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

Use of third-generation cephalosporins. Anaerobes

The third-generation cephalosporins have an increased spectrum of activity against gram-negative bacteria, moderate activity against anaerobic bacteria, and reduced anti-gram-positive activity as compared with earlier cephalosporins. This spectrum allows the drugs to be considered as monotherapy for the treatment of mixed aerobic-anaerobic infections and as prophylaxis in patients in whom such mixed flora are expected. In vitro testing of anaerobes with the third-generation cephalosporins shows susceptibility to be method dependent, with regional differences also observed. The microtube broth dilution method shows the best relationship to in vivo results. Moreover, the apparent in vitro susceptibility or resistance does not always correlate with clinical efficacy. Clinical studies indicate that the expanded-spectrum third-generation cephalosporins may be used in place of combination therapy in patients with polymicrobial infection or as prophylaxis when mixed microflora are expected.

Placental transfer of cefazolin and piperacillin in pregnancies remote from term complicated by Rh isoimmunization

Although the administration of prophylactic antibodies for intrauterine transfusion is controversial, little information is available regarding placental transfer of antibiotics administered to the mother, or whether the presence of hydrops affects this placental transfer. Sixteen intravascular intrauterine transfusions were performed in 10 patients. Seven (10 procedures) patients were given 2 gm of cefazolin before the procedure and samples were obtained by fetal vascular access. Three patients (six procedures) were given 4 gm of piperacillin and samples were similarly obtained. Specimens were obtained for fetal serum, maternal serum, and amniotic fluid antibiotic concentration. The mean serum cefazolin concentration in hydropic fetuses was 18.04 +/- 3.37 micrograms/ml, and in nonhydropic fetuses the concentration was 21.02 +/- 17.8 micrograms/ml (p = 0.72). The mean fetal serum concentration of piperacillin was 22 +/- 12 micrograms/ml. The placental transfer of both drugs was similar. We conclude that the transplacental passage of these antibiotics is prompt and that the presence of hydrops does not significantly impair the passage of cefazolin.

Infection on a gynecologic oncology service

Little information is available pertaining to infectious morbidity in women with genital malignancy. To define the magnitude of this problem, all patients admitted to the gynecologic oncology services at the University of Michigan Medical Center between January 1, 1986, and December 31, 1986, were followed prospectively for the development of infectious morbidity. One hundred nine bacteriologically confirmed infections occurred in 297 patients during 510 admissions. An additional 31 postoperative patients received empiric therapy for presumed infection. Urinary tract (54) and wound (22) infections were the most commonly confirmed infections. The pathogens isolated from oncology patients were significantly different in frequency of isolation and antibiotic sensitivity when compared with pathogens isolated from women developing infections on the benign gynecology service. Women with genital malignancies are at high risk for the development of a variety of infections by resistant pathogens, emphasizing the importance of obtaining cultures prior to initiation of therapy and carefully selecting the antibiotics to be prescribed.

Single-dose prophylaxis for vaginal and abdominal hysterectomy

The practice of administering perioperative antimicrobials to uninfected patients undergoing elective surgical procedures has been subjected to careful prospective investigative scrutiny during the past two decades. A wound classification system was developed, helping to identify procedures for which prophylaxis did not provide benefit to the patient. Guidelines for prophylaxis in hysterectomy were proposed and risk factors were sought. Pharmacokinetics and spectrum of antibacterial activity, although variables of paramount importance in predicting success in the treatment of established infections, were discovered to have questionable impact on prophylactic efficacy. Duration of antimicrobial administration has gradually diminished from the total length of hospital stay to a single preoperative dose without increased risk of infection; efficacy may be related to route of administration. The wisdom of using newer agents for prophylaxis is addressed and questioned.

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.

Aminoglycosides in gynecologic infections

Aminoglycosides have always had a major role in the treatment of gynecologic infections. This therapeutic emphasis has been based upon the bactericidal activity of the aminoglycosides against gram-negative aerobes. This group of organisms is important to the gynecologist because of their frequent isolation from soft tissue, urinary sites, and the bloodstream in women with nosocomial or community-acquired pelvic infections. In the past decade, there has been increasing clinical awareness of the multi-bacterial nature of these soft tissue pelvic infections. A major therapeutic change directed against gram-negative anaerobes has been the substitution of more effective agents like clindamycin or metronidazole for the penicillin arm of the older penicillin-aminoglycoside combination. The majority of intra-abdominal and pelvic infections treated by gynecologists occur in patients who are younger and usually healthier than those with similar infections who are treated by general surgeons. Consequently, in many instances, single drug therapy with a cephalosporin (usually cefoxitin) is adequate, if combined with surgical drainage when indicated. However, there is an increasingly larger group of patients who are significantly older and who may also have pelvic malignancies. In addition, they may be immunocompromised. Infections in this group mandate the use of the most effective antimicrobial agents that will cover the broadest spectrum. When anaerobic bacteria are involved, either clindamycin or metronidazole are acceptable choices; for aerobic gram-negative organisms, an aminoglycoside should be used. Recent studies suggest that amikacin may be the best choice, since it is associated with a low level of bacterial resistance and has been shown to reduce levels of resistance to other aminoglycosides. Amikacin has become the "gold standard" for comparisons with any new cephalosporins or penicillins. New developments will modify the use of aminoglycosides in the future. The expansion of oncology care with immune-system-modifying chemotherapy and radiation will expose patients to the dangers of gram-negative sepsis. Aminoglycosides are a logical part of the initial therapeutic regimen for these septic patients. On the other hand, the majority of gynecologic patients with pelvic infections are young and healthy. Recent studies have demonstrated that as many as 40 percent of these women will be underdosed by standard treatment regimens based upon ideal body weight. This means that patients receiving aminoglycosides will require monitoring of peak and trough levels to insure therapeutic drug levels.(ABSTRACT TRUNCATED AT 400 WORDS)

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.