Role of molecular typing in an outbreak of Salmonella paratyphi A.

During the post monsoon season of 1996 an outbreak of human Salmonellosis caused by Salmonella serovar-paratyphi A occurred in New Delhi and had continued for over 2 months. A total of 36 clinically diagnosed enteric-fever cases were reported during this outbreak. The isolates were compared following their characterisation by biotyping, antibiogram-analysis, plasmid-profiling and IS200 probing, to study the relatedness in order to delineate a common source. The study included representative strains from both outbreak (15) and sporadic (7) cases for comparative analysis. Biotyping, antibiogram, whole cell protein-analysis and plasmid-profiling could not discriminate sporadic cases from outbreak strains, suggesting that a single clone/type (PT-1) may be prevalent in our region. In contrast, molecular-typing using IS200-probing revealed 2 clonally related strains circulating during the outbreak, as compared to the unrelated sporadic strains which exhibited considerable genetic diversity. Molecular analysis by IS200-probing, helped to assign an index case which provided a history of later outbreaks, since paratyphi A was repeatedly cultured in later outbreaks also. The study also suggests that genetic rearrangements can occur during the emergence of outbreaks. It reaffirmed the usefulness of IS200-probing in epidemiological investigations of Salmonella enterica serovars.

Mycoplasma pneumoniae and community-acquired pneumonia.

BACKGROUND: Community-acquired pneumonia is an important cause of mortality and hospitalization in all age groups. In temperate climates, Mycoplasma pneumoniae is a common respiratory pathogen causing pneumonia. Information on human Mycoplasma infection in India is scarce. METHODS: We aimed to determine the frequency of Mycoplasma pneumoniae infection among patients with community-acquired pneumonia in a prospective cross-sectional study. The assessment included clinical and radiological evaluation followed by microbiological evaluation for the specific pathogen. Microbiological investigations included aerobic and anaerobic blood culture, anti-Mycoplasma IgM antibody detection by gelatin particle agglutination test and ELISA, culture of respiratory tract secretions for Mycoplasma pneumoniae and other organisms, and detection of specific Mycoplasma pneumoniae antigen by indirect immunofluorescence. RESULTS: Sixty-two patients (42 men and 20 women; mean age 41.7 years) with community-acquired pneumonia were investigated prospectively. They included 42 immunocompetent and 20 immunocompromised patients. Six patients had definitive evidence of Mycoplasma pneumoniae infection and an additional 16 patients had a probable diagnosis. In all, 22 (35.5%) patients with pneumonia had Mycoplasma pneumoniae infection. Of these, 12 patients belonged to the immunocompromised group and 10 to the immunocompetent group. Patients with Mycoplasma pneumoniae infection also had secondary bacterial infection as evidenced by organisms isolated from blood in 50% and from respiratory tract secretions in 68%. CONCLUSION: Community-acquired pneumonia has a polymicrobial aetiology, of which the prevalence of Mycoplasma pneumoniae is 35%. The study has two implications: (i) Mycoplasma pneumoniae infection is frequently associated with secondary bacterial infection; and (ii) initial empirical antibiotic therapy for community-acquired pneumonia in India must include antibiotics with activity against Mycoplasma pneumoniae.

Anaerobic septicaemia by Fusobacterium necrophorum: Lemierre's syndrome.

Lemierre's syndrome is characterized by acute pharyngotonsillitis with secondary thrombophlebitis of the internal jugular vein which is complicated by multiple metastatic foci of infections. This syndrome is caused by Fusobacterium necrophorum in healthy young persons and is extremely rare in occurrence. A pre-school child with Lemierre's syndrome is reported. The diagnostic and therapeutic aspects are emphasized in order to sensitize physicians to this uncommon condition.