Sylvia B. Debast

Emergence of Clostridium difficile Infection Due to a New Hypervirulent Strain, Polymerase Chain Reaction Ribotype 078

BACKGROUND Since 2005, an increase in the prevalence of Clostridium difficile infection (CDI) due to polymerase chain reaction ribotype 078 has been noticed in The Netherlands. This strain has also been identified as the predominant strain in pigs and calves. METHODS CDI caused by type 078 was studied in relation to CDI caused by the hypervirulent type 027 and by types other than 027 and 078. Human and porcine isolates were further investigated and characterized by multilocus variable number tandem repeat analysis. RESULTS From February 2005 through February 2008, the incidence of type 078 among isolates obtained from 1687 patients increased from 3% to 13%. Compared with patients infected with type 027, patients infected with type 078 were younger (67.4 vs. 73.5 years; P < .01) and more frequently had community-associated disease (17.5% vs. 6.7%; odds ratio, 2.98; 95% confidence interval, 2.11-8.02); rates of severe diarrhea (38.9% vs. 40.0%) and attributable mortality (3.8% vs. 4.0%) were similar in both groups. Compared with patients infected with other types, patients infected with type 078 more frequently received fluoroquinolone therapy (29.4% vs. 19.8%; odds ratio, 2.17; 95% confidence interval, 1.06-4.44). Type 078 isolates contained genes for toxin A, toxin B, binary toxin, and a 39-base pair deletion in toxin regulator gene (tcdC), as well as a point mutation at position 184, resulting in a stop codon. Multilocus variable number tandem repeat analysis of 54 human and 11 porcine isolates revealed 4 clonal complexes containing both porcine and human isolates. CONCLUSIONS CDI due to type 078 and CDI due to type 027 present with similar severity, but CDI due to type 078 affects a younger population and is more frequently community associated. C. difficile type 078 isolates from humans and pigs are highly genetically related.

Infection control measures to limit the spread of Clostridium difficile

Clostridium difficile-associated diarrhoea (CDAD) presents mainly as a nosocomial infection, usually after antimicrobial therapy. Many outbreaks have been attributed to C. difficile, some due to a new hyper-virulent strain that may cause more severe disease and a worse patient outcome. As a result of CDAD, large numbers of C. difficile spores may be excreted by affected patients. Spores then survive for months in the environment; they cannot be destroyed by standard alcohol-based hand disinfection, and persist despite usual environmental cleaning agents. All these factors increase the risk of C. difficile transmission. Once CDAD is diagnosed in a patient, immediate implementation of appropriate infection control measures is mandatory in order to prevent further spread within the hospital. The quality and quantity of antibiotic prescribing should be reviewed to minimise the selective pressure for CDAD. This article provides a review of the literature that can be used for evidence-based guidelines to limit the spread of C. difficile. These include early diagnosis of CDAD, surveillance of CDAD cases, education of staff, appropriate use of isolation precautions, hand hygiene, protective clothing, environmental cleaning and cleaning of medical equipment, good antibiotic stewardship, and specific measures during outbreaks. Existing local protocols and practices for the control of C. difficile should be carefully reviewed and modified if necessary.

Clostridium difficile PCR ribotype 078 toxinotype V found in diarrhoeal pigs identical to isolates from affected humans

In diseased piglets from two Dutch pig-breeding farms with neonatal diarrhoea for more than a year, culture and PCR analyses identified the involved microorganism as Clostridium difficile PCR ribotype 078 harbouring toxin A (tcdA) and B (tcdB), and binary toxin genes. Isolated strains showed a 39 bp deletion in the tcdC gene and they were ermB gene-negative. A number of 11 porcine and 21 human isolated C. difficile PCR ribotype 078 toxinotype V strains were found genetically related by multiple-locus variable-number tandem-repeat analysis (MLVA). Moreover, a clonal complex was identified, containing both porcine and human isolates. The porcine isolates showed an antimicrobial susceptibility profile overlapping that of isolates from Dutch human patients. On the basis of these pheno- and genotypical analyses results, it was concluded that the strains from affected piglets were indistinguishable from increasingly encountered C. difficile PCR ribotype 078 strains of human C. difficile infections in the Dutch population and that a common origin of animal and humans strains should be considered.

Clostridium difficile PCR Ribotype 078: an Emerging Strain in Humans and in Pigs?

In a recent paper, Keel and colleagues concluded that Clostridium difficile PCR ribotype 078 was the most common PCR ribotype among isolates from swine (83% of 119 isolates) and isolates from calves (94% of 33 isolates) in The United States ([1][1]). In contrast, only 1 of 23 human isolates

Successful combat of an outbreak due to Clostridium difficile PCR ribotype 027 and recognition of specific risk factors.

In the period April-September 2005, an outbreak of Clostridium difficile infection (CDI) due to PCR ribotype 027 occurred among 50 patients in a 341-bed community hospital in Harderwijk, The Netherlands. A retrospective case-control study was performed to identify risk factors specific for CDI, using a group of patients with CDI (n = 45), a group of randomly selected control patients without diarrhoea (n = 90), and a group of patients with non-infectious diarrhoea (n = 109). Risk factors for CDI and for non-CDI diarrhoea were identified using multiple logistic regression analysis. Independent risk factors for CDI were: age above 65 years (OR 2.6; 95% CI 1.0-5.7), duration of hospitalization (OR 1.04 per additional day; 95% CI 1.0-1.1), and antibiotic use (OR 12.5; 95% CI 3.2-48.1). Of the antibiotics used, cephalosporins and fluoroquinolones were identified as the major risk factors for development of CDI. The risk of developing CDI was particularly high in people receiving a combination of a cephalosporin and a fluoroquinolone (OR 57.5; 95% CI 6.8-483.6). The main factors affecting the risk of non-CDI diarrhoea were proton-pump inhibitors, immunosuppressive drugs, underlying digestive system disease, previous surgery, and gastric tube feeding. The outbreak ended only after implementation of restricted use of cephalosporins and a complete ban on fluoroquinolones, in addition to general hygienic measures, cohorting of patients in a separate ward, education of staff, and intensified environmental cleaning. The results of this study support the importance of appropriate antimicrobial stewardship in the control of hospital outbreaks with C. difficile PCR ribotype 027.

Type-Specific Risk Factors and Outcome in an Outbreak With 2 Different Clostridium difficile Types Simultaneously in 1 Hospital

BACKGROUND Clostridium difficile infection (CDI) due to polymerase chain reaction (PCR) ribotype 027 (type 027) has been described worldwide. In some countries, an increase was reported of toxin A-negative PCR ribotype 017 (type 017). We encountered an outbreak due to these 2 types occurring simultaneously in a 980-bed teaching hospital in the Netherlands. METHODS In a case-control study from May 2005 through January 2007, we investigated general and type-specific risk factors as well as outcome parameters for CDI due to type 027 or 017. Clonal dissemination was investigated by multilocus variable number of tandem repeat analysis (MLVA). RESULTS We identified 168 CDI patients: 57 (34%) with type 017, 46 (27%) with type 027, and 65 (39%) with 1 of 36 different other types. As controls, we included 77 non-CDI diarrheal patients and 162 patients without diarrhea. Risk factors for CDI were nasogastric intubation, recent hospitalization, and use of cephalosporins and clindamycin. Type-specific risk factors were older age for both types 017 and 027, use of clindamycin and immunosuppressive agents for type 017, and use of fluoroquinolones for type 027. At day 30 of follow-up, the overall mortality among patients with types 017, 027, other types, non-CDI diarrheal patients, and nondiarrheal patients was 23%, 26%, 3%, 2%, and 6%, respectively. MLVA showed persistent clonal dissemination of types 017 and 027, despite appropriate infection control measures. CONCLUSIONS Patients with CDI have type-specific risk factors and mortality rates, with prolonged clonal spread of type 027 or 017.

Antimicrobial activity of LFF571 and three treatment agents against Clostridium difficile isolates collected for a pan-European survey in 2008: clinical and therapeutic implications

OBJECTIVES In November 2008, a study was performed with support from the European Centre for Disease Prevention and Control (ECDC) to obtain an overview of Clostridium difficile infections (CDIs) in European hospitals. A collection of 398 C. difficile isolates obtained from this hospital-based survey was utilized to identify antimicrobial susceptibility patterns of common C. difficile PCR ribotypes across Europe. METHODS The MICs of three approved therapeutic agents (vancomycin, metronidazole and fidaxomicin) and LFF571 (a novel semi-synthetic thiopeptide antibiotic) were determined by the agar dilution method. RESULTS MICs of fidaxomicin and LFF571 were in general 2-4-fold lower than those of vancomycin and metronidazole. Isolates belonging to clade 2, including the hypervirulent ribotype 027, had one-dilution higher MIC50 and MIC90 values for fidaxomicin and metronidazole, whereas similar MIC values were observed for vancomycin and LFF571. Isolates belonging to C. difficile PCR ribotype 001 were more susceptible to fidaxomicin than other frequently found PCR ribotypes 014/020 and 078. Six isolates from three different countries had a metronidazole MIC of 2 mg/L. Four of the six isolates were characterized as PCR ribotype 001. CONCLUSIONS There was no evidence of in vitro resistance of C. difficile to any of the four agents tested. However, the results suggest type-specific differences in susceptibility for the treatment agents we investigated. Continuous surveillance of C. difficile isolates in Europe is needed to determine the possible clinical implications of ribotype-specific changes in susceptibility to therapeutic agents.

Effect on diagnostic yield of repeated stool testing during outbreaks of Clostridium difficile-associated disease.

The effect on diagnostic yield of testing sequential stools was assessed during two hospital epidemics of Clostridium difficile. Using a rapid immunoassay, C. difficile-associated disease was diagnosed in 237 diarrhoeal patients, of whom 204 (86%) were diagnosed from the first faeces sample and 12 (5%) were diagnosed from follow-up samples obtained within 1 week. The remaining 21 (9%) patients yielded a positive test from stools obtained >1 week after the initial negative sample. It was concluded that repeated testing of stools for C. difficile toxin is of value in controlling outbreaks of C. difficile infection.