Source of the conjunctival bacterial flora at birth and implications for ophthalmia neonatorum prophylaxis

Targeting the Gut-Eye Axis: An Emerging Strategy to Face Ocular Diseases

The human microbiota refers to a large variety of microorganisms (bacteria, viruses, and fungi) that live in different human body sites, including the gut, oral cavity, skin, and eyes. In particular, the presence of an ocular surface microbiota with a crucial role in maintaining ocular surface homeostasis by preventing colonization from pathogen species has been recently demonstrated. Moreover, recent studies underline a potential association between gut microbiota (GM) and ocular health. In this respect, some evidence supports the existence of a gut-eye axis involved in the pathogenesis of several ocular diseases, including age-related macular degeneration, uveitis, diabetic retinopathy, dry eye, and glaucoma. Therefore, understanding the link between the GM and these ocular disorders might be useful for the development of new therapeutic approaches, such as probiotics, prebiotics, symbiotics, or faecal microbiota transplantation through which the GM could be modulated, thus allowing better management of these diseases.

Ocular surface microbiota: Ophthalmic infectious disease and probiotics

Recently, increasing studies have emphasized the importance of commensal bacteria in humans, including microbiota in the oral cavity, gut, vagina, or skin. Ocular surface microbiota (OSM) is gaining great importance as new methodologies for bacteria DNA sequencing have been published. This review outlines the current understanding and investigation of OSM and introduces the new concept of the gut–eye axis. Moreover, we have collected current studies that focus on the relationship between ophthalmic infectious disease and alterations in the OSM or human gut microbiota. Finally, we discuss the current application of probiotics in ophthalmic infectious disease, its limitations to date, and futural directions.

Characterization and Comparison of Ocular Surface Microbiome in Newborns

The ocular microbiome is of fundamental importance for immune eye homeostasis, and its alteration would lead to an impairment of ocular functionality. Little evidence is reported on the composition of the ocular microbiota of term infants and on the impact of antibiotic prophylaxis. Methods: A total of 20 conjunctival swabs were collected from newborns at birth and after antibiotic treatment. Samples were subjected to 16S rRNA sequencing via system MiSeq Illumina. The data were processed with the MicrobAT software and statistical analysis were performed using two-way ANOVA. Results: Antibiotic prophylaxis with gentamicin altered the composition of the microbiota. In detail, a 1.5- and 2.01-fold reduction was recorded for Cutibacterium acnes (C. acnes) and Massilia timonae (M. timonae), respectively, whereas an increase in Staphylococcus spp. of 6.5 times occurred after antibiotic exposure. Conclusions: Antibiotic prophylaxis altered the ocular microbiota whose understanding could avoid adverse effects on eye health.

Anatomic Characterization of the Ocular Surface Microbiome in Children

The microbiome is important in the evolution of the immune system in children; however, information is lacking regarding the composition of the pediatric ocular microbiome and its surrounding structures. A prospective, cross-sectional study of the ocular microbiome was conducted in children <18 years old. Samples from the inferior conjunctival fornix of both eyes, eyelid margin, and periocular skin underwent DNA amplification and 16S sequencing using Illumina MiSeq 250. The microbiome was analyzed using Qiime. Statistical analysis was performed using a two-sided Student’s t-test, diversity indices, and principal coordinate analysis. A total of 15 children were enrolled. The ocular surface microbiome was predominantly composed of Proteobacteria, whereas Bacteroidetes dominated the eyelid margin, and Firmicutes dominated the periocular skin. Despite these variations, no statistically significant compositional differences were found with Bray-Curtis analysis. The conjunctiva had the lowest Shannon diversity index with a value of 2.3, which was significantly lower than those of the eyelid margin (3.4, p = 0.01) and the periocular skin (3.5, p = 0.001). However, the evenness of the species using Faith’s phylogenetic diversity index was similar at all sites. Overall, the ocular surface microbiome is dominated by Proteobacteria in children. The niche is similar to the surrounding structures in terms of composition, but has a lower number and relative abundance of species.

The newborn conjunctival flora at the post delivery 24 hours

Purpose

The aim of this study was to investigate the aerobic conjunctival flora of neonates and the effects of delivery type on conjunctival flora development in neonates who were born with normal spontaneous vaginal delivery (SVD) or elective caesarean section (C/S) and who were not given prophylactic antibiotic eye drops after birth.

Methods

This cross-sectional study included 95 healthy newborns. One day after the delivery, conjunctival samples were taken from newborns who were born with normal SVD or elective C/S, and not given prophylactic antibiotic eye drops after birth. Newborns with conjunctival hyperemia and discharge were excluded from study. Samples were plated in blood agar, EMB, and chocolate agar. These cultures were incubated at 37 °C for 24-48 h. Antibiotic sensitivity was evaluated using Kirby-Bauer disc diffusion method.

Results

Staphylococcus aureus (S.aureus) growth was observed in 7 (70%) and coagulase negative staphylococcus (CNS) growth in 2 (20%) out of 10 eyes with bacterial growth in 9 culture positive newborns born with C/S. Two S.aureus strains were resistant to methicillin. On the other hand, CNS growth was observed in the conjunctival cultures of 17 out of 19 eyes with bacterial growth in 16 culture positive newborns born with SVD. In 2 eyes with CNS growth, there was also S.aureus growth. The positive cultures for S.aureus were significantly higher in the conjunctival cultures of neonates born with C/S compared to neonates born with SVD, where CNS growth was significantly lower (P = 0.002). All isolates were susceptible to vancomycin, teicoplanin, and gatifloxacin. Two isolates were resistant to methicillin.

Conclusions

In deliveries with C/S, the newborn does not contact the vagina. This may result in changes of bacterial characteristic of the flora. Culture positivity for S.aureus was higher in C/S compared to SVD, which may be important in case neonatal conjunctivitis develops.

Effect of clinical parameters on the ocular surface microbiome in children and adults

Purpose

To perform a pilot study to characterize the effect of clinical parameters on the ocular surface microbiome (OSM) in children and adults using 16s ribosomal RNA sequencing.

Methods

Prospective, cross-sectional study using 16s sequencing to evaluate the OSM. Comparisons were made in bacterial composition by 1) age, 2) gender, 3) sampling location of the ocular and periocular surfaces, and 4) topical drop use. 16s sequencing was performed using Illumina MiSeq 250 and analyzed using Qiime.

Results

Thirty patients (15 children [mean 3.7 years], 15 adults [mean 60.4 years]) were sampled. Both principal coordinate analysis and unifrac distance analysis showed significant differences in the composition between the pediatric and adult OSMs (both p=0.001). The eyelid margin microbiota did not show any distinct clustering compared to conjunctiva within the pediatric samples but tended to show a distinction between anatomic sites in adult samples. No differences in OSM were noted by topical drop use.

Conclusion

16s sequencing is a useful tool in evaluating the OSM in patients of all ages, showing a distinct difference between pediatric and adult microbiomes.

The influence of maternal vaginal flora on the intestinal colonization in newborns and 3-month-old infants

AIM

The role of maternal vaginal bacteria on the colonization of neonatal gut is still a matter of discussion. Our aim was to estimate the role of maternal vaginal flora on the development of intestinal flora in neonates and 3-month-old infants.

METHODS

Seventy-nine maternal-neonatal pairs were included in the study. Vaginal swabs were taken before the rupture of membranes after admission to the delivery ward. First neonatal stool (meconium) and stool at 3-month-old infants were collected and cultured. All samples were subjected to microbiological analysis for Streptococcus, Staphylococcus, Bifidobacterium, Clostridium (including C. difficile), Lactobacillus, Escherichia coli, Klebsiella pneumoniae, and Candida.

RESULTS

Maternal vagina was colonized mainly by streptococci (67%) followed by lactobacilli (58%) and Candida spp. (39%). Vaginal streptococci influenced the intestinal colonization in infants with staphylococci, C. difficile, and candida.

CONCLUSION

Vaginal lactobacilli influenced colonization with C. difficile, and Candida. Vaginal flora is a potent factor influencing the development of bacterial flora in the neonatal and infantile gut. The extension of the observation period until 3 months of life allow to discover the potential changes in the intestinal flora of children.

Mode of Delivery and Its Influence on the Acquisition of Streptococcus mutans in Infants

INTRODUCTION

Dental caries pose distinct challenges when it comes to determining their microbial etymology. Streptococcus mutans play an important role in dental caries. The aim of the present study was to compare oral microbiota in infants delivered by these different routes. A study was conducted on 40 infants. Swab sample collection was done for the detection of S. mutans. Our study indicated no differences in oral microbiota in infants due to mode of delivery.

AIM

To assess whether infants born through cesarean section delivery or infants born through normal delivery influence the initial acquisition of S. mutans in infants.

SETTINGS AND DESIGN

The study was carried out on the premises of Bharati Hospital, Pune, wherein 40 infants (3-36 months) were enrolled for the study. Two groups were designed. Group I: Infants born with cesarean section delivery Group II: Infants born with normal section delivery.

MATERIALS AND METHODS

Bacterial swab sampling was done in the participants for the detection of S. mutans. Colony-forming units on each plate were determined for the estimation of S. mutans level in oral cavity.

STATISTICAL ANALYSIS USED

Bar diagram analysis and chi-square test were performed to derive p-value.

RESULTS

The p value derived at the end of the study was 0.52. Hence, analysis of data demonstrates no significant influence of cesarean section delivery and normal delivery on oral microbiota development in infants.

CONCLUSION

Initial acquisition of oral S. mutans in infants is not dependent on the mode of delivery.

KEY MESSAGES

Initial acquisition of S. mutans, Mode of delivery.

HOW TO CITE THIS ARTICLE

Ubeja RG, Bhat C. Mode of Delivery and Its Influence on the Acquisition of Streptococcus mutans in Infants. Int J Clin Pediatr Dent 2016;9(4):326-329.

Non-viral microbial keratitis in children

Microbial (non-viral) keratitis is a serious vision-threatening condition. The management of microbial keratitis in children is particularly complicated by the children's inability to cooperate during examinations and the lack of information prior to presentation. Predisposing factors vary according to geographical location and age. Corneal trauma is the leading cause for microbial keratitis in children, followed by systemic and ocular disease. Etiologic agents are most frequently Gram-positive and Gram-negative bacteria commonly found in contact lens-related microbial keratitis. Mycotic keratitis is a major risk factor in tropical weather conditions, particularly when associated with agricultural trauma. Early diagnosis, intensive drug treatment, and timely planned surgical intervention may effectively improve the outcome of pediatric microbial keratitis.

Clinical significance of Credé's prophylaxis in germany at present

The introduction of silver nitrate for prophylaxis of gonococcal ophthalmia neonatorum is one of the milestones of preventive medicine. However, in our time an increasing necessity to review Credé's prophylaxis from both a human rights and a medical standpoint is required. The chairmen of the obstetrics and gynecology departments of the German university hospitals were questioned to learn about their policy and experience. Data were provided by 22 of 28 consulted institutions, representing 31,700 annual deliveries seen over a mean period of 5.5 years. Ocular prophylaxis was in use in 16 (73%) of the reporting hospitals (1% silver nitrate in 14 and gentamicin in 2). A nonspecific conjunctival reaction occurred in 5-10% of the newborns, but no major side effects were seen. Non-gonococcal ophthalmia neonatorum was observed in less than 0.1%; however, institutions without a preventive policy reported up to a 5% incidence of neonatal conjunctivitis, mostly due to Staphylococcus aureus, as well as Neisseria gonorrhoeae in two newborns. Application of silver nitrate is considered a necessary prophylactic measure and safe if it is properly administered. However, major efforts should be directed toward its replacement by alternative antiseptic substances as well as toward chlamydial screening and therapy in pregnancy.

Acute bacterial conjunctivitis

Acute bacterial conjunctivitis is the eye disease most commonly seen by general practitioners, and is estimated to represent approximately 1% of all consultations in primary care. This article gives a review of the epidemiology, aetiology, clinical picture, complications, differential diagnoses, in vitro examinations and therapy of acute bacterial conjunctivitis. Until now, topical antibacterial therapy has generally been preferred by both physicians and patients because this will usually shorten the course of the disease slightly and allow the early readmittance of children to their kindergarten or school. Recently, several reports from primary care have confirmed the well-known clinical experience that the disorder has an excellent prognosis with a high frequency of spontaneous remission. In accordance, an expectant attitude or delayed prescription policy are now frequently strongly recommended. However, these reports also emphasize the difficulty in making a correct clinical distinction between bacterial and viral conjunctivitis. The effect of a general non-prescription attitude on transmission rates of pathogens also remains to be clarified. This must be born in mind when deciding how these patients should be handled. The socioeconomic and medical pros and cons of different treatment policies are discussed, and a highly personal view on the optimal handling strategy for these patients is also presented.

Mode of delivery and other maternal factors influence the acquisition of Streptococcus mutans in infants

S. mutans plays a key role in dental caries. The extent to which perinatal events influence the acquisition of S. mutans is unclear. We hypothesized that several maternal factors, including the mode of delivery, influence the initial acquisition of S. mutans in infants. A prospective cohort study was conducted in 156 mother-infant pairs. The study found that maternal gestational age (p = 0.04), S. mutans level (p = 0.02), caries score (p = 0.02), sexually transmitted disease (STD) infection experience (p = 0.01), and family income (p = 0.03) had significant effects on the acquisition of S. mutans. Among infants who became infected, those delivered by Caesarean section acquired S. mutans 11.7 mos earlier than did vaginally delivered infants (p = 0.038). C-section infants harbored a single genotype of S. mutans that was identical to that of their mothers (100% fidelity). Analysis of the data demonstrated the possible perinatal influences on infants' acquisition of a member of the cariogenic microbiota, and its potential effect on caries outcome.

Normal ocular flora in newborns delivered in two hospital centers in Argentina and Paraguay

PURPOSE

To determine the spectrum of normal conjunctival flora in newborns in two hospital centers in North Argentina and Paraguay.

METHODS

In this prospective observational study, conjunctival specimens were obtained from the right eyes of newborns prior to the application of any topical medications. Culture samples were also obtained from the cervicovaginal secretions of the infants' mothers. All samples were directly inoculated into culture media and all growth were identified and quantified.

RESULTS

Among the 190 newborns studied, 126 were delivered vaginally and 64 via caesarean section (C-section). A total of 180 different bacterial strains were acquired from the vaginally delivered infants and 77 from the C-section group (P=0.078, Student's t-test). Conjunctival cultures obtained within one hour of birth showed that 85 out of 101 samples (84%) from both the vaginal and C-section group had positive cultures, compared to 84 out of 89 samples (94%) obtained more than 1 h after birth (P<0.001). Among the vaginally delivered newborns, the most common bacteria isolated were coagulase-negative Staphylococcus (in 69 samples, 38%), Propionibacterium spp (36, 20%) and Corynebacterium spp (29, 16%). In the CES, the most common isolates were coagulase-negative Staphylococcus (39, 51%), Propionibacterium spp (22, 29%) and Staphylococcus aureus (6, 8%). There was a significantly higher proportion of gram-positive rods (P=0.017) isolated from infants delivered vaginally (16%) than from those delivered by C-section (5%). No Neisseria gonorrhoeae were isolated in conjunctival samples. Among the 130 organisms isolated from cervicovaginal secretions in 81 out of 189 mothers, the most common organisms were Lactobacillus spp. (47%), Corynebacterium spp (21%), Gardnerella vaginalis (15%), and Candida spp (14%). No Neisseria gonorrhoeae or Chlamydia trachomatis were found in cervicovaginal samples.

CONCLUSION

The most common conjunctival bacteria in newborns delivered by either vaginal birth or C-section were coagulase-negative Staphylococcus. The proportion of positive conjunctival cultures was higher for infants delivered vaginally than for C-section delivery.

Corneal ulceration in pediatric patients: a brief overview of progress in topical treatment

Pediatric microbial keratitis is a rare but potentially devastating condition. The condition is similar to adult microbial keratitis, but is often characterized by a more severe inflammatory response. The micro-organisms that cause microbial keratitis in children are similar to the causative agents in adults, with herpes simplex and bacteria being the predominant causative agents, and fungi being less frequent. Of the bacterial pathogens, Pseudomonas aeruginosa, Staphylococcus aureus and alpha-hemolytic streptococci are common. The risk factors for pediatric keratitis include colonization of the eyes during birth and trauma to the cornea. Certain microbial factors involved in microbial keratitis are common to all micro-organisms, including adhesion to the cornea, penetration into the cornea, destruction of the corneal stroma (usually by microbial and/or host proteases), and recruitment of white blood cells to help defend the eye. Specific inflammatory responses that occur during pediatric microbial keratitis are not known in detail, but it is likely that cytokines and polymorphonuclear leucocytes are major factors, as they are in adult microbial keratitis. Treatment for pediatric microbial keratitis is usually the same as treatment for adult microbial keratitis; topical application of antimicrobial agents initially, followed by application of anti-inflammatory agents. With pediatric microbial keratitis, extra care must be taken to ensure nontoxicity due to blood adsorption. New microbial keratitis treatments are being developed and these mainly focus on new antimicrobials, antivirulence agents (such as vaccination against microbial toxins) or specific anti-inflammatory agents. There remains a clear need for increased research into the specific responses during microbial keratitis in children which will help progress new therapies as well as the development of new antimicrobials, especially new antifungal therapies.

Gonococcal scalp abscess in a neonate delivered by caesarean section

Gonococcal infection in caesarean delivered babies is very rare and is usually limited to ophthalmia neonatorum. The mother had rupture of membranes 14 hours before the caesarean section. The infection was most likely introduced by the fetal scalp electrode probes applied 2 hours before delivery. This is the first reported of a neonatal gonococcal abscess in a caesarean delivered infant.

Povidone-iodine for ophthalmia neonatorum prophylaxis

PURPOSE

The agents currently used to prevent ophthalmia neonatorum are less than optimal, with reports indicating evidence of bacterial resistance, ineffectiveness, and toxicity. Povidone-iodine ophthalmic solution, which has been shown to be effective in the preoperative preparation of the eye, generates no resistance, is an effective antimicrobial agent, and has low toxicity. We evaluated the effectiveness and safety of povidone-iodine for ophthalmia neonatorum prophylaxis.

METHODS

A bacterial culture was taken from the conjunctiva of each eye of 100 infants within 30 minutes of birth. A drop of 2.5% povidone-iodine solution was then placed on one eye, while the other eye received either one drop of silver nitrate 1% ophthalmic solution or 0.5% erythromycin ointment. Conjunctival bacterial cultures were again taken two to four hours after birth. At each culture and at 24 hours after birth, the eyes were examined for toxic changes. To measure the effectiveness of the medications, the number of bacterial colony-forming units and species from each culture was compared.

RESULTS

All three agents significantly reduced the number of colony-forming units, but povidone-iodine caused the most significant decrease. The number of species was reduced significantly by povidone-iodine (P = .00051) and silver nitrate (P = .007), with povidone-iodine yielding the most significant decrease. Erythromycin did not significantly reduce the number of species. Silver nitrate demonstrated more ocular toxicity at the 24-hour determination point than did either of the other two medications (P < .001).

CONCLUSIONS

Povidone-iodine 2.5% ophthalmic solution is an effective antibacterial agent on the conjunctiva of newborns and causes less toxicity than silver nitrate.

A comparison of silver nitrate with erythromycin for prophylaxis against ophthalmia neonatorum

Although prophylactic eyedrops to treat ophthalmia neonatorum is mandated nationwide, states and hospitals are free to choose specific drugs. To compare two of these agents, we studied the incidence and characteristics of ophthalmia neonatorum in two UCLA teaching hospitals over a five-year period. One, which used 1% silver nitrate solution exclusively, had 50 cases in 34,772 births, a frequency of 0.14%. The other used 0.5% erythromycin ointment exclusively and had 43 cases in 12,652 births, a frequency of 0.34%. Ophthalmia neonatorum was more frequent in the hospital using erythromycin (p less than 0.001), as was chlamydial conjunctivitis (p less than 0.02). Although not statistically significant, gonococcal conjunctivitis was found in four infants, all in the hospital using silver nitrate. Because silver nitrate was found more effective in decreasing the total frequency of all cases of ophthalmia neonatorum, and cases caused by Chlamydia and gram-negative bacteria specifically, this drug still should be considered as a primary prophylactic agent against ophthalmia neonatorum.