and hen's egg test-chorioallantoic membrane (HET-CAM) tests. The particle size of optimum NE was 14 nm with a narrow size distribution. Moreover, other physicochemical characterizations were in the acceptable range for ocular administration. Besifloxacin-loaded NEs demonstrated sustained release pattern and 1.7-fold higher permeation compared with the control suspension in the ex vivo transcorneal permeation study. HET-CAM test indicated no irritation, and HL% revealed no damage to the tissue, so the optimum NE is well tolerated by the eye. In vitro antimicrobial evaluation, showed comparative efficacy of lower drug-loaded NE (0.2%) versus 0.6% besifloxacin suspension (equal concentration to commercial besifloxacin eye drop). In conclusion, besifloxacin-loaded NEs could be considered as a suitable alternative to the marketed suspension for treating bacterial eyeinfections.

Is Penicillin-Nonsusceptible Streptococcus pneumoniae a Significant Challenge to Healthcare System? A Systematic Review and Meta-Analysis

BACKGROUND

In recent years, antibiotic-resistant pathogens including penicillin-nonsusceptible Streptococcus pneumoniae (PNSP) have posed serious threats against human health. The aim of this meta-analysis was to investigate the prevalence of Streptococcus pneumoniae drug resistance particularly the incidence of PNSP strains in Iran.

METHODS

A systematic search was done in national and international electronic databases using Persian and English keywords. Up until May 20, 2020, a total of 58 publications were detected as eligible articles based on the inclusion and exclusion criteria, and then the selected studies were enrolled for data extraction and meta-analysis according to the PRISMA guidelines.

RESULTS

A high rate of PNSP (46.9%) and multidrug-resistant (MDR) S. pneumoniae (45.3%) in our isolates were evident. Furthermore, total frequency resistance to other drugs in S. pneumoniae was as follows: erythromycin 41.1%, azithromycin 53.2%, tetracycline 39.9%, levofloxacin 1.7%, rifampin 1.2%, clindamycin 31.7%, vancomycin 1.7%, trimethoprim/sulfamethoxazole 63.9%, chloramphenicol 20%, ceftriaxone 10.9%, amoxicillin 30.5%, ciprofloxacin 8.3%, imipenem 6.1%, linezolid 0%, and cefotaxime 8.3%.

CONCLUSION

Although the overall prevalence of cephalosporin- and carbapenem-resistant Streptococcus pneumoniae was low, penicillin-resistant strains, especially PNSP, could become a significant challenge to the healthcare system in Iran. Hence, the prescription of penicillin as the first-choice antibiotic in the treatment of S. pneumoniae infections should be avoided.

Infectious keratitis: trends in microbiological and antibiotic sensitivity patterns

OBJECTIVES

To report the spectrum and trends of isolated microorganisms and their antibiotic susceptibility profile in patients with infectious keratitis in a 6-year period at a referral centre in Tehran.

METHODS

The microbiology records of all corneal scrapings with a diagnosis of infectious keratitis were reviewed.

RESULTS

A total of 6282 corneal scrapings were performed during the study period, of which 2479 (39.5%) samples were culture positive. Pseudomonas aeruginosa was found to be the most common causative agent in patients with keratitis, although Streptococcus pneumonia was the most prevalently isolated microorganism in patients older than 50 years. Fusarium sp. was the most common responsible pathogen in patients with fungal keratitis. The prevalence of bacterial keratitis due to gram positive microorganisms increased over time, however the number of Pseudomonas keratitis decreased in the second half of the study. Gram negative organisms showed a good sensitivity to levofloxacin, however, 34.1% of S. aureus isolates and 29.7% of coagulase negative staphylococci were resistant to this antibiotic. The odds of ciprofloxacin and levofloxacin resistance increased 1.25 and 1.15 for each 1-year increase in culture date, respectively (P < 0.001, P = 0.004).

CONCLUSIONS

We documented an increasing trend in the percentage of gram positive bacteria. Levofloxacin monotherapy might still be a good option in patients with gram negative bacterial keratitis, however owing to increasing resistance of staphylococci to fluoroquinolones, a regimen consisting of a combination of fortified antibiotics may be more effective in staphylococcal keratitis.

Efficacy of Honey-based Ophthalmic Formulation in Patients with Corneal Ulcer: A Randomized Clinical Trial

AIM

The aim of this study was to evaluate the efficacy of honey-based ophthalmic drop in patients with foreign body induced corneal ulcer.

BACKGROUND

Honey is traditionally used for skin, mucosal and corneal ulcers. Its use is well studied in human skin and mucosal ulcers and animal model of corneal ulcer with promising effects.

METHODS

In this randomized clinical trial, 50 patients with foreign body induced corneal ulcer were allocated to receive 70% sterile honey-based ophthalmic formulation or 0.3% ophthalmic ciprofloxacin, as the standard treatment every 6 hours. All the patients were examined for the size of corneal epithelial defect, corneal infiltration and depth and followed on a daily basis until complete healing. Duration for complete healing was considered as the outcome measure. Smear, culture, antibiogram and minimum inhibition concentration (MIC) tests were performed for honey and ciprofloxacin in all patients.

RESULTS

The average durations of complete healing of corneal epithelial defect in the honey and ciprofloxacin groups were 3.88 ± 3.44 vs. 6.32 ± 3.69days, respectively (p=0.020). No significant difference was observed between two groups regarding an average duration of healing of corneal infiltration (8.12 ±1.94 days vs. 8.64±2.15 days, p=0.375). MIC of honey for pseudomonas aeruginosa was 60%w/w, for E.Coli 40% w/w, and for staphylococcus aureus 30% w/w.

CONCLUSION

Honey based ophthalmic drop can acceleratethe corneal epithelial defect healing in patients with foreign body induced corneal ulcer, compared to ophthalmic ciprofloxacin as a standard treatment. The study was registered in Iranian registry of clinical trial center (IRCT) with registration number IRCT2015020120892N1.

The Spectrum of Microbial Keratitis: An Updated Review

Background:

In microbial keratitis, infection of the cornea can threaten vision through permanent corneal scarring and even perforation resulting in the loss of the eye. A literature review was conducted by Karsten, Watson and Foster (2012) to determine the spectrum of microbial keratitis. Since this publication, there have been over 2600 articles published investigating the causative pathogens of microbial keratitis.

Objective:

To determine the current spectrum of possible pathogens implicated in microbial keratitis relative to the 2012 study.

Methods:

An exhaustive literature review was conducted of all the peer-reviewed articles reporting on microbial pathogens implicated in keratitis. Databases including MEDLINE, EMBASE, Scopus and Web of Science were searched utilising their entire year limits (1950-2019).

Results:

Six-hundred and eighty-eight species representing 271 genera from 145 families were implicated in microbial keratitis. Fungal pathogens, though less frequent than bacteria, demonstrated the greatest diversity with 393 species from 169 genera that were found to cause microbial keratitis. There were 254 species of bacteria from 82 genera, 27 species of amoeba from 11 genera, and 14 species of virus from 9 genera, which were also identified as pathogens of microbial keratitis.

Conclusion:

The spectrum of pathogens implicated in microbial keratitis is extremely diverse. Bacteria were most commonly encountered and in comparison, to the review published in 2012, further 456 pathogens have been identified as causative pathogens of microbial keratitis. Therefore, the current review provides an important update on the potential spectrum of microbes, to assist clinicians in the diagnosis and treatment of microbial keratitis.

Bacterial etiology and antimicrobial resistance trends in ocular infections: A 30-year study, Turin area, Italy

PURPOSE

Bacterial ocular infections can result in loss of all or part of the ocular structures, contributing to a high disability charge. Local surveillance of etiology and susceptibility patterns is crucial for an appropriate empiric management of ocular infections. The aim of this study was to analyze of bacterial spectrum in culture-proven ocular infections and trends of antimicrobial susceptibility patterns.

METHODS

A monocentric retrospective study was performed including ocular infection cases diagnosed at the Microbiology Unit of Turin Ophthalmic Hospital between 1988 and 2017. Spectrum of pathogens that caused bacterial culture-proven ocular infections and trends of antimicrobial susceptibility patterns were analyzed.

RESULTS

A total of 15,517 culture-positive isolates were identified as causative agents of ocular infections. Gram-positive bacteria were deemed to cause infection in 73.5% of cases. Staphylococcus spp. and Pseudomonas spp., coagulase-negative staphylococci, Staphylococcus aureus were the leading causative pathogens of keratitis, endophthalmitis, and conjunctivitis, respectively. Statistically significant changes in temporal trends were observed for all analyzed microorganism groups except for Enterobacteriaceae group. Overall, fluoroquinolones and chloramphenicol demonstrated to be the most effective antimicrobials in vitro toward bacterial ocular infections, followed by tetracycline, ampicillin, and aminoglycosides. Enterobacteriaceae isolates showed higher multi-drug resistance rate, followed by coagulase-negative staphylococci. Analysis of resistance rates over time highlighted increasing resistance trend for aminoglycosides among Gram-negative and for both aminoglycosides and fluoroquinolones among Gram-positive pathogens, especially for S. aureus.

CONCLUSION

This study provided a 30-year assessment of bacterial ocular infections in an urban area of Italy, giving support to epidemiological consciousness and guiding empiric antimicrobial therapy.

Microbiological Profile of Corneal Ulcers at a Tertiary Referral Center

The aim of this study was to describe patient demographics, microbiological profile, and antibiotic susceptibility of corneal ulcer at a tertiary referral center to improve and optimize diagnosis and treatment of this potentially blinding entity and to reduce antibiotic misuse. Detailed external and slit-lamp bio-microscopic examination of 123 consecutive patients with suspected corneal ulcer was performed at an ophthalmology clinic. Corneal scraping was carried out under slit-lamp bio-microscopy. The obtained material was inoculated on culture media and smeared on a slide for Gram's staining for morphological identification of bacteria and fungus. For samples that developed colony in culture media, antibiotic susceptibility testing was performed. In a significant percentage of patients (72%) neither bacterial agents nor fungi were the cause of corneal ulcer. Of the 34 culture-proven corneal ulcers, in 79% of the cases, bacteria were detected while in 21% of cases, fungi were found. Of the 27 bacterial corneal ulcers, the majority were (67%) caused by Gram-positive bacteria, of which 50% were Streptococcus pneumoniae, and in the Gram-negative bacterial corneal ulcers, most of the cases (44%) were caused by Pseudomonas aeruginosa. In the antibiotic susceptibility report, Streptococcus pneumoniae, Staphylococcus aureus, Pseudomonas aeruginosa, and Escherichia coli were resistant to Cotrimoxazole (TS), Streptococcus pneumoniae to Erythromycin (E), Staphylococcus aureus to Peniciline (PG), Pseudomonas aeruginosa to Ceftriaxone (CRO) and Nitrofurantoin (NI), and finally, Escherichia coli to Gentamicin (GM). In conclusion, in a significant number of the patients neither bacterial agents nor fungi were offending microorganisms and bacteria were the most common agent of microbiological corneal ulcer, found in 79% of culture-proven corneal ulcers, followed by fungus, found in 21% of culture-proven corneal ulcers.

Bacterial profile of ocular infections: a systematic review

BACKGROUND

Bacteria are the major contributor of ocular infections worldwide. Ocular infections, if left untreated, can damage the structures of the eye with possible blindness and visual impairments. This work was aimed to review the bacterial profile of ocular infections.

METHODS

Literature search was made in different electronic databases; the review was systematically made to get concrete findings.

RESULTS

As far as this review, Staphylococcus aureus, Coagulase negative Staphylococci, Streptococcus pneumoniae and Pseudomonas aeruginosa are the leading isolates in ocular infections. Frequent pathogens of the respective clinical diagnose include Staphylococci, Streptococcus pyogenes and Pseudomonas aeruginosa in blepharitis; Staphylococci, Streptococus pneumoniae, Pseudomonas aeruginosa, Klebsiella pneumoniae and Escherichia coli in Conjunctivitis; Staphylococci, P. aeruginosa and E. coli in dacryocystitis; Coagulase negative Staphylococci, Pseudomonas aeruginosa and Staphylococcus aureus in keratitis; Streptococcus viridians, Streptococcus pneumoniae and Coagulase negative Staphylococci in endophthalmitis diagnoses. Endogenous endophthalmitis is associated with Klebsiella pneumoniae whereas Coagulase negative Staphylococci and Bacillus spp. are common causes of post-operative and post-traumatic endophthalmitis. However, the predominant pathogens may not be exactly same in all areas of the world, in the United States for instance, Staphylococcus aureus, Streptococcus pneumoniae and Haemophilus influenzae are the major causes of conjunctivitis.

CONCLUSION

Gram positive bacteria are the major contributor of bacterial ocular infections. The distribution and proportion of bacterial isolates among clinical diagnoses varied but without exclusive anatomical restriction. To mitigate the burden of bacterial ocular infections, physicians should regard on risk reduction and comply with etiologic approach of diagnosis.

Ocular bacterial infections at Quiha Ophthalmic Hospital, Northern Ethiopia: an evaluation according to the risk factors and the antimicrobial susceptibility of bacterial isolates

BACKGROUND

External and intraocular infections can lead to visual impairments, which is a major public health problem. Bacteria are the most frequent pathogens affecting ocular structures; the increasing rate of antimicrobial drug resistance is a worldwide concern. The aim of this study was to determine the occurrence of bacteria in ocular infections, their antimicrobial susceptibility patterns, and risk factors in bacterial ocular infection.

METHODS

A hospital based cross-sectional study was conducted from September 2015 to December 2015 at Quiha Ophthalmic Hospital, Tigray, northern Ethiopia. Ocular specimens from blepharitis, blepharoconjunctivitis, conjunctivitis, keratitis, endophthalmitis, periorbital cellulitis and dacrocystitis were collected from 270 individuals with suspected ocular infection. Data on sociodemographic and risk factors were also collected using a structured questionnaire. Data analysis was performed using SPSS version 21 and 0.05 with a corresponding 95% confidence interval (CI) was considered statistically significant.

RESULTS

Among 270 study subjects, 180 (66.7%) were culture positive for different bacterial isolates. The predominant bacterial isolates were Staphylococcus aureus (40, 22.2%), coagulase negative staphylococci (31, 17.2%) and Pseudomonas aeruginosa (21, 11.7%). Ocular surface disease, ocular trauma, hospitalization and cosmetic application practices were significantly associated with the occurrence of bacterial infection. Concerning antimicrobial susceptibility, most isolates were susceptible to amikacin (137, 93.2%), gentamicin (131, 89.1%) and ciprofloxacin (141, 89.2%). Overall, 40 (22.5%), 34 (19.1%) and 62 (34.8%) isolates were resistant to one, two, and three or more antimicrobials, respectively.

CONCLUSION

Bacteria were isolated from the majority of the study subjects. More than half of the bacterial isolates were resistant at least to one drug and a significant rate of multidrug resistance was detected. Therefore, identification of the etiologic agent and antimicrobial susceptibility testing should be practiced to select the appropriate antimicrobial agent to treat eye infections and prevent the emergence of drug resistant bacteria.