Comparison of direct and indirect susceptibility test methods for detection of bacteraemic methicillin-resistant Staphylococcus aureus

MMed (Clinical Microbiology), Faculty of Health Sciences, University of the Witwatersrand, 2009Introduction: The clinical laboratory is required to rapidly identify Staphylococcus aureus as a cause of bacteraemia, and in particular, to detect methicillin resistance amongst bacteraemic isolates, to facilitate prompt initiation of appropriate therapy which may directly impact on patient survival, and to allow for implementation of appropriate infection control measures. Hence, the laboratory needs to choose tests to detect methicillin-resistant S. aureus (MRSA) bacteraemia which are rapid, accurate, simple, cost-effective and appropriate for the setting. Primary study objective: To determine the accuracy of four phenotypic susceptibility tests to directly detect MRSA from blood culture specimens (BC) compared with detection of the mecA gene by the polymerase chain reaction (PCR) from S. aureus cultured from the same BC. Materials and Methods: BCs were selected from patients with incident, S. aureus bacteraemic episodes at two hospitals, during January and February 2006. S. aureus was identified by standard phenotypic tests, including the presence of a deoxyribonuclease (DNAse). Direct susceptibility tests (DST) were performed (oxacillin (1μg) and cefoxitin (30μg) disk diffusion (DD), oxacillin Etest® (AB bioMérieux) and CHROMagar®-MRSA (CHROMagar® Microbiology)), and repeated on stored cultures. Detection of nuc and mecA genes by PCR confirmed S. aureus and methicillin resistance respectively. The sensitivity and specificity of the DST were calculated with reference to the mecA PCR result, to fulfil the primary study objective. Results: During the two-month study period, 9,400 BC were submitted to the clinical laboratories at the 2 hospitals; S. aureus was isolated from 156 specimens. Of these, 89 BC from 89 incident cases were included in the study, and 65 were subjected to all tests, including PCR. Of the 65 nuc-positive S. aureus isolates from 65 BC, all were positive with the direct DNAse test, and 25 (38%) were mecA positive. Compared to PCR, sensitivity and specificity for the direct oxacillin DD, cefoxitin DD, oxacillin Etest® and CHROMagar®- MRSA was 100% and 90%, 98% and 100%, 100% and 100%, and 96% and 42% respectively. Discussion: In this study, we found that, compared to PCR for the nuc and mecA genes, the combination of a direct DNAse test and oxacillin Etest®, facilitated accurate detection of MRSA bacteraemia. The direct oxacillin Etest® result did not appear to be influenced by a non-standardised inoculum, in contrast to the other direct tests, and provided an oxacillin minimum inhibitory concentration. The direct cefoxitin DD test produced more accurate results than the direct oxacillin DD test, was easier to read and distinguished MRSA from MSSA with zone diameters clustering into more clearly defined susceptibility categories. Although the chromogenic agar performed well when used to identify methicillin resistance amongst cultured S. aureus isolates, it was apparent that this test, read at 24 hours, could not be used reliably as a DST. Since the Etest® is more costly than the DD test; its use should be reserved for BC from patients in “high-risk” hospital areas, e.g. intensive care units. The direct cefoxitin DD could be used for all BC positive for GPCC, and could be used without a direct identification test because of its lower cost; it is further recommended that the direct cefoxitin DD test replace the direct oxacillin test

Skin and mucosal manifestations of an AIDS-related systemic mycosis

No abstract available.http://www.sajhivmed.org.zadm2022Internal MedicineOral Pathology and Oral Biolog

District and sub-district analysis of cryptococcal antigenaemia prevalence and specimen positivity in KwaZulu-Natal, South Africa

Background: Cryptococcal meningitis (CM) is a leading cause of mortality among HIV-positive South Africans. Reflex cryptococcal antigen (CrAg) testing of remnant plasma was offered as a pilot prior to implementation in October 2016 in KwaZulu-Natal province. The national reflex CrAg positivity was 5.4% compared to 7.3% for KwaZulu-Natal. Objectives: The aim of this study was to interrogate CrAg positivity by health levels to identify hotspots. Method: Data for the period October 2016 to June 2017 were analysed. Health district CrAg positivity and prevalence were calculated, with the latter using de-duplicated patient data. The district CrAg positivity and the number of CrAg-positive specimens per health facility were mapped using ArcGIS. For districts with the highest CrAg positivity, a sub-district CrAg positivity analysis was conducted. Results: The provincial CrAg positivity was 7.6%. District CrAg positivity ranged from 5.7% (Ugu) to 9.6% (Umkhanyakude) with prevalence ranging from 5.5% (Ugu) to 9.7% (Umkhanyakude). The highest CrAg positivity was reported for the Umkhanyakude (9.6%) and King Cetswayo (9.5%) districts. In these two districts, CrAg positivity of 10% was noted in the Umhlabuyalingana (10.0%), Jozini (10.2%), uMhlathuze (10.5%) and Nkandla (10.8%) subdistricts. In these subdistricts, 135 CrAg-positive samples were reported for the Ngwelezane hospital followed by 41 and 43 at the Hlabisa and Manguzi hospitals respectively. Conclusion: Cryptococcal antigen positivity was not uniformly distributed at either the district or sub-district levels, with identified facility hotspots in the Umkhanyakude and King Cetswayo districts. This study demonstrates the value of laboratory data to identify hotspots for planning programmatic interventions

Opportunistic fungal infections in persons living with advanced HIV disease in Lagos, Nigeria; a 12-year retrospective study

Introduction: Nigeria has a large estimated burden of AIDS-related mycoses. We aimed to determine the proportion of patients with AIDS-related opportunistic fungal infections (OFIs) at an urban antiretroviral treatment (ART) centre in Nigeria. Methods: A retrospective analysis of a cohort of ART-na\uefve, HIV-infected patients, assessed for ART eligibility and ART-experience at the PEPFAR outpatient clinic at Lagos University Teaching Hospital over a 12-year period (April 2004-February 2016) was conducted. Results: During this period, 7,034 patients visited the clinic: 4,797 (68.2%) were female; 6161 patients had a recorded baseline CD4 count, and the median CD4 count was 184 cells/\u3bcl (IQR, 84-328). A baseline HIV-1 viral load (VL) was recorded for 5,908 patients; the median VL was 51,194 RNA copies/ml (IQR, 2,316-283,508) and 6,179/7046(88%) had initiated ART. Some 2,456 (34.9%) had a documented opportunistic infections, of whom 1,306 (18.6%) had an opportunistic fungal infection. The total number of OFI episodes was 1,632: oral candidiasis (n=1,473, 90.3%), oesophageal candidiasis (n=118; 8%), superficial mycoses (n=23; 1.6%), Pneumocystis pneumonia (PJP) (n=13; 0.8%), and cryptococcal meningitis(CM) (n=5; 0.4%). 113 (1.6%) were known to have died in the cohort. Conclusion: Approximately 1 in 5 HIV-infected patients in this retrospective cohort, most of whom had initiated ART, were clinically diagnosed with an OFI. Improved access to simple accurate diagnostic tests for CM and PJP should be prioritised for this setting

Cryptococcal meningitis: improving access to essential antifungal medicines in resource-poor countries

Cryptococcal meningitis is the leading cause of adult meningitis in sub-Saharan Africa, and contributes up to 20% of AIDS-related mortality in low-income and middle-income countries every year. Antifungal treatment for cryptococcal meningitis relies on three old, off-patent antifungal drugs: amphotericin B deoxycholate, flucytosine, and fluconazole. Widely accepted treatment guidelines recommend amphotericin B and flucytosine as first-line induction treatment for cryptococcal meningitis. However, flucytosine is unavailable in Africa and most of Asia, and safe amphotericin B administration requires patient hospitalisation and careful laboratory monitoring to identify and treat common side-effects. Therefore, fluconazole monotherapy is widely used in low-income and middle-income countries for induction therapy, but treatment is associated with significantly increased rates of mortality. We review the antifungal drugs used to treat cryptococcal meningitis with respect to clinical effectiveness and access issues specific to low-income and middle-income countries. Each drug poses unique access challenges: amphotericin B through cost, toxic effects, and insufficiently coordinated distribution; flucytosine through cost and scarcity of registration; and fluconazole through challenges in maintenance of local stocks-eg, sustainability of donations or insufficient generic supplies. We advocate ten steps that need to be taken to improve access to safe and effective antifungal therapy for cryptococcal meningitis

Pathways to care and outcomes among hospitalised HIV-seropositive persons with cryptococcal meningitis in South Africa.

INTRODUCTION: Cryptococcus causes 15% of AIDS-related deaths and in South Africa, with its high HIV burden, is the dominant cause of adult meningitis. Cryptococcal meningitis (CM) mortality is high, partly because patients enter care with advanced HIV disease and because of failure of integrated care following CM diagnosis. We evaluated pathways to hospital care, missed opportunities for HIV testing and initiation of care. METHODS: We performed a cross-sectional study at five public-sector urban hospitals. We enrolled adults admitted with a first or recurrent episode of cryptococcal meningitis. Study nurses conducted interviews, supplemented by a prospective review of medical charts and laboratory records. RESULTS: From May to October 2015, 102 participants were enrolled; median age was 40 years (interquartile range [IQR] 33.9-46.7) and 56 (55%) were male. In the six weeks prior to admission, 2/102 participants were asymptomatic, 72/100 participants sought care at a public-sector facility, 16/100 paid for private health care. The median time from seeking care to admission was 4 days (IQR, 0-27 days). Of 94 HIV-seropositive participants, only 62 (66%) knew their status and 41/62 (66%) had ever taken antiretroviral treatment. Among 13 participants with a known previous CM episode, none were taking fluconazole maintenance therapy. In-hospital management was mostly amphotericin B; in-hospital mortality was high (28/92, 30%). Sixty-four participants were discharged, 92% (59/64) on maintenance fluconazole, 4% (3/64) not on fluconazole and 3% (2/64) unknown. Twelve weeks post-discharge, 31/64 (48%) participants were lost to follow up. By 12 weeks post discharge 7/33 (21%) had died. Interviewed patients were asked if they were still on fluconazole, 11% (2/18) were not. CONCLUSIONS: Among hospitalised participants with CM, there were many missed opportunities for HIV care and linkage to ART prior to admission. Universal reflex CrAg screening may prompt earlier diagnosis of cryptococcal meningitis but there is a wider problem of timely linkage to care for HIV-seropositive people

HIV Infection as Risk Factor for Death among Hospitalized Persons with Candidemia, South Africa, 2012-2017.

We determined the effect of HIV infection on deaths among persons >18 months of age with culture-confirmed candidemia at 29 sentinel hospitals in South Africa during 2012-2017. Of 1,040 case-patients with documented HIV status and in-hospital survival data, 426 (41%) were HIV-seropositive. The in-hospital case-fatality rate was 54% (228/426) for HIV-seropositive participants and 37% (230/614) for HIV-seronegative participants (crude odds ratio [OR] 1.92, 95% CI 1.50-2.47; p<0.001). After adjusting for relevant confounders (n = 907), mortality rates were 1.89 (95% CI 1.38-2.60) times higher among HIV-seropositive participants than HIV-seronegative participants (p<0.001). Compared with HIV-seronegative persons, the stratum-specific adjusted mortality OR was higher among HIV-seropositive persons not managed in intensive care units (OR 2.27, 95% CI 1.47-3.52; p<0.001) than among persons who were (OR 1.56, 95% CI 1.00-2.43; p = 0.05). Outcomes among HIV-seropositive persons with candidemia might be improved with intensive care

Cryptococcal Antigen Screening in Patients Initiating ART in South Africa: A Prospective Cohort Study.

BACKGROUND: Retrospective data suggest that cryptococcal antigen (CrAg) screening in patients with late-stage human immunodeficiency virus (HIV) initiating antiretroviral therapy (ART) may reduce cryptococcal disease and deaths. Prospective data are limited. METHODS: CrAg was measured using lateral flow assays (LFA) and latex agglutination (LA) tests in 645 HIV-positive, ART-naive patients with CD4 counts ≤100 cells/µL in Cape Town, South Africa. CrAg-positive patients were offered lumbar puncture (LP) and treated with antifungals. Patients were started on ART between 2 and 4 weeks and followed up for 1 year. RESULTS: A total of 4.3% (28/645) of patients were CrAg positive in serum and plasma with LFA. These included 16 also positive by urine LFA (2.5% of total screened) and 7 by serum LA (1.1% of total). In 4 of 10 LFA-positive cases agreeing to LP, the cerebrospinal fluid (CSF) CrAg LFA was positive. A positive CSF CrAg was associated with higher screening plasma/serum LFA titers.Among the 28 CrAg-positive patients, mortality was 14.3% at 10 weeks and 25% at 12 months. Only 1 CrAg-positive patient, who defaulted from care, died from cryptococcal meningitis (CM). Mortality in CrAg-negative patients was 11.5% at 1 year. Only 2 possible CM cases were identified in CrAg-negative patients. CONCLUSIONS: CrAg screening of individuals initiating ART and preemptive fluconazole treatment of CrAg-positive patients resulted in markedly fewer cases of CM compared with historic unscreened cohorts. Studies are needed to refine management of CrAg-positive patients who have high mortality that does not appear to be wholly attributable to cryptococcal disease

An Excel-based template for estimating induction-phase treatment costs for cryptococcal meningitis in high HIV-burden African countries

This repository contains a costing template for estimating induction-phase treatment costs for cryptococcal meningitis in high HIV-burden African countries. Four country-specific examples are included (and any of these examples can be used as a template for replication with new information, in other locations, etc. A brief User's Guide is included.This dataset is related to the following forthcoming article: Larson B, Shroufi A, Muthoga C et al. Induction-phase treatment costs for cryptococcal meningitis in high HIV-burden African countries: New opportunities with lower costs [V.1; awaiting peer review]. Wellcome Open Res 2021, 6:140 (https://doi.org/10.12688/wellcomeopenres.16776.1)BL: CDC Foundation NPG: CDC, CDC Foundation, Bill and Melinda Gates Foundation, NIH, UK MRC unrelated to the current work. NPG is partly supported by the National Institute of Allergy and Infectious Diseases of the National Institutes of Health (R01AI118511). JJ: National Institute for Health Research (NIHR) through a Global Health Professorship (grant RP-2017-08-ST2-012) using UK aid from the UK Government to support global health research. RR: National Institute of Allergy and Infectious Diseases (K23 AI38851) Disclaimer The content of this manuscript is solely the responsibility of the authors and does not necessarily represent the official views of the CDC, NIH, NIHR, the Department of Health and Social Care, or other funding entities