An evaluation of dark field microscopy, culture and commercial serological kits in the diagnosis of leptospirosis.

CONTEXT: This study was conducted to analyze the clinical utility of various leptospira diagnostic modalities. AIMS: To evaluate the role of dark field microscopy (DFM), culture, immunochromatography (IgM Leptocheck), IgM enzyme-linked immunosorbent assay (IgM ELISA), macroscopic slide agglutination test (MSAT) and microscopic agglutination test (MAT) in diagnosing leptospirosis in febrile patients. SETTINGS AND DESIGN: Descriptive study conducted in a tertiary care hospital from January 2011 to April 2012. SUBJECTS AND METHODS: Blood, urine and paired sera from 100 patients with clinical suspicion of leptospirosis (study group) were collected and subjected to DFM, culture, IgM Leptocheck, IgM ELISA and MSAT. Fifty randomly selected sera from febrile patients tested positive for infections other than leptospirosis (control sera) were also subjected to the aforementioned serological assays. All the leptospira seropositive samples were subjected to MAT. STATISTICAL ANALYSIS USED: Positive predictive values (PPV) and coefficient of agreement (kappa). RESULTS: None of the clinical samples showed positivity by DFM. Leptospira inadai was isolated from a urine sample. The seropositivity of IgM Leptocheck, IgM ELISA and MSAT was 16%, 46% and 47%, respectively. The PPV of these assays was 14.3%, 8.7% and 6.5%, respectively. Poor agreement was obtained among these assays. Only four study group leptospira seropositive samples were confirmed by MAT with Australis being the predominant serovar. None of the leptospira-positive control sera were confirmed by MAT. CONCLUSIONS: DFM and culture have limited utility in diagnosing leptospirosis with serology being the mainstay. The present study shows discordant results with the commercially available serological kits. Further studies should be done to evaluate the various diagnostic modalities.

Profile of H1N1 infection in a tertiary care center.

BACKGROUND: A novel swine origin influenza virus (H1N1) is spreading worldwide and threatens to become pandemic.H1N1 critical illness mostly affects young patients and is often fatal. AIM: The aim of the present study is to evaluate the clinical characteristic of H1N1 infection in a tertiary care hospital. MATERIALS AND METHODS: A total of 92 nasal and pharyngeal swabs from suspected cases of swine flu were processed by real time reverse transcriptase polymerase chain reaction (rRT-PCR). RESULT: Twenty(21.73%) were positive of which two were treating physicians and five (25%) patients expired. CONCLUSIONS: The age group of positive cases of H1N1 was between 21 and 30 years and age group of patients who died ranged from 40 to 45 year. This overview indicates that although the majority of hospitalized persons infected with novel influenza A (H1N1) recovered without complications, certain patients had severe and prolonged disease. It was also noted that 2009 influenza A (H1N1) infection - related clinical illness predominantly affects young patients. All hospitalized patients with novel influenza A (H1N1) infection should be monitored carefully and treated with antiviral therapy. Mandatory vaccination of health-care workers is especially important in emerging pandemic.

Brucellosis: review on the recent trends in pathogenicity and laboratory diagnosis.

Brucellosis is a zoonotic infection transmitted from animals to humans by the ingestion of infected food products, direct contact with an infected animal or inhalation of aerosols. The last method is remarkably efficient given the relatively low concentration of organisms (10 - 100 bacteria) needed to establish infection in humans, and has brought renewed attention to this old disease. Brucella is a facultative intracellular pathogen that has the ability to survive and multiply in the phagocytes and cause abortion in cattle and undulant fever in humans. Brucella spp particularly B. melitensis, B. abortus, and B. suis represent a significant public health concern. At present, B. melitensis is the principle cause of human brucellosis in India. Molecular studies have demonstrated the phylogenetic affiliation of Brucella to Agrobacterium, Ochrobactrum, and Rhizobium. Human brucellosis still presents scientists and clinicians with several challenges, with regard to the understanding of its pathogenic mechanism, severity, progression, and development of improved treatment regimens. Molecular studies have now highlighted the pathogenesis of Brucella, for the development of newer diagnostic tools that will be useful in developing countries where brucellosis is a common, but often a neglected disease. This review compiles all these issues in general and the pathogenicity and newer diagnostic tools in particular.

Comparative study for the presence of enterococcal virulence factors gelatinase, hemolysin and biofilm among clinical and commensal isolates of enterococcus faecalis.

BACKGROUND: Biofilm production, gelatinase and hemolysin are the potential virulence factors of Enterococci. Gelatinase and hemolysin producing strains of Enterococcus Faecalis have been shown to cause severe infections in animal models. Biofilm production has been shown to enhance the persistence of E. faecalis in urinary bladder and other medical indwelling devices infections. AIMS: To compare the presence of gelatinase, hemolysin and biofilm formation among clinical and commensal isolates and to study the co-relation between virulence factors with respect to different clinical specimens. SETTINGS AND DESIGN: During the study period of 2 years from July 2004 to July 2006, 200 clinical isolates from nosocomial infections and 100 commensal isolates of E. faecalis were taken for the study. MATERIALS AND METHODS: The clinical and commensal isolates were tested for the presence of gelatinase, hemolysin and biofilm and compared. The presence of these virulence factors among different clinical isolates was also studied. STATISTICAL ANALYSIS: Chi-square and likelihood ratio analysis were carried out using SSPS version 5.1 software. RESULTS: The clinical isolates produced 39, 16.5 and 32.5% of gelatinase, hemolysin and biofilm, respectively, as compared to 31, 19 and 16% produced by the commensal isolates, respectively. Endotracheal tube infection, urinary tract infection, umbilical catheter tip infected isolates produced 60.8, 86.6 and 100% biofilm, respectively. CONCLUSION: Significant difference in the production of biofilm (P<0.001) was noted between clinical and commensal isolates. Organism isolated from medically indwelling devices produced high amount of biofilm, confirming its role in colonization and causing nosocomial infections.

Review of virulence factors of enterococcus: an emerging nosocomial pathogen.

Enterococcus, considered a normal commensal of intestinal tract, is fast emerging as a pathogen causing serious and life threatening hospital borne infections. This is attributed to acquisition of multi drug resistance and virulence factors of the organisms. The sequencing of Enterococcus faecalis has given a lot of insight into its genetic makeup. The E. faecalis strain V583, which has been sequenced, contains a total of 3182 open reading frames (ORFs) with 1760 of these showing similarity to known proteins and 221 of unknown functions. Strikingly unique to this genome is the fact that over 25% of the genome is made up of mobile and exogenously acquired DNA which includes a number of conjugative and composite transposons, a pathogenicity island, integrated plasmid genes and phage regions, and a high number of insertion sequence (IS) elements. This review addresses the genomic arrangement and the study of virulence factors that have occurred since the sequencing of the genome.