In vitro comparison of ampicillin-chloramphenicol and ampicillin-cefotaxime against 284 Haemophilus isolates

Could chloramphenicol be used against ESKAPE pathogens? A review of in vitro data in the literature from the 21st century

The widespread use of antibiotics has been associated with the emergence of antimicrobial resistance among bacteria. 'ESKAPE' (Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acintobacter baumannii, Pseudomonas aeruginosa and Enterobacter spp.) pathogens play a major role in the rapidly changing scenario of antimicrobial resistance in the 21st century. Chloramphenicol is a broad spectrum antibiotic that was abandoned in developed countries due to its association with fatal aplastic anemia. However, it is still widely used in the developing world. In light of the emerging problem of multi-drug resistant pathogens, its role should be reassessed. Our paper reviews in vitro data on the activity of chloramphenicol against ESKAPE pathogens. Susceptibility patterns for Gram-positives were good, although less favorable for Gram-negatives. However, in combination with colistin, chloramphenicol was found to have synergistic activity. The risk-benefit related to chloramphenicol toxicity has not been analyzed. Therefore, extra precautions should be taken when prescribing this agent.

Modified time-kill assay against multidrug-resistant Enterococcus faecium with novel antimicrobial combinations

This study used a modified time-kill assay to compare the in-vitro activity of chloramphenicol and quinopristin/dalfopristin combined with vancomycin, ampicillin or gentamicin against multidrug-resistant Enterococcus faecium. The assay uses standardized time-kill methods with the following modifications: centrifugation of the test tubes at 1-2 h intervals, removal of supernatant and resuspension of bacteria in media containing antibiotic concentrations corresponding to simulated steady-state serum concentrations. None of the agents, alone or in combination, produced bactericidal or synergic activity. The modified time-kill assay more closely simulates in-vivo conditions and may provide a better qualitative assay to determine the interaction between antimicrobial agents and bacteria.

In vitro activity of chloramphenicol alone and in combination with vancomycin, ampicillin, or RP 59500 (quinupristin/dalfopristin) against vancomycin-resistant enterococci

Using a checkerboard assay, ampicillin, vancomycin, and RP 59500, each in combination with chloramphenicol, were tested for synergy against 23 isolates of vancomycin-resistant enterococci. Additive effects were seen in 62.5% of the isolates when exposed to chloramphenicol plus RP 59500. Additive effects were observed in 20% and 15% of isolates with chloramphenicol plus vancomycin or ampicillin, respectively. No antagonism was noted.

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).

Cefotaxime. An update of its pharmacology and therapeutic use

Cefotaxime was the first 'third generation' cephalosporin to be marketed and is administered intramuscularly or intravenously. Similar to other agents of this class, it has a broad spectrum of in vitro activity, particularly against Enterobacteriaceae, including beta-lactamase-producing strains. Cefotaxime forms a metabolite, desacetylcefotaxime, which is antibacterially effective against many bacteria per se and acts additively or synergistically with cefotaxime against many strains. Since the first review of cefotaxime in the Journal, further studies have confirmed its value in the treatment of various infections: complicated urinary tract infections, lower respiratory tract infections, bacteraemia, meningitis, uncomplicated gonorrhoea, infections of skin and soft tissue and of bone and joints, and obstetric and gynaecological infections. Cefotaxime is effective as an empirical treatment of suspected infection due to susceptible organisms in immunocompromised patients and is of proven efficacy in serious, life-threatening infections in general. Cefotaxime reduces the incidence of postsurgical infection but the role of third generation cephalosporins in prophylaxis remains to be determined. The indications for which cefotaxime and other 'third generation' cephalosporins would be considered the most appropriate therapy remain largely dependent upon such factors as varied as cost, local medical custom, decisions of regulatory agencies and geographical patterns of bacterial resistance. Cefotaxime nevertheless represents a valuable 'third generation' cephalosporin of great clinical value in certain infectious conditions, in particular those which are serious and life-threatening and where resistance to therapies is creating a clinical problem.

Antibiotic therapy of meningitis caused by ampicillin-resistant Haemophilus influenzae in Denmark and Greenland 1981 to 1987

A survey was performed in Denmark and Greenland in order to determine whether the current recommendation of ampicillin (400 mg/kg/day) for initial treatment of purulent meningitis is appropriate. Data obtained 1981-1987 in an ongoing nationwide programme for surveillance of ampicillin-resistant Haemophilus species was analysed, and patient records of 21 cases of meningitis caused by ampicillin-resistant Haemophilus influenzae strains (17 in Denmark, 4 in Greenland) reported in the period 1981-1987 were reviewed. In Denmark the overall rate of ampicillin-resistant Haemophilus influenzae was estimated to be approximately 2% for the study period, and the average rate of resistant isolates from spinal fluid was 5.2% (range 0-12.3%). The incidence of meningitis caused by ampicillin-resistant Haemophilus influenzae strains remained low in the Danish population (around 0.05/100,000/year) except for a peak in 1985. The overall mortality rate of Haemophilus influenzae meningitis for the study period was 2.4%, which was the same as before 1980. In Greenland the actual number of cases of meningitis caused by ampicillin-resistant Haemophilus influenzae was small, but the incidence was at least 40 to 80 times higher than in Denmark with a high mortality rate (50%). These observations prompted revision of the antibiotic regimen in Greenland, whereas the regimen was considered appropriate in Denmark.

Chloramphenicol and tetracyclines

Tetracyclines have a broad range of clinical usefulness because of their broad antimicrobial spectrum of activity. For most routine gram positive and gram negative infections, alternative agents are available, but for Chlamydiae, Rickettsiae, Brucella, and Borrelia they still remain agents of choice. To some extent, gastrointestinal intolerance and inability to use these agents in patients with renal dysfunction have been overcome by the availability of doxycycline. Phototoxicity is a problem with this agent, however. Tetracycline is still useful as a sclerogenic agent for malignant effusions, and demeclocycline often is an agent of choice in therapy of inappropriate antidiuretic hormone secretion.