Search

Resume Materiel et methodes Les concentrations minimales inhibitrices de nine antibiotiques ont ete determinees par une methode de reference (norme M11-A5 du National Committee for Clinical and Laboratory Standards) sur 376 souches de bacteries anaerobies strictes. Les souches se repartissaient ainsi : 254 Bacteroides du groupe fragilis (dont 143 B. fragilis ), 122 autres bacteries a Gram negatif ( Bacteroides spp. , Prevotella, Fusobacterium, Porphyromonas, Suterella, Desulfomonas, Veillonella ). Resultats Chez B. fragilis (groupe) les taux de resistance sont les suivants : amoxicilline–acide clavulanique 2,8 %, ticarcilline 27,5 %, ticarcilline–acide clavulanique 1,9 %, piperacilline–tazobactam 1,9 %, cefoxitine 6,2 %, imipeneme 0,8 %, clindamycine 28,3 %. Considerant les etudes multicentriques anterieures, la resistance a l’imipeneme reste faible en 2003 et n’est observee que chez B. fragilis . La resistance a la clindamycine se maintient et avoisine les 25 %. Aucune resistance au metronidazole n’est constatee, mais une sensibilite diminuee est observee chez B. fragilis , B. merdae et Prevotella , soit chez 4,3 % des anaerobies a Gram negatif. Discussion Cette etude confirme la forte resistance des anaerobies a Gram negatif a la clindamycine, les bonnes activites de l’imipeneme, des associations β-lactamines–inhibiteur de β-lactamase et du metronidazole. Cependant, la sensibilite diminuee au metronidazole semble augmenter.

Resume Des etudes taxonomiques recentes ont demontre l’heterogeneite de l’espece Burkholderia cepacia (ex Pseudomonas cepacia), et on parle desormais de complexe cepacia, constitue a ce jour de neuf especes. Il s’agit de bacilles a Gram negatif non fermentants, presents dans l’environnement naturel et se comportant comme des pathogenes opportunistes de l’homme. Les Burkholderia du complexe cepacia sont essentiellement responsables de colonisations pulmonaires dans la mucoviscidose, ou elles sont particulierement redoutees en raison de leur impact clinique defavorable et du potentiel epidemique de certaines souches. Leur prevalence actuelle dans la mucoviscidose en France est voisine de 3 %, avec une tres large predominance des especes B. cenocepacia et B. multivorans, representant respectivement 46 et 47 % des isolats francais. Ces bacteries sont episodiquement rapportees dans des infections nosocomiales en dehors de la mucoviscidose, survenant souvent sous forme de cas groupes a partir d’une source commune contaminee. Les options therapeutiques sont limitees en raison d’une resistance naturelle a la ticarcilline, aux aminoglycosides et a la colistine, et de frequentes resistances acquises. La piperacilline, la ceftazidime, le meropeneme (contrairement a l’imipeneme), et la temocilline sont les molecules les plus actives. Des synergies ont ete observees in vitro avec des associations doubles ou triples d’antibiotiques, mais aussi des antagonismes, et actuellement aucune association therapeutique n’est reellement validee en clinique. De nombreux travaux recents ont permis une meilleure comprehension de l’epidemiologie, de la physiopathologie et des mecanismes de resistance de ces pathogenes emergents, qui sont passes en revue dans cette synthese.

Resume Objectif. – Nous avons voulu evaluer la monotherapie par amoxicilline-acide clavulanique (AMC), aux posologies humaines, sur un modele de bacteriemie a E. coli secreteur de penicillinase de niveau intermediaire chez le microporc Yucatan. Methodes. – Nous avons developpe un modele experimental de bacteriemie chez 15 microporcs Yucatan : a j1h0, injection I.V. de 4,8 × 10 9 UFC d’ E. coli de phenotype intermediaire. Neuf d’entre eux ont ete traites par AMC (1g–0,1g, 3 × jour en intraveineux pendant une semaine). Cette dose correspond a 2–0,2 g chez l’homme, avec une pharmacocinetique comparable dans les 2 especes. Le traitement a ete debute 24 h apres l’injection de l’inoculum bacterien et poursuivi pendant 7 jours. A j5, les donnees des animaux traites ont ete comparees a celles des 6 non traites. Resultats. – Durant les 24 premieres heures, avant l’antibiotherapie, les microporcs ont presente un sepsis severe avec hemocultures positives (15/15), fievre (39,3 a j1h7 vs 37,9°C a j1h0), apathie, anorexie, leucopenie (2,3 × 10 3 a j1h1 vs 12,1 × 10 3 leucocytes/mm 3 a j1h0) suivie d’ hyperleucocytose (23,9 × 10 3 a j2 vs 12,1 × 10 3 leucocytes/mm 3 a j1h0) et thrombopenie (81 × 10 3 a j2 vs 325 × 10 3 plaquettes/mm 3 a j1h0). Dans le groupe non traite, 5 hemocultures sur 6 sont restees positives jusqu’a j5. Dans le groupe traite, 8 hemocultures sur 9 ont ete negatives a j5 avec une amelioration clinique rapide. Commentaires. – Le protocole therapeutique utilise est efficace dans notre modele, prefigurant une possible efficacite humaine.

Resume Le microbiologiste contribue a l’amelioration de la qualite de l’antibiotherapie en collaborant avec les cliniciens par une interface indispensable. Il doit agir par ses recommandations sur les indications precises des examens bacteriologiques ameliorant la qualite des prelevements, sur l’opportunite de leur realisation et aux bonnes conditions de leur transport. Le prelevement doit etre accompagne d’informations cliniques necessaires a la bonne orientation de l’analyse. Des procedures ecrites doivent constituer un guide. Les performances des actes bacteriologiques doivent etre ameliorees par des methodes rapides, certaines automatisables et par l’apport des moyens moleculaires de diagnostic comme l’amplification genique ou les bio-puces. L’antibiogramme apparaitra sous la forme de valeurs parametriques pour les infections graves, le rendu SIR etant suffisant dans les autres cas. Cet antibiogramme est l’objet d’une lecture interpretative. Completes par la notification des mecanismes enzymatiques de resistance, son compte rendu et son expression doivent etres clairs. Le microbiologiste peut induire la prise en consideration des parametres pharmacocinetiques et pharmacodynamiques en vue d’une optimisation de l’antibiotherapie. La mesure et la surveillance des concentrations seriques des antibiotiques deviennent comparables aux CMI et aux CMB. Une contribution sera apportee par l’etude des pouvoirs bactericides du serum dans les infections graves. En etudiant les actions synergiques en cinetique de bactericide des associations d’antibiotiques sur des souches resistantes, il mettra en evidence les meilleurs couples. Par la surveillance des resistances emergentes aux antibiotiques en indiquant la distribution des especes isolees, le taux de prevalence ou d’incidence et les caracteristiques des bacteries multiresistantes, il apporte sa contribution.

Objectives – Ceftriaxone is a semi-synthetic cephalosporin with a high level of protein binding to albumin. The authors wanted to determine whether the bound fraction was actively bactericidal. Material and method – The bactericidal activity of 3 ceftriaxone concentrations (5, 50, and 200 mg/L) in a brain-heart broth with and without human serum albumin, and in human serum, was evaluated by the time-kill technique on 3 S. pneumoniae strains with varying degree of susceptibility to penicillin G. Results – The low concentration (5 mg/L) exhibits a slightly better bactericidal activity on the penicillin G susceptible strain without albumin than with albumin, in the earlier contact phase. A similar bactericidal activity occurs in both media at the 6th hour and up to the late phase of bactericidal activity. Concerning the strains with an intermediate or total resistance to penicillin G, the bactericidal activity is identical in the three media. This implies that bound ceftriaxone has a bactericidal activity. Only the 5 mg/L concentration doesn't seem to exhibit any activity on the strain with decreased susceptibility. This may be explained by the existence of two binding-sites of ceftriaxone on serum albumin: a high-affinity, low-capacity site, and a low-affinity, high-capacity site. At low concentrations, only the high-affinity sites are bound and thus, the bound ceftriaxone is inactive. At high concentrations, the part of ceftriaxone mainly bound to the low-affinity sites is much more labile, and may thus interact with the PBPs having a higher affinity for ceftriaxone. Conclusion – This study demonstrates that bound ceftriaxone has a bactericidal activity against S. pneumoniae.

Objectives – Ceftriaxone is a semi-synthetic cephalosporin with a high level of protein binding to albumin. The authors wanted to determine whether the bound fraction was actively bactericidal. Material and method – The bactericidal activity of 3 ceftriaxone concentrations (5, 50, and 200 mg/L) in a brain-heart broth with and without human serum albumin, and in human serum, was evaluated by the time-kill technique on 3 S. pneumoniae strains with varying degree of susceptibility to penicillin G. Results – The low concentration (5 mg/L) exhibits a slightly better bactericidal activity on the penicillin G susceptible strain without albumin than with albumin, in the earlier contact phase. A similar bactericidal activity occurs in both media at the 6 th hour and up to the late phase of bactericidal activity. Concerning the strains with an intermediate or total resistance to penicillin G, the bactericidal activity is identical in the three media. This implies that bound ceftriaxone has a bactericidal activity. Only the 5 mg/L concentration doesn't seem to exhibit any activity on the strain with decreased susceptibility. This may be explained by the existence of two binding-sites of ceftriaxone on serum albumin: a high-affinity, low-capacity site, and a low-affinity, high-capacity site. At low concentrations, only the high-affinity sites are bound and thus, the bound ceftriaxone is inactive. At high concentrations, the part of ceftriaxone mainly bound to the low-affinity sites is much more labile, and may thus interact with the PBPs having a higher affinity for ceftriaxone. Conclusion – This study demonstrates that bound ceftriaxone has a bactericidal activity against S. pneumoniae.

Resume Objectifs De juillet 1997 a juin 1998, 15 laboratoires de microbiologie, organises en observatoire regional et repartis sur l'ensemble de l'Alsace, ont participe a un recrutement exhaustif des pneumocoques isoles en situation d'infection dans le but d'etudier leur sensibilite aux antibiotiques. Methode Les souches ont ete isolees de prelevements diagnostiques (prelevements pulmonaires, hemocultures, liquides cephalorachidiens, prelevements ORL). Resultats L'observatoire a recrute 599 souches dont 32,9 % sont des pneumocoques de sensibilite diminuee a la penicilline G (PSDP: concentrations minimales inhibitrices CMI > 0,06 mg/L). Parmi ces PSDP, dix souches presentent une resistance de haut niveau (CMI > 1 mg/L), trois sont resistantes a l'amoxicilline (CMI > 2 mg/L) et aucune au cefotaxime. La prevalence des PSDP est plus elevee chez l'enfant que chez l'adulte (45,3 % contre 28,2 %) et dans les pus d'oreille (59,4 %). Les PSDP sont frequemment resistants a l'erythromycine (76,6 %), au cotrimoxazole (65,2 %) et a la fosfomycine (18,4 %). Les serotypes 23, 14 et 9 sont les plus frequents: 29,1 %, 26,1 % et 17,9 % des souches respectivement. Conclusion Cette enquete a permis de preciser, pour la premiere fois, l'impact exact de la resistance de Streptococcus pneumoniae a la penicilline G et aux antibiotiques dans la region Alsace. La prevalence des PSDP est l'une des plus faibles observees en France la meme annee avec une proportion tres restreinte de souches resistantes a la penicilline G et aux autres β-lactamines, γ compris dans les pus d'oreille de l'enfant.

Resume En bacteriologie et virologie les techniques rapides doivent reduire le delai de reponse pour le clinicien et permettre l'instauration precoce d'un traitement adapte. Les systemes par culture faisant appel a de nouveaux substrats d'enzymes specifiques identifient les bacteries et detectent leur antibioresistance en quelques heures. Leurs performances sont dependantes de la richesse et de l'actualisation des banques de donnees. Les methodes de biologie moleculaire permettent l'identification de bacteries et de virus difficilement ou non cultivables (HCV) en deux a trois jours, ainsi que la detection de resistances aux agents antimicrobiens de Mycobacterium tuberculosis . La commercialisation de kits d'amplification genique ne doit pas faire oublier le controle de qualite ni les problemes de contamination et d'inhibiteurs. Les tests de detection d'antigenes peuvent apporter un resultat en 15 a 20 minutes. Leur realisation delocalisee necessite neanmoins un environnement adapte en raison des risques de contamination, ainsi qu'une reflexion quant a leur opportunite et leurs performances.

Resume La reussite des examens bacteriologiques pour la recherche des bacteries anaerobies strictes depend tres etroitement des conditions de prelevement et de leur transport. II est imperatif de les respecter afin de pouvoir apporter une documentation precise dans les infections ou ces bacteries sont impliquees. Les imperatifs generaux a respecter pour cette recherche sont: ne pas contaminer le prelevement par la flore endogene (peau et muqueuses hebergent naturellement des bacteries anaerobies) ; eviter tout contact avec l'oxygene qui engendre une mortalite rapide des anaerobies et par la suite, favorise l'emergence a la culture des bacteries aerobies associees. Les conditions particulieres pour les prelevements exigent que des dispositifs specifiques soient utilises: toute collection purulente doit etre ponctionnee a la seringue, en evitant les bulles d'air et les contaminations de surface, puis introduite dans un flacon adapte. L'utilisation de la seringue elle-meme comme vehicule n'est qu'une demarche par defaut. Lorsque le site infecte n'est pas ponctionnable il faut, apres une decontamination de surface, utiliser une curette pour obtenir un prelevement profond qui sera place dans un milieu de transport ou a defaut, prelever vigoureusement en profondeur avec un ecouvillon d'alginate de calcium, place ensuite dans un milieu de transport. Les prelevements solides issus de biopsies ou les pieces anatomiques peuvent etre deposees dans un tube sterile dispose dans un sachet plastique scelle contenant un melange reducteur ; le sang et les liquides internes peuvent etre injectes directement et transportes dans les flacons d'hemoculture anaerobie. L'acheminement des prelevements vers le laboratoire doit etre rapide et effectue a la temperature de 20 °C, la refrigeration a 4 °C etant nefaste. Un bon prelevement et des conditions de transport adaptes permettront une mise en evidence correcte des bacteries anaerobies strictes lorsque les cultures seront ensuite realisees selon un processus d'anaerobiose continue.

Resume L'objectif de l'etude etait de suivre l'evolution de la sensibilite a la ceftazidime, au cefotaxime, a l'imipeneme et a la ticarcilline, de souches bacteriennes appartenant a des especes porteuses de mecanismes de resistance acquise a ces antibiotiques: Klebsiella, Enterobacter, Serratia, Pseudomonas aeruginosa, Burkholderia (Pseudomonas) cepacia, Stenotrophomonas (Xanthomonas) maltophilia, Acinetobacter baumannii. De 1989 a 1993 (1994 pour P. aeruginosa), toutes les souches non repetitives appartenant a ces especes etaient recueillies le premier mois de chaque trimestre dans les laboratoires de bacteriologie de 12 CHU francais. La determination de la sensibilite aux antibiotiques etait realisee suivant la methode classique de diffusion en gelose et interpretee suivant les recommandations du Comite de l'Antibiogramme de la Societe Francaise de Microbiologie. Sept mille souches, en moyenne, ont ete annuellement etudiees. Ces souches ont ete isolees a partir de prelevements d'origine variee, en particulier a partir des urines et de prelevements respiratoires. Les activites in vitro de la ceftazidime et du cefotaxime sur les enterobacteries, exprimees en pourcentages de souches resistantes, sont demeurees relativement stables ces dernieres annees. Il est a noter que la frequence des souches de Klebsiella pneumoniae resistantes a la ceftazidime et au cefotaxime, apres avoir atteint un pic a 24 % en 1991, est retombee a 18 % en 1993. La frequence des souches resistantes a la ticarcilline chez Enterobacter cloacae et Serratia marcescens a egalement diminue. Quant a P. aeruginosa, la frequence des souches resistantes a la ceftazidime est demeuree a peu pres stable dans l'ensemble, de 7 % en 1989 a 8 % en 1994. Il en est de meme de la resistance a la ticarcilline (30–40 % de souches ticarcilline-R), tandis que la frequence des souches resistantes a l'imipeneme est passee de 12 % en 1989 a 18 % en 1994. Par ailleurs, concernant les phenotypes de resistance, alors que la frequence des souches sensibles a ces trois antibiotiques reste stable (≈ 60 %), on observe parallelement une augmentation de la frequence de la resistance isolee a l'imipeneme, passant de 4,6 % en 1992 a 8,1 % en 1994 et une diminution de la resistance isolee a la ticarcilline (16,3 % en 1994). Pour A. baumannii, la frequence de la resistance a la ceftazidime et au cefotaxime a augmente, celle a la ticarcilline a diminue et celle a l'imipeneme est demeuree stable, inferieure a 1 %. Pour les autres especes bacteriennes, l'activite de la ceftazidime est demeuree stable sur B. cepacia : 2 a 10 % de souches resistantes, sur K. oxytoca : 1 a 3 % et sur S. maltophilia : 70 a 80 %. L'interet de la surveillance reguliere de la sensibilite des principales especes bacteriennes pathogenes aux antibiotiques est de donner des bases objectives a l'antibiotherapie probabiliste et de permettre une bonne economie de l'antibiotherapie. Celle-ci sera facilitee par l'etude de la nature et de l'evolution des mecanismes de resistance en cause.

A 33 basepair oligonucleotide probe, designed from the sequence of the Clostridium difficile toxin B gene, was evaluated for its ability to detect toxigenic Clostridium difficile directly in stool samples, without culture or DNA isolation. Two different labelling techniques were investigated: radiolabelling and digoxigenin-labelling. One hundred ninety-six stools were tested, with a good correlation (96%) obtained between the oligonucleotide probe and the gold standard, the cytotoxicity tissue culture assay. The sensitivity and specificity were 83% and 100%, respectively. In parallel, a new commercially available enzyme immunoassay for the detection of Clostridium difficile toxin A in stool specimens was investigated. In 162 samples tested, a sensitivity of 80% and a specificity of 98% were obtained.

Toxin B from Clostridium difficile is cytopathic in vitro for various types of cells, including polymorphonuclear cells, lymphocytes, and monocytes. Since intestine lamina propria is rich in macrophages, we studied the effect of toxin B on human monocytes and on human macrophages generated in vitro by long-term culture of purified circulating blood monocytes. Upon addition of toxin B, human monocytes exhibited few modifications whereas macrophages adopted a stellate morphology, with rounding up of the perikaryon. Toxin B made microfilaments of actin disappear and induced an important reorganization of vimentin and a redistribution of tubulin. Membrane area increased by approximately 16%. Toxin B did not affect the viability of human mononuclear phagocytes and did not exert any significant lytic effect. It profoundly altered the phagocytic function of macrophages. When activated by gamma interferon in the presence of toxin B, monocytes were more cytotoxic for U-937 target cells than control monocytes activated in absence of toxin. Finally, the combined treatment of monocytes with gamma interferon and toxin B increased significantly the secretion of tumor necrosis factor alpha, whereas toxin B alone was unable to induce tumor necrosis factor production. These results suggest that morphological and functional alterations induced in human mononuclear phagocytes by toxin B from C. difficile are due to the disorganization of the cytoskeleton and the resulting impairment of the membrane traffic equilibrium.

Ofloxacin penetration into heart tissue (valve and myocardium), mediastinal fat, and sternal bone marrow was the object of a prospective nonrandomized study. Thirty-six patients undergoing mitral and/or aortic valve replacement were included. Patients were divided into two groups of 18 patients each. Group 1 patients were administered a single 400-mg intravenous dose of ofloxacin over a 30-min period upon anesthesia (n = 6) or at 1 h (n = 6) or 6 h (n = 6) prior to surgery. Group 2 patients received a 200-mg oral dose of ofloxacin every 12 h during the 48 h preceding surgery. In this group, the final dose of ofloxacin was administered 3 h (n = 9) or 8 h (n = 9) before anesthesia. Plasma and tissue ofloxacin concentrations were assayed by high-pressure liquid chromatography. In group 1 patients, the peak level in plasma was 15.9 +/- 2.5 micrograms/ml. Peak ofloxacin levels in tissue were reached by hour 1 and were 8.89 +/- 2.16 micrograms/g in myocardium and 5 +/- 0.75 micrograms/g in heart valves. A significant decrease in ofloxacin levels in heart valve tissue and sternal bone marrow was observed after hour 3. Nevertheless, ofloxacin myocardial, heart valve, and sternal bone marrow levels remained higher than the MICs for the usually susceptible pathogens for at least 3 h. In group 2 patients, myocardial levels were long lasting (6.46 +/- 1.92 micrograms/g [4 to 8 h] and 5.92 +/- 0.95 micrograms/g [8 to 12 h]) and remained higher than those observed in the other tissues over the entire study period. A progressive but insignificant decrease in ofloxacin heart valve levels was observed (from 2.46 +/- 0.40 micrograms/g [4 to 8 h] to 1.57 +/- 0.22 micrograms/g [8 to 12 h]). In both groups, concentration in mediastinal fat were lower and tended to decrease with time. These were 1.83 +/- 0.61 micrograms/g with the first hour and 0.85 +/- 0.43 micrograms/g between hours 8 and 12 in group 1 and 1.74 +/- 0.52 micrograms/g between hours 4 and 8 and 0.67 +/- 0.11 micrograms/g between hours 8 and 12 in group 2. In conclusion, satisfactory diffusion of ofloxacin into heart tissue seems to favor use of the drug in the treatment of bacterial endocarditis due to susceptible pathogens. Furthermore, the progressively decreasing concentrations observed in heart valve and sternal bone marrow and the poor levels achieved in mediastinal fat suggest the need for renewing injection 3 h following initial infusion if the drug is used as an antibiotic prophylactic agent during cardiovascular surgery.

Resume La reaction d'hybridation entre molecules d'acides nucleiques represente le fondement de l'utilisation de sondes d'ADN pour l'identification ou la detection de bacteries. Cette methode a l'avantage de permettre le diagnostic de bacteries difficiles a identifier par les methodes traditionnelles, toutefois ces bacteries doivent au prealable avoir ete cultivees sur milieux bacteriologiques. Elle permet egalement de detecter des genes codant des facteurs de virulence particuliers produits par certaines bacteries. Enfin, elle permet theoriquement de reperer des bacteries directement dans un produit pathologique, sans avoir a passer par l'etape de la culture classique. Malheureusement, cette methode etant tres specifique, elle ne permet de rechercher ou d'identifier que les especes pour lesquelles le biologiste possede des sondes. De plus, cette technique ne permet pas de determiner la sensibilite d'une bacterie a tous les antibiotiques. C'est pourquoi, a moins de rechercher specifiquement un germe defini dans un prelevement, cette methode ne dispense pas de la culture classique. Beaucoup de trousses diagnostiques actuelles utilisent des radioelements (125I), ont un prix de revient encore eleve et ont encore une sensibilite inferieure a celle de la culture lorsqu'il s'agit d'identifier une bacterie directement dans un produit biologique. On espere realiser des progres grâce aux techniques d'amplification de genes qui permettront d'augmenter la sensibilite de la methode.

The automated MagNA Pure DNA extraction method for Chlamydia trachomatis was compared with the manual Cobas Amplicor protocol using 100 µL of input sample volume from 964 specimens. Agreement between protocols was 96.1%. The automated extraction method had a sensitivity of 99% and a specificity of 100%. Amplification inhibition observed after manual preparation of samples (3.8%) was not apparent following automated extraction. Using 200 µL of sample in the automated extraction process lowered the detection limit without raising the inhibition rate. Furthermore, the automated extraction method halved the hands-on time required for the procedure.

Staphylococcus aureus bacteraemia (SAB) may be complicated by secondary metastatic infection such as endocarditis, osteomyelitis or septic arthritis. This cohort study aimed to assess the prognostic value of sustained bacteraemia for outcomes related to Staphylococcus aureus bacteraemia.The study took place in three tertiary-care, university-affiliated hospitals. Patients were prospectively included if they agreed to participate and if the following data were available: (a). surveillance blood culture taken between 24 and 48 h after commencement of effective antibiotic therapy; (b). appropriate investigations (at least a TTE) performed as suggested by the infectious diseases consult service. Patients with sustained bacteraemia defined as persistent positive blood cultures more than 24 h after commencement of effective antibiotic therapy were compared to patients for whom the surveillance blood culture was negative.One hundred and four patients were enrolled, including 51 patients diagnosed with sustained bacteraemia. Sustained bacteraemia was significantly associated with a higher frequency of secondary metastatic infection (p0.001) and with a higher frequency of CRP100 mg/l. Frequency of acute complications due to infection, septic shock and death due to bacteraemia was higher for patients with sustained bacteraemia but this difference was not statistically significant. Using a Cox model, the risk for death associated with sustained SAB, controlling for Index of comorbidity and age (categorised asoror=70 years), was 1.2 (95% CI: (0.5, 3); p0.05).In conclusion, surveillance blood cultures, especially performed on effective antibiotic therapy, may be a simple and cost-effective way to select a population at risk for secondary metastatic infection from SAB.

Objective The purpose of this study was to investigate and characterize in vitro the post-β-lactamase inhibitor effect (PLIE) of clavulanic acid against two β-lactamase-producing species of bacteria. Methods The PLIE was investigated against one strain of Klebsiella pneumoniae and one strain of Haemophilus influenzae. A stationary-phase inoculum of about 10 7 colony-forming units per mL of each bacterium was pre-exposed for 2 h to clavulanic acid, either alone or in combination with amoxicillin at various concentrations. After pre-exposure, the dilution required to remove the β-lactamase inhibitor was 1:100 or 1:1000 according to the bacterial species and their susceptibilities to clavulanic acid. Bacteria were counted hourly after drug removal, on solid agar medium. Results Control cultures exposed to amoxicillin alone after dilution, showed a delay in growth, which may be inherent to the time required to synthesize sufficient β-lactamase after the dilution steps. Control experiments clearly distinguished the post-antibiotic effect and the growth delay from the PLIE. Conclusion The PLIE could be one of several factors explaining why β-lactam/β-lactamase inhibitor combinations remain effective throughout the dosing interval, even if a few hours after in vivo administration, serum concentrations of β-lactamase inhibitor fall below levels that are active in vitro.

The in vitro activity of fusidic acid was evaluated against 242 strains of streptococci isolated from skin and soft tissue infections during a prospective multicentre study. Nearly 90% of strains were isolated from dermatology, emergency and medicine units. Groups A, B, C and G streptococci represented, respectively, 41.9, 20.6, 4.4 and 27.8% of the strains. The activity of fusidic acid was dependent on the media used. MICs were generally one dilution lower with heart infusion agar than with Mueller-Hinton agar supplemented with 5% horse blood (MIC(90) for the whole streptococcal population = 8 mg/L and 16 mg/L, respectively). The distribution of MICs was unimodal and only two strains displayed MICs of fusidic acid >/= 64 mg/L. In both media, fusidic acid was moderately active against streptococci. However, antibiotic concentrations obtained in the skin exceed the MIC(90) of fusidic acid for streptococci, possibly explaining its clinical efficacy in the treatment of common cutaneous infections.

Thirty-eight nontoxigenic strains of Corynebacterium diphtheriae isolated between 1987 and 1992 from clinical specimens of French patients were typed by biotyping, antibiograms, bacteriophage typing, ribotyping, and restriction analysis by pulsed-field gel electrophoresis (PFGE). Excellent correlation occurred between the genotypes defined by PFGE SfiI profiles or by ribotype BstEII profiles. Genotyping revealed seven genotype patterns among the 26 biotype mitis isolates, five among the nine biotype gravis isolates, and three among the three biotype belfanti isolates. Phage typing was nonreactive for nine of the 38 isolates. A combination of all the typing methods led to the identification of 19 different types of Corynebacterium diphtheriae.

Extended-spectrum beta-lactamases (ESBLs) are found in numerous Enterobacteriaceae, mainly in Klebsiella pneumoniae. We investigated the pharmacodynamics of two new extended-spectrum cephalosporins, cefepime and cefpirome, alone and combined with either amikacin or gentamicin or ciprofloxacin by means of time-kill curves against ESBL-producing, aminoglycoside-resistant K. pneumoniae. When used alone, cefepime (8 and 16 mg/l) resulted in a 2 and 3 log decrease at 6 h, respectively, but at 24 h regrowth occurred. The combination of cefepime (8 mg/l) with amikacin (4 mg/l) resulted in a 4 log decrease at 6 h, but there were no surviving bacteria at 6 h when combined with amikacin (8 mg/l). The combination of cefepime (16 mg/l) with gentamicin (4 mg/l) resulted in a 4 log decrease in 24 h. The antimicrobial combination of cefepime (32 mg/l) with ciprofloxacin (2 mg/l) resulted in a 4 log decrease in 24 h. Cefpirome (8 mg/l) induced a 2 log decrease at 4 h; 32 mg/l cefpirome resulted in a 3 log decrease followed by regrowth at 24 h. The regrowth observed in the late phase with cefpirome alone disappeared when combined with aminoglycoside. When cefpirome (32 mg/l) was used in combination with ciprofloxacin (1 mg/l), it resulted in a 4 log decrease in 24 h.

The miniature pig is becoming a popular non-rodent animal model in biochemical research because of physiological similarities to humans. In addition, the micropig presents the advantages of large animal species for experimental pharmacokinetics. However, pharmacokinetics of antimicrobial agents are poorly documented in the pig and further work is needed to establish interspecies comparisons. This prompted us to investigate the disposition of three well documented β-lactams (cefepime, cefpirome and meropenem) in this model and also to evaluate the potential to use it for pharmacodynamic studies. Each drug was given following a single dose both by direct intravenous injection (or short infusion for meropenem) and continuous infusion. Six animals were enrolled in each group. Blood samples were obtained over a 0–12 h period, using a catheter placed in the external jugular vein. All β-lactams were assayed by high performance liquid chromatography (HPLC). Pharmacokinetics of cefepime and cefpirome given by bolus injection in the microswine were close to those in man receiving equivalent dosage (i.e. 2 g). The terminal half-lives are similar (human: 1.80 h, 1.80 h; pig: 1.46 h, 1.29 h) as is the case for clearance values (human: 1.82, 1.80; pig: 1.90, 1.74 ml/min per kg) for cefepime and cefpirome, respectively. The administration by continuous infusion does not influence the elimination rate of cefepime, cefpirome and meropenem. Meropenem kinetics in the micropig were also similar to those in man. The terminal half-lives are similar (human, 0.83 h; pig, 0.88 h) as in the case for clearance values (human, 4.0 h; pig, 4.90 ml/min per kg) after 30 min intravenous infusion of meropenem. We concluded that the micropig is an adequate model for the study of the pharmacokinetics and probably the pertinent model for ex-vivo pharmacodynamics investigations of cefepime, cefpirome and meropenem.

A new, well-documented case of Mycobacterium shimoidei infection is reported. This bacterium was isolated from a patient with preexisting pulmonary lesions who developed a tuberculosis-like cavity in the lung. Isolation of fewer than ten strains, not epidemiologically related, has been reported worldwide; all originated from human pulmonary samples. Identification of the strain described here was first accomplished by 16S rDNA direct sequencing after in vitro amplification. This method allows rapid identification of unusual bacteria. The identification was confirmed by specific phenotypical tests and by chromatographic methods.

The penetration of piperacillin-tazobactam in eight mechanically ventilated intensive care patients (age, 56.0 +/- 12.2 years, and weight, 76.5 +/- 15.2 kg [means +/- standard deviations]) with bacterial pneumonia was investigated. They were given intravenous doses of piperacillin (4 g) and tazobactam (0.5 g) as 30-min infusions every 6 h. The kinetic study was performed after the fourth dose on day 2 of treatment. Samples of blood and bronchial secretions (BS) were collected before the fourth dosing and 0.5, 1, 2, 4, and 6 h after the end of infusion. Drug concentrations in both sera and BS were measured by high-performance liquid chromatography. Concentrations (in micrograms per milliliter) in serum were 184.80 +/- 63.03 and 40.03 +/- 30.79 for piperacillin and 23.05 +/- 7.53 and 4.86 +/- 4.54 for tazobactam at 0.5 and 6 h, respectively, after the end of infusion. The corresponding concentrations (in micrograms per milliliter) in BS were 29.33 +/- 25.08 and 20.25 +/- 19.11 for piperacillin and 6.86 +/- 4.25 and 4.25 +/- 2.78 for tazobactam. The percentages for the extent of penetration of piperacillin and tazobactam, as defined by the BS/serum area under the curve ratio, were 35.70 and 78.42%, respectively. These data indicate good penetration of both piperacillin and tazobactam into BS. The concentrations of tazobactam in BS are persistent and high enough to exceed the values found to be effective in vitro against the tazobactam-susceptible beta-lactamases produced by the most important pathogens responsible for nosocomial pneumonia.

Resume La preparation de serums de lapins immunises par des cultures chauffees de souches de Pseudomonas cepacia, selectionnees en fonction de leur biotype et de leur origine geographique, a permis de distribuer 147 souches d'origine hospitaliere (en majorite isolees a Strasbourg) selon 5 serogroupes 0 : 01 (10 %), 02 (69 %), 03 (3 %), 04 (3 %), 05 (3 %), 12 % des souches sont non agglutinables par les immunserums 01 a 05. La valeur du serogroupage 0 comme marqueur epidemiologique de P. cepacia est discutee.

Resume Les bacilles a Gram negatif aerobies stricts se rencontrent de plus en plus frequemment dans les hemocultures, ils posent un probleme de diagnostic bacteriologique et d'interpretation clinique. Nous rappelons les principaux caracteres bacteriologiques de ces germes. D'apres notre etude, portant sur une annee, nous pouvons conclure qu'a l'heure actuelle, hormis Pseudomonas aeruginosa (B. pyocyanique) et Moraxella ( Acinetobacter ), les autres Pseudomonas et germes voisins aerobies stricts sont essentiellement des contaminants de l'environnement hospitalier. Ce n'est que dans de rares cas que l'on peut leur attribuer la responsabilite d'un etat septicemique. Pour permettre une interpretation plus objective d'une hemoculture positive, nous preconisons d'effectuer une numeration des germes dans le sang avant sa mise en culture.

Resume Nous avons etudie la sensibilite de plusieurs especes de Pseudomonas et de Flavobacterium vis-a-vis de la ticarcilline, des acylureidopenicillines, des cephalosporines de troisieme generation et de deux nouvelles quinolones. La sensibilite globale de Flavobacterium , faible a la ticarcilline, mediocre aux acylureidopenicillines, n'est guere amelioree par l'introduction de ces cephalosporines et de ces quinolones. Le modele de P. aeruginosa n'est pas integralement applicable a toutes les especes de Pseudomonas . Les acylureidopenicillines et la ceftazidime sont en general actives sur la plupart des especes a l'exception de P. maltophilia . Lors d'une infection a bacilles a Gram (−) non fermentatifs, l'antibiogramme classique devra s'elargir a des molecules plus recentes, notamment la ciprofloxacine qui pourrait constituer une nouvelle perspective dans l'antibiotherapie de ces infections a germes opportunistes.

Resume Aerococcus viridans , caracteristique des atmospheres confinees, peut devenir un germe opportuniste et causer des surinfections chez des malades predisposes en milieu hospitalier. La frequence de son isolement peut augmenter en bacteriologie hospitaliere et il importe de la distinguer aisement des staphylocoques, des streptocoques alpha hemolytiques avec lesquels il est certainement souvent confondu si l'on s'attache seulement a l'aspect des colonies. L'etude clinique que nous avons menee a l'occasion de l'isolement de 15 souches d' A. viridans permet d'avancer parmi les causes favorisantes de surinfections hospitalieres dues a ce germe : le diabete, les immunodepresseurs, l'ethylisme et la stase vesicale lors des infections urinaires.

Nous rapportons l'observation de diarrhees survenues selon un mode epidemique dans un service d'enfants et au cours desquelles, dans un premier temps, aucun agent causal ne fut mis en evidence en suivant les regles classiques de la coproculture. En effect, ce n'est que tardivement que nous avons ete amenes a etudier des souches de E. coli lactose (−), isolees systematiquement dans les selles de ces enfants. Nous avons pu determiner qu'il s'agissait de E. coli 111 B:4 lactose (−). Cette particularite nous a permis de disposer d'un marqueur epidemiologique commode et, par la suite, de suivre le cheminement de l'infection hospitaliere. Nous avons pu ainsi reconstituer la propagation de l'epidemie de ce «mutant lactose (−) de E.coli 111 B:4 chez quarante-cinq enfants entre le 12 mai 1971 et le 28 octobre 1971 (depuis cette date, nous avons trouve seize nouveaux cas). Trente et un enfants etaient hospitalises dans le service de Pediatrie et Puericulture I, quatre sujets etant places dans une creche mais l'un d'eux, qui a probablement contamine les autres, avait sejourne, au prealable, dans le service. Dix enfants appartenant a une autre collectivite de nourrissons avaient ete contamines par l'un d'eux sortant toujours de ce meme service.

Depuis deux ans, dans le cadre des examens du laboratoire de bacteriologie du Centre Hospitalier Regional de Strasbourg, nous effectuons le groupage de toutes les souches de streptocoques beta hemolytiques isolees. Il nous a paru interessant de dresser le bilan de ces deux annees de travail et de faire une etude comparative de l'importance des trois groupes principaux: A, B et C.

To determine the utility of available Pseudomonas cepacia typing systems for confirming the relatedness of isolates, we applied these methods to isolates associated with previously investigated nosocomial outbreaks. We compared chromosome analysis, serologic reactions, biochemical tests, bacteriocin production and susceptibility, and antimicrobial susceptibility in their ability to determine outbreak relatedness. Chromosome analysis, serologic reactions, and biochemical tests were each demonstrated to be epidemiologically useful methods for typing isolates. Determination of the sensitivity and specificity of these typing techniques will facilitate their application in the epidemiologic study of this increasingly important nosocomial pathogen.

Over a 14-month period, 415 clinical isolates of coryneform gram-positive rods were recovered from various sources and identified to the species level according to recent identification schemes. Corynebacterium urealyticum, Corynebacterium striatum, Corynebacterium amycolatum, and Corynebacterium jeikeium predominated, accounting for 63% of all isolates. Corynebacterium accolens, Corynebacterium striatum, Corynebacterium argentoratense, Corynebacterium propinquum and Corynebacterium pseudodiphtheriticum were mostly recovered from the respiratory tract, whereas Corynebacterium afermentans, CDC group G, and Corynebacterium jeikeium were mainly isolated from blood. None of the isolates was identified as Corynebacterium diphtheriae or Corynebacterium xerosis. Ampicillin resistance was detected in Corynebacterium jeikeium (96%) and Corynebacterium urealyticum (99%) and varied among Corynebacterium amycolatum (56%) and CDC group G (26%). These data emphasize the need for an accurate identification of coryneform organisms at the species level and for antimicrobial susceptibility testing of these organisms.