Is it really a study of community-acquired bacterial infections?

Dear Editor,

I read the article by Bharathi et al. with interest.[1] I wish to point out the following observations.

The authors have titled their study as “Etiology and antibacterial susceptibility pattern of community-acquired bacterial ocular infections in a tertiary eye care hospital in South India.” However, they have not mentioned any inclusion or exclusion criteria in their study to diagnose “community-acquired” bacterial ocular infection. Community-acquired infection is an infection that was present or incubating at the time of hospitalization and was not caused by an organism acquired during previous health care.[2] Centre for Disease Control has laid down the criteria for diagnosis of community-acquired methicillin-resistant Staphylococcus aureus (CA-MRSA) infection [Table 1].[2] Community-acquired infections are commonly caused by Staphylococcus aureus, Streptococcus pneumoniae, Escherichia coli, Klebsiella and Proteus. This criterion can be applied for any species of bacteria or in general bacterial infection. This study was done at a tertiary eye care hospital; therefore, there is large number of referred patients who had been already treated in the past in health care settings elsewhere. Patients treated elsewhere in the past are not fulfilling the above criterion. Community-acquired infection is different from hospital-acquired infection in terms of epidemiology, antibiotic sensitivity patterns, virulence, clinical presentation, and treatment.[2]

Table 1

Criteria for probable diagnosis of infection caused by the community–acquired methicillin-resistant Staphylococcus aureus

The authors have not mentioned about the method of specimen collection in orbital cellulitis patients. Positive culture yield in their study was 42.9% (9 out of 21). Liu et al. reported 74% positive local culture yield in their study.[3] I feel this low positive culture yield may be due to the incorrect selection of site/method of specimen collection. Sinusitis is the most common cause of orbital cellulitis in adult population. The ethmoidal sinus is the most frequently involved sinus in orbital cellulitis secondary to sinusitis. There are multiple factors for the spread of ethmoidal sinus infection to orbit, such as close proximity, very thin medial wall of orbit, various foramina in medial wall for neurovascular bundles and natural dehiscence in lamina papyracea. Therefore, collection of discharge from the inferior meatus of the nose is crucial for culture of pathogenic organisms in orbital cellulitis.

A part of this study was also published in the past.[4] There are few disparities in these two similar studies conducted by the same ophthalmic center. In the present study, the authors mentioned the total number of orbital cellulitis cases over a period of 6 years to be 21. On other hand, a part of the study published elsewhere shows the number of orbital cellulitis cases in a single year to be nil [Table 2].[5] The authors should explain why this disparity has developed.

Table 2

Orbital and ocular adenexal infection in the present study and previously published study