Molecular characterization of antimicrobial resistance in non-typhoidal salmonellae associated with systemic manifestations from India

Abstract

Extended-spectrum cephalosporins and fluoroquinolones are essential antimicrobials for treating invasive salmonellosis, although emerging resistance to these antimicrobials is of growing concern, especially in India. Therefore, a study was conducted to characterize the antimicrobial susceptibility phenotypes, types of extended-spectrum b-lactamase (ESBL) gene plasmids and serological relationships of 21 non-typhoidal Salmonella isolates from patients who attended three different hospitals in India from 2006 to 2008. The isolates were cultured from stool, blood and cerebrospinal fluid samples obtained from patients presenting with diarrhoea and accompanying systemic manifestations such as fever, vomiting and meningism. Non-typhoidal Salmonella isolates were investigated using serotyping and antimicrobial susceptibility testing. PCR screening was also performed to detect the b-lactamase, qnr and aac(69)-Ib-cr genes and class 1 integrons. Sequencing for quinolone resistance mutations and plasmid replicon typing were also performed. An antimicrobial resistance microarray was used for preliminary screening and identification of bla TEM and bla SHV genes, and phenotypic testing for the presence of efflux pumps was also performed. Ten out of 21 isolates (48 %) possessed the extended-spectrum cephalosporin resistance phenotype, with PCR amplification and sequencing revealing that isolates possessed TEM-1, SHV-12, DHA-1, OXA-1-like and CTX-M-15 ESBL genes. FII s plasmid replicons were detected in seven isolates (33 %). The involvement of efflux pumps was detected in four isolates (19 %) resistant to ciprofloxacin. It was concluded that SHV-12-carrying Salmonella serotype Agona may play an important role in ESBL-mediated resistance in nontyphoidal salmonellae in India. The very high percentage (48 %) of ESBL-producing non-typhoidal salmonellae isolated from these patients represents a real and immediate challenge to the effective antimicrobial therapy of Salmonella infections associated with systemic manifestations. Continued surveillance for the presence of ESBL-producing (non-typhoidal) salmonellae in India is essential. INTRODUCTIONNon-typhoidal Salmonella is one of the principal pathogens implicated in food-borne gastroenteritis worldwide. In severe infections such as meningitis and septicaemia, antibiotic treatment is essential, with extended-spectrum cephalosporins being used preferentially to treat salmonellosis in children (Threlfall, 2002). However, treatment failures due to the in vivo acquisition of extended-spectrum b-lactamase (ESBL) or fluoroquinolone resistance genes in Salmonella isolates are now well established (Whichard et al., 2007). Salmonella species resistant to extendedspectrum cephalosporins have been known since 1988 (Hammami et al., 1991) Fluoroquinolone resistance is also a growing problem in non-typhoidal salmonellae, with the first report of ciprofloxacin resistance in Salmonella enterica infection (eventually leading to treatment failure) being published in 1990 (Piddock et al., 1990). Sinc...

First case report of blood and urine cultures positive bacteraemia by Salmonella enterica serotype Choleraesuis from India

“…Another report has documented the isolation of S. Worthington and S. Weltevreden from neonatal sepsis cases from Pune and South India, respectively (Muley et al, 2004;Patil et al, 2006). In Pondicherry, S. Agona and S. Typhimurium have been isolated from adult patients complaining of diarrhoea and fever (Menezes et al, 2010). So far, to the best of our knowledge, this is the first report from India of human bacteraemia caused by S. Choleraesuis, in which isolates were recovered both from blood and urine samples.…”

Non-typhoidal Salmonella isolates from livestock and food samples, in and around Kolkata, India

“…Variable percentage resistance for third generation cephalosporins was reported from China (1.6%), Romania (11.4%) and the US (16%) [5,6,17]. This emerging resistance to fluoroquinolones and third generation cephalosporins is alarming since these are the current drugs of choice for treating invasive salmonellosis in humans [24][25][26][27].…”

“…MDR S. Senftenberg isolated from goat meat showed resistance to both fluoroquinolones (MIC of ciprofloxacin: >32 µg/mL; ofloxacin: >32 µg/ mL; norfloxacin: >256 µg/mL) and third generation cephalosporins (MIC of cefotaxime: >256 µg/mL; ceftriaxone: >256 µg/mL and ceftazidime: 16 µg/ mL) ( Table 2). NTS serovars like S. Agona, S. Choleraesuis, S. Enteritidis and S. Typhimurium showing resistance to both these groups of drugs is on a rise and have been reported from other countries including India [24][25][26][27].…”

Non-Typhoidal Salmonella Gastroenteritis at a Diarrheal Hospital in Dhaka, Bangladesh, 1996–2011

“…An estimate of the burden of NTS disease in South Asia extrapolated from a single study of returning travelers to Sweden suggested an incidence of 470 per 100,000 personyears, 3 but that number is likely not representative of the incidence within the local population. Most reports from South Asia have been limited to surveillance of antimicrobial resistance patterns 4,5 and circulating serotypes. 6 Studies on the burden of illness and risk factors for disease are limited.…”