Optimal detection of carbapenemase-producing Enterobacteriaceae from rectal samples: a role for enrichment?

BACKGROUND: Successful laboratory detection of carbapenemase-producing Enterobacteriaceae (CPE) in patient surveillance samples is a diagnostic challenge. In the absence of a reference standard for screening rectal swabs for CPE, many phenotypic, genotypic, culture- and non-culture-based assays have been proposed for identifying these bacteria. AIM: To develop and optimize a CPE screening protocol capable of identifying all frequently encountered CPE, including those producing OXA-48-like carbapenemases. METHODS: Faropenem susceptibility testing was performed on 507 presumptive CPE isolated from diagnostic samples and CPE rectal screens between March and August 2016. Results from this CPE screening method were compared to those from direct culture on mSuperCARBA™, temocillin enrichment culture, and use of an antibiotic resistance algorithm, to determine the optimal method to employ in the detection of CPE. FINDINGS: Faropenem was a poor predictor of carbapenemase production (58% true positives). The combination of a temocillin enrichment stage and interpretive reading of antibiotic resistance phenotypes improved the recovery and identification of CPE significantly (91% true positives), especially for OXA-48 producers (P = 0.03). CONCLUSION: The combination of temocillin enrichment, a selective chromogenic medium, and an antibiotic resistance-based algorithm significantly improved the detection of all CPE recovered from routine and targeted surveillance samples.

Matrix-assisted laser desorption/ionisation-time of flight mass spectrometry: rapid identification of bacteria isolated from patients with cystic fibrosis.

Despite extensive research into the diagnosis and management of cystic fibrosis (CF) over the past decades, sufferers still have a median life expectancy of less than 37 years. Respiratory tract infections have a significant role in increasing the morbidity and mortality of patients with CF via a progressive decline in lung function. Rapid identification of organisms recovered from CF sputum is necessary for effective management of respiratory tract infections; however, standard techniques of identification are slow, technically demanding and expensive. The aim of this study is to asses the suitability of matrix-assisted laser desorption/ionisation-time of flight mass spectrometry (MALDI-TOF MS) in identifying bacteria isolated from the respiratory tract of patients with CF, and is assessed by testing the accuracy of MALDI-TOF MS in identifying samples from a reference collection of rare CF strains in conjunction with comparing MALDI-TOF MS and standard techniques in identifying clinical isolates from sputum samples of CF patients. MALDI-TOF MS accurately identified 100% of isolates from the reference collection of rare CF pathogens (EuroCare CF collection). The isolate identification given by MALDI-TOF MS agreed with that given by standard techniques for 479/481 (99.6%) clinical isolates obtained from respiratory samples provided by patients with CE In two (0.4%) of 481 samples there was a discrepancy in identification between MALDI-TOF MS and standard techniques. One organism was identified as Pseudomonas aeruginosa by MALDI-TOF but could only be identified by the laboratory's standard methods as of the Pseudomonas genus. The second organism was identified as P. beteli by MALDI-TOF MS and Stenotrophomonas maltophilia by standard methods. This study shows that MALDI-TOF MS is superior to standard techniques in providing cheap, rapid and accurate identification of CF sputum isolates.

Paraproteinaemia after allo-SCT, association with alemtuzumab-based conditioning and CMV reactivation.

Paraproteinaemia following allo-SCT is common. We analysed 91 consecutive patients undergoing allo-SCT; conditioning included alemtuzumab in 42% of the patients. Paraproteinaemia incidence at 2 years was 32%. In univariate analysis paraproteinaemia was associated with unrelated donor, age, recipient seropositivity for CMV and alemtuzumab conditioning (hazard ratio (HR) 3.93, P=0.0006). Paraproteinaemia was not associated with haematological diagnosis; disease status at transplant; varicella zoster, herpes simplex or EBV serology; reduced-intensity vs myeloablative conditioning or GVHD. CMV reactivation-more frequent in alemtuzumab recipients-was associated with paraproteinaemia (HR 7.52, P<0.0001). In multivariate analysis, only increasing age (HR 1.04 per year, P=0.048) and CMV reactivation (HR 5.74, P=0.001) were significantly associated with paraproteinaemia. Alemtuzumab without CMV reactivation, however, resulted in significantly more paraproteinaemia, suggesting an effect that is independent of CMV reactivation. OS was poorer in patients with paraproteinaemia (HR 2.54, P=0.04) and relapse increased (HR 2.38, P=0.087). Paraproteinaemia was not significantly independently associated with decreased survival on multivariate analysis. Post transplant paraproteinaemia is associated with CMV reactivation, is more frequent in alemtuzumab-conditioned transplants and is not associated with improved OS.

Management of occupational exposure to hepatitis C: survey of United Kingdom practice.

We conducted a survey to assess the action taken when health care workers suffered inoculation injuries from patients who might have hepatitis C virus (HCV) infection. A substantial proportion of health care workers may be receiving inadequate follow up and existing guidelines should now be implemented in full and extended to include guidance on treatment.