Molecular typing of multidrug-resistant Salmonella Blockley outbreak isolates from Greece

Human infections due to Salmonella Blockley, a rare serotype in South Africa: a case report

BACKGROUND

Infections due to nontyphoidal Salmonella have increased worldwide over the last couple of decades. Salmonella enterica serotype Blockley (Salmonella Blockley) infections is associated with chickens and is a rarely isolated serotype in human infections in most countries.

CASE PRESENTATION

We report a case of human infections due to Salmonella Blockley in KwaZulu-Natal, South Africa in 2011. Three African males (aged 4, 14 and 16) presented to a clinic with diarrhoea, stomach cramps and headache. They started experiencing signs of illness a day after they consumed a common meal, consisting of meat, rice and potatoes. Stool specimens from the patients cultured Salmonella Blockley. The strains showed an indistinguishable pulsed-field gel electrophoresis pattern.

CONCLUSION

This is the first recorded case of human infections due to Salmonella Blockley in South Africa.

The prevalence of multidrug resistance is higher among bovine than human Salmonella enterica serotype Newport, Typhimurium, and 4,5,12:i:- isolates in the United States but differs by serotype and geographic region

Salmonella represents an important zoonotic pathogen worldwide, but the transmission dynamics between humans and animals as well as within animal populations are incompletely understood. We characterized Salmonella isolates from cattle and humans in two geographic regions of the United States, the Pacific Northwest and the Northeast, using three common subtyping methods (pulsed-field gel electrophoresis [PFGE], multilocus variable number of tandem repeat analysis [MLVA], and multilocus sequence typing [MLST]). In addition, we analyzed the distribution of antimicrobial resistance among human and cattle Salmonella isolates from the two study areas and characterized Salmonella persistence on individual dairy farms. For both Salmonella enterica subsp. enterica serotypes Newport and Typhimurium, we found multidrug resistance to be significantly associated with bovine origin of isolates, with the odds of multidrug resistance for Newport isolates from cattle approximately 18 times higher than for Newport isolates from humans. Isolates from the Northwest were significantly more likely to be multidrug resistant than those from the Northeast, and susceptible and resistant isolates appeared to represent distinct Salmonella subtypes. We detected evidence for strain diversification during Salmonella persistence on farms, which included changes in antimicrobial resistance as well as genetic changes manifested in PFGE and MLVA pattern shifts. While discriminatory power was serotype dependent, the combination of PFGE data with either MLVA or resistance typing data consistently allowed for improved subtype discrimination. Our results are consistent with the idea that cattle are an important reservoir of multidrug-resistant Salmonella infections in humans. In addition, the study provides evidence for the value of including antimicrobial resistance data in epidemiological investigations and highlights the benefits and potential problems of combining subtyping methods.

Repeated occurrence of diverse extended-spectrum beta-lactamases in minor serotypes of food-borne Salmonella enterica subsp. enterica

Screening of Greek nontyphoid salmonellae from 2000 to 2002 yielded three extended-spectrum beta-lactamase (ESBL)-producing human isolates. Salmonella enterica serotype Brandenburg harbored a multiresistant SHV-5 gene-carrying plasmid. S. enterica serotype Blockley and S. enterica serotype Hadar harbored a TEM-52 gene-carrying plasmid. An S. enterica serotype Virchow strain producing plasmid-mediated CTX-M-32 was isolated twice from poultry end products. All ESBL plasmids were self-transferable and carried by clones currently common in Greece.

Severe acute respiratory syndrome: report of treatment and outcome after a major outbreak

BACKGROUND

The outcome is reported of a prospective uncontrolled study based on a stepwise treatment protocol during an outbreak of severe acute respiratory syndrome (SARS) in Hong Kong.

METHOD

One hundred and thirty eight patients were treated with broad spectrum antibiotics, a combination of ribavirin and low dose corticosteroid, and then intravenous high dose methylprednisolone according to responses. Sustained response to treatment was defined as (1) defervescence for > or =4 consecutive days, (2) resolution of lung consolidation by >25%, and (3) oxygen independence by the fourth day without fever. Patients with defervescence who achieved either criterion 2 or 3 were classified as partial responders. Patients who fell short of criteria 2 and 3 were non-responders.

RESULTS

Laboratory confirmation of SARS coronavirus infection was established in 132 (95.7%). None responded to antibiotics but 25 (18.1%) responded to ribavirin + low dose corticosteroid. Methylprednisolone was used in 107 patients, of whom 95 (88.8%) responded favourably. Evidence of haemolytic anaemia was observed in 49 (36%). A high level of C-reactive protein at presentation was the only independent predictor for use of methylprednisolone (odds ratio 2.18 per 10 mg/dl increase, 95% confidence interval 1.12 to 4.25, p = 0.02). Thirty seven patients (26.8%) required admission to the intensive care unit and 21 (15.2%) required invasive mechanical ventilation. There were 15 deaths (mortality rate 10.9%), most with significant co-morbidities, whereas 122 (88.4%) had been discharged home 4 months after the outbreak onset.

CONCLUSION

The use of high dose pulse methylprednisolone during the clinical course of a SARS outbreak was associated with clinical improvement, but randomised controlled trials are needed to ascertain its efficacy in this condition.