In vitro activity of cefotetan compared with that of other antimicrobial agents against anaerobic bacteria

The activity of cefotetan against 430 strains of anaerobic bacteria was compared with that of cefoxitin, ceftizoxime, clindamycin, metronidazole, and chloramphenicol. Percent susceptible values for the Bacteroides fragilis group were 60, 80, 29, 86, 100, and 100%, respectively. Percent susceptible values for the B. fragilis species were 91, 92, 46, 98, 100, and 100%, respectively. Non-B. fragilis-group Bacteroides species were inhibited very well (90 to 100%) by all drugs except ceftizoxime (80%). Cefotetan and metronidazole were the most active agents against Clostridium difficile. Percent susceptible values for all strains were 72, 79, 44, 82, 93, and 98%, respectively.

In vitro activity of cefoperazone plus sulbactam compared with that of other antimicrobial agents against anaerobic bacteria

The activity of two cefoperazone-sulbactam combinations against anaerobic bacteria was tested and compared both with that of cefoperazone alone and with that of other commonly used antimicrobial agents. Imipenem was the most active of the tested agents, followed by chloramphenicol, metronidazole, and cefoperazone-sulbactam (90 to 100% of bacterial growth inhibited). Clindamycin and cefoxitin inhibited approximately 80%, cefoperazone inhibited 63%, and penicillin G inhibited 47% of the strains tested. The agents were variable in activity against the Bacteroides fragilis group, with percents susceptible as follows: cefoperazone-sulbactam, imipenem, metronidazole, and chloramphenicol, 99 to 100%; cefoxitin and clindamycin, approximately 80%; cefoperazone, 49%; and penicillin G, 15.5%.

Uncommonly encountered, motile, anaerobic gram-negative bacilli associated with infection

Motile, anaerobic gram-negative bacilli belonging to the genera Butyrivibrio, Succinimonas, Succinivibrio, Anaerovibrio, Wolinella, Campylobacter, Desulfovibrio, Selenomonas, and Anaerobiospirillum are being recognized in clinical specimens with increasing frequency. Over a 12.5-year period at the VA Wadsworth Medical Center, 13 clinical specimens yielded one of these organisms. Six isolates were recovered from infected wounds, five from respiratory tract specimens obtained from patients with anaerobic pleuropulmonary infection, and two from peritoneal fluid of patients with intraabdominal infection. The distribution of isolates among the genera was as follows: Wolinella, five; Selenomonas, three; unidentifiable motile gram-negative bacilli, two; Desulfovibrio vulgaris, one; Campylobacter concisus, one; and Succinimonas, one. Our experience provides the first case reports of infection involving the last two organisms mentioned. Clinical features of the infections caused by these motile anaerobes were studied, and the current medical literature on such infections was reviewed.

The intraocular environment and experimental anaerobic bacterial endophthalmitis

Anaerobic bacteria are prevalent in conjunctival flora but have not been adequately investigated as possible causes of endophthalmitis. The mean oxidation-reduction potential (Eh) of the rabbit vitreous was found to be +25.1 mV, well within the limiting Eh value of many anaerobes. There was an oxygen pressure gradient in the vitreous ranging from 2.1 mm Hg immediately posterior to the lens to approximately 20 mm Hg adjacent to the medullary ray. Endophthalmitis was produced with pure cultures of Fusobacterium necrophorum, Propionibacterium acnes, and Peptostreptococcus magnus. Relatively small inoculates of F necrophorum caused severe, acute endophthalmitis with scleral perforation; P acnes and P magnus produced a self-limited endophthalmitis; and vitreoretinal fibrosis was a sequela of the Propionibacterium acnes infection.

Microbial flora in the bypassed jejunum of patients with biliopancreatic bypass for obesity

The microbial flora in the bypassed biliopancreatic intestinal segment was studied after obesity surgery. This procedure causes less diarrhea than jejunoileal bypass and appears to avoid extraintestinal complications. This report concerns type and quantity of bacteria colonizing the biliopancreatic segment and changes occurring after oral metronidazole treatment. Twelve specimens were aspirated in 10 patients via catheter inserted percutaneously during surgery. The specimens were plated immediately on selective and nonselective media under aerobic and anaerobic conditions. Essentially equal numbers of aerobes and anaerobes were recovered from the biliopancreatic segment with average counts of 10(4) cfu/mL and median counts of 10(5) cfu/mL. Four patients had counts of 10(7) cfu/mL. The most common aerobes were E. coli, Klebsiella, Gram-positive cocci, and Candida; among anaerobes, Clostridium and the Bacteroides fragilis group were most common. In three patients treated with metronidazole because of diarrhea, anaerobes were eliminated and diarrhea cleared.

Anaerobic bacteria. Their role in infection and their management

Anaerobic bacteria are commonly involved in a number of common infections--especially aspiration pneumonia, intraabdominal infection, and a variety of female genital tract infections. Certain distinctive clinical features suggest the possibility of anaerobic infection; included are foul odor, infection in proximity to a mucosal surface, abscess formation, and gas in tissues or discharges. Treatment includes surgical management (debridement and drainage) and use of appropriate antimicrobial agents.

Bacteriologic and clinical study of Bacteroides oris and Bacteroides buccae

We characterized clinical isolates previously identified in our laboratory as Bacteroides ruminicola, the human strains of which are now classified as Bacteroides oris and Bacteroides buccae. A total of 72 isolates (55 B. buccae isolates and 17 B. oris isolates) recovered over a 10-year period were studied. They were differentiated from each other by special-potency antibiotic disks and the RapID-ANA system. The two organisms were associated with a variety of infections, the majority being pleuropulmonary (29.2%) and infections of the head and neck region (27.8%). The infections were always polymicrobial, usually with more than five organisms per specimen. A total of 44% of the B. oris strains and 27% of the B. buccae strains were resistant to penicillin G (breakpoint, 2 U/ml), and this correlated with the presence of beta-lactamase. Although B. oris and B. buccae are found with some frequency in human infections, they are present primarily as components of a mixed flora.

Outpatient therapy of bite wounds. Demographic data, bacteriology, and a prospective, randomized trial of amoxicillin/clavulanic acid versus penicillin +/- dicloxacillin

Thirty patients received penicillin (17 of these also received dicloxacillin) and 31 received amoxicillin/clavulanic acid in a randomized study of the outpatient management of bite wounds. A wide variety of aerobic (185 strains) and anaerobic (47 strains) bacteria were isolated from these wounds. The control and study regimens were equally effective. There were four therapeutic failures in all. Aggressive wound management along with antimicrobial therapy led to a 87-96% cure rate. Loose stools or diarrhea was a more frequent side effect with amoxicillin/clavulanic acid than with penicillin +/- dicloxacillin.

Bowel flora changes in humans receiving cefixime (CL 284,635) or cefaclor

Twelve healthy young male subjects received either cefixime, a new oral cephalosporin (CL 284,635), or cefaclor (six subjects on each drug) orally for 2 weeks. In the case of cefixime, single daily doses of 400 mg were taken; with cefaclor, the dosage was 250 mg three times daily. Modest changes in the fecal flora were noted in both drug groups, but the changes were of different types. In the case of cefixime, there was more of an impact on the indigenous flora, and in the case of cefaclor, there was more ingrowth of new flora. With cefixime, Enterobacteriaceae were usually decreased (the decrease in Escherichia coli count was statistically significant), as were counts of clostridia and sometimes Bifidobacterium spp.; the Bacteroides fragilis group was eliminated in one subject. Coincident with these decreases, four subjects had increases in counts of group D streptococci of 3 logs or more. There was new appearance of Clostridium difficile in four subjects and of Staphylococcus aureus in one; four new strains of Enterobacteriaceae appeared. With cefaclor, there was no decrease of E. coli counts; two subjects had elimination of Bifidobacterium spp. There was little change in counts of group D streptococci. On the other hand, there were 13 new strains of Enterobacteriaceae, two of S. aureus, and three of C. difficile.

Chronic anaerobic bacterial endophthalmitis in pseudophakic rabbit eyes

Experimental anaerobic bacterial endophthalmitis was produced in pseudophakic and aphakic rabbits by using anterior chamber inoculation of 2.5 x 10(6) Propionibacterium acnes organisms. Clinical inflammation was more intense and prolonged in operated eyes with an intraocular lens in place. The presence of an intraocular lens favors the development of chronic low-grade P. acnes-related inflammation.

A randomized, double-blind comparison of sulbactam/ampicillin and clindamycin for the treatment of aerobic and aerobic-anaerobic infections

In a randomized, prospective, double-blind trial, sulbactam/ampicillin was compared with clindamycin in terms of efficacy and safety for the treatment of bacterial infections. Both sulbactam/ampicillin and clindamycin were given with gentamicin when this course was indicated by clinical or laboratory findings. In five patients the site of infection was pleuropulmonary; in 14, bone; in 11, skin and soft tissue; and in one, intraabdominal. The commonest anaerobes isolated were anaerobic cocci and Bacteroides species; the commonest aerobic and facultative bacteria were Enterobacteriaceae, Pseudomonas aeruginosa, and various gram-positive cocci. All of six assessable patients given sulbactam/ampicillin alone had satisfactory clinical responses, as did seven of nine patients given sulbactam/ampicillin plus gentamicin, all of six patients given clindamycin alone, and six of nine patients given clindamycin plus gentamicin. Pathogens were totally or partially eradicated in four of five, eight of nine, four of five, and three of nine assessable patients given these same regimens. Adverse reactions and laboratory abnormalities were relatively uncommon. Overall, sulbactam/ampicillin was as effective as clindamycin in the treatment of aerobic or mixed aerobic-anaerobic infections; however, the concomitant use of gentamicin was frequently required with both regimens.

In vitro activities of 17 antimicrobial agents against the formate/fumarate-requiring, anaerobic gram-negative bacilli

The in vitro activities of 17 antimicrobial agents were evaluated against 46 clinical isolates of formate/fumarate-requiring anaerobic gram-negative bacilli. Strains of Bacteroides ureolyticus (23) were almost uniformly susceptible to the tested antimicrobials, whereas strains of Bacteroides gracilis (18) showed some striking resistance with penicillin active against only 67%, the cephalosporins active against 67%-89%, and clindamycin active against 67%. Although few strains of Wolinella species/C. concisus (5) were available for testing, these isolates tended to be more resistant than B. ureolyticus but less resistant than B. gracilis.

Comparative activity of SCH 34343 against anaerobic bacteria

The in vitro activity of SCH 34343 was compared with that of imipenem, clindamycin, cefoxitin, and metronidazole against 78 strains of anaerobic bacteria in the presence and absence of blood. Wilkins-Chalgren agar was used. SCH 34343 and imipenem were the most active agents, inhibiting all strains at less than or equal to 8 micrograms/ml. The addition of blood had little effect on the activity of any of the agents. Seven strains were unable to grow on Wilkins-Chalgren agar. Even with the addition of blood, one strain each of Bacteroides asaccharolyticus and Bacteroides bivius and two strains of Fusobacterium were unable to grow. Sixty-eight of the strains were tested against SCH 34343 and imipenem on Brucella lysed blood agar. Minimal inhibitory concentrations tended to be somewhat higher on Brucella lysed blood agar than on Wilkins-Chalgren agar, and all strains were able to grow on Brucella lysed blood agar.

Susceptibility of bite wound bacteria to seven oral antimicrobial agents, including RU-985, a new erythromycin: considerations in choosing empiric therapy

The susceptibility of 93 aerobic and 59 anaerobic bacteria isolated from human and animal bite wounds was determined by agar dilution. No agent tested (penicillin, oxacillin, cephalexin, sulfamethoxazole-trimethoprim, minocycline, erythromycin, and RU-965) was consistently active against all isolates. A total of 21% of the Bacteroides species, all isolated from human bites, were resistant to penicillin; 14 and 18% of the Pasteurella multocida isolates were resistant to erythromycin and oxacillin, respectively.

Clinical considerations in the diagnosis of antimicrobial agent-associated gastroenteritis

Most gastrointestinal infections secondary to the use of antimicrobial agents that have been documented are related to overgrowth of Clostridium difficile which produces a spectrum from severe pseudomembranous colitis to mild diarrhea or asymptomatic carriage. The most common inducers of pseudomembranous colitis or antimicrobial agent-associated diarrhea are ampicillin, clindamycin, and various cephalosporins, but almost all antimicrobials may cause this problem. Symptoms vary from watery to bloody diarrhea; the extent and severity of the diarrhea, fever, and abdominal cramps and the incidence of complications (such as toxic megacolon and perforation of the bowel) and of fatality are variable. Normal carriage of C. difficile in infants and asymptomatic carriage in adults who have received antimicrobial therapy make it impossible to rely on culture for diagnosis. The presence of cytotoxin or enterotoxin produced by C. difficile is much more reliable diagnostically, but there may be false-positives with this as well, particularly in infants. However, the combination of the appropriate clinical picture and background and presence of toxin usually permit accurate diagnosis. The definitive method of diagnosis, often not feasible to employ, is demonstration by colonoscopy or sigmoidoscopy of the pathognomonic yellow, elevated plaques on the colonic mucosa. Colonoscopy is preferred since the plaques may be restricted to the right colon, particularly in early cases. From the practical standpoint, the best diagnostic test is demonstration of C. difficile toxin.

Six-year retrospective survey of the resistance of Bacteroides fragilis group species to clindamycin and cefoxitin

Two hundred and forty-six strains of the Bacteroides fragilis group, all clinical isolates, collected at the Wadsworth Veterans Administration Medical Center from 1977 to 1982, were tested for susceptibility to clindamycin and cefoxitin. There was no significant change in resistance to either clindamycin or cefoxitin over the time period tested for any individual species, nor for the B. fragilis group in toto. Striking differences in susceptibility to the two drugs were seen among species of the B. fragilis group. B. fragilis displayed resistance to cefoxitin (32 micrograms/ml) and clindamycin (8 micrograms/ml) of 0.0% and 0.8%, respectively, whereas B. thetaiotaomicron showed resistances of 12.7% to cefoxitin (32 micrograms/ml) and 9% to clindamycin (8 micrograms/ml). B. thetaiotaomicron, B. distasonis, and B. ovatus are distinctly more resistant to cefoxitin than B. fragilis and B. vulgatus. Similarly B. thetaiotaomicron and B. distasonis are much more resistant to clindamycin than are the other B. fragilis group species. It is apparent that determination of species within the B. fragilis group is important in evaluating a potential therapeutic regimen.

Bacterial agglutination and polyacrylamide gel electrophoresis for typing Clostridium difficile

Bacterial agglutination and polyacrylamide gel electrophoresis (PAGE) were methods evaluated for typing strains of Clostridium difficile. A panel of four antisera, obtained by immunizing rabbits with washed whole cells of different strains of C. difficile, produced distinctive patterns of agglutination. Ethylenediaminetetraacetate (EDTA) extracts subjected to PAGE also produced distinctive protein profiles. Excellent correlation between the two methods was observed when geographically distant isolates were typed without knowledge of their clinical origin. Both typing methods should receive further evaluation for their value as tools for epidemiological studies.

Anaerobic bacterial endophthalmitis in the rabbit

Anaerobic bacterial endophthalmitis was studied in rabbits following intravitreal injection of live Fusobacterium necrophorum. Clinical response, bacterial recovery, and histopathology were studied. An inoculum of approximately 50 organisms produced endophthalmitis in 59% of injected eyes, while 1000 or more organisms produced endophthalmitis in 100% of injected eyes. The course and severity of disease seemed to be independent of the concentration of bacteria above a minimal inoculum size. Affected eyes showed progressive endophthalmitis. Histopathologic changes corresponded to the clinical gradation of endophthalmitis, including progressive retinal necrosis.

Safety and efficacy of ticarcillin plus clavulanic acid in the treatment of infections of soft tissue, bone, and joint

The efficacy and safety of ticarcillin plus clavulanic acid in the treatment of patients with infections of soft tissue, bone, and joint were evaluated in this open study. Clinical diagnoses included osteomyelitis, soft tissue abscess or ulcer, cellulitis, bite wound, traumatic or postoperative cellulitis, necrotizing fasciitis, septic arthritis, septic bursitis, and septic thrombophlebitis. Trauma or underlying disease such as diabetes mellitus or vascular insufficiency was common (more than 50 percent) in the patient population. Clinical efficacy was evaluable in 66 patients who received 3 g of ticarcillin and 0.1 g of clavulanic acid every four or six hours for a mean of 23.4 days. A satisfactory clinical response was observed in 92 percent of the patients. Major pathogens isolated were Enterobacteriaceae, anaerobic cocci, Staphylococcus aureus, and beta-hemolytic Streptococcus. Of the 143 isolates recovered from 55 bacteriologically evaluable cases, 87 percent were eradicated by therapy. Overall, a satisfactory bacteriologic outcome occurred in 93 percent of the patients, and the pathogen(s) persisted in 7 percent. More than 98 percent of the isolates were susceptible to ticarcillin plus clavulanic acid in vitro. Emergence of resistance during therapy occurred with three strains of Pseudomonas aeruginosa. Adverse drug-related reactions required discontinuation of treatment in two patients, although other minor abnormal laboratory findings were common. These results indicate that ticarcillin plus clavulanic acid offers safe and effective therapy for infections of soft tissue, bone, and joint.

Lower respiratory tract infection

The most important lower respiratory infection is pneumonia, the fourth leading cause of death. Most cases of bronchitis are of viral etiology and are not major problems. Empyema can present an important problem in management. Although the diagnosis of pneumonia is usually relatively straightforward, the specific etiologic diagnosis remains a major problem. Availability of empyema fluid or a positive blood culture result can be helpful in making the etiologic diagnosis, but these are unavailable in most patients. Screening of sputum Gram stains under 100 X magnification is very important; there should be fewer than 10 squamous epithelial cells, more than 25 polymorphonuclear leukocytes, or both per field of this size. The major causes of pneumonia are Streptococcus pneumoniae, Mycoplasma pneumoniae, anaerobic bacteria, Staphylococcus aureus, various gram-negative aerobic or facultative bacilli and Legionella. However, many other organisms are capable of causing pneumonia, even in the immunocompetent host. Further adding to the problem is the fact that a number of different organisms are manifesting increasing resistance to antimicrobial agents. Our study with ticarcillin plus clavulanic acid included seven patients with pneumonia, one with empyema, and one with purulent tracheobronchitis. Organisms recovered from pleural fluid, transtracheal aspiration and sputum or tracheostomy aspirate included multiple anaerobes, pneumococci, S. aureus, Hemophilus influenzae, Klebsiella pneumoniae, K. ozaenae, Pseudomonas aeruginosa, Acinetobacter, Enterobacter cloacae, Proteus mirabilis, beta-hemolytic streptococci, Neisseria meningitidis and Branhamella catarrhalis. Several of the organisms were ticarcillin resistant. Eight of the patients had cures and the other patient showed improvement. Only minor side-effects were encountered--Coombs' positivity (without hemolysis), eosinophilia, drug fever and one case of questionable neutropenia.