Bacteremia with a large clostridial toxin-negative, binary toxin-positive strain of Clostridium difficile

Bacteremia caused by Clostridium difficile is rare. In this report, we describe a case of C. difficile bacteremia caused by an unusual strain of C. difficile. The isolate contained neither toxin A nor B genes, however, binary toxin genes were present (tcdA(-), tcdB(-), cdtA(+), cdtB(+)) and a 7.2-kb element unrelated to the PaLoc was found inserted within the PaLoc integration site. The clinical relevance of the isolate could not be determined.

Isolates of Clostridium perfringens recovered from Costa Rican patients with antibiotic-associated diarrhoea are mostly enterotoxin-negative and susceptible to first-choice antimicrobials

To assess the prevalence of enterotoxigenic Clostridium perfringens among adults suffering from antibiotic-associated diarrhoea in a Costa Rican hospital, faecal samples were analysed from 104 patients by a cultivation approach. The 29 strains obtained, which accounted for an isolation frequency of 28 %, were genotyped and investigated with regard to their in vitro susceptibility to penicillin, imipenem, cefotaxime, chloramphenicol and metronidazole using an agar-dilution method. A multiplex PCR for detection of the toxins α, β and ϵ predictably classified all faecal isolates as biotype A. An agglutination assay revealed that only one isolate synthesized detectable amounts of enterotoxin (detection rate 3 %). This result was confirmed by a PCR targeting the cpe gene. The spores of the only CPE+ isolate did not germinate after incubation for 30 min at temperatures above 80 °C. Most isolates were susceptible to first-choice antimicrobials. However, unusual MICs for penicillin (16 μg ml−1) and metronidazole (512 μg ml−1) were detected in one and three isolates, respectively. The low incidence of enterotoxigenic strains suggests that C. perfringens was not a major primary cause of antibiotic-associated diarrhoea in this hospital during the sampling period.

Synthesis and antibacterial activity of 1H-pyrazolo[3,4-b]pyrazine and -pyridine derivatives

The investigations of new pyrazine and pyridine derivatives showing an antibacterial activity have been made. Upon treatment of 3-chloro-2-cyanopyrazine [1] and 2-chloro-3-cyanopyridine with 1,1-dimethyl-hydrazine, 1-aminopiperidine and 1-amino-4-methylpiperazine, either the pyrazolo-pyrazine (1), and -pyridine (2) derivatives, or ammonium salts (3-8) were obtained, according to the reaction conditions. Compound 1 was obtained in the reaction of the initial nitrile with methylhydrazine as well. The reactions of 1 gave the following derivatives: acylation-(9), that with p-chlorobenzoic aldehyde-(10), and with phenyl-isothiocyanate-(11). 3-Chloro-2-cyanopyrazine treated with hydrazine hydrate gave amidrazone (12), which upon condensation with p-chlorobenzoic aldehyde produced (13). The compounds obtained were tested in vitro for their tuberculostatic activity. The minimal inhibitory concentration (MIC) values were within 22-100 microg/cm3. Compounds 1, 5 and 6 were also tested in vitro for their activity towards 25 strains of anaerobic, and 25 strains of aerobic bacteria. They appeared to be of elevated activity towards the anaerobes and of low one towards the aerobes (Table 2).

Gatifloxacin in community-acquired respiratory tract infection

Gatifloxacin (Tequin, Kyorin Pharmaceutical Co. Ltd) is a new fluoroquinolone with a broad spectrum of activity for pathogens implicated in community-acquired respiratory tract infections, including Gram-positive, -negative and atypical bacteria. Excellent oral bioavailability, a half-life allowing once-daily administration and excellent penetration into respiratory tissues are desirable pharmacokinetic characteristics of gatifloxacin. Monte Carlo simulation of gatifloxacin in Streptococcus pneumoniae infection demonstrates that adequate levels of pharmacokinetic/pharmacodynamic parameters are obtained with gatifloxacin in almost all instances. In randomised, controlled trials and a large open-label, community-based study, gatifloxacin has shown excellent clinical and bacteriological efficacy in acute bacterial sinusitis, acute exacerbations of chronic bronchitis and community-acquired pneumonia. Current guidelines recommend the initial empiric use of gatifloxacin (along with the other new fluoroquinolones) for community-acquired respiratory tract infection in patients who have increased likelihood of infection with resistant pathogens. Another group of patients where this agent is recommended for initial antimicrobial therapy are those who, because of underlying disease and/or comorbid conditions, need an antibiotic with high antimicrobial efficacy to achieve optimal outcomes.

Survey of antimicrobial susceptibility patterns of the bacteria of the Bacteroides fragilis group isolated from the intestinal tract of children

The bacteria of the Bacteroides fragilis group are considered important clinical pathogens and they are the most common anaerobes isolated from human endogenous infections. In this study, the susceptibility patterns to antibiotics and metals of 114 species of the B. fragilis group isolated from children with and without diarrhea were determined. Susceptibility was assayed by using an agar dilution method with Wilkins-Chalgren agar. All B. fragilis strains were resistant to lead and nickel, but susceptible to metronidazole and imipenem. beta-lactamase production was detected by using biological and nitrocefin methods, respectively, in 50% and 90.6% of the isolates of children with diarrhea and in 60% and 90% of the isolates of children without diarrhea. Our results show an increase of antibiotics and metals resistance in this microbial group, and a periodic evaluation of the antimicrobial susceptibility is needed. In Brazil, the contamination for antibiotics or metal ions is often observed, and it is suggested an increase the antimicrobial resistance surveillance of this microbial group, mainly those isolated from children's diarrhea.

Cytotoxicity and antimicrobial susceptibility of Clostridium difficile isolated from hospitalized children with acute diarrhea

Clostridium difficile is an important pathogen associated with outbreaks of pseudomembranous colitis and other intestinal disorders such as diarrhea. In this study, 181 stool samples from children with and without acute diarrhea were analysed. Eighteen children with acute diarrhea were positive to C. ramosum, C. difficile, C. limosum, C. clostridioforme, C. septicum, C. butyricum, C. innocuum and Clostridium sp. Nineteen children without diarrhea harbored C. ramosum, C. septicum, C. barattii, C. butyricum, C. innocuum, C. sphenoides, C. bifermentans, C. clostridioforme and C. paraputrificum. No patient with diarrhea harbored C. barattii, C. bifermentans, C. paraputrificum and C. sphenoides. In addition, ten C. difficile strains were detected in 5 (5.5%) of the children with diarrhea. Also, no children from control group harbored C. difficile, C. limosum and Clostridium sp. Most of the tested strains were resistant to all the used antimicrobial. Nine C. difficile were toxigenic on VERO cells and by multiplex PCR, six strains showed both toxin A and B genes and three strains showed only toxin B gene. In this study, the presence of C. difficile was not significant, and it is suggested the need of more studies to evaluate the role of clostridia or C. difficile play in the childhood diarrhea and these organisms must be looked for routinely and a periodic evaluation of antimicrobial susceptibility should be performed.

Antimicrobial susceptibility of Bacteroides fragilis group isolates in Europe

OBJECTIVE

To evaluate the activity of old and newer antianaerobic drugs against clinical isolates of Bacteroides fragilis group strains from different parts of Europe.

METHODS

Bacteroides fragilis group isolates from 37 laboratories in 19 countries were biochemically characterized. The MICs of seven antimicrobial agents were determined by the agar dilution method as recommended by the NCCLS. Production of beta-lactamase was detected by nitrocefin.

RESULTS

There were 1284 B. fragilis group isolates included in the study. Abdominal infections and wounds were the most common sources of isolation and B. fragilis was the dominating species. Ninety-nine percent of the strains were resistant to ampicillin (breakpoint 2 mg/L), 6% to cefoxitin (64 mg/L), 15% to clindamycin (8 mg/L) and 9% to moxifloxacin (8 mg/L). Less than 1% were resistant to imipenem (16 mg/L), piperacillin-tazobactam (128 mg/L) and metronidazole (32 mg/L). Ninety-six percent of the isolates were beta-lactamase producers.

CONCLUSIONS

Antimicrobial resistance among the B. fragilis group is increasing.