Polymicrobial infection presenting as non-clostridial gas gangrene in a non-diabetic trauma patient. A case report and review of literature

BACKGROUND

Clostridium species are known to be the primary causative organism of gas gangrene. Non-clostridial gas gangrene (NCGG) is another rare necrotizing entity often associated with an underlying disease, particularly diabetes mellitus, and has a high mortality rate.

CASE REPORT

A 16-year-old, immunocompetent male was referred to us after four days, following a roadside accident, with a degloving injury over the thigh and knee along with fractures around the knee. Although clinico-radiologically suspicious of gas gangrene, the initial smear report was negative for any Gram-positive bacilli. On the same day, he underwent aggressive debridement with an external fixator spanning the knee to salvage the limb. On post-operative day one, due to deteriorating general clinical condition and a strong clinical suspicion of gas gangrene, he underwent above-knee amputation (open stump) after discussion with microbiologists and physicians.

RESULTS

Polymicrobial non-clostridial infection was seen in culture reports taken serially at different stages of management. The latest follow-up showed a healed amputation stump following split skin grafting.

CONCLUSION

Although rare, polymicrobial infections can present as non-clostridial gas gangrene even in an immunocompetent patient. A high index of clinical suspicion with a multi-disciplinary approach helps in early decision-making to avoid a devastating outcome.

Comparative evaluation of phenotypic and genotypic methods for the rapid and cost-effective detection of carbapenemases in extensively drug resistant Klebsiella pneumoniae

PURPOSE

Carbapenemases are the enzymes that can hydrolyze carbapenems and other β-lactam antibiotics. These enzymes confer resistance to multiple antibiotics and act as a stumbling block in the treatment of infections caused by gram-negative bacteria. Therefore, rapid and specific detection of these enzymes is crucial for deciding the course of treatment and better clinical outcomes.

MATERIAL AND METHODS

This study was conducted to compare various phenotypic and PCR based methods for the detection of carbapenemases in carbapenem- and colistin-resistant Klebsiella pneumoniae. One hundred clinical isolates of extensively resistant Klebsiella pneumoniae were included in the study. Phenotypic detection for carbapenemases was performed by Rapidec® Carba NP (Biomerieux), modified carbapenem inactivation method (mCIM), imipenem-ethylenediaminetetraacetic acid disk synergy (EDS), double disk synergy test using mercaptopropionic acid (DDST-MPA), and combined disk method (CD) and for colistin by microbroth dilution method. Genotypic detection for carbapenemases and colistin resistance was performed by targeted PCR.

RESULTS

The sensitivity of Carba NP test and mCIM were positive in 95% and 96% respectively and specificity was 100% for both methods. The sensitivity of EDS, DDST-MPA, and CD were 55.6%, 88.9% and 54.5% respectively. Among the carbapenem resistance genes, blaOXA-48 (82%) genes were the most prevalent. Among metallo-beta lactamases, blaVIM (56%) was most common followed by blaNDM (54%) and blaIMP (20%). The mcr-1 gene for colistin resistance was not detected in any isolate.

CONCLUSION

Among the five phenotypic assays analyzed, the mCIM is the most simple, inexpensive, accurate and reproducible method for carbapenemase detection in Klebsiella pneumoniae. The DDST-MPA test provides the best sensitivity for the detection of carbapenemases, although specificity is low. These tests, when applied in a clinical laboratory and assessed by the microbiologist, can help in guiding the course of treatment.

P105 In vitro interaction of Malassezia and commensal Staphylococcus species

 

Poster session 1, September 21, 2022, 12:30 PM - 1:30 PM

Objective

Malassezia is the most abundant fungal skin commensal organism, representing 50%–80% of total fungi present on the skin. It has been associated with many skin disorders such as pityriasis versicolor (PV) and seborrheic dermatitis/dandruff (SD/D). The role of Malassezia in disease manifestation is not discerned. It is important to understand its interaction with bacterial flora such as Staphylococcus epidermidis and S. capitis in vitro. We have studied the interaction of Malassezia and Staphylococcus species isolated from skin flora.

Methods

Malassezia restricta, M. globosa (n = 5) isolated from patients with SD and M. furfur (n = 5) isolated from PV were sub-cultured on Modified Dixon's agar (MDA). Staphylococcus epidermidis and S. capitis were isolated from patients with SD and sub-cultured on brain heart infusion (BHI) agar. Malassezia species requires media supplemented with lipids (MDA) for its growth. Bacteria and Malassezia were quantified on MDA and BHI agar by Miles and Mishra method to perform interaction between them. For direct interaction, suspensions (100 μl) of M. restricta, M. globose, and M. furfur were prepared in normal saline and added to wells on the plates of lawn cultures containing S. epidermidis and S. capitis (107 CFU/ml). Plates were incubated for 12 h at 35°C and observed for zone of inhibition. To investigate the release of antibacterial compounds into the extracellular environment, M. furfur was inoculated in modified Dixon's broth (MDB) and incubated at 35°C for 5 days. Supernatant was collected at 12 h, 24 h, 48 h, 72 h, 96 h, and 120 h of incubation and evaluated for antibacterial activity by agar-well diffusion assay. Effect of cell-free supernatant of Malassezia on growth of bacteria was also monitored by growth kinetics of S. epidermidis for 24 h in the absence and presence of M. furfur supernatant using Epoch-2 microplate spectrophotometer.

Results

MDA supported the growth of bacteria at different cell densities (107-103 CFU/ml count) and incubation time of S. epidermidis and S. capitis was similar on MDA and BHI. Zone of inhibition (ZOI) was witnessed with M. restricta (20.6 ± 3 mm, 21 ± 3 mm), M. globosa (21 ±1 mm, 22.6 ±2 mm) and M. furfur isolates (16.5 ± 1 mm, 18 ± 2 mm) against S. capitis and S. epidermidis respectively by direct interaction. Inhibition of bacteria by M. furfur was noted from 48-120 h as ZOI (21.7 ±5.1 mm) was observed on bacterial lawn cultured plate. When growth kinetics of S. epidermidis was monitored in presence of M. furfur supernatant, maximum value reached upto 0.26 ± 0.019 only from 0.01 ± 0.001 at OD600 in 9 h including lag phase of 4 h (Fig. 1). However, OD600 value reached upto 0.97 ± 0.005 in 8 h including lag phase of 1.5 h in absence of supernatant. Doubling time calculated from logistic growth equation was 76.6 ± 4.4 and 65.2 ± 2.9 minutes in the presence and absence of supernatant respectively.

Conclusion

Inhibition of bacteria by Malassezia species noted in our study has not been reported earlier. The possible production of antibacterial compounds by Malassezia might be responsible for dysbiosis leading to disease.

Extensive Multifocal Emphysematous Osteomyelitis of Spine: A Rare Case and a Review of Literature

BACKGROUND

Emphysematous osteomyelitis (EO) is an extremely rare form of osteomyelitis which is complicated mainly by infection with gas-forming organisms. The common causative agents of this disease are mainly members of Enterobacteriaceae family, the most common are Escherichia coli and Klebsiella pneumoniae along with anaerobes. A total of 48 cases of EO have been reported in the literature till now globally and none have documented the isolation of Corynebacterium amycolatum.

CASE PRESENTATION

We report a rare case of emphysematous osteomyelitis of the spine and pelvis due to Escherichia coli along with the isolation of Corynebacterium amycolatum from the same pus samples on two consecutive occasions in a 50-year-old female with uncontrolled diabetes mellitus, who was successively treated with antibiotics and drainage of pus. We also did a brief review of the literature of all cases reported till now.

CONCLUSION

The role of Corynebacterium amycolatum in the etiology of emphysematous osteomyelitis needs to be evaluated further in future studies as we cannot completely ignore its isolation in two consecutive samples as a mere contaminant.

Cluster outbreak of Pseudomonas stutzeri acute endophthalmitis following phacoemulsification: A report of 14 cases from North India

Purpose:

To report clinical features, antibiotic susceptibility profile, management, and outcomes of a cluster outbreak of post-cataract surgery Pseudomonas stutzeri endophthalmitis.

Methods:

This was a hospital-based case series in which 14 patients with acute postoperative endophthalmitis who underwent cataract surgery on the same day were included. Based on severity of presentation, they either underwent pars plana vitrectomy (PPV) with intraocular antibiotics (IOAB) or vitreous tap with IOAB. Vitreous aspirates and environmental surveillance samples were inoculated on culture media and further processed by MALDI-TOF MS for identification and Vitek3 for susceptibility profile.

Results:

There were 8 females and 6 males with a mean age of 62.14 ± 8.08 years. Presenting signs included corneal folds (100%), hypopyon (57.1%) and fibrin (50%). Ten patients with mild presentation underwent vitreous tap with IOAB. Four patients with severe presentation underwent PPV with IOAB. Pseudomonas stutzeri was isolated from the vitreous samples and was pan-sensitive. Six eyes required multiple interventions. Favorable outcome was obtained in 12 eyes, one eye developed phthisis, and one patient was lost to follow-up.

Conclusion:

We report the first ever cluster outbreak of Pseudomonas stutzeri endophthalmitis following phacoemulsification with IOL implantation in a single surgeon setting. Majority of the patients had a mild presentation and responded well to targeted anti-microbial treatment.

Colonization of the central venous catheter by Stenotrophomonas maltophilia in an ICU setting: An impending outbreak managed in time

BACKGROUND

Stenotrophomonas maltophiliacauses opportunistic infections in immunocompromised and patients in intensive care units (ICUs). An outbreak of S. maltophilia in ICU is described which highlights the importance of the risk of infection from contaminated medical devices and suction fluids in ventilated patients.

METHODS

The investigation of the outbreak was carried out. Environmental sampling was done. This was followed by MALDI-TOF MS typing and recA gene-based-phylogeny.

RESULTS

In February, S. maltophilia was reported from the central line blood of six patients from ICU within a span of two weeks. The peripheral line blood cultures were sterile in all patients. Relevant environmental sampling of the high-touch surface and fluids revealed S. maltophilia strains in normal saline used for suction and in the inspiratory circuit of two patients. The isolated strains from patients and environment (inspiratory fluid) showed a minimum of 95.41% recA gene sequence identity between each other. Strict cleaning and disinfection procedures were followed. Continuous surveillance was done and no further case of S. maltophilia was detected. Timely diagnosis and removal of central line prevented development of central-line associated blood stream infection.

CONCLUSION

This outbreak report illustrates that environmental sources like suction fluid and normal saline could be the source of S. maltophilia in ICU patients.

Effect of Reuse of Insulin Needle on Glycaemic Control and Related Complications in Children with Type 1 Diabetes Mellitus: A Prospective Observational Study

BACKGROUND

Children with type 1 diabetes (T1D) take multiple subcutaneous injections of insulin daily to survive. It is controversial whether the insulin needles can be reused safely or not. This study assesses the effect of the reuse versus single-use of insulin needle on glycaemic control and injection-related complications.

METHODS

Nearly 121 children (<15 years) with T1D were prospectively observed for existing practice of needle reuse for first 3 months and then were asked to practice single-use for the next 3 months.

RESULTS

It was found that 78% participants were reusing needles more than three times. After 3 months of needle reuse, 91.3% patients had lipodystrophy. Frequency of reuse positively correlated with local redness, bleeding and leakage of insulin. The patients achieving HbA1c ≤7.5% was significantly low among those reusing needles more than four times. After 3 months of single-use, no significant difference was found in mean HbA1c. However, hyperglycaemic episodes, lipodystrophy and local complications reduced significantly. There was a significant reduction in mean HbA1c among those using needles more than six times earlier.

CONCLUSION

Reuse of insulin needles up to six times does not affect the glycaemic control significantly. To achieve target HbA1c (<7.5%) the needle reuse should be restricted to three times only, which can also reduce injection-related local complications.

Association of Intra-Operative Bile Culture with Post-Operative Complications after Pancreaticoduodenectomy

Background: Infectious complications after pancreaticoduodenectomy (PD) are a major cause of morbidity. The association of bactibilia with the occurrence of surgical site infection (SSI) is debatable. Patients and Methods: Consecutive patients who underwent PD between July 2019 and December 2020 were included. All patients underwent standard pre-operative preparation and imaging. Pre-operative biliary drainage (PBD) was done as clinically indicated. A bile sample was collected just before the transection of common bile duct (CBD). Post-operative outcomes including SSI were analyzed. Results: Fifty-four patients were assessed for enrollment; 50 were found to be resectable during surgery and were included. The incidence of bactibilia was 46%. Nineteen (38%) patients developed SSIs and the occurrence was higher in patients who had positive bile culture (14 [60.8%] vs. 5 [18.5%]; p = 0.002). A similar organism between bile culture and SSI was seen in nine (64.2%) of 14 patients. Patients who had positive bile culture had more frequent change of antibiotic (16 [69%] vs. 8 [29.6%]; p = 0.005) and required prolonged duration of postoperative antibiotic agents (12 days [IQR, 8-14] vs. 8 days [IQR, 6-10]; p = 0.003). There was no association between bile culture growth and development of post-operative pancreatic fistula, delayed gastric emptying, and post-operative pancreatic hemorrhage. Patients with bactibilia had prolonged post-operative stay (17 days [IQR, 11-20] vs. 11 days [IQR, 8-14]; p = 0.010) and severe post-operative complications (8 [34.7%] vs. 2 [7.4%]; p = 0.008). Conclusions: Bactibilia is associated with the development of SSI and may provide a guide in selection of antibiotics.

Globicatella sanguinis corneal abscess with endophthalmitis

Globicatella sanguinis is a rare microorganism known to affect the bloodstream, urinary tract, and central nervous system. We report a case of Globicatella sanguinis ocular infection in a 9-year-old boy, who presented with a corneal abscess with endophthalmitis, following trauma. Isolation of the infection using matrix-assisted laser desorption ionization time-of-flight mass spectrometry and determination of its antibiotic sensitivity via Vitek 2 highlight the important role of microbiology laboratories for the diagnosis and management of infections caused by atypical microorganisms.

Secondary anaerobic infection in a case of multidrug resistant tubercular paraspinal abscess: A rare presentation

Introduction

Paraspinal abscesses are most commonly caused by Staphylococcus aureus and some Gram-negative bacteria. In developing countries, Mycobacterium tuberculosis (MTB) contributes to almost 50 % of cases. Even in proven cases of tubercular paraspinal abscesses, secondary infection of aerobic or anaerobic bacteria is possible and should be carefully evaluated for proper management.

Case report

A type I diabetes mellitus patient presented with chronic backache and lower limb weakness and radiological investigations showed paraspinal collections suggestive of tuberculosis. The patient was then started on anti-tubercular drugs, she initially responded and then showed gradual deterioration in the form of increased pain, fever and pus discharge. Aerobic cultures of pus were sterile and anaerobic culture grew Peptoniphilus asaccharolyticus sensitive to metronidazole. Appropriate treatment had resulted in clinical improvement.

Conclusion

Suspicion about co-infection with aerobic or anaerobic bacteria should be high even in proven cases of tubercular paraspinal abscess not improving despite proper anti-tubercular therapy.

Changing spectrum of infective endocarditis in India: An 11-year experience from an academic hospital in North India

Objective

Several studies have demonstrated a shift in the spectrum of infective endocarditis (IE) in the developed world. We aimed to investigate whether demographic and microbiologic characteristics of IE have changed in India.

Design

A retrospective analysis of patients with in north India between 2010 and 2020.

Methods

The clinical and laboratory profiles of 199 IE admitted to an academic hospital patients who met the modified Duke criteria for definite IE were analysed.

Results

The mean age was 34 years, and 84% were males. The main predisposing conditions were injection drug use (IDU) (n = 71, 35.7%), congenital heart disease (n = 46, 21.6%), rheumatic heart disease (n = 25, 12.5%), and prosthetic device (n = 19, 9.5%). 17.1% of patients developed IE without identified predispositions. Among 64.3% culture-positive cases, the most prevalent causative pathogens were Staphylococcus aureus (46.1%), viridans streptococci (7.0%), enterococci (6.0%), coagulase-negative staphylococci (5.5%), gram negative bacilli (5.5%), polymicrobial (5.5%), and Candida (1.0%). The tricuspid (30.3%), mitral (25.6%), and aortic (21.6%) valves were the most common sites of infection, and 60.3% had large vegetations (>10 mm). Systemic embolization occurred in 55.3% of patients at presentation. Cardiac surgery was required for 13.1%. In-hospital mortality was 17.1% and was associated with prosthetic devices (p-value, 0.001), baseline leucocytosis (p-value, 0.036) or acute kidney injury (p-value, 0.001), and a microbial etiology of gram negative bacilli or enterococci (p-value, 0.005).

Conclusion

IDU is now the most important predisposition for IE in India, and S. aureus has become the leading cause of native valve endocarditis with or without IDU.

Clinical anaerobic infections in an Indian tertiary care hospital: A two-year retrospective study

OBJECTIVE

To study the spectrum of anaerobic infections and the frequency of clinically relevant anaerobes in various infections in a tertiary care hospital in North India.

METHOD

In this two-year (2018-2019) retrospective study, a total of 22,177 samples were processed both anaerobically and aerobically. The samples included blood, pus, body fluids, necrotic tissues, abscess, peritoneal fluids, and other specimens of conditions predisposing to anaerobic infections. The recovered bacterial isolates were identified by matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS).

RESULT

Of the 22,177 samples processed anaerobically, 1094 showed significant anaerobic growth yielding 1464 anaerobes. Bacteroides fragilis (12.7%) and Peptoniphilus harei (12.2%) were the most predominant anaerobes, whereas Escherichia coli (32.6%) and Staphylococcus aureus (13.2%) were the most frequently recovered facultative anaerobes in polymicrobial growth. Both aerobic and anaerobic data were available for 673/1094 samples, of which 68% represented a polymicrobial etiology and 32% as monomicrobial. Of the cases where complete clinical information was available (504/1094), the majority of the anaerobes were recovered from the skin and soft tissue infections (36.3%) and intra-abdominal infections (17.1%). The clinical specimen most frequently growing anaerobes was abscess (29.1%), followed by diabetic foot ulcers (14.1%).

CONCLUSION

The study documents the frequency of clinically significant anaerobic bacteria in various infections, and their associations with aerobes in polymicrobial growth. The present study may aid us in devising better therapeutic strategies against both aerobes and anaerobes in anaerobic infections, which is often empirical. Besides, the data can update clinicians with the changing patterns of anaerobic infections, which remains a neglected concern.

Factors affecting decontamination of N95 masks for reuse: Feasibility & practicality of various methods

The SARS-CoV-2 pandemic has led to an enormous increase in cases worldwide in a short time. The potential shortage might call for the reuse of personal protective equipment especially N95 masks. In this review, the methods available for decontamination of N95 masks have been compared to highlight the advantages and efficacies of different methods. Studies conducted to evaluate the biocidal efficacy, effect on filtration efficacy of the decontamination method, and maintenance of structural integrity of masks, were reviewed. Ultraviolet germicidal irradiation (UVGI) and hydrogen peroxide (H2O2) vapour were the most commonly evaluated interventions and showed good germicidal activity without significant deleterious effects on mask performance. Vapourous H2O2 was the best method as it maintained NIOSH (The National Institute for Occupational Safety and Health) recommendations of the mask on re-use and additionally, one mask could be decontaminated and reused 30 times. Ethylene oxide (EtO) preserved the maximum filtration efficacy and flow resistance. Chemical and heat-based methods had the advantages of being cost-effective and feasible but affected the structural integrity and fit of the masks. For the decontamination of N95 masks, among the heat-based methods steam was found to be the best for low middle-income countries setting. H2O2-based methods, UVGI, and EtO all exhibited both adequate biocidal efficacies and functionality (fit testing and structural integrity). Further studies on logistics, healthcare worker acceptability of reuse, and actual efficacy of protection against SARS-CoV-2 infection should be carried out to validate the use of decontamination in the real-life settings.

Bacterial coinfections and secondary infections in COVID-19 patients from a tertiary care hospital of northern India: Time to adhere to culture-based practices

OBJECTIVE

Bacterial co-pathogens are common in various viral respiratory tract infections, leading to increased disease severity and mortality. Still, they are understudied during large outbreaks and pandemics. This study was conducted to highlight the overall burden of these infections in COVID-19 patients admitted to our tertiary care hospital, along with their antibiotic susceptibility patterns.

MATERIAL AND METHODS

During the six-month study period, clinical samples (blood samples, respiratory samples, and sterile body fluids, including cerebrospinal fluid [CSF]) of COVID-19 patients with suspected bacterial coinfections (at presentation) or secondary infections (after 48 hours of hospitalization) were received and processed for the same.

RESULTS

Clinical samples of 814 COVID-19 patients were received for bacterial culture and susceptibility. Out of the total patient sample, 75% had already received empirical antibiotics before the samples were sent for analysis. Overall, 17.9% of cultures were positive for bacterial infections. Out of the total patients with bacterial infection, 74% (108/146) of patients had secondary bacterial infections (after 48 hours of hospitalization) and 26% (38/146) had bacterial coinfections (at the time of admission). Out of the 143 total isolates obtained, the majority (86%) were gram-negative organisms, of which Acinetobacter species was the commonest organism (35.6%), followed by Klebsiella pneumoniae (18.1%). The majority (50.7%) of the pathogenic organisms reported were multidrug resistant.

CONCLUSION

The overall rate of secondary bacterial infections (SBIs) in our study was lower (7.9%) than reported by other studies. A rational approach would be to adhere to the practice of initiating culture-based guidance for antibiotics and to restrict unnecessary empirical antimicrobial therapy.

Skull base osteomyelitis by Pandoraea apista: An unusual pathogen at unusual location - A case report

Background:

Pandoraea apista is predominantly recovered from the respiratory tract of patients with cystic fibrosis (CF). Authors report first case of central nervous system infection by P. apista in the form of skull base osteomyelitis.

Case Description:

A 67-year-old male presented with complaints of earache and hearing deficit for few months. The radiology was suggestive of skull base osteomyelitis and polypoidal soft tissue extending from the middle cranial fossa to the infratemporal fossa. The sample from the targeted area revealed P. apista on matrix-assisted laser desorption ionization-time-of-flight mass spectrometry. With adequate antibiotic therapy, there was clinicoradiologic improvement. P. apista is an infection exclusively seen in pulmonary infection in patients with CF. We identified its intracranial involvement in a patient for the 1^st time in the literature. The serendipitous diagnosis needs evaluation on specific PCR and matrix-assisted laser desorption spectrometry. The treatment with antibiotics provides a definite cure.

Conclusion:

We report a rare opportunistic infection with central nervous system involvement which can be cured by accurate diagnosis and appropriate antibiotic treatment.

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

Background and Objectives:

Anaerobic infections are usually caused by the host’s endogenous flora due to a breach in the anatomical barriers and Bacteroides spp. are the most notorious organisms associated with anaerobic infections. The identification of anaerobes has been a challenge since times. MALDI-TOF-MS is a boon for aiding the rapid detection of anaerobic organisms and has helped us to enlist the distribution of various anaerobic pathogens.

Materials and Methods:

This retrospective analysis (January 2018 to December 2019) was carried out in a tertiary care hospital in North India, in which the anaerobic microbiological profile of all patients admitted to surgical wards, ICU, and OPD of various departments (Orthopedics, Surgery, Gynecology, and Obstetrics) was reviewed. Samples received were immediately processed aerobically (5% sheep blood agar and Mac Conkeyagar) as well as anaerobically (RCM and freshly prepared sheep blood agar) as per the laboratory protocols.

Results:

Bacteroides fragilis (19.12%) was the most common anaerobe whereas among aerobes Escherichia coli (30.2%) followed by Klebsiella pneumoniae (10.34%) were most commonly isolated. The majority of patients were males (56%) and the most common presentation was with abscesses (21.4%). Polymicrobial infections (69.51%) outnumbered monomicrobial ones (30.48%).

Conclusion:

There is a paucity of literature on anaerobe isolation from surgical infections from our country which motivated us to study anaerobic infections and the high sample size in our institute enabled us to study surgical infections from an anaerobic perspective. This will add to the knowledge of microbiologists and clinicians. MALDI-TOF MS helped in rapid and accurate identification and hence we could report a wider spectrum of organisms in our study.

Comparative evaluation of agar dilution and broth microdilution by commercial and in-house plates for Bacteroides fragilis group: An economical and expeditious approach for resource-limited settings

OBJECTIVE

To compare the performance of agar dilution and broth microdilution by commercial and in-house prepared plates for the Bacteroides fragilis group. The cost analysis was performed to demonstrate that in-house prepared BMD plates were a suitable alternative to agar dilution given the high cost and low feasibility of incorporating commercial BMD plates in routine, particularly in the tertiary care institutes of many low- and middle-income countries.

METHODS

Thirty B. fragilis group isolates were tested against six antibiotics, frequently used as empirical therapy for anaerobic infections including metronidazole, clindamycin, imipenem, piperacillin-tazobactam, cefoxitin, and chloramphenicol. The running consumable expenditure for all methodologies was calculated.

RESULTS

The results demonstrated essential and categorical agreement of >90% for all antibiotics except cefoxitin, which showed <90% categorical agreement. No major or very major errors were observed. We observed a high agreement and strong concordance for MIC values between both methods and inter-rate reliability of >0.9 by Cohen's kappa analysis, indicating almost perfect agreement between both methods using either of the plates. In contrast to agar dilution, a 20.5 fold cost reduction was seen in BMD using in-house plates and a 5.8 fold reduction using commercial plates to test a single isolate. However, when testing 30 isolates concurrently the cost significantly increased for commercial BMD plates by 8.4 folds, and only 1.03 fold cost reduction was seen with in-house BMD plates.

CONCLUSION

BMD gives comparable results to agar dilution and can be considered a method of choice to test a small number of samples. The technique is an economical option when plates are standardized in-house and could be employed for susceptibility testing of the B. fragilis group.

Phenotypic and genotypic antimicrobial resistance in clinical anaerobic isolates from India

BACKGROUND

Antimicrobial resistance (AMR) in anaerobes remains a neglected field. The laborious procedures, non-compliance with the standard methodology and differences in interpretive breakpoints add variation in resistance data.

OBJECTIVES

To assess the phenotypic and genotypic resistance among clinically important anaerobes to six antibiotics frequently used as empirical therapy for anaerobic infections.

METHODS

A total of 150 anaerobic isolates were recovered from clinical specimens. The antimicrobial susceptibility was determined by the breakpoint agar dilution method as per CLSI guidelines. The presence of genes encoding resistance to metronidazole (nim gene), imipenem (cfiA gene) and mobilizable insertion sequence (IS) elements was detected to comprehend their association with phenotypic resistance.

RESULTS

This is a first study of its kind from the Indian subcontinent looking at the AMR and associated genes in anaerobes. Resistance to metronidazole, clindamycin, imipenem, piperacillin/tazobactam and cefoxitin was 32.6%, 42.6%, 0.6%, 38% and 35.3%, respectively. No resistance was observed to chloramphenicol. The nim gene was detected in 24.6% of isolates, of which 70.2% were resistant by phenotype. On sequencing, the PCR products of six random nim genes showed a close similarity to nimE of Bacteroides fragilis with 99% nucleotide and 100% amino acid sequence similarity. The cfiA gene, associated with imipenem resistance, was detected in 16% of isolates.

CONCLUSIONS

The possibility of isolates carrying AMR genes to become resistant to antibiotics by acquisition of IS elements mandates attention to periodically monitor the resistance patterns and geographic distribution of these genes and IS elements to understand the trends of AMR in anaerobes.

Detection of co-infection of Gardnerella vaginalis and Atopobium vaginae using qualitative PCR: A better predictor of bacterial vaginosis

The present study aimed to determine the utility of detection of co-infection of Gardnerella vaginalis and Atopobium vaginae using qualitative PCR for diagnosing bacterial vaginosis (BV). Vaginal samples (n = 385) categorized as positive (n = 108) or negative (n = 208) for bacterial vaginosis based on the Nugent scoring system, were analyzed for the presence of G. vaginalis and A. vaginae by conventional PCR. We compared the sensitivity, specificity, positive predictive value, negative predictive value and odds ratio for the detection of each bacterium alone with the combination of the two bacteria for diagnosing BV. The detection of co-infection of the two bacteria demonstrated a sensitivity of 96%, a specificity of 82.9%, a positive predictive value of 68.5%, a negative predictive value of 98.2% with an odds ratio of 116 (CI -32 - 409). In our study, we found a high sensitivity, specificity, negative predictive value and odds ratio for the detection of co-infection of A. vaginae and G. vaginalis for the diagnosis of BV.