The cooperation of cefotaxime and desacetyl-cefotaxime with respect to antibacterial activity and beta-lactamase stability

Dose optimization of cefotaxime as pre-emptive treatment in critically ill adult patients: A population pharmacokinetic study

AIMS

To describe the pharmacokinetics (PK) of cefotaxime as pre-emptive treatment in critically ill adult patients, including covariates and to determine the probability of target attainment (PTA) of different dosage regimens for Enterobacterales and Staphylococcus aureus.

METHODS

Five samples were drawn during 1 dosage interval in critically ill patients treated with cefotaxime 1 g q6h or q4h. PK parameters were estimated using NONMEM (v7.4.2). The percentage of patients reaching 100% fT>MIC_ECOFF was used to compare different dosage regimens for Enterobacterales and S. aureus.

RESULTS

This study included 92 patients (437 samples). The best structural model was a 2-compartment model with a combined error, interindividual variability on clearance, central volume and intercompartmental clearance. Correlations between interindividual variability were included. Clearance increased with higher estimated glomerular filtration rate (eGFR; creatinine clearance) and albumin concentration. For Enterobacterales, 1 g q8h reached 95% PTA and continuous infusion (CI) of 4 g 24 h^-1 100% PTA at the highest eGFR and albumin concentration. For S. aureus the predefined target of 95% PTA was not reached with higher eGFR and/or albumin concentrations. CI of 6 g 24 h^-1 for S. aureus resulted in a minimum of 99% PTA.

CONCLUSION

Cefotaxime PK in critically ill patients was best described by a 2-compartment model with eGFR and albumin concentration as covariates influencing clearance. For Enterobacterales 1 g q8h or CI of 4 g 24 h^-1 was adequate for all combinations of eGFR and albumin concentration. For S. aureus CI of 6 g 24 h^-1 would be preferred if eGFR and albumin concentration exceed 80 mL min^-1 and 40 g L^-1 respectively.

Validation of an HPLC method for estimation of cefotaxime from dried blood spot: alternative to plasma-based PK evaluation in neonates

Aim: Pharmacokinetic evaluation of cefotaxime in neonates is currently a challenge due to the large volume requirement of blood for its analysis by existing methods. A dried blood spot (DBS) based method is the best alternative. Materials & methods: We validated an HPLC method for estimation of cefotaxime from DBS and plasma. Extraction employed a simple procedure using acetonitrile and buffer. Selective separation of cefotaxime was achieved on a C8 column using gradient programming. Results & conclusion: The linearity of the method ranged from 2 to 200 μg/ml with acceptable precision and accuracy for both plasma and DBS. Hematocrit was not affecting the assay accuracy. A strong correlation and interchangeability observed with the plasma method proves its clinical validity for application to PK evaluations.

A murine model to study the gut bacteria parameters during complex antibiotics like cefotaxime and ceftriaxone treatment

Background

The globally increasing resistance due to extended-spectrum beta-lactamase producing Enterobacteriaceae is a major concern. The objective of this work was to develop a murine model to study the gut bacteria parameters during complex antibiotics like cefotaxime and ceftriaxone treatment and to compare the fecal carriage of ESBL-producing Enterobacteriaceae.

Methods

SWISS mice were treated either with ceftriaxone or with cefotaxime or with NaCl 0.9% as a control group from day 1 to day 5. We performed a gavage at day 4 with a Klebsiella pneumonia CTX-M9. We collected stools and performed pharmacological measurements, cultures and 16S rRNA gene amplification and sequencing during the 12 days of the stool collection.

Results

Mice treated with ceftriaxone were more colonized than mice treated with cefotaxime after gavage (p-value = 0.008; Kruskal-Wallis test). Ceftriaxone and cefotaxime were both excreted in large quantity in gut lumen but they drove architecture of the gut microbiota in different trajectories. Highest levels of colonization were associated with particular microbiota composition using principal coordinate analysis (PCoA) which were more often achieved in ceftriaxone-treated mice and which were preceded by highest fecal antibiotics concentrations in both cefotaxime or ceftriaxone groups. Using LEfSe, we found that twelve taxa were significantly different between cefotaxime and ceftriaxone-treated mice. Using SplinectomeR, we found that relative abundances of Klebsiella were significantly higher in CRO than in CTX-treated mice (p-value = 0.01).

Conclusion

Ceftriaxone selects a particular microbial community and its substitution for cefotaxime could prevent the selection of extended-spectrum beta-lactamase producing Enterobacteriaceae.

Physicochemical Stability of Cefotaxime Sodium in Polypropylene Syringes at High Concentrations for Intensive Care Units

Background

Cefotaxime sodium is an antibiotic used to treat severe infections such as in intensive care units (ICUs). The recommended dose of cefotaxime sodium can vary from 3 grams (g) to 24 g per day and publications have demonstrated that continuous administration of cefotaxime sodium is the preferred mode of administration. In ICUs, a minimum volume is used for patients requiring fluid restriction, leading to high concentrations of cefotaxime sodium.

The objective was to study the stability of cefotaxime sodium solutions at 83.3 mg/mL and 125 mg/mL, diluted in 0.9 % sodium chloride (0.9 % NaCl) or in 5 % glucose (G5 %), stored in polypropylene syringes, after the preparation and after a 6-hour and a 12-hour storage at 20–25 °C.

Methods

Three syringes for each condition were prepared. At each time of the analysis, three samples for each syringe were prepared and analysed by high performance liquid chromatography (HPLC) coupled to a photodiode array detector. The method was validated according to the International Conference on Harmonisation Q2(R1). Physical stability was evaluated by visual and subvisual inspection (turbidimetry by UV spectrophotometry at 350, 410 and 550 nm as recommended by the European Consensus Conference). pH and osmolality values were measured at each time of the analysis.

Results

For each solvent, cefotaxime sodium solutions at 83.3 mg/mL and 125 mg/mL retained more than 90 % of the initial concentration after 12 hours. During the stability study, pH values decreased slightly, the intensity of the yellow colour increased and values of absorbance increased progressively for each wavelength and each condition. An additional peak with a relative retention of 3.01 was also observed after the forced degradation gradually increased up to 4.01 % and 3.17 % of the total of surface area of the peaks present on the chromatogram after 12 hours in 0.9 % NaCl and in G5 % respectively.

Conclusions

In view of the results and despite the fact that solutions retained more than 90 % of the initial concentration after HPLC analysis, we propose to limit the stability of cefotaxime sodium in 0.9 % NaCl and G5 % at 83.3 and 125 mg/mL at 6 hours. These stability data of highly concentrated solutions provide an additional knowledge to assist ICUs in daily practice. This work also demonstrates that highly concentrated cefotaxime sodium solutions are physically unstable after a 6-hour storage and cannot be administered as a daily infusion.

Delivery of cefotaxime to the brain via intranasal administration

The purpose of this study was to investigate the plausibility of delivery of cefotaxime to the brain via intranasal administration. In vitro permeation studies were carried out using Franz diffusion cells, and the effect of different concentrations of chitosan (0.1% w/v and 0.25% w/v) on drug permeation across the bovine olfactory mucosa was determined. Samples were collected from the receiver compartment at different time points and analyzed using HPLC. The amount of cefotaxime that permeated across the olfactory mucosa when 0.25% w/v of chitosan was used as a permeation enhancer was ~1.5- and ~2-fold higher at the end of the first hour and second hour, respectively, over control (29.56 ± 6.18 µg/cm(2)). There was no significant enhancement in drug permeation when 0.1% w/v chitosan was used as the permeation enhancer. Pharmacokinetic studies were carried out using Sprague-Dawley rats. Cefotaxime solution with 0.25% w/v chitosan (40 mg/kg) was administered intravenously (i.v.) to rats in groups 1 and 3 and intranasally to those in group 2 and 4. The time course of drug in the brain was investigated by performing microdialysis in rats of groups 1 and 2. Blood samples were withdrawn from rats in groups 3 and 4, and cefotaxime in plasma was analyzed using HPLC after extraction with a hydrochloric acid-chloroform:1-pentanol (3:1) and phosphate buffer solvent system. Pharmacokinetic parameters were calculated using the trapezoidal rule. The results imply that the drug levels attained in the brain following i.v. and intranasal administrations were comparable. These results suggest that intranasal administration of cefotaxime could be a potential method of delivering antibacterial agents because of it being noninvasive and patient compliant.

Cefotaxime and desacetylcefotaxime antimicrobial interactions. The clinical relevance of enhanced activity: a review

This presentation reviews 15 years of in vitro, pharmacokinetic, and clinical data concerning the active metabolite of cefotaxime sodium, desacetylcefotaxime. This principle metabolite maintains an antimicrobial activity and spectrum superior to so-called "second-generation" cephalosporins, plus it has an extended serum elimination half-life. Furthermore, it penetrates well into various important body compartments. The metabolite enhances cefotaxime potency by additive or synergistic antimicrobial interactions that can significantly reduce cefotaxime minimum inhibitory concentrations (MICs) among oxacillin-susceptible staphylococci, Streptococcus species including pneumococci resistant to penicillin, anaerobes, enteric bacilli, Pseudomonas aeruginosa, and when tested in human serum, some enterococci. The high activity of cefotaxime alone and the contributions of desacetylcefotaxime to the drug's total antimicrobial value must be considered in reestablishing correct dosing of this "third-generation" cephalosporin. Physicians should use cefotaxime susceptibility tests to direct appropriate, cost-effective dosing and the selection of co-drugs when needed. Moreover, empiric cefotaxime regimen doses should also be reduced for some infections at sites where expected pathogen MICs remain low (< or = 2 micrograms/ml).

Synergistic interaction between ofloxacin and cefotaxime against common clinical pathogens

Antimicrobial synergy resulting from combined antibiotic therapy is often important in the treatment of serious bacterial infections. To investigate the interactions between cefotaxime (CTX), desacetylcefotaxime (DES), and ofloxacin (OFL), 247 recent clinical isolates were tested for in vitro susceptibility to each antibiotic alone by an agar dilution technique and retested with the various antibiotic combinations using a checkerboard protocol. Fractional inhibitory concentrations were calculated for all organisms with all drug combinations. Time kill kinetic studies were performed on selected isolates to examine the bactericidal activity of the various antimicrobial combinations. Of the 110 gram-negative organisms tested, synergy or partial synergy between CTX, DES and OFL was demonstrable for 89 (81%). Included in the study were 70 members of the Enterobacteriaceae family, 20 isolates of Pseudomonas aeruginosa, 10 strains of Acinetobacter baumannii, and 10 isolates of Xanthomonas maltophilia. Additive activity was observed against an additional 13 (11%) isolates. Findings were similar for the 89 gram-positive isolates examined. Organisms tested included methicillin-resistant Staphylococcus aureus (20), methicillin-susceptible Staphylococcus aureus (20), methicillin-resistant Staphylococcus epidermidis (9), methicillin-susceptible S. epidermidis (10), Enterococcus faecalis (10), and Streptococcus pneumoniae (20). Synergy or partial synergy was observed against 81 (91%). Less synergistic activity was detected, however, with members of the Bacteroides fragilis group. Of the 48 organisms tested, synergy or partial synergy was noted for only 27 (57%). Isolates representative of each major group of organisms included in the study were tested to determine whether synergistic bactericidal activity was also demonstrable with the three drugs. Time kill studies supported the checkerboard results.(ABSTRACT TRUNCATED AT 250 WORDS)

The antimicrobial activity of cefotaxime: comparative multinational hospital isolate surveys covering 15 years

The "third-generation" cephalosporins (3GC) have emerged as one of the most significant therapeutic entities in the last 15 years. These 3GC compounds (using cefotaxime as a model) have generally maintained their potency and spectrum of activity against important pathogens. However, the continuing popularity of this class associated with local, regional, or national-level use or abuse has led to efficacy reduction against some organism populations associated with selection of Class I cephalosporinase, stably derepressed mutants predominantly among Citrobacter and Enterobacter spp.; emergence of extended-spectrum beta-lactamase producing Enterobacteriaceae (usually Klebsiella spp.), as well as some isolates mimicking Class I-type resistance patterns; and lastly, altered PBP-mediated resistances among pneumococci, Haemophilus influenzae and pathogenic Neisseria spp. Some of these resistance patterns had been present prior to the clinical introduction of 3GCs and have only significantly threatened their use in the last 5 years. Prudent application of these 3GC drugs should be the goal for this decade as follows: 1) use as monotherapy at appropriate doses and frequencies only for organisms with low potential for mutational events; 2) use combination therapy routinely for organisms such as Citrobacter, Enterobacter, some indole-positive protease and Pseudomonas aeruginosa, to minimize emerging resistance clones; 3) use conservatively in high risk patients to minimize "super-colonization" by emerging problem bacteria (e.g. vancomycin-resistant enterococci, Xanthomonas maltophilia etc.); 4) use only those agents among 3GCs that have documented safety, broad clinical applications to all age groups, acceptable pharmacokinetic features and clear cost-saving potential; and 5) use in prophylaxis (surgical procedure, selective decontamination), should be focused toward single-dose or short-course regimens to reduce total hospital-wide exposure to broad-spectrum beta-lactam drugs.(ABSTRACT TRUNCATED AT 250 WORDS)

Comparative study of pharmacokinetics and serum bactericidal activity of ceftizoxime and cefotaxime

Single 2-g intravenous doses of ceftizoxime (CZX) and cefotaxime (CTX) were given over 30 min to 10 adult volunteers in a crossover manner on two separate occasions. Concentrations of CZX, CTX, and the primary metabolite of CTX, desacetylcefotaxime (dCTX), in serum, suction-induced-blister fluid, and urine were determined by high-pressure liquid chromatography. Pharmacokinetic parameters were estimated by using an extended least-squares modeling program (MKMODEL). CZX exhibited a half-life in serum (2.05 h) longer than that of CTX (1.43 h) but comparable to that of dCTX (2.02 h). The percentage of penetration in blister fluid, estimated by area under the curve ratios, was significantly higher for CZX (164.4%) than for CTX (60.8%). Serum bactericidal activity, determined for volunteer samples at 1, 6, 8, and 12 h after patients were dosed, against clinical isolates of the Bacteroides fragilis group, Enterobacter cloacae, Escherichia coli, Klebsiella pneumoniae, and Morganella morganii were significantly higher for CZX than those for CTX against members of the family Enterobacteriaceae at all times. Serum bactericidal titers against B. fragilis were also higher for CZX than for CTX at 1 h postinfusion. Neither CZX nor CTX exhibited any bactericidal activity at any other time against the B. fragilis group. In conclusion, the serum bactericidal activity of CZX was greater and more-prolonged than that of CTX against tested strains in spite of the in vitro synergistic contribution of dCTX to CTX, equal serum elimination half-lives of dCTX and CZX, and similar antibacterial activity and similar instability under microbiological testing for CZX and CTX.

Synergistic antibacterial interaction of cefotaxime and desacetylcefotaxime

Cefotaxime (CTX) is metabolized in desacetylcefotaxime (dCTX), a less potent compound which shows, however, a higher stability against selected beta-lactamases produced by Gram-negative organisms. The aim of this study was to verify if the antimicrobial activity of CTX against 260 clinical aerobic and anaerobic pathogens isolated in our institution was enhanced by its metabolic derivative dCTX. The combination of CTX and dCTX, assessed by checkerboard titration, was completely or partially synergistic towards 61% of the 220 aerobic organisms tested and against 68% of the 40 Bacteroides strains analyzed. In addition we have investigated, by the time-kill method, the in-vitro interactions against 50 aerobic strains of CTX and dCTX alone and in combination with netilmicin, a drug often employed in severe infections in combination with beta-lactam agents in order to provide effective killing of resistant nosocomial pathogens. Time-kill studies indicated that 36% of the aerobic nosocomial strains were synergistically inhibited by the combination of CTX/dCTX with netilmicin. These results indicate that dCTX makes an important contribution to the clinical efficacy of CTX.

Disposition of cefotaxime and its metabolite, desacetylcefotaxime, in rat: application of a pharmacokinetic-protein binding model

1. The pharmacokinetics and protein binding of cefotaxime and desacetylcefotaxime were studied in rat. 2. After i.v. dosing of cefotaxime (100 mg/kg) the concentration-time profiles of cefotaxime and its metabolite desacetylcefotaxime followed biphasic decays, giving the kinetic parameters for cefotaxime: VTss and AUC of 127 ml/kg and 8.2 mg/min per ml, respectively. The beta-elimination half-life was 17 min with Cls of 13.1 ml/min per kg. The average association constant (K x 10(3) M-1) and total protein binding site concentration (Pt x 10(-3) M) for cefotaxime were 3.87 and 0.68, respectively, with saturation of plasma protein binding occurring at about 30 micrograms/ml. The average free fraction of cefotaxime in plasma (Fp) was 0.48. 3. The metabolite desacetylcefotaxime had a plasma Cmax of 74.4 micrograms/ml (35 min). The respective elimination half-life and AUC were 53 min and 7.2 mg/min per ml. The binding profile, unlike that of cefotaxime, was non-saturable with a K value of 13.90M-1. The Fp of desacetylcefotaxime was 0.89. 4. The concentration-time behaviour of total and free desacetylcefotaxime (i.v. bolus, 50 mg/kg) declined biexponentially with respective VTss and AUC of 125 ml/kg and 19.4 mg/min per ml (total drug), and 192 ml/kg and 13.9 mg/min per ml (free drug). The beta-phase half-life of total and free drug was about 36 min, whereas CLs (ml/min per kg) were 2.7 (total) and 3.7 (free). The binding characteristics were in good agreement with those of the metabolite produced in vivo, with a K value of 8.58 M-1. The Fp value of desacetylcefotaxime in plasma was 0.73.

Pharmacokinetics of cefotaxime and desacetylcefotaxime in the newborn

A study of the pharmacokinetic parameters of cefotaxime (CTX) and desacetylcefotaxime (dCTX) in newborns was conducted; the former is commonly used for neonatal infections. The elimination half life of CTX correlated with gestational age (GA) and postnatal age (PNA). Elimination of dCTX was longer permitting a synergistic or additive effect with CTX against Gram-negative bacteria. CTX is indicated in the treatment of neonatal sepsis because of the increasing resistance of Escherichia coli to ampicillin and its good efficacy against group B streptococcus.

Effectiveness of cefotaxime alone and in combination with desacetylcefotaxime against Bacteroides fragilis

The synergistic activity of the combination cefotaxime-desacetylcefotaxime (CTX/dCTX) was compared to the effectiveness of seven other antimicrobial agents: cefoxitin (CFOX), cefotetan (CTAN), ceftizoxime (CTIZ), chloramphenicol (CLOR), clindamycin (CLIND), metronidazole (METR), and ampicillin-sulbactam (A/S) tested against 100 clinical isolates belonging to the Bacteroides fragilis group. All tests were performed using the NCCLS reference agar-dilution method. The overall susceptibility of these organisms to CTX/dCTX was 84% compared to CFOX at 78% or CTAN at 66%. The other antimicrobials inhibited greater than 90% of these isolates. There was no difference between the susceptibility rates of CTX/dCTX and CTX with the B fragilis (85%) or B. distasonis (75%) strains. Bacteroides thetaiotaomicron showed a 11% greater susceptibility to CTX/dCTX than to CTX. Of the 100 isolates tested, 40% showed either synergy or partial synergistic interactions between CTX and dCTX. Most of the isolates showed indifference (52%), while 8% demonstrated antagonism; a relatively unique finding to date.

A review of cephalosporin metabolism: a lesson to be learned for future chemotherapy

The historical background information concerning the metabolism of cephalosporins and selected other antiinfectives was reviewed as a preface to discussion concerning desacetyl-cefotaxime (dCTX), a metabolite of cefotaxime (CTX) sodium. Cephalothin and cephapirin were metabolized at the 3-position to less active desacetyl forms. However, the parent drugs and their metabolites interact in a favorable manner resulting in dominant additive or synergist inhibition of susceptible bacterial pathogens. Similarly, CTX plus dCTX have been described as being synergist in their activity against greater than 70% of Enterobacteriaceae or staphylococci and greater than 80% of anaerobic bacteria. Antagonism was rare with only two species and of no clinical significance. More recently, reported studies showed enhanced activity of CTX/dCTX against pathogens producing meningitis compared to ceftriaxone and other contemporary therapeutic agents. The dCTX compound was classified as a drug with a potency superior to a "second-generation" cephalosporin and possessed greater beta-lactamase stability against some enzymes compared to CTX. These features may explain low reported rates of superinfections and adverse side-effects, including resistance arising on chemotherapy. Physicians are cautioned to take into account the potential favorable effects of drug metabolites on antimicrobial spectrum, potency and applied pharmacokinetics. In the case of CTX/dCTX, the laboratory results for CTX will always underestimate its value or potency because of the contribution of the metabolite.

Disposition of cefotaxime and desacetyl cefotaxime during continuous ambulatory peritoneal dialysis

The disposition of cefotaxime (CTX) and desacetyl cefotaxime (DAC) was studied in eight noninfected patients on continuous ambulatory peritoneal dialysis. Each patient received a single intravenous (i.v.) infusion and an intraperitoneal (i.p.) instillation of 2 g of CTX. Multiple blood and dialysate samples were collected during the 72-h period after drug administration. The half-life, steady-state volume of distribution, and total body clearance of CTX following i.v. administration were 2.2 +/- 1.0 h (mean +/- standard deviation), 0.17 +/- 0.03 liters/kg, and 81.0 +/- 31.0 ml/min, respectively. No significant differences were observed in these parameters after i.p. administration. The continuous ambulatory peritoneal dialysis clearances of CTX and DAC were 1.82 +/- 0.43 and 2.84 +/- 0.70 ml/min, respectively, after i.v. administration. The bioavailability of CTX after i.p. instillation was 74.6 +/- 21.3%. Peak peritoneal dialysate CTX and DAC concentrations of 264.3 and 25.8 mg/liter, respectively, were observed after i.p. dosing. Administration (i.v.) of 2 g every 12 h or i.p. instillation of 2 g every 24 h may be used for the treatment of i.p. infections with highly susceptible organisms (MIC less than 1.0 microgram/ml).

Population analysis of susceptibility to cefotaxime and desacetyl-cefotaxime in Staphylococcus and Enterobacteriaceae

Population analyses of susceptibility to cefotaxime (CTX) and desacetyl-cefotaxime (DCTX) of strains of Staphylococcus and some genera of Enterobacteriaceae were carried out. DCTX, which is the main metabolite of CTX, has antimicrobial activity. The penicillinase-producing strains of S. aureus and S. epidermidis were homogeneous as regards susceptibility to both agents. CTX was about 4-8 times more active than DCTX. The methicillin-resistant strains contained a sub-population of resistant bacteria with both CTX and DCTX. The frequency of resistant bacteria was 10(-6) - 10(-5). The E. coli strain was homogeneous to both agents. The strains of Enterobacter cloacae and Citrobacter freundii had a sub-population of resistant bacteria with both agents. The frequency of resistant bacteria was 10(-7) - 10(-4.5). In Klebsiella pneumoniae no resistant sub-population was found. CTX was about four times more active than DCTX with the strains of the Enterobacteriaceae. DCTX had no advantage over CTX as regards homogeneity of susceptibility of the populations examined. CTX seems applicable for treatment of infections with E. coli, Klebsiella pneumoniae, and penicillinase-producing, methicillin-susceptible Staphylococcus, but should not be used alone in treatments of infections with Enterobacter cloacae or Citrobacter freundii.

Cefotaxime. A review of its antibacterial activity, pharmacological properties and therapeutic use

SYNOPSIS

Cefotaxime is a new 'third generation' semisynthetic cephalosporin administered intravenously or intramuscularly. It has a broad spectrum of activity against Gram-positive and Gram-negative aerobic and anaerobic bacteria, and is generally more active against Gram-negative bacteria than the 'first' and 'second generation' cephalosporins. Although cefotaxime has some activity against Pseudomonas aeruginosa, on the basis of present evidence it cannot be recommended as sole antibiotic therapy for pseudomonal infections. However, cefotaxime has been effective in treating infections due to other 'difficult' organisms, such as multidrug-resistant Enterobacteriaceae. Like other cephalosporins, cefotaxime is effective in treating patients with complicated urinary tract and lower respiratory tract infections, particularly pneumonia caused by Gram-negative bacilli. High response rates have also been achieved in patients with Gram-negative bacteraemia. Although favourable clinical results have been obtained in patients with infections caused by mixed aerobic/anaerobic organisms (such as peritonitis or soft tissue infections), the relatively low in vitro activity of cefotaxime against Bacteroides fragilis may restrict its usage in situations where this organism is the suspected or proven pathogen. In preliminary studies, males and females treated with a single intramuscular dose of cefotaxime for uncomplicated gonorrhoea caused by penicillinase-producing strains of Neisseria gonorrhoeae responded very favourably. Encouraging results have also been reported in open studies in children including neonates, treated with cefotaxime for meningitis and various other serious infections. In some situations, cefotaxime has been given in combination with another antibiotic such as an aminoglycoside, but the merits of such a combination have not been clearly established. Whether cefotaxime alone is appropriate therapy for conditions previously treated with aminoglycosides (other than pseudomonal infections) also needs additional clarification, but if established as equally effective in such conditions cefotaxime offers potentially important clinical and practical advantages in its apparent lack of serious adverse effects and freedom from the need to undertake drug plasma concentration monitoring.