Host defense abnormalities predisposing the patient to infection

In vitro assessment of phagocytosis: Interspecies comparison of chemiluminescence response

Phagocytosis is a major component of the host's defences against pathogens. Particulate or soluble stimuli trigger the intracellular respiratory burst in activated phagocytes which can be measured in vitro by the luminol-enhanced chemiluminescent response. In this study, the phagocytic capacity of peripheral blood leucocytes was assayed using chemiluminescence and preliminary in vitro activation by phorbol myristate acetate, opsonized zymosan or latex beads. Leucocytes from rats, mini-pigs, dogs, monkeys and humans were preincubated for 2 hr with either doxycycline (0, 2 and 50 mug/ml) (n = 5) or lead acetate (0, 2 and 20 mug/ml) (n = 5), both compounds impairing phagocytosis. Whatever the species and the activator used, a similar dose-dependent decrease in chemiluminescence response was observed with either doxycycline or lead acetate, showing that the results can be extrapolated between species and to humans. The chemiluminescence assay is proposed as a tool for assessment of the safety of drugs and chemicals.

Intracellular activity of both teicoplanin and vancomycin against Staphylococcus aureus in human neutrophils

The effects in vitro of both teicoplanin and vancomycin of blood peripheral human neutrophils have been studied by assays of antibiotic uptake and intracellular killing of previously phagocytosed Staphylococcus aureus. The effects of vancomycin and teicoplanin (a novel glycopeptide antibiotic), at the therapeutic concentrations reached in plasma (10, 25, 50, 75 and 100 mg/l) and at different times of incubation (5, 15, 30 and 60 min) were studied. The results indicate that: (1) the bactericidal effect of neutrophils increases with incubation time, (2) in the presence of both teicoplanin and vancomycin, the number of CFU/ml of intraphagocytic S. aureus declines with both increasing incubation time and exposure dose of the antibiotics and (3) at 100 mg/l of teicoplanin there is a significant increase in the percentage inhibition of S. aureus growth at all the times studied.

Candida and oral candidosis: a review

Candida species are the most common fungal pathogens isolated from the oral cavity. Their oral existence both as a commensal and an opportunist pathogen has intrigued clinicians and scientists for many decades, and recent investigations have revealed many attributes of this fungus contributing to its pathogenicity. In addition, the advent of the human immunodeficiency virus infection and AIDS has resulted in a resurgence of oral Candida infections. Clinicians are witnessing not only classic forms of the diseases but also newer clinical variants such as erythematous candidosis, rarely described hithertofore. Therefore, this review is an attempt at detailing the current knowledge on Candida and oral candidoses together with the newer therapeutic regimes employed in treating these mycoses.

Lethal infections in patients with hematological malignancies

The hospital files of 410 patients with hematological malignancy treated at our clinic between 1977 and 1990 were reviewed to determine the importance of infections as a cause of death. The total number of infections was 203 (49.5%). A microbiologically documented infection was detected in 27.3%, a clinically documented infection in 9.5% and a possible infection in 12.7% of the patients. Gram-positive bacteria were responsible for 25.9%, gram-negative bacteria for 31.3%, anaerobic bacteria for 2.7%, viruses for 4.5% and fungi for 25.9% of the microbiologically documented infections. Of 29 systemic fungal infections only 2 were diagnosed before the patients died. The remaining diagnoses rested on autopsy findings. Empiric antifungal therapy was introduced in 1983; still, 74.2% of systemic fungal infections in 1977-1990 were detected after 1982. Patients with a verified infection had statistically significantly higher CRP concentrations than patients who died of other causes (152 mg/l vs. 117.5 mg/l, p = 0.018). We conclude that infection is a significant cause of death in patients with these diseases. The number of systemic fungal infections is increasing, despite the widespread use of antifungal medication and thus better diagnostic methods and more effective treatment are needed.

Selective oral antimicrobial prophylaxis for the prevention of infection in acute leukaemia-ciprofloxacin versus co-trimoxazole plus colistin. The EORTC-Gnotobiotic Project Group

230 leukaemic patients were entered into a randomised, prospective, multicentre trial of either ciprofloxacin (1 g/day) or co-trimoxazole (1920 mg/day) plus colistin (800 mg/day) for the prevention of infection during granulocytopenia. Bacteraemia due to resistant gram-negative rods occurred only in the co-trimoxazole-colistin group though both regimens were effective for selective gastrointestinal tract decontamination. However, there were fewer patients without any infective complications (31% vs. 18%: P = 0.02), fewer febrile days [mean (S.D.) 5.9 (1.1) vs. 8.2 (1.4): P = 0.0242], a lower proportion of infective events (0.9 (0.16) vs. 1.2 (0.18): P = 0.005) and fever occurred later (median 19 vs. 14 days: 0.025 less than P less than 0.05) in the co-trimoxazole-colistin group. The choice of prophylactic regimen therefore appears to depend upon whether or not protection against gram-negative infection is required or better systemic prophylaxis overall.

Neutrophil functions in lead-exposed workers

Neutrophil functions were studied in 38 lead-exposed workers compared to 34 controls. Both groups were matched according to age, sex, drinking and smoking habits, ethnic origin and drug intake. Blood lead levels were found to be seven times higher in exposed workers than in controls. Phagocytosis assayed by chemiluminescence was found to be slightly but not significantly altered in exposed workers. In contrast, chemotaxis using the agarose technique was significantly depressed. These results are in agreement with previous in-vitro findings. A further assessment of clinical consequences is warranted.

Factors predisposing to oral yeast infections

The discussion of factors predisposing to oral yeast infections is very important, and we can ask: what is primary and what is secondary? Without predisposing factors it is difficult to have oral yeast infection, and a yeast infection may also be the first sign of a developing basic illness. As long as the predisposing factors cannot be eliminated, recurrences of oral yeast infections are to be expected. We can say that local and systemic factors permit this micro-organism to cause disease and that it is extremely rare to find a case of oral candidosis in which one or more of these factors cannot be identified. There are many kinds of lists in the textbooks and some review articles in the literature, but more research is needed for better understanding of factors predisposing to oral yeast infections.

Clinical implications of positive blood cultures

Positive blood cultures can be classified according to their veracity (true-positive or false-positive culture), clinical severity (inconsequential or life threatening), place of origin (community acquired or nosocomial), source (primary or secondary), duration (transient, intermittent, or continuous), pattern of occurrence (single episode, persistent, or recurrent), or intensity (high or low grade). In general, however, positive blood cultures identify a patient population at high risk of death. In my studies, patients with positive blood cultures were 12 times more likely to die during hospitalization than patients without positive blood cultures. Many bacteremias and fungemias occur in complicated clinical settings, and it appears that only about one-half of the deaths among affected patients are due directly to infection. Hence, it is appropriate to speak of "crude mortality" and "attributable mortality." Among hospitalized patients, recent trends include rising incidences of Staphylococcus aureus and coagulase-negative staphylococcal and enterococcal bacteremias and a dramatic increase in the incidence of fungemias. The diagnostic and therapeutic implications of blood cultures positive for specific microorganisms continue to evolve and are the subject of a large and growing medical literature.

Infectious complications in childhood acute leukemias

Infectious complications in children with acute leukemias are reviewed as to incidence, predisposing factors, microbiologic etiologies and treatment. Principles of antimicrobiologic therapy are presented for bacterial, fungal, viral, and protozoal infections seen in children with cancer. Prevention of infection is also discussed.

The effect of teicoplanin on leukocytic activity and intraleukocytic micro-organisms

The interference of teicoplanin with certain phagocyte activities was investigated in comparison with that of vancomycin. Neither teicoplanin nor vancomycin interfered with chemotaxis, adherence, phagocytosis or nitroblue tetrazolium reduction of human neutrophils. Teicoplanin, but not vancomycin, enhanced intracellular killing by neutrophils from normal donors and from a patient with chronic granulomatous disease. Human monocytes in the absence of fresh human serum did not significantly kill Staphylococcus aureus but when pre-treated with teicoplanin 90% of phagocytozed bacteria were killed during 4 h incubation.

Defective immunoregulation in children with chronic otitis media with effusion

Otitis media and middle ear effusions (MEE) are most common clinical problems in early childhood, for which an estimated one million tympanostomies are performed each year in the United States. Although many factors have been associated with MEE (age, sex, genetics, otitis media, socioeconomic status, feeding style, atopy or hypersensitivity, certain bacteria and viruses), a defective immunoregulatory mechanism in the host may also contribute to the pathogenesis. During the past 2 years, we have evaluated immune function in 90 randomly selected children who underwent repeated tympanostomy for persistent MEE. The T-cell subset ratio (OKT-4/OKT-8) was reduced (below 1.25) in 16%. In 33 children, generation of T-cell growth factor (IL-2) by peripheral blood lymphocytes (PBL) was evaluated and found to be decreased in 11. The mitogenic response of PBL to phytohemagglutinin (PHA) and pokeweed mitogen (PWM) stimulation was abnormal in almost half of the cases. Imbalance of T-cell subsets and decreased production of IL-2 indicate defective immunoregulatory function in some of these children, which may play a role in the pathogenesis of persistent MEE.