Pneumonia is the single largest killer of children less than five years of age worldwide [1]; though, it is difficult to identify the etiological agents [2]. Nasopharyngeal aspirates can be used for identification of both bacterial and viral pathogens.

Nasopharyngeal colonization with S.pneumoniae usually precedes pneumonia. Though previous Indian studies have reported etiological agents causing pneumonia in children, only a single study reported the results based on culture of nasopharyngeal aspirates [3]. The present study reports the microbiological data from Chandigarh, which is part of IndiaCLEN multicenter study (ISPOT study) on oral amoxicillin in severe community acquired pneumonia (CAP) in children (Clinical trial Registry of India;CTRI/2010/000629).

Nasopharyngeal swabs were collected and standard microbiological techniques were used to isolate S. pneumoniae and H. influenzae. Minimum inhibitory concentration (MIC) of amoxicillin and penicillin were measured by E test according to the manufacturer’s instructions (AB Biodisk, Solna, Sweden). The nasopharyngeal aspirates were obtained soon after nasopharyngeal swabbing and tested for Respiratory Syncytial virus (RSV) antigen using ELISA method (Abbott Testpack for RSV from Abbott Diagnostics, Baar, Switzerland). Blood culture was not collected as stable, ambulatory patients were included.

The collected data were analyzed and tabulated by using the statistical package, STATA software (version 12, college station, Texas, USA). Chi-square test was carried out to test the differences between proportions. P-value <0.05 was considered as significant.

A total of 430 children with severe CAP were screened, and 377 (237 males) were included. The exclusive breast-feeding rate was 66.6% till 6 months of age, and timely complementary feeding was started in 77.4% of children. Immunization status was up-to-date (as per history) in 92.8% children, and 35% children were having mild to moderate malnutrition. Auscultatory wheeze was present in 52% cases, and crackles in 76.6% cases. Infiltrates on chest X-ray was present in 63.9% cases.

Of the 377 nasopharyngeal swab (NPS) and aspirate (NPA) cultures, 27% were negative, 8.5% were positive for both S.pneumoniae and H.influenzae, 28.6% were positive for S. pneumoniae and 9.6% were positive for H influenzae. RSV antigen was detected in 27% cases (Table I). Taking in account mixed infections, S. pneumoniae was present in 56.7% (214/377), H influenzae in 30.2% (114/377), and RSV in 53.3% (201/377).

TABLE I	Frequency of Organisms in Nasopharyngeal secretions in Children with 
Community- acquired Severe Pneumonia 

The rate of isolation of the organisms according to different subgroups is presented in Table II. Regarding S. pneumoniae, the rates of isolation in 3 to <12months vs. 12 to 59 months were significantly different (38% vs. 70%, P=0.026), but the rates did not differ in other subgroups. The rates of isolation of H. influenzae in 3 to <12 months vs. 12 to 59 months (27.8% vs. 72.2%, P=0.039) were significantly different, but the rates did not differ in other subgroups.

TABLE II Organisms from Nasopharyngeal Secretions by Subgroups

Of the 108 S. pneumoniae isolates, 20.4% were susceptible to co-trimoxazole, 31.5% to tetracycline, and 100% to ampicillin, erythromycin, cefotaxime, and ciprofloxacin. Of the 36 H. influenzae isolates, 27.8% were susceptible to co-trimoxazole, 38.9% to tetracycline, and 100% to ampicillin, erythromycin, cefotaxime, and ciprofloxacin.

In the present study, the most common organisms isolated/detected from nasopharyngeal swab (NPS) and aspirate (NPA) cultures were S. pneumoniae and RSV. All the isolates of S. pneumoniae and H. influenzae were susceptible to ampicillin, erythromycin, cefotaxime, and ciprofloxacin.

Limitations of present study include: only children presenting to the health facility were recruited, only nasopharyngeal aspirate was used to identify the organisms, a single center data was presented, and some other organisms were not studied for identification. As the carriage of an organism does not necessarily correlate with the etiology of the pneumonia, non-inclusion of simultaneous age-matched controls is also a limitation. The details of vaccines received by children were also not studied.

Present study results are consistent with some previous results from India. The rate of isolation in previous Indian studies for S. pneumoniae was 9% to 40%, for RSV was 13% to 25%, and for H. influenzae was 7.6% to 22.7% [2,3,6-12]. Present study also noted a higher carriage rate of the organisms in the 12-59 months age group compared to the infants (<12 months), and there was no sex predilection. It has been debated that nasopharyngeal colonization may or may not translate into disease itself. Though this is true, studies have shown nasopharyngeal colonization to be a risk factor for development of pneumonia. In a study from China, compared to controls, the isolation of S. pneumoniae was more in children with radiologically-confirmed pneumonias [13].

Previous Indian studies [7,14,15] have shown the susceptibility pattern of both the organisms as follows: S. pneumoniae being sensitive to penicillin/ampicillin (65%-98.7%), co-trimoxazole (9.1%-81.8%), chloramphenicol (83.4%-94.6%), tetracycline (39.2%), erythromycin (87.5%-89.1%), and ceftriaxone (85%-100%). H.influenza being sensitive to penicillin/ampicillin (59%-81.1%), co-trimoxazole (32.7%-48%), chloramphenicol (45%-81.5%), tetracycline (75%), erythromycin (72.4%), and ceftriaxone (100%). Present study found 100% susceptibility rate of both the organisms to ampicillin, erythromycin, cefotaxime, and ciprofloxacin.

Future research should focus on comparing the organisms isolated from healthy children to those having pneumonia. Simultaneous blood culture to know the exact etiology/pathogenecity of the organism isolated, newer methods of isolation of organisms, serotyping of the bacterial isolates, and testing of additional bacterial isolates should be done to facilitate future policy decisions regarding management of pneumonia in under-five children.

Acknowledgements: Dr Archana Patel, Department of Pediatrics, Indira Gandhi Government Medical College, Nagpur, and Dr Sadbhawna Pandit, Department of Pediatrics, Government Multispecialty Hospital, Chandigarh, for providing logistics and technical assistance for conducting the study.

Contributors: AA and RRD: collected data; PR: performed laboratory tests; RRD, MS, AA and NJ: analyzed data and wrote the manuscript. All authors reviewed and decided to submit the manuscript for publication. MS will act as guarantor of the study.

Funding: IndiaCLEN, USAID and MCH-STAR.

Competing interest: None stated.