A multicenter clinical trial of oral ribavirin in HIV-infected people with lymphadenopathy: virologic observations. Ribavirin-LAS Collaborative Group.

A double-blind, randomized, placebo-controlled trial comparing two daily doses of oral ribavirin (600 and 800 mg) and a placebo was performed at four medical centers geographically distributed throughout the USA. One hundred and sixty-four HIV-infected adult men with lymphadenopathy were enrolled over a 2-month period and received active treatment for 24 weeks followed by a 4-week interval during which they did not receive the study drug. A marked interlaboratory variation in HIV isolation from peripheral blood mononuclear cells was observed, underscoring the critical role of quality assurance in similar multicenter trials. Nevertheless, the combined data indicate that ribavirin did not significantly suppress HIV activity (on measurement of reverse transcriptase activity) after week 6 or reduce serum p24 antigenemia.

Infection and risk of ischemic stroke: differences among stroke subtypes.

BACKGROUND AND PURPOSE: Although prior studies have demonstrated that 25% to 35% of stroke patients have had a recent infection, the role of infection as a risk factor remains unclear. Our aim was to characterize the effect of infectious/inflammatory syndromes on stroke risk. METHODS: Case-control and crossover analyses of 233 cases and 363 controls aged 21 to 89 years were performed. Cases were patients hospitalized with a first ischemic stroke at a Los Angeles, California, medical center. Controls were outpatients in the hypertension, diabetes, and general medical clinics. All subjects were administered a neurological examination, an infection/inflammation (I/I) examination, and an interview to elicit recent I/I history at baseline (within several days of stroke onset) and again approximately 2 months later. Three physicians classified subjects by the presence or absence of I/I within 1 month of the index dates, based on findings of the I/I examination, the interview report, and laboratory results. RESULTS: Infections, either total or specific, were not found more frequently in cases than controls. However, patients with a recent respiratory tract infection suffered more often from large-vessel atherothromboembolic or cardioembolic stroke than did patients without infection (48% vs 24%, P=0.07). The age- and sex-adjusted relative risk estimate for these subtypes was 1.75 (95% CI, 0.86 to 3.55). The risk was notably high for those without stroke risk factors: 4.15 (95% CI, 1.22 to 14.1) for normotensives, 2.71 (95% CI, 1.04 to 7.06) for nondiabetics, and 1.74 (95% CI, 0.74 to 4.07) for nonsmokers. Patients with a recent respiratory infection also had a more severe neurological deficit on admission than those without infection (P=0.05). CONCLUSIONS: Our results suggest that respiratory tract infection may act as a trigger and increase the risk of large-vessel and/or cardioembolic ischemic stroke, especially in those without vascular risk factors.

Randomized double-blind placebo-controlled trial of peptide T for HIV-associated cognitive impairment.

BACKGROUND: Cognitive impairment is a common consequence of human immunodeficiency virus (HIV) infection, and dementia is one of the diseases that defines the acquired immunodeficiency syndrome. Peptide T (d-ala-peptide-T-amide) has been reported to block the binding of gp120 to brain tissue and to protect neurons from the toxic effects of gp120 in vitro. In pilot studies, administration of peptide T to HIV-positive patients with cognitive impairment was associated with improvement in cognition and constitutional symptoms. OBJECTIVE: To determine whether the intranasal administration of peptide T would improve cognitive function of HIV-positive patients with cognitive impairment. PATIENTS AND METHODS: This was a 3-site, double-blind, placebo-controlled trial of peptide T given intranasally at a dosage of 2 mg 3 times a day for 6 months. Participants were HIV-seropositive persons with evidence of cognitive deficits on a screening test battery. Concomitant antiretroviral therapy was allowed. Randomization to the 2 study arms was balanced according to several stratification variables, such as CD4+ cell count, severity of cognitive impairment, and antiretroviral therapy at study entry. A comprehensive neuropsychological (NP) battery, which yielded 23 scores, was administered at baseline and the study end point. The primary outcome measure was a global NP score derived from the 23 standardized scores. The efficacy end point was the change in NP score at 6 months compared with baseline. Secondary efficacy measures were 7 cognitive domain scores and deficit scores of global and domain performance. The patients who completed the baseline and final NP evaluations (after at least 4 months in the randomized treatment arm) were included in the efficacy analyses. Additional analyses were conducted on subgroups of patients according to the CD4+ count and baseline NP deficit. The incidence of NP improvement in the 2 treatment arms was also compared. RESULTS: There was no statistically significant difference between the peptide T and placebo groups on the global NP change score, the individual domains, or the deficit scores. Because of an imbalance in the baseline CD4+ cell count between treatment arms, analyses were also adjusted for this variable. These CD4+-adjusted analyses suggested (P = .07; analysis of covariance [ANCOVA]) a greater improvement in the peptide T group. Subgroup analyses indicated a treatment effect for patients whose CD4 cell count was above 0.200 x 10(9)/L (200 cells/microL) at baseline. Moreover, peptide T treatment was associated with overall cognitive improvement in patients with baseline global deficit scores of at least 0.5, while overall deterioration was more common among the placebo group (P = .02; Mantel-Haenszel chi(2) test). CONCLUSIONS: Peptide T was not significantly different from placebo on the study primary end points. However, additional analyses indicated that peptide T may be associated with improved performance in the subgroup of patients with more evident cognitive impairment (ie, NP global deficit score > or = 0.5) or with relatively preserved immunological status (ie, CD4+ cell count > 0.200 x 10(9)/L).

A multicenter clinical trial of oral ribavirin in HIV-infected patients with lymphadenopathy. The Ribavirin-LAS Collaborative Group.

A double-blind, randomized, placebo-controlled trial comparing two daily doses of oral ribavirin and placebo was conducted at four medical centers. One hundred sixty-four adult men with lymphadenopathy were enrolled over a 2-month period and randomized to receive ribavirin 800 mg (53 subjects), ribavirin 600 mg (55 subjects), or placebo (56 subjects). Active treatment was administered for 24 weeks followed by a 4-week washout period. Nine subjects receiving placebo, four receiving ribavirin 600 mg, and none in the 800 mg group developed AIDS during the 24 weeks of active treatment. One patient randomized to the 800 mg group had Kaposi's sarcoma at study entry and was included in the intent-to-treat analysis. An overall significant difference in progression to AIDS was observed among the three treatment groups (p = 0.028) with patients randomized to receive 800 mg having a significantly longer time to AIDS than placebo patients (p = 0.012; relative risk, 9.0; 95% confidence interval, 1.1 to 70.8). There was no significant difference between the 600 mg and placebo groups (p = 0.15; relative risk, 2.3; 95% confidence interval, 0.7 to 7.6). Baseline CD4 cell count and hematocrit made independent contributions and formed a multivariate prognostic set for these progression data. The significant treatment superiority of 800 mg compared to placebo remained after adjustment for these factors (p = 0.019). After deletion of patients with major protocol violations at entry, the difference between the 800 mg and placebo treatment remained significant (p = 0.021).(ABSTRACT TRUNCATED AT 250 WORDS)

Compassionate use of norfloxacin.

Norfloxacin, a new oral fluoroquinolone, has a spectrum of activity and pharmacology that suggest it may be useful in certain infections in which other agents are inactive or have anticipated toxicity. This report is an analysis of 61 "compassionate" requests for norfloxacin that resulted in 42 treatment courses. The reasons for use included multiresistant pathogens susceptible only to norfloxacin in 42 percent, failure of prior use of a marketed antibiotic in 34 percent, and preferred use of norfloxacin due to anticipated toxicity from an aminoglycoside in 32 percent or from other agents in 9 percent. Infections treated included 29 complicated urinary tract infections, 23 involving multiresistant Pseudomonas species, and 10 gastrointestinal infections, seven involving Salmonella species. Prophylaxis of infection was initiated in three neutropenic patients with leukemia. The duration of norfloxacin therapy ranged from eight to 28 days at a daily dose of 800 mg (400 mg twice daily). Norfloxacin treatment resulted in clinical cure or improvement in 84 percent of patients and eradicated the etiologic pathogen(s) 52 percent of the time. In Pseudomonas species infections, cure was achieved in 29 percent of patients and 57 percent showed improvement; the pathogen was eradicated in 43 percent of these infections. Resistance developed in four of the eight Pseudomonas species infections that persisted. Based on a review of compassionate therapy cases, it appears that norfloxacin is effective oral therapy for many complicated urinary and gastrointestinal infections for which other agents cannot be used because of bacterial resistance or anticipated toxicity.

Eflornithine treatment of refractory Pneumocystis carinii pneumonia in patients with acquired immunodeficiency syndrome.

Eflornithine was offered as compassionate treatment of 33 episodes of Pneumocystis carinii pneumonia in 31 patients with acquired immunodeficiency syndrome who were intolerant of and/or unresponsive to conventional trimethoprim-sulfamethoxazole or pentamidine therapy. A full course of eflornithine consisted of ten days at 400 mg/kg/d but no more than 30 g/d in four divided intravenous doses, four days at 300 mg/kg/d in four divided intravenous doses, and then up to six weeks at 300 mg/kg/d in four divided oral doses where tolerated. Of 33 patient-episodes, 15 patients were discharged from the hospital without need for supplemental oxygen after receiving ten or more days of parenteral therapy and were classified as responders. Of the 16 episodes classified as treatment failures, death occurred within the first 10 days of therapy in 12, and supplemental oxygen could not be withdrawn in 4. The other two patients left the hospital without need of oxygen after receiving one and six days of treatment with eflornithine and were not considered evaluable for efficacy. The most serious adverse effect was thrombocytopenia, which occurred in 12 of 19 patients treated for ten days or more. Serious bleeding associated with thrombocytopenia was observed in two patients. Other common adverse effects were anorexia, nausea, and diarrhea. Prior to receiving eflornithine, 13 of 15 responders had received ten or more days of conventional therapy without demonstrating clinical improvement. Two had improved while receiving conventional therapy but were switched to eflornithine because of a treatment-limiting adverse effect of standard therapy. These results suggest that eflornithine may be useful as an alternative therapeutic agent for Pneumocystis carinii pneumonia. Studies designed to determine proper dosage, duration of therapy, and efficacy as primary therapy are warranted.

Unrecognized HIV-1 infection in inner-city hospital emergency department patients.

To determine the prevalence of unrecognized human immunodeficiency virus (HIV)-1 infections in patients presenting to an inner-city hospital emergency department, medical records were reviewed from 1,945 patients diagnosed with diseases not related to HIV or acquired immunodeficiency syndrome. The overall seroprevalence was 2.1% (40): 1.8% (11) in nontrauma versus 3.0% (29) in trauma patients. The highest prevalence was found in black, male, uninsured patients.

Susceptibility testing of Listeria monocytogenes. A reassessment of bactericidal activity as a predictor for clinical outcome.

In vitro susceptibility testing of Listeria monocytogenes most often reveals both ampicillin and penicillin as inhibitory as opposed to bactericidal with activity comparable to chloramphenicol and tetracycline. Yet, the former two penicillins are more effective for Listeria meningitis than are the latter agents. Accordingly, we reassessed the bactericidal activity of agents used in listeriosis in order to determine in vitro methodology that would be more predictive of clinical outcome. We found that bactericidal activity for greater than 48 hr by either minimum inhibitory-minimum bactericidal concentration (MIC-MBC) testing or time-kill kinetic studies was the best predictor of clinical efficacy. This correlation may be due to Listeria being a slow-growing microorganism. In addition to ampicillin and penicillin, we found trimethoprim-sulfamethoxazole, vancomycin, and imipenem to exhibit bactericidal activity for 48 hr. For the first two agents, this is in agreement with the results of clinical experience.

Comparative in vitro activities of norfloxacin (MK-0366) and six commonly used antimicrobial agents against 199 urinary isolates showing various degrees of antibiotic resistance.

The in vitro activity of norfloxacin (MK-0366), a new oral antimicrobial agent, was compared to that of ampicillin, tetracycline, cefazolin, nitrofurantoin, nalidixic acid, and trimethoprim against 199 gram-negative urinary isolates. Among these isolates were ampicillin-resistant Escherichia coli and gentamicin-resistant Pseudomonas aeruginosa and Serratia marcescens. Norfloxacin was the most active antimicrobial agent tested against all isolates studied; it was the only agent active against P. aeruginosa and S. marcescens.

Pharmacoeconomics of piperacillin/tazobactam and imipenem/cilastatin in the treatment of patients with intra-abdominal infections.

Costs involved in using piperacillin 4 g/tazobactam 500 mg, given as intermittent intravenous infusions every 8 hours, were compared with those for imipenem/cilastatin 500 mg, given as intermittent intravenous infusions every 6 hours, for the treatment of patients with gangrenous or perforated appendicitis. A total of 88 patients were included in our cost analyses: 42 patients in the piperacillin/tazobactam group and 46 patients in the imipenem/cilastatin group. Durations (mean +/- SD) of antibiotic therapies were 7.8 +/- 3.3 days and 7.1 +/- 2.6 days for the piperacillin/tazobactam and imipenem/cilastatin groups, respectively. No statistical significance was found for the difference in duration of therapy (P = 0.376). Total drug treatment costs were $538.83 +/- $385.33 for the piperacillin/tazobactam group and $687.66 +/- $345.37 for the imipenem/cilastatin group. This difference in treatment cost was statistically significant (P = 0.0001). The need for laboratory tests and the use of other medications were not different between the two groups. Total hospital-days charges were higher for the piperacillin/tazobactam group ($18,339.76 +/- $6090.38) compared with the imipenem/cilastatin group ($16,150.00 +/- $5088.60) (P = 0.052). These findings suggest that length of hospital stay should be the economic focus of antibiotic therapy.

Meropenem versus tobramycin with clindamycin in the antibiotic management of patients with advanced appendicitis.

BACKGROUND: Meropenem (MP), a new carbapenem antibiotic, has excellent antimicrobial activity against the enteric flora commonly encountered in acute appendicitis. Although similar to imipenem, it may have clinical advantages. STUDY DESIGN: We compared patients with advanced appendicitis (gangrenous or perforated) treated with 1,000 mg MP every eight hours with those given the combination of tobramycin 5 mg/kg/day at eight hour intervals and clindamycin 900 mg every eight hours. Both treatments were given intravenously. Patients were randomized to either group of the double-blind study. RESULTS: Of 129 evaluable cases, 63 received MP and 66 received both tobramycin and clindamycin (T/C). The two groups were similar in age, sex, and severity of disease. The mean number of days of postoperative fever (MP = 3.1 +/- 1.7 SD compared to T/C = 4.4 +/- 2.2 SD, p < or = 0.01), days of antibiotic therapy (MP = 6.1 +/- 1.6 SD compared to T/C = 7.3 +/- 2.2 SD, p = 0.01), and therefore hospital stay (MP = 8.0 +/- 3.5 SD compared to T/C = 9.4 +/- 2.6 SD, p < 0.01) were significantly better for patients treated with MP. No difference was found between the numbers of failures in each group (MP = 5 compared to T/C = 6). CONCLUSIONS: This study demonstrates a small but significant reduction (approximately one day) in post-operative fever, duration of antibiotic treatment, and hospital stay for patients treated with MP compared to those treated with T/C.

Analysis of cefepime tissue penetration into human appendix.

Cefepime is a new extended-spectrum cephalosporin with gram-positive and gram-negative coverage including Staphylococcus aureus and Pseudomonas aeruginosa. We evaluated the drug's plasma, peritoneal fluid, and appendix tissue concentrations in patients with a postoperative diagnosis of perforated or gangrenous appendicitis. Patients 18 years of age or older were randomly assigned to receive either cefepime 2 g every 12 hours plus metronidazole 500 mg every 6 hours intravenously, or gentamicin 1.5 mg/kg plus clindamycin 900 mg every 8 hours intravenously. During surgery, appendix tissue, plasma, and peritoneal fluid samples were obtained, and frozen at -70 degrees C for high-pressure liquid chromatographic analysis. Thirty-five patients with perforated (26) or gangrenous (9) appendicitis had concentrations acceptable for analysis. The mean time between the administration of cefepime and the time of sampling (referred to as delta time) was 5.99 +/- 3.75 hours (mean +/- SD). The values for plasma (n = 34), tissue (n = 33), and peritoneal fluid (n = 25) concentrations were 16.27 +/- 21.87 micrograms/ml, 4.84 +/- 6.15 micrograms/g, and 14.4 +/- 22.84 micrograms/ml, respectively. The appendix tissue:plasma ratio was 0.66 +/- 0.52 and the peritoneal fluid:plasma ratio was 0.66 +/- 0.51. Spearman rank correlations indicated statistically significant correlations between plasma concentration (r = -0.889; p less than 0.0001), peritoneal fluid concentration (r = -0.783; p = 0.0002), and appendix tissue concentration (r = -0.704; p = 0.0016) versus delta time.(ABSTRACT TRUNCATED AT 250 WORDS)

Antibiotic management of surgically treated gangrenous or perforated appendicitis. Comparison of gentamicin and clindamycin versus cefamandole versus cefoperazone.

A study of 130 adult patients with surgically treated gangrenous or perforated appendicitis was undertaken to evaluate the efficacy of three antibiotic regimens. Forty-eight patients received cefamandole, 40 were given the combination of clindamycin and gentamicin, and 42 were treated with cefoperazone. Side effects from these antibiotics were infrequent and mild. When all cases were compared for infectious failure, clindamycin-gentamicin showed a clear advantage over cefamandole. Because of the heterogeneity of the total study population, patients with perforation and peritonitis were compared separately. This analysis confirmed the advantage of clindamycin-gentamicin over cefamandole. In addition, it appears that clindamycin-gentamicin is more efficacious than cefoperazone.

Cost analysis of antibiotics in the management of perforated or gangrenous appendicitis.

Costs associated with treating patients for gangrenous or perforated appendicitis were compared. Patients received single agent therapy with cefoperazone or cefamandole or combination antibiotics consisting of clindamycin and serum level-adjusted gentamicin. Forty-eight patients received cefamandole, 47 received cefoperazone, and 52 received combination clindamycin and gentamicin. Costs to the pharmacy for drugs were greater for the combination therapy; however, the higher failure rate associated with the cephalosporins created greater expenses for the single agent therapy than for combination therapy.

Gentamicin-resistant pseudomonal infection. Rationale for a redefinition of ophthalmic antimicrobial sensitivities.

Eight pseudomonal species were involved in 106 invasive infections of the eye; all were community acquired. Eighteen percent of the total and 9% of the Pseudomonas aeruginosa strains were gentamicin resistant, as defined using conventional criteria. All 10 cases of "resistant" pseudomonal (nine P. aeruginosa) keratitis responded satisfactorily to treatment with gentamicin. The resistance breakpoint (defined by safe serum levels in parenteral therapy) for most P. aeruginosa is much lower than ocular gentamicin levels achievable by optimal local application. We argue for a specific ophthalmologic definition of antibiotic resistance in infections of the cornea and external eye. MIC quantitative determinations of ocular isolates would provide more useful information to ophthalmologists than conventional qualitative disc sensitivity testing.

Prospective randomized study of two different doses of clindamycin admixed with gentamicin in the management of perforated appendicitis.

Septic complications after surgery for enterogenous peritonitis are minimized by adjuvant antibiotics effective against aerobes and anaerobes. Historically, "gold standard" therapy included an aminoglycoside plus clindamycin, the latter given at 600 mg intravenous piggyback (IVPB), every 6 hours. Clindamycin pharmacokinetics suggests that it can be given q8h and admixed with gentamicin, thereby markedly reducing the cost of administration. Although this is now common practice, there is no prospective study comparing the efficacy of the two dose schedules in peritonitis. This study was designed to test the hypothesis regarding the clinical efficacy of the two regimens. One hundred twenty-six patients with gangrenous (n = 34) or perforated appendicitis (n = 91) were randomized (2:1) to receive gentamicin admixed with clindamycin 900 mg IVPB every 8 hours (Group I n = 80) or gentamicin IVPB q8h plus clindamycin 600 mg IVPB every 6 hours (Group II n = 46). Appendectomy was performed, and aerobic and anaerobic cultures were obtained. Twenty-one patients had simultaneous determinations of clindamycin levels in plasma, peritoneal fluid, and appendix. Outcome analysis revealed no significant differences in postoperative days of fever, days non per os, antibiotic therapy, or hospitalization. There were 6 failures (4 abscesses and 2 wound infections) in Group I and 4 failures (1 abscess and 3 wound infections) in Group II. Both antibiotic regimens provided clinically equivalent results in mixed infections due to aerobic and anaerobic bacteria. The admixed clindamycin, administered every 8 hours, results in at least 20% reduction in costs. This is an important consideration.

Ceftazidime/clindamycin versus tobramycin/clindamycin in the treatment of intra-abdominal infections.

In order to assess the efficacy and toxicity of ceftazidime as a substitute for aminoglycosides in the treatment of intra-abdominal sepsis, a prospective randomized trial was conducted. Ninety-four patients (49% trauma) were randomized to receive ceftazidime/clindamycin (CAZ/C) (n = 47) or tobramycin/clindamycin (T/C) (n = 47). CAZ (2.0 gm) and C (0.9 gm) were administered intravenously every 8 hours while T dosage was adjusted to maintain peak (5-8 mg/L) and trough (less than 2 mg/L) concentrations. Age, sex, baseline serum creatinine, and etiology of infection were comparable in the two groups. Clinical cure was similar in culture-positive and culture-negative patients who received CAZ/C (94% vs 88%). The clinical cure rate however was significantly lower in the T/C culture positive (73%) than in the culture negative patients (100%) (P = 0.016). Pathogenic organisms were eradicated in 100% (30/30) and 76% (13/17) of CAZ/C and T/C patients, respectively (P = 0.0006). Nephrotoxicity Nephrotoxicity or ototoxicity was observed in none of the CAZ/C patients and in one and two T/C patients, respectively. CAZ/C more effectively eradicated the bacteria isolated from these patients and no significant difference in clinical response was observed in culture-positive patients. These findings plus the lack of toxicity suggest that CAZ/C is an effective alternative for treatment of IAI.

A cost comparison of intramuscular versus intravenous imipenem.

Previously reported clinical trials of imipenem-cilastatin 500 mg given intravenously every 6 hours (intravenous group) and imipenem-cilastatin 750 mg given intramuscularly every 12 hours (intramuscular group) were analyzed for relative cost savings. Acquisition costs were significantly higher for the intravenous group for intravenous supplies (30.6 +/- 7.9 dollars) when compared to the intramuscular group (0.98 +/- 0.03 dollars) (p less than 0.05). Also, significantly higher cost (p less than 0.05) was noted for salaries of pharmacists and technicians for manufacturing in the intravenous group (5.8 +/- 1.5 dollars) as compared to the intramuscular group (2.4 +/- 0.7 dollars). Nursing administration costs were greater for the intramuscular group (15.6 +/- 4.8 dollars) when compared to the intravenous group (11.7 +/- 3.0 dollars). Incorporating all appropriate costs, the mean total drug therapy costs (TRX$) were significantly greater (p less than 0.01) for the intravenous group (458.17 +/- 175.17 dollars) as compared to the intramuscular group (298.0 +/- 114.76 dollars). Thus, the dosing of imipenem-cilastatin 750 mg intramuscularly every 12 hours is a more cost effective method of drug delivery with equal efficacy and safety when compared to imipenem-cilastatin 500 mg given intravenously every 6 hours.

Epidemiology, antimicrobial susceptibility, pathogenicity, and significance of Bacteroides fragilis group organisms isolated at Los Angeles County-University of Southern California Medical Center.

The epidemiology of species of the Bacteroides fragilis groups isolated at Los Angeles County-University of Southern California Medical Center was examined. In addition, frequency of resistance to six beta-lactam antibiotics (cefmetazole, cefotetan, ceftizoxime, imipenem, penicillin, and cefoxitin) and to clindamycin, chloramphenicol, and metronidazole was determined for each species. While B. fragilis was most commonly isolated, the other species of the B. fragilis group accounted for half of the isolates. Seven percent of 1,128 patients with infections due to species of the B. fragilis group were bacteremic. A review of bacteremic cases indicated that non-fragilis species were highly pathogenic. Resistance to clindamycin ranged from 8% to 22% among species and was most common among isolates of Bacteroides distasonis and Bacteroides thetaiotaomicron. Significant differences in antimicrobial activity were noted among the agents tested. Only imipenem, chloramphenicol, and metronidazole were predictably effective against non-fragilis species of the B. fragilis group. Prompt identification of species and susceptibility testing of clinical isolates of this group are needed if a newer beta-lactam agent or clindamycin is to be used for initial therapy.

Epidemiology and susceptibility of resistant Bacteroides fragilis group organisms to new beta-lactam antibiotics.

The epidemiology of the Bacteroides fragilis group and the interspecies frequencies of antibiotic resistance were examined. Susceptibilities were determined for 16 beta-lactam antibiotics, including seven new compounds. Fourteen percent of 287 patients with infection due to organisms of the B. fragilis group presented with bacteremia. Infections were as common among pediatric patients as among patients on the surgical services. Clindamycin resistance varied from 3% to 22% among the species. Resistance to clindamycin and cefoxitin was more likely to be encountered among Bacteroides species other than B. fragilis. These organisms were more commonly recovered from surgical wound specimens. Only N-formimidoylthienamycin showed predictably good activity against Bacteroides resistant to clindamycin or cefoxitin. The other new beta-lactam antibiotics had variable activities against these resistant strains, and significant differences were noted overall among the antimicrobial agents tested. Early speciation and susceptibility testing of clinical isolates of the B. fragilis group are needed, particularly if newer agents with unpredictable activities are used.