SUB DIAPHRAGMATIC ABSCESS DUE TO SALMONELLA TYPHI: A RARE CASE REPORT FROM SUB-HIMALAYAN REGION

Salmonella Typhi causing subdiaphragmatic abscess is a rare entity. Intraabdominal abscess due to salmonella is usually associated with nontyphoid salmonella. We report a rare case of subdiaphragmatic abscess due to Salmonella Typhi in an 80 years old diabetic man. Ultrasound-guided drainage of fluid revealed pus cells on microscopy, and S. Typhi was cultured and identified by necessary biochemical tests and specific antisera. The patient succumbed to infection despite appropriate antibiotics, possibly due to co-morbid conditions. The case is presented for its rarity and to highlight atypical manifestations of S. Typhi in endemic regions

Anaerobic infections in patients admitted in various surgical units of a tertiary care hospital of north India: neglected but important

Background and Objectives: Anaerobic infections are usually caused by the host’s endogenous flora due to a breach in the anatomical barriers and Bacteroides spp. are the most notorious organisms associated with anaerobic infections. The identification of anaerobes has been a challenge since times. MALDI-TOF-MS is a boon for aiding the rapid detection of anaerobic organisms and has helped us to enlist the distribution of various anaerobic pathogens. Materials and Methods: This retrospective analysis (January 2018 to December 2019) was carried out in a tertiary care hospital in North India, in which the anaerobic microbiological profile of all patients admitted to surgical wards, ICU, and OPD of various departments (Orthopedics, Surgery, Gynecology, and Obstetrics) was reviewed. Samples received were immediately processed aerobically (5% sheep blood agar and Mac Conkeyagar) as well as anaerobically (RCM and freshly prepared sheep blood agar) as per the laboratory protocols. Results: Bacteroides fragilis (19.12%) was the most common anaerobe whereas among aerobes Escherichia coli (30.2%) followed by Klebsiella pneumoniae (10.34%) were most commonly isolated. The majority of patients were males (56%) and the most common presentation was with abscesses (21.4%). Polymicrobial infections (69.51%) outnumbered monomicrobial ones (30.48%). Conclusion: There is a paucity of literature on anaerobe isolation from surgical infections from our country which motivated us to study anaerobic infections and the high sample size in our institute enabled us to study surgical infections from an anaerobic perspective. This will add to the knowledge of microbiologists and clinicians. MALDI-TOF MS helped in rapid and accurate identification and hence we could report a wider spectrum of organisms in our study

Understanding polymicrobial biofilm dynamics: focus on Escherichia coli and its molecular interactions

AIM: To investigate bacterial interactions within dual-species biofilms on biliary stents and their role in stent blockage. BACKGROUND: Polymicrobial biofilms are critical in device-associated infections, including those in biliary stents, which are prone to biofilm formation due to duodenobiliary reflux, leading to stent blockage. This study identifies the microflora of biliary stents and examines their biofilm-forming capabilities to elucidate their role in stent occlusion. METHODS: Biliary stents were collected from patients with biliary obstructions. Microflora were identified using culture techniques and MALDI-TOF. Antimicrobial susceptibility was assessed via disk diffusion, while biofilm formation was measured using the crystal violet assay. Dual-culture biofilms were studied to understand polymicrobial dynamics, and gene expression in biofilms was analyzed at four time points. Statistical analysis was performed using GraphPad Prism 8.0 (p < 0.05). RESULTS: Scanning electron microscopy confirmed biofilms on biliary stents. Microbiological analysis identified 50 species of aerobic, anaerobic bacteria, and fungi. Biofilm formation significantly correlated with multidrug resistance. Based on the abundance, one isolate of E. coli was selected to study the dynamics of dual-species biofilm with K. pneumoniae, E. faecium, P. aeruginosa and S. hominis. Dual-species biofilms differed structurally and quantitatively from mono-species biofilms, influenced by the spatial arrangement of constituent bacteria (Figure 1) CONCLUSION: Delayed adhesion and varied interaction (both cooperatively and competitively) of E. coli with different bacterial species lead to delayed maturation of the biofilm. These interactions bolster bacterial virulence and survival in challenging conditions. Understanding these dynamics is crucial for preventing colonization of indwelling medical devices

Anaerobic Gram-Negative Bacteria: Role as a Reservoir of Antibiotic Resistance

Background: Anaerobic Gram-negative bacteria (AGNB) play a significant role as both pathogens and essential members of the human microbiota. Despite their clinical importance, there remains limited understanding regarding their antimicrobial resistance (AMR) patterns. This knowledge gap poses challenges in effectively managing AGNB-associated infections, as empirical treatment approaches may not adequately address the evolving resistance landscape. To bridge this research gap, we conducted a comprehensive study aimed at exploring the role of human AGNB as a reservoir of AMR. This can provide valuable insights for the prevention and management of anaerobic infections. Methods: We studied the prevalence of AMR and AMR determinants conferring resistance to metronidazole (nimE), imipenem (cfiA), piperacillin&ndash;tazobactam (cepA), cefoxitin (cfxA), clindamycin (ermF), chloramphenicol (cat) and mobile genetic elements (MGEs) such as cfiAIS and IS1186 associated with the cfiA and nim gene expression. These parameters were studied in Bacteroides spp., Fusobacterium spp., Prevotella spp., Veillonella spp., Sutterella spp., and other clinical AGNB. Results: Resistance to metronidazole, clindamycin, imipenem, piperacillin&ndash;tazobactam, cefoxitin and chloramphenicol was 29%, 33.5%, 0.5%, 27.5%, 26.5% and 0%, respectively. The presence of resistance genes, viz., nim, ermF, cfiA, cepA, cfxA, was detected in 24%, 33.5%, 10%, 9.5%, 21.5% isolates, respectively. None of the tested isolates showed the presence of a cat gene and MGEs, viz., cfiAIS and IS1186. The highest resistance to all antimicrobial agents was exhibited by Bacteroides spp. The association between resistant phenotypes and genotypes was complete in clindamycin, as all clindamycin-resistant isolates showed the presence of ermF gene, and none of the susceptible strains harbored this gene; similarly, all isolates were chloramphenicol-susceptible and also lacked the cat gene, whereas the association was low among imipenem and piperacillin&ndash;tazobactam. Metronidazole and imipenem resistance was seen to be dependent on insertion sequences for the expression of AMR genes. A constrained co-existence of cepA and cfiA gene in B. fragilis species was seen. Based on the absence and presence of the cfiA gene, we divided B. fragilis into two categories, Division I (72.6%) and Division II (27.3%), respectively. Conclusion: AGNB acts as a reservoir of specific AMR genes, which may pose a threat to other anaerobes due to functional compatibility and acquisition of these genes. Thus, AST-complying standard guidelines must be performed periodically to monitor the local and institutional susceptibility trends, and rational therapeutic strategies must be adopted to direct empirical management

Phenotypic and genotypic antimicrobial resistance in clinical anaerobic isolates from India

Abstract Background Antimicrobial resistance (AMR) in anaerobes remains a neglected field. The laborious procedures, non-compliance with the standard methodology and differences in interpretive breakpoints add variation in resistance data. Objectives To assess the phenotypic and genotypic resistance among clinically important anaerobes to six antibiotics frequently used as empirical therapy for anaerobic infections. Methods A total of 150 anaerobic isolates were recovered from clinical specimens. The antimicrobial susceptibility was determined by the breakpoint agar dilution method as per CLSI guidelines. The presence of genes encoding resistance to metronidazole (nim gene), imipenem (cfiA gene) and mobilizable insertion sequence (IS) elements was detected to comprehend their association with phenotypic resistance. Results This is a first study of its kind from the Indian subcontinent looking at the AMR and associated genes in anaerobes. Resistance to metronidazole, clindamycin, imipenem, piperacillin/tazobactam and cefoxitin was 32.6%, 42.6%, 0.6%, 38% and 35.3%, respectively. No resistance was observed to chloramphenicol. The nim gene was detected in 24.6% of isolates, of which 70.2% were resistant by phenotype. On sequencing, the PCR products of six random nim genes showed a close similarity to nimE of Bacteroides fragilis with 99% nucleotide and 100% amino acid sequence similarity. The cfiA gene, associated with imipenem resistance, was detected in 16% of isolates. Conclusions The possibility of isolates carrying AMR genes to become resistant to antibiotics by acquisition of IS elements mandates attention to periodically monitor the resistance patterns and geographic distribution of these genes and IS elements to understand the trends of AMR in anaerobes. </jats:sec