Comparative study of piperacillin versus cefoxitin in the treatment of obstetric and gynecologic infections

Chorioamnionitis and endometritis

Chorioamnionitis complicates 1% to 2% of all pregnancies and may affect 10% of women with certain risk factors. Intraamnionic infection may result in devastating morbidity for both the fetus and the mother. Also, chorioamnionitis is associated with higher cesarean section rates. As demonstrated earlier, endometritis is a common complication of cesarean delivery alone. Nevertheless, antibiotic prophylaxis has been shown to reduce postpartum morbidity. In the face of chorioamnionitis and a cesarean delivery, the risk of developing endometritis increases exponentially. However, if appropriate antibiotic therapy is instituted at the time of diagnosis, fetal and maternal outcomes improve dramatically. Similar to chorioamnionitis, endometritis is usually polymicrobial in nature. The preponderance of the organisms isolated are anaerobic. Established risk factors include operative delivery, prolonged ruptured fetal membranes, and prolonged labor. The diagnosis is based primarily on clinical examination with fever and the exclusion of other sources of extrapelvic infection. Once the diagnosis is established, appropriate empiric antibiotics are instituted. Antibiotic therapy should be continued until the patient is afebrile and asymptomatic for 24 to 36 hours. Over the past 20 years, the use of single-agent therapy in these serious infections has been shown to be safe as well as effective. Once successful therapy is completed, the patient is discharged home with no oral antibiotics.

Cefoxitin in the prevention and treatment of infections

A review of the literature indicates that cefoxitin is an effective single-agent therapy for community-acquired intra-abdominal infections, pelvic infections, and surgical prophylaxis. Hospital-acquired intra-abdominal infections may require the addition of an aminoglycoside.

Treatment of acute salpingitis with sulbactam/ampicillin

The combination of sulbactam/ampicillin was compared to cefoxitin for the treatment of acute salpingitis in 40 women divided into two groups of 20 women each. There were 11 patients in each group who were given doxycycline because of evidence of chlamydial infection. All patients were diagnosed by laparoscopic examination and evaluated by the same procedure 7-12 weeks later. At the second laparoscopy, only 1 of the 20 patients (5%) treated with sulbactam/ampicillin had severe adhesions, while 6 of the 20 patients (40%) treated with cefoxitin had severe adhesions. Tubal patency was without obstruction in 14 patients (70%) given the combination treatment and in 12 patients (60%) given cefoxitin. Side effects were essentially absent in both groups.

Multicenter clinical trials comparing cefotetan with moxalactam or cefoxitin as therapy for obstetric and gynecologic infections

The clinical efficacy and safety of cefotetan was assessed in two multicenter clinical trials involving 335 evaluable patients hospitalized with obstetric and gynecologic infections. In Study I, cefotetan was compared with moxalactam and in Study II, cefotetan was compared with cefoxitin. The clinical response rate in Study I was 67 of 70 patients for cefotetan (96 percent) and 33 of 34 patients (97 percent) for moxalactam. In Study II, the clinical response rate was 138 of 147 patients in the cefotetan group (94 percent) and 76 of 84 patients in the cefoxitin group (91 percent). For the patients with bacteriologic response data, 196 of 205 cefotetan patients (96 percent), 23 of 24 moxalactam patients (96 percent), and 70 of 75 cefoxitin patients (93 percent) had a satisfactory bacteriologic response. Cefotetan was well tolerated and produced no major adverse reactions. The mean amount of cefotetan given was lower than that of moxalactam or cefoxitin.

Multicenter comparison of cefotetan and cefoxitin in the treatment of acute obstetric and gynecologic infections

Two hundred eighty-seven women were treated in a multicenter, randomized, comparative study to compare the safety and efficacy of cefotetan every 12 hours with that of cefoxitin every 6 or 8 hours in the treatment of acute obstetric and gynecologic pelvic infections. The most frequent primary diagnoses in both groups were endometritis and pelvic inflammatory disease; 24 of these patients were also bacteremic. The mean duration of treatment was 5.2 and 5.4 days for the cefotetan and cefoxitin groups, respectively, and the total doses administered were 18.1 and 32.1 gm, respectively. The rate of clinical failure for the cefotetan group was 8.5% and 12.2% for the cefoxitin group. Laboratory and clinical adverse reactions were infrequent and none was serious; both antimicrobials were well tolerated. These results suggest the administration of cefotetan provided adequate clinical and bacteriologic effectiveness in the treatment of hospital- and community-acquired, polymicrobial obstetric and gynecologic pelvic infections.

Comparative in vitro beta-lactam activity against aerobic and anaerobic surgical isolates

The comparative in vitro activity of cefoxitin, piperacillin, cefotetan, and ceftizoxime was compared against 843 surgical microbial isolates. All compounds exhibited excellent activity against the streptococcal isolates. Antimicrobial activity was poor for Staphylococcus aureus and S. epidermidis. Cefotetan activity against the Enterobacteriaceae was comparable to ceftizoxime (greater than 95% susceptible). Resistance rates of 0, 1, 5, and 2% were observed with cefoxitin, piperacillin, cefotetan, and ceftizoxime against the anaerobic cocci and anaerobic gram-positive non-spore-forming rods. Ninety-six and ninety-nine percent of the clostridial strains were susceptible to cefotetan and piperacillin, respectively. Piperacillin, cefotetan, and ceftizoxime exhibited similar activity against Bacteroides fragilis (resistance less than 10%). Cefotetan and cefoxitin exhibited poor activity against Bacteroides distasonis, B. ovatus, and B. thetaiotaomicron. Antimicrobial activities were comparable for the four drugs against other Bacteroides and Fusobacterium species. The results demonstrate that all four compounds exhibited broad antimicrobial activity against facultative and obligate anaerobic surgical isolates from intraabdominal and soft tissue infections.

Single-agent therapy for women with acute polymicrobial pelvic infections

Pathogens that cause acute polymicrobial female pelvic infections usually do not differ from those that compose the normal flora of the lower reproductive tract. Accurate identification of these bacteria is difficult because cultures obtained via the lower tract can easily be contaminated. Although use of a double-lumen catheter-protected brush culture cannot completely eliminate the risk of contamination, it is the least invasive method for obtaining culture material from the upper reproductive tract. Compounding the problem of accurately identifying pathogens that cause acute upper tract infections is the fact that bacteria appear to be present in the upper tracts of asymptomatic women with normal examinations. Because of these problems and because of the polymicrobial nature of these infections, empiric therapy frequently includes more than one antimicrobial agent. Newer, semisynthetic penicillins and cephalosporins have expanded spectrums of in vitro activity against most of the bacteria frequently recovered from pelvic infection sites. Comparative clinical trials have shown these agents to be as effective when used alone as is combination therapy. With few exceptions, empiric monotherapy with one of these newer antimicrobials will be curative for women with acute upper tract infection, will have less potential toxicity, will require less space, materials, and manpower to administer, and will be less expensive.

Treatment and prevention of female pelvic infection: the quest for single-agent therapy

The advantages of a single-agent regimen for prevention or treatment of female pelvic infections are outlined, and the characteristics of an "ideal" single agent are described. Indications for antimicrobial use in obstetrics and gynecology as well as the pathogens most likely to cause infection are reviewed. Empirical treatment regimens are assessed not only for efficacy but also for safety, simplicity, cost, and potential for inducing bacterial resistance. Piperacillin, as an example of an antimicrobial that may be appropriate for single-agent use in female pelvic infections, is evaluated in depth.

Single-dose cephalosporin for prevention of major pelvic infection after vaginal hysterectomy: cefazolin versus cefoxitin versus cefotaxime

Antimicrobial overutilization accelerates the development of bacterial resistance. A prospective, randomized, blinded clinical trial of vaginal hysterectomy prophylaxis was designed to compare the efficacy, safety, and costs of cefazolin with those of cefoxitin and cefotaxime. Sixteen women (7.5%) developed febrile morbidity only, 10 (4.7%) developed major pelvic infection requiring parenteral antimicrobial therapy, and neither clinical nor laboratory adverse reactions of significance were observed. Anemia, diabetes, and additional surgical procedures were associated with a significantly increased incidence of postoperative infection; no regimen was more protective for women with or without these risk factors. Infections almost doubled hospital stay and the charges for health care. Diagnosis-related group reimbursement would have been more than $1,300 less than the mean hospital charge for women who developed infection. Utilizing cefazolin for prophylaxis and reserving cefoxitin and cefotaxime for therapy is cost and antimicrobial efficient.

A review of the role of beta-lactamase-producing bacteria in obstetric-gynecologic infections

beta-Lactam antibiotics are the most commonly used antibiotics in obstetrics and gynecology. However, they are susceptible to inactivation when attacked by beta-lactamase, an enzyme produced by many bacterial species. During the past three decades, numerous penicillins and cephalosporins have been made with a stable beta-lactam ring that resists enzyme attack. More recently enzyme inhibitors have been discovered that inactivate beta-lactamase. The combination of an enzyme inhibitor with a beta-lactam antibiotic, such as ampicillin, restores the antimicrobial activity of the beta-lactam against formerly resistant strains of staphylococci, Haemophilus influenzae, Enterobacteriaceae, and Bacteroides fragilis.

Ampicillin/sulbactam versus metronidazole-gentamicin in the treatment of soft tissue pelvic infections

The clinical efficacy and safety of ampicillin/sulbactam versus metronidazole-gentamicin were evaluated in a comparative, randomized, prospective study. Forty-four patients were enrolled: 22 received the ampicillin/sulbactam regimen, and 22 received the metronidazole-gentamicin combination. There were 33 cases of severe acute pelvic inflammatory disease, two tuboovarian abscesses, five cases of endomyometritis, and two cases of posthysterectomy pelvic cellulitis. Aerobic and anaerobic cultures from the infection sites yielded 447 microorganisms from 44 patients (an average of 10 bacteria per infection; 6.4 anaerobes and 3.7 aerobes). The most frequent isolates were Bacteroides sp., 54; Bacteroides bivius, 17; black-pigmented Bacteroides, 12; Bacteroides disiens, 11; Fusobacterium, 13; Peptostreptococcus anaerobius, 24; Peptostreptococcus asaccharolyticus, 21; anaerobic gram-positive cocci, 34; Gardnerella vaginalis, 29; Neisseria gonorrhoeae, 17; alpha-hemolytic streptococci, 15; and Escherichia coli, five. Clinical cure was noted in 19 of 20 patients treated with ampicillin/sulbactam and 18 of 21 patients treated with metronidazole-gentamicin. One treatment failure occurred in the ampicillin/sulbactam group in a patient who required antichlamydial therapy and had a complex left adnexal mass consistent with an abscess. The cases of metronidazole-gentamicin failure included two patients initially diagnosed as having tuboovarian abscesses who required a change in antibiotic therapy to control the infections. The third patient had postabortion endomyometritis that did not respond to metronidazole-gentamicin therapy within 48 hours, and required a change of medication. No adverse hematologic, renal, or hepatic effects were noted in either group of patients.

Microbiology of the female genital tract

Patients who contract genital tract infections are predominantly young, are otherwise healthy, and generally respond well to treatment for bacterial infections. These infections are most commonly polymicrobial in etiology, with several noteworthy exceptions. Often there is an inciting event such as childbirth, surgical intervention, pregnancy termination or intrauterine contraceptive device insertion. With treatment, prognosis for cure is excellent; however, sequelae such as recurrent infections, infertility, or ectopic pregnancy can be serious. Bacteria encountered in the female genital tract can be divided into aerobic and anaerobic organisms. Among the aerobic gram-positive organisms, several varieties of streptococci such as Group B streptococci and enterococci occur frequently. Staphylococcus aureus is an infrequent but important pathogen. Among the aerobic gram-negative organisms, the most common is Escherichia coli. Klebsiella sp. and Proteus sp. occur in about 5% of genital tract infections. Species that are more resistant to antibiotics, such as Pseudomonas aeruginosa and Enterobacter sp., occur in approximately 1% or 2% of these cases and are more likely to appear in patients who have previously received antibiotic therapy or who have been hospitalized for some time. Among the anaerobic organisms, the most common gram-positive isolates are Peptostreptococci and Peptococci. Clostridia sp. occurs less frequently. Among the anaerobic gram-negative organisms, the Bacteroides sp. most frequently encountered are Bacteroides bivius and Bacteroides disiens. Bacteroides fragilis is still a common problem but appears to be less predominant. Other organisms encountered are Chlamydia trachomatis, the genital mycoplasmas, yeasts, protozoa, and viruses.

Cefoperazone versus clindamycin plus gentamicin for obstetric and gynecologic infections

Cefoperazone was compared with clindamycin plus gentamicin for the treatment of pelvic infections. Of 102 women, 95 (93%) demonstrated a good clinical response (47 with cefoperazone and 48 with clindamycin plus gentamicin). Of the seven failures, four were secondary to side effects and three were clinical failures.

Comparative clinical evaluation of ticarcillin plus clavulanic acid versus clindamycin plus gentamicin in treatment of post-cesarean endomyometritis

A new single-antibiotic combination of ticarcillin and clavulanic acid was compared with the standard two-drug regimen of clindamycin and gentamicin in the treatment of post-cesarean endomyometritis. The regimens were as follows: 3 g of ticarcillin plus 100 mg of clavulanic acid intravenously every four hours; or 600 mg of clindamycin intravenously every six hours plus 3 to 5 mg/kg per day of gentamicin intramuscularly. The prospective randomized schedule was calculated such that half the patients were assigned to each treatment group. The diagnosis of endomyometritis was based upon an elevated oral temperature of 100.4 degrees F or higher on any two occasions, excluding the first 24 hours after delivery, uterine tenderness, and the absence of other foci of infection. Lochial discharge was foul in most cases. Forty-seven patients were treated. Treatment was successful in all patients who received clindamycin and gentamicin; ticarcillin plus clavulanic acid failed in two of 23 (9 percent) patients. Patients in whom treatment failed did not appear to be different from those in whom treatment was successful on demographic variables or in terms of risk factors for endomyometritis. The difference between the treatment failure rates was not statistically significant. This study suggests that the single-drug combination of ticarcillin plus clavulanic acid is effective in the treatment of post-cesarean endomyometritis when compared with the standard regimen of clindamycin and gentamicin.

Moxalactam versus clindamycin plus tobramycin in the treatment of obstetric and gynecologic infections

The clinical efficacy of moxalactam versus clindamycin/tobramycin was evaluated in a comparative, randomized, prospective study. Sixty patients were treated: 30 with moxalactam and 30 with clindamycin/tobramycin. There were 15 cases of tuboovarian abscess, 36 cases of severe pelvic inflammatory disease with peritonitis, eight cases of endomyometritis, and one wound abscess. Aerobic and anaerobic cultures from the sites of infection yielded 441 microorganisms from 53 patients; an average of 8.3 bacteria per infection (4.5 anaerobes and 3.8 aerobes). The infections tended to be mixed aerobic-anaerobic with anaerobes isolated in 90% of cases. The most frequently isolated possible pathogens were Bacteroides sp. (37), Bacteroides bivius (23), Bacteroides asaccharolyticus (12), Peptococcus asaccharolyticus (29), Peptostreptococcus anaerobius (19), unidentified anaerobic gram-positive cocci (18), Escherichia coli (17), nonhemolytic streptococci (16), Neisseria gonorrhoeae (13), and Gardnerella vaginalis (38). Clinical cure was noted in 29 of 30 moxalactam-treated and 29 of 30 clindamycin/tobramycin-treated patients. Moxalactam was effective in five of six cases of tuboovarian abscess, all 22 cases of pelvic inflammatory disease with peritonitis, the one case of endomyometritis and the one wound abscess. Clindamycin/tobramycin was effective in eight of nine cases of tuboovarian abscess, all 14 cases of pelvic inflammatory disease with peritonitis, and all seven cases of endomyometritis. No adverse hematologic, renal, or hepatic effects were noted with either regimen.

Imipenem/cilastatin in the treatment of obstetric and gynecologic infections

Fifty-five patients with soft tissue pelvic infections were treated with imipenem/cilastatin 500 mg intravenously every six hours for a minimum of four days. Six patients were unevaluable, one because of protocol non-compliance and five because no pathogen was isolated. At enrollment, mean temperature was 39.5 degrees C and the mean white blood cell count was 14,700. Of 49 evaluable patients, 43 (87.8 percent) had complete clinical cures. In three of the six patients with clinical failures, subsequent alternative antibiotic treatment also failed and they required operative intervention for pelvic abscess. In two of the patients with failures, antibiotic-associated pseudomembranous colitis developed after three days of imipenem/cilastatin therapy, requiring discontinuation of the medication. At the time of discontinuation, both patients had clinical failures. All microbiologic isolates were susceptible to imipenem/cilastatin, although at least one pathogenic organism persisted in two patients with clinical failures despite apparent in vitro susceptibility of the organism to imipenem/cilastatin. Imipenem/cilastatin is a promising agent for the empiric treatment of serious obstetric and gynecologic infections although surgery often remains a necessary treatment for pelvic abscess regardless of initial antibiotic choice.

In vitro activity of cefbuperazone and other antimicrobial agents against isolates from the female genital tract

Cefbuperazone (BMY 25182), a new cephamycin, showed activity similar to those of moxalactam and other cephalosporin-cephamycins against aerobic and anaerobic bacteria from female genital tract infections. MICs of the antimicrobial agents were less than or equal to 16 micrograms/ml for greater than 97% of organisms tested. All of the anaerobic bacteria tested were susceptible to clindamycin, metronidazole, and chloramphenicol.

Clindamycin levels in reproductive tissues

Clindamycin is widely used in a variety of obstetric and gynecologic infections. Despite in vitro and clinical evidence of activity against anaerobes, genital organ tissue levels resulting from intravenous administration of the drug have not previously been reported. Following a single intravenous infusion of 600 mg of clindamycin phosphate, tissue levels were determined in operative specimens obtained from ten women. Specimens of cervix, uterus, fallopian tube, and ovary were obtained, and mean Clindamycin levels for each site were: cervix, 2.63 micrograms/ml; endometrium, 5.58 micrograms/ml; myometrium, 2.39 micrograms/ml; fallopian tube, 2.96 micrograms/ml; and ovary, 3.74 micrograms/ml. The mean serum level was 6.26 micrograms/ml at the time of uterine artery interruption. The clindamycin concentrations at all sites exceeded the usual therapeutic minimal inhibitory concentration, substantiating the usefulness of clindamycin in obstetric and gynecologic anaerobic infections.

Susceptibility profiles of potential aerobic and anaerobic pathogens isolated from hysterectomy patients

A total of 1140 aerobic and anaerobic isolates were recovered from cultures of specimens from the reproductive tracts of 435 uninfected patients who underwent elective hysterectomy. Standard minimum inhibitory concentration susceptibility studies were performed on these isolates to 13 newer penicillins, cephalosporins, and some traditional antimicrobial agents. These data were generated to evaluate the in vitro efficacy of these antibiotics for potential use in prophylaxis or as a single agent for treatment of polymicrobial infections of the female pelvis. The minimum inhibitory concentration data for each antibiotic against 16 genera of aerobic and nine genera of anaerobic bacteria were determined and were used to compare the in vitro antimicrobial activity of newer antibiotics to that of the more traditional antibiotics. Of the antimicrobial agents tested, piperacillin had the highest in vitro activity against these isolates of any antibiotic tested.