Metabolic Proteins Expression Up-Regulated in Blood-Borne Extensively Drug-Resistant Salmonella Typhi Isolates from Pakistan.

Background and Objectives: In the undertaken study, proteomics alterations of blood-borne XDR S. Typhi isolated from Pakistan were investigated using mass spectrometry. Materials and Methods: MDR and XDR S. Typhi total protein lysates were fractionated, digested, and processed for nanoflow LC-LTQ-Orbitrap MS analysis. Results: Among the 1267 identified proteins, 37 were differentially regulated, of which 28 were up-regulated, and 9 were down-regulated in XDR S. Typhi as compared to MDR S. Typhi. Based on the functional annotation, proteins found up-regulated are involved mainly in metabolic pathways (ManA, FadB, DacC, GpmA, AphA, PfkB, TalA, FbaB, OtsA, 16504242), the biosynthesis of secondary metabolites (ManA, FadB, GlpB, GpmA, PfkB, TalA, FbaB, OtsA), microbial metabolism in diverse environments (FadB, GpmA, PfkB, NfnB, TalA, FbaB), and ABC transporters (PstS, YbeJ, MglB, RbsB, ArtJ). Proteins found down-regulated are involved mainly in carbon metabolism (FadB, GpmA, PfkB, FalA, FbaB) and the biosynthesis of amino acids (GpmA, PfkB, TalA, FbaB). Most of the identified differential proteins were predicted to be antigenic, and matched with resistome data. Conclusions: A total of 28 proteins were up-regulated, and 9 were down-regulated in XDR S. Typhi. Further characterization of the identified proteins will help in understanding the molecular signaling involved in the emergence of XDR S. Typhi.

Molecular identification and differential proteomics of drug resistant Salmonella Typhi.

This study aimed to elucidate differentially expressed proteins in drug resistant Salmonella Typhi. Among 100 samples, S. typhi were identified in 43 samples. In drug susceptibility profile, 95.3% (41/43), 80% (35/43) and 70% (30/43) resistances were observed against Nalidixic acid, Ampicillin, and Chloramphenicol respectively. No resistance was observed against Imipenum and Azithromycin while only 11% (5/43) isolates were found resistant to Ceftriaxone. Mass spectrometric differential analysis resulted in 23 up-regulated proteins in drug resistant isolates. Proteins found up-regulated are involved in virulence (vipB, galU, tufA, and lpp1), translation (rpsF, rpsG, rplJ, and rplR), antibiotic resistance (zwf, phoP, and ompX), cell metabolism (metK, ftsZ, pepD, and secB), stress response (ridA, rbfA, and dps), housekeeping (gapA and eno) and hypothetical proteins including ydfZ, t1802, and yajQ. These proteins are of diverse nature and functions but highly interconnected. Further characterization may be helpful for elucidation of new biomarker proteins and therapeutic drug targets.

Antimicrobial Resistance of Shigella flexneri in Pakistani Pediatric Population Reveals an Increased Trend of Third-Generation Cephalosporin Resistance.

The rapid emergence of resistance to third-generation cephalosporins in Shigella flexneri is crucial in pediatric shigellosis management. Limited studies have been conducted on molecular pattern of antibiotic resistance of S. flexneri in diarrhea endemic areas of Pakistan. The aim of the study was to analyze the antimicrobial resistance of S. flexneri isolated from pediatric diarrheal patients in Peshawar, Pakistan. A total of 199 S. flexneri isolates (clinical, n = 1 55 and non-clinical, n = 44) were investigated for drug resistance and mutational analysis of selected drug resistance genes. All isolates were found to be highly resistant to amoxicillin/clavulanic acid (88%), followed by trimethoprim-sulfamethoxazole (77%), chloramphenicol (43%), and quinolones (41.6%). About 34.5% S. flexneri isolates were found to be resistant to third-generation cephalosporin. None of the isolates was resistant to imipenem, piperacillin-tazobactam, and amikacin. Interestingly high frequency of third-generation cephalosporin resistance was observed in S. flexneri isolated from non-clinical samples (49%) when compared to clinical samples (30.5%). Furthermore, the most prevalent phenotypic-resistant patterns among third-generation cephalosporin-resistant isolates were AMC,CAZ,CPD,CFM,CRO,SXT (13%) followed by OFX,AMC,CAZ,CPD,CFM,CRO,SXT,NA,CIP (10%). The most frequently detected resistance genes were trimethoprim-sulfamethoxazole (sul2 = 84%), beta-lactamase genes (blaOXA = 87%), quinolones (qnrS = 77%), and chloramphenicol (cat = 64%). No mutation was detected in any drug-resistant genes. We are reporting for the first time the sequence of the blaTEM gene in S. flexneri. Furthermore, high third-generation cephalosporin resistance was observed in the patients who practiced self-medication as compared to those who took medication according to physician prescription. This study shows the high emergence of third-generation cephalosporin-resistant S. flexneri isolates, which is a potential threat to the community in the country. This finding will be helpful to develop a suitable antibiotic prescription regime to treat shigellosis.

Salmonella Typhi from Northwest Pakistan: Molecular Strain Typing and Drug Resistance Signature.

Objective: To determine the molecular strain typing and drug resistance pattern of Salmonella enterica serovar Typhi prevalent in Northwest Pakistan. Methodology: A total of 2,138 blood samples of suspected typhoid patients from Northwest Pakistan were collected followed by identification of Salmonella Typhi through biochemical, serological, and species-specific fliC-d gene amplification. These isolates were typed by variable-number tandem repeat (VNTR) profiling and investigated for drug resistance. Results: The overall prevalence of Salmonella Typhi was found to be 8.8% (n = 189). Thirty different VNTR strain types of Salmonella Typhi were detected and the most prevalent strain types were T1 and T4, whereas T27 was less prevalent strain. Among the 189 isolates 175 (92.5%) isolates were multidrug resistant, whereas 12 (5.8%) isolates were extensively drug resistant. Resistance to imipenem in Salmonella Typhi was not observed. Most of the isolates have genes encoding for resistance to fluoroquinolones, including gyrA (n = 164), gyrB (n = 160), parC (n = 164), parE (n = 160), ac(6')-ib-cr (n = 163), qnrS (n = 15), and qnrB (n = 3). Similarly, chloramphinicol (cat; n = 147), azithromycin (msrA; n = 3), and co-trimoxazole (dfrA7; n = 145) resistance genes were detected among Salmonella Typhi isolates. Conclusion: In this study, T1 and T4 type Salmonella Typhi strains were predominantly prevalent in Northwest Pakistan. Antibiotic resistance among Salmonella Typhi isolates were observed. Findings of the study would be helpful to devise an appropriate antibiotic policy to control the emergence of drug-resistant Salmonella Typhi in Pakistan.

Association of Serotype With Antimicrobial Resistance Patterns Among Shigella flexneri Isolates From Pakistan: The Importance of Serotype 2b.

BACKGROUND: Shigella flexneri is an emerging threat in low socioeconomic countries including Pakistan. No previous data is available on the association between S. flexneri serotypes and antimicrobial resistance in Pakistan. OBJECTIVES: The objective of the present study was to assess the association between serotypes and antimicrobial resistance patterns among S. flexneri isolated from clinical and nonclinical samples. METHODS: A total of 199 S. flexneri isolates were subjected to molecular serotyping and antibiotic resistance. RESULTS: The most prevalent S. flexneri serotype was 2b (38%) followed by 1b (24%), 7a (20%), 2a (11%), 1d (5%) and Y (2%). The phylogenetic reconstruction showed 12 clades among which the clades II, III, V, VIII, IX and XI have consisted of serotypes that were found both in human population and environment samples. A high level of multidrug resistance (MDR) was observed in serotype 2b (37.68%) followed by 1b (19.5%) and 7a (19.5%), 2a (11.5%), 1d (5%) and Y (2%). All isolates of serotype 2b showed high level of resistance to amoxicillin/clavulanic acid (100%) followed by quinolone (74.6%) and trimethoprim-sulfamethoxazole (54.6%). Interestingly, none of the serotype was resistant to piperacillin-tazobactam, imipenem and amikacin. The most frequently detected resistance genes among serotype 2b were blaOXA (100%) followed by qnrS (88%), cat (81%) and sul2 (63%). CONCLUSION: The most frequent S. flexneri serotype was 2b while 1d and Y was first time reported in Pakistan. High frequency of MDR serotypes of S. flexneri is a serious threat in diarrhea endemic regions and thus require urgent strategies for its continuous monitoring and prevention.

Shigella flexneri: an emerging pathogen.

Shigella flexneri is a leading etiologic agent of diarrhea in low socioeconomic countries. Notably, various serotypes in S. flexneri are reported from different regions of the world. The precise approximations of illness and death owing to shigellosis are missing in low socioeconomic countries, although it is widespread in different regions. The inadequate statistics available reveal S. flexneri to be a significant food and waterborne pathogen. All over the world, different antibiotic-resistant strains of S. flexneri serotypes have been emerged especially multidrug-resistant strains. Recently, increased resistance was observed in cephalosporins (3rd generation), azithromycin, and fluoroquinolones. There is a need for a continuous surveillance study on antibiotic resistance that will be helpful in the update of the antibiogram. The shigellosis burden can be reduced by adopting preventive measures like delivery of safe drinking water, suitable sanitation, and development of an effective and inexpensive multivalent vaccine. This review attempts to provide the recent findings of S. flexneri related to epidemiology and the emergence of multidrug resistance.

Molecular epidemiology of Shigella flexneri isolated from pediatrics in a diarrhea-endemic area of Khyber Pakhtunkhwa, Pakistan.

Shigella flexneri is considered as an important causative agent of Shigellosis causing diarrhea in the countries with a low socioeconomic status. No study has been carried out on the molecular prevalence of S. flexneri in Khyber Pakhtunkhwa, Pakistan. So this study was designed to evaluate the molecular prevalence of S. flexneri and their associated risk factors. A total of 2014 diarrheal stool samples were collected from January 2016 to May 2017 from pediatrics patients of Khyber Pakhtunkhwa followed by identification of S. flexneri through biochemical, serological, and molecular methods. The overall prevalence of Shigella species was found to be 7.9% (n = 160). The predominant Shigella specie was S. flexneri (n = 155, 96.8%) followed by S. boydii (n = 5, 3.1%). Interestingly, no sample was found positive for S. sonnei and S. dysenteriae. The majority of Shigellosis cases occurred from June to September. Potential risk factors related with Shigellosis were unhygienic latrine usage, bad hand washing, and consumption of unhygienic food and water, and pipe leakage in the sewage system. In this study, we have observed a high number of Shigellosis cases especially those caused by S. flexneri. It is suggested that effective health awareness programs should be organized by the regional health authorities to minimize the magnitude of pediatrics Shigellosis.