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PubMed1999

Development of resistance and cross-resistance in Pseudomonas aeruginosa exposed to subinhibitory antibiotic concentrations.

The purpose of this study was to compare resistance and cross-resistance development in Pseudomonas aeruginosa isolates from cystic fibrosis (CF) patients to commonly used antipseudomonal antibiotics. Isolates were repeatedly exposed to subinhibitory concentrations of either azlocillin, tobramycin, ceftazidime or ciprofloxacin. On 10 consecutive occasions, samples were removed from the half-MIC well of a microtitre plate and regrown in drug-free medium to provide the next inoculum for MIC determination. The increase in MIC at the end of the treatment period was significant (p<0.05) for all selecting antibiotics. Cross-resistance to unrelated antibiotics was not observed, but was significant (p<0.05) in all beta-lactams (ticarcillin, piperacillin, ceftazidime and cefsulodin) studied where azlocillin was the selecting antibiotic. The addition of clavulanic acid to ticarcillin and of tazobactam to piperacillin had no effect on cross-resistance. The development of resistance to azlocillin was associated with increased beta-lactamase activity and a change in isoelectric point of the beta-lactamases. The result of this study supports a rotational policy for antipseudomonal antibiotics in CF patients.

Anti-Bacterial Agents↗
PubMed1989

Comparison of in vitro susceptibilities among gram-negative rods.

The activity of mezlocillin, azlocillin and piperacillin was compared using 100 clinical isolates of gram-negative rods. Overall piperacillin had the highest activity with 72 per cent sensitive strains; mezlocillin, 66 per cent, and azlocillin, 57 per cent. In the group of Pseudomonas aeruginosa, however, mezlocillin showed distinctly lower activity than both piperacillin and azlocillin.

Azlocillin↗
PubMed1986

[Value of bactericidal curves in the optimal selection of a beta-lactam-aminoglycoside combination on Pseudomonas aeruginosa. In vitro study of 40 strains of Pseudomonas aeruginosa isolated in pediatric intensive care units].

Antimicrobial sensitivity and time-kill curves were determined for ticarcillin, azlocillin, piperacillin, cefsulodin, ceftazidime, gentamicin, tobramycin and amikacin alone or in combination against 40 strains of Pseudomonas aeruginosa isolated from blood cultures and tracheal aspirates in pediatric intensive care units. The antibiotics were used in concentrations obtainable with the usual therapeutic dosage. No bactericidal effect was observed with each of the beta-lactam antibiotics tested alone. For ticarcillin-sensitive strains the most rapid bacterial inoculum size decrease was observed at 2.5 h with the piperacillin-amikacin combination, and a bactericidal effect was obtained within 4.5 h when amikacin was combined with ticarcillin, azlocillin, piperacillin, ceftazidime or cefsulodin. For ticarcillin-resistant strains a bactericidal effect was obtained within 4.5 h when amikacin was combined with piperacillin, azlocillin, ceftazidime or cefsulodin.

Amikacin↗
PubMed1981

Evaluation of therapeutic efficacy of ureidopenicillins in comparison to sisomicin and cephalotin in experimental infections of rabbits.

The therapeutic efficacy of azlocillin, mezlocillin, cephalotin, and sisomicin was evaluated by experimental infection in rabbits. After one hour following infection with Escherichia coli, Klebsiella pneumoniae or Pseudomonas aeruginosa, antibiotics were applied intramuscularly. Colony-forming units were counted before the infection and every day thereafter. Leukocytosis was determined before infection and 3 and 7 days after initiation of therapy. Therapy with antibiotics was continued for seven days, rabbits sacrificed and CFU/g tissue determined. It was shown that in experimental infection caused by E. coli or K. pneumoniae in rabbits, sisomicin was most effective, followed by mezlocillin, azlocillin, and cephalotin. Efficacy of therapy against P. aeruginosa was as follows: sisomicin, azlocillin, mezlocillin.

Animals↗
PubMed1982

The in vitro activity of beta-lactam antibiotics against gentamicin and/or carbenicillin-resistant Pseudomonas aeruginosa strains.

We studied the behaviour of 56 clinical isolates of Pseudomonas aeruginosa strains against the following beta-lactam antibiotics: cefotaxime, cefoperazone, cefsulodin, lamoxactam, Ro 13-9904, azlocillin, mezlocillin and ticarcillin. Twenty-six strains were resistant to gentamicin and 30 to gentamicin and/or carbenicillin. The MICs were measured by the serial dilution test on solid agar. Cefsulodin was the most active cephalosporin against carbenicillin-resistant strains (MIC greater than or equal to 128 mg/l); it inhibited 56.6% of these strains at a concentration of 8 mg/l. Azlocillin was the most active penicillin, inhibiting 79.96% of the same strains at a concentration of 64 mg/l. Cefsulodin was the most active cephalosporin against the gentamicin-resistant group of Pseudomonas aeruginosa strains (MIC greater than or equal to 8 mg/l) which were sensitive to carbenicillin (MIC less than or equal to 64 mg/l). It inhibited 100% of the strains at a concentration of 4 mg/l. All of the penicillins studied inhibited all of the strains in this group. The required concentrations were the following: 16 mg/l for azlocillin, 32 mg/l for mezlocillin and 64 mg/l for ticarcillin.

Anti-Bacterial Agents↗
PubMedDate not supplied

Susceptibility and tolerance of beta-lactamase-producing, methicillin-sensitive strains of Staphylococcus aureus towards seven broad-spectrum penicillins.

The activity of penicillin G, ampicillin, carbenicillin, ticarcillin, azlocillin, mezlocillin and piperacillin against 102 beta-lactamase-producing, methicillin-sensitive strains of Staphylococcus aureus was determined by agar dilution (method A) and broth microdilution (method B) techniques. By NCCLS breakpoint criteria, 4% of the strains were "sensitive" to penicillin and ampicillin, and almost 100% were "sensitive" to the other drugs when method A was used. Results with method B were only significantly lower as far as the cumulative percentage of strains "sensitive" to azlocillin, mezlocillin and piperacillin was concerned (63-71%). Bactericidal effects at "sensitive" levels were observed in 0-2% (penicillin, ampicillin), 31-35% (carbenicillin, ticarcillin) and 10-14% (azlocillin, mezlocillin, piperacillin). While differences in MIC and MBC levels ranged from 0 to 8 dilution steps, tolerance (a greater than 32-fold difference) was seen in at least 9-22% of all strains (depending on the drug tested); experimental limitations, however, excluded a determination of tolerance in all our strains. In a semi-quantitative nitrocefin assay, "strong" beta-lactamase production was correlated to high MIC and/or MBC levels.

Drug Tolerance↗
PubMed1987

Antimicrobial chemotherapy in patients with cystic fibrosis.

The treatment of exacerbations of pulmonary infections due to Pseudomonas aeruginosa in patients with cystic fibrosis is unsatisfactory. Serum concentrations and urinary excretion of cephalexin, epicillin, azlocillin, ticarcillin, trimethoprim-sulfa and gentamicin useful in the treatment of these infections were investigated in cystic fibrosis patients suffering from pulmonary infections. The data were compared to those found in non-cystic fibrosis children treated with antibiotics for other reasons. Cephalexin and trimethoprim are absorbed at a slower rate; epicillin, azlocillin, ticarcillin sulfonamides were eliminated at a faster rate by the kidneys which was unique to patients with cystic fibrosis. Gentamicin is also eliminated faster. Further investigations disclosed that a considerable amount of drug is eliminated by tubular secretion in addition to the regular glomerular filtration in patients with cystic fibrosis. Creatinine clearance values were determined in these patients and found to be normal. By doubling the dose of gentamicin and administration as infusion over 90 min, higher serum and tissue concentrations were achieved without being in the toxic range. The clinical relevance of these investigations was determined in 36 patients and 48 episodes of infection with P. aeruginosa. Patients received gentamicin 4 mg/kg BW as i.v. infusion over 90 min q. 8 h and azlocillin or ticarcillin 120-160 mg/kg BW q. 8 h, applied 4 h later. In 14 patients respectively 27 episodes, pseudomonas was eradicated from the sputum for a minimum of three weeks, and in most of them for 12-24 weeks. No side effects were observed from the higher doses of aminoglycosides.

Absorption↗
PubMed1994

Relation between resistance to beta-lactam antibiotics and cadmium in salmonellae isolated from pigs.

Of 50 Salmonella species isolated from pigs, 30 were resistant to cadmium and 18 of these also to azlocillin. The azlocillin-resistant isolates were resistant to cadmium at 80-500 mg/L CdSO4. A broader spectrum of resistance to azlocillin, ampicillin and cephazolin was found in strains resistant to < 200 mg/L CdSO4. Resistance to silver, mercury, chloramphenicol and streptomycin was independent of the resistance to beta-lactam antibiotics and Cd2+. Production and levels of beta-lactamase do not correlate with the spectrum of resistance.

Animals↗
PubMed1985

Apalcillin [PC-904]: spectrum of activity and beta-lactamase hydrolysis/inhibition.

Apalcillin is a Pseudomonas-active penicillin with a broad spectrum of antibacterial activity similar to that of piperacillin, except for the greater potency of apalcillin against Acinetobacter spp. and Pseudomonas aeruginosa. Studies with 846 isolates representative of the common bacterial pathogens compared apalcillin to piperacillin, azlocillin, mezlocillin, carbenicillin, ticarcillin, cefotaxime, and cefoperazone. Apalcillin and piperacillin were both active against all 13 species of the Enterobacteriaceae that were tested (MIC 50s less than or equal to 8.0 micrograms/ml) but some strains were resistant to both penicillins. Apalcillin was active against Pseudomonas aeruginosa and Acinetobacter spp. (MIC 50 less than 2.0 micrograms/ml). Like other penicillins, apalcillin was not effective against beta-lactamase-producing Staphylococcus spp., Haemophilus spp. or Neisseria gonorrhoeae. Rates of hydrolysis by six beta-lactamase preparations from gram-negative bacilli were determined, comparing apalcillin, piperacillin, azlocillin, ticarcillin, ampicillin and dicloxacillin to benzyl penicillin. Apalcillin and ticarcillin were more resistant than piperacillin and azlocillin to hydrolysis by the PSE-2 enzyme from P. aeruginosa. As did many other penicillins, apalcillin inhibited the Type 1 beta-lactamase that is produced by Enterobacter cloacae. The other enzymes were inhibitory only in very high concentrations.

Ampicillin↗
PubMed1984

Studies of in vitro synergy between several beta-lactam and aminoglycoside antibiotics against endocarditis strains of Pseudomonas aeruginosa.

Ten strains of Pseudomonas aeruginosa isolated from patients with endocarditis (1969-1975) and eight similar strains (1980) were assayed for minimum inhibitory concentrations (MICs) and minimum bactericidal concentrations (MBCs) to several aminoglycosides (gentamicin, tobramycin, amikacin) and beta-lactam antibiotics (ticarcillin, piperacillin, azlocillin, moxalactam and MKO 787). In vitro synergy (1969-1975 series) between beta-lactam and aminoglycoside antibiotics was shown uniformly with azlocillin (100 per cent) followed by moxalactam (80 per cent), piperacillin and ticarcillin (66 per cent) and MKO 787 (13.3 per cent). Results were similar in 1980. Synergy of azlocillin was demonstrated with five strains previously not showing synergy between carbenicillin and an aminoglycoside. In 1980 four of eight patients infected with pseudomonads that were not synergistically affected in vitro were refractory to treatment with the piperacillin-aminoglycoside combination. In vitro synergy of the infecting strain is necessary for successful medical treatment of patients with P. aeruginosa infective endocarditis.

Aminoglycosides↗
PubMed1988

Degradation of acylaminopenicillins with regard to their pH dependency.

Determination of antibiotic concentration is performed in many biological fluids and tissues which all have different pH values. Therefore, we investigated the in vitro stability of three acylaminopenicillins (azlocillin, mezlocillin and piperacillin) in borate buffer by the HLPC technique with regard to pH dependency. HPLC allows the detection of all three substances together with their metabolites, penicilloate and penilloate, within 15 min. Decomposition was monitored at 37 degrees C during a 24 h incubation period (pH values ranged between pH 3.0 and 10.0). The highest degradation rates were observed with a buffer solution of pH = 10.0: 50% of the azlocillin and 83% of the mezlocillin were decomposed after 8 h while under the same conditions, piperacillin was completely decomposed already after 1 h. The highest stability was detected in borate buffer at pH values of 4.0, 5.0, and 6.0. At pH = 3.0, degradation was determined as follows: 31% of the piperacillin, 39% of the mezlocillin, and 45% of the azlocillin were decomposed after 24 h. Penilloic acid was identified as the main metabolite in contrast to buffer solutions with higher pH values which only revealed negligible amounts of this compound.

Acetonitriles↗
PubMed1979

Bacteriological studies with cefsulodin (CGP 7174/E), the first antipseudomonal cephalosporin.

The new cephalosporin, cefsulodin, has considerable antibacterial activity against Pseudomonas aeruginosa. When 217 strains of Ps. aeruginosa were tested against both azlocillin and cefsulodin, 26.3% were found to have the same minimal inhibitory concentration (MIC); the MIC for azlocillin was lower than that for cefsulodin in 16.6% of strains, but higher in 57.1%. 22 gentamicin-resistant strains were all susceptible to cefsulodin. Biophotometer investigations demonstrate less bactericidal effects for cefsulodin and azlocillin than for carbenicillin and ticarcillin using higher inocula than used in the agar of tube dilution test. Cefsulodin and gentamicin are synergistic against Ps. aeruginosa. Using high pressure liquid chromatography and biological techniques, cefsulodin is found to be moderately stable in solution and in standard solid laboratory media.

Anti-Bacterial Agents↗
PubMedDate not supplied

Comparative activity of newer antibiotics against gram-negative bacilli.

The in vitro activities of cefoperazone, cefotaxime, ceftriaxone, ceftazidime, azlocillin, mezlocillin, piperacillin, ticarcillin/clavulanate, aztreonam, imipenem, and ciprofloxacin were concurrently determined against over 1,000 isolates of gram-negative bacilli from clinical specimens of patients at the Cleveland Clinic. Cephalosporins, penicillins, and aztreonam were active against species of Enterobacteriaceae other than Citrobacter freundii, Enterobacter aerogenes, and Enterobacter cloacae. Ceftazidime was the most active cephalosporin against Pseudomonas aeruginosa. Against the Enterobacteriaceae, the rank order of activity of penicillins was ticarcillin/clavulanate greater than piperacillin greater than mezlocillin greater than azlocillin. Against P. aeruginosa, the rank order of activity of penicillins was piperacillin greater than ticarcillin/clavulanate greater than azlocillin greater than mezlocillin. Aztreonam was less active v P. aeruginosa than ceftazidime, cefoperazone, or piperacillin. The most active antimicrobials against all isolates tested were imipenem and ciprofloxacin.

Aztreonam↗
PubMed1986

Bacteriological and ultrastructural studies on the effect of subinhibitory beta-lactam concentrations on intraphagocytic killing of Pseudomonas aeruginosa by human polymorphonuclear leukocytes.

The effect of azlocillin, ticarcillin and cefsulodin, respectively, on the susceptibility of Pseudomonas aeruginosa to the antimicrobial action of human polymorphonuclear leukocytes (PMN) was investigated under two different experimental conditions. Firstly, phagocytic capacity as well as bactericidal activity of PMN were assessed in a homologous system, i.e. the clinical isolate as well as the PMN and serum were obtained from the same patient. Secondly, ultrastructural studies were performed by electron microscopy. Preincubation of bacteria with subinhibitory beta-lactam concentrations augmented the phagocytic capacity as well as the antibacterial activity of PMN; azlocillin tended to be the most effective drug in this respect. The enhanced susceptibility to leukocyte killing is not due to an increased antibacterial action of the beta-lactams in the presence of PMN. These findings suggest that a non-immunological linkage between bacteria and PMN may exist which may be based on the interaction between bacterial- and eukaryotic surface structures, respectively. It may be assumed that the antipseudomonal beta-lactam antibiotics may cause changes in the surface structures of P. aeruginosa, thus rendering them more susceptible to phagocytosis. Preliminary data indicate that the lectins on the outer membrane of P. aeruginosa are not mannose sensitive. Electron microscopic studies revealed that azlocillin pretreatment of bacteria brought about a high undulation and a disruption of the outer membrane. These morphological changes may render bacteria more vulnerable to the antimicrobial action of PMN. It may be speculated that an interference with surface adhesins and induction of morphological changes may affect engulfment and intracellular killing of bacteria.

Anti-Bacterial Agents↗
PubMed1986

In vitro comparison of antiplatelet effects of beta-lactam penicillins.

beta-Lactam antibiotics have been shown to cause platelet dysfunction and bleeding in some patients. However, relative antiplatelet activity of various beta-lactams has remained controversial. Results of clinical studies have been variable because of the presence of underlying disease in the study patients, in addition to inherent difficulties of in vivo experimentation such as individual variations of drug metabolism and drug kinetics. Thus, we designed in vitro experiments to study the direct effect of penicillin G, carbenicillin, ticarcillin, mezlocillin, piperacillin, nafcillin, and azlocillin on platelets. Platelets obtained from normal volunteers were exposed in vitro for 15 minutes to increasing concentrations of the test penicillins (10.0, 12.5, 15.0, and 20.0 mmol/L), and the platelet aggregation response determined after the additional of adenosine diphosphate (2.5 to 5.0 mumol/L), epinephrine (0.1 X 10(-3) mol/L), thrombin (0.01 to 0.02 U/ml), and collagen (11.62 micrograms/ml). All tested penicillins inhibited platelet aggregation in a saturable dose-dependent manner that was reversible by platelet washing. Biostatistical comparison of inhibition of platelet aggregation demonstrated nafcillin to cause significantly more inhibition, followed by azlocillin, mezlocillin, and piperacillin as a group. Penicillin G, carbenicillin, and ticarcillin were the least inhibitory. The mean percent inhibition (epinephrine) at 20 mmol/L concentration was nafcillin 86.4%, mezlocillin 83.2%, piperacillin 80.3%, azlocillin 76.4%, ticarcillin 73.2%, carbenicillin 66.4%, and penicillin G 58.4% (overall P less than 0.001). We conclude that all penicillins tested in vitro inhibit platelet aggregation in normal individuals, but to varying degrees. The inhibitory response, which is most likely a membrane-related phenomenon, is dose dependent and reversible.

Adenosine Diphosphate↗
PubMed1982

[Activity of new beta-lactam antibiotics].

The antibacterial activity of the newer beta-lactam compounds mezlocillin, cefuroxime, cefotaxime, ceftizoxime, cefoperazone, lamoxactam, and cefsulodin was evaluated in 335 strains of ampicillin-resistant (MIC greater than 16 mg/l) enterobacteria, 50 pseudomonas aeruginosa, 28 acinetobacter species, and 50 streptococcus faecalis isolates. With the exception of some strains, enterobacteria were inhibited by low levels of cefotaxime and ceftizoxime, respectively. Between these both compounds there was an almost complete cross-resistance. In each species lamoxactam inhibited at least 90% of the isolates. The antibacterial activity of cefoperazone against enterobacteria was decreased; however, it was active against pseudomonas aeruginosa exhibited antibacterial activity comparable to that of azlocillin. Cefsulodin proved to be the most active drug against pseudomonas aeruginosa exceeding to some extent even piperacillin. Ceftizoxime was the most active drug against acinetobacter species. Among the new cephalosporins, it was only cefoperazone that exhibitediting antibacterial activity comparable to that of azlocillin. Cefsulodin proved to be the most active drug against pseudomonas aeruginosa exceeding to some extent even piperacillin. Ceftizoxime was the most active drug against acinetobacter species. Among the new cephalosporins, it was only cefoperazone that exhibitediting antibacterial activity comparable to that of azlocillin. Cefsulodin proved to be the most active drug against pseudomonas aeruginosa exceeding to some extent even piperacillin. Ceftizoxime was the most active drug against acinetobacter species. Among the new cephalosporins, it was only cefoperazone that exhibited some activity against streptococcus faecalis, which was comparable to that of cephalothin, but markedly impaired to that of cefazedone. With respect to streptococcus faecalis, the penicillin derivatives still remain the by far most active compounds.

Acinetobacter↗
PubMed1982

[Comparative activity of cefsulodin on Pseudomonas aeruginosa, Acinetobacter and Enterobacteriaceae (author's transl)].

Cefsulodin, a new semi-synthetic cephalosporin, is characterized by its activity against P. aeruginosa. In this study the authors compared this new molecule with other four betalactamines, carbenicillin, ticarcillin, azlocillin and mezlocillin, and two aminoglycosides, amikacin and netilmicin. Two hundred and forty five strains studied were 100 Pseudomonas aeruginosa, 20 Acinetobacter, 42 Proteus, 21 Serratia, 22 Enterobacter, 20 Klebsiella and 20 E. coli. One hundred twenty strains of these showed carbenicillin resistant phenotype. MIC were determined by the agar dilution method. Cefsulodin was only active on Pseudomonas aeruginosa. MICs were at least 16 mg/l in the other species. On carbenicillin susceptible P. aeruginosa strains, the average MIC of cefsulodin, amikacin and netilmicin was 1 mg/l, and MICs of azlocillin, mezlocillin, ticarcillin and carbenicillin were 4-8 mg/l, 8 mg/l, 16 mg/l and 32 mg/l, respectively. On carbenicillin resistant P. aeruginosa, ticarcillin and mezlocillin were not effective and MICs of azlocillin and cefsulodin were 16 mg/l and 4-8 mg/l, respectively. However, MICs were between 64 and 128 mg/l in 20 p. cent of carbenicillin resistant strains.

Acinetobacter↗
PubMed1982

[Comparative bactericidal activity of beta-lactam-aminoglycoside combinations against Pseudomonas aeruginosa].

The effects of combining each of 10 beta-lactamins (carbenicillin, ticarcillin, piperacillin, azlocillin, cefotaxime, moxalactam, ceftriaxone, cefoperazone, ceftazidime, cefsulodin) with 6 aminoglycosides were studied in vitro against two strains of Pseudomonas aeruginosa. The bactericidal activity was tested by two methods: solid medium technique of "cellophane transfer" and "checkerboard" method (broth-dilution micromethod partly automatic). No single antagonism was observed. Concerning new penicillins, the percentage of synergy is increasing from carbenicillin, to ticarcillin, to azlocillin and finally to piperacillin. For recent cephalosporins, the most synergistic combinations are obtained with ceftriaxone, cefoperazone and ceftazidime. If aminoglycosides associations are considered, there is a good activity whichever antibiotic chosen, with a higher level for streptomycin and lower one for tobramycin. Dibekacin combinations, also tested by the checkerboard method, are particularly synergistic with azlocillin and piperacillin for new penicillins, and equally well with ceftriaxone for recent cephalosporins.

Aminoglycosides↗