Dengue virus infection: Need for appropriate laboratory tests for diagnosis and management of the condition in children during an outbreak.

Background: Outbreaks of dengue infection occur in several parts of India with clockwork precision closely related to changing seasons. Most recent outbreak in Puducherry occurred between October 2012 and January 2013, affected a sizable pediatric population. A prospective study was done to characterize the demographic, diagnostic and clinical profi le of pediatric patients in a tertiary care center in Puducherry. Materials and Methods: Data of patients serologically positive for either dengue NS1 antigen or anti-dengue IgM antibodies were analyzed. Duration of fever, platelet count, complications, risk factors, morbidity and mortality were analyzed. Results: Among pediatric cases with fever who were screened for NS1/ IgM antibody during the recent outbreak, 161 (37.5%) tested positive. NS1 was detected in 85% while 5.5% tested positive for IgM and 3% for IgG. Few (4.9%) tested positive for both NS1 and IgM and 1.2% were positive for both NS1 and IgG. The mean age was 6 years of which 9% were <1-year, the youngest being 1-month old infant. Mean duration of fever was 4 days. Vomiting was associated in 42% of cases. Thrombocytopenia (51%) and hepatomegaly (41%) were two major observations. Among the NS1 positive cases, 49% had thrombocytopenia. IgM alone and NS1 with IgM were associated with thrombocytopenia in 67% and 78% respectively. 14 children had complications of dengue shock syndrome, and four had dengue hemorrhagic fever. Totally, 22 of the children had platelet transfusion. There was no mortality reported among any of these children. Conclusion: Combination of clinical fi ndings and rapid NS1, IgM detection helped in confi rming the diagnosis for appropriate management of dengue in children.

Multiple drug resistant carbapenemases producing Acinetobacter baumannii isolates harbours multiple R-plasmids.

Background & objectives: The nosocomial human pathogen Acinetobacter baumannii has high propensity to develop resistance to antimicrobials and to become multidrug resistant (MDR), consequently complicating the treatment. This study was carried out to investigate the presence of resistant plasmids (R-plasmids) among the clinical isolates of A. baumannii. In addition, the study was performed to check the presence of common β-lactamases encoding genes on these plasmids. Methods: A total of 55 clinical isolates of A. baumannii were included in the study and all were subjected to plasmid DNA isolation, followed by PCR to check the presence of resistance gene determinants such as blaOXA-23, blaOXA-51, blaOXA-58 and blaIMP-1 on these plasmids that encode for oxacillinase (OXA) and metallo-β-lactamase (MBL) type of carbapenemases. Plasmid curing experiments were carried out on selected isolates using ethidium bromide and acridine orange as curing agents and the antibiotic resistance profiles were evaluated before and after curing. Results: All the isolates were identified as A. baumannii by 16SrDNA amplification and sequencing. Plasmid DNA isolated from these isolates showed the occurrence of multiple plasmids with size ranging from 500bp to ≥ 25 kb. The percentage of blaOXA-51 and blaOXA-23 on plasmids were found to be 78 and 42 per cent, respectively and 20 isolates (36%) carried blaIMP-1 gene on plasmids. Significant difference was observed in the antibiograms of plasmid cured isolates when compared to their parental ones. The clinical isolates became susceptible to more than two antibiotic classes after curing of plasmids indicating plasmid borne resistance. Interpretation & conclusions: Our study determined the plasmid mediated resistance mechanisms and occurrence of different resistance genes on various plasmids isolated from MDR A. baumannii. The present findings showed the evidence for antibiotic resistance mediated through multiple plasmids in A. baumannii clinical isolates. This indicates towards a need for preventive measures to avert the dissemination of plasmid resistance determinants in clinical environments.

Contamination of community water sources by potentially pathogenic vibrios following sea water inundation.

Potentially pathogenic members of the Vibrionaceae family including Vibrio cholerae and Vibrio parahemolyticus were isolated from domestic sources of drinking water in coastal villages following sea water inundation during the tsunami in Southern India. Phenotypic and genotypic studies were done to confirm the identity and detection of toxins. Vibrio-gyr (gyrase B gene) was detected in all sixteen vibrio isolates. Toxin regulating genes i.e.: ctx gene, tdh gene, and trh gene, however were not detected in any of the strains, thereby ruling out presence of toxins which could endanger human life. Other potentially pathogenic bacteria Aeromonas and Plesiomonas were also isolated from hand pumps and wells, in a few localities. There was no immediate danger in the form of an outbreak or sporadic gastroenteritis at the time of the study. Timely chlorination and restoration of potable water supply to the flood affected population by governmental and nongovernmental agencies averted waterborne gastroenteritis. Assessment of quality of water and detection of potential virulent organisms is an important public health activity following natural disasters. This work highlights the importance of screening water sources for potentially pathogenic microorganisms after natural disasters to avert outbreaks of gastroenteritis and other infectious diseases.

Antimicrobial susceptibility patterns of Salmonella enterica serotype typhi in eastern Nepal.

The aim of the present study was to evaluate antimicrobial susceptibility patterns with special reference to multidrug resistance, susceptibility to ciprofloxacin, and bacteriophage typing of Salmonella enterica serotype Typhi isolated from blood sent for culture in a tertiary-care teaching hospital in eastern Nepal during January 2000-December 2004. In total, 132 strains of S. enterica Typhi, isolated from 2,568 blood culture samples collected from cases of suspected enteric fever, were tested for susceptibility to commonly-used antimicrobials by the disc-diffusion method. There were 35 multidrug-resistant strains. None of the isolates were resistant to ciprofloxacin. Of 52 isolates tested for minimum inhibitory concentration (MIC) of ciprofloxacin, 36 (69.23%) showed reduced susceptibility (MIC >0.25 mg/L). Of 112 strains tested for nalidixic acid susceptibility, 86 (76%) were resistant. Strains with reduced susceptibility to ciprofloxacin and resistance to nalidixic acid could be correlated. The commonest phage type was El. Nalidixic acid susceptibility could be a useful screening test for the detection of decreased susceptibility of S. Typhi to ciprofloxacin, a drug which is commonly used even for minor ailments in this area.

Detection of pneumolysin in cerebrospinal fluid for rapid diagnosis of Pneumococcal meningitis.

BACKGROUND & OBJECTIVES: Pneumolysin, a toxin produced by Streptococcus pneumoniae is associated with virulence and is found in all invasive isolates. Its role as a diagnostic tool has recently been exploited. Most of the methods used are based on molecular techniques and are not cost-effective. The present study was undertaken to evaluate a simple, rapid and cost-effective method to detect pneumolysin in CSF as a diagnostic test for pneumococcal meningitis. METHODS: A total of 75 CSF samples from children with presumptive diagnosis of acute pyogenic meningitis or encephalitis were subjected to Gram stain, culture and pneumolysin detection by Cowan 1 staphylococcal protein A co-agglutination technique. RESULTS: Pneumolysin was detected in 26(78.8%) of 33 culture proven CSF samples and 4(9.5%) of 42 culture negative samples. Antigen detection by Co-A had a specificity of 90 per cent and a sensitivity of 79 per cent when compared with culture. Compared to Gram stain, pneumolysin Co-A had a specificity and sensitivity of 91.0 and 92.0 per cent respectively. INTERPRETATION & CONCLUSION: Detection of pneumolysin was found to be a simple, low cost antigen detection assay for rapid diagnosis of pneumococcal meningitis, for routine use in the developing countries.

Melioidosis--a report from Pondicherry, South India.

Melioidosis is an acute infectious disease caused by a safety-pin-shaped gram-negative bacteria called Burkholderia pseudomallei. Here, we report the first case of melioidosis in a middle aged male agricultural worker, from Pondicherry. The isolation of this organism from subcutaneous nodules on the extensor aspect of his limbs underlines the diversity of its clinical presentation. Difficulty in identifying the organism which mimics any other non-fementing gram-negative bacilli (NFGNB) on cursory examination, highlights the importance of identification of NFGNB in endemic areas for specific treatment and prevention.

Problem of timely diagnosis in anthrax meningitis.

Anthrax continues to remain a problem in parts of India. Meningitis is often a complication encountered among cases with cutaneous anthrax. We have encountered a dozen cases of anthrax meningitis in our hosptal in the past decade. A sudden unexplained rise in cases in the past two years with hundred percent mortality stresses the need for rapid confirmatory diagnosis. Most of the cases admitted with central nervous system involvement had a provisional diagnosis of conditions other than anthrax meningitis. A strong clinical suspicion with a simple Gram stain smear of the CSF will help confirm anthrax meningitis in endemic areas.