Resistant Salmonellae Research Articles

Molecular characterization of genes linked to virulence and antimicrobial resistance in salmonella sp. isolated from broiler chickens

Molecular characterization of genes linked to virulence and antimicrobial resistance in salmonella sp. isolated from broiler chickens

Prevalence and antimicrobial resistance of salmonellae isolated from eggs of local chicken in selected towns of Ethiopia.

Salmonellosis is one of the most common food-borne diseases in industrialised and developing countries. In recent year, an increase in antimicrobial resistance among different Salmonella serotypes has been observed. A cross-sectional study was conducted to assess the prevalence and antimicrobial susceptibility of Salmonella isolated from local chicken eggs in four selected towns in Ethiopia. A total of 115 eggs were examined to detect Salmonella by using standard microbiological methods. The susceptibilities of the isolates to nine antimicrobials were tested by the Kirby-Bauer disk diffusion method. The study revealed that of the 115 eggs examined, 22 (19.1%) were positive for Salmonella of which 14 (12.2%) and 8 (7%) of the isolates were from shells and contents, respectively. The occurrence of Salmonella in egg shells and content and between different altitudes did not differ significantly (p > 0.05). Most isolates were resistant to more than three antimicrobials with a high resistance to kanamycin, ampicillin, nalidixic acid, cotrimoxazole, oxytetracycline and chloramphenicol. The results indicate the potential importance of local chicken eggs as source of multiple antimicrobial-resistant salmonellae and the need for proper cooking before consumption. Further studies are required to describe the epidemiology of Salmonella in various agroclimatic zones of Ethiopia.

Ciprofloxacin and Azithromycin Susceptibility in Salmonella Causing Bloodstream Infection in a Tertiary Care Hospital in South India

Enteric fever is a major health concern worldwide, especially in tropical countries. Enteric fever caused by Salmonella enterica is a gastrointestinal tract disease to begin with and later involving many systems,. After the advent of multidrug resistant Salmonellae, ciprofloxacin became the focus of its treatment. Azithromycin is widely being used for the prevention and treatment of Enteric fever. Of late, there are reports in literature to support that Salmonella have regained susceptibility to Ampicillin, Cotrimaxazole and Chloramphenicol. Therefore, this study undertaken aims to find out the antimicrobial susceptibility of Salmonella isolates to conventional drugs like Ampicillin, Cotrimaxazole and Chloramphenicol and find out susceptibility pattern of Ciprofloxacin that is over used for treatment of enteric fever and Azithromycin, most often used in children. As there is no disc diffusion method as per CLSI 2019 guidelines to detect the susceptibility to ciprofloxacin, ciprofloxacin resistance was determined by minimum inhibitory concentration(MIC)by E-test.Kirby-Bauer disk diffusion technique was used to monitor Azithromycin resistance among Salmonella entericaserovarTyphi as per CLSI 2019 guidelines. METHODS:The Prospective study was conducted over a period of 8 months (May 2019- December 2019) with the clinical samples yielding the growth of Salmonella from blood. These strains were screened for Ciprofloxacin susceptibility by E-test. Azithromycin,Ampicillin, Co-Trimaxazole and Chloramphenicol susceptibility were detected by Kirby-Bauer disc diffusion technique. RESULTS: Of the 80 isolates that were screened, 52 (65%) were resistant, 24 (30%) were intermediate susceptible and remaining 4(5%) were sensitive to ciprofloxacin by MIC detection. 69 (86.25%) of the isolates were sensitive and 11 (13.75%) were resistant to Azithromycin by disc diffusion technique. All isolates (100%)were found to be susceptible to Ampicillin, Co-Trimaxazole and Chloramphenicol CONCLUSION:The current study shows a high prevalence of resistance to ciprofloxacin in Salmonella species isolated in and around Mysuru district in southern India. Detection of ciprofloxacin resistance by the Kirby Bauer disk diffusion method is less effective, so it is advised that MIC of ciprofloxacin must be regularly done in the diagnostic laboratories for all strains. The findings from our study also showed low level resistance (13.75%) to Azithromycin. It is advised that Azithromycin can be used as a therapeutic agent only if it is reported to be sensitive by the susceptibility test. Conventional agents like Ampicillin, Co-Trimaxazole and Chloramphenicol can be reconsidered for treatment of Enteric fever.

Plasmid Profile of Environmental and Clinical Isolates of Multidrug Resistant Salmonella Typhimurium from Patients Attending General Hospital Asokoro, Abuja and Environ

Plasmid is isolated from Salmonella typhimurium, an enteric bacterium responsible for gastro enteritis. Gastro enteritis remains a major clinical and public health problem all over the world, especially among children in the developing countries of the sub – Sahara Africa. The profiling of plasmid isolate of Salmonella typhimurium involved cultivation, isolation, identification, and characterization. The study aimed at investigating the multidrug resistance of salmonella typhimurium of patients attending General Hospital Asokoro with typhoid fever and the susceptibility of isolates to antibiotics. A total of thirty (30) samples, from blood, stool, and water were collected from patients attending General hospital, Asokoro and the environs. The specimens were analyzed using standard microbiological, biochemical, and serological techniques. Bacteriological analysis revealed that twenty-five (25) of the specimens were positive for Salmonella typhimurium. The other five (5) specimens were negative for salmonella typhymurium typhimurium. The biochemical test revealed that they were able to utilize sugar and are lactose fermenter. Anti-microbial susceptibility determination revealed that the most active drugs against salmonella include Ciprofloxacin, Ofloxacin, Amikacin, and Gentamicin. All the isolates were resistant to tetracycline and Ampicillin. There was marked resistance of all isolates to amoxicillin, doxycycline, and chloramphenicol. The result of findings revealed that the genes that encode resistance properties in Salmonella typhimurium are plasmid- borne in some of the bacteria. These plasmids can be cloned and used for genetic engineering and recombinant DNA technology. The antibiotic susceptibility determined the appropriate drugs efficient for therapy of Salmonella infections. Keywords: Antibiotic Susceptibility, Drug Resistance, Salmonella typhimurium, Plasmid.

Drug Resistance Mechanism and Detection Method of Salmonella

As an important zoonotic food-borne pathogen, Salmonella is a concern for public health authorities. In particular, bacteria that are resistant to multiple antimicrobials can confuse the efficacy of treatment for infectious diseases. Drug-resistant bacteria have a variety of drug-resistant molecular and cellular mechanisms. These antimicrobial resistance mechanisms include antibiotic efflux, permeability changes in cell membranes, enzymatic drug inactivation, biofilm formation, drug target changes, and protection of antimicrobial targets. In this paper, the mechanisms of antimicrobial resistance in salmonella and the techniques of detecting antibiotic resistance by traditional and molecular methods are reviewed, with emphasis on their advantages and disadvantages, as well as the validity and reliability of the results.

Current Sensitivity Pattern of Salmonella Species in Children Presenting at a Tertiary Care Hospital

Background: Enteric fever is a common and treatable pediatric bacterial infection, but emerging drug resistance has been a real challenge for treating physicians. Since 2016, Pakistan is facing the epidemic of Extensively drug resistant (XDR) salmonella typhi. Objective: To determine the clinical presentation and current pattern of sensitivity of salmonella species in children diagnosed with enteric fever. Study Design: Descriptive, Cross sectional Place and Duration of Study: Pediatric department of Dr. Ruth K. M. Pfau Civil Hospital Karachi, from July to December 2022. Methods: Medical records of patients 1 month to 12 years of age, diagnosed as enteric fever on positive blood culture for salmonella, were inducted into the study by non-probability convenient sampling. The clinical manifestations of patients and sensitivity and resistance patterns of salmonella were recorded. Data was analyzed using SPSS version 22. Results: A total of 140 children had enteric fever, out of which 60.7% were male. Mean age of the patients was 4.48+2.47 years. Most common symptom was fever in 140 (100%), followed by anorexia in 97 (69.2%) and abdominal pain in 70 (50%). Blood culture reports showed Extensive drug resistance in 105 (75%), Multi drug resistance in 3 (2.14%) and Non-resistance in 7 (5%). Salmonella Typhi isolates were sensitive to Carbapenems in 140 (100%), Azithromycin 139 (99.2%) and Piperacillin/Tazobactam in 60 (42.8%). Conclusion: XDR enteric fever is still the most common resistance pattern identified in admitted patients with enteric fever. Large scale public health measures and antibiotic stewardship are required to fight this disease. Keywords: Typhoid fever, Salmonella Typhi, Drug resistance, Infection, Epidemic

Genotypic and phenotypic characterization of a Salmonella Typhimurium strain resistant to pulsed electric fields

Pulsed Electric Fields (PEF) technology is regarded as one of the most interesting alternatives to current food preservation methods, due to its capability to inactivate vegetative microorganisms while leaving the product's organoleptic and nutritional properties mostly unchanged. However, many aspects regarding the mechanisms of bacterial inactivation by PEF are still not fully understood. The aim of this study was to obtain further insight into the mechanisms responsible for the increased resistance to PEF of a Salmonella Typhimurium SL1344 variant (SL1344-RS, Sagarzazu et al., 2013), and to quantify the impact that the acquisition of PEF resistance has on other aspects of S. enterica physiology, such as growth fitness, biofilm formation ability, virulence and antibiotic resistance. WGS, RNAseq and qRT-PCR assays indicated that the increased PEF resistance of the SL1344-RS variant is due to a higher RpoS activity caused by a mutation in the hnr gene. This increased RpoS activity also results in higher resistance to multiple stresses (acidic, osmotic, oxidative, ethanol and UV-C, but not to heat and HHP), decreased growth rate in M9-Gluconate (but not in TSB-YE or LB-DPY), increased ability to adhere to Caco-2 cells (but no significant change in invasiveness) and enhanced antibiotic resistance (to six out of eight agents). This study significantly contributes to the understanding of the mechanisms of the development of stress resistance in Salmonellae and underscores the crucial role played by RpoS in this process. Further studies are needed to determine whether this PEF-resistant variant would represent a higher, equal or lower associated hazard than the parental strain.

ЭТИОЛОГИЧЕСКАЯ СТРУКТУРА САЛЬМОНЕЛЛЕЗА И ЧУВСТВИТЕЛЬНОСТЬ МИКРООРГАНИЗМОВ К АНТИБАКТЕРИАЛЬНЫМ ПРЕПАРАТАМ

Salmonellosis is one of the most common acute intestinal diseases, often occurring in the form of group outbreaks with food transmission factor. Among infections of bacterial etiology, it has the highest incidence rates. Infection is registered in all countries and is an pressing medical problem, including the Russian Federation. Also, the public health problem is the resistance of the pathogen to antimicrobial drugs, there is a constant need to determine sensitivity for the correction of therapy. The purpose of our study was to determine the etiological structure of salmonellosis and sensitivity of individual salmonella isolates to antibacterial drugs in the Republic of Mordovia in various years of observation. The material of this study was the case histories of 500 patients hospitalized in Republican Infectious Diseases Clinical Hospital. For this purpose, a retrospective analysis of medical records was carried out. We have identified that in the territory of the Republic of Mordovia, the incidence of salmonellosis for many years exceeded the average incidence in Russia. At the same time, its decline was noted during the pandemic of the new coronavirus infection (as well as in Russia as a whole). The article reflects the results of the analysis of the etiological structure, provides data on the dynamic monitoring of the sensitivity of salmonella to antibacterial drugs in the republic. We noted that the appearance of new serological variants of the pathogen is often recorded. At the same time, S. Enteritidis remains predominant. Enteritidis, Munchen, Newport, and Glostrup were highly sensitive to fluoroquinolones, betalactams, cephalosporins, carbapenems, and monobactams. However, there is a growing trend in the resistance of salmonella to antibacterial drugs, sometimes simultaneously to five and six. Low sensitivity was revealed to ampicillin, gentamicin, tetracycline (more often in S. Enteritidis and S. Glostrup). The information obtained can be used to assess the epidemiological situation, to monitor antimicrobial resistance within the framework of epidemiological surveillance, to optimize antibacterial therapy, as well as in the educational process and clinical practice.

Evaluation of antibiotic resistance in salmonella isolated from camel in a Najaf province

Non-Typhoidal Salmonellosis (NTS) is a form of salmonellosis that infect human from host-non adapted serotypes of salmonella, these salmonella strains are distributed in the environment, water and food via warm blooded animals causing gastroenteritis illnesses mostly, accompanied by high antibiotic resistance profile. In Najaf, camel meat considered one of the most used meat for human consumption. Yet, studies on distribution of salmonella and antibiotic resistance is scarce. In this research, (32) isolates of salmonella were isolated from camels in the province of Al-Najaf, using ordinary bacteriological methods, according to internationally known protocols for the cultivation and characterization of this bacteria. Then, all positive isolates subjected by antibiotic sensitivity test. The results showed a very high multidrug resistance profile was noticed among the isolated salmonella.

Occurrence of Multi-drug Resistant Avian Salmonellae in Commercial Poultry

Background: Salmonellosis is of great concern among the infectious diseases of poultry and has been responsible for serious economic losses to the poultry producers and a shift in Salmonella serotypes has been evident in recent years. Study was carried out to know the occurrence and pathology of Salmonellae infection in poultry along with their multi-drug resistance. Methods: Samples for study were collected from 26 organized poultry farms. To determine the presence of Salmonella in the farms, microbial culture from fecal swabs and pooled fecal samples was carried out for isolation of bacteria. Molecular detection of Salmonella isolates was also performed using direct PCR. Biofilm producing ability of the bacteria was also assessed and antibiotic sensitivity test was done to detect the resistance of bacterial isolates. Result: Salmonellosis in broiler and layer farms was recorded as 20% and 45.4% respectively and in 1.58% of the necropsy cases through microbial culture. Molecular detection of Salmonella isolates by PCR targeting invA gene was confirmed in 13.33% broiler farms and 36.3%-layer farms. Further detection of Salmonella Enteritidis was performed by PCR targeting ent gene and 11.11% positivity was determined. Biofilm producing ability of the bacteria was found 40% using biofilm assay. Serological examination using polyvalent antisera diagnosed 27.27% isolates as motile salmonellae. During necropsy of positive cases gross lesions comparable to salmonellosis were noted in liver, intestine, spleen and ovary. Multi-drug resistant (MDR) pattern was observed with highest resistance towards oxytetracycline, streptomycin followed by amikacin, amoxicillin and enrofloxacin. The presence of multiple drug resistant Salmonella in chicken has rendered the food chain unsafe from farm to table and hence continuous surveillance of the disease should be encouraged.

Association of extensively drug resistant salmonella infection in children with typhoid fever.

Objectives:In resource limited countries facing a huge burden of multidrug resistant and extensively drug resistant (XDR) enteric fever, treatment is a great challenge on the part of a patient as well as a health care professional. This study was conducted to determine the association of XDR enteric fever with various studied factors among hospitalized culture-positive pediatric patients in a tertiary care hospital setup.Methods:We conducted a descriptive observational study at The Karachi Adventist Hospital from July 01, 2019, to March 31, 2020 on 143 hospitalized children with culture proven enteric fever who were already on empirical antibiotics. Depending on the variability of the course of illness and clinical responses to given antibiotics, the data was gathered on a structured data sheet. Association of various study parameters and their significance in relation to XDR salmonella infection was analyzed and studied.Results:The age group highly affected was 5-7.5 years, with a male preponderance of 61.5%. Majority were from urban slums areas of Karachi (53.8%) and 52% were admitted between 7 to 14 days of fever onset. XDR salmonella infection was observed in 79% of blood culture isolates. None of the XDR patients were consuming boiled water and neither of these infected children were vaccinated against salmonella typhi. Duration of fever before hospitalization, non-consumption of boiled or mineral water, ciprofloxacin use and lack of typhoid vaccination showed statistically strong association with XDR enteric fever (p<0.01).Conclusion:Prehospitalization fever duration, use of boiled/mineral water, ciprofloxacin use and typhoid vaccine status showed strong association with XDR salmonella infection. Prioritizing the focus on healthcare awareness, early access to proper health care facility, discouraging over-the-counter drugs and enforcement of immunization will help decline the dissemination of this dreadful disease.

Prevalence and antimicrobial susceptibility level of typhoid fever in Ethiopia: A systematic review and meta-analysis

Typhoid fever continues to be a health challenge in low-and middle-income countries where access to clean water and sanitation infrastructure is scarce. The non-confirmatory diagnostic method continues to hinder effective diagnosis and treatment, ensuring in a high antimicrobial resistance. This systematic review and meta-analysis aimed to estimate the pooled prevalence and antimicrobial susceptibility level of typhoid fever in Ethiopia.The review was designed based on the condition-context-population review approach. Fifteen eligible articles were identified from PubMed, Google Scholar, and Science Direct databases. Risk of bias and quality of studies were assessed using the Joanna Briggs Institute’s appraisal criteria. Heterogeneity was assessed using Cochran’s Q test and I2 statistics. The review protocol was registered in PROSPERO (registration number CRD42021224478).The estimated pooled prevalence of typhoid fever from blood and stool culture diagnosis was 3% (95% CI: 2%–4%, p < 0.01) (I2 = 82.25) and Widal test examination 33% (95% CI: 22%–44%) (I2 = 99.14). The sub-group analyses identified a lower detection of typhoid fever of 2% (95% CI: 1%–3%) among febrile patients compared to typhoid suspected cases of 6% (95% CI: 2%–9%). The stool culture test identified was twofold higher, value of 4% (95% CI: 2%-7%) salmonella S. Typhi infection than blood culture test of 2% (95% CI: 1%–4%). The antimicrobial susceptibility of salmonella S. Typhi for antibiotics was 94%, 80% and 65% for ceftriaxone, ciprofloxacin, and gentamycin respectively. Low susceptibility of salmonella S. Typhi isolates against nalidixic acid 22% (95% CI: 2%–46%) and chloramphenicol 11% (95% CI: 2%–20%) were observed. The diagnosis of typhoid fever was under or overestimated depending on the diagnostic modality. The Widal test which identified as nonreliable has long been used in Ethiopia for the diagnosis of salmonella S. Typhi causing high diagnosis uncertainties. Antimicrobial susceptibility of salmonella S. Typhi was low for most nationally recommended antibiotics. Ethiopian Food and Drug Authority must strengthen its continued monitoring and enhanced national antimicrobial surveillance system using the best available state-of-the-art technology and or tools to inform the rising resistance of salmonella S. Typhi towards the prescription of standard antibiotics. Finally, it is crucial to develop an evidence-based clinical decision-making support system for the diagnosis, empiric treatment and prevention of antimicrobial resistance.

A case of Extensively Drug Resistant (XDR) Extended Spectrum Beta-Lactamase (ESBL) typhoid fever in the Ambulatory Emergency Care (AEC) unit

An outbreak of Extensively Drug Resistant (XDR) Salmonella Typhi (S. Typhi) has recently emerged from Pakistan. The strain is resistant to most first-line antibiotics, including cephalosporins, and has become a significant public health threat due to limited treatment options. We report one such case of S. Typhi in a 48-year-old female presenting to our West London ambulatory emergency care department. The patient, who had recently travelled to Pakistan, presented with symptoms of a dry cough, fever, maculopapular rash, and dysuria. Blood cultures initially isolated Salmonella spp, serotype Typhi and empirical ceftriaxone was commenced. Antibiotic sensitivity testing (AST) identified Salmonella spp. ESBL (Extended Spectrum Beta Lactamase-producing) subspecies I (ST1 EBG:13), with cephalosporin and fluoroquinolone resistance (ciprofloxacin MIC 2 mg/L), hence labelling it XDR. It retained susceptibility to meropenem and azithromycin (azithromycin MIC 12 mg/L). An ESBL Escherichia coli was concurrently grown in urine cultures. Once antibiotic sensitivities were available, the patient was converted from ceftriaxone to a course of azithromycin orally and ertapenem intravenously. The patient defervesced promptly, demonstrated blood and urine clearance on follow up and was successful treated. This case report highlights the limitations of ceftriaxone in our empirical management of suspected typhoid fever, especially in those returning from high-risk regions. Increased prevalence of these resistant salmonella will lead to failures of the current treatment practices and continuous surveillance and improving infection control measures are required to mitigate the spread of these XDR S. Typhi. Azithromycin and carbapenems retain in vitro activity and play an important role in treatment of XDR S. Typhi; loss of the organism’s sensitivity to these agents presents a serious public health threat. Further studies are warranted to confirm in vivo efficacy of ertapenem particularly when used as monotherapy.

Clinical profile and antibiotic sensitivity pattern of typhoid fever in children: a hospital based prospective study from a tertiary care center

Background: Typhoid fever is a serious public-health problem in many developing countries including India. There is a wide spectrum of clinical presentation and with the emergence of multidrug resistant typhoid now a days, the treatment has become still more complex. The present study authors describe the clinical profile and antibiotic sensitivity pattern of typhoid fever in children from a tertiary care in Mahabubnagar, Telangana, South India.Methods: This hospital based prospective observational study was done in Department of Pediatrics, SVS Medical College, Mahabubnagar, Telangana over a period of 3-year period from January 2017 to December 2019. The study was approved by institutional ethics committee. Written informed consent was obtained from children’s parents. All pediatric patients diagnosed as typhoid fever if presented with fever (temperature &gt;38ºC) for at least 3 days with positive blood culture for S. typhi or paratyphi were included in the study. The demographic profile and clinical data were recorded and tests including antibiotic sensitivity and resistance were done.Results: A total of 136 patients were included in the study. Majority of the children were between 8 to 12-year age group (38.2%). Out of 136 children, 78 were males and 58 were females. Majority of the cases were from rural areas accounting for 69%. Drinking water source was tap water in 63% cases and bore well water in 37% cases. Majority (65%) belonged to lower socioeconomic class and 68% were during rainy seasons. The clinical findings observed were fever (100%), vomiting (98, 72%), diarrhea (55.8%), headache (45.5%), and splenomegaly (42.6%). Other clinical features found were coated tongue, abdominal pain, hepatomegaly, constipation, and dehydration. Six children had complications, 3 had enteric hepatitis, 2 had shock, and 1 had encephalopathy. Ampicillin, amoxicillin and chloramphenicol resistance was observed in 76%, 71% and 22% of patients with typhoid fever respectively. Maximum sensitivity was observed with ceftriaxone (95%), followed by aztreonam (92%), ciprofloxacin (84.5%), and azithromycin (77%).Conclusions: Clinical presentation in the study subjects was similar to available reports from literature. Increasing resistance of salmonella to Ampicillin and amoxicillin were observed.

Prevalence of Multidrug Resistant Salmonellae with Increasing Frequency of &lt;i&gt;Salmonella enterica&lt;/i&gt; Serovars Kentucky and Virchow among Hospitalized Diarrheal Cases in and around Delhi, India

Non-typhoidal salmonellae (NTS) are a major cause of acute diarrhea with characteristic multidrug resistance (MDR). In a hospital-based study, 81 NTS were isolated and tested for serotypes and antimicrobial resistance (AMR). Salmonella enterica isolates were classified into 7 different typable serovars, however, 19 (23%) isolates remained untypable. The most common serovars were S. Kentucky (48%), and S. Virchow (22%). Most of the NTS isolates displayed resistance to nalidixic acid (NA) (73%), ciprofloxacin (CIP) (48%), ampicillin (AM) and norfloxacin (NOR) (36% each), and gentamicin (CN) (31%). The AMR profiles for CN and NA; and AM, CIP, NA and NOR, were found to be high in S. Virchow (83%) and S. Kentucky (43%), respectively. Analysis of the pulsed-field gel electrophoresis patterns of S. Kentucky revealed 3 clusters. S. Kentucky has clones closely related to become prominent in recent years in Delhi. The AMR appears to be consistent with the change in MDR patterns during 2014-2017. The observed prevalence of S. Kentucky and S. Virchow in large numbers of diarrheal cases is novel. The NTS are mostly resistant to fluoroquinolones, which is the current drug of choice for treating diarrheal cases. MDR is very common among clonally related S. Kentucky.

Prevalence and antimicrobial resistance of &lt;em&gt;Salmonella&lt;/em&gt; and &lt;em&gt;Yersinia&lt;/em&gt; in the feces of hunted wildlife in Abeokuta, Nigeria

Meat from wildlife contributes significantly to food security and income generation in many African communities. Salmonellae and yersiniae are important causes of foodborne infections. This study investigated the presence and antimicrobial resistance of salmonellae and yersiniae in the fecal contents of hunted wild rodents and ruminants at a wildlife meat-processing center in Abeokuta, Nigeria. Bacteria were isolated and identified by selective culture methods and biochemical characterization. Antimicrobial susceptibility was determined by the Kirby Bauer disk diffusion method. Salmonellae were isolated from 15 (9.8%) and yersiniae from 11 (7.2%) samples out of 153. Salmonellae were detected in nine cane rats (Thryonomys swinderianus), five royal antelopes (Neotragus pygmaeus) and one African giant rat (Cricetomys gambianus). Yersiniae were detected in eight cane rats, two royal antelopes and one waterbuck (Kobus ellipsiprymnus). The levels of resistance in Salmonella isolates were 100% for ampicillin and ceftiofur, 93.3% for tetracycline, 33.3% for cefotaxime, 26.7% for ceftazidime, 13.3% for amoxicillin/clavulanic acid, nalidixic acid and sulfamethoxazole/trimethoprim, and 6.7% for gentamicin, streptomycin and norfloxacin. The levels of resistance in yersiniae isolates were 81.8% for ampicillin, 72.7% for ceftiofur, 63.6% for nalidixic acid, 54.5% for cefotaxime, ceftazidime and sulfamethoxazole/trimethoprim, 36.4% for tetracycline, 27.3% for amoxicillin/clavulanic acid and streptomycin, 18.2% for ciprofloxacin, and 9.1% for chloramphenicol and gentamicin. All the isolates showed multiresistance to antimicrobials from at least three different classes. The detection of antimicrobial resistant salmonellae and yersiniae in wildlife is of veterinary and public health significance as these organisms can be transmitted to domestic animals and humans.

Generic Salmonella in Asymptomatic Adult Volunteers: Occurrence, Antibiogram, Extended-Spectrum β-Lactamase Production and Carbapenem Resistance

This study was conducted to isolate generic Salmonella from stool of apparently-healthy/asymptomatic adult volunteers in Ankpa North-central Nigeria, and to determine antibacterial susceptibility, extended-spectrum β-lactamase production and carbapenem resistance. About a gram of stool was collected from 295 randomly-selected apparently-healthy/asymptomatic adult volunteers in Ankpa Kogi State, North-central Nigeria. Isolation of Salmonella was done by pre-enrichment with buffered peptone water, enrichment with Rapapport-Vassiliadis and sub-culturing on Salmonella-Shigella and MacConkey agar. Identification of the isolates to genus level was done using standard biochemical tests. Resistance of the isolates was determined by disc diffusion method. Production of ESBL was assessed by combination disc method while carbapenem resistance was determined using meropenem disc screening method. Nine (3.1%) out of 295 samples, gave positive growth of Salmonella. Of these 9 isolates, all were carbapenem (meropenem)-resistant and 1 (11.1%) was ESBL-producer. Among the isolates, all were resistant to ciprofloxacin, ofloxacin, norfloxacin, ampicillin, cefotaxime, ceftazidime, gentamicin and streptomycin, 5 (55.6%) to sulphamethoxazole-trimethoprim, 7 (77.8%) to amoxicillin-clavulanic acid and aztreonam, 6 (66.7%) to nitrofurantoin and 8 (88.9%) to tetracycline. All the isolates were resistant to ≥ 5 classes of antibacterial agents. Mean multiple antibacterial indexes of the isolates were 0.68 (range 0.79 - 1.00). Apparently-healthy/asymptomatic adults in Ankpa North-central Nigeria, are potential reservoirs and disseminators of multi- and extensive-drug resistant salmonellae.

A rare case of Colistin-resistant Salmonella Enteritidis meningitis in an HIV-seropositive patient

BackgroundNon-typhoidal salmonellae (NTS) have been associated with invasive disease, notably meningitis, in immunocompromised individuals. Infections of this nature carry high rates of morbidity and mortality. Colistin resistance in salmonellae is a rare finding, more so in an invasive isolate such as cerebrospinal fluid (CSF). Colistin resistance has important infection control implications and failure to manage this phenomenon may lead to the loss of our last line of defence against multi-drug resistant Gram-negative organisms. To our knowledge, this is the first reported clinical case of colistin-resistant Salmonella Enteritidis meningitis in South Africa.Case presentationWe report a case of a young male patient with advanced human immunodeficiency virus (HIV) infection who presented to hospital with symptoms of meningitis. Cerebrospinal fluid (CSF) cultured a Salmonella Enteritidis strain. Antimicrobial susceptibility testing (AST) of the isolate, revealed the strain to be colistin resistant. Despite early and aggressive antimicrobial therapy, the patient succumbed to the illness after a short stay in hospital. Subsequent genomic analysis of the isolate showed no presence of the mcr genes or resistance-conferring mutations in phoPQ, pmrAB, pmrHFIJKLME/arnBCADTEF, mgrB, and acrAB genes, suggesting the presence of a novel colistin resistance mechanism.ConclusionInvasive non-typhoidal salmonellae infection should be suspected in patients with advanced immunosuppression who present with clinical features of meningitis. Despite early and appropriate empiric therapy, these infections are commonly associated with adverse outcomes to the patient. Combination therapy with two active anti-Salmonella agents may be a consideration in the future to overcome the high mortality associated with NTS meningitis. Colistin resistance in clinical Salmonella isolates, although a rare finding at present, has significant public health and infection control implications. The causative mechanism of resistance should be sought in all cases.

IDENTIFICATION OF VIRULENCE GENES, β-LACTAMS AND QUINOLONES RESISTANCE-ASSOCIATED GENES AND INTEGRONS IN SALMONELLA ISOLATED FROM RETAIL CHICKEN MEAT AND GIBLETS IN EGYPT

The study investigated the prevalence of virulent and antibiotic resistant Salmonella (S) in retail chicken meat (CM) and pooled giblets (PG) in Egypt. Seventy-two and 64 % of examined CM and PG samples harbored Salmonellae, respectively. When S. Infantis was the most predominant serovar, followed by S. Kentucky, and then S. Virchow. The antibiotic resistance experiment showed a high rate of multiple drug resistant (MDR) Salmonellae. Remarkably, 64.7% of the isolates were resistant to ciprofloxacin (the drug of choice for Salmonella infection). Molecularly, a noteworthy correlation between the MDR and the presence of integrons class 1 and 3. When, integrons 1 and 3 were detected in 100 and 92 % of identified MDR isolates, respectively, while class 2 integrons were not found. Surprisingly, 53.8 and 100% of the molecularly identified isolates were resistant to ciprofloxacin and nalidixic acid, despite the absence of plasmid-mediated quinolone resistance (PMQR)-associated genes (qnrA, qnrB and qnrS, aac(6′)-Ib-cr and qepA) from all MDR isolates. This indicates that other genetic factors could be incriminated in this pattern. Beta-lactam resistance was explored by the existence of blaTEM, blaCTX, and blaCMY-2 genes in most MDR isolates. Additionally, 4 virulence genes were detected in almost all serovars. Concerning virulence genes, invA, hilA, sopB, and stn were detected in 100, 100, 100 and 94.7 % of MDR serovars, respectively. While, spvC was detected in only 7.6 %, and pef was absent. The high prevalence of MDR virulent Salmonella strains in retail chicken meat and giblets in Egypt should be faced with a great worry, as consumers could be under a great public health risk.

Drug of Choice in the Treatment of Multiple Drug Resistant (MDR) Salmonellae Isolated from Wildlife in Nigeria

Multiple drug resistant (MDR) strains of Salmonella are frequently encountered with increased rates in recent years. Many variants of the organism have developed MDR genes which they retain even when antimicrobial drugs are no more in use, limiting the choice of drugs for therapy of Salmonella infections resulting in morbidity and mortality in both man and animals and raising more public health questions. The objective of this study was to evaluate the susceptibility of Salmonella spp. to twelve antimicrobial agents using the disk diffusion method. Eight Salmonella spp. isolated from wildlife were tested. All the isolates exhibited MDR, showing resistance to at least four and up to nine antimicrobial agents. They were all highly resistant (100%) to ceftazidime, cephazoline, cefuroxidine and ampicillin but were susceptible to nalidixic acid and ciprofloxacin. Six resistant patterns were observed, with ampicillin-cefuroxime sodiumcephazolin-ceftazidime and streptomycin-ampicillin-cefuroxime sodium-cephazolin-ceftazidime resistant patterns exhibited by two isolates each. The substantial multiple resistance pointed to the fact that limitations could be faced in choosing drugs for the treatment of Salmonella infections and that mortality and economic losses could be experienced especially if sensitivity tests are not carried out before antimicrobial choice is made for treatments in both man and animals.