No description available.

No description available.

No description available.

No description available.

No description available.

No description available.

No description available.

The project was concerned with the construction of defined attenuated derivatives of P. multocida serotype B:2 strains, causative agents of haemorrhagic septicaemia, and attempts were made to construct defined mutations in genes such as aroA, cya, and galE loci that have been used to induce attenuation in other bacterial strains. Mutants defective in the aroA gene were constructed by allelic exchange of the locus in the chromosome of the wild-type strains with a cloned aroA gene interrupted with a cassette encoding kanamycin resistance (KmR). The aroA defective strains were confirmed by PCR, Southern blotting, lack of growth on minimal medium and by enzyme assay. KmR inactivated aroA mutants JRMT1 and JRMT2 strains derived from P. multocida 85020 and Quetta strains, respectively, were highly attenuated in a mouse model, with an LD50 108 C.F.U./mouse after injection intraperitoneally (i.p.). In contrast, the wild-type strains had LD50 <50 C.F.U./mouse by this route. Vaccination once by the i.p. route or twice by the i.n. route with these aroA mutants gave complete protection to the mice against subsequent challenge i.p. with 10,000 LD50 of the homologous wild-type strain or 1000 LD50 of the heterologous wild-type strain. Vaccination with these by the s.c. route was not protective. When high doses of the attenuated strains were inoculated by the i.p. or i.n. routes, there was some spread to the internal organs but the organisms were cleared by 24 and 72 hrs respectively. In contrast, the wild-type parent strains spread rapidly and multiplied in high numbers and killed the mice by 24 and 96 hrs respectively.

Diss. (sammanfattning) Uppsala : Sveriges lantbruksuniv. / Härtill 5 uppsatser.

Neonatal septicaemia and nosocomial infection are major causes of morbidity in neonatal intensive care units (NICU) in both developed and developing countries. This study documents infective episodes at two resource disparate NICUs; the Grantley Stable Neonatal Unit (GSNU), Royal Brisbane and Women’s Hospital (RBWH), Australia 1997-2006 and Danang NICU, Vietnam. The specific aims are: 1. To compare the incidence of neonatal septicaemia at RBWH and Danang NICU. 2. To compare of the epidemiological characteristics of nosocomial infections in the two NICUs. 3. To study risk factors associated with nosocomial infection in the two NICUs (including staff numbers, infant numbers and nursing workload). 4. To review published guidelines on healthcare physical environments and staffing levels and to survey the GSNU & Danang NICU in relation to these. 5. To develop a prospective surveillance system to monitor infection episodes in Danang NICU 6. To recommend strategies for the control of neonatal sepsis in Danang NICU. The GSNU at the RBWH, Australia is a 71 bed neonatal care facility with an established infection surveillance system in a well resource environment. Danang NICU, Vietnam provides care to a high risk neonatal population with no established infection surveillance system in a developing country with more limited resources. This study found the GSNU had a low rate of neonatal septicaemia, during the ten year period from 1997 to 2006 with 253 babies (2.1%) diagnosed with septicaemia. In Danang NICU, in the year 2007 alone, there were 52 cases (2.9%) of septicaemia documented but the incidence of neonatal infection is likely to have underestimated due to (i) the failure to collect blood culture before commencing antibiotic treatment. (ii) Difficulties associated with data retrieval from maternal and neonatal records and (iii) lack of a systematic surveillance system with prospectively collected data. The organisms causing early onset and late onset septicaemia were substantially different in the two NICUs. Group B streptococcus (GBS) and Escherichia coli were the major organisms causing early onset sepsis (EOS) at the GSNU, accounting for 37.8% and 29.7% respectively, whilst coagulase-negative staphylococcus (CONS) was the commonest organism (25.7%) for late onset sepsis (LOS). In Danang NICU, Klebsiella spp was the major pathogen and was responsible for 75% of neonatal septicaemia in both early and late onset sepsis. The isolation of Klebsiella spp in a high proportion of infants at less than 48 hours may suggest nosocomial or maternal route of acquisition. The rate of GBS infections in Danang Hospital, Vietnam, is hard to estimate and interpret due to limited microbiologic data. The anti-serum used to classify the Streptococcal types is not readily available in Danang Hospital. In some cases, organisms that are isolated are suspected to be GBS however, this is not confirmed microbiologically. The study identifies a high prevalence of neonatal septicaemia in Danang NICU. It identifies a close relationship between rates of infection and poor nursing care practices and limited resources. The standard care system used at the GSNU as well as the international literature was studied in relation to infection control practices. This was then used to develop the following recommendations that specifically target a reduction in infection rates in Danang NICU: 1. Implement an infection surveillance system 2. Report regularly from the database and embed discussion of the data into unit management policy 3. Revise neonatal and pathology practice in relation to blood cultures 4. Use shorter duration of antibiotics course based on culture results 5. Modify care practices that expose infants to cross infection 6. Identify specific staff with particular responsibilities in maintenance of standards