Survival dan pertumbuhan Cronobacter sakazakii dan Lactobacillus selama rekonstitusi susu formula

Abstract

Cronobactersakazakii (Enterobacter sakazakii) is an emerging foodborne pathogenassociated with powdered infant formula(PIF). The bacterium has been known to cause necrotizing enterocolitis(NEC), meningitis, and sepsis in neonates, especially to those born prematurely and or with low birth weight. C.sakazakiicould be found and survive in PIFas a residual contamination during drying or filling (after pasteurization process) and reconstitution practice in household or hospitals.Recently, somePIF product is being added with Lactobacillus as probiotics, therefore the reconstitution temperature may affect both the Lactobacillus and C. sakazakii. The objectives of this study are to study (1)the influence of various temperature of the water (30, 50, and 70oC) used for reconstitution on (a) the survival and growth of C. sakazakii in PIF, (b) the survival and growth of C. sakazakii and Lactobacillus R23 present together in PIF, and (2) to determine selective enumeration media of C. sakazakii and Lactobacillus R23 when both are present in PIF. A preliminary study was conducted for rapid screening of six isolates to obtain two heat tolerant C. sakazakii isolates by using heat treatment at 54oC for 32 minutes. The main study was evaluation of survival and growth of C. sakazakii YR c3a in PIF followingreconstitution at the above temperatures in the absence or presence of Lactobacillus R23 for up to eight hours. C. sakazakii YR c3a and DES b7b were selected as the more heat tolerant. Reconstitution at 30 and 50 oC did not influence survival and growth of C. sakazakii for up to 8 h hang time.Two log reductionsof C. sakazakii occurred in PIF reconstituted with water at 70oC.At 30 oC, presence of Lactobacillus R23 in PIF also did not affect the survival and growth of C. sakazakii upon reconsitution at irrespective of the initial load ratio. Meanwhile presence of Lactobacillus did not affect C. sakazaki upon reconstitution at 50 oC when the ratio of LactobacillusR23 : C. sakazakiiYR c3a was 1:1, but growth of C. sakazakii YR c3a decreased following reconstitution when ratio of the two bacteria was 103:1.Reconstitution at 70 oC reduced the number of C. sakazakii YR c3a and DES b7b by 2.51 and 2.48 log CFU/ml, respectively. In PIF containing Lactobacillus, regardless of the ratio, Lactobacillus R23 and C. Sakazakii YR c3adecreased for up to <1,00 log CFU/ml and to 1,40 log CFU/ml, respectively. Following reconstitution at this temperature, the growth of C. sakazakiiYR c3a started tobe observed 4 h afterward while Lactobacillus R23 started to increase 2 h afterward.