Revisiting the Revised CLSI Breakpoint for Detecting Fluoroquinolones Resistance in Salmonella

Resistance towards fluoroquinolones and treatment failure is a matter of concern in enteric fever. The present study was undertaken to analyze the susceptibility pattern of Salmonella towards fluoroquinolones using 2006 and 2013 Clinical Laboratory Standards Institute (CLSI) breakpoint for interpretation and revisit the efficacy of Nalidixic acid resistance (NAR) as a phenotypic marker. A retrospective analysis of the zone of inhibition (ZOI) diameter data and minimum inhibitory concentration (MIC) data of 105 Salmonella was conducted. The ZOI diameter analysis showed that all isolates were susceptible to Ofloxacin and Ciprofloxacin using the previous 2006 ZOI breakpoint. However, with the revised 2013 breakpoint of Ciprofloxacin, the susceptibility percent dropped significantly and for Ofloxacin the breakpoint was not revised, so the percentage remained unchanged. The MIC analysis showed that all isolates were susceptible towards Ofloxacin and 97.14 % of isolates were susceptible to Ciprofloxacin using the previous 2006 MIC breakpoint, while the susceptibility decreased for both antibiotics with the revised 2013 MIC breakpoint. Statistically, the ZOI diameter of Nalidixic acid and MIC values of Ciprofloxacin and Ofloxacin was negatively correlated. To conclude, the revision of breakpoints addresses the problem of screening fluoroquinolones resistance but the emerging fluoroquinolones resistance situation is still a matter of concern in healthcare facilities of Nepal. Thus a reliable screening method is need of the hour as NAR cannot be considered a reliable marker to screen fluoroquinolones resistance

Antimicrobial resistance Salmonella isolates recovered from food products of animal origin in the Russian Federation

The study was aimed at Salmonella isolation from samples of animal food products submitted for testing from various regions of the Central part of the RF and serotyping of the recovered isolates and their testing for antibiotic resistance. A total of 2,342 tests were performed and 87 (3.7%) Salmonella isolates were recovered. Most of them (54 isolates) were recovered from poultry meat and poultry meat preparation samples submitted for testing. Besides, 25 isolates were recovered from pork and pork preparation samples, 7 isolates – from beef samples, 1 isolate – from hard cheese samples. Serotyping of 64 Salmonella isolates showed that the majority of the isolates (57.8%) belonged to О7 group. Also, Salmonella isolates belonging to О9 (21.9%), О8 (9.4%), О4,5 (6.2%) and О10 (4.7%) were detected in food products. S. Enteritidis, (23.3%), and S. infantis (18.7%), were predominant based on the number of detections. Also, the following serovars were identified: S. typhimurium, S. nigeria, S. montevideo, S. derby, S. meleagridis, S. virchov, S. oranienburg. Tests of 87 Salmonella isolates for their antibiotic resistance with disk diffusion method revealed that they were highly resistant to nalidixic acid (70.1%), tetracycline (49.4%), trimethoprim/sulfamethoxazol (40.2%). Moreover, nalidixic acid-resistance was common for all identified isolates. Seventeen isolates (19.5%) demonstrated multiple antibiotic resistance and two isolates were found to be resistant to ≥7 antibiotics. All recovered isolates were susceptible to gentamicin, amikacin, meropenem and imipenem. Obtained results indicate the necessity of Salmonella antibiotic resistance monitoring to gain understanding of Salmonellas’ antibiotic resistance emergence and trends.

Phenotypic and genotypic examination of antimicrobial resistance in thermophilic Campylobacter species isolated from poultry in Turkey

Introduction:The study aimed to isolate thermophilicCampylobacterfrom chickens raised three rearing methods, determine its antimicrobial susceptibilities, and examine resistance-related genes by PCR.Material and Methods:Cloacal swabs or intestinal contents were taken in Istanbul, Sakarya, and Izmir provinces. Chickens were from small village-based family-run businesses (n = 70), organically raised (n = 71), and conventionally raised broilers (n = 79). The samples were cultured on modified charcoal cefoperazone desoxycholate (mCCD) agar. Suspect isolates were identified with multiplex PCR (mPCR). As per EUCAST standards, MIC values were derived by broth microdilution for tetracycline, ciprofloxacin, nalidixic acid, kanamycin, gentamicin, and erythromycin in isolates ofC. jejuni(n = 98) andC. coli(n = 83).Results:InC. jejuni, 78.6% tetracycline, 87.8% ciprofloxacin, and 81.6% nalidixic acid resistance was detected, but none was to kanamycin, gentamicin, or erythromycin. InC. coli, 98.8% ciprofloxacin and 63.9% nalidixic acid resistance was detected, whereas resistance to nonquinolones was not observed. C257T (Thr-86-Ile) mutation in thegyrAgene of all phenotypically quinolone-resistant isolates was detected through a mismatch amplification mutation assay PCR (MAMA-PCR). It emerged that all isolates bore thetet(O) resistance gene.Conclusion:Common tetracycline, nalidixic acid, and ciprofloxacin resistance exists inCampylobacterisolated from chickens raised three rearing methods.

Antibiogram of Salmonella Spp Isolates in Kathmandu, Nepal

INTRODUCTION: Drug resistant Salmonella spp. is endemic in several Asian countries. Nalidixic acid-resistant Salmonella enterica serovar Typhi and Salmonella enterica serovar Paratyphi A show reduced susceptibility to fluoroquinolones and have resulted in a rise in treatment failures. Over the past few decades, nalidixic acid-resistant Salmonella spp have emerged in Nepal as well.MATERIAL & METHODS: This is a retrospective study that aims to provide a more recent antibiogram of S. Typhi and S. Paratyphi A isolates in Kathmandu. Between Poush, 2071 and Ashwin, 2072 (December 16, 2014 to October 17, 2015), 186 culture positive cases of enteric fever were diagnosed at the Civil Service Hospital. Upon isolation of S. Typhi or S. Paratyphi A, antimicrobial susceptibility testing was performed with amoxicillin, azithromycin, ceftriaxone, chloramphenicol, ciprofloxacin, cotrimoxazole, nalidixic acid, ofloxacin and tetracyciline.RESULTS: This study shows a much higher frequency of nalidixic acid-resistance in Kathmandu than previously reported; 95.7% in Salmonella enterica serovar Paratyphi A and 86.5% in Salmonella enterica serovar Typhi.The rates of ciprofloxacinand ofloxacin-resistance were over 50% in both serovar.CONCLUSION: In Nepal, it is necessary to reevaluate the use of fluoroquinolone therapy and introduce feasible alternatives so as to curb treatment failures.Journal of Universal College of Medical Sciences (2017) Vol. 5, No, 2, Page: 22-25

Adaptation of Esherichia coli to Antiobiotic Cycling via Single Nucleotide Polymorphisms

Bacteria are quick to adapt and evolve, especially under the effects of selective pressures from chemical antibiotics. In addition, bacteria may develop resistance to antibiotics from multiple classes simultaneously, making their eradication from the human body particularly challenging. This study aims to demonstrate that bacterial multiple-drug resistance can be developed and retained in a laboratory setting. Escherichia coli B was grown in tryptic soy broth in the presence of a small, increasing concentration of streptomycin. This exposure resulted in a strain of E. coli, which had an increased minimum inhibitory concentration (MIC) towards streptomycin, or “resistance.” This resistant strain was then grown in like manner in nalidixic acid and then penicillin G. The result was a strain that became resistant to streptomycin and nalidixic acid, and increasingly resistant to nalidixic acid after penicillin G exposure. Additionally, the bacteria retained resistance to streptomycin and nalidixic acid even after exposure to those chemicals ceased. Genome sequencing and comparison to E. coli B reference strain REL606 revealed the emergence of point mutations with each exposure to an antibiotic. Of particular interest is a mutation associated with the appearance of nalidixic acid resistance. Base pair 4,553,488 was changed from adenine to guanine, resulting in a change from aspartate to glycine in the protein helicase. Previous studies have not indicated mutations to this locus as nalidixic acid resistance conferring. Thus, this mutation may be a novel mutation conferring E. coli B nalidixic acid resistance. Since the region of the mutated helicase is functionally undefined, a mechanism is not apparent. Further research needs to be done to confirm this hypothesis and illuminate a mechanism. KEYWORDS: Bacteria; Escherichia coli; Evolution; Antibiotic Resistance; Nalidixic Acid; Streptomycin; Point Mutation; Single-nucleotide Polymorphism; Helicase; Minimum Inhibitory Concentration

Prevalence and antimicrobial resistance of Campylobacter isolates from poultry offals

The aim of the study was to determine the presence of Campylobacter strains in poultry by-products and define antimicrobial resistance of isolates. In total, 400 samples were tested among which 300 included the liver, heart and stomach, and 100 samples represented the contents of the cecum. The samples were taken from chickens and turkeys in the slaughterhouse after evisceration. The prevalence of Campylobacter in chicken samples was 100% with regards to the contents of cecum and offal. The turkey origin Campylobacter strains were noted in 76% of the livers, 78% hearts and 82% gizzards. The samples of cecum contents were positive in 60%. Species analysis of the strains isolated showed C. jejuni as dominant. The estimation of sensitivity to antibiotics showed that Campylobacter strains were most frequently resistant to quinolones and tetracyclines. Resistance to ciprofloxacin was detected among 52.7% and 52.5% chicken and turkey origin strains. The same was noted regarding nalidixic acid, resistance to which was shown in 56% and 58.5% isolates, respectively. Regarding tetracyclines, the highest resistance of the strains from chicken and turkey was detected to doxycyclinum in 61.3% and 53.3% of isolates, respectively. However the highest sensitivity was showed to erythromycin, gentamicin and chloramphenicol. Only one C. coli strain from turkey offal was resistant to gentamicin. Simultaneously multi drug resistance was defined. The aimed studies showed that 62% of C. jejuni and 53.8% of C. coli strains from chicken offal were resistant to two or more agents. In turkey origin isolates MDR was detected in 54.7% of C. jejuni and 53.3% of C. coli strains.

Susceptibility to patterns of ciprofloxacin among nalidixic acid-resistant Salmonella isolates collected in Banepa, Nepal from enteric fever patients

The present study determined the susceptibility to ciprofloxacin of nalidixic acid resistant <em>Salmonella</em> (NARS) isolated from enteric fever patients at Scheer Memorial Hospital, Banepa, Nepal, from June 2012 to December 2012. The antimicrobial sensitivity to nalidixic acid and ciprofloxacin was determined using modified Kirby-Bauer disc diffusion and broth dilution method according to the guidelines of the Clinical and Laboratory Standard Institute. <em>Salmonella</em> was isolated from 34 out of 992 (3.43%) blood cultures collected during the study period, and 10 (29.4%) isolates were identified as <em>Salmonella enterica</em> serotype Typhi, while 24 (70.6%) were identified as <em>Salmonella enterica</em> serotype Paratyphi. Out of the total isolates, 31 (91.2%) were nalidixic acid-resistant <em>Salmonella</em> (NARS). Among NARS, the minimum inhibitory concentration values for ciprofloxacin ranged from 0.25 to 2 mg/L and were constantly higher than those shown by the nalidixic acid-susceptible <em>Salmonella</em>. Therefore, in typhoid <em>Salmonella</em> nalidixic acid resistance may be the indicator of decreased susceptibility to ciprofloxacin.

REVIEW OF FIFTY CULTURE PROVEN SALMONELLA CASES

<p><strong>BACKGROUND:</strong> Enteric fever has huge global burden. Surrogate markers may have a role in early diagnosis. <strong>AIM:</strong> Unselected retrospective analysis of 50 culture positive Salmonella enterica cases for epidemiology, laboratory<br />markers, antibacterial susceptibility, therapy, and outcome was done. This was a retrospective chart review of electronic medical records for 50 patients with Salmonella in blood cultures for in our hospital during May 2009-April 2010. <strong>MATERIALS AND METHODS:</strong> Blood culture was by automated Bactec™ system and antimicrobial susceptibility test was performed by disk diffusion method or automated system Phoenix 100™. Sensitivity of Widal, S. typhi IgM, C-reactive protein (CRP), total leukocyte count, erythrocyte sedimentation rate (ESR), differential eosinophil and lymphocyte counts, and liver enzymes, was determined for these cases. <strong>RESULTS:</strong> Salmonella cases were seen in all ages from 8 months to 59 years; serotype Typhi was the most common (72%). Sensitivity of S. typhi IgM immunochromatographic test was 78.9%, of Widal was 88.8%, and that of CRP, serum aspartate transaminase (AST), and serum alanine transaminase (ALT) ranged from 81.8 to 89.4%. Eosinophil count of zero and ESR were found to be 78.2% and 85.7% sensitive. Nalidixic acid resistance was seen in 96% cases and ciprofloxacin resistance/intermediate sensitivity in 26% cases. Resistance was not seen with ceftriaxone, while ampicillin, chloramphenicol, and co-trimoxazole (ACCo) resistance was 4%. Seven cases relapsed mostly due to improper treatment associated with choice/dose/duration of antibiotics. <strong>CONCLUSIONS:</strong> Surrogate laboratory markers can be utilized pending culture results. Though antibiotics and vaccines against Salmonella, and good sanitation facilities are available, it causes morbidity in all sections, gender, and ages of society. Strategies of prevention have not been very successful; therefore, early detection and effective treatment can prevent its complications and relapses.</p>