Prevalence And Control Of Cronobacter Spp.in Production Processes Of Infant Formula Goat Milk Powder Factories

Cronobacter spp. can cause necrotizing enterocolitis, meningitis and septicaema with fatality rates more than 50%. For many reports showed that the contaminated infant formula was the major channels of neonatal infection incident, how to prevent Cronobacter spp.contaminated infant formula should be essential for infant health protection, although it was not certain the host and propagation models of this bacterial.This study aimed to investigate Cronobacter spp. contamination status of all aspects of infant formula goat milk powder production process with 60-weeks sampling time, and to speculate the potential contamination pathway of Cronobacter spp. in the factory by molecular typing of isolates. At last the effectiveness of the existing workshop sterilization measures was evaluated in order to provide evidence focus on prevention and control of the bacterial. The main conclusions are as follows:(1) The total samples(1560) were collected from different production processes in goat milk powder factory A(150), B(510), C(408) and D(492) in Shaanxi province, China. There were 33(24.6%) positive sampling points which 48 isolates collected from. The prevalence rates of samples in factory A, B, C and D were 16.0%(24/150), 1.0%(5/510), 1.0%(4/408),3.0%(15/492), respectively. And the prevalence rates to sampling points in factory A, B, C and D were 52.0%(13/25), 14.7%(5/34), 11.8%(4/34), 26.8%(11/41), respectively.(2) The order of workshop contamination rate was air filtration system 4.8% > packaging rooms 3.8% > fluidized bed rooms 3.5% > spray drying rooms 3.0%. All of the four different sample types: swabs samples(3.1%), plants internal air samples(6.6%), liquid samples(0.7%)and powder samples(1.7%) were detected Cronobacter spp.. The highest contamination rate of different sample types were: milk evaporating plant and packaging rooms-8.9%(air samples), spray drying rooms-4.2%(swabs), intermediate powder-4.4%(powder samples),evaporated milk-2.2%(liquid samples).(3) 48 isolates were identified by PCR. The results showed that all of the isolates were C.sakazakii(100.0%) which reported as the predominant species of Cronobacter spp.. No C.turicensis, C. condimenti, C. malonaticus, C. muytjensii, C. universalis and C. dublinensis isolates were found.(4) 48 isolates of Cronobacter sakazakii in four factoies(A, B, C, D) are categorized into15 types, which 35(72.9%) strains of bacteria distribution in Y1-Y5 type. 3 strains isolated from factory B and 4 strains isolated from factory C belong to same type Y5, thus the isolates from these two factories showed serotyping crossing. The mainstream type of Cronobacter sakazakii showed different potential pollution routes: Type Y1- the bacteria which concentrated in the air of milk evaporating plant was brought by employees into the clean operation area and polluted intermediate powder and unpacked finished powder. Type Y2-the bacteria was brought by air filtration system into the clean operation area and has not been detected in the final product. Y3- the bacteria was brought by employees into the clean operation area and has not been detected in the final product. Y4- the bacteria was brought by air filtration system or employees into the clean operation area and has not been detected in the final product.(5) The air bacterial inactivation rate with different density lactic acid fumigation was 5times(92.10%) > 10 times(85.42%) > 0 times(77.14%). Cronobacter sakazakii inactivation rate with different density lactic acid fumigation was 5 times(88.89%) > 10 times(83.33%) >0 times(76.19%). The two sterilization rate showed same trend, so the 5 times dilution of lactic acid was suggested applied for fumigation. The killing rate of air bacteria increasing from 46.16% to 62.61% by time increased from 30 min to 60 min with ultraviolet radiation. On the contrary, UV irradiation should be the preferred method of surface sterilization, because all of the Cronobacter sakazakii on the surface losing life(100% killing rate) with this method. In summary, prevention and control of Cronobacter sakazakii in the production processes shall be considered many aspects, such as man, machine, material, method and environment with multi-measures.