Molecular detection of methicillin heat-resistant Staphylococcus aureus strains in pasteurized camel milk in Saudi Arabia.

Antibiotic- and heat-resistant bacteria in camel milk is a potential public health problem. Staphylococcus aureus (S. aureus) is an opportunistic pathogen in humans, dairy cattle and camels. We characterized the phenotype and genotype of methicillin-resistant staphylococcal strains recovered from pasteurized and raw camel milk (as control) distributed in the retail markets of Saudi Arabia. Of the 100 samples assessed between March and May 2016, 20 S. aureus isolates were recovered from pasteurized milk, 10 of which were resistant to cefoxitin, and as such, were methicillin-resistant. However, raw camel milk did not contain methicillin-resistant S. aureus (MRSA). Antimicrobial susceptibility tests showed that the resistance ratio for other antibiotics was 60%. We performed a polymerase chain reaction (PCR) assay using primers for the methicillin-resistant gene mecA and nucleotide sequencing to detect and verify the methicillin-resistant strains. Basic local alignment search tool (BLAST) analysis of the gene sequences showed a 96-100% similarity between the resistant isolates and the S. aureus CS100 strain's mecA gene. Ten of the methicillin-resistant isolates were heat-resistant and were stable at temperatures up to 85°C for 60 s, and three of these were resistant at 90°C for 60 or 90 s. The mean decimal reduction time (D85-value) was 111 s for the ten isolates. Sodium dodecyl sulfate (SDS)/polyacrylamide gel electrophoresis (PAGE) showed that there was no difference in the total protein profiles for the ten methicillin heat-resistant S. aureus (MHRSA) isolates and for S. aureus ATCC 29737. In conclusion, a relatively high percentage of the tested pasteurized camel milk samples contained S. aureus (20%) and MHRSA (10%).

Plant-Derived Polyphenols Interact with Staphylococcal Enterotoxin A and Inhibit Toxin Activity.

This study was performed to investigate the inhibitory effects of 16 different plant-derived polyphenols on the toxicity of staphylococcal enterotoxin A (SEA). Plant-derived polyphenols were incubated with the cultured Staphylococcus aureus C-29 to investigate the effects of these samples on SEA produced from C-29 using Western blot analysis. Twelve polyphenols (0.1-0.5 mg/mL) inhibited the interaction between the anti-SEA antibody and SEA. We examined whether the polyphenols could directly interact with SEA after incubation of these test samples with SEA. As a result, 8 polyphenols (0.25 mg/mL) significantly decreased SEA protein levels. In addition, the polyphenols that interacted with SEA inactivated the toxin activity of splenocyte proliferation induced by SEA. Polyphenols that exerted inhibitory effects on SEA toxic activity had a tendency to interact with SEA. In particular, polyphenol compounds with 1 or 2 hexahydroxydiphenoyl groups and/or a galloyl group, such as eugeniin, castalagin, punicalagin, pedunculagin, corilagin and geraniin, strongly interacted with SEA and inhibited toxin activity at a low concentration. These polyphenols may be used to prevent S. aureus infection and staphylococcal food poisoning.

[Staphylococcal food poisoning and MRSA enterocolitis].

Staphylococcal food poisoning is a gastrointestinal illness. It is caused by eating foods contaminated with enterotoxins produced by Staphylococcus aureus. The enterotoxins are fast acting, sometimes causing illness within one to six hours. Patients typically experience nausea, vomiting, stomach cramps, and diarrhea. Diagnosis of staphylococcal food poisoning is generally based only on the symptoms of patients. The treatments for these patients are rest and plenty of fluids. Antibiotics are not useful in treating this illness. On the other hand, methicillin resistant Staphylococcus aureus (MRSA) enteritis and colitis caused by microbial substitution with administration of antibiotics is aggressive and sick with severe diarrhea. The treatment of those patients are as follows; antibiotics now in use are stopped and oral administration of vancomycin is started as soon as possible.

Recognition and management of Staphylococcus aureus toxin-mediated disease.

The ubiquitous human pathogen Staphylococcus aureus is capable of producing a formidable range of extracellular toxins that can have significant deleterious effects on the host. Toxic shock syndrome (TSS) results from infection or colonization with a strain of S. aureus that produces staphylococcal enterotoxin(s). The key features of TSS are widespread erythroderma occurring in association with profound hypotension and multiple organ dysfunction. As morbidity and mortality from TSS are appreciable, early recognition of TSS combined with intensive supportive management is critical. Staphylococcal foodborne disease (SFD) is caused by contamination of food during preparation or serving by preformed S. aureus enterotoxin(s). Symptom-onset is abrupt and the disease may be severe enough to warrant hospitalization, but it is usually self-limiting and does not require specific antistaphylococcal therapy. Staphylococcal scalded skin syndrome (SSSS) results from colonization or infection with a strain of S. aureus that produces epidermolytic toxin(s). SSSS ranges in severity from trivial focal skin blistering to extensive, life-threatening exfoliation. This review discusses the epidemiology, pathogenesis, diagnosis, and management of TSS, SFD and SSSS.

An outbreak of community-acquired foodborne illness caused by methicillin-resistant Staphylococcus aureus.

Infections with methicillin-resistant Staphylococcus aureus (MRSA) are increasingly community acquired. We investigated an outbreak in which a food handler, food specimen, and three ill patrons were culture positive for the same toxin-producing strain of MRSA. This is the first report of an outbreak of gastrointestinal illness caused by community-acquired MRSA.