RESUMO
Background and Aim: Klebsiella pneumoniae is one of the most common causes of clinical and asymptomatic mastitis in dairy cattle, as well as in milk and dairy products that affect milk quality. Mastitis caused by K. pneumoniae is even more serious due to its poor response to antibiotic therapy. The aim of this study was to detect and identify the presence of K. pneumoniae in milk and dairy products produced in Libya. Materials and Methods: A total of 234 samples were randomly collected from various locations in Libya. Samples were examined for the presence of K. pneumoniae using conventional cultural techniques, including cultivation in violet red bile agar plus 4-methylumbelliferyl-ß-D-glucuronide broth and CHROM agar, followed by polymerase chain reaction identification and partial sequencing of 16S rRNA. Results: Of the 234 samples of milk and dairy products collected, 16 (6.8%) isolates revealed mucoid colonies on agar media that were phenotypically suggested to be K. pneumoniae. Identification of isolates was confirmed using molecular techniques (16S rRNA). Among the examined samples, K. pneumoniae was recovered from camel's milk, raw cow's milk, raw fermented milk, Maasora cheese, Ricotta cheese, soft cheese, full cream milk powder, milk powder infant formula, cereal baby food, and growing-up formula. Antibiotic susceptibility testing was performed on 12 of the 16 K. pneumoniae isolates, and the results showed that K. pneumoniae isolates were resistant to more than eight antibiotics; interestingly, two isolates showed metallo-beta-lactamase (MBL) production. Conclusion: K. pneumoniae is considered a risk to human health because many of these products do not comply with the microbiological criteria of international and/or Libyan standards. This study emphasized the relationship between K. pneumoniae and raw milk, cheese, milk powder, and infant milk retailed in Libya. There is a need to take the necessary measures to ensure effective hygiene practices during production in dairy factories, handling, and distribution on the market, in particular at a small local production scale.
RESUMO
Background: Cronobacter sspecies are the most significant foodborne pathogen in infant milk formula (IMF). These pathogens have been incriminated in severe forms of neonatal meningitis, sepsis, and necrotizing enterocolitis with a high mortality rate. Aim: This study was performed to elucidate the effect of heat stress on Cronobacter spp. (C. sakazakii and C. pulveris) in reconstituted IMF (RIMF). Methods: The reconstituted formula was inoculated with five C. sakazakii isolates and four C. pulveris isolates separately. The nine isolates of Cronobacter spp. were heated in RIMF at 48°C, 52°C, 56°C, 60°C, 64°C, and 66°C. The D- and z-values were determined by using linear regression analysis. Results: The D-values of all isolates of C. sakazakii (CS1, CS3, CS4, CS5, and CS6) at 48°C, 52°C, 56°C, 60°C, 64°C, and 66°C were in the ranges 7.29-23.47, 2.77-15.50, 0.62-1.04, 0.62-1.02, 0.62-1.00, 0.62-1.00 minutes, respectively; while, the z-values extended from 2.50°C to 4.28°C. The D- values of C. pulveris isolates (CP1, CP2, CP3, CP4) were in the ranges 7.60-22.32, 1.42-8.45, 0.62-1.08, 0.62-0.78, 0.62-0.78, 0.62-0.79 minutes at 48°C, 52°C, 56°C, 60°C, 64°C, 66°C, respectively and the calculated z-values ranged from 3.33°C to 4.89°C. Conclusion: This study may contribute to improving the understanding of the behavior of C. sakazakii and C. pulveris isolates in RIMF at various heat stress temperatures and may participate in the effective control of these pathogens in infant food production.