Erythromycin treatment is beneficial for longstanding Moraxella catarrhalis associated cough in children

The benefits of antibiotic treatment and a nasopharyngeal culture in children with longstanding cough were analysed in a prospective randomized open study. Clinically suspected pertussis was excluded. Of 40 children given erythromycin for 7 days, 35 (88%) recovered in one week, compared with 17/47 (36%) untreated (p < 0.0001). Erythromycin eliminated Moraxella catarrhalis from the nasopharynx in 21/31 children (68%), compared with spontaneous disappearance in 7/35 (20%) untreated controls (p < 0.001). Purulent bronchitis or otitis media occurred in 2 children (5%) in the treatment group and in 21 (45%) in the control group (p < 0.01). To evaluate the clinical role of isolated pathogens, the 47 untreated subjects were studied. Seven of 35 children harbouring M. catarrhalis recovered, compared with 8/12 in whom this bacterium was absent (p < 0.01). No correlation was found between the isolation of Haemophilus influenzae or Streptococcus pneumoniae and the clinical outcome. Children with persistent cough > 10 days may benefit from erythromycin treatment. M. catarrhalis in the nasopharynx indicates prolonged symptoms and increased risk of bacterial complications.

A capsule-deficient mutant of Francisella tularensis LVS exhibits enhanced sensitivity to killing by serum but diminished sensitivity to killing by polymorphonuclear leukocytes

The live vaccine strain (LVS) of Francisella tularensis is killed by human polymorphonuclear leukocytes as a result of strictly oxygen-dependent mechanisms (S. Löfgren, A. Tärnvik, M. Thore, and J. Carlsson, Infect. Immun. 43:730-734, 1984). We now report that a capsule-deficient (Cap-) mutant of LVS survives in the leukocytes. In contrast to the encapsulated parent strain, the Cap- mutant was avirulent in mice and was susceptible to the bactericidal effect of nonimmune human serum. The mutant was killed by serum as a result of activation of the classical pathway of complement by naturally occurring immunoglobulin M. This killing by serum was mitigated by the presence of human polymorphonuclear leukocytes. After opsonization in complement component C5-deficient nonimmune serum, the Cap- mutant was ingested and survived in the leukocytes. Under these conditions, the parent strain was killed. The leukocytes responded to both the parent and the Cap- strain with a very low chemiluminescent response. Only the response to the parent strain was inhibited by superoxide dismutase. When the Cap- mutant was opsonized with immunoglobulin G, it induced a higher and superoxide dismutase-inhibitable chemiluminescent response and was killed by the leukocytes. In conclusion, the capsule of F. tularensis LVS seemed to protect this organism against the bactericidal effect of serum. When deprived of the capsule, the organism failed to induce an antimicrobial response in polymorphonuclear leukocytes and survived in the leukocytes. Survival in phagocytes is a key characteristic of intracellular parasites. The Cap- mutant of F. tularensis may become a useful tool in experiments to explain the differences between pathways of ingestion of intracellular parasites, evidenced by the death or survival of the parasite.

Single-dose pharmacokinetics of dicloxacillin in healthy subjects of young and old age

Dicloxacillin was administered as 2 g single intravenous doses to healthy young and old subjects of both sexes aged 19-32 years and 65-76 years, respectively, and the pharmacokinetics were studied. Peak serum concentrations were higher in young than in elderly subjects and in each age group in females than in males. The elimination rate was similar in all groups and the only striking pharmacokinetic differences observed were that the urinary recovery of active dicloxacillin was higher in young subjects and that the non-renal clearance was higher in elderly volunteers. The findings were interpreted to be due to a systemic metabolism of dicloxacillin, compensating for a reduced renal elimination in the elderly subjects. In all subjects dicloxacillin was well tolerated. No increases of serum creatinine were observed.

Long-lasting cell-mediated immunity induced by a live Francisella tularensis vaccine

The lymphocyte stimulation test was used to estimate specific cell-mediated immunity after vaccination with the live vaccine strain of Francisella tularensis. Nonvaccinated individuals and individuals vaccinated 1, 5 to 6, 7 to 8, and 9 years previously were tested. Lymphocytes from most vaccinees responded to an antigen preparation of the vaccine strain, and those vaccinated 9 years before testing responded to a similar extent as did vaccines in the other groups. A new technique was developed to study the presence of T lymphocytes among the stimulated cells. Stimulated cells were allowed to incorporate [14C]thymidine and were then fractionated into T and non-T lymphocytes. Most of the incorporation appeared in the fraction containing T lymphocytes. The data indicate that cell-mediated immunity endures for at least 9 years after vaccination with the live F. tularensis vaccine.

Anaerobic phagocytosis, killing, and degradation of Streptococcus pneumoniae by human peripheral blood leukocytes

Encapsulated Streptococcus pneumoniae of serotypes 2, 9N, 14, 21, and 23F and an unencapsulated variant of type 2 pneumococci were efficiently phagocytosed by both aerobically and anaerobically incubated human leukocytes. In the presence of O2, the pneumococci rapidly lost their viability, whereas during anaerobiosis, killing was considerably delayed. Type 14 pneumococci radiolabeled with [14C]choline or [14C]ethanolamine for cell wall teichoic acid, [14C]uracil for nucleic acids, or [14C]arachidonic acid for unsaturated cytoplasmic membrane lipids were used in studies of the fate of bacterial macromolecules after phagocytosis. The degradation of teichoic acid, RNA, and DNA during anaerobiosis approached that recorded in air at 60 min of incubation (45 to 70% and 55 to 75%, respectively). In contrast, the marked loss of [14C]arachidonic acid from pneumococcal membrane lipids observed in aerobic leukocytes did not occur during anaerobic incubation. Hence, lipid peroxidation could be involved in the rapid aerobic leukocyte killing of pneumococci, whereas a different leukocyte function of as yet unknown nature appears to be responsible for the killing seen in anaerobiosis. Autolysis-resistant type 14 pneumococci were obtained by substituting ethanolamine for choline in a defined culture medium. Differences between such bacteria and normal (autolytic) pneumococci in their killing and degradation by leukocytes were not detected in either the presence or the absence of O2. The aerobic and anaerobic handling of phagocytosed pneumococci by human blood leukocytes thus proceeded independently of the bacterial autolytic system.

Antigen from Francisella tularensis: nonidentity between determinants participating in cell-mediated and humoral reactions

After tularemia vaccinations, most individuals respond with cell-mediated and humoral immunity as disclosed by the lymphocyte stimulation test and enzyme-linked immunosorbent assay (ELISA), respectively. There is, however, no correlation between the magnitudes of the two responses, and some individuals show one of the responses only. We now report that the two responses are directed towards different antigenic determinants of the bacterium. Ether-water extraction of the live vaccine strain of Francisella tularensis gave a high yield of material reacting in ELISA as well as in the lymphocyte stimulation test. However, the specificity of the extract was low insofar as it reacted not only with lymphocytes and antibodies of tularemia-vaccinated individuals but also to a fairly high extent with those of nonvaccinated individuals. By using the extract as a starting material, a preparatory procedure was developed, resulting in antigen of high specificity in the two tests. The antigen prepared was a high-molecular-weight, carbohydrate-protein complex. Proteinase K treatment of the antigen abolished the lymphocyte-stimulating activity but did not decrease ELISA activity at all. Periodate treatment, on the other hand, greatly reduced ELISA activity but did not decrease the lymphocyte-stimulating activity. Thus, determinants of F. tularensis responsible for immunospecific lymphocyte stimulation seem to reside in protein, whereas ELISA activity seems to be due mostly to carbohydrate determinants.

A wild and an attenuated strain of Francisella tularensis differ in susceptibility to hypochlorous acid: a possible explanation of their different handling by polymorphonuclear leukocytes

We have previously reported that a wild strain of Francisella tularensis is much less efficiently killed by human polymorphonuclear leukocytes than is an attenuated strain. In the present study, the killing of the attenuated strain was found to be strictly oxygen dependent. The wild and the attenuated strains both induced a respiratory burst in the leukocytes. The difference between the strains in susceptibility to agents produced at the burst could be explained by a difference in susceptibility to hypochlorous acid.

Oxygen and serum complement in phagocytosis and killing of Propionibacterium acnes

Phagocytosis and killing of Propionibacterium acnes by human peripheral blood leukocytes were promoted by normal human serum and by serum depleted of immunoglobulin G and M. Serum that had been heat-inactivated, depleted of complement component C3, or depleted of C4 and factor B, did not promote phagocytosis or killing. Depletion of complement-component C4 or factor B from normal human serum did not impair its capacity to promote phagocytosis and killing of P. acnes. These results indicate that phagocytosis of P. acnes is mediated by complement component C3, activated either by the classical or by the alternative pathway. P. acnes was phagocytosed as efficiently under anaerobic as under aerobic conditions. The bacteria were, however, killed at a considerably slower rate by anaerobically incubated leukocytes than by leukocytes incubated in air. Thus, oxygen dependent mechanisms were essential for killing of P. acnes.

Phagocytosis and killing of Francisella tularensis by human polymorphonuclear leukocytes

Bacteria of a wild strain of Francisella tularensis were less efficiently killed by human polymorphonuclear leukocytes than were bacteria of an attenuated strain. This finding was explained to some extent by a less efficient phagocytosis, but bacteria of the wild strain also seemed to be more resistant to killing after ingestion.

Influence of complement on the chemiluminescent response of human leukocytes to immune complex

Vaccine bacteria of Francisella tularensis were mixed with human serum containing specific antibodies against the same organism, and the mixture was incubated at 37 degrees C for 30 min. The mixture induced a two-peak chemiluminescent response in polymorphonuclear leukocytes. The initial peak was induced by a soluble agent, formed during incubation. The formation of this agent involved the activation of complement component C5. The second peak of the chemiluminescent response was induced by the opsonized bacteria; this peak was augmented by complement component C3, whereas C5 had no influence.

Demonstration of opsonizing antibodies to Francisella tularensis by leukocyte chemiluminescence

Twenty-three individuals were vaccinated with a viable attenuated strain of Francisella tularensis, and blood was collected at various time intervals during 4 weeks. To demonstrate opsonizing antibodies, a mixture of serum and vaccine bacteria was incubated, whereafter the chemiluminescence response of polymorphonuclear (PMN) leukocytes to this mixture was recorded. No opsonizing antibodies against F. tularensis were found in sera obtained before vaccination. Eleven days after vaccination, sera from nine individuals, and 21 days after vaccination, sera from all 23 individuals contained antibodies. Antibodies were demonstrated earlier with the chemiluminescent technique that with the agglutination reaction. Heat treatment (56 degrees C, 30 min) or removal of complement component C3 from immune serum reduced the chemiluminescent response of the leukocytes. A high chemiluminescent response of the leukocytes was induced by immunoglobulin G (IgG)- and IgM-enriched fractions of immune serum in the presence of complement. In the absence of complement, the IgG fraction induced a low chemiluminescent response; the IgM fraction induced no response at all.

Time of lymphocyte response after onset of tularemia and after tularemia vaccination

Blood lymphocytes were prepared from 6 patients at various time intervals after the onset of tularemia and from 10 subjects after vaccination against this disease. Lymphocytes were also prepared from subjects who had been vaccinated 1 and 2 years previously. The lymphocytes were incubated in the presence of membranes of the vaccine strain. Lymphocytes obtained 2 weeks or later after onset of the disease responded to the membranes with increased deoxyribonucleic acid synthesis, whereas lymphocytes obtained earlier than 2 weeks after onset did not respond. Lymphocytes of the vaccinated subjects did not respond to the membranes of the vaccine strain before vaccination. Two to 4 weeks after vaccination lymphocytes from six of the vaccinees yielded a high response, and this response was consistently high for several months. Lymphocytes from four of the vaccinated individuals responded to a low extent only, and this was consistently low for several months. Lymphocytes from individuals vaccinated 1 year before testing responded to a similar extent to the membranes, as did lymphocytes from those who had been vaccinated 1 month previously. Lymphocytes from individuals vaccinated 2 years previously, however, showed a diminished response to the membranes. There was no correlation between titer of agglutinating antibodies and magnitude of lymphocyte reactivity.

Recurrent pneumonia and encephalitis due to Mycoplasma pneumoniae

Recurrent Mycoplasma pneumoniae encephalitis in a young man is reported. The patient appeared not to be immunodeficient and despite the presence of a focal inflammatory brain lesion with a predominance of polymorphonuclear cells no direct evidence of inent in M. pneumoniae respiratory tract infection still is unknown the case strongly indicates that certain individuals are somehow predisposed to such complications. The case also illustrates that CNS complications may occur even during a mild mycoplasma respiratory tract infection and that the radiological findings can mimic cerebral haemorrhage or abscess necessitating neurosurgical exploration.

Stimulation of human lymphocytes by a vaccine strain of Francisella tularensis

An immune response to Francisella tularensis was demonstrated in man by the lymphocyte stimulation test. Peripheral blood lymphocytes were obtained from 26 individuals vaccinated with a viable tularemia vaccine, from 29 unvaccinated individuals, and from two patients who had recently undergone tularemia. The lymphocytes were incubated in the presence of various dilutions of heat-killed bacteria of the vaccine strain. The bacteria induced a deoxyribonucleic acid synthesis in the lymphocytes from 18 of the vaccinated individuals and from the two patients which was higher than that in the lymphocytes from any of the unvaccinated individuals. The deoxyribonucleic acid synthesis was maximal after about 6 days of incubation irrespective of concentration of bacteria. Lymphocytes from vaccinated and unvaccinated individuals were stimulated by two unrelated agents, tuberculin purified protein derivative and pokeweed mitogen. Lymphocytes from the vaccinated individuals did not show a higher response to these agents than did those of the unvaccinated. This suggests that the lymphocyte response to the Francisella bacteria was not due to a nonspecific activation. The vaccine-induced lymphocyte stimulation did not correlate with serum antibodies agglutinating F. tularensis antigen.