INFECTION CONTROL IN HSCT: USE OF HEPA-FILTER

BY

IYOHA OSARETIN

DEPARTMENT OF MEDICAL MICROBIOLOGYUNIVERSITY OF BENIN TEACHING HOSPITAL

BENIN CITY

HAEMOPOEITIC STEM CELL TRANSPLANTATION (HSCT)• HSCT - infusion of hematopoietic stem cells from a donor • into a patient ( recipient)• who has received chemotherapy • which is usually marrow ablative.

• It has been used increasingly to treat: neoplastic diseases, hematologic disorders, immunodeficiency syndromes, congenital enzyme deficiencies autoimmune disorders.

Classification based on the source of the transplanted haemopoeitic progenitor cells

• allogeneic or syngeneic• autologous.

PHASE I<30 daysneutropeniabreeched barrier Candida spp, Aspergillus reactivated Herpes simplex virus

PHASE II<100 daysCMIGVHD/Tx Herpes simplex cause pneumonia, hepatitis and colitis

with potential opportunistic super infection.Pneumocystis jiroveci and Aspergillus spp.

PHASE IIICMI Humoral immunity RESCMV, Varicella zoster, EBV encapsulated bacteria

Infections

Fig.1: Bacterial infection in late post HSCT

Level of CD4+/mm3 and common pathogens

• 400

• 200

• 100

• 50

M. Tuberculosis

Varicella-zoster virus/Herpes-simplex virus

P. jiroveciCandida spp.

Cryptococcus spp.Cryptosporidium spp.

Toxoplasma spp.Cytomegalovirus M. avium

intracellulare

Bowden et al., 1995

Other organisms that can reactivate

Intracellular Biofilms Spores

M. tuberculosis CoNS Clostridium spp.

Herpes Candida spp

P. jiroveci Pseudomonas spp.

Toxoplasma spp. Others

CDC, 2000

SOURCES OF INFECTION IN HSCTHost factors (endogenous).

Reactivation of viruses (HSV, VZV, CMV)Barrier disruption causing massive disease(mucositis, IV

catheters)Colonization with resistant flora (G-ve bacteria, Vancomycin-

resistant Enterococcus (VRE), yeast)Reactivation of parasites (Toxoplasma, Strongyloides)

Environmental factors (exogenous).Importance of positive pressure ventilation (Aspergillus spores)Opportunistic pathogens (Legionella, Pneumocystis jiroveci,

Listeria

Organ transplant (blood production)viral (CMV, HBV, HCV, HIV, HHV-6, HHV-7,

Parvovirus, HTLV-)Bacterial (organ contamination, TB)Unknown (varrian Creutzfeldt – Jakob disease

(vCJD), pig retroviruses)

MANAGEMENTPrevention is preferable to treating infection in

HSCT.Regular Hand Wash by attendantGut decontaminationEarly Treatment of infection

PRE-TRANSPLANTATION SCREENINGPre-transplantation screening of the donor, recipient and / or blood

products Recipient Screening.

Ongoing or active infectionEcological testing for HBV, HCV, HIV, HSV, VZV, EBV, CMV, T. pallidum,

T. gondiiIn endemic areas, T. Cruzi, Histoplasma, Strongyloides

Donor Screening.Serological testing for HBV, HCV, HIV, T. pallidum, T. gondiiCulture of cadaveric organs, perfusates, transplant mediumClinical and epidermiological history, Tuberculin testing and fungal

serology.Screening for malaria, T. Cruzi, etc.

Blood products. Screening for HBV, HCV, HIV, T. pallidum. Leukocyte depleted blood reduces the risk of CMV

POST-TRANSPLANTATION SURVEILLANCETo guide pre-emptive therapy and monitor response

to treatment.CMV disease by PCRCandida or infection by antigen tests.Surveillance cultures for multi-drug resistant

pathogens

PREVENTION OF INFECTIONRoutine immunization e.g. pneumococcal, influenzaProphylactic antimicrobials first few months following

transplantation, e.g. Co-trimoxazole, antivirals (acroclovir, Volaciclovir, ganciclovir or

valganciclovir), antifungal (nystatin, fluconazole, or triconazole).

Protocols differ between different transplant centres.

HEPA- filter: • Highly efficient particle air filter• Developed during word war 11• Eliminates foreign particles• Filters > 0.3 microns 99.97%• Use in labs, kitchen, surgical facilities, ICU, etc.

AIR FLOW USING MOTOR/FANNOISELESS BUT ADJUSTABLEPURIFIER INCLUDING BACTERIA AND VIRUSES IF UV IS INC.FILTER REPLACEMENT-YEARLY

GENERATES NEGATIVE IONS THAT ATTRACTS PARTICLESBECOMES TOO HEAVY AND FALLS TO THE GROUND

USES PHOTOCATALYTIC OXIDATION TECHNOLOGYPROVEN EFFECTIVE AGAINST MRSA, OTHER BACTERIA, MOLDS ETC.

CONCLUSIONThe immunocompromised host - severe life threatening

infections.HSCT- immunocompromised stateThe outcome in these patients can be improved by;

prevention, including use of HEPA filter,prompt and extensive investigations ,aggressive treatment.

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