This is the first study from central Indian province of Madhya Pradesh that reports the SBI rates among children. The study addresses a significant concern that general practitioner and pediatricians face while treating children presenting with fever. The study identified factors associated with risk for SBI like unimmunized versus partly immunized status (RR 4.26), breathlessness (RR 1.80), presence of weight loss (RR 2.28), and suspected UTI (RR 1.95), which can be looked for in future studies on fever in hospitalized children.
Equal distribution of sex of the children presenting with fever is naturally expected as was found in our study (Table 3). Almost equal distribution of sex was reported in other studies [21, 22]. Most children with SBIs were in the 3–12 month age group (Table 3). Similar findings were reported in an Indian study, which reported 77% of the children with fever were infants .
None of the patients in our study diagnosed with bronchiolitis presented SBIs. Similar results were reported in children less than 3 months of age . However, most (93%) patients with radiologically confirmed pneumonia had a confirmed SBI. Similar findings were reported in a study in England, wherein 92% of the patients presented microbiologically and radiologically proven pneumonia . However, another study reported low percentages of SBIs in children with pneumonia . In our study, out of the 38 patients presenting with UTI, only 9 (24%) had confirmed SBI. A low proportion of SBI of up to 18%  was reported among children with UTI. However, other studies have reported high SBI rates of 30% and more . In our study, 29/31 (94%) of the children presenting with severe acute malnutrition (SAM) and fever had confirmed SBI. Majority (86%) of the patients presented evidence of bronchopneumonia, followed by sepsis (7%), UTI, and meningitis. A high proportion of bronchopneumonia responsible for SBI in patients with SAM has been reported by other studies from India, Zambia, and East Africa [24–26]. An East African study reported a higher rate of sepsis in patients with SAM than that in the present study . The synergism between malnutrition and infectious disease is well known. Protein and vitamin deficiency inhibit the formation of specific antibodies and also cause impairment of the pulmonary defense mechanism . The increased incidence and severity of infections in malnourished children is due to limited production and diminished functional capacity of B-cell and T-cell components of the immune system . In our case series, of the 25 patients with simple febrile convulsion, only 1 (4%) had confirmed SBI. A similar low risk for SBI in first-time seizures was reported .
One of the problems we faced in the diagnosis of enteric fever was a low rate of culture positivity (19%). Low rates of culture positivity in suspected enteric fever has been reported from other tertiary care hospitals in India. The main cause for such low rates is antibiotic use prior to culture .
Compared with patients without SBIs, those with confirmed bacterial infections require a longer hospital stay; this has been reported in our study  and other settings . A history of previous hospitalization increased the odds for SBI 15-fold (Table 2). Another study reported a 3-fold increase in the risk of SBI in patients with a history of hospitalization . Furthermore, SBI risk in chronic diseases, such as tuberculosis, HIV infection, and diabetes, was reported . As observed in this study, the increased risk of SBI in partially immunized or unimmunized children compared with fully immunized children have been reported earlier [21, 22]. The chances of infection were the least among adolescents who were fully immunized (9.1%) compared with unimmunized children (33.7%) . Our study found that children with developmental delay had increased risk of SBI. A study showed that 70% of the children with developmental delay had SBI . Possible reasons could be a lack of verbal ability in developmentally delayed children and nonspecific nature of presenting complaints of SBI.
Children with bacterial infections presented common symptoms, such as breathlessness in 80%, poor feeding in 75%, irritability in 75%, weight loss in 92%, suspected UTI in 79%, and common cold in 71% patients (Table 4). A high prevalence (50%-64%) of respiratory symptoms in children with SBI has been reported [32, 33]. Up to 78% of febrile children reported SBI with poor feeding and 76% children reported SBI with irritability . Suspected UTI was reported as the main presenting complaint in approximately 70% of the patients diagnosed with SBI . A sick-looking child is a common general examination finding in children with confirmed bacterial infections [19, 32, 34]. In our study, on general examination, we observed that 83% of the children who had bacterial infection had no BCG scar mark. Another Indian study  observed that 60% of the children with bacterial infection were without BCG scar mark.
Hyponatremia, hypokalemia, and hypocalcemia were reported in sick children . However, studies reporting SBI and electrolyte abnormalities are lacking . Abnormal leucocyte counts have been reported in other studies as an indicator for SBI [22, 37].
Common pathogens identified in the present study are similar to those reported by other studies [5, 8, 38–42]. However, the prevalence of extended-spectrum beta-lactamase and multidrug-resistant pathogens was high but should be interpreted with caution in view of the small sample size. The problem of antimicrobial resistance has been documented in many settings including India, where many reports of high prevalence of antibiotic-resistant bacteria have emphasized commensal bacteria  as well as pathogenic bacteria .