Occurrence of clindamycin-resistant anaerobic bacteria isolated from cultures taken following clindamycin therapy.

MICs of clindamycin were determined by the agar dilution method against anaerobic organisms isolated from endometrial cultures in women with pelvic soft tissue infections. Cultures were obtained from 100 women both before and after clindamycin therapy, from 107 women before therapy with clindamycin or another antimicrobial agent or after treatment with an antimicrobial agent other than clindamycin, and from 9 women 1 to 9 weeks after they were discharged from the hospital following clindamycin therapy. Only 5 (0.7%) of 685 isolates tested from women who had not received clindamycin therapy were resistant to clindamycin. From the 100 cultures taken immediately after clindamycin therapy, 57 anaerobic bacteria were isolated from 28 cultures. Of the 40 anaerobic organisms for which MICs of clindamycin were determined, 25 (62.5%) were resistant to clindamycin (MIC greater than or equal to 8 micrograms/ml). The most common organisms isolated after therapy were the anaerobic gram-positive cocci (of which 32 isolates were discovered); of 28 coccal isolates tested, 64% were clindamycin resistant. Four of seven (57%) of the Bacteroides isolates tested, one unidentified gram-positive nonsporing rod, one unidentified gram-negative coccus, and one Mobiluncus sp. were also clindamycin resistant. Of 18 anaerobic isolates from the nine cultures taken 1 to 9 weeks after hospital discharge, 55% were resistant to clindamycin. The clinical significance of these findings is unknown since all patients recovered without incident and remained well. However, the data suggest that physicians need to be aware that patients with recent exposure to clindamycin may have clindamycin-resistant anaerobic organisms in a current infection. This may prevent the infection from responding to clindamycin treatment.     

In-vivo protection of group A beta-haemolytic streptococci from penicillin by beta-lactamase-producing Bacteroides species

The incidence of persistent group A beta-haemolytic streptococci in tonsils, despite penicillin therapy, has increased in recent years. beta-Lactamase-producing organisms have previously been recovered from 74% of patients with persisting group A streptococci. We investigated the possibility that beta-lactamase-producing strains of Bacteroides spp. can protect streptococci from penicillin. A mixed infection was induced in mice in the form of a subcutaneous abscess involving a penicillin-susceptible group A streptococcus, and a beta-lactamase-producing strain of either Bact. melaninogenicus or Bact. fragilis. The infected animals were treated for seven days with parenteral penicillin, penicillin and clavulanic acid or clindamycin. Penicillin treatment prevented the formation of abscesses in animals inoculated with group A streptococci alone, but not in those inoculated with group A streptococci and Bacteroides spp. We attributed this resistance to penicillin therapy, and the subsequent formation of abscesses in mice, to protection of the streptococci from penicillin by beta-lactamase-producing strains of Bacteroides spp. Effective therapy for mixed infections was achieved when clavulanic acid, a beta-lactamase inhibitor, was administered with penicillin. A similar effect was noted with clindamycin, which is active against both group A streptococci and Bacteroides spp.     

Activity of fleroxacin alone and in combination with clindamycin or metronidazole in experimental intra-abdominal abscesses.

To assess the potential efficacy of fleroxacin in combination with clindamycin or metronidazole in mixed aerobic and anaerobic infections, we used a rat model of intra-abdominal abscesses in which the inoculum consisted of pooled rat feces mixed with BaSO4. Two hours after bacterial challenge, antimicrobial therapy was begun intravenously with regimens designed to stimulate human pharmacokinetics. A combination of clindamycin and gentamicin was included as an established treatment regimen. After 8.5 days of therapy, final bacterial counts in abscesses showed that fleroxacin alone or combined with metronidazole or clindamycin effectively eradicated Escherichia coli, with bacterial densities of < or = 2.84 +/- 0.1, < or = 2.9 +/- 0.1, and < or = 2.9 +/- 0.1 (mean +/- standard error of the mean) log10 CFU/g, respectively. The addition of either clindamycin or metronidazole to fleroxacin substantially enhanced the effectiveness of the regimens against Bacteroides fragilis, with bacterial counts of < or = 3.0 +/- 0.1 or < or = 2.9 +/- 0.1 log10 CFU/g, respectively, versus 9.2 +/- 0.2 log10 CFU/g for fleroxacin alone. The combination of metronidazole and fleroxacin also resulted in a significantly greater reduction of peptostreptococci and Bacteroides thetaiotaomicron than fleroxacin alone (< or = 2.9 +/- 0.1 versus 6.1 +/- 0.9 log10 CFU/g and 3.3 +/- 0.4 versus 8.3 +/- 0.1 log10 CFU/g, respectively). Except for those of B. fragilis, counts of other anaerobes were reduced to a greater extent by metronidazole plus fleroxacin than by clindamycin plus fleroxacin, although differences were not always significant. Metronidazole plus fleroxacin was at least as active a clindamycin plus gentamicin against all species and was significantly more active against Clostridium spp. No regimen effectively eradicated enterococci from the abscesses. These results suggest that the addition of either metronidazole or clindamycin would effectively enhance the spectrum of fleroxacin for treatment of mixed aerobic and anaerobic infections.     

Treatment of Anaerobic Bacterial Infections with Clindamycin-2-Phosphate

Thirty-five patients with a variety of serious infections caused by anaerobic bacteria responded to clindamycin. Cure was achieved in 27 of the 32 patients with pleuropulmonary and intra-abdominal infections. Mean serum concentrations of clindamycin for the 8 h after intramuscular administration of clindamycin in these patients were at least 2.5 times the minimal inhibitory concentration of clindamycin for more than 90% of anaerobes. This experience suggests that clindamycin is an excellent and relatively safe antibiotic for treatment of infection caused by anaerobes when combined with surgery (when indicated) or other antibiotics active against aerobic gram-negative bacilli, if present.     

Susceptibilities of bovine summer mastitis bacteria to antimicrobial agents.

The susceptibility to 9 antimicrobial agents of 32 aerobic bacterial isolates and to 10 antimicrobial agents of 37 anaerobic bacterial isolates from 23 cases of bovine summer mastitis (16 Actinomyces pyogenes isolates, 8 Streptococcus dysgalactiae isolates, 3 S. uberis isolates, 3 S. acidominimus isolates, 2 Streptococcus spp., 15 Peptostreptococcus indolicus isolates, 10 Fusobacterium necrophorum isolates, and 12 isolates of anaerobic gram-negative rods) was determined by the agar dilution method. All isolates except one Bacteroides fragilis isolate (beta-lactamase producer) were susceptible to penicillin G, amoxicillin, amoxicillin-clavulanate, cefoxitin, clindamycin, and chloramphenicol (the B. fragilis strain was susceptible to the last four), which had MICs at which 90% of isolates were inhibited (MIC90s) of < or = 0.06, < or = 0.06, < or = 0.06 0.25, < or = 0.06, and 4.0 micrograms/ml, respectively. Spiramycin was active against the gram-positive aerobes (MIC90, 1.0 microgram/ml) but not against the anaerobes (MIC90, 16.0 micrograms/ml). Similar trends were noted for susceptibilities of aerobic and anaerobic bacteria to ofloxacin (MIC90s, 2.0 and 8 micrograms/ml, respectively). Occasional strains of aerobic streptococci were resistant to oxytetracycline, but all anaerobes were susceptible. Tinidazole was active against all anaerobes (MIC90, 2.0 micrograms/ml). beta-Lactamase was produced only by the B. fragilis isolate.     

Tetracyclines, chloramphenicol, erythromycin, and clindamycin

The tetracyclines are effective in the treatment of Chlamydia, Mycoplasma pneumoniae, and rickettsial infections and may also be used for gonococcal infections in patients unable to tolerate penicillins. These drugs may cause gastrointestinal irritation, photo-toxic dermatitis, diarrhea, vestibular damage, and hepatotoxicity in pregnant women. Chloramphenicol is used primarily for anaerobic infections, Haemophilus influenzae meningitis, and typhoid fever. The most important toxic effect of chloramphenicol is bone marrow suppression, which can be dose related or idiosyncratic. Erythromycin is the drug of choice for the treatment of infections caused by M. pneumoniae, Legionella species, group A beta-hemolytic streptococci, and Streptococcus pneumoniae. The frequency of serious untoward effects associated with the use of erythromycin is low; epigastric distress may occur. Clindamycin is active against Bacteroides fragilis and other anaerobic microorganisms. Pseudomembranous enterocolitis has developed in as many as 10% of patients taking this drug. The use of clindamycin should be discontinued promptly if diarrhea occurs.     

Evaluation of the in vitro activity of NVP-LMB415 against clinical anaerobic isolates with emphasis on the Bacteroides fragilis group

OBJECTIVES: To compare the in vitro activity of NVP-LMB415 (formerly referred to as NVP-PDF 713) with that of other agents with anti-anaerobe activity against clinical anaerobic isolates, with emphasis on the Bacteroides fragilis group. METHODS: The MICs for 405 B. fragilis group and 102 Gram-positive anaerobic isolates were determined using NCCLS-recommended procedures. The activity of NVP-LMB415 was compared with that of cefoxitin, clindamycin, imipenem, garenoxacin, linezolid, moxifloxacin and tigecycline. Vancomycin was included in the evaluation of the Gram-positive organisms. RESULTS: NVP-LMB415 showed excellent in vitro activity against all the species of the B. fragilis group isolates (MIC range < or = 0.03-0.5 mg/L and MIC(90) 0.5 mg/L). NVP-LMB415 was active against B. fragilis group strains resistant to beta-lactams, quinolones or clindamycin, and the MICs were much lower than those of newer agents such as linezolid, tigecycline and garenoxacin. The MICs of NVP-LMB415 ( > or = 4 mg/L) for Clostridium species were higher than the MICs for other anaerobes. CONCLUSIONS: Given the frequency of isolation of anaerobic bacteria and their increasing resistance to all classes of antibiotics, NVP-LMB415 is an ideal agent for potential use against mixed infections caused by resistant anaerobic pathogens such as of B. fragilis and Gram-positive aerobic strains such as methicillin-resistant staphylococci, streptococci and enterococci.     

In vivo efficacies of quinolones and clindamycin for treatment of infections with Bacteroides fragilis and/or Escherichia coli in mice: correlation with in vitro susceptibilities.

Therapy with ofloxacin, ciprofloxacin, and lomefloxacin (alone or in combination with clindamycin) and therapy with sparfloxacin, clinafloxacin, and temafloxacin alone were given to mice with subcutaneous abscesses. The abscesses were caused by two Bacteroides fragilis isolates, one of which was susceptible and one of which was resistant to ofloxacin, ciprofloxacin, and lomefloxacin, alone or in combination with Escherichia coli. The abscesses were examined 5 days after inoculation. Numbers of B. fragilis organisms reached log10 10.2 to 11.8 per abscess, and numbers of E. coli organisms reached log10 10.6 to 11.8 per abscess. All of the quinolones reduced the number of susceptible B. fragilis isolates (log10 3.6 to 6.9) and E. coli isolates (log10 5.7 to 6.8). However, ciprofloxacin and lomefloxacin failed to reduce the number of resistant B. fragilis organisms in single-organism or mixed infections. The addition of clindamycin to either ofloxacin, ciprofloxacin, or lomefloxacin reduced the numbers of both susceptible and resistant B. fragilis organisms (log10 3.8 to 7.8). In contrast, sparfloxacin, clinafloxacin, and temafloxacin were effective as single therapy in eradicating B. fragilis resistant to ofloxacin, ciprofloxacin, and lomefloxacin. These in vivo data confirm the in vitro activity of these quinolones and suggest that although ofloxacin, ciprofloxacin, and lomefloxacin are occasionally effective as single agents in eradicating mixed infection by susceptible strains of B. fragilis and E. coli, addition of an agent with activity against anaerobic organisms will ensure their efficacy. Quinolones with good efficacy against B. fragilis may be effective as single-agent therapy of mixed infections.     

Therapeutic efficacy of moxifloxacin, a new quinolone, in the treatment of experimental intra-abdominal abscesses induced by Bacteroides fragilis in mice

Moxifloxacin, a new quinolone, is effective in vitro against several anaerobic bacteria including Bacteroides fragilis, but its in vivo activity against anaerobic infections is not known. In this study, we evaluated the in vivo activity of moxifloxacin in the treatment of experimentally induced intra-abdominal abscesses (IAA) caused by B. fragilis. For comparison, clindamycin, metronidazole, and levofloxacin were used, and saline for control. Absence of bacteria (sterile) in the abscess pus was required to call it a cure. Mice were intraperitoneally injected with B. fragilis plus sterile rat feces and barium sulfate. Animals were treated with moxifloxacin (40 mg/kg/b.i.d.), clindamycin (75 mg/kg/b.i.d.), levofloxacin (40 mg/kg/b.i.d.) or metronidazole (75 mg/kg/b.i.d.) for 10 days. The cure rate was 12% in controls on saline therapy, 57% on metronidazole, 67% on levofloxacin, 73% on moxifloxacin and 79% on clindamycin. The therapeutic efficacy of moxifloxacin in this B. fragilis infection was not significantly different from that observed with clindamycin. By virtue of its established efficacy on gram-negative aerobic bacteria and the observed in vivo efficacy on B. fragilis, moxifloxacin can be evaluated in the treatment of clinical anaerobic infections.     

Effect of amoxicillin and co-amoxiclav on the aerobic and anaerobic nasopharyngeal flora

The effects of co-amoxiclav (AMC) and amoxicillin (AMX) therapy on the nasopharyngeal flora of children with acute otitis media (AOM) were compared. Nasopharyngeal culture for aerobic and anaerobic bacteria were obtained before therapy and 2-4 days after completion of antimicrobial therapy in 25 patients treated with either antibiotic. After therapy, 16 (64%) of the 25 patients treated with AMX and 23 (92%) of the 25 patients treated with AMC were considered clinically cured. Polymicrobial aerobic-anaerobic flora were present in all instances. A significant reduction in the number of both aerobic and anaerobic isolates occurred after therapy in those treated with AMX (177 isolates versus 133, P< 0.005) and AMC (172 isolates versus 60, P< 0.001). However, the number of all isolates recovered after therapy in those treated with AMC was significantly lower (60 isolates) than in those treated with AMX (133 isolates, P < 0.001). The recovery of known aerobic pathogens (e.g. Streptococcus pneumoniae, Staphylococcus aureus, beta-haemolytic streptococci, Haemophilus species and Moraxella catarrhalis) and penicillin-resistant bacteria after therapy was lower in the AMC group than in the AMX group (P < 0.005). This study illustrates the greater ability of AMC, compared with AMX, to reduce the number of potential nasopharyngeal pathogens and penicillin-resistant bacteria in children with AOM.     

Aerobic and anaerobic microbiology of intra-abdominal abscesses in children

In this study of the aerobic and anaerobic microbiology of 23 intra-abdominal abscesses, aerobic bacteria alone were present in one specimen, anaerobic bacteria only in four, and mixed aerobic and anaerobic flora in 18. Ninety bacterial isolates (3.9 isolates per specimen), 63 anaerobic (2.7 per specimen), and 27 aerobic and facultative (1.2 per specimen) isolates were recovered. The predominant organisms were Bacteroides fragilis group (23 isolates), Peptostreptococcus sp (20 isolates), and Escherichia coli (15 isolates). This study demonstrates the polymicrobial aerobic-anaerobic etiology of intra-abdominal abscesses in children.     

Antimicrobial susceptibilities of anaerobic bacteria isolated from female genital tract infections.

Certain species or subspecies of anaerobic bacteria are isolated with higher frequency from female genital tract infections than from other anatomic sites. To gain susceptibility data more specific to the treatment of these infections, nine antimicrobial agents were tested by an agar dilution technique against 230 anaerobic bacteria isolated solely from obstetric and gynecological infections. These genital isolates were, in general, very susceptible to imipenem (most active, inhibiting all gram-negative rods at less than or equal to 1 microgram/ml), clindamycin (all isolates inhibited at less than or equal to 4 micrograms/ml), metronidazole (all gram-negative rods inhibited at less than or equal to 4 micrograms/ml), and chloramphenicol. Penicillin G had generally low activity against Bacteroides spp., not restricted to just the Bacteroides fragilis group, although it was very active against gram-positive species. Bacteroides bivius, a species uniquely common in female genital infections, was particularly resistant (90% MIC, 64 U/ml). Also, the Bacteroides melaninogenicus isolates were less susceptible than previously reported for isolates not exclusively from genital sites. Compared with moxalactam, cefotaxime, and cefoperazone, cefoxitin usually demonstrated equal or greater activity against most Bacteroides spp., with the exception of greater activity of moxalactam against B. fragilis (formerly subsp. fragilis). Resistance to moxalactam was observed among strains of Peptostreptococcus anaerobius, a common genital isolate. Overall, the activities of these four drugs were not as predictable as those observed for clindamycin, metronidazole, chloramphenicol, and imipenem.     

Comparative in vitro antimicrobial activity of a novel quinolone, garenoxacin, against aerobic and anaerobic microbial isolates recovered from general, vascular, cardiothoracic and otolaryngologic surgical patients

OBJECTIVES: The aim of the study was to analyse the susceptibility of unique and non-duplicate aerobic and anaerobic isolates from surgical patients to a novel des-F(6)-quinolone (garenoxacin) and other selected antimicrobial agents. METHODS: Eleven hundred and eighty-five aerobic and anaerobic isolates from general, vascular, cardiothoracic and otolaryngologic surgical patients were tested for susceptibility to garenoxacin and seven other antibiotics (ciprofloxacin, moxifloxacin, levofloxacin, piperacillin/tazobactam, imipenem, clindamycin and metronidazole) using the referenced microbroth and agar-dilution method. RESULTS: Garenoxacin exhibited greater antimicrobial activity than comparator quinolones such as ciprofloxacin, levofloxacin and other antimicrobials when tested against selected gram-positive organisms. The in vitro aerobic and anaerobic activity of garenoxacin was similar to that of moxifloxacin. All fluoroquinolones tested were effective against most gram-negative facultative anaerobes including Escherichia coli. Garenoxacin and moxifloxacin demonstrated similar in vitro antimicrobial activity against selected anaerobic gram-positive and gram-negative anaerobic bacteria such as members of the Bacteroides fragilis group. Overall, the in vitro activity of the advanced spectrum quinolones against anaerobic surgical isolates compared favourably with selected comparator agents, metronidazole, imipenem and piperacillin/tazobactam. CONCLUSIONS: These findings suggest that 82.4% of aerobic surgical isolates were susceptible to a concentration of garenoxacin < or = 1.0 mg/L, whereas 84.5% of the anaerobic isolates were susceptible to a garenoxacin concentration < or = 1.0 mg/L. Garenoxacin may be a valuable surgical anti-infective for treatment of serious head and neck, soft tissue, intra-abdominal and diabetic foot infections.     

Failure of Clindamycin To Eradicate Infection with Beta-Hemolytic Streptococci Inducibly Resistant to Clindamycin in an Animal Model and in Human Infections

Inducible clindamycin resistance in beta-hemolytic streptococci remains an underrecognized phenomenon of unknown clinical significance. We performed an evaluation of inducible clindamycin resistance using an animal model as well as retrospectively reviewing the charts of patients treated with clindamycin monotherapy who were infected with beta-hemolytic streptococci inducibly resistant to clindamycin. The neutropenic mouse thigh model of infection was used to evaluate the in vivo activity of clindamycin against beta-hemolytic streptococci, including isolates susceptible, inducibly resistant, or constitutively resistant to clindamycin. The clinical microbiology laboratory information system and pharmacy databases were cross-referenced to identify patients with infections due to inducibly clindamycin-resistant beta-hemolytic streptococci who were treated with clindamycin monotherapy. Medical records of these patients were reviewed to evaluate microbiologic and clinical outcomes. Inducible clindamycin resistance resulted in impaired killing of beta-hemolytic streptococci in the animal model. Though suppressed initially, compared to those with constitutive resistance (P = 0.0429), by 48 h, colony counts of inducibly clindamycin-resistant organisms were similar to those of constitutively resistant isolates (P = 0.1142). In addition, we identified 8 patients infected with inducibly clindamycin-resistant beta-hemolytic streptococci who experienced clinical and microbiologic failure when treated with clindamycin monotherapy. These patients either improved initially and subsequently failed or never responded to clindamycin therapy. We have demonstrated in a murine model of infection and from human cases that inducible clindamycin resistance in beta-hemolytic streptococci is clinically significant. Routine testing and reporting by clinical laboratories should be encouraged and alternative antimicrobial agents considered when these organisms are encountered in clinical care.     

Clinical evaluation of moxalactam.

Moxalactam was administered intravenously or intramuscularly or both in doses of 1 to 12 g/day to 45 patients with clinically significant infections (17 soft tissue or bone, 9 pleuropulmonary, 9 septicemic, 6 urinary tract, and 4 intraabdominal infections). Mean 0.5-h postinfusion levels were 105 micrograms/ml for a 4.0-g dose, 44.7 micrograms/ml for a 2.0-g dose, and 18 micrograms/ml for a 1.0-g dose. We identified 28 isolates of Enterobacteriaceae, 10 Pseudomonas aeruginosa isolates, 9 Staphylococcus aureus isolates, and 15 anaerobic bacterial isolates. A total of 15 patients were clinically cured, 8 patients improved, 13 patients improved initially but suffered subsequent relapses or superinfections, and 10 patients failed therapy. Toxicity was generally minimal (reversible eosinophilia, and mild liver function abnormalities, and elevated prothrombin time). The selection or emergence of resistant organisms in 17 patients during treatment (particularly Pseudomonas, enterococci, and Candida) was a disturbing feature of therapy. Our results were generally favorable, considering the complicated underlying medical problems of this group of patients.     

Tetracyclines, chloramphenicol, erythromycin, clindamycin, and metronidazole.

The tetracyclines are effective in the treatment of Chlamydia, Mycoplasma pneumoniae, and rickettsial infections and also can be used for gonococcal infections in patients unable to tolerate penicillin. These drugs may cause gastrointestinal irritation, diarrhea, phototoxic dermatitis, and vestibular damage, and fatal reactions due to hepatotoxicity have occurred in pregnant women. Chloramphenicol has a broad spectrum of bacteriostatic activity, but its association with suppression of the bone marrow and aplastic anemia has relegated it to a historical role. Erythromycin is the drug of choice for the treatment of infections caused by M. pneumoniae, Legionella species, group A beta-hemolytic streptococci, and Streptococcus pneumoniae. The frequency of serious adverse effects associated with the use of erythromycin is low; dose-related epigastric distress may occur. Clindamycin is bactericidal to most nonenterococcal gram-positive aerobic bacteria and many anaerobic microorganisms. Although historically it was a frequent cause of antibiotic-associated diarrhea and colitis, clindamycin is considered an excellent alternative to beta-lactam antibiotics for treatment of many staphylococcal infections, and it has therapeutic utility in anaerobic infections and in several protozoan infections in immunosuppressed patients. Metronidazole is efficacious for treating nonpulmonary anaerobic infections, various parasitic infections (trichomoniasis, amebiasis, and giardiasis), nonspecific vaginitis, and Clostridium difficile-mediated colitis. With use of metronidazole, mild side effects such as epigastric discomfort, diarrhea, reversible neutropenia, and allergic-type cutaneous reactions may occur.     

Pharmacokinetics and serum bactericidal activities of quinolones in combination with clindamycin, metronidazole, and ornidazole.

To enhance the antimicrobial spectrum of the quinolones against anaerobic organisms and gram-positive bacteria, we investigated in two studies the parenteral combinations of ciprofloxacin (200 mg) and ofloxacin (200 mg) with metronidazole (500 mg) or clindamycin (600 mg) and the oral combinations of enoxacin (400 mg) and fleroxacin (400 mg) with metronidazole (400 mg), clindamycin (300 mg), or ornidazole (500 mg) (only with fleroxacin). The pharmacokinetics and serum bactericidal activities (SBAs) against 5 aerobic and 2 anaerobic species (total, 58 strains) were determined in two groups of 10 healthy volunteers by using a randomized crossover study design. The additions of metronidazole, clindamycin, and ornidazole did not affect the pharmacokinetics of the quinolones. The combination of clindamycin with ciprofloxacin, ofloxacin, and, to a lesser extent, fleroxacin resulted in an increase of the SBA against gram-positive strains (mean peak titers): Staphylococcus aureus, ciprofloxacin alone, 1:5.5; ciprofloxacin-clindamycin, 1:19.9; ofloxacin alone, 1:3.6; ofloxacin-clindamycin, 1:17.5; fleroxacin alone, 1:4.3; fleroxacin-clindamycin, 1:8.1; Streptococcus pneumoniae (fleroxacin and enoxacin were not tested), ciprofloxacin alone, 1:2.0; ciprofloxacin-clindamycin, 1:53; ofloxacin alone, 1:2.6; and ofloxacin-clindamycin, 1:49.2. The high SBA of quinolones against gram-negative bacteria was not affected by the combinations; however, relatively low activities against Pseudomonas aeruginosa were detected. In general, against anaerobic bacteria, low bactericidal activities were determined in both studies (mean peak titers ranged from 1:2.1 to 1:3.1; mean trough titers range from 1:2.0 to 1:2.9). In clinical settings with severe mixed infections, a parenteral therapy consisting of modern quinolones together with clindamycin or imidazole derivatives seems to be active and offers no obvious interactions.     

Clindamycin versus ampicillin in the treatment of odontogenic infections

The subjects were 106 patients, aged 14 to 70 years, with acute facial or oral abscesses originating from an odontogenic source. They were randomly assigned to receive 150 mg of clindamycin or 250 mg of ampicillin orally four times daily for seven days. After seven days of treatment, the infections were eradicated in 36 of the 52 clindamycin-treated patients and in 42 of the 54 ampicillin-treated patients, and improved in 16 and 11, respectively. One of the ampicillin group was a treatment failure. Mixed bacterial infections were found in most of the patients; 385 isolates were identified, 167 aerobes and 218 anaerobes. The most common aerobes were Staphylococcus aureus (in 58 patients), Staphylococcus epidermidis (in 47), and Staphylococcus viridans (in 32); the most common anaerobes were species of Peptococcus (in 76), Bacteroides (in 38), and Peptostreptococcus (in 33). No isolates were resistant to clindamycin; nine of 126 aerobes and six of 160 anaerobes were resistant to ampicillin. It is concluded that clindamycin is a safe and effective alternative antibiotic in the treatment of odontogenic infections.     

In-vitro activity of pristinamycin and its components against gram-negative anaerobic bacilli and Gardnerella vaginalis

The comparative in-vitro activities of pristinamycin, its components pristinamycins I and IIA, erythromycin, clindamycin and metronidazole were studied against 174 clinical isolates of Gram-negative anaerobic bacilli and 24 strains of Gardnerella vaginalis. Susceptibilities were determined with an agar-dilution method. Against Bacteroides and Fusobacterium, pristinamycin was slightly less active than both clindamycin and metronidazole and more active than erythromycin. Against G. vaginalis, the activity of pristinamycin was similar to that of clindamycin and slightly inferior to that of erythromycin. Both pristinamycins I and IIA alone were generally inactive against the strains tested. Additionally, MICs for the B. fragilis group determined by a broth microdilution technique were one to two log2 lower than MICs obtained by agar-dilution. The bactericidal activity of pristinamycin and clindamycin was moderate and varied according to the strains tested. The chequerboard broth microdilution test against 20 strains of the B. fragilis group confirmed the synergy between pristinamycins I and IIA at every PI/PIIA ratio. Along with the activity against Neisseria gonorrhoeae, Chlamydia trachomatis, Mycoplasma and both aerobic and anaerobic Gram-positive bacteria, our results suggest that pristinamycin could be an effective drug in the treatment of gynaecological infections.     

Clinical evaluation of mezlocillin.

The safety and efficacy of intravenous mezlocillin were determined in 25 patients with aerobic, anaerobic, and mixed infections. Included were pleuropulmonary, urinary tract, skin, and soft-tissue infections, osteomyelitis, and abdominal and breast abscess. Nineteen patients (76%) were cured without recurrence as determined by clinical and bacteriological parameters. In three, the infection recurred (12%); two patients failed (8%), and in one, it was indeterminate (4%). No serious adverse effects were noted except for severe thrombophlebitis in three (12%) patients. Our preliminary data suggest that mezlocillin is a safe (except for thrombophlebitis) and effective antibiotic in the treatment of aerobic anaerobic, and mixed infections.