Bacterial conjunctivitis is the most common eye disease of newborns, the pathogens were reported inconsistent due to epidemiological variations in different countries and may change over time in the same location. Compared with other infectious diseases, there was few investigation on neonatal conjunctivitis because of it was self-limiting disease[8]. However, delayed treatment or lack of attention can have serious consequences for the health of newborns. In this study, we retrospected the clinical and microbiological data of neonates with positive blood cultures for bacteria conforming neonatal conjunctivitis from January 2017 to December 2021 in Guangzhou.
For the isolation rates of bacterial-culture positive cases, we suggested an overall isolation rate of 30.9%, 21.6% for gram-positive and 9.9% for negative-positive infections during our study period. Previous study has reported that the trend of decreasing Gram-positive bacteria and increasing Gram-negative bacteria in the conjunctival sac secretions from neonatal bacterial conjunctivitis from 2002 to 2016 in Shenzhen, another city in China [9]. However, we suggested an increasing trend of gram-positive bacteria cases from 2017 to 2021, and we failed to observe a trend Gram-negative group. Interestingly, the patient numbers have dropped dramatically from 2020 to 2021 because of the SARS-CoV-2 epidemic, but the pathogen detection rate was significantly higher than before. The number of patients got tested in 2020 and 2021 was noticeably decreased might due to COVID-19 pandemic outbreak and the restrictive measures responsive to COVID-19 [10]. And there were fewer patients came to visit clinicians after delivery, especially for the neonates with mild symptoms. We also investigated the clinical characteristic between gram-positive and gram-negative pathogens infected patients with limited populations. Our findings suggested that those neonates who experienced turbid amniotic fluid and under seven days were more likely suffer gram-negative bacterial infection.
Historically, N. gonorrhoeae was one of the major causes for serious consequences in neonatal bacteria conjunctivitis. The prevalence of N. gonorrhoeae depends on the population studied, standards of hygiene, and use of prophylactic perinatal topical antibiotics. According to our results, only one case caused by N. gonorrhoeae was found. The screening practice and prophylactic medicine before delivery might contribute to this low rate of N. gonorrhoeae [11]. Furthermore, over half of the ocular isolates were S.aureus (53.7%) in the present study, this result was similar with some recently researches. The detection rate of S. aureus was range from 27.6–67.9% of neonatal conjunctivitis in different regions or countries [9, 12, 13]. For example, a 5 year retrospective review in Southwest China also suggested that S. aureus (29%) is the most common pathogen of severe neonatal conjunctivitis [5]. Previous study reported that S. aureus are related to all kinds of eye infections, and are the main causative agents of these infections [14]. Moreover, Hoppe PiaAlice et al reported Panton-Valentine Leukocidin expressing strains of S. aureus was associated with pediatric recurrent periorbital infections and conjunctivitis [15]. Therefore, we also suggested that S. aureus should be consider as a major pathogen for neonatal bacterial conjunctivitis.
Moreover, C. macginleyi (10.7%) and E. coli (10.1%) are another common pathogens followed by S.aureus in the present study. This result was different from prior researches, and they report that S. aureus and S. viridans identified as the another common gram-positive pathgens in neonatal bacterial conjunctivitis. To be notice, the isolated rate of C. macginleyi has shown an increasing trend in our hospital. Corynebacterium species are commonly found in the conjunctiva of healthy adults and are recognized as non-pathogenic bacteria. Recently, C. macginleyi was described as a pathogen isolated from among ocular infections studied in Japan, Canada and North America respectively since 2008 [16–18], but not for newborns. Ahmed R et al. reported a case of C. macginleyi conjunctivitis in 2010 [16]. Joussen et al. reported C. macginleyi in 13 of 107 (12%) cases of culture-positive conjunctivitis, indicating its importance in ocular surface infections, especially in immune compromised hosts [17]. Because of the imperfect development of the immune system and lacrimal glands, newborns are more susceptible to the threat of weakly pathogenic or conditionally pathogenic bacteria in the birth environment. In this regard, the resident or opportunistic pathogens (e.g. C. macginleyi) should be considered as a novel pathogen for neonatal conjunctivitis. For E. coli, an association was observed between E. coli neonatal conjunctivitis and a higher rate of genitourinary infections history in their mothers [13]. In our data, E. coli was the most common Gram-negative bacteria from conjunctivitis samples, and their mean age was 4.8 days, which was statistically significantly younger than the S. aureus infected group. Although their mothers' history of genitourinary infections was not clear in our study, this result suggests that we should pay more attention to perinatal infection, especially for neonates who were under 7 days. These findings were supported by a case report, the features of neonatal conjunctivitis caused by E. coli were onset within the first 3 days of life, normothermia, purulent discharge, and lid edema [18].
In the recent years, the recognition of antibiotic resistance in the pathogenesis of bacterial conjunctivitis has been increasing. However, there still lack knowledge on the neonatal bacterial conjunctivitis. The first line of treatment for neonatal conjunctivitis of bacterial origin involves the use of silver nitrate solution or topical antibiotics such as 1% tetracycline or 0.5% erythromycin eye ointments. In the current analysis of the antimicrobial susceptibility profiles, we found a higher rate of resistance against to penicillin (84.1%), and rates of resistance to clindamycin, erythromycin, and oxacillin exceeding 30%. All strains of S. aureus and C. macginleyi were susceptible to linezolid and vancomycin. The rate of MRSA was 34.2% in our population which was lower than in United States (39%) and India (43%), higher than Italy (24%) [19–21]. The rate of ESBL-positive E. coli was 15.6%. S. aureus, S. pneumoniae, M. catarrhalis and H. influenzae showed high susceptibility to quinolones, which were used topically as first-line empirical treatment in ophthalmology, but the susceptibility rate of C. macginleyi and E. coli to quinolones was only about 50%~60%, the drug susceptibility test result was important for clinical therapeutic effect.
In this study, we conducted a comprehensive investigation to evaluate the bacterial patterns, clinical characteristics and drug susceptibility profiles of neonatal bacterial conjunctivitis from 2017 to 2021. Although we suggested that S. aureus, C. macginleyi and E. coli were the top 3 isolated pathogens in Guangzhou, a multicentre-based retrospective study should be conducted to fully investigate the pathogen spectrum of neonatal bacterial conjunctivitis. In addition, our study was a 5-year retrospective study including 967 neonates, the long-term data collection may be more reliable to demonstrate the change of neonatal bacterial conjunctivitis. Furthermore, molecular characteristic of the pathogens was important for us to understand the pathogenic profile and antimicrobial resistance pattern.