Genetic relationships between Candida albicans strains isolated from dental plaque, trachea, and bronchoalveolar lavage fluid from mechanically ventilated intensive care unit patients

Seok-Mo Heo, Robert S. Sung, Frank A. Scannapieco andElaine M. Haase

Presented by: Susana Ríos Echavarría. Carolina Severiche Mena.

Medicine- Third semesterUniversidad Pontificia Bolivariana.

INTRODUCTION

GENETIC vs PATHOLOGY

GENERAL OBJECTIVE

Determine genetic relationships between Candida albicans strains isolated from dental plaque, trachea, and bronchoalveolar lavage fluid from mechanically ventilated intensive care unit patients.

MATERIALES Y METODOS

1. POBLACION DE ESTUDIO

2. MUESTREO MICROBIANO DE LA CAVIDAD ORAL, TRÁQUEA Y PULMÓN.

MATERIALES Y METODOS

3. LISIS CELULAR EN GEL Y ADICIÓN DEL TAPÓN DE ENZIMA DE RESTRICCIÓN.

MATERIALES Y METODOS

MATERIALES Y METODOS

4. PFGE (ELECTROFORESIS EN GEL DE CAMPO PULSADO) Y BANDAS DE ANÁLISIS Y PATRONES DE INTERPRETACIÓN.

ABREVIACIONES DE LOS RESULTADOS

SG: supragingival dental plaque

TS: tracheal secretion

BL: bronchoalveolarlavage.

Pt ID: Patient identification

Source: sample site

Day: Number of days after admission to the intensive care unit that the strain was isolated.

•62 de 96 pacientes fueron colonizados:

•De 30 con BL: 20 con C.albicans en boca,16 tráquea y 2 en BL.

•22 con ventilación mecánica en UCI= 19 en boca, 17 en tráquea y 2 en pulmones

•De los 22, 12 tienen el agente en dos sitios y 2 lo tienen en mas de 2 sitios.

•1 solo paciente tuvo relación entre las tres muestras.

RESULTADOS

1. Electrophoretic karyotypes(EK) with dendogram for C.albicans isolates:

1.1 Intra-patient PFGE analysis:

• 13 de 14 son idénticos.• Paciente 89= 96% Similaridad

genética.

1.2 Inter-patient PFGE analysis:

• 1,15,21,24= patron EK y agrupados.• 41,70 y 76=TS,=EK y agrupados.• 88,89=agrupados.

RESULTADOS

2. PFGE patterns of SfiI (REAG-S) with dendogram for C.albicans isolates:

2.1 Intrapatient PFGE analysis:

•12 pacientes relacionados.•30,89 no identicos pero si relacionados genticamente.

2.2 Inter-patient PFGE analysis:

• Apoya agrupamiento realizado en primera prueba, logra resolver 17 bandas.

RESULTADOS3. PFGE patterns of BssHII(REAG-B) with dendogram for C.albicans isolates:Observación de mayor diversidad3.1 Intra-patient PFGE analysis:

•11 de 14 con secuencias múltiples, pacientes individuales con bandas idénticas.•14= ≥95% relacionados genéticamente. 9 pacientes recuperados=genotipo

3.2 Inter-patient PFGE analysis:Resolvió 26 bandas, mas discriminatorio y apoya agrupación de método 1.

RESULTADOS

Table 1. Inter-patient comparisons

Method EK REAG-S REAG-B (%) (%) (%)

Patients 1 vs. 21 100 79 78Patients 1 vs.15 100 89 78Patients 15 vs. 21 100 79 93Patients 15 vs. 24 100 98 94Patients 41 vs. 70 100 67 78Patients 41 vs. 76 100 67 78Patient 70 vs. 76 100 86 83Patients 88 vs. 89 (day 2) 100 99 98Patients 88 vs. 89(day 18) 96 96 95

Similaridad genética entre pacientes:

• 100%=idénticas genéticamente

• ≥95% y <100%= similares genéticamente

• <95%= diferentes genéticamente

DISCUSSION

Author’s Name What the author said?Is it related with the study?

Adair CG, Gorman SP, Feron BM, et al.

The endotracheal tube can serve as a reservoir for pathogens in VAP patients and can facilitate the transport of pathogens to the lungs.

Shin JH, Park MR, Song JW, et al.

The low rate of microevolution of C. albicans in ICU patients was attributed to insufficient time for strains to diversify.

YES NOT

DISCUSSION

Author’s Name What the author said?Is it related with the study?

Voss A, Pfaller MA, Hollis Rj, et al.

Comparison of the strains from different patients indicates that there may be a possibility of acquisition of the organism from environment after admission to the hospital. That’s why PFGE typing methods may be used to detect nosocomial transmission.

YES NOT

DISCUSSION

Author’s Name What the author said?Is it related with the study?

Chen KW, Chen YC,Lo HJ, et al.

MLST have been shown to be more discriminatory for C. albicans, but no other Candida species.

YES NOT

CONCLUSIONS

• The using of intravascular catheters, surgical procedures and endotracheal tube, can serve as a conduct for C. albicans transmission to the lower airway in ICU patients.

• There is a low possibility of finding the exogenous origin of the C. albicans strains, but there is a very plausible possibility of finding genetic similarities between the dental plaque, bronchoalveolar lavage and tracheal secretion samples of the same patient.

CONCLUSIONS

• Knowing that MLST is the most discriminatory method used for C. albicans but not for other Candida species, there has been shown in this study that working with the three PFGE typing methods could be an easily way to demonstrate the high diversity of intra and inter-patient strains.

• Even though C. albicans is an inoffensive but opportunistic pathogen that can cause high percentage of morbidity and mortality at hospitals. It is necessary to learn about its route of transmission inside the patient, so then you can determine if there is an endogenous or exogenous origin of the strain and stop it.

CAROLINA SEVERICHE MENA

SUSANA RIOS ECHAVARRIA