Blood Culture (Bacterial, Mycobacterial & Fungal)

1. Blood Culture (Bacterial, Mycobacterial & Fungal) Afia Zafar Aga Khan University, Pakistan

2. Plan • Impact of bacterial, mycobacterial and fungal infections in HIV/AIDS patients • Challenges in laboratory diagnosis • Recommendations

3. Bacterial Blood Stream Infections (BSIs) • Remains an important cause of illness in community & hospitals • ICU admissions due to bacterial sepsis are higher, than Pneumocystis infections (33%) Rosenberg 2001, Chiang 2011 • Frequency of BSI Lancet ID 2010

4. Community-Acquired Bacterial Bloodstream Infections in HIV-Infected Patients: A Systematic Review Michaëla et al, CID. 2014

5. Bacterial Pathogens in HIV infected Patients Community-Acquired Bacterial Bloodstream Infections in HIV-Infected Patients: A Systematic Review Michaëla et al, CID. 2014

6. The speed and accuracy of preliminary blood culture report impacts patient management & outcomes • Continuous blood culture monitoring system • Immediate reporting of Gram’s stain from positive bottles • Urgent intervention for empirical antimicrobial therapy • DST & ID testing from broth (appropriate therapy)

7. Decreased Mortality Associated With Prompt Gram Staining of Blood Cultures. Barenfanger et al Am J Clin Pathol 2008;130:870-876 871

9. Summary so far Incidence and mortality due to bacterial BSIs are higher in HIV positive patients Outcome significantly improves with continuous blood culture monitoring system based diagnosis and using molecular methods to enhance ID & AMR/resistant genes

10. Mycobacterium Tuberculosis Infections • Leading cause of death among HIV infected patientshttp://www.who.int/mediacentre/factsheets/fs104/en/index.html • 10% of new MTB among HIV patients (2011) • 50% die within a month of admission

11. 2013

12. Challenges: MTBinfection Delayed or missed diagnosis (atypical presentation) • Blood culture; not sensitive • Turnaround time; 3 weeks • High cost • ID & sensitivity: require sophisticated BSL3 lab (expensive to establish and maintain)

13. Non Tuberculous Mycobacterium (NTM)Mycobacterium avium complex (MAC) • Disseminated opportunistic infections are common • Challenges in lab diagnosis • Current diagnostic modalities are not robust • Automatic culture system: positive 7-10 days • Low positivity rate

14. Fungal Infections • Major contributors to opportunistic infections • Systemic infections are mainly with • Pneumocystis jirovecii • Cryptococcus neoformans (cryptococcosis) • Histoplasma capsulatum (histoplasmosis) • Talaromycesmarneffei (talaromycosis) • Candida albicans and other species cause nosocomial invasive diseases Lancet Infect Dis 2017

15. Histoplasmosis *21/21 +ve blood culture JID 2007 *50% +ve blood culture, JCM 2017 Talaromycosis *75% +ve blood culture in HIV patients, 90% in non HIV, microbial Pathogenesis 2017 Immunol. 2017 Lancet 2017

16. Fungal blood culture: Diagnostic Challenges • Blood & tissue cultures are slow (2-6 weeks) • Biosafety level 3 lab requirement

17. Systemic Candidiasis Kaur et al. Canadian Journal of Infectious Diseases and Medical Microbiology 2016

18. Recommendations Continuous blood culture monitoring system have an impact on patient outcome • Therefore, in a febrile HIV positive patient, blood culture should be considered for EDL • To make this service more efficient, it is desirable to add a subsidized molecular tests for ID & AST • Cost per blood culture varies (Pakistan 15$, UK100$) • Machines are expansive but available on placement basis, can be kept in central lab & bottles transported to center from small hospitals and clinics

19. Recommendations: MTB, MAC, Fungi Current, blood culture systems for MTB, MAC and fungi are not robust, expansive, technically demanding: therefore, not suitable for EDL

20. Summary • In LMIC standardized lab services have limitations • To improve the outcome, low cost, point of care tests are needed • Industry needs to develop tests (may not be dependent on electricity) and consider subsidized rates for the needy ones