ABSTRACT
BACKGROUND: The rise of methicillin-resistant Staphylococcus aureus (MRSA) is a global health concern. Paucity of data on MRSA carriage prevalence and diagnostic methods in resource-limited settings hampers efforts to define the problem and plan an appropriate response. Additionally, high variability in cost and logistical characteristics of MRSA screening methods may impede infection control efforts. We compared the performance of locally-available chromogenic agar BD CHROMagar MRSA II and two PCR-based assays (Hain GenoQuick MRSA and Cepheid Xpert SA Complete) for the detection of asymptomatic MRSA carriage in nasal swabs. RESULTS: During 2015, we enrolled 500 patients from five hospital wards at a Ugandan regional referral hospital. We found 30% prevalence of methicillin-sensitive Staphylococcus aureus (MSSA) nasal carriage, and 5.4% MRSA nasal carriage prevalence. Compared to a composite reference standard defined as a positive test result on any one of the three assays, Hain GenoQuick MRSA demonstrated the highest sensitivity (96%) followed by direct plating on CHROMagar at (70%), with the lowest sensitivity observed with Xpert SA Complete (52%). Cepheid Xpert provided the most rapid results (< 1 h) but was the most expensive (US $45-50/test). Substantially more labor was required for the Hain GenoQuick MRSA compared to Xpert SA Complete or CHROMagar tests. CONCLUSION: MRSA nasal carriage prevalence rates were low, and high diagnostic sensitivity was achieved using Hain GenoQuick MRSA. Chromogenic media had significantly lower sensitivity, but may represent a viable local option given its lower cost compared to PCR-based assays.
Subject(s)
Colony Count, Microbial/methods , Diagnostic Tests, Routine/methods , Methicillin-Resistant Staphylococcus aureus/isolation & purification , Polymerase Chain Reaction/methods , Staphylococcal Infections/diagnosis , Adult , Carrier State/diagnosis , Carrier State/microbiology , Cross-Sectional Studies , Female , Humans , Male , Methicillin-Resistant Staphylococcus aureus/genetics , Methicillin-Resistant Staphylococcus aureus/growth & development , Nasal Cavity/microbiology , Staphylococcal Infections/microbiologyABSTRACT
OBJECTIVES: Lassa fever (LF), a priority emerging pathogen likely to cause major epidemics, is endemic in much of West Africa and is difficult to distinguish from other viral hemorrhagic fevers, including Ebola virus disease (EVD). Definitive diagnosis requires laboratory confirmation, which is not widely available in affected settings. The public health action to contain a LF outbreak and the challenges encountered in an EVD-affected setting are reported herein. METHODS: In February 2016, a rapid response team was deployed in Liberia in response to a cluster of LF cases. Active case finding, case investigation, contact tracing, laboratory testing, environmental investigation, risk communication, and community awareness raising were undertaken. RESULTS: From January to June 2016, 53 suspected LF cases were reported through the Integrated Disease Surveillance and Response system (IDSR). Fourteen cases (26%) were confirmed for LF, 14 (26%) did not have a sample tested, and 25 (47%) were classified as not a case following laboratory analysis. The case fatality rate in the confirmed cases was 29%. One case of international exportation was reported from Sweden. Difficulties were identified in timely specimen collection, packaging, and transportation (in confirmed cases, the time from sample collection to sample result ranged from 2 to 64 days) and a lack of response interventions for early cases. CONCLUSIONS: The delay in response to this outbreak could have been related to a number of challenges in this EVD-affected setting: a need to strengthen the IDSR system, develop preparedness plans, train rapid response teams, and build laboratory capacity. Prioritizing these actions will aid in the timely response to future outbreaks.
Subject(s)
Hemorrhagic Fever, Ebola/diagnosis , Lassa Fever/diagnosis , Adolescent , Adult , Child , Child, Preschool , Contact Tracing , Disease Outbreaks , Female , Hemorrhagic Fever, Ebola/epidemiology , Hemorrhagic Fevers, Viral/epidemiology , Humans , Infant , Liberia/epidemiology , Male , Middle Aged , Public Health , Sweden/epidemiology , Young AdultABSTRACT
SETTING: Although it is now widely used for tuberculosis (TB) diagnosis, Xpert(®) MTB/RIF availability remains inadequate in low-resource settings. Moreover, its accuracy in testing stored samples from non-expectorating patients has not been evaluated. OBJECTIVE: To assess the performance of Xpert in frozen samples of induced sputum (IS) and sputum from string test (ST) from non-expectorating individuals with presumed TB. DESIGN: This was a laboratory-based study of 377 ST and IS samples collected between March 2010 and March 2013 at a referral hospital in Uganda. Samples were decontaminated, centrifuged and cultured, and the resultant samples were frozen at -20°C before Xpert evaluation. RESULTS: TB was detected in ST and IS samples from 19/163 (11.7%) children and 63/201 (29.4%) adults using culture. Xpert sensitivity in frozen sediments from children was 37.5% (95%CI 8.5-75.5) in ST and 41.7% (95%CI 15.2-72.3) in IS samples, with specificities of respectively 100% (95%CI 94.9-100) and 98.6% (95%CI 92.7-100). In adults, sensitivity was respectively 50% (95%CI 31.3-68.7) and 48.5% (95%CI 30.8-66.4) in ST and IS samples, with specificities of respectively 100% (95%CI 95.5-100) and 98.6% (95%CI 92.4-100). CONCLUSION: Given these results, and particularly the high specificity, the use of Xpert on frozen ST and IS sediment samples from both children and adults is promising.
