Lecturer, Food Microbiology and Biotechnology. Specialist: Food Safety, Quality Management and Risk Analysis; Molecular Biology Techniques; Antimicrobial Resistance in Food Bacteria; Biostatistics




Gitahi, MG, Wangoh J, Njage PMK.  2012.  Microbial Safety of Street Food in Industrial Area, Nairobi. Abstract

Street food play a significant role in feeding urban population with cheap accessible and nutritious foods. Most street foods vendors are not trained on food hygiene and safety........

Jans, C, Gerber A, Bugnard J, Njage PMK, Lacroix C, Meile L.  2012.  Novel Streptococcus infantarius subsp. infantarius variants harboring lactose metabolism genes homologous to Streptococcus thermophilus. Abstract

Streptococcus infantarius subsp. infantarius belongs to the Streptococcus bovis/Streptococcus equinus complex (SBSEC) commonly associated with human and animal infections. We elucidated the lactose metabolism of S. infantarius subsp. infantarius predominant in African fermented milk products. S. infantarius subsp. infantarius isolates (n = 192) were identified in 88% of spontaneously fermented camel milk suusac samples (n = 24) from Kenya and Somalia at log10 8.2–8.5 CFU mL−1. African S. infantarius isolates excreted stoichiometric amounts of galactose when grown on lactose, exhibiting a metabolism similar to Streptococcusthermophilus and distinct from their type strain. African S. infantarius subsp. infantarius CJ18 harbors a regular gal operon with 99.7–100% sequence identity to S. infantarius subsp. infantarius ATCC BAA-102T and a gal-lac operon with 91.7–97.6% sequence identity to S. thermophilus, absent in all sequenced SBSEC strains analyzed. The expression and functionality of lacZ was demonstrated in a β-galactosidase assay. The gal-lac operon was identified in 100% of investigated S. infantarius isolates (n = 46) from suusac samples and confirmed in Malian fermented cow milk isolates. The African S. infantarius variant potentially evolved through horizontal gene transfer of an S. thermophilus-homologous lactose pathway. Safety assessments are needed to identify any putative health risks of this novel S. infantarius variant.

Njage, PMK, Dolci S, Jans C, Wangoh J, Lacroix C, Meile L.  2012.  Ampicillin Resistance And Extended Spectrum Β-lactamases In Enterobacteriaceae Isolated From Raw And Spontaneously Fermented Camel Milk. Abstract

The prevalence of ampicillin resistance and extended-spectrum β-lactamases(ESBL)in the dominant Enterobacteriaceae from raw and spontaneously fermented camel milk (suusac) in Kenya and Somalia was characterized both phenotypically and genotypically. Globally important SHV and CTX-M-type extended spectrum β–lactamases (ESBLs)were tested. The Enterobacteriaceaebelonged to 15 species from 10 genera. Dominant isolates wereEscherichia coli (50), Klebsiellapneumoniasubsp.pneumoniae (35) and Enterobactersakazakii (20).Salmonella arizonae, Serratia odorifera and E. coli occurred at viable counts greater than 8 log cfu/ml. ESBL was studied f or 96 E. coli, K. pneumoniasubsp. pneumoniae andE.sakazakii. Total of 61 (63% )isolates consisting of 46 (48%) ofE. coli, 45 (46%)K.pneumonia subsp.Pneumoniaand 16 (7%) E.sakazakiiwere resistant to ampicillin.blaSHV ,blaCTX-M-3-like blaCTX-M-14-like genes were detectedin 37 (60%), 25 (40%) and 11 (18%) of theEnterobacteriaceae isolates respectively.K.pneumonia subsp.pneumoniae harbored majority of these bla genes (74%)with1 strain possessing all 3 genes and 13 harbouring both bla SHV and bla CTX-M-3-like genes. Thediversity ofEnterobacteriaceae in camel milk calls for improvedhandling of camel milk.The ESBLgenes intheisolates fromremotesemi-arid regions emphasises the global antimicrobial resistanceproblemamong Enterobacteriaceae



Njage, PMK;, Jans C;, Wangoh J;, Farah Z;, Lacroix C;, Meile. L.  2010.  Microbial biodiversity of camel milk and fermented camel milk products: technology, hygiene and safet.
Njage, PMK;, Jans C;, Wangoh J;, Farah Z;, Lacroix C;, Meile L.  2010.  iodiversity And Genotyping Of Staphylococci Isolated In Raw And Fermented Camel Milk In East Africa..



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