1. Blood Culture (Bacterial, Mycobacterial & Fungal)
The speed and accuracy of preliminary blood culture reports impacts patient management and outcomes
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. Turn around time of Gram stain from positive blood culture bottle to caregivers ( n= 99 matched group)
Crude mortality
less than 0.1 hour
10.1%
3.3 hours
19.2%
Decreased Mortality Associated With Prompt Gram Staining of Blood Cultures. Barenfanger et al
Am J Clin Pathol 2008;130:

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 patients
10% of new MTB among HIV patients (2011)
50% die within a month of admission
Although cases have been declined 2000 to 2016

11. 1 in 4 adult HIV+ve hospitalized patient in sepsis Shevin TJ, 2013 PLOS

12. Challenges: MTB infection
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)
The prevalence of mycobacteremia among HIV-infected hospitalized febrile patients ranges from 9 to 22% [12-15]. In Uganda, mycobacteremia has been reported in 23% of hospitalized HIV-infected patients with sepsis, half of whom die within a month of admission [16]. Mortality in patients with mycobacteremia often results from delayed or missed TB diagnosis. Early diagnosis and treatment therefore has the potential to reduce mycobacteremia attributable mortality [17]. However, diagnosis of mycobacteremia is often delayed due to atypical presentation, which makes clinical diagnosis more difficult [18-21]. The high cost of TB blood culture and the need for sophisticated laboratory infrastructure make the test unaffordable for routine patient care in high prevalence HIV/TB resource-limited settings [22]. In addition, TB blood culture has a minimum turnaround time of 3 weeks [23,24] which further contributes to delayed diagnosis and subsequent morbidity and mortality. Death occurs before TB blood culture results in the majority of patients [14]. Given the duration required for MTB growth in blood culture, clinical predictors of MTB bacteremia and rapid diagnostic tests may improve early diagnosis of mycobacteremia particularly in settings with increased HIV /TB co infection. Mortality in HIV- infected, smear-negative TB patients could be reduced through early identification and treatment of patients who have MTB bacteremia.

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
Disseminated MAC infection is the most common opportunistic bacterial infection in HIV patients 1,2
Annual incidence is approx. 20% after 1st they diagnosed AIDS.3
Although disseminated M. avium complex disease appears late in the course of HIV disease,1,2 it is an independent predictor of mortality, even after adjustment for the CD4 lymphocyte count.4,5 Treating M. avium complex bacteremia can lead to both clinical and bacteriologic improvement.1,2,6-8 Several retrospective studies9-12 and one prospective, nonrandomized study13 have shown increased survival with treatment.

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

15. Histoplasmosis Talaromycosis *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
Histoplasmosis: Incidence of 15.4/1000 person-years in HIV-infected patients, 39% of deaths following diagnosis in endemic areas 58% in non endemic area . Available modalities: Fungal culture of tissue
Molecular techniques: PCR, Sequencing
Serologic testing (90% in cavitary lesion, < sensi in immunosuppressed 50-80%)
Antigen detection (sensitivity 80%-95%), urine?
T marneffei: Major cause of death, (2nd after MTB, Crypt & Pneumocystis pneum
Immunocompromised residents & travelers in SEA, South China, & NE India, Vietnam 4–11% deaths in AIDS cases
Immunol. 2017
Lancet 2017

16. Fungal blood culture: Diagnostic Challenges
Blood & tissue cultures are slow (2-6 weeks)
Biosafety level 3 lab requirement
Fungal culture of tissue
Molecular techniques: PCR, Sequencing
Serologic testing (90% in cavitary lesion, < sensi in immunosuppressed 50-80%)
Antigen detection (sensitivity 80%-95%), urine?

17. Systemic Candidiasis
Kaur et al. Canadian Journal of Infectious Diseases and Medical Microbiology 2016
BSIs with Candida spp. are cause of morbidity and mortality in hospitalized patients

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