Serotype distribution and antimicrobial susceptibility profile of invasive group B streptococcal disease-in South Indian population.

PURPOSE: Invasive group B Streptococcal disease (iGBS) is an important cause of morbidity and mortality in neonates for which the development of an efficacious vaccine remains a global health imperative. The knowledge about the serotype distribution of iGBS is important component for formulation of Capsular polysaccharide (CPS)-based vaccine. However, there were absolute lack of information on serotype distribution in invasive GBS isolates from Indian subcontinent. Methods This study has assessed the serotype distribution and antimicrobial susceptibility profile of invasive group B streptococcal isolates for a period of 13 years from 2009 to 2022 from a tertiary care Center in South India. A total of 155 iGBS isolates were subjected to serotyping by conventional multiplex PCR for identification of all ten GBS serotype. Antimicrobial susceptibility profile and demographic details were extracted from microbiological records. Results Overall, the most common serotype causing invasive GBS were Ia (29%), V (26%), III (15%), II (12%), VI (6%), VII (5%) and Ib (5%). Serotypes IV, VIII and XI were not detected. Among the early-onset iGBS, the common serotype were Ia (36%), V (27%), and III (8%). In late onset iGBS, Serotype III (44%) was predominant. The common serotype in adults were Serotype V (31%) and III (20%). All the invasive GBS isolates were susceptible for penicillin (100%), but the susceptibility for clindamycin and erythromycin were 72% and 80% respectively. Conclusion The serotype distribution of invasive Group B streptococcal isolates from India suggest that hexavalent group B CPS vaccine will cover only 90% of GBS isolates causing invasive disease among the infants in India. Continued surveillance monitoring for serotype distribution and antimicrobial resistance patterns for iGBS are warranted to make public health interventions.

In Vitro Activity of Two Cefepime-Based Novel Combinations, Cefepime/Taniborbactam and Cefepime/Zidebactam, against Carbapenemase-Expressing Enterobacterales Collected in India.

In recent times, discovery efforts for novel antibiotics have mostly targeted carbapenemase-producing Gram-negative organisms. Two different combination approaches are pertinent: ß-lactam-ß-lactamase inhibitor (BL/BLI) or ß-lactam-ß-lactam enhancer (BL/BLE). Cefepime combined with a BLI, taniborbactam, or with a BLE, zidebactam, has been shown to be promising. In this study, we determined the in vitro activity of both these agents along with comparators against multicentric carbapenemase-producing Enterobacterales (CPE). Nonduplicate CPE isolates of Escherichia coli (n = 270) and Klebsiella pneumoniae (n = 300), collected from nine different tertiary-care hospitals across India during 2019 to 2021, were included in the study. Carbapenemases in these isolates were detected by PCR. E. coli isolates were also screened for the presence of the 4-amino-acid insert in penicillin binding protein 3 (PBP3). MICs were determined by reference broth microdilution. Higher MICs of cefepime/taniborbactam (>8 mg/L) were linked to NDM, both in K. pneumoniae and in E. coli. In particular, such higher MICs were observed in 88 to 90% of E. coli isolates producing NDM and OXA-48-like or NDM alone. On the other hand, OXA-48-like-producing E. coli or K. pneumoniae isolates were nearly 100% susceptible to cefepime/taniborbactam. Regardless of the carbapenemase types and the pathogens, cefepime/zidebactam showed potent activity (>99% inhibited at ≤8 mg/L). It seems that the 4-amino-acid insert in PBP3 (present universally in the study E. coli isolates) along with NDM adversely impact the activity of cefepime/taniborbactam. Thus, the limitations of the BL/BLI approach in tackling the complex interplay of enzymatic and nonenzymatic resistance mechanisms were better revealed in whole-cell studies where the activity observed was a net effect of ß-lactamase inhibition, cellular uptake, and target affinity of the combination. IMPORTANCE The study revealed the differential ability of cefepime/taniborbactam and cefepime/zidebactam in tackling carbapenemase-producing Indian clinical isolates that also harbored additional mechanisms of resistance. NDM-expressing E. coli with 4-amino-acid insert in PBP3 are predominately resistant to cefepime/taniborbactam, while the ß-lactam enhancer mechanism-based cefepime/zidebactam showed consistent activity against single- or dual-carbapenemase-producing isolates including E. coli with PBP3 inserts.

Impact of COVID-19 Vaccination on Seroprevalence of SARS-CoV-2 among the Health Care Workers in a Tertiary Care Centre, South India.

Global vaccine development efforts have been accelerated in response to the devastating COVID-19 pandemic. The study aims to determine the seroprevalence of SARS-CoV-2 IgG antibodies among vaccine-naïve healthcare workers and to describe the impact of vaccination roll-out on COVID-19 antibody prevalence among the health care centers in tertiary care centers in South India. Serum samples collected from vaccinated and unvaccinated health care workers between January 2021 and April 2021were subjected to COVID-19 IgG ELISA, and adverse effects after the first and second dose of receiving the Covishield vaccine were recorded. The vaccinated group was followed for a COVID-19 breakthrough infection for a period of 6 months. Among the recruited HCW, 156 and 157 participants were from the vaccinated and unvaccinated group, respectively. The seroprevalence (COVID-19 IgG ELISA) among the vaccinated and unvaccinated Health Care Workers (HCW) was 91.7% and 38.2%, respectively, which is statistically significant. Systemic and local side-effects after Covishield vaccination occur at lower frequencies than reported in phase 3 trials. Since the COVID-19 vaccine rollout has commenced in our tertiary care hospital, seropositivity for COVID-19 IgG has risen dramatically and clearly shows trends in vaccine-induced antibodies among the health care workers.

Purpura Fulminans and Spotted Fever: A Case Series from South India.

Purpura fulminans (PF) is associated with acute infections such as meningococcal, staphylococcal, streptococcal, and rickettsial infections. However, there are only a few reports of association of PF with rickettsial fever from India. In this case series of seven adults with PF, four were definitive cases of spotted fever as the ompA real-time polymerase chain reaction was positive. The other three adults were probable cases of spotted fever, as they were positive by immunoglobulin M enzyme-linked immunosorbent assay, and their fever subsided within 72 h of rickettsia-specific therapy. Three of the seven patients had peripheral gangrene. These patients, despite presenting with severe spotted fever, had a favorable outcome. This is attributed to the high index of suspicion and early treatment supported by diagnostic assays.

Clinical characteristics of and antibody response to spotted fever group rickettsial infections in South India: Case series and serological cohort study.

OBJECTIVE: The clinical and serological characteristics of spotted fever group rickettsial (SFGR) infections in South Asia are poorly understood. We studied the clinical presentation and the IgM/IgG response in cases enrolled at two health care centres in South India. METHOD: We enrolled 77 patients. Fifty-seven of these patients were recruited at a tertiary care centre, the remaining 20 at a community hospital (secondary care level). Diagnostic tests included IgM and IgG enzyme-linked immunosorbent assay and polymerase chain reaction. Over a period of 1 year, 41 cases were followed up for repeated sero-analysis. RESULTS: Median age was 9 years (range 1-79). A rash was present in 74% of cases (57/77). In cases aged <15 years, rash was present in 94% (44/47) vs. 43% (13/30) in cases aged ≥15 years. An eschar was found in two cases (3%). Severe infection or complications occurred in 10 cases (13%). These included central nervous system infection (6/77, 8%), kidney injury (3/77, 4%), shock (3/77, 4%), lung involvement (2/77, 3%) and peripheral gangrene (2/77, 3%). IgM antibody levels increased faster after fever onset than IgG antibodies, peaking at 50 and 60 days, respectively. After the peak, IgM and IgG levels showed a slow decline over one year with less than 50% of cases showing persistent IgG antibody levels. CONCLUSION: Spotted fever group rickettsial infections in South India may be under-diagnosed, as many cases may not develop a rash. The proportion of cases developing severe infection seems lower than for scrub typhus in this region. IgG seroprevalence may substantially underestimate the proportion in a population with past SFGR infection.

Pneumococcal serotypes causing non-invasive pneumonia in adults from a South Indian tertiary care hospital and the impact of the newer conjugate vaccines.

BACKGROUND: Streptococcus pneumoniae is the leading cause of community-acquired pneumonia (CAP) in adults. Ageing, chronic conditions and comorbidities are important risk factors for pneumococcal pneumonia. PURPOSE: There is lack of data on the pneumococcal serotypes causing non-invasive pneumonia in India. This study aims to determine the prevalent pneumococcal serotypes causing non-invasive pneumonia, the associated comorbidities, and the coverage of both the available pneumococcal vaccines in India and conjugate vaccines that are currently undergoing clinical trials. METHODS: A total of 280 subjects (aged >16 years) who had clinical symptoms correlating with radiological findings for non-invasive bacteremic pneumonia and microbiological evidence of S. pneumoniae between 2018 and 2020 were included. The clinical, demographic, radiological and microbiological findings were retrieved from the Hospital Information System (HIS). RESULT: The common serotypes in order of prevalence were 19F, 9V, 23F, 6B, 11A, 13, 34, 10A, 19A and 6A. The predominant non-vaccine serotypes were 13, 34, 35B, 31 and 16F. The associated radiological findings were pneumonic consolidation and multi-lobar involvement. Other coinfected bacterial pathogens included H. influenzae, S. aureus, K. pneumoniae and P. aeruginosa. CONCLUSION: The pneumococcal vaccines: PCV10/GSK, PCV10/SII, PCV13, PCV15, PCV20 and PPSV23 provide an overall serotype coverage of 36, 41, 47, 48, 61 and 69 %, respectively of S. pneumoniae causing non-invasive pneumonia in South India. Increasing catch-up vaccination using PCV10(SII) in pre-school children could have a more significant impact on reducing pneumococcal pneumonia in adults (>50 years) in terms of increased herd immunity at an affordable cost.

Expected plazomicin susceptibility in India based on the prevailing aminoglycoside resistance mechanisms in Gram-negative organisms derived from whole-genome sequencing.

Background: Aminoglycoside resistance is a growing challenge, and it is commonly mediated by the aminoglycoside-modifying enzymes (AMEs), followed by 16S rRNA methyl transferase. Plazomicin, a novel aminoglycoside agent approved by the Food and Drug Administration for complicated urinary tract infections is proven to overcome resistance mediated by AMEs but not due to 16S rRNA methyl transferase (16SRMTases). We undertook this study to predict the efficacy of plazomicin in India based on the antimicrobial resistance profile derived from whole-genome sequencing (WGS). Methodology: A total of 386 clinical isolates of Escherichia coli, Klebsiella pneumoniae and Acinetobacter baumannii subjected to WGS were screened for aminoglycoside-resistance mechanisms such as AMEs and 16SRMTases and its association with carbapenemases. Results: AMEs was present in all E. coli, A. baumannii and in 90% of K. pneumoniae. In addition, up to 47% of E. coli and 38% of K. pneumoniae co-carried 16SRMTases with AMEs genes. However, A. baumannii showed 87% of isolates co-harbouring 16SRMTase. bla NDM, bla Oxa-48-like and bla Oxa-23-like were the most predominant carbapenemases in E. coli, K. pneumoniae and A. baumannii, respectively. Notably, 48% of NDM-producing E. coli and 35% of Oxa-48-like producing K. pneumoniae were identified to co-harbour AMEs + RMTAses, where plazomicin may not be useful. Conclusion: Overall, 53%, 62% and 14% of carbapenemase-producing E. coli, K. pneumoniae and A. baumannii harbours only AMEs, indicating the role of plazomicin use. Plazomicin can be used both for ESBLs as "carbapenem-sparing agent" and carbapenemase producers as "colistin-sparing agent." For optimal use, it is essential to know the molecular epidemiology of resistance in a given geographical region where plazomicin empirical therapy is considered.

Current strategy for local- to global-level molecular epidemiological characterisation of global antimicrobial resistance surveillance system pathogens.

The prime goal of molecular epidemiology is to identify the origin and evolution of pathogens, which can potentially influence the public health worldwide. Traditional methods provide limited information which is not sufficient for outbreak investigation and studying transmission dynamics. The recent advancement of next-generation sequencing had a major impact on molecular epidemiological studies. Currently, whole-genome sequencing (WGS) has become the gold standard typing method, especially for clinically significant pathogens. Here, we aimed to describe the application of appropriate molecular typing methods for global antimicrobial resistance surveillance system pathogens based on the level of discrimination and epidemiological settings. This shows that sequence-based methods such as multi-locus sequence typing (MLST) are widely used due to cost-effectiveness and database accessibility. However, WGS is the only method of choice for studying Escherichia coli and Shigella spp. WGS is shown to have higher discrimination than other methods in typing Klebsiella pneumoniae, Acinetobacter baumannii and Salmonella spp. due to its changing accessory genome content. For Gram positives such as Streptococcus pneumoniae, WGS would be preferable to understand the evolution of the strains. Similarly, for Staphylococcus aureus, combination of MLST, staphylococcal protein A or SCCmec typing along with WGS could be the choice for epidemiological typing of hospital- and community-acquired strains. This review highlights that combinations of different typing methods should be used to get complete information since no one standalone method is sufficient to study the varying genome diversity.

An emerging threat of ceftriaxone-resistant non-typhoidal salmonella in South India: Incidence and molecular profile.

Background: Non-typhoidal Salmonella (NTS) infection is a serious public health problem globally. Although NTS infections are self-limited, antimicrobial therapy is recommended for severe infections and immunocompromised patients. Antimicrobial resistance (AMR) in these pathogens further limits its therapeutic options. Here, we report an incidence of ceftriaxone resistance in NTS over the past 9 years in a southern Indian region. Materials and Methods: Molecular mechanisms of resistance in ceftriaxone-resistant NTS have been tested by both phenotypic and molecular methods. Minimum inhibitory concentration was determined by the E-test and broth microdilution method. AMR gene markers of ß-lactamases such as AmpCs (blaMOX, blaCMY, blaDHA, blaFOX, blaACC and blaACT) and extended-spectrum ß-lactamases (ESBLs) (blaSHV, blaTEM, blaVEB, blaPER, blaCTXM-1like,blaCTXM-2like, blaCTXM-8like, blaCTXM-9like and blaCTXM-25like) were screened. The presence of IncH12 and IncI1 plasmid was also analysed. Results: The study reports a 5% prevalence of ceftriaxone resistance in NTS. The most common serogroup was Salmonella Group B followed by Salmonella Group E and Salmonella group C1/C2. The occurrence of blaCTX-M-1, blaTEM, blaCMY and blaSHV genes was observed in 54%, 54%, 48% and 3% of the isolates, respectively. Interestingly, few isolates carried dual resistance genes (ESBLs and AmpCs). IncH12 and IncI1 plasmid was identified in isolates carrying ESBL and AmpC genes, respectively. Conclusion: This study shows that ceftriaxone resistance is mainly mediated by ß-lactamases such as ESBL and AmpC. As the incidence of ceftriaxone resistance is rising gradually over the years, it is imperative to monitor the AMR in this species.

Early outcome of culture-negative infection in open fractures of the lower limb: A prospective study.

Background: Culture-negative infections in open long bone fractures are frequently encountered in clinical practice. We aimed to identify the rate and outcome of culture-negative infections in open long bone fractures of lower limb. Methodology: A prospective cohort study was conducted from November 2015 to May 2017 on Gustilo and Anderson Grade III open long bone fractures of the lower limb. Demographic data, injury details, time from injury to receiving antibiotics and index surgical procedure were noted. Length of hospital stay, number of additional surgeries and occurrence of complications were also noted. Patients with infected open fractures were grouped as culture positive or culture negative depending on the isolation of infecting microorganisms in deep intraoperative specimen. The clinical outcome of these two groups was statistically analysed. Results: A total of 231 patients with 275 open fractures involving the femur, tibia or fibula were studied. There was clinical signs of infection in 84 patients (36.4%) with 99 fractures (36%). Forty-three patients (51.2%) had positive cultures and remaining 41 patients had negative cultures (48.8%). The rate of culture-negative infection in open type III long bone fractures in our study was 17.7%. There was no statistical difference in the clinical outcome between culture-negative and culture-positive infections. Conclusion: Failure to identify an infective microorganism in the presence of clinical signs of infection is routinely seen in open fractures and needs to be treated aggressively.

Microbiological profile of infections of the hip joint: An Indian perspective.

Background: Knowledge of the local microbiological epidemiology helps in formulating protocols for appropriate treatment of hip infections. The aim of this study was to profile the organisms cultured from infected hips. Methods: The microbiological profile and sensitivity pattern of organisms in eighty infected hips were reviewed. Results: Infection was secondary to arthroplasty in 35, fracture surgery in 34 and primary septic arthritis in 11. Twenty percent of the infections were polymicrobial, whereas the rest were monomicrobial. Fifty-five percent were Gram-positive, of which 45% were Staphylococcus species (36% methicillin-sensitive Staphylococcus aureus, 20% methicillin-resistant S. aureus, and 44% coagulase sensitive Staphylococcal species). All Staphylococcus species were sensitive to vancomycin, but 20% of Enterococcus species were resistant to vancomycin. One-third of the Enterococcus species and 2% of Staphylococcus species were resistant to teicoplanin. Escherichia coli (n = 10) and Pseudomonas sp. (n = 13) were the most common Gram-negative organism. Although 18% of the Gram-negative organisms were carbapenem resistant, all were sensitive to colistin. Conclusion: Staphylococcus sp. was the most common pathogen found in hip infections. However, the high incidence of Gram-negative infection requires that prophylactic antibiotics cover these organisms as well. The high resistance to first-line antibiotics should be taken into consideration while making protocols. The knowledge of the microbial profile is especially important when considering arthroplasty for arthritis secondary to hip infections.

Is it safe to do a single-stage implant exit and primary hip replacement? clinical and microbiological profiling.

Background: A single-stage implant revision for failed fixation of proximal femoral fractures is performed only when there is no evidence of infection. Else, a two-staged revision is preferred - where the definitive revision surgery is done a few months after the implant exit. This study aims to audit the safety and incidence of culture positivity in single-stage revisions. Materials and Methods: Forty one of 284 patients that presented over the last 12 years for implant exchange of the hip, had a single stage revision surgery for failed fixation of a fracture of the hip, as there was no obvious evidence of infection at the time of implant exit. Results: Micro-organisms were grown in 51% of the 41 hips. 76% were gram positive, of which 63% were Coagulase negative staphylococci (CoNS). 50% of CoNS and 75% of S. aureus were resistant to oxacillin, but susceptible to Vancomycin. Of the gram negative organisms, 2 (Enterobacter sp) were resistant to carbapenam, while others were susceptible. Preoperative ESR and CRP, individually, had low specificity - 50% for ESR >30mm at 1 hour and 62% for CRP>10. The combined use of ESR > 30mm and CRP>10 increased the specificity to 90%. 12% of the patients had immediate postoperative complications that required a wash out in theatre. The long term clinical follow up of these patients is limited. Conclusion: This study suggests that implant exit and simultaneous arthroplasty for failed fracture fixation should be done with caution due to the high possibility of infection. It may be prudent to opt for a 2 stage revision.

Assessment of two immunoassays for detection of IgM antibodies to scrub typhus using a serum panel.

Laboratory tests are necessary for diagnosis of scrub typhus (ST) especially in the absence of the distinctive eschar. Performance of an ELISA and ICT (immunochromatography) to detect IgM antibodies to scrub typhus was assessed using a panel of 346 sera chosen from healthy individuals, those with scrub typhus and scrub-typhus like illness. A sensitivity of 98.7% for ST IgM ICT and 97.4% for ST IgM ELISA was observed while specificity was 96.3% for ICT and 95.9% for ELISA. As excellent concordance (98.8%) was noted between the two assays, IgM ICT can be used for rapid diagnosis of scrub typhus. Abbreviations: ST IgM ELISA: Scrub typhus IgM ELISA; ST IgM ICT: Scrub Typhus IgM Immunochromatography, Rapid diagnostic test: RDT.

Efficacy ratio: A tool to enhance optimal antimicrobial use for intra-abdominal infections.

BACKGROUND: Antimicrobial resistance and inappropriate antibiotic regimen hamper a favorable outcome in intra-abdominal infections. Clinicians rely on the minimum inhibitory concentration (MIC) value to choose from the susceptible antimicrobials. However, the MIC values cannot be directly compared between the different antibiotics because their breakpoints are different. For that reason, efficacy ratio (ER), a ratio of susceptible MIC breakpoint and MIC of isolate, can be used to choose the most appropriate antimicrobial. MATERIALS AND METHODS: A prospective, observational study conducted during 2015 and 2016 included 356 Escherichia coli and 158 Klebsiella spp. isolates obtained from the intra-abdominal specimens. MIC was determined by microbroth dilution method, and ER of each antibiotic was calculated for all the isolates. RESULTS: For both E. coli and Klebsiella spp., ertapenem, amikacin, and piperacillin/tazobactam had the best activities among their respective antibiotic classes. DISCUSSION: This is the first study calculating ER for deciding empiric treatment choices. ER also has a potential additional value in choosing the use of susceptible drugs as monotherapy or combination therapy. A shift in ERs over a period of time tracks rising MIC values and predicts antimicrobial resistance development. CONCLUSION: Estimation of ER could be a meaningful addition for the interpretation of an antimicrobial susceptibility report, thus helping the physician to choose the best among susceptible antimicrobials for patient management.