A prospective surveillance study to determine the prevalence of 16S rRNA methyltransferase-producing Gram-negative bacteria in the UK.

OBJECTIVES: To determine the prevalence of 16S rRNA methyltransferase- (16S RMTase-) producing Gram-negative bacteria in patients in the UK and to identify potential risk factors for their acquisition. METHODS: A 6 month prospective surveillance study was conducted from 1 May to 31 October 2016, wherein 14 hospital laboratories submitted Acinetobacter baumannii, Enterobacterales and Pseudomonas aeruginosa isolates that displayed high-level amikacin resistance according to their testing methods, e.g. no zone of inhibition with amikacin discs. Isolates were linked to patient travel history, medical care abroad, and previous antibiotic exposure using a surveillance questionnaire. In the reference laboratory, isolates confirmed to grow on Mueller-Hinton agar supplemented with 256 mg/L amikacin were screened by PCR for 16S RMTase genes armA, rmtA-rmtH and npmA, and carbapenemase genes (blaKPC, blaNDM, blaOXA-48-like and blaVIM). STs and total antibiotic resistance gene complement were determined via WGS. Prevalence was determined using denominators for each bacterial species provided by participating hospital laboratories. RESULTS: Eighty-four isolates (44.7%), among 188 submitted isolates, exhibited high-level amikacin resistance (MIC >256 mg/L), and 79 (94.0%) of these harboured 16S RMTase genes. armA (54.4%, 43/79) was the most common, followed by rmtB (17.7%, 14/79), rmtF (13.9%, 11/79), rmtC (12.7%, 10/79) and armA + rmtF (1.3%, 1/79). The overall period prevalence of 16S RMTase-producing Gram-negative bacteria was 0.1% (79/71 063). Potential risk factors identified through multivariate statistical analysis included being male and polymyxin use. CONCLUSIONS: The UK prevalence of 16S RMTase-producing Gram-negative bacteria is low, but continued surveillance is needed to monitor their spread and inform intervention strategies.

Comparison of Mycobacterial Growth Indicator Tube with Culture on RGM Selective Agar for Detection of Mycobacteria in Sputum Samples from Patients with Cystic Fibrosis.

Nontuberculous mycobacteria (NTM) are an important cause of pulmonary disease in patients with cystic fibrosis (CF). A new culture medium (RGM medium) for the isolation of rapidly growing mycobacteria from the sputum of cystic fibrosis patients has recently been reported. The aim of this study was to compare culture of sputum samples on RGM medium with culture using a standard automated liquid culture method. Sputum samples were obtained from 187 distinct patients with CF attending King's College Hospital, London, United Kingdom. Each sample was decontaminated with 3% oxalic acid and inoculated into a mycobacterial growth indicator tube (MGIT) that was monitored for 42 days using the Bactec MGIT 960 instrument. Each sample was also cultured, without decontamination, onto RGM medium, which was incubated for 10 days at 30°C. Mycobacteria were isolated from 28 patients (prevalence, 15%). Mycobacteria were detected in 24 samples (86%) using the MGIT and in 23 samples (82%) using RGM medium (P = 1.00). In this setting, RGM medium showed sensitivity equivalent to that of the MGIT for isolation of NTM from the sputum of patients with CF. RGM medium offers a simple, convenient tool that can be embedded into routine culture methods, allowing the culture of all sputum samples that are submitted from patients with CF.

Adjunctive mecA PCR for routine detection of methicillin susceptibility in clinical isolates of coagulase-negative staphylococci.

Concerns over the reliability of routine sensitivity testing in coagulase-negative staphylococci often lead to the use of potentially less-effective antibiotics as few laboratories have access to routine tests for the mecA resistance gene. Although previous studies have shown a reasonable correlation between oxacillin disc and automated sensitivity testing, changing epidemiology and methodology dictate periodic reappraisal of these methods. In the present study, we evaluated two real-time PCR assays against novel targets in the mecA gene as an adjunct to routine susceptibility testing using the Vitek II AST-P620 card. All samples were further examined for the presence of the mecC gene. Of 118 strains of coagulase-negative staphylococci tested, 81 were oxacillin resistant and 37 oxacillin susceptible by the Vitek II assay compared with 103 positive and 15 negative by mecA PCR. In-house PCR results correlated well with a previously published reference PCR, though little correlation was found between mecA PCR or Vitek II and PBP 2a latex agglutination. Incubation conditions may have affected the accuracy of the latter test. None of the strains tested were mecC PCR positive. The inclusion of dual-target PCRs in the testing algorithm was inexpensive and offered the safest strategy for determining beta-lactam susceptibility in coagulase-negative staphylococci in our laboratory.

Evaluation of the BD GeneOhm assay using the rotor-gene 6000 platform for rapid detection of methicillin-resistant Staphylococcus aureus from pooled screening swabs.

As health services move toward universal methicillin-resistant Staphylococcus aureus (MRSA) screening for hospital admissions, the most cost-effective approach is yet to be defined. In this study, one of the largest to date, we evaluated the performance of the BD GeneOhm MRSA assay on the Rotor-Gene 6000 thermal cycler, using samples taken directly from pooled MRSA screens. Results were compared with the same assay performed on the Smart-Cycler II platform and overnight broth culture. Samples yielding discrepant results were subjected to detailed analysis with an in-house PCR and patient note review. A total of 1,428 pooled MRSA screens were tested. Sensitivities and specificities of 85.3% and 95.8% for the Rotor-Gene and 81% and 95.7% for the Smart-Cycler were obtained, compared with broth enrichment. The sensitivity of the BD GeneOhm assay was increased to 100% when the results of in-house PCR and patient note review were taken into account. This study demonstrates that the Rotor-Gene 6000 thermal cycler is a reliable platform for use with the BD GeneOhm assay. It also proves that commercial PCR can be performed direct on pooled samples in selective broth, without the need for overnight incubation.

Bacteremia, acute physiology and chronic health evaluation II and modified end stage liver disease are independent predictors of mortality in critically ill nontransplanted patients with acute on chronic liver failure.

OBJECTIVES: To determine what physiological and biochemical factors predict development of bacteremia in nontransplanted patients with acute on chronic liver failure and, on diagnosis of bacteremia, what is the natural history of bacteremic patients versus control subjects (acute on chronic liver failure). INTERVENTIONS: None. DESIGN: Retrospective analysis of data collected prospectively and entered into a dedicated physiology database. SETTING: Specialist liver intensive therapy unit. PATIENTS: Critically ill non-transplanted patients with acute on chronic liver failure admitted between January 2003 and July 2005. MEASUREMENTS AND MAIN RESULTS: One hundred eighty-four patients were defined with acute on chronic liver failure; 67 (36%) had bacteremia. One hundred seventeen (64%) patients did not (acute on chronic liver failure). Fifty-eight percent of isolates were Gram-negative organisms, 36% were Gram-positives, and 6% fungemia. Median time to first bacteremia was 8 days (range, 3-12 days). On admission (univariate), bacteremic patients had significantly higher Modified End Stage Liver Disease scores (27 vs. 24, p = .037), Acute Physiology and Chronic Health Evaluation II scores (23 vs. 21, p = .049), and greater degrees of encephalopathy (Glasgow Coma Scale score 10 vs. 12, p = .001). During their liver intensive therapy unit course, bacteremic patients had significantly greater requirements for renal replacement therapy (64% vs. 49%, p = .043), mechanical ventilation (88% vs. 68%, p = .002), and a longer median liver intensive therapy unit stay (16 vs. 5 days, p < .001). Survival to hospital discharge was worse in the bacteremic group (25% vs. 56%, p < .001). Multivariate analysis (logistic regression) was performed separately modeling with Acute Physiology and Chronic Health Evaluation II and Modified End Stage Liver Disease. In the first model, Acute Physiology and Chronic Health Evaluation II (odds ratio 1.24) and bacteremia (2.24) were independent predictors of mortality. In the later model, Modified End Stage Liver Disease (odds ratio, 1.06), requirement for renal replacement therapy (3.08), Glasgow Coma Scale (0.72), and bacteremia (2.30) were significant. Both models performed similarly (Modified End Stage Liver Disease area under the receiver operating characteristic curve, 0.864; Acute Physiology and Chronic Health Evaluation II, 0.862). CONCLUSIONS: In nontransplanted patients with acute on chronic liver failure, bacteremia was associated with increased severity of illness on admission, greater requirements for organ support, and independently adversely impacted on survival. Higher Acute Physiology and Chronic Health Evaluation II and Modified End Stage Liver Disease scores were also independently predictive of mortality.

WSES guidelines for management of Clostridium difficile infection in surgical patients.

In the last two decades there have been dramatic changes in the epidemiology of Clostridium difficile infection (CDI), with increases in incidence and severity of disease in many countries worldwide. The incidence of CDI has also increased in surgical patients. Optimization of management of C difficile, has therefore become increasingly urgent. An international multidisciplinary panel of experts prepared evidenced-based World Society of Emergency Surgery (WSES) guidelines for management of CDI in surgical patients.

Bloodstream infection after elective liver transplantation is associated with increased mortality in patients with cirrhosis.

PURPOSE: This study aims to investigate what factors predict the development of postoperative bloodstream infection (BSI) in patients transplanted electively for chronic liver disease and compare outcomes in infected transplant recipients (BCLD) with noninfected patients (CLD). METHODS: A retrospective cohort study of 218 patients who had elective liver transplantation (LT) between January 2003 and July 2005 and admitted to a specialist intensive care unit (ICU) was done. RESULTS: Fifteen patients had BSI post-LT (BCLD, 29 isolates) while in the ICU, and 203 patients did not (CLD). Thirty-eight percent of isolates were gram negatives; 55%, gram positives; and 7%, fungemia. Median time to first BSI post-LT was 11 days (range, 3-16 days). On admission post-LT to the ICU, patients with BCLD had higher Acute Physiology and Chronic Health Evaluation II scores (23 vs 10, P < .001). While in the ICU, patients with BCLD had greater requirements for renal replacement therapy (73% vs 8%) and days on mechanical ventilation (17 vs 2 days) and longer median ICU stay (21 vs 3 days, P < .001 for all). One-year survival was worse in the BCLD group (40% vs 94%, P < .001). On multivariate analysis, Acute Physiology and Chronic Health Evaluation II score (odds ratio, 1.36) post-LT was independently associated with subsequent BSI. Bloodstream infection (hazards ratio, 8.7) was independently associated with mortality. CONCLUSION: Bloodstream infection post-LT was associated with increased severity of illness on admission, greater requirements for organ support, and increased mortality.

Predictors of bacteraemia and mortality in patients with acute liver failure.

PURPOSE: To determine what physiological and biochemical factors predict development of bacteraemia and mortality in patients with acute liver failure (ALF). METHODS: Retrospective analysis of 206 ALF patients admitted to a specialist liver intensive therapy unit (LITU) from January 2003 to July 2005 (data collected prospectively). RESULTS: A total of 206 patients were defined with ALF: 72 (35%) suffered bacteraemia (BAClf) and 134 (65%) did not (NBAClf). Gram positive organisms were observed in 44% of isolates, gram negatives in 52% and fungaemia in 4%. Median time to first bacteraemia was 10 (7-16) days. On admission, BAClf patients had higher SIRS scores and degrees of hepatic encephalopathy (HE). During their LITU course, BAClf patients had significantly increased requirements for renal replacement therapy (RRT), mechanical ventilation, and longer median LITU stay. Multivariate analysis (logistical regression) demonstrated significant predictors of bacteraemia on admission were HE grade >2 (Odds Ratio 1.6) and SIRS score >1 (OR 2.7). In all patients, independent predictors of mortality (logistical) were age (OR 1.41), maximum HE grade pre-intubation (1.76), Lactate (1.14) and Acute Physiology and Chronic Health Evaluation II score (APACHEII) (1.09), but not bacteraemia. Transplantation was protective (OR 0.20). CONCLUSION: In this study, severity of hepatic encephalopathy and SIRS score >1 were predictive of bacteraemia. APACHEII was independently predictive of mortality in all ALF patients but not bacteraemia.