nspA Gene as a specific genetic marker for detection of Neisseria meningitidis causing bacterial meningitis.

Bacterial meningitis caused by Neisseria meningitidis which causes human brain meninges damage, is generally diagnosed from patient cerebrospinal fluid through microscopy, immunological assays, biochemical test, PCR, microarray and biosensors. However, these methods are expensive, time-consuming or non-confirmatory due to certain limitations. A quick PCR based method was developed for detection of bacterial meningitis caused by N. meningitidis using specific primers based on amplification of virulence nspA (Neisseria surface protein A) gene partial sequence (202 bp). The nspA gene amplicon could be used as a genetic marker for minimum detection of 10 ng genomic DNA (G-DNA) of N. meningitidis with high sensitivity only in 80 min, which is least time reported for the confirmation of the disease. However, the lower detection limit was found as low as 1.0 ng G-DNA, but with less sensitivity. The cross-reactivity of the genetic marker was also studied with other possible pathogens. A comparison with the presently available detection methods and our method was also done using patient samples.

Glycoprotein B Genotyping in Congenital/perinatal Cytomegalovirus Infection in Symptomatic Infants.

Background: Molecular epidemiological studies on circulating strains of CMV in cogenital/perinatal infections have not been done earlier in this region. Objective: To study the glycoprotein B genotypes in babies with symptomatic congenital/perinatal CMV infection and to assess the possible influence of genotype on the outcome of the infection. Methods: Clinical samples (blood and urine) of symptomatic babies are sent to the Virology Department of NCDC, Delhi for the diagnosis of congenital infections. 375 clinical samples of infants (newborn - 6 months old) were included for the study. Serum samples were subjected to ELISA for detection of IgM antibodies against CMV. DNA isolation and amplification of CMV genomic DNA targeting gB gene fragment by nested PCR, was carried out in the samples. The amplified fragment including the cleavage site was subjected to RFLP using restriction enzymes Rsal and Hinf1. They were also verified by sequencing using Big Dye Terminator chemistry. Results: 75 samples out of 375 tested were confirmed positive for CMV infection by serology and PCR. Both RFLP and sequencing of gB gene fragment showed that gB 1, 2 and 3 genotypes were in circulation. gB 3 was the most prevalent genotype in symptomatic infants. Hepatosplenomegaly was the most common feature in gB-3 genotype of CMV. gB2 congenital CMV infection was more commonly associated with long term sequelae.

Atypical Subacute Sclerosing Panencephalitis With Short Onset Latency.

An 11-month-old boy presented with focal seizures, myoclonic jerks and altered sensorium of one month duration, with a history of measles at eight months of age. A diagnosis of Subacute sclerosing panencephalitis (SSPE) was made on the basis of typical EEG changes and presence of anti-measles antibody in cerebrospinal fluid. A differential diagnosis of SSPE should be considered in all forms of acute encephalopathy in infants for early diagnosis and management.

Emergence of pandemic 2009 influenza A H1N1, India.

Background & objectives: Pandemic H1N1 caused deluge of cases from 74 countries and prompted World Health Organization to raise warning to phase 6. The present study was conducted on throat and nasal swab samples received and tested at National Centre for Disease Control, Delhi, India during 2009-2010 to collect epidemiological and clinical information on positive cases. Methods: Throat and nasopharyngeal swabs from category C influenza A H1N1 patients during May 2009-September 2010 along with their clinico-epidemiological details were collected from identified hospitals from Delhi and other States. Samples were tested by Real time reverse transcriptase PCR using primers and probes developed at CDC, Atlanta for four influenza target genes. Results: A total of 33,751 samples, both throat and nasal swab samples from each patient were tested for H1N1 influenza virus, of which, 7943 (23.5%) were positive for pandemic influenza A H1N1 and 3759 (11.1%) were positive for influenza A (seasonal flu). Maximum number of positive cases (N=2792, 35.1%) were from 20-39 yr age group, comprising 1790 (22.5%) males and 1182 (14.8%) females. Only 2620 (33%) positive cases were close contact of influenza A H1N1 positive patient. Majority cases presented (N=2792, 35.1%) with fever 7005 (88.1%), followed by 6133 cases (77.2%) exhibiting fever and cough, 377 (4.7%) complained of fever, cough, nasal catarrh and 362 (4.5%) cases had fever with shortness of breath. Interpretation & conclusions: The study showed a peak of cases of pandemic influenza A H1N1 in December 2009 and indicated predominance of H1N1 positive cases among 20-39 yr age group and among males compared to females.

Whole Cell Pertussis Vaccine : Reducing Toxicity.

Since introduction of the pertussis vaccine in 1940’s the morbidity and mortality due to the infection has been markedly reduced all over the world. However the adverse effects of the inactivated whole cell pertussis vaccine like pain, swelling at the site of injection, fever, vomiting anorexia, persistent crying & drowsiness have been the cause of great concern, till date. Also the safety concerns over the use of thiomersal as an inactivating agent as well preservative have been raised in the recent past. Studies in many countries have been initiated to reduce or replace thiomersal & using other inactivating agents in the vaccines. Limited studies have been conducted in India. The present study has been undertaken as an attempt to reduce the quantity of thiomersal and modification in the procedure of production of the pertussis vaccine to reduce the toxicity, to produce better quality of whole cell pertussis vaccine. To achieve this, at the time of production of the whole cell pertussis vaccine, at Kasauli, as per the standard procedure recommended by WHO, three parallel batches of the pertussis culture were inactivated in fermenter before harvesting and thiomersal was used only one time for suspending the bacterial mass after harvesting. The resultant modified vaccine so prepared when tested showed that it was of better quality as compared to the one produced by standard procedure, when tested in mice.

Diagnosis of tuberculosis in an era of HIV pandemic: A review of current status and future prospects.

HIV and tuberculosis co-infection interact in fundamentally important ways. This interaction is evident patho-physiologically, clinically and epidemiologically. There are several differences between HIV-infected and HIV-uninfected patients with tuberculosis (TB) that have practical diagnostic implications. TB is more likely to be disseminated in nature and more difficult to diagnose by conventional diagnostic procedures as immunosuppression progresses. As TB rates continue to increase in HIV-endemic regions, improved diagnostic techniques merit consideration as TB-control strategies. There is a need to develop more user friendly techniques, which can be adapted for use in the high-burden and low-income countries. This review focuses on the diagnostic challenges in HIV-TB co-infection with an update on the current techniques and future prospects in an era of HIV pandemic.

Pediatric hospitalizations associated with 2009 pandemic influenza A (H1N1): An experience from a tertiary care center in north India.

Objectives To describe our experience in children hospitalized with the pandemic Influenza A (H1N1) from Northern India. Methods The retrospective case study was conducted at the Pediatric ward and Pediatric Intensive Care Unit (PICU) dedicated to the children (aged 18 years or younger) with influenza-like illness (ILI) with positive laboratory test results for pandemic H1N1 by reverse-transcriptase polymerasechain- reaction assay. Results Between August 2009 and January 2010, a total of 100 children were hospitalized with suspected 2009 H1N1 influenza with Category “C” as described by the Government of India. Twenty five patients were positive for H1N1 and 9 for seasonal influenza A. The most common presentation (H1N1 positive) was with fever (100%), cough (100%), coryza (52%), respiratory distress (88%), vomiting (28%) and diarrhea (16%). One child presented with hypernatremic dehydration and seizures (Serum sodium 174 meq/l). Of the H1N1 positive hospitalized children, 7 (28%) had respiratory failure and required PICU admission, 4 (16%) required mechanical ventilation, and 3 (12%) died. The major radiological findings were bilateral pulmonary infiltrates and consolidation. All patients were treated with oral Oseltamivir suspension or capsule as per appropriate weigh band and supportive care as required. Two deaths were caused by refractory hypoxemia and one by refractory shock. Conclusions The exact incidence of Pandemic 2009 H1N1 influenza on morbidity and mortality is difficult to calculate since only Category “C” patients were screened.

Respiratory Viruses in Acute Bronchiolitis in Delhi.

We studied the etiology of bronchiolitis in Delhi. Respiratory syncytial virus (RSV) was the most commonly isolated virus in 72/245 infants (30%). RSV positive cases did not have more severe disease; this argues against routine use of ribavirin.

Red baby syndrome a new disease due to parvovirus B-19 observed in Kerala.

Red Baby Syndrome is a new disease seen in infants and young children. Dramatic onset of clinical symptoms with high intensity, short duration and lack of similarity with other cutaneous lesions makes it distinct. Of 50 such patients studied over a period of 5 years, half were below one year of age. Abrupt onset of high fever and generalized erythema involving the entire skin, which is swollen and tender is characteristic. These children were highly irritable and had paradoxical cry when cuddled. Rapid resolution of symptoms occurred in 7-10 days with extensive desquamation. Routine investigations were normal, C-reactive protein was raised only in 10 patients. Human Parvo virus B-19 IgM antibodies were positive in 15 out of 24 patients. Real time polymerase chain reaction was positive for human parvovirus B 19 DNA in one. Histopathological changes in the skin biopsy showed post infectious vascular injury pattern.

A study of acute febrile encephalopathy with special reference to viral etiology.

OBJECTIVE: To study the etiological profile of patients with acute febrile encephalopathy syndrome focusing chiefly on the viral etiology, and to correlate clinical and radiological features of patients with viral encephalitis. METHODS: A prospective hospital based study conducted on the consecutive patients admitted in a pediatric unit during the period of 1(st) February 2004 to 31st January 2005 based on the following inclusion criteria: (1) Age more than 1 month and less than 18 years and (2) A diagnoses of acute febrile encephalopathy, based on the following criteria: (i) fever (ii) acute depression of consciousness or mental deterioration for more than 12 hours with or without motor or sensory deficit and (iii) Total duration of illness at the time of admission 1 week or less. RESULTS: The final study group comprised of 151 patients with mean age of 3.21 +/- 2.9 (range of mth-13 years) and male: female ratio of 1.71: 1. A diagnosis other than viral encephalitis was reached in 94 patients (62.3 %). Pyogenic meningitis was the most frequent diagnosis 51(33.8 %) followed by tubercular meningitis 12 (7.9 %), and cerebral malaria 8 (5.2 %) in the patient group of non-viral causes. Fifty-seven cases (37.3%) were suspected as viral encephalitis and mean age of the cases suspected as viral encephalitis was 2.8 +/- 2.9 (Range 1 mth-10 yrs) with male: female ratio of 1.28: 1. Etiological diagnosis was reached or considered probable in 41 (72%) cases out of the suspected patients. The most common etiological agent identified was enterovirus 71 in 20 patients (35.1 %). The other viruses identified were mumps in 6 (10.5%), Japanese encephalitis in 5 (8.7%), and measles in 4 (7%) cases. MRI brain was done in 39 patients and was abnormal in 14 patients. Out of 57 cases of suspected viral encephalitis 10 patients expired within 48 hours, 2 > 48 hours and 19 atients had significant neurological sequels at discharge. CONCLUSION: The etiology of acute febrile encephalopathy varies from infectious etiologies to noninfectious metabolic disorders. There are no distinguishing clinical or radiological features to differentiate the various causes of viral encephalitis. The clinical and the radiological findings in encephalitis should be interpreted in the geographical and other epidemiological background.

Detection of M. tuberculosis in clinical samples of diversified nature by IS6110 based PCR.

Performance of the polymerase chain reaction technique based on IS6110 sequence was evaluated in clinical samples obtained from pulmonary and extrapulmonary cases of tuberculosis. One hundred and seventy two samples were processed for detection of M. tuberculosis by ZN stained smear examination, LJ medium culture, BACTEC radiometric culture and PCR tests amplifying 123bp region of IS6110 sequence. A significant difference was seen in the sensitivities of different tests, the figures being 83% for PCR test, 35.2% for smear examination, 47.16% for LJ culture and 53.45% for BACTEC culture (p < 0.05). However, no significant difference was found as far as specificity was concerned. PCR test sensitivity in. pulmonary and extrapulmonary clinical samples were 90.14% and 77.27% respectively and found to be significantly higher (p < 0.05) when compared with those of other tests. The mean detection time for M. tuberculosis was 24.03 days by LJ medium culture, 12.89 days by BACTEC culture and less than one day by PCR test. PCR based on IS6100 sequence is highly sensitive method for the early diagnosis of pulmonary and extrapulmonary tuberculosis.

Congenital CMV infection in symptomatic infants in Delhi and surrounding areas.

Many viral infections are associated with significant maternal and fetal consequences during pregnancy among which cytomegalovirus is one of the most important agent, globally. Both primary and recurrent infection due to this virus can result in fetal infection. Samples from Congenital Anoammaled babies are referred to NICD from Delhi based Government hospitals and surrounding areas for diagnosis of congenital infections like Toxoplasm, Rubella, CMV and Herpes. In the present study, accumulated data is presented for the most common teratogenic virus--Cytomegalovirus prevalence as a causative agent for congenital infection in New Born babies at Delhi and surrounding areas. 96 samples from symptomatic babies in the age group of few days to 6 months exhibiting different congenital anomalies, were reported between 1 st Jan 04 to 30 th April/05. All the blood samples were tested for the detection of CMV (IgM) antibodies using m-capture ELISA technique. 18(18.75%) samples from babies showed positive titres for CMV-IgM antibodies. None of the mothers of positive babies were found positive for CMV-IgM antibodies but all were serologically exposed to CMV virus previously as their serum samples were positive for CMV-IgG antibodies indicating primary infection in the past or reactivation/reinfection with a different strain of CMV in the early pregnancy.

Molecular characterization of mutation associated with rifampicin and isoniazid resistance in Mycobacterium tuberculosis isolates.

Nucleotide changes in catalase peroxidase (Kat G) gene and gene encoding the beta subunit of RNA polymerase (rpo B), responsible for isoniazid and rifampicin drug resistance were determined in the clinical isolates of Mycobacterium tuberculosis by PCR-RFLP, Line probe assay and DNA sequencing. PCR-RFLP test was performed by HapII cleavage of an amplified fragment of Kat G gene to detect the transversion 315AGC-->ACC(Ser-->Thr) which is associated with INH drug resistance. The Line probe assay kit was evaluated to detect the mutation in 81bp RMP resistance determining region of rpo B gene associated with RMP drug resistance. These results were validated by DNA sequencing and drug susceptibility test. Kat G S 315 T mutation was found in 74.19% strains of M. tuberculosis from Delhi. This mutation was not found in any of the susceptible strains tested. The line probe assay kit and DNA sequencing identified 18 isolates as RMP resistant with specific mutation, while one of the RMP resistant strain was identified as RMP susceptible, with a concordance of 94.73% with the phenotypic drug susceptibility result. Majority (8 of 19, 42.1%) of resistant isolates involved base changes at codon 531 of rpo B gene. Both PCR-RFLP and Line probe assay test can be used in many of the clinical microbiology laboratories for early detection of isoniazid and rifampicin drug resistance in clinical isolates of M. tuberculosis.

Overview of avian influenza.

The current outbreak of H5N 1 avian influenza affecting an unprecedented number of countries is a cause of concern worldwide. As on 26th June, 2006 outbreaks in poultry or wild birds have been reported from 54 countries. In India the first outbreak of avian influenza virus Awas reported in Navapur district in Maharashtra in February 2006 followed by detection of H5N1 in a neighbouring district of Gujarat. No case of human infection has yet been reported in India. Avian influenza virus belongs to influenza type A which is a part of family orthomyxoviridae. Transmission occurs by direct or indirect contact. Clinical symptoms on human is of typical influenza like. Laboratory investigations involves a number of tests confirming diagnosis of avian influenza. The treatment includes general supportive and antiviral therapy with oseltamivir. Prevention and control strategies can held to minimise the public health risk to highly pathogenic avian influenza. There are some dos and don'ts for the community which should be strictly followed.

Protein antigen b (Pab) based PCR test in diagnosis of pulmonary and extra-pulmonary tuberculosis.

BACKGROUND AND OBJECTIVES: Diagnosis of tuberculosis (TB) is largely based on microscopy and culture examination which are either less sensitive, or time consuming. In the present study a PCR (polymerase chain reaction) test based on DNA sequence coding for a 38-kilodalton protein antigen b (Pab) ,specific for Mycobacterium tuberculosis was compared with Ziehl-Neelsen (ZN) stained AFB (acid fast bacilli) smear examination, culture based on conventional Lowenstein-Jensen (LJ) medium and radiometric BACTEC 460 system for the diagnosis of TB using clinical samples obtained from pulmonary and extra-pulmonary cases of TB. METHODS: Clinical samples obtained from 168 patients of suspected TB (pulmonary and extrapulmonary) were subjected to ZN smear examination, LJ culture, radiometric BACTEC culture and a PCR test by amplifying 419 bp sequence coding for Pab, a glycoprotein of molecular weight 38 kDa. RESULTS: A significant difference was seen in the sensitivity of different tests, the figures being 74.2 per cent for PCR test, 53.4 per cent for BACTEC culture, 47.1 per cent for LJ medium based culture and 35.2 per cent for ZN smear examination (P<0.05). However, there was no significant difference between different tests as far as specificity was concerned. PCR test sensitivity in pulmonary and extra-pulmonary clinical samples were 74.3 and 71.5 per cent respectively, being significantly higher (P<0.05) when compared with sensitivity of other tests. The mean detection time for M. tuberculosis was 24.0 days by LJ media culture, 12.8 days by BACTEC culture and less than 1 day by smear examination and PCR test. INTERPRETATION AND CONCLUSION: PCR test is more sensitive than ZN smear examination, LJ medium culture and BACTEC culture for diagnosing TB in pulmonary and extra-pulmonary clinical samples.

Comparative study of PCR, smear examination and culture for diagnosis of cutaneous tuberculosis.

Diagnosis of tuberculosis (TB), especially cutaneous TB by conventional laboratory method is unreliable and time consuming. We assessed the utility of Polymerase Chain Reaction (PCR) test vis a vis other laboratory tests in 37 clinical samples of skin biopsy from equal number of patients with different variants of cutaneous TB. The PCR test amplifying 165bp region of 65kDa antigen coding gene specific for M. tuberculosis was performed on skin biopsy samples obtained from cases with a strong clinical evidence of cutaneous TB. The samples were also subjected to other laboratory tests e.g. smear examination, conventional (LJ based culture) and rapid BACTEC culture and histopathological examination for mycobacteria. Significant difference (p<0.05) was observed in the sensitivity of PCR test vis-a-vis other tests e.g. smear examination, LJ and BACTEC culture. PCR test showed a higher sensitivity than histopathological examination but the difference was not found to be statistically significant (p>0.05). PCR test showed the maximum positivity of 79.4% followed by histopathology (73.5%), BACTEC culture (47.5%), LJ media culture (29.4%) and smear examination (5.8%). The sensitivity and specificity of PCR test employing culture as the "gold standard" were 95.2% and 100%. The mean time taken for a positive result in different tests were less than 24 hours for smear examination, 1 day for PCR test, 23.42 days for BACTEC culture and 38.02 days for LJ culture. These results show that PCR amplification of 165bp region of 65kDa antigen coding gene of M. tuberculosis is a rapid and sensitive test for diagnosis of cutaneous TB using skin biopsy samples.

Sensitivity index of antimicrobial agents as a simple solution for multidrug resistance in Salmonella Typhi.

BACKGROUND & OBJECTIVE: Multi drug-resistant (MDR) typhoid in India is an escalating problem. MDR isolates of Salmonella Typhi are on rise and are becoming a challenge for timely and appropriate treatment. Occurrence of per cent sensitive (%S), per cent resistant (%R) and per cent intermediate (%I) isolates may vary geographically and treatment decided on the basis of only one of these three subpopulations may lead to selection of inappropriate drug for treatment and thus treatment failure. Determination of sensitivity index (SI) of antimicrobial agents, instead of %S or %R subpopulations, may give clearer insight regarding selection of appropriate antimicrobial for treatment of typhoid. In present work, the data of sensitivity testing were analysed and interpreted both in terms of SI as well as %S, %I and %R. METHODS: A total of 205 isolates of Salmonella Typhi were collected during June 2000 and August 2002 from a network of five institutes- Lady Hardinge Medical College (LHMC, N=110), Ram Manohar Lohia Hospital (RML, N=14), Majeedia Hospital (MH, N=48), Lal's Pathology Lab (LAL, N=28) and All India Institute of Medical Sciences (AIIMS, N=5) on nutrient agar slopes. Of these, 142 isolates were subjected to phage typing and biotyping at National Salmonella Phage Typing Centre, New Delhi. Five isolates resistant to 3-7 and one isolate susceptible to all of total 12 antimicrobial tested were subjected to plasmid analysis. SI for various antimicrobials was determined as the ratio of %S and %R values derived form %RIS analysis using WHONET5. RESULTS: 18 (8.7%) isolates were susceptible to all tested antimicrobials and 124 (60%) were MDR. Of the 142 isolates, 103 were phage type E1 and biotype I. SI of antimicrobials rather than individual %S or %R or %I population presents a better criterion for interpretation of sensitivity testing data as well as selection of the most appropriate antimicrobial for timely treatment. Presence of 140, 48 and 23 Kb size plasmids in all 5 MDR isolates and none in susceptible isolate was observed. INTERPRETATION & CONCLUSION: Re-emergence of chloramphenicol sensitivity in Salmonella typhi was observed in the present study. Interpretation in terms of SI criteria warrants that reintroduction of chloramphenicol at present for treatment of typhoid may rebound resistance. Current empiric therapy used for treatment of typhoid may soon become ineffective. SI being a ratio will not only eliminate geographical variation of %RIS data but also its interpretation. SI can provide guidelines for clinicians in remote areas where facilities for sensitivity testing are not available.

Hand-foot-and-mouth disease in Calicut.

OBJECTIVE: Hand-Foot-and-Mouth Disease (HFMD) is a mild exanthematous illness seen worldwide, affecting mainly children under ten years of age. The causative agents were initially Coxsackie virus type A 16 and related serotypes. The situation changed drastically about thirty years ago with the advent of a new aetiological agent, Enterovirus type 71 (EV 71), which has caused very large outbreaks with severe complications and many deaths. METHODS: The authors report an outbreak of papulovesicular lesions on the skin and oral mucosa compatible with the diagnosis of HFMD in children in and around Calicut in October 2003. Clinical and laboratory study in collaboration with the National Institute of Communicable Diseases, Delhi. Eighty one children with the syndrome were examined and followed up from October 2003 to February 2004, when the outbreak subsided. RESULT: The outbreak was mild and all children recovered within 1 to 2 weeks. CONCLUSION: Acute and convalescent paired serum samples collected from 19 patients were examined at the NICD for IgM antibody against EV 71 by microneutralisation test in cell culture. All the paired samples tested showed significant rise in titre of antibodies, confirming the diagnosis of EV 71 infection in each of them.