Comprehensive Analysis of Salmonella Species Antibiogram and Evolving Patterns in Empirical Therapy: Insights From Tertiary Care Hospitals in Peshawar, Pakistan

Background Typhoid fever presents a significant challenge in developing nations, exacerbated by the emergence of antibiotic-resistant strains due to widespread prevalence and overuse of antibiotics. This study seeks to assess the antibiogram profiles of Salmonella species isolated from blood cultures of patients hospitalized at two prominent tertiary care hospitals in Peshawar, Pakistan: Khyber Teaching Hospital (KTH) and Hayatabad Medical Complex (HMC). By examining these profiles, the research aims to provide valuable insights into the evolving landscape of antibiotic resistance in the context of typhoid fever management. Materials and Methods This retrospective cross-sectional study utilized data gathered from two hospitals in Peshawar, KTH and HMC. Cases of enteric fever were identified based on positive blood cultures for Salmonella species. The study encompasses demographic information, seasonal prevalence, and antibiogram profiles of 3,137 cases that were presented between 2017 and 2023. Results Among the total 3,137 cases, males accounted for the majority, comprising 63% (2,044 cases). Particularly notable was the clustering of cases among children and adolescents aged one to 24 years. The incidence peaked during the months of summer and spring, from April to September. In terms of Salmonella Typhi isolates, considerable resistance was noted against first-line antibiotics such as amoxicillin/clavulanate (80.1%), co-trimoxazole/trimethoprim-sulfamethoxazole (66.6%), and chloramphenicol (86.9%), as well as against ceftriaxone (79.7%) and ciprofloxacin (51.6%). Conversely, certain antibiotics displayed higher sensitivity patterns, including meropenem (97.8%), doripenem (99.5%), imipenem (97.7%), ertapenem (96.5%), polymyxin B (99.4%), colistin (98.1%), and tigecycline (97.3%). Despite a limited sample size of 214 specimens, fosfomycin demonstrated a remarkable sensitivity of 93.4%. Sensitivities of amikacin and gentamicin were 90.7% and 81.5%, respectively. However, the sensitivity of azithromycin was concerning, standing at 66.5%. The antibiogram pattern for Salmonella exhibited significant and drastic changes. Conclusion In conclusion, this study sheds light on a higher prevalence of typhoid fever among males, with a notable seasonal peak observed during the summer and spring months. The age group most affected spans from one to 24 years. Salmonella isolates displayed significant resistance to conventional first-line antibiotics, alongside ciprofloxacin and third-generation cephalosporins. Azithromycin exhibited lower sensitivity compared to amikacin, gentamicin, and fosfomycin. The research advocates for the empirical use of amikacin, gentamicin, fosfomycin, and meropenem in the treatment of typhoid fever in Pakistan. Urgent measures, including regular Salmonella antibiogram surveillance, antibiotic stewardship, public health education, and Salmonella vaccination programs, are deemed crucial for primary disease prevention.

Influence of Bacterial Contamination and Antibiotic Sensitivity on Cryopreserved Sperm Quality of Indian Red Jungle Fowl

Aims: Bacterial contamination may occur in feces during collection and processing of semen. Bacteria not only compete for nutrients with spermatozoa but also produce toxic metabolites and endotoxins and affect sperm quality. The aim of the present study was to investigate the effect of antibiotic supplementation on the sperm quality of Indian red jungle fowl, estimation and isolation of bacterial species and their antibiotic sensitivity. Materials and Methods: Semen was collected and initially evaluated, diluted, and divided into six experimental extenders containing gentamicin (2.5 μg/mL), kanamycin (31.2 μg/mL), neomycin (62.5 mg/mL), penicillin (200 U/mL), and streptomycin (250 μg/mL), and a control having no antibiotics were cryopreserved and semen quality was evaluated at post-dilution, post-cooling, post-equilibration, and post-thawing stages (Experiment 1). A total aerobic bacterial count was carried out after culturing bacteria (Experiment 2) and subcultured for antibiotic sensitivity (Experiment 3). Results: It was shown that penicillin-containing extender improved semen quality (sperm motility, plasma membrane integrity, viability, and acrosomal integrity) compared with the control and other extenders having antibiotics. The bacteria isolated from semen were Escherichia coli, Staphylococcus spp., and Bacillus spp. Antibiotic sensitivity results revealed that E. coli shows high sensitivity toward neomycin, kanamycin, and penicillin. Staphylococcus spp. shows high sensitivity toward streptomycin, neomycin, and penicillin. Bacillus spp. shows high sensitivity toward kanamycin and penicillin. Conclusions: It was concluded that antibiotics added to semen extender did not cause any toxicity and maintained semen quality as that of untreated control samples, and penicillin was identified as most effective antibiotic. It is recommended that penicillin can be added to the semen extender for control of bacterial contamination without affecting the semen quality of Indian red jungle fowl.

Etiology, Microbiological Isolates, and Antibiotic Susceptibilities in Inpatients with Refractory Auricular Perichondritis: A 10-Year Retrospective Study

Purpose

This study aimed to elucidate the etiologies, microbiological profiles, antibiotic susceptibilities of bacteria and outcomes of patients with auricular perichondritis.

Patients and Methods

This was a single-center retrospective study. Inpatients diagnosed with auricular perichondritis at a university teaching hospital in eastern China between January 2013 and December 2022 were included in this study.

Results

A total of 127 patients were enrolled, with an average age of 50.6 ± 16.9 years. In addition to cases in which the etiology remained undetermined in 37% of the patients, postoperative infection emerged as the predominant cause (37.8%), followed by trauma (18.1%). Among the 61 cultured isolates, 21.3% were gram-positive bacteria, 55.7% were gram-negative bacteria, and 23.0% were fungal isolates. The most frequent isolate was Pseudomonas aeruginosa (30/61, 49.2%). Notably, the incidence of fungal infections was markedly higher among postoperative patients than among post-traumatic patients (41.7% vs 7.1%, p = 0.03). The proportions of gram-negative bacteria (60.0% vs 50.0%) and fungal isolates (28.6% vs 15.4%) exhibited an increasing trend during the period of 2018-2022, as compared to the previous period of 2013-2017. The bacterial isolates exhibited high susceptibility to vancomycin (100%), amikacin (100%), cefepime (94.6%), and ceftazidime (90.9%). In contrast, overall susceptibility to fluoroquinolones was relatively low (65.2-67.4%), demonstrating a declining trend in the susceptibility of Pseudomonas aeruginosa. Notably, 78.7% of the patients received an initial treatment regimen covering Pseudomonas aeruginosa. Within 30 days of discharge, 8.5% (6/71) experienced an infection recurrence.

Conclusion

Auricular perichondritis predominantly originates from iatrogenic (postoperative) infections. Antibiotic therapy covering Pseudomonas aeruginosa is a sensible and appropriate empirical treatment in the majority of patients with auricular perichondritis. However, increased resistance to fluoroquinolones has become a notable concern, suggesting the need to seek new, more aggressive strategies.

Pregnancy-associated asymptomatic bacteriuria and antibiotic resistance in the Maternity and Children's Hospital, Arar, Saudi Arabia

INTRODUCTION

The Ministry of Health in Saudi Arabia provides comprehensive antenatal care for all pregnant women with all required investigations. However, it does not include urine culture for diagnosis of asymptomatic bacteriuria (ASB). This is the first study to evaluate the prevalence of ASB among pregnant females, identify the causative organisms and determine their antibiotic susceptibility patterns in the Maternity and Children's Hospital, Arar, Saudi Arabia.

METHODOLOGY

This cross-sectional study included 400 pregnant women attending an antenatal clinic. Two midstream urine samples were aseptically collected and screened using standard microbiological techniques including microscopic examination, dipstick testing, and urine culture. In order to interpret the urine culture results, ≥ 105 CFUs/mL was considered significant bacteriuria. Identification of the isolates and their antibiotic sensitivity testing was performed using the Vitek 2 system (BioMérieux, Marcy l'Etoile, France) with the available test kits.

RESULTS

The prevalence of ASB was 8.25% (35/400). Significant positive correlations (p ˂ 0.05) were detected between positive urine culture results and random blood sugar, leucocytes, nitrites, pus cells, urine red blood cells, epithelial cells, and mucus. Escherichia coli was the most common causative organism (45.7%), followed by Staphylococcus aureus (22.9%). Klebsiella pneumoniae represented 11.4% of the isolates. Most of the isolated Gram-positive organisms were sensitive to many of the tested antibiotics; most of the detected Gram-negative isolates were resistant.

CONCLUSIONS

ASB caused by antibiotic resistant organisms is alarming. Screening for ASB during pregnancy using urine culture and sensitivity testing is of vital importance to improve the maternal and neonatal outcome.

Platinum Nanoparticles Prevent the Resistance of Pseudomonas aeruginosa to Ciprofloxacin and Imipenem: Mechanism Insights

Metal nanoparticles (MNPs) have recently gained extensive attention due to their broad-spectrum prospect, particularly in biomedical application. Here, we reveal that long-term exposure to platinum nanoparticles (Pt NPs) increases the susceptibility of Pseudomonas aeruginosa PAO1 to imipenem and ciprofloxacin. We exposed PAO1 to Pt NPs (a series of doses, varying from 0.125 to 35 μg/mL) for 60 days and characterized the evolved strains (ES) and compared with wild type (WT) to understand the mechanism of heightened sensitivity. We found that overexpression of oprD and downregulation of mexEF-oprN facilitate the intracellular accumulation of antibiotic, thus increasing susceptibility. Furthermore, loss-of-function mutations were discovered in regulators lasR and mexT. Cloning intact lasR from wild-type (WT) into ES slightly improves imipenem resistance. Strikingly, cloning mexT from WT into ES reverts the imipenem and ciprofloxacin resistance to the original level. Briefly, the increase of membrane permeability controlled by mexT made PAO1 greatly susceptible to imipenem and ciprofloxacin, and the decrease of quorum sensing mediated by lasR made PAO1 slightly susceptible to imipenem. Overall, these results reveal an antibiotic susceptibility mechanism from prolonged exposure to MNPs, which provides a promising approach to prevent antibiotic resistance.

[Taxonomic characteristics and antibiotic susceptibility of microorganisms verified in the expressed prostate secretion in post-COVID-19 patients with recurrent chronic bacterial prostatitis]

INTRODUCTION

Recurrent chronic bacterial prostatitis (rCBP) is a hard-to diagnosis-and-treat disease which there is no consensus. A particularly difficult cohort is represented by patients who had COVID-19. The study aimed to evaluate the taxonomic structure and sensitivity to antibacterial drugs of microorganisms verified in expressed prostate secretion (EPS) in rCBP-patients who had COVID-19.

MATERIALS AND METHODS

A multicenter, prospective, randomized study was conducted with the inclusion of 52 rCBP patients who had COVID 19, in which the taxonomic structure and susceptibility were studied to antibacterial drugs of microorganisms that were verified and dominated in the EPS. Bacteriological study was carried out using an extended set of selective nutrient media and special cultivation conditions. Antibiotic susceptibility was determined in the taxa of microbiota dominating in the EPS.

RESULTS

The mean age of the patients was 34.8+/-5.2 years, the duration of rCBP was 5.7+/-2.3 years. In all patients, various variants of aerobic-anaerobic compositions of microorganisms were recorded in the life cycle. A total of 27 microbiota taxa were isolated. The aerobic cluster was represented by 16 genera and/or species, the anaerobic cluster by 11. When studying antibiotic susceptibility to antibacterial drugs, an increase in antibiotic resistance of the most microorganisms isolated was revealed.

CONCLUSIONS

The taxonomic structure of microorganisms in rCBP-patients who had COVID-19 in all cases was characterized by complex and new variants of aerobic-anaerobic associations of microorganisms. When studying the antibiotic susceptibility, multi-resistant and pan-resistant bacteria were identified that is a real threat to this category of patients.

Frequency of Urinary Tract Infection Among Patients Undergoing Implant Fixation for Acute Trauma

OBJECTIVE

This study aims to determine the frequency of urinary tract infection (UTI), identify the isolated bacteria, and assess antibiotic sensitivity in patients undergoing orthopedic implant fixation for hip fractures.

METHODOLOGY

After ethical approval from the institutional review board, this retrospective cross-sectional study was conducted at the Orthopedic Surgery Department of Dow University Hospital Karachi from June 2022 to June 2023. Through non-probability consecutive sampling, 186 patients above 16 years of age, of either gender, presenting with hip fractures such as intracapsular or extracapsular fractures, who underwent surgical fixation, were included in the study. A urine sample for urinalysis of these patients was sent on admission. Patients who presented with open fractures or those treated with conservative management were excluded from the study. The fracture diagnosis was confirmed on radiographs. All other relevant baseline investigations were also performed before surgery, per protocol, and urine-detailed and cultured reports were followed. In addition, each patient was asked about common symptoms of UTI before surgery and then diagnosed with UTI on positive urine culture and sensitivity (CS).

RESULTS

Out of 186 hip fracture patients, 98 (52.7%) were males and 88 (47.3%) were females, with a mean age of 61.03 ± 16.43 (16-96) years. Pre-operative UTI symptoms were reported by 79 patients, including dysuria (16; 20.3%), polyuria (19; 24.0%), and burning (44; 55.7%). UTI was diagnosed on culture and sensitivity report in 65 (34.9%) patients with Escherichia coli as commonly diagnosed bacteria 35 (53.8%), followed by Enterococcus 8 (12.4%), Klebsiella 7 (10.9%), Pseudomonas aeruginosa 3 (4.7%), and Acinetobacter 2 (3.1%) patients. E. coli was sensitive to amikacin, amoxicillin/clavulanic acid, ampicillin, cefixime, ceftriaxone, cefuroxime, ciprofloxacin, colistin, cotrimoxazole, fosfomycin, gentamycin, levofloxacin, meropenem, nitrofurantoin, polymyxin B, and piperacillin-tazobactam.

CONCLUSION

Urinary tract infection is common in patients undergoing orthopedic implant fixation for hip fractures, which can lead to potentially serious outcomes. Overall, hygiene, prompt treatment, and standard protocol should be utilized to treat those infected and minimize the spread.

Wax Ester and Triacylglycerol Production in Acinetobacter baumannii: Role in Osmostress Protection, Reactive Oxygen Species, and Antibiotic Sensitivity

Wax esters (WEs) are neutral lipids that are produced by many different bacteria as potential carbon and energy storage compounds. Comparatively little is known about the role of WE in pathogenic bacteria. The opportunistic pathogen Acinetobacter baumannii is a major cause of hospital-acquired infections worldwide. Salt and desiccation resistance foster A. baumannii infections such as urinary tract infections and allow for reinfection when bacteria are taken up from dry surfaces in the hospital environment. Here we report on WE and triacylglycerol (TAG) production in A. baumannii as a response to nitrogen limitation and high salt stress. Fatty acids and fatty alcohols with chain lengths of C16 and C18 were identified as the most prominent WE constituents. We identified the terminal key enzyme of WE biosynthesis, the bifunctional wax ester synthase/acylCoA:diacylglycerol acyltransferase (WS/DGAT) encoded by the wax/dgat gene, and demonstrated that transcription of wax/dgat and production of WS/DGAT are independent of the nitrogen concentration. A Δwax/dgat mutant was impaired in growth in the presence of high salt concentration and was more sensitive to imipenem and reactive oxygen species.

[Low-Molecular Thiols as a Factor Improving the Sensitivity of Escherichia coli Mutants with Impaired ADP-Heptose Synthesis to Antibiotics]

Low molecular-weight thiols as glutathione and cysteine are an important part of the cell's redox regulation system. Previously, we have shown that inactivation of ADP-heptose synthesis in Escherichia coli with a gmhA deletion induces the oxidative stress. It is accompanied by rearrangement of thiol homeostasis and increased sensitivity to antibiotics. In our study, we found that restriction of cysteine metabolism (ΔcysB and ΔcysE) and inhibition of glutathione synthesis (ΔgshAB) lead to a decrease in the sensitivity of the ΔgmhA mutant to antibiotics but not to its expected increase. At the same time, blocking of the export of cysteine (ΔeamA) or increasing import (Ptet-tcyP) into cells of the oxidized form of cysteine-cystine leads to an even greater increase in the sensitivity of gmhA-deleted cells to antibiotics. In addition, there is no correlation between the cytotoxic effect of antibiotics and the level of reactive oxygen species (ROS), the total pool of thiols, or the viability of the initial cell population. However, a correlation between the sensitivity to antibiotics and the level of oxidized glutathione in cells was found in our study. Apparently, a decrease in the content of low-molecular-weight thiols saves NADPH equivalents and limits the processes of protein redox modification. This leads to increasing of resistance of the ΔgmhA strain to antibiotics. An increase in low-molecular-weight thiols levels requires a greater expenditure of cell resources, leads to an increase in oxidized glutathione and induces to greater increase in sensitivity of the ΔgmhA strain to antibiotics.

Pathology, virulence-associated gene profiling, antimicrobial susceptibility, and pathogenicity of untypeable capsular serotypes of Pasteurella multocida isolated from slaughtered pigs of India

Pasteurella multocida is widely distributed in all pig-rearing countries, affecting the economic viability and profitability of pig production. The present research highlights the molecular characterization and pathology of untypeable capsular serotypes of P. multocida in slaughtered pigs from prominent pig-rearing states of India. The prevalence of Pasteurellosis was 27.17% by Pasteurella multocida specific Pasteurella multocida specific PCR (PM-PCR). assay, while isolation rate was 7.62%. The microscopic lesions of bronchopneumonia, tonsillitis, and the presence of bacterial antigens in immunohistochemistry confirmed P. multocida with pathologies. In capsular typing, the majority of the isolates were untypeable with prevalence of 52.15% and 43.58% in molecular and microbiological methods, respectively. All the isolates showed the uniform distribution of virulence genes such as exbB, nanB, sodC, plpB, and oma87 (100%), while the variations were observed in ptfA, hasR, ptfA, pfhA, hsf-1, and plpE genes. The untypeable isolates showed higher prevalence of hsf-1 gene as compared to others. The untypeable serotypes showed a higher degree of resistance to ampicillin, amoxicillin, and penicillin antibiotics. The mouse pathogenicity testing of untypeable capsular isolates confirmed its pathogenic potential. The higher frequency of pathogenic untypeable isolates with antibiotic resistance profile might pose a serious threat to the pigs, and therefore, preventive measures should be adopted for effective control.

Exploration of probiotic attributes in lactic acid bacteria isolated from fermented Theobroma cacao L. fruit using in vitro techniques

Probiotics are known for their health-promoting properties and are recognized as beneficial microorganisms. The current investigation delves into the isolation and comprehensive in vitro characterization of lactic acid bacteria (LAB) obtained from the Indian-origin Theobroma cacao L. Forastero variety to assess their potential as probiotic candidates. Eleven LAB isolates were obtained, and among them, five exhibited classical LAB traits. These five isolates underwent rigorous in vitro characterization to evaluate their suitability as probiotics. The assessments included resilience against acid and bile salts, which are crucial for probiotic viability. Additionally, the isolates were subjected to simulated gastric and pancreatic fluids and lysozyme exposure to assess their survival rates. Auto- aggregation, co-aggregation, hydrophobicity, and exopolysaccharide production were also examined. The inhibitory potential of α-glucosidase, an enzyme related to glucose metabolism, was measured, and antioxidant activity was evaluated using DPPH and ABTS assays. A safety assessment was conducted to confirm the non-pathogenic nature of the isolates. Among the five isolates, CR2 emerged as a standout candidate with maximal bile salt hydrolase activity, phenol resistance, and lysozyme resistance. CR2 and CYF3 exhibited notable survival rates under simulated conditions. The isolates displayed variable degrees of auto-aggregation, co-aggregation, and hydrophobicity. CR2 exhibited the highest exopolysaccharide production (0.66 mg/mL), suggesting diverse applications in the food industry. CR2 also demonstrated the highest inhibition rate against α-glucosidase (56.55%) and substantial antioxidant activity (79.62% DPPH, 83.45% ABTS). Safety assessment confirmed the non- pathogenic nature of the isolates. Molecular characterization identified CR2 as Lactococcus lactis subsp. lactis and CYF3 as Limnosilactobacillus fermentum. Both strains exhibited commendable probiotic and technological attributes, positioning them as promising candidates for functional foods and beyond. This study provides valuable insights into the in vitro characterization of LAB isolated from Indian Theobroma cacao L., highlighting their potential as probiotic candidates with advantageous traits, including survival in hostile conditions, beneficial enzymatic activities, bioactivity, and other essential attributes.

Role of Matrix-Assisted Laser Desorption Ionization-Time-of-Flight Mass Spectrometry for Species Identification of Acinetobacter Strains

Introduction   Acinetobacter species has become a leading cause of nosocomial infections in recent years. Objectives  The aim of the study was to establish the usefulness of matrix-assisted laser desorption ionization-time-of-flight (MALDI-TOF) mass spectrometry (MS) for the identification of Acinetobacter species with respect to conventional biochemical methods and MicroScan WalkAway 96 Plus system and to compare the antibiotic susceptibility test results Kirby-Bauer disk diffusion method with MicroScan WalkAway 96 Plus automated identification and antimicrobial susceptibility testing system. Materials and Methods  The study sample comprised 100 clinical isolates of Acinetobacter species. They were all identified using MALDI-TOF MS and compared with other two identification systems. Statistical Analysis  Comparison of categorical variables by Fisher's exact test or Pearson's chi-square test was done. All statistical tools were two tailed, and a significant level p  < 0.05 was used. All statistical tests were performed using SPSS v22.0 (Armonk IBM Corp., New York, United States). Cohen's kappa coefficients were also calculated and used as applicable. Results  MALDI-TOF MS revealed 92 A. baumannii , 2 Acinetobacter nosocomialis , 3 Acinetobacter lwoffii , and 1 each was identified as Acinetobacter junii , Acinetobacter johnsonii , and Acinetobacter tandoii . There was moderate agreement between identification by MicroScan WalkAway and MALDI-TOF, and substantial agreement between conventional biochemical tests and MALDI-TOF. We found that there was a 100% categorical agreement with respect to susceptibility of aminoglycosides (amikacin, gentamicin, tobramycin) and cephalosporins (ceftazidime, cefepime, cefotaxime) between disk diffusion method and MicroScan WalkAway 96 Plus system. Total of 16 errors were observed. Conclusion  Although MALDI-TOF MS could be useful to identify A. baumannii but not other species in the genus, it is a rapid, reliable method and can be routinely used in clinical laboratories.

Common Resistance Patterns in the Burn Unit of a Tertiary Care Center: A Retrospective Observational Study

Background Nosocomial bacterial infections have been one of the major concerns in the healthcare system. Burn patients, specifically severe cases, are at a high risk of developing bacterial infections compared to others. The most frequent cultures among burn patients are Staphylococcus aureus, Pseudomonas aeruginosa,and Acinetobacter baumannii. There is a scarcity of local data showing the most common infections in burn patients. This research aimed to determine the most common organisms that cause infections in burn unit patients and the antibiotic sensitivity and resistance patterns in King Abdulaziz Medical City (KAMC) in Jeddah. Methodology In this cross-sectional study, data were collected from patients' files into a data collection sheet. All patients in the burn unit with a positive culture were included in the study using a convenient sampling technique from Best-Care, KAMC electronic medical records. Burn patients with negative culture results and patients who were admitted to the plastic surgery ward for reasons other than burns were excluded. For sample size calculation, convenience sampling of 109 patient medical charts, over the study period from June 2016 to November 2021, was selected for data extraction, analysis, and reporting. Results Pseudomonas aeruginosa was the leading cause of infection in burn patients comprising 33.9% of the cases. Enterobacter cloacae was the second most frequent cause of infection among burn patients (27.5%). Klebsiella pneumoniae was the third most frequent cause of infection (26.6%) while Acinetobacter baumannii was the fourth most frequent cause of infection in burn patients (22.9%). Conclusions Understanding the local epidemiology of bacterial infections will be crucial for the development of treatment guidelines designed to standardize initial antibiotic use, reduce hospital-acquired infections, and reduce drug resistance. More attention should be paid to gram-negative bacteria, specifically Pseudomonas aeruginosa and Enterobacter Cloacae.

Exploring the Potential of a Genome-Reduced Escherichia coli Strain for Plasmid DNA Production

The global demand for nucleic acid-based vaccines, including plasmid DNA (pDNA) and mRNA vaccines, needs efficient production platforms. However, conventional hosts for plasmid production have encountered challenges related to sequence integrity due to the presence of insertion sequences (ISs). In this study, we explored the potential of a genome-reduced Escherichia coli as a host for pDNA production. This strain had been constructed by removing approximately 23% of the genome which were unessential genes, including the genomic unstable elements. Moreover, the strain exhibits an elevated level of NADPH, a coenzyme known to increase plasmid production according to a mathematical model. We hypothesized that the combination of genome reduction and the abundance of NADPH would significantly enhance pDNA production capabilities. Remarkably, our results confirmed a three-fold increase in pDNA production compared to the widely employed DH5α strain. Furthermore, the genome-reduced strain exhibited heightened sensitivity to various antibiotics, bolstering its potential for large scale industrial pDNA production. These findings suggest the genome-reduced E. coli as an exciting candidate for revolutionizing the pDNA industry, offering unprecedented efficiency and productivity.

Kerstersia gyiorum isolated for the first time from two patients with neurodegenerative disease: report of two unusual cases and a review of the literature

With the development of matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) and 16S ribosomal RNA (rRNA) gene sequencing, increasing numbers of new microorganisms are being discovered. In this report, Kerstersia gyiorum was isolated for the first time from the sputum of two elderly patients with neurodegenerative disease, and integrated traditional Chinese and Western medicine was used for treatment. The bacteria's growth characteristics, biochemical reaction characteristics, sensitivity to antibiotics, and the patients' treatment are described, with a review of previous reports.

In vitro biochemical characterization and identification of hemolytic bacteria associated with life history of Culicoides peregrinus (Diptera: Ceratopogonidae), a vector of bluetongue virus

Gut bacterial communities in insects provide several beneficial roles like nutrition, digestion, fecundity, and survival of the host. The microbial communities of Culicoides spp. (Diptera: Ceratopogonidae) vary with parity, developmental stages, and environmental factors. Previous studies have revealed the presence of hemolytic bacteria in adult Culicoides peregrinus Kieffer (Diptera: Ceratopogonidae), an important vector of bluetongue virus (BTV). Our objectives were (i) to identify bacterial communities with hemolytic activities associated with all life stages and (ii) to compare between reared and field-collected adults including age graded females. Bacterial identification followed Sanger sequencing of 16S rRNA. In vitro biochemical characterizations including antibiotic sensitivity tests were also done. The majority of bacterial species were beta hemolytic with one, Alcaligenes faecalis, showing alpha hemolysis. Most bacterial species were observed in field-collected adults except Proteus spp. Throughout the life history of the vector, Bacillus cereus (CU6A, CU1E) and Paenibacillus sp. (CU9G) were detected indicating their possible role in blood digestion within the gut of this vector species. In vivo hemolytic activities of these culturable bacterial communities within this vector may be addressed in future. These hemolytic bacterial communities may be targeted to develop novel and effective strategies for vector control.

The Effectiveness of Antibiotics in Managing Bacterial Infections on Bite Sites following Snakebite Envenomation

Snakebite envenomation (SBE) is a life-threatening medical emergency with a high mortality rate. Common secondary complications following SBE, such as wound infections, are significant due to their impact on worsening local tissue damage and causing systemic infection. Antivenoms are not effective to treat wound infections following SBE. Moreover, in several rural clinical settings, broad-spectrum antibiotics are often used without clear guidelines or based on limited laboratory data, resulting in undesirable side effects and exacerbated treatment costs. Therefore, robust antibiotic strategies should be developed to tackle this critical issue. Currently, there is limited information available on the bacterial profiles of SBE-induced infections and antibiotic susceptibility. Hence, it is essential to improve the knowledge of bacterial profiles and their antibiotic sensitivity in SBE victims to develop better treatment strategies. This study aimed to address this issue by examining the bacterial profiles of SBE victims with a specific focus on Russell's viper envenomation. The most frequently found bacteria in the bites of SBE victims were Staphylococcus aureus, Klebsiella sp., Escherichia coli, and Pseudomonas aeruginosa. Linezolid, clindamycin, colistin, meropenem, and amikacin were some of the most effective antibiotics for commonly grown bacteria in SBE victims. Similarly, ciprofloxacin, ampicillin, amoxiclave, cefixime, and tetracyclin were the least effective antibiotics for common bacteria found in the wound swabs of SBE victims. These data provide robust guidance for infection management following SBE and offer useful insights to aid in designing effective treatment protocols for SBE with serious wound infections in rural areas where laboratory facilities may not be readily available.

Morphological and genomic characteristics of two novel actinomycetes, Ornithinimicrobium sufpigmenti sp. nov. and Ornithinimicrobium faecis sp. nov. isolated from bat faeces (Rousettus leschenaultia and Taphozous perforates)

Four Gram-staining-positive, aerobic, non-motile, circle-shaped bacteria were isolated from the faeces of bats (Rousettus leschenaultia and Taphozous perforates) collected from Guangxi autonomous region (E106°49'20″, N22°20'54″) and Yunnan province (E102°04'39″, N25°09'10″) of South China. Strains HY006^T and HY008 shared highly 16S rRNA gene sequence similarity to those of Ornithinimicrobium pratense W204^T (99.3%) and O. flavum CPCC 203535^T (97.3%), while the strains HY1745 and HY1793^T were closest to the type strains O. ciconiae H23M54^T (98.7%), O. cavernae CFH 30183^T (98.3%), and O. murale 01-Gi-040^T (98.1%). Furthermore, when compared to the other members of the genus Ornithinimicrobium, the digital DNA-DNA hybridization and average nucleotide identity values of the four novel strains were within the ranges of 19.6-33.7% and 70.6-87.4%, respectively, both of which were below the respective recommended cutoff values of 70.0% and 95-96%. Significantly, strain HY006^T was resistant to chloramphenicol and linezolid whereas strain HY1793^T was resistant to erythromycin, clindamycin (intermediately), and levofloxacin (intermediately). The main cellular fatty acids (>20.0%) of our isolates were iso-C_15:0 and iso-C_16:0. Strains HY006^T and HY1793^T contained ornithine as the diagnostic diamino acid, also along with the alanine, glycine and glutamic acid in their cell wall. Based on phylogenetic, chemotaxonomic and phenotypic analyses, these four strains could be classified as two novel species of the genus Ornithinimicrobium, for which the names Ornithinimicrobium sufpigmenti sp. nov. and Ornithinimicrobium faecis sp. nov. are proposed. The type strains are HY006^T (=CGMCC 1.16565^T =JCM 33397^T) and HY1793^T (=CGMCC 1.19143^T =JCM 34881^T), respectively.

Molecular characteristics and antibiotic resistance mechanisms of clindamycin-resistant Streptococcus agalactiae isolates in China

Streptococcus agalactiae (Group B Streptococcus, GBS) is a major cause of neonatal infections with high morbidity and mortality, and clindamycin is the main antibiotic used to treat GBS infections in patients allergic to penicillin. We aimed to analyse the antibiotic sensitivity, sequence types, serotypes, virulence factors, and antibiotic resistance mechanisms of clinically isolated clindamycin-resistant S. agalactiae and provide basic data for the treatment, prevention, and control of clinical infection of S. agalactiae. A total of 110 strains of clindamycin-resistant S. agalactiae were collected from two tertiary hospitals in Hebei, China. We performed antibiotic sensitivity tests for 11 antibiotics on these strains and whole-genome sequencing analysis. All the strains were susceptible to penicillin, ampicillin, linezolid, vancomycin, tigecycline, and quinupristin-dalfopristin. Resistance to erythromycin, levofloxacin, tetracycline, and chloramphenicol were also observed. Genome sequence analysis revealed that all strains belonged to 12 sequence types (STs) related to six cloning complexes (CCs), namely CC10, CC19, CC23, CC651, CC1, and CC17. Five serotypes were identified, including IA, IB, II, III, and V. The most prominent resistance genes were mreA (100%) and ermB (81.8%). Furthermore, cfb, cylE, pavA and the gene cluster related to the pili were 100% present in all strains, followed by lmb (95.5%) and srr1 (67.2%). This study found that clindamycin-resistant S. agalactiae showed polymorphisms in molecular types and serotypes. Furthermore, multiple virulence factor genes have been identified in their genomes.

Multidrug-resistant Staphylococcus aureus isolated from chicken nuggets sold at superstores in Mymensingh, Bangladesh

Objective

This study was conducted to determine the colony forming units (CFU) to isolate, identify, and antibiotic sensitivity of Staphylococcus aureus from chicken nuggets (CN).

Materials and Methods

Sixty CN samples from two brands were collected from different superstores in Mymensingh, Bangladesh. Uncooked, oven-cooked (OC), or gas stove-cooked (GSC) CN samples were inoculated onto mannitol salt agar and blood agar.

Results

The total staphylococcal count (TSC) for uncooked CN ranged from log 4.68 to log 5.11 CFU/gm. For OC CN, TSC ranged from log 3.29 to log 3.62 CFU/gm. For GSC CN, TSC ranged from log 3.09 to log 3.49 CFU/gm. Relative to uncooked CN, microwave oven-cooked and GSC samples significantly reduced the TSC of CN (p < 0.01). Using the polymerase chain reaction assay and standard biochemical testing, only 8 out of 60 CN samples contained S. aureus. Staphylococcus aureus were resistant to Ampicillin (100%), Amoxicillin (100%), Oxacillin (75%), Cefixime (87.5%), Doxycycline (75%), intermediately sensitive to Erythromycin (25%), Cephalexin (12.5%), Ciprofloxacin (25%), Gentamicin (12.5%), Doxycycline (12.5%) and sensitive to Oxacillin (25%), Azithromycin (100%), Erythromycin (75%) Cephalexin (87.5%), Cefixime (12.5%), Chloramphenicol (100%), Ciprofloxacin (75%), Gentamicin (87.5%), Doxycycline (12.5%), and Vancomycin (100%).

Conclusion

This study reports the first isolation and identification of S. aureus from CN in Bangladesh. GSC CN was better than OC and uncooked CN. Data also suggest that CN is contaminated with multidrug-resistant S. aureus, which poses a public health hazard.

Phage Resistance Evolution Induces the Sensitivity of Specific Antibiotics in Pseudomonas aeruginosa PAO1

Bacteria frequently encounter selection by both phages and antibiotics. However, our knowledge on the evolutionary interactions between phages and antibiotics are still limited. Here, we characterized a phage-resistant Pseudomonas aeruginosa variant PAO1-R1 that shows increased sensitivity to gentamicin and polymyxin B. Using whole genome sequencing, significant genome differences were observed between the reference P. aeruginosa PAO1 and PAO1-R1. Compared to PAO1, 64 gene-encoding proteins with nonsynonymous single nucleotide polymorphisms (SNPs) and 31 genes with insertion/deletion (indel) mutations were found in PAO1-R1. We observed a significant reduction in phage adsorption rate for both phage vB_Pae_QDWS and vB_Pae_W3 against PAO1-R1 and proposed that disruption of phage adsorption is likely the main cause for evolving resistance. Because the majority of spontaneous mutations are closely related to membrane components, alterations in the cell envelope may explain the antibiotic-sensitive phenotype of PAO1-R1. Collectively, we demonstrate that the evolution of phage resistance comes with fitness defects resulting in antibiotic sensitization. Our finding provides new insights into the evolutionary interactions between resistance to the phage and sensitivity to antibiotics, which may have implications for the future clinical use of steering in phage therapies. IMPORTANCE Bacteria frequently encounter the selection pressure from both antibiotics and lytic phages. Little is known about the evolutionary interactions between antibiotics and phages. Our study provides new insights into the trade-off mechanism between resistance to the phage and sensitivity to antibiotics. This evolutionary trade-off is not dependent on the outer membrane proteins (OMPs) of the multidrug efflux pumps. The disruption of phage adsorption that induced phage resistance and the changes in structure or composition of membranes are presumably one of the major causes for antibiotic sensitivity. Our finding may fill some gaps in the field of phage-host interplay and have implications for the future clinical use of steering in phage therapies.

Introducing First-Year Undergraduate Students the Fundamentals of Antibiotic Sensitivity Testing through a Combined Computer Simulation and Face-to-Face Laboratory Session

Determining the antibiotic sensitivity of disease-causing microorganisms is a fundamental process in a clinical microbiology laboratory. With the continued use of antibiotics, the emergence of antibiotic resistance has become a significant health issue. However, the principles and laboratory testing to determine antibiotic sensitivity are generally not taught to first-year undergraduate students. This is partly due to the limited time to cover the fundamental biology of microorganisms and the mechanism of action of antibiotics in an introductory course. We overcame these limitations by teaching first-year students the fundamental principles of antibiotic sensitivity using an online data generator/simulation. Using the Kirby-Bauer disk diffusion test, students replicated the effects of antibiotic dose on bacterial growth and determined the antimicrobial susceptibility testing of their allocated bacterium. After 2-3 weeks, the antimicrobial sensitivity testing was replicated in an authentic face-to-face laboratory setting over 2 days. The impact of the intervention on student learning was assessed using a written laboratory report and a short questionnaire containing Likert and free-text questions. Student self-reported understanding of the content rose significantly, with nearly all students passing the written assessment. The approach was found to be enjoyable and interactive and facilitated authentic learning in first-year students. This cohort of students will continue to use more advanced versions of this simulation in future years, allowing for the long-term benefits of this approach to be assessed.

Identification and Antibiotic Susceptibility of Eggerthella lenta in Bloodstream Infections

The identification and antibiotic susceptibility of two clinical isolates of Eggerthella lenta from bloodstream infections were determined. This microorganism is rarely pathogenic, and the findings are presented here to promote the detection and awareness of this infection. The bacteria were obtained from one patient with pressure sores and another with a malignant gastric tumor. Smears were prepared, stained, and examined by microscopy. Single colonies were analyzed by Gram staining, MALDI-TOF MS, and the 16S rRNA gene sequencing. Antibiotic sensitivity was assessed by the agar dilution method. The bacilli were found to be Gram-positive, and the MS results showed 99.8% homology with E. lenta. It was confirmed by gene sequencing. Antibiotic susceptibility tests demonstrated that E. lenta was sensitive to piperacillin-tazobactam, ampicillin-sulbactam, imipenem, meropenem, metronidazole, clindamycin, and vancomycin. This study could increase awareness of this rare infection.

Ten-Year Analysis of Pathogenic Factors and Etiological Characteristics of Endophthalmitis from a Tertiary Eye Center in North China

Purpose

To describe the etiology and spectrum of isolated pathogens in endophthalmitis over 10 years from an ophthalmic hospital in North China and report their antimicrobial susceptibilities.

Patients and Methods

The data covered the patients with endophthalmitis treated at Qingdao Eye Hospital from January 2011 to December 2020. Patients’ medical history, pathogenic factors, bacterial and fungal culture results of intraocular specimens, and in vitro drug sensitivity test results were assessed.

Results

A total of 524 cases were counted in this study. Exogenous endophthalmitis was the main component, accounting for 94.66%, of which 49.62% of eyes had a history of ophthalmic trauma, intraocular surgery in 26.72% and suppurative keratitis in 17.37%. By comparison, endogenous endophthalmitis was found in only 5.34% of eyes. Among the 292 strains of pathogenic organisms obtained by co-culture, gram-positive bacteria accounted for 64.04%, with Staphylococcus epidermidis as the predominant pathogen (29.45%). Gram-positive cocci were identified in 76.77% of eyes with traumatic endophthalmitis, while 53.70% of keratitis-associated endophthalmitis was caused by fungi. The high susceptibility of bacteria to vancomycin (77.78%~98.33%) supported its continued use as empirical treatment. Among the fluoroquinolones, gram-positive cocci showed a higher susceptibility to gatifloxacin (94.83%), while there was a significant decrease to levofloxacin (51.67%). Gram-negative bacteria were less sensitive to cephalosporins (45.95%~66.67%) than fluoroquinolones (68.42%~78.05%) and aminoglycosides (75.00%~78.05%). Fungal susceptibilities to voriconazole and amphotericin B were 90.16% and 70.31% respectively. More than half of the 11 antibiotics were observed to exhibit a trend of reduced susceptibility.

Conclusion

Ophthalmic trauma was the primary pathogenic factor of endophthalmitis. Gram-positive cocci were the most common pathogens of traumatic and postoperative endophthalmitis, while suppurative keratitis-associated endophthalmitis often resulted from fungal pathogens. Levofloxacin as the preferred antibiotic in the perioperative period and cephalosporin as the first-line drug for the treatment of empiric endophthalmitis need to be vigilant.

Transposon mutagenesis in Mycobacterium abscessus identifies an essential penicillin-binding protein involved in septal peptidoglycan synthesis and antibiotic sensitivity

Mycobacterium abscessus (Mab) is a rapidly growing non-tuberculous mycobacterium (NTM) that causes a wide range of infections. Treatment of Mab infections is difficult because the bacterium is intrinsically resistant to many classes of antibiotics. Developing new and effective treatments against Mab requires a better understanding of the unique vulnerabilities that can be targeted for future drug development. To achieve this, we identified essential genes in Mab by conducting transposon sequencing (TnSeq) on the reference Mab strain ATCC 19977. We generated ~51,000 unique transposon mutants and used this high-density library to identify 362 essential genes for in vitro growth. To investigate species-specific vulnerabilities in Mab, we further characterized MAB_3167c, a predicted penicillin-binding protein and hypothetical lipoprotein (PBP-lipo) that is essential in Mab and non-essential in Mycobacterium tuberculosis (Mtb). We found that PBP-lipo primarily localizes to the subpolar region and later to the septum as cells prepare to divide. Depletion of Mab PBP-lipo causes cells to elongate, develop ectopic branches, and form multiple septa. Knockdown of PBP-lipo along with PbpB, DacB1, and a carboxypeptidase, MAB_0519 lead to synergistic growth arrest. In contrast, these genetic interactions were absent in the Mtb model organism, Mycobacterium smegmatis, indicating that the PBP-lipo homologs in the two species exist in distinct genetic networks. Finally, repressing PBP-lipo sensitized the reference strain and 11 Mab clinical isolates to several classes of antibiotics, including the β-lactams, ampicillin, and amoxicillin by greater than 128-fold. Altogether, this study presents PBP-lipo as a key enzyme to study Mab-specific processes in cell wall synthesis and importantly positions PBP-lipo as an attractive drug target to treat Mab infections.

Pathology and Prevalence of Antibiotic-Resistant Bacteria: A Study of 398 Pet Reptiles

Reptiles are potential reservoirs of bacteria that could be transmitted, thus becoming a zoonotic hazard. (1) Background: This three-year investigation surveyed the pathological status of 398 pet reptiles: chelonians, snakes (venomous/non-venomous), and lizards. The main pathological entities found were related to the skin, the sensory organs, the digestive system, the respiratory system, the cardiovascular system, the urinary system, the genitalia, the osteo−muscular tract, surgical issues, tumors, and intoxications. (2) Methods: In 25 individuals treated with antibiotics, no clinical healing was recorded, for this reason, an antimicrobial resistance profile analysis of the 43 samples gathered was processed. An antibiogram was performed using the VITEK®2 ID-GP (bio-Mérieux, Marcy l’Etoile, France) automated platform, with 22 bacterial strains being isolated. (3) Results: The statistics (ANOVA) revealed that the most common disease category was diseases of the digestive system, followed by diseases of the skin, respiratory system, nervous system, and reproductive system. A significant correlation (p < 0.01) between disease incidence and reptile species was reported, with correlations found between all species and diseases diagnosed. The most common bacteria isolated were Enterococcus faecalis, Pseudomonas aeruginosa, Stenotrophomas (Xanthomonas) maltophilia, Escherichia coli, Klebsiella oxytoca, and Salmonella spp., but Beta-hemolytic Streptococcus, Staphylococcus aureus, Citrobacter spp., and Proteus spp. were also identified. (4) Conclusions: These microorganisms revealed degrees of resistance against penicillins, cephalosporins, macrolides, lincosamides, aminoglycosides, and tetracyclines. The animals can be categorized according to their sensitivity to diseases in the following order (most sensitive to least sensitive): chelonians, venomous snakes, non-venomous snakes, and lizards.

[Knockout of ribosomal genes bS22 and bL37 increases the sensitivity of mycobacteria to antibiotics]

In recent years, two novel proteins in the ribosomes of mycobacteria have been discovered by cryo-electron microscopy. The protein bS22 is located near the decoding center of the 30S subunit, and the protein bL37 is located near the peptidyl transferase center of the 50S subunit. Since these two proteins bind to conserved regions of the ribosome targeted by antibiotics, it is speculated that they might affect the binding of related drugs to these targets. Therefore, we knocked out the genes encoding these two proteins in wild-type Mycolicibacterium smegmatis mc²155 through homologous recombination, and then determined the growth curves of these mutants and their sensitivity to related antibiotics. The results showed that compared with the wild-type strain, the growth rate of these two mutants did not change significantly. However, mutant ΔbS22 showed increased sensitivity to capreomycin, kanamycin, amikacin, streptomycin, gentamicin, paromomycin, and hygromycin B, while mutant ΔbL37 showed increased sensitivity to linezolid. These changes in antibiotics sensitivity were restored by gene complementation. This study hints at the possibility of using ribosomal proteins bS22 and bL37 as targets for drug design.

Treatment of Hospital-Acquired Infections in Patients with Cirrhosis - New Challenges

Background

Hospital acquired infections (HAI) in the cirrhotic patients contribute to hepatic decompensation. With emergence of bacterial drug resistance, designing the treatment protocol of HA infection has become the foremost challenge.

Purpose

To analyze the resistance pattern of organisms isolated from hospital-acquired (HA) infections and determine appropriate antibiotics treatment protocols for these infections.

Study Design

A prospective hospital based observational study was undertaken.

Patients and Methods

The present study was conducted over 18 months at Kasturba Medical College, Mangalore, Karnataka, India. Patients with suspected HA infections were subjected to clinical, hematological and microbiological evaluation. Antibiotic sensitivity evaluation was undertaken for the bacteria isolated from these patients.

Results

During the study period, 398 patients with cirrhosis were 472 times admitted to the hospital for treatment. Out of these patients, 40 patients were diagnosed with 50 HA infections. Fifty five different organisms were isolated from these infections. It was found that these 55 bacteria isolates comprised 30 (54.54%) gram-negative (GN) and 25 (45.45%) gram-positive (GP) bacteria. Quite seriously, extended-spectrum beta-lactamase (ESBL) producers and methicillin-resistant Staphylococcus aureus (MRSA) were detected in 40% and 58% of GN and GP infections respectively. A total of 36 (65.4%) and (14.5%) 8 out of 55 isolated organisms exhibited multi–drug resistance (MDR) and extensive drug resistance (XDR) behavior, respectively.

Conclusion

Cirrhosis patients with HA infection possess higher prevalence of MDR and XDR infections. In such sick patients, cephalosporin and quinolones are not the appropriate empirical antibiotics. Herein, we propose a tigecycline with carbapenem like meropenem and vancomycin based empirical antibiotics protocol to be prescribed for such patients. De-escalation is advised after the culture sensitivity report is obtained.

Evaluation of the BioFire FilmArray Pneumonia Panel Plus to the Conventional Diagnostic Methods in Determining the Microbiological Etiology of Hospital-Acquired Pneumonia

Hospital-acquired pneumonia (HAP) is a substantial public health issue that is associated with high mortality rates and is complicated by an arsenal of microbial etiologies, expressing multidrug-resistant phenotypes, rendering relatively limited therapeutic options. BioFire FilmArray Pneumonia Panel plus (BFPP) is a simple multiplexed PCR system that integrates sample preparation, nucleic acid extraction, amplification, and analysis of microbial etiology, with a turnaround time of about one hour. In comparison to standard culture methods, BFPP is simpler, easier to perform, and can simultaneously detect the most common pathogens involved in lower respiratory tract infections (34 targets). Accordingly, we evaluated the diagnostic performance of the multiplexed BFPP for the rapid detection of 27 clinically relevant respiratory pathogens and 7 genetic markers among 50 HAP cases admitted to the intensive care unit (ICU), who submitted mini-bronchoalveolar (mBAL) specimens. In comparison to standard culture methods, BFPP showed an overall sensitivity of 100% [95% CI; 90-100] and overall specificity of 90% [95% CI; 87.4-92.5] among all the tested bacterial targets. BFPP identified 11 viral targets (22%) among the tested specimens. The BFPP semi-quantitative analysis showed a concordance rate of 47.4% among positive culture specimens. For the investigation of the antibiotic resistance genes, BFPP showed a positive percent agreement (PPA), a negative percent agreement (NPA), and an overall percent agreement (OPA), reaching 97% [95% CI; 90-100], 95% [95% CI; 91.5-97], and 95% [95% CI; 93-97], respectively, with standard antibiotic sensitivity testing. In conclusion, BFPP has the potential to enhance the rapid microbiological diagnosis of HAP cases, and could aid in tailoring appropriate antibiotic therapies.

Characterization of Vibrio spp. in environmental water samples collected from flood prone areas of Bangladesh and their antibiotic resistance profile

Last cholera epidemic has been recorded in Bangladesh between 1992-1993, while few sporadic localized outbreaks have been reported as recent as 2005. Serotype O1 of Vibrio cholera is considered as the principal causative agent which transmits through contaminated drinking water resulting that epidemic. Therefore, the objective of this research was to isolate V. cholera in 3 different water sources; River, pond and tube-well, in 5 different locations of Gazipur, Bangladesh, and to analyze their antibiogram study. A total of 45 water samples were randomly collected for the isolation and identification of Vibrio spp. Samples are then serially diluted in alkaline peptone water and streak on Thiosulfate Citrate Bile Salt Sucrose-TCBS agar for quantification of V. spp. For V. cholera isolation water samples were first enriched in nutrient broth at 37 °C for 16 hours followed by cultivation in selective media; TCBS agar at 37 °C for 24 hours. Yellow colonies on TCBS agar were screed as V. cholera and was confirmed by analyzing their biochemical characteristics like Catalase, Oxidase, MR, VP, Indole, Sugar fermentation. Following isolation antibiotic sensitivity test was performed on each V. cholera isolates to determine their antibiotic sensitivity profile. The results showed, out of 45 samples 12 contained V. cholera. Tube-well water has significantly lower concentration (log CFU/mL) of V. spp. than river and pond water (P < 0.05). Bacterial concentration doesn't deviate (P > 0.05) significantly in 5 different location the sample was collected from. All the 12 isolates were sensitive to Gentamicin and ciprofloxacin (100%), while Chloramphenicol (91.67%), Sulfamethoxazole (91.67%), Azithromycin (66.67%) showed high sensitivity. Isolates showed marginal sensitivity towards Tetracycline (33.33%), and Cephalexin (16.67%) and 100% resistance against antibiotics like Vancomycin, Penicillin, Erythromycin, and Nalidixic Acid. Based on these data we recommend using tube-well water instead of river and pond water for drinking purposes. Furthermore, we suggest selective use of sensitive antimicrobials listed here for therapeutics of cholera outbreak.

Common Bacterial Isolates Associated With Neonatal Sepsis and Their Antimicrobial Profile: A Retrospective Study at King Abdulaziz University Hospital, Jeddah, Saudi Arabia

Background

Neonatal sepsis is a major contributor to morbidity and mortality among neonates. There has been considerable geographic variation in causative pathogens and antimicrobial sensitivity profiles over time. This makes the continuous monitoring of patterns of emergence crucial for the effective implementation of antimicrobial therapy guidelines in an attempt to control antimicrobial resistance.

Methods

A retrospective study was conducted among neonates with sepsis admitted to King Abdulaziz University Hospital, Jeddah, Saudi Arabia, between May 2011 and October 2018. The data were collected from medical records in the neonatal intensive care unit and analyzed using SPSS version 20 (IBM Corp., Armonk, NY).

Results

There were 246 neonates clinically diagnosed with sepsis, of whom 40 (16.26%) had positive blood cultures. In the blood cultures, coagulase-negative Staphylococcus was the most prevalent microorganism (57.5%), followed by Klebsiella spp. (10%). Streptococcus agalactiae, Enterobacter cloacae, Escherichia coli, Acinetobacter baumanii, and Candida spp. each accounted for 5% of all isolates. Only single isolates of methicillin-resistant Staphylococcus aureus, Pseudomonas aeruginosa, and Bacillus spp. (2.5% each) were detected in this study. Most of the isolated microorganisms exhibited high sensitivity to ampicillin and gentamicin.

Conclusions

This study points to a likely emergence of coagulase-negative Staphylococci as the main cause of sepsis among neonates. Ampicillin and gentamicin are highly effective against the commonly isolated bacterial pathogens that cause neonatal sepsis.

Evaluation of the current bacteriological profile and antibiotic sensitivity pattern in chronic suppurative otitis media

OBJECTIVE

To determine the current microbiological profile of chronic suppurative otitis media (CSOM), their antimicrobial sensitivity, their resistance pattern to locally available antibiotics and the appropriate antibiotic against isolated microorganisms causing CSOM.

METHODS

This cross-sectional study involved 91 ear swab specimens obtained from patients clinically diagnosed with active CSOM. Swabs were cultured for microbial identification according to a standard protocol. We performed antibiotic susceptibility testing, using the modified Kirby-Bauer disc diffusion method, and the diameter of the inhibition zone was interpreted based Clinical Laboratory Standards Institute guidelines.

RESULTS

Microbial growth was seen in 85 (93.4%) samples, but 6 (6.6%) samples had no growth. Among the samples with growth, 63 (69.2%) were monomicrobial, 13 (14.3%) were polymicrobial, and 9 (9.9%) were of mixed growth with more than three microorganisms. The most common bacteria isolated was Pseudomonas aeruginosa (32.6%) followed by Staphylococcus aureus (16.9%) and Klebsiella spp. (5.6%). The most sensitive antibiotics against P aeruginosa were ceftazidime, meropenem, piperacillin-tazobactam, and cefepime. S aureus showed the highest sensitivity toward rifampin, cefoxitin, and fusidic acid.

CONCLUSIONS

The bacteriological profile of CSOM showed a high prevalence of P aeruginosa, followed by S aureus and Klebsiella spp. with different distributions in different age groups. We observed a declining pattern of their antibiotic sensitivity. It is important to be aware of the current trend of the bacteriological profiles and to revise the antibiotic regime according to both the sensitivity and age groups.Level of Evidence: NA.

A cross-sectional study of etiological and sensitivity profiling of meningitis in under-five children

Objectives

The study aimed to understand the organism spectrum and antibiotic sensitivity profile of acute bacterial meningitis in pediatric population.

Methods

A cross-sectional study was conducted at the department of microbiology of a tertiary care center for a period of 18 months. Suspected cases of meningitis between 1 and 60 months of age were considered for the study. All cases underwent cerebrospinal fluid tap for direct microscopy (DM), Gram staining, and culture sensitivity.

Results

The mean age of the study patients was 10.42 months, with 61.7% of males and 38.3% of females. DM and culture were positive in 22.90% and 28.00% of the patients, respectively. On Gram stain, there were 29 (59.18%) cases of Gram positivity and 20 (40.82%) cases of Gram negativity. The culture growth showed that Acinetobacter spp. was isolated in 15 (30.6%) of the cases. Enterococcus spp. was isolated in 9 (18.4%) of the cases. Klebsiella pneumoniae was isolated in 8 (16.3%) of the cases. Staphylococcus aureus was isolated in 8 (16.3%) of the cases. Enterobacter spp. was isolated in 3 (6.12%) of the cases. Pseudomonas aeruginosa was isolated in 3 (6.12%) of the cases. Streptococcus pneumoniae was isolated in 3 (6.1%) of the cases. The antibiogram of different agents showed wide variation, with colistin being 100% sensitive for Acinetobacter, Enterobacter, K. pneumoniae, and P. aeruginosa.

Conclusion

The present study revealed that Acinetobacter, Enterococcus, K. pneumoniae, and S. aureus were the most common bacterial etiologic agents of ABM. The 100% antibiotic sensitivity of the organisms to some antibiotics may suggest the use of such antibiotics while awaiting for culture sensitivity reports.

Corynebacterium spp. - problematic pathogens of the human respiratory tract (review of literature)

Corynebacterium spp. - representatives of the normal microflora of the human body, but their role in the development of diseases in both immunocompromised and immunocompetent patients is known. Corynebacterim spp. (C. pseudodiphtheriticum, C. striatum, C. amycolatum, C. accolens, C. argentoratense, etc.) is associated with diseases of the respiratory tract: tracheitis, pharyngitis, rhinosinusitis, bronchitis, etc. They can be transmitted by airborne droplets, household contact, and possibly by hematogenic pathways. Corynebacterim spp. toxins do not produce, but are capable of adhesion and invasion, biofilm formation, production of neuraminidase, hyaluronidase, and hemolysin. It is necessary to take into account not so much the species, but the strain affiliation of isolates of Corynebacterium spp., since among the representatives of one species of non-diphtheria corynebacteria (for example, C. pseudodiphtheriticum), colonizing the respiratory tract, there may be strains that can exhibit not only pathogenic properties, but also probiotic activity. Microbiological diagnostics is based on their quantitative determination in biological material, phenotypic (culture study, test systems for biochemical identification, Vitek 2 automated systems) and genotypic (16SpRNA gene sequencing and rpoB) methods. It is possible to use mass spectrometric analysis (MALDI-ToF-MS). The greatest activity against Corynebacterium spp. in vitro studies preserve vancomycin, teicoplanin, and linezolid. Successful therapy with at least two of the following antimicrobial agents (AMP) has been reported: vancomycin, rifampicin, linezolid, and daptomycin. The sensitivity of isolates of Corynebacterium spp. to AMP is not related to the species, but is due to strain differences, and therefore it is necessary to test each isolated strain. Continuous monitoring of the sensitivity of Corynebacterium spp. strains to AMP is necessary due to the observed variability of these traits. Of particular importance is the identification of multidrug-resistant isolates that are currently considered highly pathogenic. When compiling the review, the databases Scopus, Web of Science, The Cochrane Library, CyberLeninka, RSCI were used.

Association Between Patients' Immunoglobulin E Levels and Difficulty Eradicating Helicobacter pylori

Background

Helicobacter pylori is a cause of gastric cancer, and thus the eradication of this bacterium is very important. The success rate of primary eradication has been dramatically increased by the introduction of potassium-competitive acid blockers. However, H. pylori cannot be eradicated in all patients, and the contributing factors need to be clarified.

Aim

Because allergy status may be a factor and considering research linking hay fever with eradication failure, the purpose of this study was to examine blood immunoglobulin E levels as a contributing factor in patients who were unable to eradicate H. pylori in a single eradication treatment and who underwent multiple eradication attempts.

Methods

Questionnaire data were collected from 250 patients who visited the Department of Gastroenterology, Hamamatsu University School of Medicine, for H. pylori eradication. In addition, non-specific IgE levels in the blood were measured and analyzed with one-way analysis of variance. Multinomial logistic regression analysis was performed to examine the association between the number of eradication attempts and the IgE level (< 500 vs ≥ 500 IU/mL).

Results

The mean IgE values were 188.4, 211.9, and 744.0 IU/mL in patients with one, two, and three or more eradication attempts, respectively (P < 0.05). The results of multinomial logistic regression analysis showed that attempting eradication three or more times was significantly associated with high levels of IgE, even after consideration of antibiotic sensitivity.

Conclusion

H. pylori eradication was less likely in patients with high IgE. It is thus necessary to study the appropriate regimen for patients with high IgE levels.

Community-acquired bacteremia among HIV-infected and HIV-exposed uninfected children hospitalized with fever in Mozambique

Background:

Bacteremia is a major cause of morbidity and mortality worldwide. Children infected with HIV present with patterns of bacteremia generally associated with poor prognosis. In Mozambique, data on bacteremia are sparce.

Methods:

We conducted an observational study of HIV-infected and HIV-exposed uninfected children, aged 0–59 months, hospitalized with fever between April 1, 2016 and February 28, 2019. A single bacterial culture was collected at admission. Descriptive statistics were used to summarize microorganisms detected and antibiotic susceptibility testing.

Results:

A total of 808 HIV-infected (90%) and HIV-exposed uninfected (10%) children were enrolled. Blood culture positivity was 12% (95% CI: 9.9%–14.4%). Five organisms accounted for most cases: Staphylococcus Aureus (37%), Klebsiella spp (11%), Salmonella spp (11%), Escherichia Coli (9%) and Micrococcus (7%). Antibiotic resistance was common. Nearly 70% of Staphylococcus Aureus were methicillin-resistant and roughly 50% of Klebsiella had ESBL production.

Conclusion:

Community-acquired bacteremia was common in HIV-infected and HIV-exposed uninfected children hospitalized in Mozambique with a febrile illness. High rates of MRSA and ESBL producing organisms has implications for empiric antibiotics utilized in Mozambique. Longitudinal data on the prevalence and antimicrobial resistance patterns of important pathogens are badly needed to guide policy for drug formulary expansion and antibiotic prescription guidelines.

Community-acquired Acinetobacter calcoaceticus pneumonia in a patient with agammaglobulinaemia

We herein describe the case of a 38-year-old patient with congenital agammaglobulinemia who presented with community-acquired pneumonia; acute respiratory failure with sepsis ensued requiring ICU admission, mechanical ventilation and vasopressors administration. The causative organism was identified as Acinetobacter calcoaceticus, sensitive to multiple agents. Stewardship was effectively applied; clinical, biologic and radiologic improvement resulted, and the patient was later discharged on ciprofloxacin therapy; improvement being maintained thereafter. This is the first reported case of community-acquired Acinetobacter pneumonia in our region.

Nonsteroidal antiinflammatory drugs alter antibiotic susceptibility and expression of virulence-related genes and protein A of Staphylococcus aureus

Background/aim

Nonsteroidal antiinflammatory drugs (NSAIDs) including diclofenac, naproxen, ibuprofen, acetylsalicylic acid, and acetaminophen have been shown to have antimicrobial effects on various microorganisms. The aim of this study was to investigate the antibacterial effects of NSAIDs on Staphylococcus aureus .

Materials and methods

Susceptibilities of S. aureus strains to NSAIDs with or without antimicrobials (moxifloxacin, vancomycin, ciprofloxacin, clindamycin, and gentamicin) were determined using the microdilution method and disk diffusion test. Expression levels of genes in the presence of drugs were investigated by real-time quantitative RT-PCR (qRT-PCR), and immunoblotting analysis was performed for staphylococcal protein A (SpA).

Results

Our results showed that all NSAIDs were active against S. aureus strains with MIC values ranging from 195 µg/mL to 6250 µg/mL. NSAIDs increased the antibiotic susceptibility of the strains, and diclofenac was found to be more effective than the other drugs. Drugs showed different effects on expression levels of virulence factor and/or regulatory genes. Immunoblotting analysis of SpA protein was mostly in accordance with qRT-PCR results.

Conclusion

The regulatory/virulence factor genes and proteins of S. aureus investigated in this study may be reasonable targets for these drugs, and we suggest that the data may contribute to the field of infection control and antimicrobial resistance.

Trends of Prosthetic Joint Infection Organisms and Recurrence for a Single High-Volume Arthroplasty Surgeon Over 20 Years

BACKGROUND

Prosthetic joint infection (PJI) is a morbid complication following total joint arthroplasty (TJA). PJI diagnosis and treatment has changed over time, and patient co-management with a high-volume musculoskeletal infectious disease (MSK ID) specialist has been implemented at our institution in the last decade.

METHODS

We retrospectively evaluated all consecutive TJA patients treated for PJI between 1995 and 2018 by a single high-volume revision TJA surgeon. Microbial identities, antibiotic resistance, prior PJI, and MSK ID consultation were investigated.

RESULTS

In total, 261 PJI patients (median age 66 years, interquartile range 57-75) were treated. One-year and 5-year reinfection rates were 15.8% (95% confidence interval [CI] 11.6-20.7) and 22.1% (95% CI 17.0-27.7), respectively. Microbial identities and antibiotic resistances did not change significantly over time. Despite seeing more prior PJI patients (53.3% vs 37.6%, P = .012), MSK ID-managed patients had similar infection rates as non-MSK ID-managed patients (hazard ratio [HR] 1.02, 95% CI 0.6-1.75, P = .93). Prior PJI was associated with higher reinfection risk (HR 2.39, 95% CI 1.39-4.12, P = .002) overall and in patients without MSK ID consultation, specifically (HR 2.78, 95% CI 1.37-5.65, P = .005). This risk was somewhat lower and did not reach significance in prior PJI patients with MSK ID consultation (HR 1.97, 95% CI 0.87-4.48, P = .106).

CONCLUSION

We noted minimal differences in microbial/antibiotic resistances for PJI over 20 years in a single institution, suggesting current standards of PJI treatment remain encouragingly valid in most cases. MSK ID involvement was not associated with lower reinfection risk overall; however, in patients with prior PJI, the risk of reinfection appeared to be somewhat lower with MSK ID involvement.

LEVEL OF EVIDENCE

Level IV-Case Series.

An unusual case of sepsis due to Salmonella enterica serovar Weltevreden, an emerging pathogen of non-typhoidal salmonellosis

Salmonella enterica serovar Weltevreden is identified as an emerging pathogen, especially in the South and Southeast Asian regions. A 45-year-old male presented with an acute febrile illness, disoriented and confused. Blood culture became positive for Salmonellae enterica serovar Weltevreden. The patient was started on intravenous Ceftriaxone. Despite aggressive management, he developed acute respiratory distress syndrome with septic shock, which required intubation and mechanical ventilation. On the 11th day of admission, he succumbed due to sepsis from peritonitis with bowel infarction. Severe sepsis due to S. Weltevreden is rare. Diabetes, malignancy, therapeutic immune suppression may predispose to invasive disease. Biochemical similarities to other Salmonella species may lead to S. Weltevreden being overlooked by clinicians. Isolates from around the world remain sensitive to most freely available antibiotics. Emergence of resistance to common antimicrobial agents could pose an obvious public health threat.

Evolution, Clinical and Microbiological Characteristics of Invasive Pneumococcal Disease since the Introduction of the Pneumococcal Conjugate Vaccine 13-Valent in Adults over 18 Years Old

Invasive pneumococcal disease (IPD) presents high mortality in the population at risk. The aim of this work is to know the evolution, clinical and microbiological characteristics of IPD in the adult population of Majorca, since the introduction of a public funded program for pneumococcal conjugate vaccine (PCV-13) in the pediatric population in the Balearic Islands in 2016. For this purpose, a retrospective multicenter study was carried out in which all episodes of IPD in adult patients from the four hospitals of the public health system of Majorca were included, comparing the periods between 2012 and 2015 and between 2016 and 2019. Clinical variables, serotypes and antibiotic sensitivity were collected. There were 498 cases of IPD; 56.8% were male with a mean age of 67 (standard deviation: 16). Most infections were bacterial pneumonias (73.7%). Of the total cases, 264 (53%) presented complications. Of the 498 cases, 351 strains were obtained, of which 145 (41.3%) belong to vaccinal serotypes (included in the PCV-13 vaccine) and 206 (58.7%) to non-vaccinal serotypes (not included in the PCV-13 vaccine). The percentage of IPD caused by vaccinal serotypes was lower in the second period (47.8% vs. 34.5%; p = 0.012).

Microbiological profile of urinary tract infections in a tertiary medical facility in Western Mexico: An update

Urinary tract infections (UTIs) are one of the most important issues in modern medicine. In developing countries, the use of antibiotics is a common practice, and due to this, antibiotic resistance has increased. The objective of this research was to update and report on the microbiological profile of urinary tract infections based on the number of positive urine cultures (UCs), resistance, sensitivity, and the prevalence of bacterial strains. The results were obtained from the database of a tertiary medical facility in Western Mexico. The number of positive UCs was 1769 from inpatients and outpatients who were users of medical services in the hospital from January to December of 2017. The most commonly isolated microorganism was E. coli, with 1225 cases, of which 603 (49.2%) were ESBL (Extended-Spectrum Beta-Lactamase-producing bacteria) strains. The resistance rate of nitrofurantoin was 36.6%, and meropenem showed the most promising results with a resistance rate of only 7.1%. Resistances to quinolones and cephalosporins among the isolates investigated were 51%-67%. Based on our results, it is necessary to increase controls and to improve management protocols in order to achieve better medical practices by reducing antibiotic resistance.

Antibiotic susceptibility and pathogenicity of Aeromonas hydrophila isolated from red hybrid tilapia (Oreochromis niloticus×Oreochromis mossambicus) in Malaysia

Background and Aim:

Aeromonas hydrophila is a major cause of bacterial infections affecting a wide range of warm water fishes worldwide. In Malaysia, A. hydrophila isolations from diseased fishes were previously reported; however, with limited information. The present study investigates the antibiotic susceptibility and pathogenicity of A. hydrophila isolated from farmed red hybrid tilapia (Oreochromis spp.) in Malaysia.

Materials and Methods:

A. hydrophila was biochemically identified and subjected to antibiotic susceptibility tests. The isolate was then intraperitoneally injected into red hybrid tilapia, and the mortality, clinicopathological changes, and LD₅₀ were determined up to 240 h post-infection (hpi).

Results:

The isolate demonstrated multiple antibiotic resistances (MAR) toward amikacin, ampicillin, cefotaxime, amoxicillin, trimethoprim-sulfamethoxazole, erythromycin, and streptomycin, with a MAR index of 0.5. The experimental infection of A. hydrophila at 10⁵ CFU/mL in the red hybrid tilapia resulted in 100% mortality at 240 hpi. The LD₅₀ was determined at 1.1×10⁴ CFU/mL. Infected fish demonstrated occasional erratic swimming patterns, localized hemorrhages and depigmentation on the body and operculum areas, fin erosion, enlargement of the gall bladder, and hemorrhage in internal organs. Microscopic observation of infected fish revealed brain congestion, tubular necrosis, and glomerular shrinkage in the kidneys, necrosis of hepatocytes, and congestion of blood vessels in the liver.

Conclusion:

The high virulence of A. hydrophila to the red hybrid tilapia emphasizes the importance of active, on-going monitoring of its prevalence in Malaysian tilapia farming.

Antibiofilm Activity of Lactobacillus plantarum 12 Exopolysaccharides against Shigella flexneri

In developing countries, Shigella flexneri is the most common enteric pathogen causing bacillary dysentery. Biofilm formation by S. flexneri can cause the emergence of antibiotic-resistant strains, which poses serious threats to food safety and human health. In this study, the effects of Lactobacillus plantarum 12 exopolysaccharides (L-EPSs) and S. flexneri exopolysaccharides (S-EPSs) on S. flexneri CMCC51574 biofilm formation were investigated. The results showed that L-EPS could decrease polysaccharide production in the extracellular polymeric matrix of S. flexneri and inhibit biofilm formation by S. flexneri L-EPS could decrease the minimum biofilm elimination concentration (MBEC) of antibiotics against S. flexneri biofilm and inhibit S. flexneri adhesion to and invasion into HT-29 cell monolayers, which might be ascribed to S. flexneri biofilm disturbance by L-EPS. In contrast, S-EPS exhibited the opposite effects compared to L-EPS. The monosaccharide composition analysis showed that L-EPS was composed of mannose, glucuronic acid, galactosamine, glucose, galactose, and xylose, with the molar ratio of 32.26:0.99:1.79:5.63:0.05:4.07, while S-EPS was composed of mannose, glucuronic acid, galactosamine, glucose, and galactose, with the molar ratio of 25.43:2.28:7.13:5.35. L-EPS was separated into the neutral polysaccharide L-EPS 1-1 and the acidic polysaccharide L-EPS 2-1 by ion-exchange chromatography and gel chromatography. L-EPS 2-1 exerted higher antibiofilm activity than L-EPS 1-1. The antibiofilm activity of L-EPS might be associated with its structure.IMPORTANCES. flexneri is a widespread foodborne pathogen causing food contamination and responsible for food poisoning outbreaks related to various foods in developing countries. Not only has biofilm formation by S. flexneri been difficult to eliminate, but it has also increased the drug resistance of the strain. In the present study, it was demonstrated that L-EPSs secreted by Lactobacillus plantrum 12 could inhibit S. flexneri biofilm formation on, adhesion to, and invasion into HT-29 cells. Also, L-EPSs could decrease the minimum biofilm elimination concentration (MBEC) of the antibiotics used against S. flexneri biofilm. Therefore, L-EPSs were shown to be bioactive macromolecules with the potential ability to act against S. flexneri infections.

Characterization of aerobic vaginitis in late pregnancy in a Chinese population: A STROBE-compliant study

This study aimed to analyze the clinical characteristics, responsible pathogens, and antibiotic sensitivity of aerobic vaginitis (AV) infection in women in late pregnancy in western China.We enrolled 246 pregnancy with AV (≥35 weeks gestation) and 204 reproductive non-pregnancy with AV from West China between January 2019 and December 2019. Then, bacterial culture, identification and antibiotic sensitivity testing were performed. Subsequently, we retrospectively analyzed the vaginal microbiota of 250 healthy pregnant women with no AV and compared the maternal features and pregnancy outcomes.Regarding bacterial diversity, Streptococcus and Lactobacillus were highly abundant in women with AV in late pregnancy, whereas Staphylococcus spp. and other bacteria were significantly more abundant in reproductive non-pregnant women with AV. In addition, 82.5% (343/416) of the single isolate comprised Escherichia coli, group B Streptococcus, Enterococcus faecalis, and Staphylococcus aureus. Among the top 4 isolates, 13.4% (46/343) were multidrug-resistant, but all isolates were highly susceptible to nitrofurantoin. Escherichia coli was 100% susceptible to amikacin, meropenem, ertapenem, and imipenem (100%, 157/157), and gram-positive cocci were 100% (186/186) susceptible to vancomycin and linezolid. Finally, we found that pregnant women with AV had high rates of histories of vaginitis, premature rupture of membranes and neonatal infection.Our study reveals new insights into AV infection during pregnancy and highlights the different vaginal bacterial microbiome compositions between pregnant and reproductive non pregnant women with AV, these results may translate to treatments that are more cost-effective than current standard treatments.

Clostridioides difficile Senses and Hijacks Host Heme for Incorporation into an Oxidative Stress Defense System

Clostridioides difficile infection of the colon leads to severe inflammation and damage to the gastrointestinal epithelium due to the production of potent toxins. This inflammatory tissue damage causes the liberation of high concentrations of host heme at infection sites. Here, we identify the C. difficile heme-sensing membrane protein system (HsmRA) and show that this operon induces a protective response that repurposes heme to counteract antimicrobial oxidative stress responses. HsmR senses vertebrate heme, leading to increased expression of the hsmRA operon and subsequent deployment of HsmA to capture heme and reduce redox damage caused by inflammatory mediators of protection and antibiotic therapy. Strains with inactivated hsmR or hsmA have increased sensitivity to redox-active compounds and reduced colonization persistence in a murine model of relapse C. difficile infection. These results define a mechanism exploited by C. difficile to repurpose toxic heme within the inflamed gut as a shield against antimicrobial compounds.

Two cases of septic shock with different outcomes caused by non-O1/non-O139 Vibrio cholerae isolates

In recent decades, increasing numbers of human infections have been linked to non-O1/non-O139 Vibrio cholerae. Septicemia resulting from non-O1/non-O139 V. cholerae infection is rare but has high mortality. The pathogenesis of non-O1/non-O139 V. cholerae septicemia is poorly understood. Here, we report two sporadic cases of septicemia following non-O1/non-O139 V. cholerae infection from an inland area of China. Patient 1 died rapidly within 24 hours, while patient 2 gradually recovered from septic shock. To explore the reasons for these divergent outcomes, we compared the two cases, tested the antibiotic sensitivity of the two isolates, and investigated their virulence genes and sequence types.

Chimeric Phage Nanoparticles for Rapid Characterization of Bacterial Pathogens: Detection in Complex Biological Samples and Determination of Antibiotic Sensitivity

Rapid, specific, and sensitive detection of pathogenic bacteria in drink, food, and clinical samples is an important goal for public health. In addition, rapid characterization of antibiotic susceptibility could inform clinical choices and improve antibiotic stewardship. We previously reported a straightforward, inexpensive strategy to detect Gram-negative bacterial pathogens, including Pseudomonas aeruginosa, Vibrio cholerae, and Escherichia coli, taking advantage of the high affinity and specificity of phages for their bacterial hosts. Chimeric phages targeted different bacterial pathogens, and thiolation of the phages induced aggregation of gold nanoparticles (AuNPs), leading to a visible colorimetric response in the presence of at least ∼100 cells of the target bacteria. Here, we apply this strategy to complex biological samples (milk, urine, and swabs from a porcine ex vivo model of P. aeruginosa infection). We also show that this assay can be used to identify the antibiotic susceptibility profile based on detection of bacterial growth in the presence of different antibiotics. The prospect for using phage-conjugated AuNPs to detect bacterial pathogens in clinical samples and guide antibiotic choice is discussed.

High Prevalence of Macrolide-Resistant Bordetella pertussis and ptxP1 Genotype, Mainland China, 2014-2016

According to the government of China, reported cases of pertussis have increased remarkably and are still increasing. To determine the genetic relatedness of Bordetella pertussis strains, we compared multilocus variable-number tandem-repeat analysis (MLVA) results for isolates from China with those from Western countries. Among 335 isolates from China, the most common virulence-associated genotype was ptxA1/ptxC1/ptxP1/prn1/fim2–1/fim3A/tcfA2, which was more frequent among isolates from northern than southern China. Isolates of this genotype were highly resistant to erythromycin. We identified 36 ptxP3 strains mainly harboring ptxA1 and prn2 (35/36); ptxP3 strains were sensitive to erythromycin and were less frequently from northern China. For all isolates, the sulfamethoxazole/trimethoprim MIC was low, indicating that this drug should be recommended for patients infected with erythromycin-resistant B. pertussis. MLVA of 150 clinical isolates identified 13 MLVA types, including 3 predominant types. Our results show that isolates circulating in China differ from those in Western countries.

Staphylococcus aureus Internalized by Skin Keratinocytes Evade Antibiotic Killing

Staphylococcus aureus causes the majority of skin and soft tissue infections. Half of patients treated for primary skin infections suffer recurrences within 6 months despite appropriate antibiotic sensitivities and infection control measures. We investigated whether S. aureus internalized by human skin keratinocytes are effectively eradicated by standard anti-staphylococcal antibiotics. S. aureus, but not S. epidermidis, were internalized and survive within keratinocytes without inducing cytotoxicity or releasing the IL-33 danger signal. Except for rifampicin, anti-staphylococcal antibiotics in regular clinical use, including flucloxacillin, teicoplanin, clindamycin, and linezolid, did not kill internalized S. aureus, even at 20-fold their standard minimal inhibitory concentration. We conclude that internalization of S. aureus by human skin keratinocytes allows the bacteria to evade killing by most anti-staphylococcal antibiotics. Antimicrobial strategies, including antibiotic combinations better able to penetrate into mammalian cells are required if intracellular S. aureus are to be effectively eradicated and recurrent infections prevented.