Pathogenic bacteria and their antibiotic sensitivity in ophthalmia neonatorum.

CONTEXT: Emergence of coagulase-negative staphylococci as pathogens in ophthalmia neonatorum. AIMS: To analyze the bacteriological spectrum of ophthalmia neonatorum and its associated risk factors. SETTINGS AND
DESIGN: Retrospective analysis in a tertiary care hospital in India. SUBJECTS AND METHODS: A retrospective review was performed in a tertiary care center in India on 139 neonates presenting with conjunctivitis over a period of 3 years. All the neonates presenting to the out-patient department, those admitted in the Neonatal Intensive care Unit and in-patient wards were included in our study. The neonates were clinically examined and followed-up by a single experienced ophthalmologist. Details including demographic data, age of the infant, type of delivery, investigations, and treatment outcomes were analyzed. STATISTICAL ANALYSIS USED: Frequency calculation using Microsoft Excel for windows 10.
RESULTS: In the 92 samples with growth (66.2%), the most common organisms isolated were coagulase-negative Staphylococci (35.9%), Klebsiella pneumoniae (16.3%), and Acinetobacter species (16.3%). Others were Staphylococcus aureus (14.1%), Pseudomonas aeruginosa (8.7%), and Escherichia coli (8.7%). Ophthalmia neonatorum was significantly higher in preterm infants born out of lower-segment cesarean section and those requiring ventilatory support.
CONCLUSIONS: Unlike gonococcus, which is implicated in ophthalmia neonatorum, our study shows varied microbiological spectrum and sensitivity patterns with coagulase-negative staphylococci as the key pathogen. The role of coagulase-negative staphylococci as a disease-causing pathogen becomes increasingly important with an imperative need for prudent use of common antibiotics in treating these pathogenic bacteria. Copyright:

Introduction

Ophthalmia neonatorum or neonatal conjunctivitis occurs in the 1st month of life and remains an important cause of ocular morbidity and blindness among the infants in the developing nations. The causes of neonatal conjunctivitis are chemical inflammation, bacterial infection, and viral infection. In developing countries, majority of the infectious cases are due to bacteria.[1] The most common bacteria include sexually transmitted agents (Neisseria gonorrhea and Chlamydia trachomatis) from the mothers and skin commensals (Staphylococcus aureus).[2]

The organisms are thought to infect the infant from the birth canal of the mother, although some may get infected from their immediate surrounding. The predisposing factors for the infant include premature rupture of membranes and prolonged labor.[3]

The aim of our study was to identify the bacterial spectrum of neonatal conjunctivitis, antibiotic sensitivity patterns, and the risk factors associated with it.

Subjects and Methods

Study population

One hundred and thirty-nine infants presenting with neonatal conjunctivitis were included in this study. A retrospective review was performed for a period of 3 years at a tertiary care center in Chennai. The demographic features, clinical features, treatments, and outcomes of the therapy were all reviewed. All the infants presenting to the Outpatient Department, those admitted in Neonatal Intensive Care Unit, and those in postnatal ward underwent a complete ophthalmic examination by a single experienced ophthalmologist. A diagnosis of clinical conjunctivitis was made based on conjunctival congestion, lid edema, and the type of eye discharge. Details of the new-born including age, birth weight, and the type of delivery were noted. A detailed history from the mothers was obtained to exclude the history of sexually transmitted diseases.

Specimen collection

Informed consents were obtained from the mothers and conjunctival specimens from the infants were taken using sterile cotton-tipped swabs for gram staining, bacterial culture, and antibiotic sensitivity. The swabs were transported to the laboratory in a sterile stoppered vial and were cultured immediately. They were cultured on blood agar, chocolate agar, and thioglycolate broth at 37°C. A negative culture report was made after there was no growth in the inoculated plates and tubes for a minimum of 48 h. Appropriate antibiotic sensitivity testing was done using Kirby Bauer's Disc Diffusion method.

Management

The eyes of the neonates after birth were cleaned with sterile normal saline and there was no history of any prophylactic antibiotic drops instillation. After a diagnosis of clinical conjunctivitis was made, the infants were started on broad-spectrum antibiotics and switched to appropriate antibiotic drops based on the culture and sensitivity reports. They were followed up for a period of 2 weeks after which there was no residual infection in any of the infants.

Results

Eighty-six babies (61.8%) were male and fifty-three (38.1%) were female. The mean age of the neonates was 2.2 days, with a range of 1–21 days. The mean weight of the infants was 2345.12 g (1800–3500 g). Forty-one babies were term (29%) and the remaining ninety-eight babies were preterm (71%). One-hundred babies (72%) were delivered by emergency Lower Segment Cesarean Section (LSCS) and thirty-nine babies (28%) were born through normal vaginal delivery. Ninety-six preterm babies were born by emergency LSCS (69.06%) and four-term babies (2.87%) were born by emergency LSCS. Emergency LSCS was performed due to the following reasons-Preterm Rupture of Membranes (PROM) (94%) and preeclampsia (2%) in preterm infants; Meconium aspiration (4%) in term infants. In 109 babies (78%), the conjunctivitis was unilateral and in 30 (22%) it was bilateral. Furthermore, 135 of the 139 infants developed conjunctivitis within 1–5 days after birth. Other four infants developed conjunctivitis between 7 and 21 days after birth. All the 96 preterm infants born by emergency LSCS had a low Apgar score for which ventilatory support was provided for a varied amount of time.

Microbial pattern

Bacterial growth was detected in 92 samples (66.2%) of the 139 samples. All the infants had a mucopurulent type of conjunctivitis. None of the infants had any preauricular lymphadenopathy. There was no corneal involvement in any of them. None of the mothers had any history of sexually transmitted diseases. The organisms isolated were coagulase-negative staphylococci (35.9%), Klebsiella pneumoniae (16.3%), and Acinetobacter species (16.3%) [Table 1]. Other organisms isolated were S. aureus (14.1%), Pseudomonas aeruginosa (8.7%), and Escherichia coli (8.7%). Growth was not detected in 47 samples (33.8%). The antibiotic sensitivity pattern is shown in Table 2.

Table 1

Bacterial growth pattern

Bacteria	n (%)
Acinetobacter species	15 (16.3%)
Coagulase-negative staphylococci	33 (35.9%)
Escherichia coli	8 (8.7%)
Klebsiella pneumoniae	15 (16.3%)
Pseudomonas aeruginosa	8 (8.7%)
Staphylococcus aureus	13 (14.1%)

Table 2

Antimicrobial sensitivity pattern of the isolated bacteria

	Ami.	Cef.+Sul.	Ceph.	Cip.	Cli.	Gent.	Pip.+Taz.	Toba.	Van.
Acinetobacter species (%)	40	80	-	26.6	-	-	40	-	100
Staphylococcus aureus (%)	-	-	69.2	61.5	69.2	53.8	-	-	100
Klebsiella pneumoniae (%)	-	80	13.3	70	-	-	93	87.5	-
Pseudomonas aeruginosa (%)	-	100	100	100	-	-	100	-	-
Escherichia coli (%)	75	50		0			100	75
CoNS (%)	-	-	33.3	24.2	36.4	24.4	-	-	100

CoNS: Coagulase-negative Staphylococci, Ami.: Amikacin, Cef.+Sul.: Cefaperazone + Sulbactum, Ceph.: Cephotaxime, Cip.: Ciprofloxacin, Cli.: Clindamycin, Gent.: Gentamycin, Pip. + Taz.: Piperacillin + Tazobactum, Toba.: Tobramycin, Van.: Vancomycin

Discussion

Ophthalmia neonatorum remains a significant cause of ocular morbidity in developing countries, though its occurrence has diminished to exceptionally low levels in the developed nations. The results of our study showed no growth of gonococcus which is one of the leading causes of ophthalmia neonatorum. Coagulase-negative staphylococci, Klebsiella pneumoniae and Acinetobacter species were the most common bacteria isolated from our study. Comparable bacterial growth pattern were also observed by others.[4] Since there was no instillation of prophylactic antibiotic drops after delivery, the cause for conjunctivitis in our study could not have been due to chemicals. Chlamydia as a cause of conjunctivitis was ruled out clinically in our study because all the infants had conjunctivitis within 1–5 days after birth, there was no pseudo-membrane formation, and there was no history of sexually transmitted diseases among the mothers. Viral conjunctivitis was also ruled out by the lack of watery discharge and absence of preauricular lymphadenopathy. Nasolacrimal obstruction was ruled out because of an absence of watering and negative Regurgitation on pressure over the lacrimal sac test among the infants. Our study stresses the increased incidence of coagulase-negative staphylococci as pathogens. These bacteria normally considered as commensals have increasingly become pathogenic due to their high affinity for foreign materials such as ventilators, masks, and catheters which are an integral part of modern medicine. Furthermore, our study shows a high incidence of bacterial conjunctivitis in preterm infants born out of emergency LSCS. The attributable cause of bacterial conjunctivitis in these infants born out of emergency LSCS was due to early rupture of the membranes and prolonged labor. The additional risk in these preterm infants could be assigned to their immature immune system and the requirement of ventilatory support which could harbor the normal commensals. Finally, our study highlights the changing pattern of bacteriological growth in infants with ophthalmia neonatorum. Similar antibiotic sensitivity patterns were noted and confirmed by others.[5]

Our study has several limitations. First, we may not have identified all the possible clinical cases. There is also a lack of standardized recording process because of which, all the risk factors might not have been identified. Third, the swabs were not taken in the normal eye and assessed for the microbial growth pattern. Despite these limitations, it is possible to draw several important conclusions, the most important being the advent of coagulase-negative staphylococci as pathogens in infants with immature immune systems and those on ventilatory support. The antibiotic sensitivity pattern among the microbes shows the urgent need for sensible use of antibiotics to control the emergence of antibiotic-resistant strains.

Conclusions

Our study emphasizes the need for the careful use of antibiotics due to the increased prevalence of bacteria resistant to many common antibiotics. It underscores the prominence of dependent ventilatory support as an important risk factor among preterm infants for developing neonatal conjunctivitis associated with coagulase-negative staphylococci. Hence, newer studies are necessary to identify and establish specific virulence factors for coagulase-negative staphylococci as their role as pathogens become increasingly important.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.