True prevalence of shigellosis in Indian children with acute gastroenteritis: have we been missing the diagnosis?

Background: shigella is responsible for high morbidity and mortality among children, yet its true prevalence remains inconclusive. The aim of this study was to determine the actual prevalence of Shigella infection in childhood diarrhea and dysentery cases and assess the applicability of ipaH gene PCR in Indian settings

Methods: this study was conducted at Maulana Azad Medical College and associated Lok Nayak Hospital, New Delhi, India during 2011-12. A total of 385 children [207 with diarrhea, 118 with dysentery, and 60 matched controls] were enrolled. Stool samples were cultured, and the suspected colonies were analyzed using biochemical reactions and serotyping. Antimicrobial susceptibility testing was done using disc diffusion method. ipaH-gene PCR was performed directly on stool samples collected from 180 randomly selected patients [60 from each group]

Results: shigella was isolated using conventional culture methods in 8.2% [95% CI: 5.1%, 12.8%], 33.1% [95% CI: 25.2%, 42.0%], and 0% in the diarrhea, dysentery and control cases, respectively. High resistance was seen towards co-trimoxazole, nalidixic acid, fluoroquinolones, doxycycline and several beta-lactams drugs. Actual prevalence of shigellosis was determined using ipaH gene PCR to be 18.3% [95% CI: 10.4% - 30.1%] diarrhea cases and 56.7% [95% CI: 44.1, 68.4%] dysentery cases. One [1.7%, 95% CI: 0.01%, 9.7%] control specimen also yielded positive result in PCR

Conclusions: correct diagnosis of shigellosis is essential to start antimicrobial therapy in selected cases. The prevalence of Shigella / EIEC infection in children is much higher than previously estimated. Despite its high costs and other limitations, we recommend the use of ipaH-gene PCR as a routine tool in the management of childhood acute gastroenteritis cases

Respiratory syncytial virus in lower respiratory tract infections

Acute lower respiratory infections lead to high morbidity and mortality rates in children from developing countries. The aim of this study was to look into the extent of respiratory syncytial virus infections in children with special reference to the role of specific immunoglobulins in protection against infection as well as the association with bacterial pathogens. Nasopharyngeal aspirates were tested for respiratory syncytial virus antigen by enzyme immunoassay and IgA antibodies by single radio immunodiffusion test. Viral culture on HEP-2 cell system and bacterial culture was done. Sera were tested for detection of antibodies to respiratory syncytial virus by indirect fluorescent antibody test. Antigens of streptococcus pneumoniae and haemophilus influenzae were detected in serum and urine by latex agglutination assay. Incidence rates of acute lower respiratory infections were highest in infants; bronchiolitis and bronchopneumonia being the main contributors. Respiratory syncytial virus infection was found in 27.08% of the cases. Secretory IgA antibodies level was found to be a good indicator of respiratory syncytial virus infection as seen by the significantly higher levels in cases as compared to both non respiratory syncytial virus cases and controls

Relationship of IgG avidity index and IgM levels for the differential diagnosis of primary from recurrent cytomegalovirus infections

Since the incidence of symptomatic congenital cytomegalovirus infection is low [0.05%] and risk factors are not well defined, it is difficult to develop strategies for prevention. The aim of this study was to recognise the utility of specific Immunoglobulin G avidity analysis for distinguishing primary infection from past/recurrent infection. Sera from 50 women with cytomegalovirus specific Immunoglobulin M antibodies without proven seroconversion and infants born to these women were tested for presence of Immunoglobulin M antibodies by commercial enzyme immunoassay. For cytomegalovirus specific immunoglobulin G avidity, sera were measured by commercial kit according to manufacturer's recommendations. Among 50 sera form mothers, 26 showed the presence of Immunoglobulin M antibodies out of which 15 had low avidity antibodies. Out of 50 sera from children, 18 showed the presence of Immunoglobulin M antibodies. Out of these 18 sera from children, 12 were symptomatic, which all showed the presence of low avidity antibodies. The results showed that an avidity index<40% and presence of Immunoglobulin M antibodies is highly suggestive of a recent primary infection