Selective digestive decontamination by erythromycin-base in a polyvalent intensive care unit.

OBJECTIVE: To study the effect of selective digestive tract decontamination by erythromycin-base on the incidence of carriage and infection with MR Enterobacteriaceae producing an extended spectrum beta-lactamase (ESB). DESIGN: After a 10-week prospective survey to ascertain the baseline incidence in two bays (1 and 3) of the same ICU, bay 1 was compared with bay 3 during a further survey of 6 months. The patients in bay 1 received erythromycin-base. SETTING: Two non-contiguous bays, 1 and 3, of 4 beds, in the same polyvalent ICU of a university hospital. PATIENT: Consecutive patients with unit stay longer than 2 days; 34 patients were included during the control period, 43 in bay 1 (decontamination) and 46 in bay 3 (control) during the trial period. INTERVENTION: Erythromycin-base, 1 g t.i.d. in powder form administered by gastric tube to patients in bay 1 from admission to discharge. MEASUREMENTS AND RESULTS: Digestive tract carriage was monitored by cultures of gastric and rectal swab specimens, sampled twice a week. Enterobacteriaceae were isolated on Drigalski agar with incorporated ceftazidime (4 mg/l). In bay 1 there was a decrease in ESB producing Enterobacteriaceae (23% vs 10%, p = 0.0004) from rectal swab, especially in K. pneumoniae (15% vs 2%, p = 10(-5)), during the decontamination period in comparison to the control period. During the trial period the only differences observed between bays 1 and 3 were in the gastric samples: K. pneumoniae were less often isolated in bay 1 than in bay 3 (0% vs 3%, p = 0.03). Intestinal carriage with multiresistant Enterobacteriaceae occurred in 28% patients in bay 1 and 30% patients in bay 3 during the trial period (p = 0.79). Erythromycin-base did not delay the carriage by patients in bay 1 (log rank test p = 0.42). CONCLUSION: Erythromycin-base was not effective in preventing digestive tract carriage due to Enterobacteriaceae resistant to third generation cephalosporin by production of chromosomal cephalosporinase. The decrease in isolates containing K. pneumoniae in bay 1 cannot be definitively attributed to erythromycin-base, since the number of this species in bay 3 was low.

[Antibacterial activity of minocycline alone and associated with other antibiotics (author's transl)]. / Activité antibactérienne de la minocycline seule et associée à d'autres antibiotiques

The authors study in vitro effects of minocycline and compare its activity with tetracycline. 909 strains of cocci and bacilli selected among strains isolated from Clermont-Ferrand Hospital Center during the third trimester 1974 were used. Study involves 3 parts : comparison between bacteriostatic activity of both antibiotics ; evaluation of R-factor resistance ; evaluation of bactericidal activity of antibiotic associations including minocycline. M.I.C. study included all strains. A better bacteriostatic activity was noted with minocycline against multi-resistant strains of staphylococcus, streptococcus, E. coli, Serratia and Moraxella. R-factor resistance has been studied upon 27 strains of Gram-negative bacilli selected for their high M.I.C. to tetracycline (M.I.C. greater than or equal to 64 mcg/ml) and to minocycline (M.I.C. greater than or equal to 32 mcg/ml). Both types of transferable tetracycline resistance characters Ta and Tb have been found. More than 250 bactericidal associations were studied upon 38 strains.

Multiplicity of TEM-derived beta-lactamases from Klebsiella pneumoniae strains isolated at the same hospital and relationships between the responsible plasmids.

Five plasmid-mediated beta-lactamases conferring high-level resistance to ceftazidime were isolated from Klebsiella pneumoniae strains in the same hospital. These enzymes had isoelectric points ranging from 5.3 to 6.5 (CAZ-1, 5.55; CAZ-2, 6.0; CAZ-3, 5.3; CAZ-6, 6.5; and CAZ-7, 6.3). All isolates and their Escherichia coli transconjugants were highly resistant to amoxicillin (MICs, greater than 4,096 micrograms/ml), piperacillin (64 to 256 micrograms/ml), cephalothin (32 to 256 micrograms/ml), and ceftazidime (32 to 512 micrograms/ml) but remained moderately susceptible to cefotaxime (0.5 to 8 micrograms/ml). Only CAZ-6- and CAZ-7-producing strains were highly resistant to aztreonam (64 to 128 micrograms/ml). All the isolates remained susceptible to moxalactam and imipenem. The reduced activity of piperacillin, cefotaxime, ceftazidime, or aztreonam was restored by 2 micrograms of clavulanate, sulbactam, tazobactam, or brobactam per ml for E. coli producing CAZ-2, CAZ-3, and CAZ-7. Sulbactam had a lower protective effect than other inhibitors for E. coli harboring CAZ-1 and especially CAZ-6. Except for CAZ-1, which was mediated by a 150-kilobase (kb) plasmid (pCFF14), the other ceftazidimases were mediated by plasmids of 85 kb with EcoRI digestion patterns similar to that of pCFF04 encoding CTX-1 beta-lactamase. A TEM probe hybridized with a 19-kb EcoRI fragment of all these closely related plasmids.

Novel plasmid-mediated beta-lactamase in clinical isolates of Klebsiella pneumoniae more resistant to ceftazidime than to other broad-spectrum cephalosporins.

Multiresistant Klebsiella pneumoniae strains isolated from three patients in the same intensive care unit were more resistant to ceftazidime than to cefotaxime and aztreonam but remained susceptible to moxalactam and imipenem. Resistance to beta-lactams, kanamycin, streptomycin, sulfonamides, and tetracyclines was transferable to Escherichia coli by conjugation and was lost en bloc after treatment with ethidium bromide. Agarose gel electrophoresis of wild types and transconjugants indicated that these resistances were mediated by a 150-kilobase plasmid, pCFF14. The strains constitutively produced a beta-lactamase with isoelectric point close to 5.6 and which had a higher Vmax for ceftazidime and cephalothin than for cefotaxime. The substrate profile and isoelectric point of this enzyme thus differ from those of other known plasmid-mediated beta-lactamases, including the broad-spectrum enzyme CTX-1. Hybridization studies support the derivation of the novel enzyme from a TEM-type beta-lactamase.

Comparative study of a novel plasmid-mediated beta-lactamase, CAZ-2, and the CTX-1 and CAZ-1 enzymes conferring resistance to broad-spectrum cephalosporins.

Infections caused by strains of Klebsiella pneumoniae resistant to broad-spectrum cephalosporins have been observed recently in hospitals in Clermont-Ferrand, France. beta-Lactam resistance resulted primarily from the plasmid-mediated, expanded-spectrum CTX-1 beta-lactamase. Furthermore, since 1987 some K. pneumoniae isolates more resistant to ceftazidime than to other cephalosporins have been observed. This new resistance phenotype was the result of the production of ceftazidimase CAZ-1 and, more recently, CAZ-2. As in CTX-1-producing strains, resistance to beta-lactams resulting from CAZ-2 was associated with resistance to aminoglycosides except gentamicin, sulfonamide, and tetracycline and was transferable to Escherichia coli by conjugation. Agarose gel electrophoresis of plasmid DNA from wild-type strains and transconjugants indicated that CAZ-2 production was mediated by a plasmid of 85 kilobases highly related to plasmid pCFF04 coding for CTX-1 beta-lactamase. The isoelectric point, close to 6.0, of this novel enzyme differed from those of CTX-1 and CAZ-1. Like CAZ-1, the CAZ-2 enzyme efficiently hydrolyzed ceftazidime and aztreonam, but as with CTX-1, cefotaxime gave the maximal reaction rate. For each expanded-spectrum beta-lactamase, the activity of broad-spectrum cephalosporins was restored by clavulanic acid or sulbactam.