High levels of resistance to fluoroquinolones among Clostridium difficile isolates in a Spanish hospital

Correlation between antibiotic resistance and clinical outcome of anaerobic infections; mini-review

In anaerobic infections, the relationship between clinical failure and antibiotic resistance is difficult to demonstrate, especially in mixed anaerobic-aerobic infections. Single isolates of anaerobes in cases of bacteraemia revealed that treatment failures were due to inappropriate therapy. We review here cases, where the empiric treatment was unsuccessful due to resistance of anaerobic bacteria to the administered agents and where the change of the antibiotic allowed the patients to be cured. Many therapeutic failures could be linked to the lack of timely detection of resistance, including heteroresistance of the anaerobes. Disk diffusion or Etest methodology may be suitable, at least for rapidly growing anaerobes, to detect both resistance and heteroresistance to antibiotics widely used for empirical therapy.

A penicillin- and metronidazole-resistant Clostridium botulinum strain responsible for an infant botulism case

The clinical course of a case of infant botulism was characterized by several relapses despite therapy with amoxicillin and metronidazole. Botulism was confirmed by identification of botulinum toxin and Clostridium botulinum in stools. A C. botulinum A2 strain resistant to penicillins and with heterogeneous resistance to metronidazole was isolated from stool samples up to 110 days after onset. Antibiotic susceptibility was tested by disc agar diffusion and MICs were determined by Etest. Whole genome sequencing allowed detection of a gene cluster composed of blaCBP for a novel penicillinase, blaI for a regulator, and blaR1 for a membrane-bound penicillin receptor in the chromosome of the C. botulinum isolate. The purified recombinant penicillinase was assayed. Resistance to β-lactams was in agreement with the kinetic parameters of the enzyme. In addition, the β-lactamase gene cluster was found in three C. botulinum genomes in databanks and in two of 62 genomes of our collection, all the strains belonging to group I C. botulinum. This is the first report of a C. botulinum isolate resistant to penicillins. This stresses the importance of antibiotic susceptibility testing for adequate therapy of botulism.

Predictors of Clostridium difficile infection severity in patients hospitalised in medical intensive care

AIM: To describe and analyse factors associated with Clostridium difficile infection (CDI) severity in hospitalised medical intensive care unit patients.

METHODS: We performed a retrospective cohort study of 40 patients with CDI in a medical intensive care unit (MICU) at a French university hospital. We include patients hospitalised between January 1, 2007 and December 31, 2011. Data on demographics characteristics, past medical history, CDI description was collected. Exposure to risk factors associated with CDI within 8 wk before CDI was recorded, including previous hospitalisation, nursing home residency, antibiotics, antisecretory drugs, and surgical procedures.

RESULTS: All included cases had their first episode of CDI. The mean incidence rate was 12.94 cases/1000 admitted patients, and 14.93, 8.52, 13.24, 19.70, and 8.31 respectively per 1000 admitted patients annually from 2007 to 2011. Median age was 62.9 [interquartile range (IQR) 55.4-72.40] years, and 13 (32.5%) were women. Median length of MICU stay was 14.0 d (IQR 5.0-22.8). In addition to diarrhoea, the clinical symptoms of CDI were fever (> 38 °C) in 23 patients, abdominal pain in 15 patients, and ileus in 1 patient. The duration of diarrhoea was 13.0 (8.0-19.5) d. In addition to diarrhoea, the clinical symptoms of CDI were fever (> 38 °C) in 23 patients, abdominal pain in 15 patients, and ileus in 1 patient. Prior to CDI, 38 patients (95.0%) were exposed to antibiotics, and 12 (30%) received at least 4 antibiotics. Fluoroquinolones, 3^rd generation cephalosporins, coamoxiclav and tazocillin were prescribed most frequently (65%, 55%, 40% and 37.5%, respectively). The majority of cases were hospital-acquired (n = 36, 90%), with 5 cases (13.9%) being MICU-acquired. Fifteen patients had severe CDI. The crude mortality rate within 30 d after diagnosis was 40% (n = 16), with 9 deaths (9 over 16; 56.3%) related to CDI. Of our 40 patients, 15 (37.5%) had severe CDI. Multivariate logistic regression showed that male gender [odds ratio (OR): 8.45; 95%CI: 1.06-67.16, P = 0.044], rising serum C-reactive protein levels (OR = 1.11; 95%CI: 1.02-1.21, P = 0.021), and previous exposure to fluoroquinolones (OR = 9.29; 95%CI: 1.16-74.284, P = 0.036) were independently associated with severe CDI.

CONCLUSION: We report predictors of severe CDI not dependent on time of assessment. Such factors could help in the development of a quantitative score in ICU’s patients.

Characterization of swine isolates of Clostridium difficile in Spain: a potential source of epidemic multidrug resistant strains?

Clostridium difficile is an emerging pathogen for humans and animals and there is concern about the possibility that livestock might serve as a reservoir of epidemic strains. In Spain, ribotype 078 is one of the most prevalent in human episodes of C. difficile infection, but the distribution of this and other ribotypes in animals is yet unknown. We present the first report on the ribotype distribution and antimicrobial susceptibility of C. difficile in swine in Spain. A total of 144 isolates were PCR ribotyped, and their MIC values for 13 antimicrobial agents were determined using the Etest. Toxins A and B production was assessed using a commercial immunoassay and, in the case of toxin B, a specific cytotoxicity test. Our results show a high prevalence of the toxigenic 078 ribotype (94.4%) and multidrug resistance (49.3%) among the studied isolates. A minority of isolates (5.6%) belonged to a mostly non-toxinogenic ribotype. All isolates were resistant to the fluoroquinolone ciprofloxacin, but susceptible to daptomycin, linezolid, meropenem, rifampicin, teicoplanin, tigecycline, metronidazole and vancomycin. Resistance to clindamycin, ertapenem, erythromycin and moxifloxacin was common (≥27.8% in all cases). Resistance rates for the different antibiotics tested were in all cases independent from the ribotype of isolates and the host's condition (diarrheic or non-diarrheic), but erythromycin and moxifloxacin resistance was associated with the geographic origin of isolates. Metronidazole heteroresistance was found among animal isolates of C. difficile. Our results highlight the role of livestock as a potential source of epidemic multidrug resistant strains in Spain.

Molecular epidemiology and resistance profiles of Clostridium difficile in a tertiary care hospital in Spain

Epidemiological surveillance of Clostridium difficile infection has gained importance in recent years as a result of the rapid spread of epidemic strains, including hypervirulent strains and strains with reduced susceptibility to antimicrobials. The molecular epidemiology and antimicrobial susceptibility of C. difficile in the reference hospital of the Balearic Islands (Spain) is reported in this study. One hundred isolates of toxigenic C. difficile from different patients were selected using rapid dual EIA screening test. All isolates were characterized through toxin profile, PCR ribotyping and, in addition, multi-locus sequence typing (MLST) was performed on fifty selected strains. MICs to metronidazole, vancomycin, erythromycin and moxifloxacin were also determined. A total of 43 different ribotypes were distinguished, with higher prevalence of ribotype 014 (34%). Twenty one per cent of the isolates expressed binary toxin and it is noteworthy that 62% of these were identified as the hypervirulent ribotype 078, the second most prevalent ribotype found in our hospital (13%). A total of 20 different sequence types (STs) were found, including a new described allele and ST. MLST data showed a clear concordance between some ribotypes and STs, mainly represented by ribotype 014/ST-2, ribotype 078/ST-11 and ribotype 001/ST-3. Phylogenetic analysis also revealed that most of the isolates were genetically related, forming a large clonal complex. Finally, ribotypes 078 (ST-11) and 001 (ST-3) were associated with higher resistance to erythromycin and to erythromycin and moxifloxacin, respectively. All these data suggest that the combination of ribotyping and MLST is a good tool for the surveillance of the changing epidemiology of C. difficile. A wide dissemination of clones has been observed in our setting, ribotype 014 (ST-2) being the most prevalent followed by the hypervirulent ribotype 078 (ST-11) and ribotype 001 (ST-3), their spread in our setting probably influenced by their higher resistance.

Clostridium difficile infection after allogeneic hematopoietic stem cell transplantation: incidence, risk factors, and outcome

Clostridium difficile (C. difficile) infection was observed in 13% of recipients after hematopoietic stem cell transplantation (HSCT), mainly in the first month posttransplantation. Risk factors were cord blood as the source of stem cells, acute graft-versus-host disease (GVHD), and total body irradiation (TBI). No association was found with an increased risk of mortality. The purpose of this study was to evaluate the incidence, risk factors, and outcome of C. difficile infection (CDI) after HSCT. We conducted a single-center, retrospective, cohort study on all patients who received an allogeneic HSCT from January 2004 to December 2007. All patients with diarrhea in the first year after HSCT were tested for the presence of C. difficile in stools. Among the 407 assessable patients, 53 presented at least 1 CDI in the first year post-HSCT. The total incidence rate was 5.6 cases of CDI per 10,000 patient-days. Fifty percent of cases were diagnosed in the first month after HSCT, and 95% occurred during the first 6 months. Fewer than 5% of patients with CDI had severe diarrhea and severe complications were never observed. TBI in the conditioning regimen, cord blood as the source of stem cells, and acute graft-versus-host disease (aGVHD) were independently associated with CDI. Six patients (11%) had a recurrence of CDI. Four patients required second-line treatment with vancomycin. With a median follow-up of 22 months, the 2-year overall survival rates were similar between patients who presented a CDI and those who did not. CDI was observed in approximately 13% of recipients after HSCT, mainly in the first month posttransplantation and was associated with CB, aGVHD, and TBI. CDI was not associated either with severe complications or with an increased risk of mortality in this large cohort of patients.