P. Van der Auwera

Nosocomial bacteremia caused by Bacillus species.

During a six year period, 11 cases of bacteremia caused byBacillus spp. were observed corresponding to 1 % of all bacteremic episodes in our hospital. Most patients had cancer as underlying disease. All cases of positive blood cultures were associated with a clinical syndrome compatible with sepsis including high fever. None of the subsequent deaths could be related to the bacteremia caused byBacillus spp. Four of eight cases ofBacillus subtilis bacteremia were associated with the absorption of an oral preparation containingBacillus subtilis spores, which was administered empirically in some units of the hospital to reduce what was considered to be tubefeeding related diarrhea.

In vitro and in vivo intraleukocytic accumulation of azithromycin (CP-62, 993) and its influence on ex vivo leukocyte chemiluminescence.

The accumulation of azithromycin in phagocytic cells was studied both in vitro by using a radiolabelled drug and a bioassay and in vivo for 12 volunteers receiving 1.5 g (total dose) orally within 3 days. In vitro, neutrophils and unfractionated blood leukocytes accumulated azithromycin up to 160-fold the extracellular concentration within 1 h at 37 degrees C but less than 3-fold at 4 degrees C. Dead cells accumulated up to 30-fold azithromycin, whereas NaF-treated cells accumulated up to 60-fold arithromycin. The mean efflux from preloaded cells was at most 31.0% +/- 10.6% (standard error of the mean) of the cell-associated concentration within 4 h of incubation at 37 degrees C in drug-free buffer. In vivo, the azithromycin concentration was 45.2 +/- 6.1 mg/liter of intracellular fluid at 2 h after the third dose and 36.6 +/- 8.3 mg/liter at 1 week thereafter. The corresponding concentrations in serum were 0.2 +/- 0.1 (2 h) and less than 0.05 (1 week). The luminol-enhanced chemiluminescence response induced by phorbol myristate acetate, opsonized zymosan, and two opsonized strains of Haemophilus influenzae (a type b capsulated strain and a noncapsulated strain) was also studied ex vivo by using the blood leukocytes from the 12 test volunteers and 4 control volunteers at 2 and 6 h after the third oral dose of azithromycin and at 2, 4, and 7 days thereafter. Azithromycin did not influence this response despite high levels of cellular accumulation.

Marked increase of Pseudomonas aeruginosa serotype 012 in Belgium since 1982

Routine typing was performed on a total of 7089Pseudomonas aeruginosa strains isolated in 16 Belgian hospitals in the period from 1977 to 1986. The annual number of strains received ranged from 318 to 1346. The incidence of serotype O: 12 was less than 2 % until 1981 when it rose to 4 %, steadily increasing to become the predominant serotype in 1984 (22 %), 1985 (18 %) and 1986 (22 %). Since 1980 the O: 12 isolates have exhibited characteristic patterns on pyocin and phage typing, 89 % of O: 12 isolates belonging to pyocin types 1, 39, 43, 45 or 105, whereas only 51 % of isolates of other serotypes belonged to those pyocin types. Ninety-three per cent of serotype O: 12 isolates belonged to phage types 68/119x, 68 or 119x, or were non-typable, whereas only 24.37 % of other serotypes isolates exhibited these phage patterns. These distinctive patterns of pyocin and phage types suggest a high degree of homogeneity within the O: 12 strains isolated in recent years in Belgium. Multi-centre or country-wide survey ofPseudomonas aeruginosa strains isolated in hospitals using epidemiological markers may be of value in identifying a sudden increase in epidemic strains.

In vitro activities of new antimicrobial agents against multiresistant Staphylococcus aureus isolated from septicemic patients during a Belgian national survey from 1983 to 1985.

The antimicrobial agents most active against bacteremic isolates of oxacillin-resistant Staphylococcus aureus isolated from 1983 to 1985 were new fluoroquinolones, including PD 117,596 and PD 127,391 (MIC for 90% of isolates [MIC90] in agar, in micrograms per milliliter, 0.1) and temafloxacin, pefloxacin, and ofloxacin (MIC90, 0.4). Other active antimicrobial agents included fusidic acid (MIC90, 0.2) and fosfomycin (MIC90, 12.5). Vancomycin was active against all isolates. Mupirocin was very active (MIC90, 0.4).

Activity of intracellular antibiotics

SummaryWe have studied the intracellular bioactivity of several antimicrobial agents against two strains ofStaphylococcus aureus, a pathogen sequestrated in phagolysosomes, using peripheral blood neutrophils from human volunteers. This was compared to the activity of cell-associated drugs also measuredin vitro. Several discrepancies (high cellular association, low bioactivity) were observed (coumermycin, glycopeptides, erythromycin and clindamycin) which can be due to the binding of the drug to a particular cellular organelle, to intracellular metabolization or inactivation, to unfavourable conditions in the phagolysosome (pH drop), or to a toxic effect of the drug on the functions of the neutrophil. Addition of the antibiotic during ingestion was frequently associated with better neutrophil-dependent killing through several potential mechanisms: coingestion of the antibiotic with the inoculum, modification of opsonization, release of activating substances and fragilization of the microorganism to oxygen-dependent or -independent killing mechanisms.ZusammenfassungAn neutrophilen Granulozyten des peripheren Blutes von freiwilligen Probanden wurde die intrazelluläre Aktivität verschiedener Antibiotika gegen zwei Stämme vonStaphylococcus aureus, einem in die Phagolysosomen sequestrierten Erreger, untersucht. Dies wurde mit der Aktivität der zellassoziierten Substanz verglichen, die auchin vitro gemessen wurde. Es fanden sich Unterschiede wie hohe zelluläre Assoziation und geringe Bioaktivität bei Coumermycin, Glykopeptiden, Erythromycin und Clindamycin, die auf die Bindung der Substanz an bestimmte Zellorganellen, auf intrazellulärer Metabolisierung oder Inaktivierung, ungünstigen Bedingungen im Phagolysosom (Absinken des pH) oder toxischen Wirkungen der Substanz auf Granulozytenfunktionen beruhen könnte. Wenn das Antibiotikum während der Phagozytose zugegeben wurde, fand sich häufig eine Verstärkung der Abtötung durch Granulozyten, für die mehrere Mechanismen in Frage kommen: Phagozytose des Antibiotikums mit dem Inoculum, Modifizierung der Opsonisierung, Freisetzung aktivierender Substanzen, und Verstärkung der Anfälligkeit des Mikroorganismus gegenüber Sauerstoff-abhängigen oder-unabhängigen Inaktivierungsmechanismen.

Fatty acid composition ofStreptococcus milleri

The cellular fatty acids of 31 strains belonging to theStreptococcus milleri group were analysed by capillary gas-liquid chromatography. Results were compared with findings from biochemical differentiation of the strains intoStreptococcus constellatus (two strains),Streptococcus anginosus (16 strains) andStreptococcus intermedius (13 strains). Eight strains of various other streptococci were included as internal references, including three strains ofStreptococcus morbillorum, three strains ofβ-hemolytic streptococci, and two strains of enterococci. TheStreptococcus milleri strains formed a very homogeneous group according to fatty acid composition and were easily differentiated from other groups. However, within the group, it was not possible to differentiateStreptococcus constellatus, Streptococcus anginosus andStreptococcus intermedius by fatty acid composition alone.

Pneumococcal bacteremia in cancer patients

Twenty-eight episodes of Streptococcus pneumoniae bacteremia occurring in 27 cancer patients hospitalized in the Institut Jules Bordet between July 1979 and April 1985 were reviewed. Ten patients had hematological malignancies and 17 had solid tumors (in 7 cases, of the lung). Forty-four per cent of the patients were neutropenic (<1000/μl) and 36% of the patients were in septic shock. In 36% of the patients, no clinical source of S. pneumoniae bacteremia could be found. Seventy-nine (21% patients) received empirical antibiotic treatment containing a beta-lactam. Two patients who did not receive any empirical treatment died within 12 hours. Overall, 11/27 patients died within the first week, and 8/27 died within the first three days. Mortality in neutropenic patients was not different from that in non-neutropenic patients. In comparison with a similar study performed previously in our institution, there was no difference in incidence, type of patient, source of bacteremia, or mortality.

In vitro activity of enoxacin compared with norfloxacin and amikacin

The in vitro activity of enoxacin was tested against 1000 clinical isolates of gram-positive and gram-negative microorganisms and compared with that of norfloxacin and amikacin. The MIC90 of enoxacin was 1 mg/l forEnterobacteriaceae, 2.6 mg/l forPseudomonas aeruginosa and 6.2 mg/l forStaphylococcus aureus. The inoculum effect was minimal. The MlCs and MBCs forPseudomonas aeruginosa strains were significantly affected by the addition of calcium and magnesium ions. Synergy was occasionally observed between enoxacin and the antibiotics tested; antagonism was rare.

Moxalactam therapy of serious infections

SummaryTwenty-four patients were treated with moxalactam for 25 serious infections. Nineteen patients were septicemic and 18 presented severe underlying diseases considered to impair the normal response to bacterial pathogens. All of the pathogens had MICs of less than 12 mg/l except onePseudomonas aeruginosa strain with an MIC of 32 mg/l. The dosage ranged from 3 to 12 g/day; the route of administration was either i.v. or i.m. The duration of treatment was six to 26 days. Six patients had urinary tract infections (three bacteremia), four had pulmonary abscesses (two bacteremia), five had septic thrombophlebitis (five bacteremia) and ten had miscellaneous infections (nine bacteremia). Twenty-two (92%) patients responded favourably. Four patients (16.6%) developed superinfections due to organisms highly resistant to moxalactam: threeStreptococcus faecalis, oneBacteroides fragilis and oneAspergillus flavus. Tolerance was good. Nine moderate adverse reactions were observed: three cases of transient eosinophilia, two of phlebitis, three hepatic enzyme alterations and one rash. Moxalactam kinetics were measured in serum from 15 patients with normal renal function after receiving 1 g i.v. over 30 min. The mean peak level after the infusion was 82.8±12.1 (SE) mg/l; the mean trough level 8 h later was 6.2±1.7 (SE) mg/l. The serum half-life was 2.6±0.6 (SE) h for the β phase. Plasma clearance was 76.8±8.2 ml/min. Moxalactam was found to be highly effective in the therapy of life-threatening infections.Zusammenfassung24 Patienten mit 25 schweren Infektionen, darunter 19 Septikämien, wurden mit Moxalactam behandelt. Bei 18 Patienten war die natürliche Abwehr gegen bakterielle Pathogene infolge schwerer Grundkrankheiten vermutlich beeinträchtigt. Die minimalen Hemmkonzentrationen von Moxalactam für die pathogenen Erreger betrugen mit einer Ausnahme weniger als 12 mg/l; einPseudomonas aeruginosa-Stamm wies eine MHK von 32 mg/l auf. Moxalactam wurde i.v. oder i.m. in Tagesdosen von 3 g bis 12 g gegeben. Sechs der Patienten litten an Harnwegsinfektionen (drei mit Bakteriämie), vier an Lungenabszessen (zwei mit Bakteriämie), fünf an septischer Thrombophlebitis (alle mit Bakteriämie) und zehn an verschiedenen anderen Infektionen (neun mit Bakteriämie). Bei 22 Patienten (92%) wurde ein Therapieerfolg erzielt. Bei vier Patienten (16.6%) traten Superinfektionen durch gegenüber Moxalactam hochresistente Erreger auf. Isoliert wurden dreimalStreptococcus faecalis, je einmalBacteroides fragilis undAspergillus flavus. Moxalactam wurde gut vertragen. Nebenwirkungen mäßigen Grades traten bei neun Patienten auf, dreimal vorübergehende Eosinophilie, zweimal Phlebitis, dreimal Anstieg der Leberenzyme und einmal Exanthem. Untersuchungen zur Moxalactam-Serumkinetik bei 15 Patienten mit normaler Nierenfunktion nach Infusion von 1 g i.v. über 30 min ergaben mittlere Spitzenspiegel von 82,8±12,1 (SE) mg/l, acht Stunden später mittlere Talspiegel von 6,2±1,7 (SE) mg/l, eine Serumhalbwertszeit von 2,6±0,6 (SE) h in der Beta-Phase und eine Plasma-Clearance von 76,8±8,2 ml/min. Moxalactam erwies sich als hochwirksames Mittel zur Behandlung lebensbedrohlicher Infektionen.

Preincubation of Haemophilus influenzae with subinhibitory concentrations of macrolides: influence on human neutrophil chemiluminescence.

Preincubation of Haemophilus influenzae with antibiotics may influence opsonophagocytosis as studied by chemiluminescence. Two strains of H. influenzae (strain 1 [type b] and strain 2 [uncapsulated]) were pretreated with erythromycin, roxithromycin, clarithromycin, and azithromycin for 1 h in Haemophilus test medium (the last 25 min was either without serum or with 10% fresh serum or 10% decomplemented serum). Human neutrophils were stimulated with a pretreated or control inoculum at four different bacterium/neutrophil ratios and tested for luminol chemiluminescence with an LKB luminometer. The results were normalized for bacterium/neutrophil ratio and compared by the two-sided Wilcoxon test. Pretreatment of bacteria with one-half of the MICs of erythromycin, clarithromycin, and roxithromycin produced nonsignificant (P > 0.05) increases in the chemiluminescence response (means of 23% for strain 1 and 4% for strain 2). Pretreatment with azithromycin at one-half of the MIC produced an increase in the chemiluminescence response induced by serum-opsonized strain 1 (320% +/- 36% [mean +/- standard error of the mean]) and strain 2 (107% +/- 20%) (P < 0.05). This increase was concentration dependent: for strain 1, 60% +/- 18% at one-fourth of the MIC to 440% +/- 41% at the MIC; for strain 2, 10% +/- 5% at one-fourth of the MIC to 300% +/- 20% at the MIC. For strain 1, the maximal increase with azithromycin pretreatment (at the MIC) required opsonization with fresh serum. Opsonization with decomplemented serum was associated with a 53% +/- 21% increase; this increase was 28% +/- 3% in the absence of serum. For strain 2, azithromycin reduced the lag phase of the chemiluminescence response induced by the absence of serum but did not alter the chemiluminescence response in the presence of decomplemented serum. A significant contribution of soluble factors in the enhanced response observed with bacteria preincubated with azithromycin was excluded. The increase of the chemiluminescence response with azithromycin pretreatment was probably due to improvement in complement-dependent opsonization for strain 1 and to improvement in both serum-independent and serum-dependent opsonization for strain 2.