Gunnar Hopen

PORPHYRIN‐INDUCED PHOTODAMAGE TO ISOLATED HUMAN NEUTROPHILS

Abstract— Human neutrophils were irradiated with light at 340–380 nm in the presence of low concentrations of protoporphyrin or uroporphyrin. At increasing light doses or increasing concentrations of protoporphyrin, the neutrophils rapidly lost the ability of locomotion. Also, neutrophil chemiluminescence and hexose‐monophosphate shunt activity rapidly declined. An early event was leakage of endogenous K+ followed by lactate dehydrogenase and at a later stage leakage of particle‐bound acid phosphatase. A number of cellular enzymes were inactivated, the susceptibility to inactivation decreased in the order: succinate dehydrogenase > lactate dehydrogenase > glutamate dehydrogenase > acid phosphatase. Uroporphyrin had no effect on neutrophil functions, leakage of K+, or cellular enzymes. The results suggest that photodamage to the plasma membrane and the mitochondria are earlier events than photodamage to lysosomes.

A multi-centre prospective study of febrile neutropenia in Norway: Microbiological findings and antimicrobial susceptibility

The urgent need to treat presumptive bacterial or fungal infections in neutropenic patients has meant that initial therapy is empiric and based on the pathogens most likely to be responsible, and drug resistance. The traditional empirical treatment in Norway has been penicillin G and an aminoglycoside, and this combination has been criticized over recent y. We wished to analyse the microbiological spectrum and susceptibility patterns of pathogens causing bacteraemia in febrile neutropenic patients. This was a prospective multicentre study. During the study period of 2 y, a total of 282 episodes of fever involving 243 neutropenic patients was observed. In 34% of episodes bacteraemia was documented. Overall, 40% of the episodes were caused by Gram-positive organisms, 41% by Gram-negative organisms and 19% were polymicrobial. The most frequently isolated bacteria were Escherichia coli (25.6%), α- and non-haemolytic streptococci (15.6%), coagulase-negative staphylococci (12.4%) and Klebsiella spp. (7.4%). None of the Gram-negative isolates was resistant to gentamicin, meropenem, ceftazidime or ciprofloxacin. Only 5 coagulase-negative staphylococci isolates were resistant to both penicillin G and aminoglycoside. The overall mortality rate was 7%, and 1.2% due to confirmed bacteraemic infection.

Ciprofloxacin versus a Tobramycin/Cefuroxime Combination in the Treatment of Serious Systemic Infections: A Prospective, Randomized and Controlled Study of Efficacy and Safety

Sequential intravenous and oral ciprofloxacin (CF) was compared with a combination of tobramycin and cefuroxime (T/C) in the treatment of serious systemic infections. Altogether 310 patients were randomized, 160 receiving CF and 150 T/C, the 2 groups being reasonably well balanced. 29 patients without infection were excluded from the analysis. Complete clinical resolution was obtained in 75% (107/143) patients receiving CF and in 78% (107/138) receiving T/C; the difference was not statistically significant. The rate of bacterial eradication in septicaemia was 72% (95% confidence interval (95% c.i.): 58-86%) for patients treated with CF and 87% (95% c.i.: 77-96%) when T/C was given, while the eradication rates in urinary tract infection were 72% (95% c.i.: 54-90%) and 45% (95% c.i.: 23-67%) for CF and T/C, respectively. Significant differences in bacteriological response for other diagnoses were not detected. Also for lower respiratory tract infections (LTRI) the clinical and bacteriological responses were quite similar, although relatively more failures occurred in CF treated patients with LRTI caused by pneumococci. The frequencies of adverse reactions were comparable, but the reactions were less serious following CF treatment. Our results indicate that CF may be used for empirical treatment of serious infections. However, if pneumococcal etiology is likely, alternative antibiotics should be used, and if necessary, coverage against anaerobic bacteria should be added.

Preventing Secondary Cases of Meningococcal Disease by Identifying and Eradicating Disease-Causing Strains in Close Contacts of Patients

In Norway, the use of chemoprophylaxis after cases of meningococcal disease is not recommended. Instead, household members less than 15 years are treated with penicillin for 7 days. Failures of this treatment have been reported. We therefore used DNA fingerprinting to identify the disease-causing strain in healthy contacts combined with selective rifampicin prophylaxis to these carriers to prevent secondary cases. During a 2-year period (1987-89) there were 13 cases of meningococcal disease in the County of Telemark (165000 inhabitants). 65 (14.7%) out of 441 contacts to these 13 patients harbored meningococci in their throat; 16 (3.6%) carried the disease-causing strain. Only 1 carrier fulfilled the criteria for being treated with penicillin; 8 were adults and the remaining 7 were not household members. No secondary cases of meningococcal disease occurred during the study period or the following 12 months. During the 4-year period (1984-87) preceding the study period there were 39 cases of meningococcal disease in Telemark; 7 of them were index cases for 12 bacteriologically verified and 4 clinically suspected secondary cases of meningococcal disease. We conclude that selective prophylaxis with rifampicin seems to be more efficient that penicillin treatment of household members less than 15 to prevent secondary cases of meningococcal disease.

Doxycycline induced photodamage to human neutrophils and tryptophan.

Abstract— Neutrophil functions were studied following irradiation (340–380 nm) of the cells in the presence of 22 mUM doxycycline. At increasing light fluence the locomotion, chemiluminescence and glucose oxidation (by the hexose monophosphate shunt) of the neutrophils steadily decreased. The photodamage increased with increasing preincubation temperature and time and was enhanced in D2O, reduced in azide and abolished in anaerobiosis. Superoxide dismutase, catalase or mannitol did not influence the photodamage. Photooxidation of tryptophan in the presence of doxycycline was increased9–10‐fold in D2O and nearly abolished in the presence of 0.25 mM NaN3, indicating that singlet oxygen is the most important reactive oxygen species in the doxycycline‐induced photodamage. The results may explain some of the features of tetracycline‐induced photosensitivity and why other authors have obtained diverging results when studying the influence of tetracyclines on neutrophil functions.

Effect of Doxycycline and PUVA Light on Human Polymorphonuclear Leukocyte Function

Polymorphonuclear leukocytes (PMNLs) are a cornerstone of host defense against infection, and the interaction of PMNLs with antimicrobial agents has been extensively studied [10, 14, 15]. Reports on the effect of tetracyclines on PMNL functions are contradictory. Chlortetracycline and doxycycline seem to markedly inhibit the phagocytic activity of the cells [5, 18] while no such effect has been demonstrated with tetracycline hydrochloride [9]. More recent reports [16, 17] have demonstrated only a slight decrease in phagocytosis of 32P-labeled Escherichia coli by human and rat PMNLs. Doxycycline administrated to healthy individuals has also been shown to slightly inhibit the migration to skin chambers [4].