Browsing by Subject "Bacterial diseases"

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    Bacterial disease and antimicrobial susceptibility patterns in HIV-infected, hospitalized children: a retrospective cohort study
    (Public Library of Science, 2008) Jaspan, Heather B; Huang, Lyen C; Cotton, Mark F; Whitelaw, Andrew; Myer, Landon
    BACKGROUND: Serious bacterial infections are a major source of morbidity and mortality in HIV-infected children. The spectrum of disease is wide, and responsible organisms vary according to setting. The use of antibiotic prophylaxis and the emergence of multi-drug resistant bacteria necessitate examination of responsible organisms and their antibiotic susceptibility. METHODOLOGY/PRINCIPAL FINDINGS: A retrospective cohort study of all HIV-positive pediatric admissions at an urban public sector hospital in Cape Town between January 2002 and June 2006 was conducted. Children between the ages of one month and nine years with laboratory confirmed HIV status, serious bacterial infection, and a hospital length of stay of 5 days or more, were eligible for inclusion. Organisms isolated from blood, urine, and cerebral spinal fluid cultures and their antimicrobial susceptibility were examined, and compared according to timing of isolation to distinguish nosocomial versus community-acquired. One hundred and forty-one children were identified (median age 1.2 years), 39% of whom were on antiretrovirals started before or during this hospitalization. Bacterial infections involved all organ systems, however pneumonia was most common (67%). S. pneumoniae and S. aureus were the most common gram positive and K. pneumoniae was the most common gram negative organism. K pneumoniae isolates were resistant to many first and second line antibiotics, and were all considered nosocomial. All S. aureus isolates were methicillin resistant, some of which were community-acquired. Conclusions/Significance Bacterial infections are an important source of co-morbidity in HIV-infected children in resource-limited settings. Clinicians should have a low threshold to initiate antibiotics in children requiring hospitalization. Broad-spectrum antibiotics should be used judiciously. Clinicians caring for HIV-infected children should be cognizant of the most common organisms affecting such children, and of their local antimicrobial susceptibilities, when treating empirically for serious bacterial infections.
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    A study of biochemical and morphological aspects of macrophage function in experimental murine Nocardia asteroides and Nocardia brasiliensis infections
    (1987) Stephens, Janet; Folb, Peter I
    It is submitted in this thesis that the degree of activation or inhibition of macrophage function may differ in N. asteroides and N. brasiliensis infections with respect to release of plasminogen activator and of lysozyme The pattern of secretion of plasminogen activator and lysozyme in N. asteroides infections appears to differ in N. brasiliensis infection; and there is possibly a difference in the amount of lysozyme released by 2 day N. asteroides-activated macrophages and 2 day N. brasiliensis -activated macrophages. Strains of Nocardia organism did not influence macrophage morphology or ultrastructure. The study also shows the biochemical characteristics of plasminogen activator and lysozyme release, but not macrophage morphology and ultrastructure, are modified in the first 21 days of experimental Nocardia infections. There are three apparent mechanisms by which virulent strains of N. asteroides manage to survive within macrophages: (i) an ability to inhibit phagosome-lysozome fusion: (ii) alteration in the intraphagosomal pH: and (iii) alteration in the activity of the lysozomal enzyme acid-phosphatase. This study attempted to elucidate further the mechanisms enabling Nocardia organisms to persist and grow within macrophages. Reduced lysozyme release reflects diminished functional status of the macrophages of mice inoculated with N. asteroides or N. brasiliensis at certain times during infection. Reduced intracellular lysozyme levels have been linked with defects in bactericidal function. Such a reduction in intracellular and consequently extracellular levels of lysozyme might explain the capacity of Nocardia to survive intracellularly and to proliferate in the macrophage host.