Haemophilus influenzae type b carriage and novel bacterial population structure among children in urban Kathmandu, Nepal.

Haemophilus influenzae type b (Hib) is a major cause of invasive bacterial infection in children that can be prevented by a vaccine, but there is still uncertainty about its relative importance in Asia. This study investigated the age-specific prevalence of Hib carriage and its molecular epidemiology in carriage and disease in Nepal. Oropharyngeal swabs were collected from children in Kathmandu, Nepal, from 3 different settings: a hospital outpatient department (OPD), schools, and children's homes. Hib was isolated using Hib antiserum agar plates, and serotyping was performed with latex agglutination. Hib isolates from children with invasive disease were obtained during active microbiological surveillance at Patan Hospital, Kathmandu, Nepal. Genotyping of disease and carriage isolates was undertaken using multilocus sequence typing (MLST). Swabs were taken from 2,195 children, including 1,311 children at an OPD, 647 children attending schools, and 237 children in homes. Overall, Hib was identified in 5.0% (110/2,195; 95% confidence interval [95% CI], 3.9% to 6.4%). MLST was performed on 108 Hib isolates from children carrying Hib isolates and 15 isolates from children with invasive disease. Thirty-one sequence types (STs) were identified, and 20 of these were novel STs. The most common ST isolates were sequence type 6 (ST6) and the novel ST722. There was marked heterogeneity among the STs from children with disease and children carrying Hib. STs identified from invasive infections were those commonly identified in carriage. This study provides evidence of Hib carriage among children in urban Nepal with genetically diverse strains prior to introduction of universal vaccination. The Hib carriage rate in Nepal was similar to the rates observed in other populations with documented high disease rates prior to vaccination, supporting implementation of Hib vaccine in Nepal in 2009.

Invasive pneumococcal disease: epidemiology in children and adults prior to implementation of the conjugate vaccine in the Oxfordshire region, England.

A 10-year invasive pneumococcal disease (IPD) enhanced surveillance project in the Oxfordshire region of the UK between 1996 and 2005 identified a total of 2691 Streptococcus pneumoniae isolates from all ages that provided a comprehensive description of pneumococcal epidemiology. All isolates were serotyped and those from children under 5 years of age were genotyped and a matched case-control study using adults hospitalized between 1995 and 2000 was performed to estimate the effectiveness of the pneumococcal polysaccharide vaccine in the local population. Fifty-one serotypes were isolated, with different age distributions. The overall incidence of IPD was 9.2 cases per 100 000 population per annum [95 % confidence interval (CI), 8.6-9.9] and that of meningitis was 0.7 per 100 000 population per annum (95 % CI 0.5-0.9). After adjusting for age, serotype 1 was found to be less likely to be associated with meningitis versus other IPD, compared with the most common serotype 14, whereas serotype 12F was more likely to cause meningitis than other IPD. There were significant temporal changes in IPD incidence of four serotypes, with decreases in serotypes 1, 12F and 14 and increases in serotype 8. A possible novel variant (from serotype 6A to 6B) was found using multilocus sequence typing analysis. From the matched case-control study of adults, the pneumococcal polysaccharide vaccine effectiveness was estimated to be 43 % (2-68 %), which did not change significantly after adjustment for pre-existing co-morbidities. The data provide a baseline against which the impact of the pneumococcal conjugate vaccine introduced in the UK in 2006 could be measured.

Farm animals as a putative reservoir for vancomycin-resistant enterococcal infection in man.

Using a highly selective enrichment broth, 62 isolates of vancomycin-resistant Enterococcus faecium were obtained from non-human sources; 35 isolates from raw sewage, 22 from farm animals and 5 from uncooked chickens. All strains possessed the Van A gene, conferring high-level resistance to vancomycin (MIC > or = 256 mg/L). Ribotyping of 42 of these isolates resulted in 14 distinguishable patterns. Two ribotyping patterns were found among isolates from animals and sewage and those from clinical sources. A blood and a urine isolate from separate hospital patients and porcine isolates shared the same ribotyping pattern number 6 and a stool isolate from a patient in the community and sewage isolates shared another pattern, number 10. This finding suggests that animals may serve as a reservoir of vancomycin-resistant enterococci (VRE), which may enter the human food chain. The emergence of VRE in hospital patients may reflect selection of these organisms in the hospital environment by antibiotic usage from which nosocomial spread might occur.

Faecal carriage and nosocomial spread of vancomycin-resistant Enterococcus faecium.

Eight clinical isolates of vancomycin-resistant Enterococcus faecium (VRE) were obtained from four renal and four other in-patients within an 11 week period during 1992. Characterisation of the isolates by restriction enzyme analysis with Sal I and rRNA gene restriction patterns (ribotyping) showed them to be clonally related. During the next 3 months an additional 14 VRE were isolated from hospital patients, nine of which were indistinguishable by ribotyping from the strain associated with the outbreak. An epidemiological survey was instigated in order to determine the level of carriage of this VRE. A total of 354 stool specimens was screened using a highly selective enrichment broth. VRE were detected in the stools of 11/73 (15%) of renal patients, 5/97 (5%) of other hospital patients and 3/184 (2%) of patients based in the community. Of the 25 stool isolates that were further characterised by ribotyping, 17 were indistinguishable from the outbreak strain. The remaining eight isolates gave seven different patterns. Patients harbouring the outbreak strain stayed in hospital significantly longer and had received more antibiotic treatment, for longer, than those patients from whom other VRE had been isolated. There was no significant difference in vancomycin or cephalosporin usage between the two groups of patients. Ribotyping showed there to be a number of clones of VRE carried by patients and that one of these clones was especially prevalent and has been responsible for the outbreak of infection in the renal unit. The technique also showed the presence of different VRE in general practice patients suggesting they are not just a hospital phenomenon.

The Fluoretec system for rapid diagnosis of bacteroides infections by direct immunofluorescence of clinical specimens.

Fluoretec, a commercial kit for the rapid diagnosis by immunofluorescence of infections caused by Bacteroides spp was compared with a standard culture method. A total of 1010 specimens were tested for the presence of B fragilis group by Fluoretec F and B melaninogenicus-oralis and asaccharolytic groups by Fluoretec M. Fluoretec F was positive in 123/152 specimens culturing B fragilis group strains. Seventeen specimens were positive by Fluoretec F but negative on culture. Fluoretec M was positive in 21 of 22 specimens from which B melaninogenicus was cultured. The Fluoretec system was convenient in use, results being obtained within one hour of receipt of the specimen.