A validated miniaturized MPN method, based on ISO 6579:2002, for the enumeration of Salmonella from poultry matrices

Abstract

Aims: To validate the effectiveness of a miniaturized most probable number method (mMPN) in enumerating Salmonella from poultry matrices. Methods and Results: A MPN was developed, based on the ISO 6579:2002 method using modified semi‐solid Rappaport–Vassiliadis media as the sole selective medium. The validation of the mMPN was shown to not differ significantly from, at the 95% confidence level (Student’s t‐test P = 0·357) to, the traditional 9‐tube MPN (tMPN) using pure cultures of Salmonella ser. Typhimurium, Infantis, Montevideo, Muenster and Salmonella subsp II 1,4,12,27:b:[e,n,x] (Sofia). The validation of naturally and artificially contaminated poultry matrices (carcasses, scald tank water, faeces, caeca and feed) showed that detection using the mMPN compared well to the ISO 6572:2002; sensitivity (92%), specificity (97%) and agreement (KAPPA 0·72). The quantitative comparison between the tMPN and mMPN methods showed that 92% of enumerations were less than ±1 log different (Student’s t‐test = 0·13). Financial analysis showed that the mMPN required 64% less media and 56% less labour than the tMPN. Conclusion: The mMPN is a consistent, easy to automate method for the enumeration of Salmonella from different poultry matrices. Significance and Impact of Study: The miniaturized MPN reduces the material and labour cost of the method and enables the uniform and accurate measurement of the effectiveness of intervention strategies in the control of Salmonella colonization of poultry.

Prevalence, Numbers and Antimicrobial Susceptibilities of Salmonella Serovars and Campylobacter spp. in Retail Poultry in Phnom Penh, Cambodia

“…Enumeration of Salmonella: A semi-quantitative approach using modified semisolid Rappaport Vassiliadis (MSRV) agar was applied [18] by practice successive dilutions and by aspired 0.5 ml of aliquot (1/10) from the 1st serial to 4th serial of wells. After incubation the microplates at 37°C for 20 hr, 20 µl of each dilution was peripheral transferred to the 2nd microplate to corresponding wells filling with 2 ml of MSRV media.…”

Número mais provável miniaturizado e microbiologia convencional para isolamento de Salmonella spp. em abatedouros de frangos de corte

“…para avalição da contaminação em abatedouros por métodos qualitativos já é realizada, mas a quantificação da bactéria não é rotineiramente empregada, uma vez que técnicas tradicionais de enumeração como o Número Mais Provável (NMP), que utilizam séries de tubos múltiplos, demandam tempo, pessoal e recursos financeiros elevados (Cavada et al 2010), dificultando sua aplicação em programas de monitoria. Métodos de quantificação de bactérias por Número Mais Provável miniaturizado (mNMP) são citados como uma alternativa mais rápida e menos trabalhosa para enumeração de salmonelas (Fravallo et al 2003, Pavic et al 2009) mas foram aplicados em amostras artificialmente contaminadas para validação destas técnicas.…”

Applicability of Micro Inoculation Culture (MIC) for Rapid Monitoring of Total Coliform Contaminants in the Food Industry

“…The volume of media (CCA) and the amount of disposable materials (glass Petri dishes and 96 micro-deep wells) were monitored. Pavic et al [3] and Chenu et al [16] recommended the method for calculating the operating cost with slight modification. The times to analyze 36 samples by ISO 4833-1:2013 and the microscale technique were measured.…”

“…This technique was shown to be superior to the conventional streak plate or spread plate techniques when handling large volume industrial samples. Previous studies using multiple microwell techniques (both 24-and 96-well formats) for viable cell counts of various bacteria have proven practical for routine inspection of industrial food and environmental samples, because large numbers of samples can be handled effectively saving both money and analytical time [3,16,17]. In this paper, several common protocols to estimate coliforms and E. coli were evaluated.…”