SARS-CoV-2 Vaccine Immunogenicity in Patients with Gastrointestinal Cancer Receiving Systemic Anti-Cancer Therapy.

INTRODUCTION: Patients with gastrointestinal (GI) cancers have an increased risk of serious complications and death from SARS-CoV-2 infection. The immunogenicity of vaccines in patients with GI cancers receiving anti-cancer therapies is unclear. We conducted a prospective study to evaluate the prevalence of neutralizing antibodies in a cohort of GI cancer patients receiving chemotherapy following SARS-CoV-2 vaccination. MATERIALS AND METHODS: Between September 2020 and April 2021, patients with cancer undergoing chemotherapy were enrolled. At baseline (day 0), days 28, 56, and 84, we assessed serum antibodies to SARS-CoV-2 spike (anti-S) and anti-nucleocapsid (anti-NP) and concomitantly assessed virus neutralization using a pseudovirus neutralization assay. Patients received either the Pfizer/BioNTech BNT162b2, or the Oxford/AstraZeneca ChAdOx1 vaccine. RESULTS: All 152 patients enrolled had a prior diagnosis of cancer; colorectal (n = 80, 52.6%), oesophagogastric (n = 38, 25.0%), and hepato pancreatic biliary (n = 22, 12.5%). Nearly all were receiving systemic anti-cancer therapy (99.3%). Of the 51 patients who did not receive a vaccination prior to, or during the study, 5 patients had detectable anti-NP antibodies. Ninety-nine patients received at least one dose of vaccine prior to, or during the study. Within 19 days following the first dose of vaccine, 30.0% had anti-S detected in serum which increased to 70.2% at days 20-39. In the 19 days following a second dose, anti-S positivity was 84.2% (32/38). However, pseudovirus neutralization titers (pVNT80) decreased from days 20 to 39. CONCLUSION: Despite the immunosuppressive effects of chemotherapy, 2 doses of SARS-CoV-2 vaccines are able to elicit a protective immune response in patients' ongoing treatment for gastrointestinal cancers. Decreases in pseudoviral neutralization were observed after 20-39 days, re-affirming the current recommendation for vaccine booster doses. CLINICAL TRIAL REGISTRATION NUMBER: NCT04427280.

Sensitivity and specificity of monocyte distribution width (MDW) in detecting patients with infection and sepsis in patients on sepsis pathway in the emergency department.

PURPOSE: Monocyte distribution width (MDW) is a biomarker for the early identification of sepsis. We assessed its accuracy in patients presenting with suspected sepsis in the emergency department (ED). METHODS: This was a single gate, single centre study in consecutive adults (≥ 18 years) admitted to the ED with suspected sepsis and clinical history compatible with infection, between 01 January and 31 December 2020 (n = 2570). RESULTS: The overall median MDW was 22.0 (IQR 19.3, 25.6). Using Sepsis-3 (qSOFA) to define sepsis, the Area Under Curve (AUC) for a receiver operator characteristic (ROC) relationship was 0.59 (95% CI 0.56, 0.61). Discrimination was similar using other clinical scores, and to that of C-reactive protein. At an MDW cutoff of 20.0, sensitivity was 0.76 (95% CI 0.73, 0.80) and specificity 0.35 (95% CI 0.33, 0.37) for Sepsis-3. MDW showed better performance to discriminate infection, with AUC 0.72 (95% CI 0.69, 0.75). At MDW 20.0, sensitivity for infection was 0.72 (95% CI 0.70, 0.74) and specificity 0.64 (95% CI 0.59, 0.70). A sensitivity analysis excluding coronavirus disease (COVID-19) admissions (n = 552) had no impact on the AUC. MDW distribution at admission was similar for bacteraemia and COVID-19. CONCLUSIONS: In this population of ED admissions with a strong clinical suspicion of sepsis, MDW had a performance to identify sepsis comparable to that of other commonly used biomarkers. In this setting, MDW could be a useful additional marker of infection.

The impact of immunosuppressive therapy on secondary infections and antimicrobial use in COVID-19 inpatients: a retrospective cohort study.

BACKGROUND: Immunosuppressive therapies have become a cornerstone of the management of severe COVID-19. The impact of these therapies on secondary infections and antimicrobial prescribing remains unclear. We sought to assess antimicrobial use and the incidence of bacterial and fungal infections in patients with severe COVID-19, and to explore their associations with receipt of immunosuppressive therapies. METHODS: Our retrospective cohort study included 715 hospitalised, adult patients with severe COVID-19 admitted to St George's Hospital, London, UK, during the first UK pandemic wave (1st March-10th June 2020). Co-infections (occurring within 48 h of admission) and secondary infections (≥ 48 h) were defined as a positive microbiological culture with supporting clinical, radiological or laboratory data to suggest true infection. Cox regression models with time-dependent covariates were used to explore the association between immunosuppressant use and secondary infection. RESULTS: Microbiologically confirmed co-infection occurred in 4.2% (n = 30) and secondary infection in 9.3% (n = 66) of the cohort (n = 715) and were associated with in-hospital mortality (48% vs 35%, OR 1.8, 95%CI 1.1-2.7, p = 0.01). Respiratory (n = 41, 39%) and bloodstream infections (n = 38, 36%) predominated, with primarily Gram-negative pathogens. 606 (84.7%) patients received an antimicrobial, amounting to 742 days of therapy per 1000 patient-days (DOTs). In multivariable models, receipt of high-dose steroids (≥ 30 mg prednisolone or equivalent) or tocilizumab was significantly associated with increased antimicrobial consumption (+ 5.5 DOTs, 95%CI 3.4-7.7 days) but not secondary infection (HR 0.56, 95%CI 0.26-1.18). CONCLUSIONS: Bacterial and fungal infections in severe COVID-19 were uncommon. Receipt of steroids or tocilizumab was independently associated with antimicrobial consumption despite its lack of association with secondary infection. These findings should galvanise efforts to promote antimicrobial stewardship in patients with COVID-19.

Impact of rapid susceptibility testing on antimicrobial therapy and clinical outcomes in Gram-negative bloodstream infections.

BACKGROUND: Rapid antimicrobial susceptibility testing (rAST) has the potential to improve care of bloodstream infections. OBJECTIVES: The aim of this service evaluation was to assess the impact of rAST on antimicrobial therapy and clinical outcomes in patients with Gram-negative bloodstream infection. METHODS: A prospective service evaluation was conducted from March 2018 to December 2018. A rAST system (Alfred 60AST) was run Monday-Friday before midday and results were communicated to clinicians on the same day as positive blood culture, with subsequent conventional AST performed. Times to antibiotic therapy and clinical outcomes were compared between rAST and conventional AST. RESULTS: One hundred and ninety-one patients with Gram-negative bacteraemia were included (93 in the rapid group and 98 in the conventional group). Aminoglycoside combination therapy was stopped earlier in the rapid group [32 h (0-795) versus 54 h (4-216), P = 0.002]. The median time to optimal antibiotic based on AST results was significantly shorter than that in the conventional group [50 h (10-339) versus 69.5 h (20-872), P = 0.034]. In the subgroup of patients on ineffective empirical antibiotic, time to effective antibiotic was shorter in the rapid group [39.5 h (32-97) versus 57 h (49-83), P = 0.036]. No differences were found in 28 day mortality or length of stay. CONCLUSIONS: Rapid susceptibility testing resulted in faster discontinuation of aminoglycosides and a shorter time to starting effective and optimal antibiotic when compared with conventional AST results. rAST has potential clinical benefits and points to the need for larger future studies in areas of high antibiotic resistance.

Increased risk of death in COVID-19 hospital admissions during the second wave as compared to the first epidemic wave: a prospective, single-centre cohort study in London, UK.

BACKGROUND: The second coronavirus disease (COVID-19) epidemic wave in the UK progressed aggressively and was characterised by the emergence and circulation of variant of concern alpha (VOC 202012/01). The impact of this variant on in-hospital COVID-19-specific mortality has not been widely studied. We aimed to compare mortality, clinical characteristics, and management of COVID-19 patients across epidemic waves to better understand the progression of the epidemic at a hospital level and support resource planning. METHODS: We conducted an analytical, dynamic cohort study in a large hospital in South London. We included all adults (≥ 18 years) with confirmed severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) who required hospital admission to COVID-19-specific wards between January 2020 and March 2021 (n = 2701). Outcome was COVID-19-specific in-hospital mortality ascertained through Medical Certificate Cause of Death. RESULTS: In the second wave, the number of COVID-19 admissions doubled, and the crude mortality rate dropped 25% (1.66 versus 2.23 per 100 person-days in second and first wave, respectively). After accounting for age, sex, dexamethasone, oxygen requirements, symptoms at admission and Charlson Comorbidity Index, mortality hazard ratio associated with COVID-19 admissions was 1.62 (95% CI 1.26, 2.08) times higher in the second wave. CONCLUSIONS: Although crude mortality rates dropped during the second wave, the multivariable analysis suggests a higher underlying risk of death for COVID-19 admissions in the second wave. These findings are ecologically correlated with an increased circulation of SARS-CoV-2 variant of concern 202012/1 (alpha). Availability of improved management, particularly dexamethasone, was important in reducing risk of death.

Persistence of SARS-CoV-2 N-Antibody Response in Healthcare Workers, London, UK.

Prospective serosurveillance of severe acute respiratory syndrome coronavirus 2 in 1,069 healthcare workers in London, UK, demonstrated that nucleocapsid antibody titers were stable and sustained for <12 weeks in 312 seropositive participants. This finding was consistent across demographic and clinical variables and contrasts with reports of short-term antibody waning.

Rapid versus standard antimicrobial susceptibility testing to guide treatment of bloodstream infection.

BACKGROUND: Rapid antimicrobial susceptibility tests are expected to reduce the time to clinically important results of a blood culture. This might enable clinicians to better target therapy to a person's needs, and thereby, improve health outcomes (mortality, length of hospital stay), and reduce unnecessary prescribing of broad-spectrum antibiotics; thereby reducing antimicrobial resistance rates. OBJECTIVES: To assess the effects of rapid susceptibility testing versus standard susceptibility testing for bloodstream infections (BSIs). SEARCH METHODS: To identify studies with selected outcomes, we searched the Cochrane Infectious Diseases Group Specialised Register, CENTRAL, MEDLINE, LILACS, and two trials registries, between 1987 and October 2020. We used 'bloodstream infection' and 'antimicrobial susceptibility tests' as search terms. We had no language or publication status limitations. SELECTION CRITERIA: Randomized controlled trials (RCTs) comparing rapid antimicrobial susceptibility testing (with a time-to-result of ≤ 8 hours) versus conventional antimicrobial susceptibility testing in people with a BSI caused by any bacteria, as identified by a positive blood culture. DATA COLLECTION AND ANALYSIS: Two review authors independently screened references, full-text reports of potentially relevant studies, extracted data from the studies, and assessed risk of bias. Any disagreement was discussed and resolved with a third review author. For mortality, a dichotomous outcome, we extracted the number of events in each arm, and presented a risk ratio (RR) with 95% confidence interval (CI) to compare rapid susceptibility testing to conventional methods. We used Review Manager 5.4 to meta-analyse the data. For other outcomes, which are time-to-event outcomes (time-to-discharge from hospital, time-to-first appropriate antibiotic change), we conducted qualitative narrative synthesis, due to heterogeneity of outcome measures.  MAIN RESULTS: We included six trials, with 1638 participants. For rapid antimicrobial susceptibility testing compared to conventional methods, there was little or no difference in mortality between groups (RR 1.10, 95% CI 0.82 to 1.46; 6 RCTs, 1638 participants; low-certainty evidence). In subgroup analysis, for rapid genotypic or molecular antimicrobial susceptibility testing compared to conventional methods, there was little or no difference in mortality between groups (RR 1.02, 95% CI 0.69 to 1.49; 4 RCTs, 1074 participants; low-certainty evidence). For phenotypic rapid susceptibility testing compared to conventional methods, there was little or no difference in mortality between groups  (RR 1.37, 95% CI 0.80 to 2.35; 2 RCTs, 564 participants; low-certainty evidence). In qualitative analysis, rapid susceptibility testing may make little or no difference in time-to-discharge (4 RCTs, 1165 participants; low-certainty evidence). In qualitative analysis, rapid genotypic susceptibility testing compared to conventional testing may make little or no difference in time-to-appropriate antibiotic (3 RCTs, 929 participants; low-certainty evidence). In subgroup analysis, rapid phenotypic susceptibility testing compared to conventional testing may improve time-to-appropriate antibiotic (RR -17.29, CI -45.05 to 10.47; 2 RCTs, 564 participants; low-certainty evidence).  AUTHORS' CONCLUSIONS: The theoretical benefits of rapid susceptibility testing have not been demonstrated to directly improve mortality, time-to-discharge, or time-to-appropriate antibiotic in these randomized studies. Future large prospective studies should be designed to focus on the most clinically meaningful outcomes, and aim to optimize blood culture pathways.

Evaluation of a new Rapid Antimicrobial Susceptibility system for Gram-negative and Gram-positive bloodstream infections: speed and accuracy of Alfred 60AST.

BACKGROUND: Blood stream infections (BSIs) are a major cause of morbidity and mortality. The time from taking blood cultures to obtain results of antibiotic sensitivity can be up to five days which impacts patient care. The Alfred 60 AST™ can reduce laboratory time from positive culture bottle to susceptibility results from 16 to 25 h to 5-6 h, transforming patient care. To evaluate the diagnostic accuracy of a rapid antimicrobial susceptibility system, the Alfred 60 AST™, in clinical isolates from patients with BSIs and confirm time to results. 301 Gram-negative and 86 Gram-positive isolates were analysed directly from positive blood culture bottles following Gram staining. Antimicrobial susceptibility results and time-to-results obtained by rapid Alfred 60 AST system and BD Phoenix were compared . RESULTS: A total of 2196 antimicrobial susceptibility test results (AST) were performed: 1863 Gram-negative and 333 Gram-positive. AST categorical agreement (CA) for Alfred 60 AST™ was 95% (1772/1863) for Gram-negative and 89% (295/333) for Gram-positive isolates. Gram-negative CA: ampicillin 96% (290/301); ciprofloxacin 95% (283/297); ceftriaxone 96% (75/78); meropenem 97% (288/297); piperacillin-tazobactam 95% (280/295); gentamicin 94% (279/297) and amikacin 93% (277/298). The median time to susceptibility results from blood culture flagging positive was 6.3 h vs 20 h (p < 0.01) for Alfred system vs BD Phoenix™. CONCLUSION: Alfred 60 AST system greatly reduced time to antimicrobial susceptibility results in Gram-negative and Gram-positive BSIs with good performance and cost, particularly for Gram-negative bacteraemia.

Diagnosis and outcome of Clostridium difficile infection by toxin enzyme immunoassay and polymerase chain reaction in an island population.

BACKGROUND AND AIM: Clostridium difficile infection (CDI) is a potentially life-threatening cause of diarrhea. Correct laboratory diagnosis is essential to differentiate CDI from other causes of diarrhea. A positive fecal C. difficile toxin (CDT) is the best indicator of CDI, but the significance of a positive fecal nucleic acid amplification test (NAAT) remains unclear. Our aim was to elucidate the significance of CDI diagnostics in patients in Jersey. METHODS: A retrospective, 5-year study was conducted at an island district general hospital of patients who developed CDI. Patients were grouped according to CDT and NAAT status and their association with outcome (indicators of severity and 30-day case-fatality rate) compared. RESULTS: A total of 207 specimens were toxin positive, 92 NAAT positive and toxin negative, and 39 had a stool sample negative by both toxin and NAAT testing. A positive toxin stool sample was associated with both significantly higher white cell count (14.5 × 109 /L vs 11.3 × 109 /L, P = 0.003) and C-reactive protein (114.7 mg/dL vs 82.9 mg/dL, P = 0.001), but NAAT positivity was not (P = 0.269, 0.728). A positive CDT assay was a significant independent predictor of death (odds ratio [OR]: 1.89 [95% CI: 1.04-3.43], P = 0.046), but a positive NAAT in CDT negative samples was not (OR: 1.02 [95% CI: 0.34-3.12], P = 1.0). CONCLUSIONS: The findings of this study, derived from evolving clinical practice, provide greater clarity in the interpretation of CDI diagnostics. In CDT-negative disease, a positive NAAT neither predicts disease severity nor mortality. NAAT-positive and toxin-negative patients require instigation of infection control measures, but the need for specific treatment remains unclear.

Accurate detection of Neisseria gonorrhoeae ciprofloxacin susceptibility directly from genital and extragenital clinical samples: towards genotype-guided antimicrobial therapy.

INTRODUCTION: Increasing use of nucleic acid amplification tests (NAATs) as the primary means of diagnosing gonococcal infection has resulted in diminished availability of Neisseria gonorrhoeae antimicrobial susceptibility data. We conducted a prospective diagnostic assessment of a real-time PCR assay (NGSNP) enabling direct detection of gonococcal ciprofloxacin susceptibility from a range of clinical sample types. METHODS: NGSNP, designed to discriminate an SNP associated with ciprofloxacin resistance within the N. gonorrhoeae genome, was validated using a characterized panel of geographically diverse isolates (n = 90) and evaluated to predict ciprofloxacin susceptibility directly on N. gonorrhoeae-positive NAAT lysates derived from genital (n = 174) and non-genital (n = 116) samples (n = 290), from 222 culture-confirmed clinical episodes of gonococcal infection. RESULTS: NGSNP correctly genotyped all phenotypically susceptible (n = 49) and resistant (n = 41) panel isolates. Ciprofloxacin-resistant N. gonorrhoeae was responsible for infection in 29.7% (n = 66) of clinical episodes evaluated. Compared with phenotypic susceptibility testing, NGSNP demonstrated sensitivity and specificity of 95.8% (95% CI 91.5%-98.3%) and 100% (95% CI 94.7%-100%), respectively, for detecting ciprofloxacin-susceptible N. gonorrhoeae, with a positive predictive value of 100% (95% CI 97.7%-100%). Applied to urogenital (n = 164), rectal (n = 40) and pharyngeal samples alone (n = 30), positive predictive values were 100% (95% CI 96.8%-100%), 100% (95% CI 87.2%-100%) and 100% (95% CI 82.4%-100%), respectively. CONCLUSIONS: Genotypic prediction of N. gonorrhoeae ciprofloxacin susceptibility directly from clinical samples was highly accurate and, in the absence of culture, will facilitate use of tailored therapy for gonococcal infection, sparing use of current empirical treatment regimens and enhancing acquisition of susceptibility data for surveillance.

High-Resolution Analysis by Whole-Genome Sequencing of an International Lineage (Sequence Type 111) of Pseudomonas aeruginosa Associated with Metallo-Carbapenemases in the United Kingdom.

Whole-genome sequencing (WGS) was carried out on 87 isolates of sequence type 111 (ST-111) of Pseudomonas aeruginosa collected between 2005 and 2014 from 65 patients and 12 environmental isolates from 24 hospital laboratories across the United Kingdom on an Illumina HiSeq instrument. Most isolates (73) carried VIM-2, but others carried IMP-1 or IMP-13 (5) or NDM-1 (1); one isolate had VIM-2 and IMP-18, and 7 carried no metallo-beta-lactamase (MBL) gene. Single nucleotide polymorphism analysis divided the isolates into distinct clusters; the NDM-1 isolate was an outlier, and the IMP isolates and 6/7 MBL-negative isolates clustered separately from the main set of 73 VIM-2 isolates. Within the VIM-2 set, there were at least 3 distinct clusters, including a tightly clustered set of isolates from 3 hospital laboratories consistent with an outbreak from a single introduction that was quickly brought under control and a much broader set dominated by isolates from a long-running outbreak in a London hospital likely seeded from an environmental source, requiring different control measures; isolates from 7 other hospital laboratories in London and southeast England were also included. Bayesian evolutionary analysis indicated that all the isolates shared a common ancestor dating back ∼50 years (1960s), with the main VIM-2 set separating approximately 20 to 30 years ago. Accessory gene profiling revealed blocks of genes associated with particular clusters, with some having high similarity (≥95%) to bacteriophage genes. WGS of widely found international lineages such as ST-111 provides the necessary resolution to inform epidemiological investigations and intervention policies.

Trends in paediatric nosocomial bacteraemia in a London tertiary hospital.

AIM: To describe the incidence and microbiological characteristics of nosocomial bloodstream infections in childhood over a 9-year period at a South London tertiary hospital. METHODS: Analysis of prospective data collected for clinically significant nosocomial bloodstream infections in children aged <16 years during 2001-2009. RESULTS: During the study period, although the absolute number of nosocomial bloodstream infections were similar for the neonatal unit (n = 254) and paediatric wards (n = 224), rates were 11.6-fold (95% CI, 9.8-13.9) higher for the former (5.8 vs. 0.50/100 discharges, respectively). Analysis of trends revealed a significant reduction in rates for both the neonatal unit (7.8-2.5 episodes/100 discharges; p < 0.001) and paediatric wards (1.2-0.4 episodes/100 discharges; p < 0.001), mainly due a decline in catheter-associated staphylococcal bacteraemia, which accounted for 115 (45%) and 164 (73%) episodes in the paediatric wards and neonatal units, respectively. Gram-positive cocci were the most frequent pathogens recovered, accounting for 200 (79%) and 185 (83%) cases in the neonatal unit and paediatric wards, respectively. Overall, antimicrobial resistance rates were low compared with other industrialized countries. CONCLUSION: Nosocomial bloodstream infections rates declined significantly in our hospital over the past decade, likely driven by local introduction of national infection-control bundles particularly focussing on insertion and maintenance of intravascular catheters.

Real-World Budget Impact of Fidaxomicin versus Vancomycin or Metronidazole for In-Hospital Treatment of Clostridioides difficile Infection

Fidaxomicin, a macrocyclic antibiotic, selectively kills Clostridioides difficile and reduces C. difficile infection (CDI) recurrence compared with vancomycin, but some studies and guidelines report fidaxomicin as being less cost-effective. The aim of this study was to compare the cost-effectiveness and budget impact of fidaxomicin versus vancomycin or metronidazole for treating CDI in a real-world UK setting. Data were retrospectively collected from medical records of 86 patients with CDI treated with vancomycin or metronidazole at a single UK hospital between April 2011 and March 2012, and prospectively from 62 patients with CDI treated with fidaxomicin between August 2012 and July 2013. CDI cases were matched by age, financial year, and healthcare resource use to control cases. CDI recurrence rates were lower with fidaxomicin (6.5%) than vancomycin/metronidazole (19.8%). An estimated 12 additional recurrent CDIs were prevented with fidaxomicin treatment. Patients with CDI had significantly higher healthcare costs than those without CDI, with a mean excess spend of GBP 10,748 and GBP 17,451 per patient in the fidaxomicin (p = 0.015) and vancomycin/metronidazole cohorts (p < 0.001), respectively. A second CDI was associated with mean excess costs of GBP 8373 and GBP 20,249 per patient in the fidaxomicin and vancomycin/metronidazole cohorts, respectively. Despite higher fidaxomicin drug costs, overall cost savings were estimated at GBP 140,292 (GBP 2125 per CDI). In this real-world study, first-line CDI treatment with fidaxomicin reduced healthcare costs versus vancomycin/metronidazole, consistent with previous studies.

Clinical, microbiological characteristics and predictors of mortality in patients with carbapenemase-producing Enterobacterales bloodstream infections: a multicentre study.

Objectives: To investigate the clinical, microbiological characteristics and outcomes of patients with bloodstream infections (BSI) due to carbapenemase-producing Enterobacterales (CPE). Methods: A multicentre retrospective observational study of patients with BSIs due to CPE admitted to six UK hospitals was conducted between 2011 and 2021. Multivariate analysis was used to identify factors predicting 30-day case fatality rate (CFR). Results: There were 84 episodes of CPE-BSIs, 37 (44%) due to OXA-48, 35 (42%) to metallo-betalactamases (MBL) and 12 (14%) to KPC. 63% of patients were male with a median age of 64 years. Common organisms included Klebsiella spp. (61%), Escherichia coli (20%) and Enterobacter spp. (13%). Urinary devices were more often involved in OXA-48 BSIs (12/37; 32%) compared to infections caused by MBL and KPC (4/35; 11% and 1/12; 8%; P = 0.046). In contrast, central venous catheters were more frequently present in KPC-BSIs (10/12; 92%) compared with OXA-48 and MBL (11/37; 30% and 20/35; 57%; P = 0.002). Effective definitive antimicrobials were received by 72/84 (86%) patients, comprising monotherapy (32/72; 44%) or combination therapy (40/72; 56%). 30-day case fatality rate (CFR) was 38%. Sepsis or septic shock was associated with death [OR 3.81 (CI 1.19-12.14), P = 0.024]. Conclusion: Strategies targeting high-risk patients and adherence to infection prevention bundles for urinary devices and central venous catheters can reduce OXA-48 and KPC-BSIs. Early recognition and management of severe sepsis, prompt initiation of appropriate antimicrobial therapy and development of novel antimicrobials are crucial to mitigate the high CFR associated with CPE-BSIs.

Shift in dominant hospital-associated methicillin-resistant Staphylococcus aureus (HA-MRSA) clones over time.

OBJECTIVES: The majority of HA-MRSA infections are caused by endogenous infection and by only a small number of clones. The reasons for the success of some clones over others are unknown. METHODS: We investigated the evolution of an MRSA population from a large, acute-care teaching hospital in London, UK over a 10 year period. MRSA incidence and antibiotic prescribing were correlated with changes in resistance genes and prevalence of clonal groups. RESULTS: Three clones caused the majority of infections, CC30 SCCmecII (EMRSA-16), CC22 SCCmecIV (EMRSA-15) and ST239 SCCmecIII. Clones that were multidrug resistant were selected for, and CC22 became dominant once it acquired a wide range of extra resistance genes. CC22 MRSA was also the fittest clone in an independent growth assay and a competition assay, and had a greater ability to survive desiccation. No individual isolate was fully drug resistant, and there was evidence of substantial horizontal gene transfer (HGT) as well as resistance gene loss within the clonal groups. The exception was fluoroquinolone resistance, which was rarely lost by any of the dominant hospital clones, suggesting that this resistance contributes to selection and survival of HA-MRSA. In support of this, a decrease in hospital-wide ciprofloxacin (a fluoroquinolone) prescribing was strongly associated with an overall decrease in MRSA infection. CONCLUSION: Our data suggest successful HA-MRSA clones such as CC22 SCCmecIV are resistant to fluoroquinolones as well as fitter and able to acquire, but not necessarily accumulate, resistance to a wide range of additional antibiotics.

Increased monocyte distribution width in COVID-19 and sepsis arises from a complex interplay of altered monocyte cellular size and subset frequency.

INTRODUCTION: Monocyte distribution width (MDW), a parameter generated alongside full blood counts (FBC) in new-generation haematology analysers, has been proposed as a diagnostic test for severe infection/sepsis. It represents the standard deviation (SD) of the monocyte mean volume (MMV). METHODS: This study aimed to compare monocyte volumetric parameters retrieved by the UniCel DxH 900 haematology analyser (MMV and MDW) against corresponding parameters from the same sample measured using flow cytometry (forward scatter [FSC] mean and SD) in combination with phenotypic characterization of monocyte subtypes. We analysed blood samples from healthy individuals (n = 11) and patients with conditions associated with elevated MDW: sepsis (n = 26) and COVID-19 (n = 15). RESULTS: Between-instrument comparisons of monocyte volume parameters (MMV vs. FSC-mean) showed relatively good levels of correlation, but comparisons across volume variability parameters (MDW vs. FSC-SD) were poor. Stratification on sample type revealed this lack of correlation only within the sepsis group. Flow cytometry analysis revealed that in healthy controls intermediate monocytes are the largest and non-classical the smallest cells. In each disease state, however, each monocyte subset undergoes different changes in volume and frequency that together determine the overall configuration of the monocyte population. Increased MDW was associated with reduced classical monocyte frequency and increased intermediate monocyte size. In COVID-19, the range of monocyte sizes (smallest to largest) reduced, whereas in sepsis it increased. CONCLUSION: Increased MDW in COVID-19 and sepsis has no single flow cytometric phenotypic correlate. It represents-within a single value-the delicate equipoise between monocyte subset frequency and size.

Prevalence of neutralising antibodies against SARS-CoV-2 in acute infection and convalescence: A systematic review and meta-analysis.

BACKGROUND: Individuals infected with SARS-CoV-2 develop neutralising antibodies. We investigated the proportion of individuals with SARS-CoV-2 neutralising antibodies after infection and how this proportion varies with selected covariates. METHODOLOGY/PRINCIPAL FINDINGS: This systematic review and meta-analysis examined the proportion of individuals with SARS-CoV-2 neutralising antibodies after infection and how these proportions vary with selected covariates. Three models using the maximum likelihood method assessed these proportions by study group, covariates and individually extracted data (protocol CRD42020208913). A total of 983 reports were identified and 27 were included. The pooled (95%CI) proportion of individuals with neutralising antibodies was 85.3% (83.5-86.9) using the titre cut off >1:20 and 83.9% (82.2-85.6), 70.2% (68.1-72.5) and 54.2% (52.0-56.5) with titres >1:40, >1:80 and >1:160, respectively. These proportions were higher among patients with severe COVID-19 (e.g., titres >1:80, 84.8% [80.0-89.2], >1:160, 74.4% [67.5-79.7]) than those with mild presentation (56.7% [49.9-62.9] and 44.1% [37.3-50.6], respectively) and lowest among asymptomatic infections (28.6% [17.9-39.2] and 10.0% [3.7-20.1], respectively). IgG and neutralising antibody levels correlated poorly. CONCLUSIONS/SIGNIFICANCE: 85% of individuals with proven SARS-CoV-2 infection had detectable neutralising antibodies. This proportion varied with disease severity, study setting, time since infection and the method used to measure antibodies.

Nitric oxide generation in children with malaria and the NOS2G-954C promoter polymorphism.

Previous epidemiological studies have demonstrated a protective association between the NOS2G-954C (NOS2(Lambaréné)) polymorphism in inducible nitric oxide synthase and severe malaria. The polymorphism is commoner in children with uncomplicated compared with severe malaria. We now show that the likely mechanism for such protection is increased flux of nitrogen from arginine to nitric oxide (NO) during episodes of malaria. Forty-seven boys with uncomplicated malaria received an infusion of (15)N-arginine to measure directly whole body in vivo NO production. The NOS2G-954C genotype previously associated with reduced risk of severe malaria in Gabon was also assessed. Evaluable data were obtained from 40 boys, of whom 6 were NOS2G-954C heterozygotes. Heterozygotes had higher urinary (15)N nitrate enrichments, 2.3 ± 0.6 vs. 1.4 ± 0.5 atoms percent excess (P = 0.001) and higher ratios of (15)N between urine nitrate and plasma arginine (87 ± 11 vs. 57 ± 18%, P = 0.001) consistent with accelerated NO production. We also derived total NO production rates, combining data with total urine production rate and nitrate concentration; these showed no difference by genotype (0.62 ± 0.36, n = 6 vs. 0.83 ± 0.50 µmol/kg·h, n = 16; P = 0.36), but data were confounded by very high variability in measurements of urine output and nitrate concentrations. This study supports the idea that NOS2 genotype protects against severe malaria by increasing NO production during episodes of uncomplicated malaria.

Positive predictive value of the Becton Dickinson VIPER system and the ProbeTec GC Q x assay, in extracted mode, for detection of Neisseria gonorrhoeae.

OBJECTIVES: Performance of the new Becton Dickinson ProbeTec GC Q(x) assay on the BD VIPER platform was evaluated to ascertain whether confirmatory testing is required in our clinical setting. METHODS: Positive predictive value (PPV) was determined by comparison with culture and a confirmatory nucleic acid amplification test (NAAT)-based Neisseria gonorrhoeae assay from genital and extragenital samples (rectal and pharyngeal) collected from a genitourinary medicine (GUM) clinic. RESULTS: Among 14,223 clinical genital samples, 149 (1.0%) specimens were positive using the ProbeTec GC Q(x) assay, automated on the VIPER platform; 141 of these were confirmed by either culture or a real-time PCR targeting two gonococcal-specific targets (PPV 94.6%; 95% CI 90% to 98%). Among 840 pharyngeal samples, 26 (3.1%) were positive by the ProbeTec GC Q(x) assay; 13 were confirmed (PPV 50%; 95% CI 30% to 70%). Among 593 rectal samples, 17 tested positive by the ProbeTec GC Q(x) assay; all were confirmed (PPV 100%; 95% CI 80% to 100%). CONCLUSIONS: The lower 95% CI of the PPV for the ProbeTec GC Q(x) assay for genital specimens was >90% in this GUM clinic population, and therefore confirmatory testing for genital specimens is not required. Confirmatory testing of pharyngeal and rectal samples should continue in line with national guidelines.