Vancomycin-resistant Staphylococcus aureus isolated from camel meat and slaughterhouse workers in Egypt

Abstract

Background: The emergence of vancomycin-resistant Staphylococcus aureus (VRSA) represents a challenge for the treatment of staphylococcal infections in both human and animals worldwide. Although VRSA has been detected in several animal species worldwide, data on the bacterial prevalence in dromedary camels and workers in camel slaughterhouses are scarce.

Methods: We investigated meat samples from 200 dromedary camel carcasses from three different abattoirs that were being prepared to be sent to the markets. Twenty hand swabs were voluntarily collected from the workers in the same abattoirs. Isolation and identification of the bacterial specimens from the samples were performed using conventional cultural techniques and biochemical identification and were confirmed by PCR amplification of the nuc gene. Antimicrobial susceptibility against nine antimicrobial agents commonly used in human and camels was tested using the disc diffusion method, and genetic analysis was performed by evaluating the mecA gene in phenotypically oxacillin (OXA)- and cefoxitin (FOX)-resistant isolates. The resistance of S. aureus to vancomycin (VAN) was tested by broth microdilution and confirmed by PCR targeting the vanA and vanB genes. The vanA and vanB genes were sequenced.

Result: S. aureus was detected in both camel meat (29/200, 14.5%) and in abattoir workers (11/20, 55%). Of the collected samples, 27% (8/29, camel) and 54% (6/11, human) were identified as VRSA.All VRSA isolates carried both the vanA and vanB genes. Additionally, all VRSA isolates were also classified as methicillin-resistant S. aureus (MRSA). The vanA amplicons of the isolates from human and camel meat were homologous and clustered with a Chinese reference isolate sequence.

Conclusion: This study demonstrated that VRSA is present in camel abattoirs in Egypt. Zoonotic transmission between animals and human is probable and reflects both a public health threat and a food safety concern.

Keywords: Abattoir; Dromedary camels; Egypt; Human; S. aureus; VRSA.

Fig. 1

Amplified PCR products of nuc gene at (270 bp). Lane M: 100 bp ladder, Lane 1 to 6 positive to Staphylococcus aureus

Fig. 2

Amplified PCR products of mecA gene at (583 bp). Lane M: 100 bp ladder, Lane 1 to 6. Positive to mecA gene; results for 6 among the 25 isolates

Fig. 3

Amplified PCR products of VanA gene at (713 bp). Lane M: 100 bp ladder, Lane 1: positive control. Lane 2 to 6. Positive to vanA gene of VRSA isolates; results for 5 among the 14 VRSA isolates

Fig. 4

Amplified PCR products of VanB gene at (430 bp). Lane M: 100 bp ladder, Lane 1, positive control, lane: 2 to6 positive to vanB gene of VRSA isolates; results for 5 among the 14 VRSA isolates

Fig. 5

Neighbour joining tree showing the relationship between the nucleotide sequences of the partial coding regions of VanA gene of S. aureus .The Evolutionary analysis was performed with MEGA version 7