Salmonella intracranial infection is infrequently encountered in clinical practice. However, with prompt intervention and appropriate antimicrobial therapy, the outcome is usually favourable. A 56-year-old gentleman who worked as an organic fertilizer production supervisor underwent tumour resection for meningioma located at the left frontal temporoparietal region. The surgical procedure went smoothly, and he has prescribed dexamethasone thereafter. He was discharged well. However, a few days after that he developed a fever associated with pus discharged from the surgical wound. A computed tomography (CT) scan of the brain was performed and it revealed an abscess located at the left frontal temporoparietal subdural and subgaleal regions with adjacent cerebritis. Another craniotomy was done to drain the abscess. The bacterial culture of the pus specimen grew Salmonella Enteritidis. The bacterium was susceptible to ciprofloxacin, ceftriaxone, and amoxicillin-clavulanic acid. Clinical improvement was evident after surgical intervention with an additional 6 weeks of ceftriaxone therapy.
The authors report a case of a 6-week-old baby girl who was admitted to the paediatric ward due to a high fever for 2 days. The patient experienced three fits which took place while in the ward. A brain sonogram showed subdural heterogeneous collection consistent with focal empyema; however, no hydrocephalus or infarction was detected. An urgent Burr hole procedure was performed to remove the collected pus. Both blood and cerebrospinal fluid (CSF) culture grew Salmonella species which remain sensitive to some antibiotics. This strain was sent to the institute of medical research (IMR) for serotyping. The patient was treated with intravenous combination of ceftriaxone and ciprofloxacin for 3 weeks. One week later, IMR sent results that identified the strain as Salmonella enterica serotype Houtenae. Following antibiotic treatment, repeat ultrasound illustrated an improvement of the subdural empyema, and the gram stain of the CSF specimen failed to isolate bacteria.
A 38 year old lady with a previous history of an ovarian cyst, presented with a one week history of fever, diarrhoea and intense localized pain in the left iliac fossa. Laparotomy revealed a left tuboovarian abscess with adherent bowels. Pus from the ruptured cyst grew Salmonella enteritidis. Histologically the cyst wall showed haemorrhagic and degenerate endometriotic features. Recovery was uneventful with cefotaxime and metronidazole.
Salmonella enterica subsp. enterica serovar Typhimurium is one of several well-categorized Salmonella serotypes recognized globally. Here, we report the whole-genome sequence of S Typhimurium strain UPM 260, isolated from a broiler chicken.
Salmonella is as an intracellular bacterium, causing many human fatalities when the host-specific serotypes reach the host gastrointestinal tract. Nontyphoidal Salmonella are responsible for numerous foodborne outbreaks and product recalls worldwide whereas typhoidal Salmonella are responsible for Typhoid fever cases in developing countries. Yet, Salmonella-related foodborne disease outbreaks through its food and water contaminations have urged the advancement of rapid and sensitive Salmonella-detecting methods for public health protection. While conventional detection methods are time-consuming and ineffective for monitoring foodstuffs with short shelf lives, advances in microbiology, molecular biology and biosensor methods have hastened the detection. Here, the review discusses Salmonella pathogenic mechanisms and its detection technology advancements (fundamental concepts, features, implementations, efficiency, benefits, limitations and prospects). The time-efficiency of each rapid test method is discussed in relation to their limit of detections (LODs) and time required from sample enrichment to final data analysis. Importantly, the matrix effects (LODs and sample enrichments) were compared within the methods to potentially speculate Salmonella detection from environmental, clinical or food matrices using certain techniques. Although biotechnological advancements have led to various time-efficient Salmonella-detecting techniques, one should consider the usage of sophisticated equipment to run the analysis by moderately to highly trained personnel. Ultimately, a fast, accurate Salmonella screening that is readily executed by untrained personnels from various matrices, is desired for public health procurement.
Salmonella enterica serovar Paratyphi A is a causative agent of paratyphoid fever. The clinical syndrome caused by paratyphoid fever overlaps with other febrile illnesses and cannot be distinguished from typhoid fever. Conventional methods used for diagnosis are time consuming, costly, and labor-intensive. We evaluated the specificity, sensitivity, and application of a multiplex polymerase chain reaction (PCR) previously developed by the method (Ou, H.Y., Teh, C.S.J., Thong, K.L., et al., J. Mol. Diagn., 9, 624-630, 2007) using 6 S. Paratyphi A, 22 S. Typhi, and 85 other Salmonella serovars as well as 36 non-Salmonella strains. The detection limit of the multiplex PCR was 4 x 10(4) cfu ml(-1). In a blind test of the other 50 strains, this multiplex PCR correctly identified the only S. Paratyphi A in the panel of strains. The sensitivity of this PCR using spiked blood and stool samples was 1 x 10(5) cfu ml(-1) and 2 x 10(5) cfu ml(-1), respectively, but increased to 1 x 10(4) cfu ml(-1) and 2 x 10(3) cfu ml(-1) after 5-h enrichment. We believe that this multiplex PCR is a promising technique for the specific and sensitive detection of S. Paratyphi A in clinical, environmental, and food samples.
Salmonella infections remain a major public health problem in developing countries. The occurrence of infections caused by antimicrobial-resistant Salmonella has been on the rise complicating the available therapeutic options. The study aimed to determine the antibiograms and genotypes of prevalent Salmonella serotypes.
We report here the complete genome sequence of Salmonella enterica subsp. enterica serovar Typhi B/SF/13/03/195 obtained from a typhoid carrier, who is a food handler in Pasir Mas, Kelantan.
The suitability of a PCR procedure using a pair of primers targeting the hilA gene was evaluated as a means of detecting Salmonella species. A total of 33 Salmonella strains from 27 serovars and 15 non-Salmonella strains from eight different genera were included. PCR with all the Salmonella strains produced a 784 bp DNA fragment that was absent from all the non-Salmonella strains tested. The detection limit of the PCR was 100 pg with genomic DNA and 3 x 10(4) c.f.u. ml(-1) with serial dilutions of bacterial culture. An enrichment-PCR method was further developed to test the sensitivity of the hilA primers for the detection of Salmonella in faecal samples spiked with different concentrations of Salmonella choleraesuis subsp. choleraesuis serovar Typhimurium. The method described allowed the detection of Salmonella Typhimurium in faecal samples at a concentration of 3 x 10(2) c.f.u. ml(-1). In conclusion, the hilA primers are specific for Salmonella species and the PCR method presented may be suitable for the detection of Salmonella in faeces.
Salmonella infections across the globe are becoming more challenging to control due to the emergence of multidrug-resistant (MDR) strains. Lytic phages may be suitable alternatives for treating these multidrug-resistant Salmonella infections. Most Salmonella phages to date were collected from human-impacted environments. To further explore the Salmonella phage space, and to potentially identify phages with novel characteristics, we characterized Salmonella-specific phages isolated from the Penang National Park, a conserved rainforest. Four phages with a broad lytic spectrum (kills >5 Salmonella serovars) were further characterized; they have isometric heads and cone-shaped tails, and genomes of ~39,900 bp, encoding 49 CDSs. As the genomes share a <95% sequence similarity to known genomes, the phages were classified as a new species within the genus Kayfunavirus. Interestingly, the phages displayed obvious differences in their lytic spectrum and pH stability, despite having a high sequence similarity (~99% ANI). Subsequent analysis revealed that the phages differed in the nucleotide sequence in the tail spike proteins, tail tubular proteins, and portal proteins, suggesting that the SNPs were responsible for their differing phenotypes. Our findings highlight the diversity of novel Salmonella bacteriophages from rainforest regions, which can be explored as an antimicrobial agent against MDR-Salmonella strains.
There is widespread resistance of Salmonella species to commonly prescribed antimicrobials the world over. We aimed to determine the antimicrobial susceptibility and serovar distribution of non-typhoidal Salmonella (NTS) isolated from blood cultures of Malaysian children. Positive isolates of NTS from blood cultures obtained from children admitted to the pediatric wards of University of Malaya Medical Center (UMMC), a large urban hospital from Kuala Lumpur (1991-2001), and Hospital Kota Bharu (HKB), from the predominantly rural state of Kelantan (1991-1999), Malaysia, were reviewed retrospectively. Serovar distribution and antimicrobial susceptibility were ascertained. A total of 64 and 55 isolates of NTS were obtained from blood cultures of children admitted to UMMC and HKB, respectively. The commonest serovar isolated was Salmonella enteritidis in both centers. The NTS isolated were highly sensitive to the antimicrobials tested: ampicillin 98 per cent, chloramphenicol 98 per cent, gentamicin 97 per cent, trimethoprim-sulfamethoxazole (TMP-SMX) 98 per cent, and ceftriaxone 100 per cent in UMMC; ampicillin 100 per cent, chloramphenicol 87 per cent, kanamycin 100 per cent, streptomycin 96 per cent, TMP-SMX 93 per cent, and tetracycline 89 per cent in HKB. There were only one and five multi-resistant isolates in UMMC and HKB, respectively. In conclusion, NTS isolated from blood cultures of Malaysian children from Kuala Lumpur and Kota Bharu were highly sensitive to commonly prescribed antibiotics. We speculate that this is due to the restriction of sales of antimicrobials in Malaysia except by prescription. Continuing vigilance and frequent antmicrobial surveillance is necessary.
The prevalence of ceftriaxone resistance and the associated genes encoding extended-spectrum β-lactamase (ESBL) was determined in 149 non-duplicate non-typhoidal Salmonella isolated in 2008-2009 from patients in a tertiary care hospital in Kuala Lumpur, Malaysia. The resistance rate to ceftriaxone was 2.7% (2/74) in 2008, 4.0% (3/75) in 2009, and 3.4% (5/149) overall. CTX-M ESBL genes were detected in 2 of the 5 ceftriaxone-resistant isolates. The prevalence of ceftriaxone resistance, although low, is a concern because it limits therapeutic options. Continued surveillance of ceftriaxone resistance is important to monitor its trends.
Salmonella is an important foodborne pathogen, whose ability to resist stress and survive can vary among strains. This variability is normally not taken into account when predictions are made about survival in foods with negative consequences. Therefore, we examined the contribution of variable phenotypic properties to survival under stress in 10 Salmonella serovars. One strain (Typhimurium 10) was intentionally RpoS-negative; however, another strain (Heidelberg) showed an rpoS mutation, rendering it inactive. We assessed an array of characteristics (motility, biofilm formation, bile resistance, acid resistance, and colony morphology) that show major variability among strains associated with a 10- to 19-fold difference between the highest and the lowest strain for most characteristics. The RpoS status of isolates did not affect variability in the characteristics, with the exception of resistance to NaCl, acetic acid, lactic acid, and the combination of acetic acid and salt, where the variability between the highest and the lowest strain was reduced to 3.1-fold, 1.7-fold, 2-fold, and 1.7-fold, respectively, showing that variability was significant among RpoS-positive strains. Furthermore, we also found a good correlation between acid resistance and lysine decarboxylase activity, showing its importance for acid resistance, and demonstrated a possible role of RpoS in the lysine decarboxylase activity in Salmonella.
Salmonella Typhimurium is an important nontyphoidal Salmonella serovar associated with foodborne diseases in many parts of the world. This organism is the major causative agent of nontyphoidal salmonellosis in Malaysia. We aimed to investigate the genetic profiles of the strains isolated from clinical, zoonotic, and dietary sources in Malaysia using multilocus variable number tandem repeat analysis (MLVA) and pulsed-field gel electrophoresis (PFGE). By focusing on the 5 common variable number tandem repeat (VNTR) loci, we found that PFGE (D = 0.99) was more discriminative than MLVA (D = 0.76). The low MLVA score might be because of a lack of VNTR loci STTR6 (81.0%) and STTR10pl (76.2%). Both subtyping methods suggested that our S. Typhimurium strains were largely endemic with limited genetic variation. Furthermore, we observed that biphasic S. Typhimurium strains were dominant (99%) and multidrug resistance was prevalent (50%) within our sample pool. The most frequently observed phenotypes were resistance to compound sulfonamides (49%), tetracycline (51%), and streptomycin (52%). In this study, we documented the genetic relationship, antimicrobial resistance characteristics, and flagellar-phase dominance among S. Typhimurium strains found in Malaysia.
In recent decades major declines in urban house sparrow (Passer domesticus) populations have been observed in north-western European cities, whereas suburban and rural house sparrow populations have remained relatively stable or are recovering from previous declines. Differential exposure to avian pathogens known to cause epidemics in house sparrows may in part explain this spatial pattern of declines. Here we investigate the potential effect of urbanization on the development of a bacterial pathogen reservoir in free-ranging house sparrows. This was achieved by comparing the prevalence of Salmonella enterica subspecies enterica serotype Typhimurium in 364 apparently healthy house sparrows captured in urban, suburban and rural regions across Flanders, Belgium between September 2013 and March 2014. In addition 12 dead birds, received from bird rescue centers, were necropsied. The apparent absence of Salmonella Typhimurium in fecal samples of healthy birds, and the identification of only one house sparrow seropositive for Salmonella spp., suggests that during the winter of 2013-2014 these birds did not represent any considerable Salmonella Typhimurium reservoir in Belgium and thus may be considered naïve hosts, susceptible to clinical infection. This susceptibility is demonstrated by the isolation of two different Salmonella Typhimurium strains from two of the deceased house sparrows: one DT99, typically associated with disease in pigeons, and one DT195, previously associated with a passerine decline. The apparent absence (prevalence: <1.3%) of a reservoir in healthy house sparrows and the association of infection with clinical disease suggests that the impact of Salmonella Typhimurium on house sparrows is largely driven by the risk of exogenous exposure to pathogenic Salmonella Typhimurium strains. However, no inference could be made on a causal relationship between Salmonella infection and the observed house sparrow population declines.
Salmonella enterica serovar Enteritidis (S. Enteritidis) is the most common causative agent of non-typhoidal salmonellosis in Malaysia. We aimed to characterize S. Enteritidis isolated from humans and animals by analyzing their antimicrobial resistance profiles and genotypes. A total of 111 strains were characterized using multiple-locus variable-number tandem repeat analysis, pulsed-field gel electrophoresis, and antimicrobial susceptibility testing. Both typing methods revealed that genetically similar S. Enteritidis strains had persisted among human and animal populations within the period of study (2003-2008). Only 39% of the strains were multi-drug resistant (i.e., resistant to 3 or more classes of antimicrobial agents), with a majority (73%) of these in low-risk phase (multiple antibiotic resistant index <0.20). Limited genetic diversity among clinical and zoonotic S. Enteritidis suggested that animals are possible sources of human salmonellosis. The degree of multi-drug resistance among the strains was generally low during the study period.
Salmonellosis is one of the major food-borne diseases in many countries. This study was carried out to determine the occurrence of Salmonella spp., Salmonella Enteritidis, and Salmonella Typhimurium in raw chicken meat from wet markets and hypermarkets in Selangor, as well as to determine the antibiotic susceptibility profile of S. Enteritidis and S. Typhimurium. The most probable number (MPN) in combination with multiplex polymerase chain reaction (mPCR) method was used to quantify the Salmonella spp., S. Enteritidis, and S. Typhimurium in the samples. The occurrence of Salmonella spp., S. Enteritidis, and S. Typhimurium in 120 chicken meat samples were 20.80%, 6.70%, and 2.50%, respectively with estimated quantity varying from <3 to 15 MPN/g. The antibiogram testing revealed differential multi-drug resistance among S. Enteritidis and S. Typhimurium isolates. All the isolates were resistance to erythromycin, penicillin, and vancomycin whereas sensitivity was recorded for Amoxicillin/Clavulanic acid, Gentamicin, Tetracycline, and Trimethoprim. Our findings demonstrated that the retail chicken meat could be a source of multiple antimicrobial-resistance Salmonella and may constitute a public health concern in Malaysia.
Food-borne illness caused by Salmonella enterica remains a public health problem and results in economic loss worldwide. With the up-coming establish- ment of the ASEAN Economic Community (AEC) allowing unrestricted move- ment of labor and goods, there is a higher risk of pathogen transmission among the AEC countries. This study characterized and investigated the spatial and temporal associations of S. enterica strains isolated in AEC countries during 1940- 2012 compared with those isolated in northern-Thailand during 2011-2013. Of the 173 S. enterica strains examined, 68 sequence types (STs) and 32 clonal complexes (CCs) were identified by multi loci sequence typing. Twenty-one strains belonged to four sequence types new to AEC countries, and they constituted only two CCs. A number of strains originated from various countries with multiple hosts, were highlighted. There was evidence of strains circulating in the AEC region well over a decade. Such information will be important in formulating biosecurity measures, as well as in educating regarding the risk of disease transmission in AEC.