Evaluating the sensitivity and specificity of dried blood spots for serological testing of HIV, syphilis, hepatitis B and C Elecsys assays on the Roche Cobas system.

This study was performed to validate a dried blood spot (DBS) method for the serological screening of HIV, syphilis, hepatitis B and C. It included 250 paired DBS and serum samples and 116 unpaired DBS samples from 366 unique patients from two laboratories between 8 October and 2 November 2021. As determined by original test request, these were tested using a DBS method for HIV Ag/Ab (n=216), anti-treponemal Ab (n=166), hepatitis B sAg (n=100), and hepatitis C Ab (n=100) Elecsys assays on the Roche Cobas automated platform. Using the manufacturer's (serum) cut-off for reactivity ('positivity'), the sensitivity and specificity of DBS testing compared with serum were: for HIV Ag/Ab 100% and 100%, for anti-treponemal Ab 68.3% and 100%, for hepatitis B sAg 95.9% and 100%, and for hepatitis C Ab 84.0% and 100%, respectively. Adjusting the assay cut-off using receiver operator curve analysis increased sensitivity of DBS testing for anti-treponemal Ab to 90.0%, hepatitis B sAg to 97.9% and hepatitis C Ab to 94.0% whilst maintaining specificity of 98.8%, 100% and 100%, respectively. With optimisation of assay cut-off, DBS can perform comparably with serum for serological testing for HIV, syphilis, hepatitis B and C and may be a valuable tool in increasing access to testing in New Zealand.

Risk factors differ for Gram-negative surgical site infection following hip and knee arthroplasty: an observational study from a national surveillance system.

AIM: To describe risk factors for surgical site infection (SSI) caused by aerobic Gram-negative organisms after hip and knee arthroplasty. METHOD: Publicly funded hip and knee arthroplasties (performed between 1 July 2013 and 31 December 2017) that developed SSIs were compared to those that did not. SSIs were grouped by causative organism: Gram-negative (Pseudomonas spp. or enteric Gram-negative bacilli) or staphylococcal (pure or mixed growth of Staphylococcus spp.). Independent risk factors in each group were identified. RESULTS: 24,842 (54%) hip and 20,993 (46%) knee arthroplasties were performed. There were 497 (1.1%) SSIs. Staphylococci were responsible for 233 SSIs (47%) and Gram-negatives were responsible for 73 (15%). Age, sex, body mass index ≥35kg/m2, smoking status, socioeconomic deprivation, American Society of Anesthesiologists classification, revision surgery and prophylactic antibiotic dose were all independent predictors of all-cause SSI. On subgroup analysis, socioeconomic deprivation and Pasifika ethnicity were independent risk factors for Gram-negative SSI, but not staphylococcal SSI. DISCUSSION: In this study, socioeconomic deprivation and ethnicity were independent and novel risk factors for Gram-negative SSI following arthroplasty. Some of the SSI risk factors can be modified before arthroplasty (e.g., appropriate timing of prophylactic antibiotics, smoking cessation, weight loss). Non-modifiable risk factors can help identify high-risk procedures where additional pre- and post-operative interventions may be warranted.

Evaluation of ssrA-targeted real time PCR for the detection of Bartonella species in human clinical samples and reflex sequencing for species-level identification.

The genus Bartonella includes species capable of causing disease in animals and humans. Due to its fastidious nature, direct detection of Bartonella causing human infection relies largely on molecular microbiological methods. Thus, it is imperative that diagnostic assays in use have the ability to detect a range of Bartonella species associated with human disease. In this study, we compared the performance of a real time polymerase chain reaction (PCR) assay targeting the ssrA gene to conventional rpoB-targeted PCR and sequencing for detection and differentiation of Bartonella species in human clinical samples. The real time ssrA PCR performed better for non-Bartonella henselae species, detecting B. clarridgeiae and B. quintana DNA in heart valve specimens that were not detected by rpoB PCR, and improved the sensitivity of B. henselae detection in blood specimens. Our findings suggest the real time ssrA PCR assay is suitable for detection and identification of Bartonella species in human clinical specimens.

Age-related differences in SARS-CoV-2 testing in the Northern Region of New Zealand.

AIM: There is concern the low incidence of coronavirus disease 2019 (COVID-19) in children reflects under-testing in this population. This study sought to describe the age-distribution of SARS-CoV-2 testing in the Northern Region of New Zealand. METHODS: A retrospective single-centre review of all SARS-CoV-2 tests performed at LabPLUS, Auckland City Hospital, between 12 February and 18 April 2020. RESULTS: A total of 22,333 tests were performed, with 313 (1.40%) positive results. The age-adjusted SARS-CoV-2 testing rate was three times higher in adults than in children. The overall proportion of positive tests was lower in children (0.86%) than adults (1.45%). However, within the paediatric population the proportion of tests positive differed significantly between those <10 years old (0.08%) and those 10-14 years old (2.6%). CONCLUSION: The lower proportion of tests positive in children <10 years of age suggests they are appropriately tested relative to their rates of disease. A large high school-associated cluster makes the higher proportion of tests positive in children 10-14 years old difficult to interpret. Older children may have a higher risk of infection and increasing testing in intermediate and high school aged children may be indicated.

Helicobacter cinaedi bacteremia in a returning traveler.

Of the non-Helicobacter pylori Helicobacter (NHPH) species, Helicobacter cinaedi is an emerging cause of infection in humans. Here we report a novel clinical presentation of H. cinaedi infection: a case of fever in a returning traveler. A 31 year old previously fit and well male presented with onset of fever 24 h after returning from travel in Singapore and Indonesia. Associated symptoms consisted of sore throat, mild shortness of breath, generalized myalgia and arthralgia, headache, and four episodes of loose stools. The patient recovered spontaneously without treatment and was discharged. After 4 days of incubation, blood cultures grew H. cinaedi. H. cinaedi is a slow-growing fastidious organism poorly detected by some commonly used automated blood culture systems, and difficult to identify using commercial or traditional biochemical identification systems. This case illustrates the importance of H. cinaedi as an emerging pathogen in immunocompetent patients, with a wide variety of possible clinical presentations. The challenges in the microbiological diagnosis of H. cinaedi infections lead us to speculate that H. cinaedi is an underdiagnosed cause of febrile illness, both in returning travelers and in other clinical settings.

Aerococcus urinae Aortitis: A Case Report.

BACKGROUND: Aerococcus urinae is a Gram-positive coccus that is increasingly recognized as a urinary pathogen since the introduction of mass spectrometry for identification of bacteria. We report a case of abdominal aortitis (with aneurysm) caused by A urinae in a male with recurrent urinary tract infections and recently treated A urinae bacteremia. A 63-year-old gentleman with a history of A urinae urosepsis 7 weeks prior, presented to the Emergency Department with thoracolumbar back pain radiating bilaterally into the groin. Radiological and surgical findings were consistent with infective infrarenal aortitis with aneurysm. METHODS: The patient successfully underwent open surgical debridement and reconstruction of the infrarenal aorta with autologous vein graft. RESULTS: Aerococcus urinae was isolated from excised tissue. The patient completed a 4-week course of intravenous antimicrobial therapy. CONCLUSIONS: Aurinae is a urinary pathogen with the ability to cause severe invasive disease including endovascular infections.

Child Mortality after Discharge from a Health Facility following Suspected Pneumonia, Meningitis or Septicaemia in Rural Gambia: A Cohort Study.

OBJECTIVE: To measure mortality and its risk factors among children discharged from a health centre in rural Gambia. METHODS: We conducted a cohort study between 12 May 2008 and 11 May 2012. Children aged 2-59 months, admitted with suspected pneumonia, sepsis, or meningitis after presenting to primary and secondary care facilities, were followed for 180 days after discharge. We developed models associating post-discharge mortality with clinical syndrome on admission and clinical risk factors. FINDINGS: One hundred and five of 3755 (2.8%) children died, 80% within 3 months of discharge. Among children aged 2-11 and 12-59 months, there were 30 and 29 deaths per 1000 children per 180 days respectively, compared to 11 and 5 respectively in the resident population. Children with suspected pneumonia unaccompanied by clinically severe malnutrition (CSM) had the lowest risk of post-discharge mortality. Mortality increased in children with suspected meningitis or septicaemia without CSM (hazard ratio [HR] 2.6 and 2.2 respectively). The risk of mortality greatly increased with CSM on admission: CSM with suspected pneumonia (HR 8.1; 95% confidence interval (CI) 4.4 to 15), suspected sepsis (HR 18.4; 95% CI 11.3 to 30), or suspected meningitis (HR 13.7; 95% CI 4.2 to 45). Independent associations with mortality were: mid-upper arm circumference (MUAC) of 11.5-13.0 cm compared to >13.0 cm (HR 7.2; 95% CI 3.0 to 17.0), MUAC 10.5-11.4 cm (HR 24; 95% CI 9.4 to 62), and MUAC <10.5 cm (HR 44; 95% CI 18 to 108), neck stiffness (HR 10.4; 95% CI 3.1 to 34.8), non-medical discharge (HR 4.7; 95% CI 2.0 to 10.9), dry season discharge (HR 2.0; 95% CI 1.2 to 3.3), while greater haemoglobin (HR 0.82; 0.73 to 0.91), axillary temperature (HR 0.71; 95% CI 0.58 to 0.87), and oxygen saturation (HR 0.96; 95% CI 0.93 to 0.99) were associated with reduced mortality. CONCLUSION: Gambian children experience increased mortality after discharge from primary and secondary care. Interventions should target both moderately and severely malnourished children.