In vitro activity of cefmetazole, cefotetan, amoxicillin-clavulanic acid, and other antimicrobial agents against anaerobic bacteria from endometrial cultures of women with pelvic infections

Oral and intramuscular treatment options for early postpartum endometritis in low-resource settings: a systematic review

OBJECTIVE

To suggest options for oral and intramuscular antibiotic treatment of early postpartum endometritis in low-resource community settings where intravenous antibiotics are unavailable.

DATA SOURCES

Studies were identified through MEDLINE from inception through December 2014. Search terms included [("anti-bacterial agents [MeSH]" or "anti-infective agents [MeSH]") and ("endometritis [MeSH]" or "puerperal infection [MeSH]")]. A second search using the terms [("endometritis or endomyometritis or puerperal infection) and ("antibiotics or antimicrobials or anti-bacterial agents or anti-infective agents)"] was also used. Additionally, all references from selected articles were reviewed, a hand-search of a subject matter expert library was conducted, and a search of ClinicalTrials.gov was performed.

METHODS OF STUDY SELECTION

We conducted a systematic review of the literature in two phases. Phase I provides a summary of clinical cure data from prospective studies of oral and intramuscular antimicrobial regimens as well as summarizes evidence from trials of intravenous antimicrobials. Phase II is a quantitative analysis of pathogens from intrauterine postpartum endometritis samples. Based on these results, and with consideration of existing recommendations for antibiotic use during breastfeeding, we suggest oral and intramuscular antimicrobial options for the treatment of early postpartum endometritis after vaginal delivery in low-resource settings.

TABULATION, INTEGRATION, AND RESULTS

Reports involving oral or intramuscular antimicrobial treatment of postpartum endometritis are rare and of generally poor quality. Antimicrobial trials of postpartum endometritis treatment and intrauterine microbiology studies suggest five antimicrobial regimens may be effective: oral clindamycin plus intramuscular gentamicin, oral amoxicillin-clavulanate, intramuscular cefotetan, intramuscular meropenem or imipenem-cilastatin, and oral amoxicillin in combination with oral metronidazole.

CONCLUSION

This review provides suggestions for oral, intramuscular, and combined antimicrobial regimens that may warrant additional study. Experimental trials should consider clinical effectiveness, safety and side effects profiles, and feasibility of community-based treatment.

Determination of unbound cefmetazole in rat blood by on-line microdialysis and microbore liquid chromatography: a pharmacokinetic study

A specific and sensitive microbore liquid chromatographic method for the determination of unbound cefmetazole in rat blood was developed. A microdialysis probe was inserted into the jugular vein/right atrium of a Sprague-Dawley rat. Cefmetazole (10 mg/kg, i.v.) was then administered via the femoral vein. Dialysates were automatically injected into a liquid chromatographic system via an on-line injector. Isocratic elution of cefmetazole was achieved by LC-UV within 10 min. Intra- and inter-assay accuracy and precision of the assay were < or = 10%. The detection limit of cefmetazole was 20 ng/ml. Pharmacokinetic analysis of results indicated that unbound cefmetazole levels in rats best fit a biexponential decay model.

Carbapenems and monobactams: imipenem, meropenem, and aztreonam

Imipenem and meropenem, members of the carbapenem class of beta-lactam antibiotics, are among the most broadly active antibiotics available for systemic use in humans. They are active against streptococci, methicillin-sensitive staphylococci, Neisseria, Haemophilus, anaerobes, and the common aerobic gram-negative nosocomial pathogens including Pseudomonas. Resistance to imipenem and meropenem may emerge during treatment of P. aeruginosa infections, as has occurred with other beta-lactam agents; Stenotrophomonas maltophilia is typically resistant to both imipenem and meropenem. Like the penicillins, the carbapenems have inhibitory activity against enterococci. In general, the in vitro activity of imipenem against aerobic gram-positive cocci is somewhat greater than that of meropenem, whereas the in vitro activity of meropenem against aerobic gram-negative bacilli is somewhat greater than that of imipenem. Daily dosages may range from 0.5 to 1 g every 6 to 8 hours in patients with normal renal function; the daily dose of meropenem, however, can be safely increased to 6 g. Infusion-related nausea and vomiting, as well as seizures, which have been the main toxic effects of imipenem, occur no more frequently during treatment with meropenem than during treatment with other beta-lactam antibiotics. The carbapenems should be considered for treatment of mixed bacterial infections and aerobic gram-negative bacteria that are not susceptible to other beta-lactam agents. Indiscriminate use of these drugs will promote resistance to them. Aztreonam, the first marketed monobactam, has activity against most aerobic gram-negative bacilli including P. aeruginosa. The drug is not nephrotoxic, is weakly immunogenic, and has not been associated with disorders of coagulation. Aztreonam may be administered intramuscularly or intravenously; the primary route of elimination is urinary excretion. In patients with normal renal function, the recommended dosing interval is every 8 hours. Patients with renal impairment require dosage adjustment. Aztreonam is used primarily as an alternative to aminoglycosides and for the treatment of aerobic gram-negative infections. It is often used in combination therapy for mixed aerobic and anaerobic infections. Approved indications for its use include infections of the urinary tract or lower respiratory tract, intra-abdominal and gynecologic infections, septicemia, and cutaneous infections caused by susceptible organisms. Concurrent initial therapy with other antimicrobial agents is recommended before the causative organism has been determined in patients who are seriously ill or at risk for gram-positive or anaerobic infection.

A review of the microbiology of amoxycillin/clavulanic acid over the 15 year period 1978-1993

A review of the published literature over the period 1978-1993 was undertaken to assess any changes in the prevalence of beta-lactamase-producing bacterial pathogens and also any changes in the susceptibility in these pathogens to amoxycillin/clavulanate. The review has involved the examination of over 1500 publications. The review shows that in general there has been an increase in the frequency of beta-lactamase-producing pathogens resistant to ampicillin and amoxycillin but there is no evidence for any significant increase in resistance to amoxycillin/clavulanate over the period of the review.

beta-Lactamase production and susceptibility of US and European anaerobic gram-negative bacilli to beta-lactams and other agents

The susceptibility of 1,476 US and European strains of anaerobic gram-negative bacilli to amoxicillin, amoxicillin/clavulanate, ticarcillin, ticarcillin/clavulanate, cefoxitin, imipenem and metronidazole was determined. All of the Bacteroides fragilis group and 51% of the non-Bacteroides fragilis group were beta-lactamase positive. Amongst the non-Bacteroides fragilis group, beta-lactamase positivity rates were higher for US strains (58%) than for European strains (39%). All strains were susceptible to imipenem and metronidazole. MIC90s of amoxicillin and ticarcillin for all beta-lactamase negative strains were 0.5 and 2 micrograms/ml, respectively. The addition of clavulanate reduced the MIC90s of amoxicillin (> or = 256 micrograms/ml) and ticarcillin (> or = 64 micrograms/ml) to 16 and 8 micrograms/ml, respectively, for the Bacteroides fragilis group, and to 4 micrograms/ml for both agents for the non-Bacteroides fragilis beta-lactamase producing group. Twenty-nine cefoxitin-resistant strains were found, mainly in the Bacteroides fragilis group, while 95 beta-lactamase producing strains (predominantly Bacteroides fragilis group and fusobacteria) did not show synergy between beta-lactams and clavulanate. Of the newe agents tested, meropenem and piperacillin-tazobactam were the most active (100% of strains susceptible), followed by amoxicillin-BRL 42715 (99% of strains susceptible); 94 to 98% of the strains were susceptible to cefoperazone-sulbactam, tosufloxacin, temafloxacin and clindamycin. Only 73% of the strains were susceptible to cefotetan, compared to 91% to cefoxitin; 88% of the strains were susceptible to trospectomycin. Overall, all of the beta-lactam/beta-lactamase inhibitor combinations, imipenem, meropenem, cefoxitin, tosufloxacin, temafloxacin and clindamycin had good activity against beta-lactamase producing strains, while all agents tested had good activity against beta-lactamase negative strains.

Resistance of Peptostreptococcus spp. to macrolides and lincosamides: inducible and constitutive phenotypes

The activities of erythromycin and clindamycin against 350 Peptostreptococcus strains were studied during a 5-year period (1986 to 1991). In 5.1% of the Peptostreptococcus strains, which presented dissociated resistance (clindamycin MIC, less than or equal to 1 microgram/ml; erythromycin MIC, greater than 8 micrograms/ml), evidence of inducible macrolide-lincosamide resistance was shown. A total of 17.7% of the strains presented a constitutive phenotype; the clindamycin and erythromycin MICs for these strains were greater than 8 micrograms/ml.

Imipenem

Imipenem is the first of a new class of beta-lactam antibiotics, the carbapenems, to be released for clinical use. It has the broadest antibacterial activity of all antibiotics available for systemic use in humans. It is active against streptococci, methicillin-sensitive staphylococci, Neisseria, Haemophilus, anaerobes, and the common aerobic gram-negative nosocomial pathogens including Pseudomonas. Resistance to imipenem may emerge during treatment of P. aeruginosa infections, as has occurred with other beta-lactam agents; P. maltophilia and P. cepacia are typically resistant to it. Like the penicillins, imipenem has inhibitory activity against enterococci. Daily doses may range from 500 mg to 1 g, every 6 to 8 hours, in patients with normal renal function. The principal toxic effects have been nausea and vomiting, which occur during intravenous infusion, and seizures, which develop in 1 to 3% of treated patients and are likely to occur in the setting of renal insufficiency and underlying disease of the central nervous system. Imipenem should be considered for treatment of mixed bacterial infections and treatment of resistant aerobic gram-negative bacteria that are not susceptible to other beta-lactam agents. In addition to provoking unnecessary toxicity, indiscriminate use of this agent will promote dissemination of resistance against it.

Susceptibilities of 394 Bacteroides fragilis, non-B. fragilis group Bacteroides species, and Fusobacterium species to newer antimicrobial agents

The susceptibilities of 374 selected beta-lactamase-producing gram-negative anaerobes (including 22 cefoxitin-resistant strains and 36 strains refractory to the enhancing effect of beta-lactamase inhibitors) and 20 beta-lactamase-negative strains were tested by agar dilution against selected new agents. The organisms included 217 Bacteroides fragilis group strains, 137 non-B. fragilis group Bacteroides spp., and 40 fusobacteria. All strains were susceptible to piperacillin-tazobactam, imipenem, and meropenem. For the B. fragilis group, 96% were susceptible to ampicillin-sulbactam, 95% were susceptible to amoxicillin-clavulanate and cefoperazone-sulbactam, 94% were susceptible to tosufloxacin, 91% were susceptible to cefoxitin, 88% were susceptible to trospectomycin, and 73% were susceptible to cefotetan. For the beta-lactamase-positive non-B. fragilis group Bacteroides spp., greater than or equal to 94% were susceptible to cefoxitin, amoxicillin-clavulanate, ampicillin-sulbactam, cefoperazone-sulbactam, and trospectomycin, 90% were susceptible to cefotetan, and 85% were susceptible to tosufloxacin (the most resistant strains were B. bivius and B. disiens). For the beta-lactamase-positive fusobacteria, greater than or equal to 97% were susceptible to amoxicillin-clavulanate, ampicillin-sulbactam, cefoperazone-sulbactam, trospectomycin, and cefoxitin, 90% were susceptible to cefotetan, and 89% were susceptible to tosufloxacin. All agents showed excellent activity against beta-lactamase-negative strains (for trospectomycin, 95% were susceptible; for all other drugs, 100% were susceptible). Overall, both carbapenems and piperacillin-tazobactam were most active. Amoxicillin-clavulanate, ampicillin-sulbactam, and cefoperazone-sulbactam lacked activity against some cefoxitin-resistant B. fragilis group strains but had excellent activity against other organisms. Tosufloxacin, a new quinolone, had very good activity against B. fragilis group strains (94% susceptible), good activity against other beta-lactamase-positive strains (less than or equal 85% susceptible), and excellent activity against beta-lactamase-negative strains (100% susceptible; MIC for 90% of strains, 0.5 microgram/ml). Trospectomycin was active against >90% of all strains except for B. fragilis group strains (88% susceptible; MIC for 90% of strains, 32 microgram/ml). Clinical studies are required to delineate the role of newer agents in the therapy of anaerobic infections.

Pharmacokinetics and dose proportionality of cefmetazole in healthy young and elderly volunteers

The pharmacokinetics and dose proportionality of cefmetazole were studied in 24 healthy volunteers (12 young and 12 elderly). Each volunteer received single 0.5-, 1-, and 2-g doses of cefmetazole administered intravenously over 5 min according to a three-way crossover design. Serial plasma and urine samples were collected over a 24-h period following dosing and assayed for cefmetazole by a high-performance liquid chromatography method. Results of the dose proportionality portion of the study indicated that cefmetazole pharmacokinetics are linear and proportional with dose in both age groups. Comparisons of pharmacokinetic parameters between the young and elderly groups indicated that the systemic clearance was significantly lower in elderly than in young volunteers (92.4 versus 112 ml/min). Additionally, creatinine clearance was significantly lower in elderly (74.1 ml/min) than in young (92.9 ml/min) subjects. No significant differences between age groups were observed for volume of distribution, urinary recovery, terminal half-life, nonrenal clearance, or renal clearance, although half-life was slightly prolonged in elderly volunteers relative to that in young volunteers (1.54 versus 1.34 h), and renal clearance was slightly lower in elderly than in young volunteers (83.7 versus 96.1 ml/min). Both systemic and renal clearance were significantly correlated with creatinine clearance. These results indicate that the observed age-related differences in the pharmacokinetics of cefmetazole are most likely due to differences in renal function between the two age groups. The small reduction in cefmetazole elimination in the elderly would not warrant dose adjustment in this population.

Beta-lactamase production and susceptibilities to amoxicillin, amoxicillin-clavulanate, ticarcillin, ticarcillin-clavulanate, cefoxitin, imipenem, and metronidazole of 320 non-Bacteroides fragilis Bacteroides isolates and 129 fusobacteria from 28 U.S. centers

beta-Lactamase production (nitrocefin disk method) and agar dilution susceptibility of amoxicillin, amoxicillin-clavulanate, ticarcillin, ticarcillin-clavulanate, cefoxitin, imipenem, and metronidazole were determined for 320 Bacteroides species (not Bacteroides fragilis group) and 129 fusobacteria from 28 U.S. centers. Overall, 64.7% of Bacteroides species and 41.1% of fusobacteria were beta-lactamase positive. Among the Bacteroides species, positivity rates were highest for B. bivius (85.0%), followed by B. splanchnicus (83.3%), B. eggerthii (77.8%), and B. oralis (77.1%); 54.5% of black-pigmented Bacteroides species were beta-lactamase positive. Among the fusobacteria, Fusobacterium mortiferum showed the highest rate of beta-lactamase positivity (76.9%). MICs of amoxicillin (128 micrograms/ml) and ticarcillin (64 micrograms/ml) for 90% of all beta-lactamase-positive strains were reduced to 4 and 2 micrograms/ml, respectively, with the addition of clavulanate. MICs of amoxicillin and ticarcillin for 90% of all beta-lactamase-negative strains were 1 and 4 micrograms/ml, respectively, and greater than or equal to 98.4% of the strains were susceptible to the beta-lactams tested. Of the beta-lactamase-producing strains, 45.9% were susceptible to amoxicillin at less than or equal to 4 micrograms/ml and 93.4% were susceptible to ticarcillin at less than or equal to 64 micrograms/ml; the addition of clavulanate raised the rates to 90.4 and 100%, respectively. All strains were susceptible to cefoxitin, imipenem, and metronidazole. The activity of amoxicillin against 29 beta-lactamase-producing strains (10 Bacteroides species and 19 fusobacteria) was not enhanced by the addition of clavulanate; however, 82.7% of these strains were susceptible to amoxicillin, and all were susceptible to ticarcillin. Although beta-lactamase positivity is on the increase in non-B. fragilis group Bacteroides species and fusobacteria, amoxicillin-clavulanate, ticarcillin, cefoxitin, imipenem, and metronidazole should be suitable for the treatment of infections with these strains. The addition of clavulanate does not appreciably improve the efficacy of ticarcillin against these organisms.

Evaluation of the activity of four antimicrobial agents using an in vitro rapid micromethod against oral streptococci and various bacterial strains implicated in periodontitis

The activity of various antibacterial agents (amoxicillin, josamycin, doxycycline and metronidazole) was established in vitro using a rapid micromethod. The activity of these agents, which are widely used in oral medicine, was evaluated against microorganisms responsible for periodontitis and bucco-dental infections. Their action against alpha-hemolytic streptococci (including pneumococci) which make up the majority of the indigenous oral flora was also tested. Amoxicillin was found to be effective against all the strains tested. Doxycycline was active against periodontal bacteria, but not against 50% of the streptococcal flora. Josamycin was found to be effective against streptococci, but appeared without effect on Eikenella corrodens and Actinobacillus actinomycetemcomitans. Metronidazole, inactive against streptococci, displayed greater activity towards the strict anaerobes. The use of these antibiotics for the treatment of bucco-dental infections, especially periodontitis, is discussed. For periodontitis and periodontal suppurations, antimicrobial agents present a valuable adjunct to local treatments such as scaling or rootplaning. This may prevent more serious infections such as endocarditis that can develop after tooth extraction.

Susceptibility of Bacteroides non-fragilis and fusobacteria to amoxicillin, amoxicillin/clavulanate, ticarcillin, ticarcillin/clavulanate, cefoxitin, imipenem and metronidazole

The susceptibility of 234 Bacteroides non-fragilis strains and 56 fusobacteria from 12 European centers to amoxicillin, amoxicillin/clavulanate, ticarcillin, ticarcillin/clavulanate, cefoxitin, imipenem and metronidazole was tested and related to beta-lactamase production. Beta-lactamase production was detected in 42.3 % of the Bacteroides strains and 26.8% of the fusobacteria. The MIC90 of amoxicillin for beta-lactamase-negative strains was 0.5 microgram/ml and the MIC90 of ticarcillin 2.0 micrograms/ml. In the case of beta-lactamase-positive strains the MIC90 of amoxicillin (32 micrograms/ml) and ticarcillin (16 micrograms/ml) dropped to less than or equal to 1.0 microgram/ml upon addition of clavulanate; 65.8% of these strains were susceptible to amoxicillin and 98.2% to ticarcillin, but all were susceptible when clavulanate was added. All strains were susceptible to imipenem and metronidazole, and 99.3% to cefoxitin.

Disposition of cefmetazole in healthy volunteers and patients with impaired renal function

The disposition of cefmetazole was studied in 25 subjects with various degrees of renal function after a 1,000-mg, constant-rate, 30-min intravenous infusion of cefmetazole sodium. In six subjects with creatinine clearance (CLCR) of greater than 90 ml/min per 1.73 m2 (group 1), the terminal elimination half-life (t1/2 beta) was 1.31 +/- 0.54 h (mean +/- standard deviation), cefmetazole total body clearance (CLP) was 132.8 +/- 25.1 ml/min per 1.73 m2, and volume of distribution at steady state was 0.165 +/- 0.025 liter/kg. The fraction of dose excreted unchanged in the urine was 84.0% +/- 26.1%. Subjects with CLCRS of 40 to 69 (group 2, n = 6) and 10 to 39 (group 3, n = 6) ml/min per 1.73 m2 demonstrated prolongation of the t1/2 beta (3.62 +/- 1.06 and 5.93 +/- 1.81 h, respectively) and significant reductions in cefmetazole CLP (52.8 +/- 14.3 and 30.2 +/- 10.2 ml/min per 1.73 m2, respectively), compared with group 1. In seven subjects on chronic hemodialysis (group 4) studied during an interdialytic period, the cefmetazole t1/2 beta was increased to 24.10 +/- 8.12 h and the CLP was reduced to 6.8 +/- 2.1 ml/min per 1.73 m2. Cefmetazole CLP correlated positively with CLCR (r = 0.951, P less than 0.001): CLP = (1.181 . CLCR) -- 0.287. The disposition of cefmetazole was also assessed in six group 4 subjects during an intradialytic period. The t1/2 beta during hemodialysis (2.09 +/- 0.69 h) was significantly shorter than that observed during the interdialytic period. The hemodialysis clearance of cefmetazole was 86.1 +/- 20.1 ml/min, and the fraction of cefmetazole removed during hemodialysis was 59.8% +/- 5.9%. It is recommended that patients with renal insufficiency received standard doses of cefmetazole at extended intervals and patients on maintenance hemodialysis received standard doses after hemodialysis.

Cefmetazole (CS-1170), a "new" cephamycin with a decade of clinical experience

In vitro and in vivo study results were reviewed from cefmetazole, a "new" parenteral cephamycin. Cefmetazole's spectrum of activity was comparable to that of second-generation cephalosporins, which includes clinical coverage of many Enterobacteriaceae, Staphylococcus spp., streptococci, Haemophilus spp., pathogenic Neisseria, Branhamella catarrhalis, and anaerobic bacteria. Cefmetazole was generally more potent (two- to eightfold) than cefoxitin against organisms within their spectrums and was particularly active for staphylococci (MIC90, 2.0 micrograms/ml). Methicillin-resistant S. aureus strains were more susceptible to cefmetazole alone or in combination (fosfomycin) than any other cephamycin. Cefmetazole has demonstrated excellent stability to aerobic and anaerobic organism-produced beta-lactamases. It also inhibits Type I cephalosporinases and, uniquely, some other cephalosporinases produced by the Bacteroides. This superior stability, enzyme interaction, and better penetration into bacterial cells results in a sustained bactericidal effect and a capacity for more infrequent dosing. The cefmetazole serum elimination half-life was 1.5 hr, also justifying use at greater than or equal to 8-hr intervals. Clinical trials in the United States and Japan demonstrated an acceptably high cefmetazole infection cure rate (88% to 100%), especially in direct comparative studies with cefoxitin. Cefmetazole was also proven very effective in minimizing infectious wound morbidity (prophylaxis) using 2 g single- or multidose regimens. Adverse drug reactions were usually minor; in the Japanese surveillance trial (118,318 patients) the rate was only 2.2% (8.8% in United States). Cefmetazole has been extensively and safely used in Japan since 1980.