Nonfermenting Gram-negative Bacilli Isolates Research Articles

Clinical and microbiological features of positive blood culture episodes caused by non-fermenting gram-negative bacilli other than Pseudomonas and Acinetobacter species (2020-2023).

Non-fermenting Gram-negative bacilli (NFGNB) other than Pseudomonas aeruginosa and Acinetobacter baumannii complex are pathogens of interest due to their ability to cause health-care associated infections and display complex drug resistance phenotypes. However, their clinical and microbiological landscape is still poorly characterized. Observational retrospective study including all hospitalized patients presenting with a positive positive blood culture (BC) episode caused by less common NFGNB over a four-year period (January 2020-December 2023). Clinical-microbiological features and factors associated with mortality were investigated. Sixty-six less common NFGNB isolates other than Pseudomonas and Acinetobacter species causing 63 positive BC episodes were recovered from 60 patients. Positive BC episodes were predominantly sustained by Stenotrophomonas maltophilia (49.2%) followed by Achromobacter species (15.9%) that exhibited the most complex resistance phenotype. Positive BC episodes had bloodstream infection criteria in 95.2% of cases (60 out 63), being intravascular device (30.2%) and respiratory tract (19.1%) the main sources of infection. Fourteen-day, 30-day, and in-hospital mortality rates were 6.4%, 9.5%, and 15.9%, respectively. The longer time from admission to the positive BC episode, older age, diabetes, admission due to sepsis, and higher Charlson Comorbidity Index were identified as the main predictors of in-hospital mortality. Positive BC episodes sustained by NFGNB other than Pseudomonas and Acinetobacter species were predominantly sustained by Stenotrophomonas maltophilia and Achromobacter species, having bloodstream infection criteria in the vast majority of cases. Factors that have emerged to be associated with mortality highlighted how these species may have more room in prolonged hospitalisation and at the end of life for patients with chronic organ diseases.

Trends in Antimicrobial Resistance in a Tertiary Care Hospital of Assam, India

Antimicrobial resistance (AMR) in bacterial pathogens has emerged as a challenge in health care settings resulting in high rates of morbidity and mortality. The aim of the present study was to describe the trends and burden of AMR in a tertiary care hospital. A retrospective observational study was undertaken from October 2018 to March 2021 in a clinical microbiology laboratory where local priority pathogens and their antimicrobial resistance patterns were analyzed. Organism identification and antimicrobial susceptibility testing were performed as per Clinical and Laboratory Standards Institute guidelines. Out of 9948 isolates, Enterobacteriaceae (58%) were mostly isolated followed by Staphylococci (18.6%), Non-fermenting gram negative bacilli (NFGNB) (13.7%), and Enterococci (8.4%) respectively. Highest isolation was from inpatient department (61.3%); 31.5% from outpatient, and 7.2 % from intensive care units. Klebsiella pneumoniae (26.9%) was most isolated organism, mostly from respiratory samples; Escherichia coli was isolated mostly from urine (40.7%). Almost half of the Enterobacteriaceae isolates were extended spectrum beta-lactamase producers while >50% of Enterobacteriaceae and NFGNB isolates were resistant to one or more Carbapenems. Frequency of Methicillin resistant Staphylococcus aureus was 44.7% , Vancomycin resistant Enterococci was 1.2%. A rising trend of resistance to cephalosporins and carbapenems along with fluoroquinolones was observed. Our study has witnessed a high prevalence of Gram negative pathogens with increasing resistance to commonly applied antimicrobials during the surveillance period which can act as a guiding tool in devising local antimicrobial priorities, antibiotic policy, and proper antimicrobial prescribing practices.

The Role of Automation for Early Diagnosis of Non-fermenter Superbugs in Critically Ill Septicemic Hospitalized Patients.

Introduction Non-fermenting Gram-negative bacilli (NFGNB) are emerging superbugs of bloodstream infections (BSI), causing increased mortality in hospitalized patients. NFGNB are challenging to identify using conventional identification techniques. Hence, automation is beneficial for accurate and fast diagnosis; it also facilitates rapid treatment and recovery of patients. This study aims to isolate/identify NFGNB from BSI and determine its antimicrobial susceptibility pattern. Material and methods This study was conducted in the Department of Microbiology, LLRMMC, Meerut, for a period of six months (June to November 2022). The samples were processed using automated blood culture (BD BACTEC) and an identification/sensitivity testing system (BD Phoenix). Results Out of 1340 blood cultures, 347 (25.7%) were flagged positive for microbial growth. A total of 103 (7.6%) NFGNB were isolated, showing their strong association with BSI. The NFGNB isolates were Pseudomonas species 23 (22.3%), Acinetobacter baumannii 19 (18.4%), Salmonella spp. 19 (18.4%), Sphingomonas paucimobilis 17 (16.5%), Aeromonas hydrophila 5 (4.8%), Rhizobium radiobacter sp. 4 (3.8%), Stenotrophomonas maltophila 3 (2.9%), Burkholderia cepacian 3 (2.9%), Proteus mirabilis 2 (1.9%), Achromobacter xylosoxidans 2 (1.9%), Elizabethkingia meningoseptica 2 (1.9%), Ochromobacter anthropic 2 (1.9%), Cuprivadus pauculus 1 (0.9%), and Ralstonia mannitolilytica 1 (0.9%). Conclusions Automation helps in the prompt reporting of NFGNB and their antibiogram pattern by microbiology laboratories, facilitating the early and accurate management of patients with BSI.

Antibiofilm and antimicrobial activity of curcumin-chitosan nanocomplexes and trimethoprim-sulfamethoxazole on Achromobacter, Burkholderia, and Stenotrophomonas isolates

ABSTRACT Background Non-fermenting Gram-negative Achromobacter xylosoxidans, Burkholderia cepacia complex, and Stenotrophomonas maltophilia species cause healthcare-associated infections, often showing resistance to first-line drugs such as trimethoprim-sulfamethoxazole (TMP-SXT). The aim of this study was to determine the effect of curcumin-chitosan nanocomplexes on biofilm-producing clinical isolates of non-fermenting Gram-negative bacilli. Methods A. xylosoxidans, B. cepacia complex, and S. maltophilia clinical isolates were identified by MALDI-TOF mass spectrometry. Antimicrobial susceptibility was determined by broth microdilution. Curcumin (Cur), chitosan (Chi), and sodium tripolyphosphate (TPP) were encapsulated by ionotropic gelation in magnetic nanoparticles (MNP) and were assessed by scanning electron microscopy (SEM) and Fourier-transform infrared (FTIR). Biofilm inhibition and eradication by Cur-Chi-TPP-MNP with TMP-SXT was assessed. Results Cur-Chi-TPP-MNP in combination with TMP-SXT showed biofilm inhibition activity in A. xylosoxidans (37.5 µg/mL), B. cepacia (18.75 µg/mL), and S. maltophilia (4.69–18.75 µg/mL) and low biofilm eradication activity in all three strains (150 − 300 µg/mL). Conclusions Cur-Chi-TPP-MNP in combination with TMP-SXT was able to inhibit biofilm and in lower effect to eradicate established biofilms of clinical isolates of A. xylosoxidans, B. cepacia complex, and S. maltophilia species. Our results highlight the need to assess these potential treatment options to be used clinically in biofilm-associated infections.

The Modified Carbapenem Inactivation Method (mCIM): Highly sensitive and specific low-cost tool to assess carbapenemase-producing and non-producing in Gram-negative bacilli

Introduction: Carbapenemase-producing Gram-negative bacilli is a worldwide problem, which represent a health concern, because most of its resistance mechanisms are encoded by plasmids, therefore easily transmissible in hospital settings. Many methods have been proposed to detect such resistance, but screening is still challenging, recently the modified carbapenem inactivation method has shown promising results, however more studies need to be performed. Hence, this study aimed to evaluate the performance of the mCIM in carbapenem-resistant Enterobacteriaceae and nonfermenting Gram-negative bacilli isolates.
 Materials and methods: From a microbial collection with molecular characterization of carbapenemase genes previously conducted, 100 Gram-negative bacilli isolates were selected, fifty-two non-carbapenemase producing and 48 carbapenemase-producing isolates. The mCIM was performed according to the CLSI guidelines, and to assess the validity of the method sensitivity and specificity were calculated.
 Results: The sensitivity of the mCIM observed in this study was 96% (46/48) and the specificity was 96,2% (50/52). Most of the Gram-negative bacilli carrying a carbapenemase gene were mCIM-positive, moreover, in carbapenem-resistant isolates that do not produce a carbapenemase (Enterobacteriaceae and non-fermenters) the results of the mCIM were negatives.
 Conclusion: Overall the mCIM provides a low-cost alternative for the screening of carbapenemase-producing Gram-negative bacilli. Our findings highlight that mCIM is a sensitive and specific method to assess carbapenemase-producing in Gram negative bacilli non-fermenters and Enterobacteriaceae as Enterobacter cloacae.

Non-fermenting gram negative bacilli isolated from blood and their in vitro sensitivity pattern in a tertiary care hospital

Background: Bacteremia caused by non-fermenting gram negative bacilli (NFGNB) is a serious infection which is associated with high morbidity and mortality. Identification of NFGNB and monitoring their susceptibility pattern are important for proper management of these infections. Aim: Scope of the present study is to characterize the NFGNB along with their antimicrobial sensitivity pattern among the patients coming to our hospital, a tertiary care center. Materials & Methods: A retrospective study was conducted to determine the NFGNB isolated from blood during the one-year study period. A total of 8223 Blood cultures were received in the laboratory which was processed by semi-automated technique in Bac-T Alert. Antibiotic susceptibility was performed by VITEK and Kirby Bauer methods and interpreted by CLSI guidelines. 102 isolates of NFGNB were obtained from the Blood culture. Results: Most commonly isolated organism is Acinetobacter species (47%) followed by Pseudomonas spp (27%) and Burkholderia spp(15.6%). Maximum isolates of Acinetobacter spp were sensitive to colistin (91.9%), cefoperazone-sulbactum (88.4%), Tigecycline (62.5%). Pseudomonas spp was sensitive to colistin (100%), ciprofloxacin (59%). Conclusion: Identification of NFGNB and monitoring their susceptibility patterns will help in proper management of infections caused by them.

A Study of Isolation, Identification & Antibiotic Susceptibility Pattern of Non-Fermenting Gram Negative Bacilli Isolated From Various Clinical Samples at Tertiary Care Hospital Rajkot, Gujarat, Western India

Introduction: Nonfermenting gram-negative bacilli (NFGNB) are a taxonomically diverse group of aerobic, nonsporing, bacilli that either do not utilize glucose as a source of energy or utilize it oxidatively. They occur as saprophytes in the environment and some are also found as commensals in the human gut. In recent year NFGNB have emerged as important health care associated pathogens. They have been incriminated in infections such as bacteremia, meningitis, pneumonia, urinary tract infections, surgical site infections, wound infections, osteomyelitis etc. Materials and method: During Nine Month study period, various samples were collected aseptically and transported immediately to the bacteriology laboratory. The pathogens were identified by standard laboratory procedures including Gram’s staining, motility, culture, colony characters and biochemical reactions. Antimicrobial susceptibility testing was performed by modified Kirby Bauer method as per the CLSI guidelines using Muller-Hinton agar and available antibiotic disks. Result: A total number of 312 NFGNB were isolated from 4112 clinical samples. Most frequently isolates NFGNB were Pseudomonas aeruginosa (42.62%) and Acinetobacter spp. (25.32%). NFGNB isolates were more common in males (58.33%) as compared to females (41.67%). Maximum sensitivity was seen to Polymyxin B (100%), Meropenem (83.45) in Pseudomonas aeruginosa and Meropenem (78.48%), Pipracillin-tazobactum (62.02%) in Acinetobacter spp. Conclusion: NFGNB are emerging as important pathogens and shows resistance to commonly used antibiotics. Minimized use of available antimicrobial, regular use antimicrobial susceptibility surveillance and strict infection control measures are required to control this emerging antimicrobial resistance among NFGNB.

Assessment of Prevalence and Antibiogram of NFGNB isolates in a Tertiary care Hospital, Dehradun

Non-fermenting Gram Negative Bacilli (NFGNB) is emerging as a major cause of nosocomial infections as they exhibit great multidrug resistance thereby posing difficulty in combating the infections. Studies on assessing the prevalence rate and antibiogram of NFGNB is necessary for proper management of infections caused by them as there are high chances of regional variation in predominance and antimicrobial susceptibility pattern of NFGNB. Aim of the present study was to assess the prevalence rate of NFGNB along with antimicrobial sensitivity pattern revealing their drug sensitivity and resistance among the patients attending tertiary care hospital of varied age groups. A total of 1000 various clinical specimens were received in laboratory during the period of 4 months (August 2020-Novemebr 2020) and were subjected to processing using Vitek-2 compact system. Among 1000 clinical samples 328 yielded NFGNB i.e., Pseudomonas aeruginosa, Acinetobacter baumannii, Achromobacter Xylosoxidans, Stenotrophomonas maltophilia and Burkholderia cepcia. Pseudomonas aeruginosa (51.82%) and Acinetobacter baumannii (39.63%) were most prominent NFGNB isolates. Results showed that although NFGNB were found to be resistant against most of the subjected antibiotics but considerable intensity of effectiveness was also recorded against Colistin. Accurate, rapid identification and antimicrobial susceptibility testing of NFGNB by Vitek 2, is required in early diagnosis, treatment and proper management of patients will reduce emergence of MDR strains of NFGNB.

Lipid kinetics in patients with non-fermenting Gram-negative bacterial ventilator-associated pneumonia.

In non-fermenting Gram-negative bacilli (NFGNB) infections, the interaction between the immune system of the host and the bacteria plays a more important role in determining the pathogenesis than the virulence factors of bacteria per se. We aimed to evaluate the sequential changes in the inflammatory response, including the lipid profile, antimicrobial susceptibility, and outcomes in NFGNB ventilator-associated pneumonia (VAP). A total of 81 patients who developed NFGNB VAP were divided into two groups, namely multi-drug resistant (MDR) (n=51) and non-MDR (n=30) groups. When compared with the control group, the cholesterol levels of VAP patients decreased, while the levels of C-reactive protein and procalcitonin (PCT) levels significantly increased (p<0.05). The best sensitivity (93 %) corresponds to PCT levels on day 4, and the best specificity (89 %) corresponds to the levels of high-density lipoprotein (HDL) on day 4, which makes the latter parameters suitable candidates for predicting the 30-day mortality. The impact of resistant NFGNB isolates on early and late mortality rates was similar. In NFGNB VAP patients, the change relative to antimicrobial resistance was not appreciated in either the systemic inflammatory response or disease severity. MDR NFGNB isolates were not associated with greater mortality in VAP patients. The decrease in serum HDL and increase in PCT on day 4 indicated a poor prognosis (Tab. 5, Fig. 2, Ref. 30).

Antibiotic resistance of bacteria responsible for lower respiratory tract infections seen in the University Hospital of Befelatanana Antananarivo Madagascar

The majority of bacteria responsible for Lower Respiratory Tract Infections (LRTIs) are multiresistant to antibiotics. The objectives of this study are to describe the antibiotic resistance of these bacteria in LRTIs and to describe the factors associated with these infections. It is a prospective study of 54 respiratory samples of patients with LRTIs for a period of six months from July 2019 to December 2019 in the laboratory of the University Hospital of Befelatanana Antananarivo. The microbiological results showed 12 (22%) isolates of nonfermenting gram-negative bacilli, 10 (19%) isolates of streptococci and 6 (11%) isolates of enterobacteria. Regarding the isolates of nonfermenting gram-negative bacilli, the antibiotic resistance, varies from 42% (amikacin) to 100% (cotrimoxazole). Concerning the isolates of streptococci, it varies from 0% (vancomycin) to 80% (penicillin G). And the antibiotic resistance of the isolates of enterobacteria varies from 0% (imipenem and amikacin) to 100% (amoxicillin). Concerning the associated factors, subjects aged 40 and over (58.6%) (p = 0.84; NS), men (71.4%) (p = 0.01) and subjects hospitalized in intensive care units (70.3%) (p = 0.004) are the most affected by LRTIs. In brief, the knowledge of antibiotic resistance of bacteria responsible for LRTIs allows better patient management.

Comparison of the Xpert Carba-R and NG-Test CARBA5 for the detection of carbapenemases in an IMP-type carbapenemase endemic region in Japan

IntroductionThe real-time PCR assay Xpert Carba-R and the lateral flow immunoassay NG-Test CARBA5 were developed to detect 5 types of carbapenemase genes (blaIMP, blaKPC, blaVIM, blaOXA-48, and blaNDM). MethodsWe compared the diagnostic performance, turn-around time, and cost of these assays. Carbapenemase genes were defined using the Carba NP test, modified Carbapenem Inactivation Methods (mCIM), multiplex PCR, and whole-genome sequencing. We included clinical Enterobacterales isolates (n = 36) and nonfermenting gram-negative bacilli isolates (n = 17) collected from 16 acute-care hospitals in the Kinki region of Japan. ResultsTwenty-six of these 53 isolates were positive according to both of the Carba NP test and mCIM and, contained the following carbapenemase genes: blaIMP-1 (n = 3), blaIMP-6 (n = 1), blaIMP-19 (n = 12), blaIMP-26 (n = 1), blaIMP-41 (n = 2), blaIMP-66 (n = 2), blaNDM-1 (n = 3), and blaVIM-2 (n = 2). All of the remaining 27 isolates were negative according to the Carba NP test, mCIM, and multiplex PCR. The specificities of both assays were 100%. The sensitivity of the Xpert Carba-R assay was as low as 53.8% and that of the NG-Test CARBA5 was 92.3% because the former failed to detect all isolates with blaIMP-19 (n = 12) and the latter failed to detect isolates with blaIMP-66 (n = 2). Both assays can easily be performed in less than 5 min. ConclusionsThe NG-Test CARBA5 assay was superior with regard to assay time and cost per sample. We propose the use of the NG-Test CARBA5 assay in clinical laboratories where IMP-type carbapenemases are endemic.

Blood Stream Infections caused by Non-Fermenting Gram Negative Bacilli, Clinical Correlation, MIC for Colistin, Gene Detection

To study the risk factors and outcome of blood stream infection caused by non-fermenting gram negative bacilli (NFGNB) and their pattern of antibiotic susceptibility and genes. We included sepsis cases with blood culture positive for NFGNB. MIC for colistin was determined by broth microdilution method. Multiplex PCR was used to detect BlaIMP, BlaVIM, BlaKPC, BlaNDM-1 genes in cephalosporin and carbapenems resistant Acinetobacter spp. isolates. Out of 4,664 cases of sepsis, 50 (1.07%) were positive for NFGNB. Acinetobacter spp. 29 (58%) was the predominant isolate, of which 16 (55.17%) isolates were resistant to cephalosporins and carbapenems. We detected BlaKPC and BlaNDM-1 genes in two of these isolates. We did not detect BlaIMP, BlaVIM, BlaKPC and BlaNDM-1 genes in any other NFGNB isolates. Majority of the strains of Pseudomonas spp. showed sensitivity to all the antibiotics tested. NFGNB sepsis patients with respiratory illness correlated well with fatal outcome (p &lt;0.05; OR 21). More numbers of Acinetobacter spp. sepsis cases had fatal outcome (p &lt;0.05; OR 12.83). NFGNB sepsis patients with respiratory illness and those which yielded Acinetobacter spp. correlated positively with fatal outcome. We detected BlaKPC and BlaNDM-1 genes in two strains of drug resistant Acinetobacter spp.

IDENTIFICATION AND CHARACTERIZATION OF NONFERMENTATIVE GRAM NEGATIVE BACILLI FROM VARIOUS CLINICAL SAMPLES IN A TERTIARY CARE HOSPITAL, JAIPUR.

Background: Non fermentative gram negative bacilli that were considered to be contaminants in the past have now emerged as important health care associated pathogens.&#x0D; Aim: This study was undertaken to identify and characterize Nonfermenters isolated from various clinical samples.&#x0D; Material and Methods: Present study was conducted in the department of Microbiology, National Institute of Medical Sciences (NIMS) Medical College and hospital, Jaipur from July 2013 to July 2014. A total 150 strains of Nonfermenters were isolated from 1200 various non repetitive clinical samples. The samples were processed and Non fermentative gram negative bacilli (NFGNB) identified as far as possible up to species level as per standard protocols.&#x0D; Results: In the present study, 12.50% of incidence / isolation rate of Nonfermenters in various clinical samples was found. Out of 150 strains of Nonfermenter, Pseudomonas aeruginosa was the most common isolate 134 (89.33%) followed by Acinetobacter baumannii 16 (10.67%). 89 (59.33%) NFGNB were isolated from males and 61 (40.67%) were from females. They were mainly isolated from age group 21-30 Years. Higher rate of isolation of NFGNB were 85 (56.67%) from IPD and 38 (25.33%) from ICU patients. Among all clinical samples Pus and Wound Discharge yield maximum isolates of NFGNB i.e. 54 (36%) followed by Sputum 39 (26.0%).&#x0D; Conclusion: NFGNB should not be ignored as mere contaminant but correlate clinically for its pathogenic potential and identified using standard protocol so as to institute appropriate and timely antibiotic coverage&#x0D; Keywords: Identification, Nonfermenter, Pseudomonas, Acinetobacter

Hospital-Acquired Pneumonia in a Multipurpose Intensive Care Unit: One-Year Prospective Study.

Hospital-acquired pneumonia continues to be a frequent complication in the intensive care unit and an important causeof admission in the intensive care unit. The aim of our study was to evaluate the demography, incidence, risk factors, causative bacterialpathogens and outcome of all episodes of Hospital-acquired pneumonia in our unit. Prospective observational study, at a tertiary university hospital during one year (2014) including all the casesof hospital-acquired pneumonia in the intensive care unit. Sixty patients were identified with pneumonia. Thirty-five (58.3%) had an intensive care unit acquired pneumonia, correspondingto 6.9 cases/1000 intubation-days. Antibiotic treatment in the previous 30 days was present in 75% of the cases. The incidence ofStaphylococcus aureus, Pseudomonas aeruginosa and Acinetobacter baumannii was 26.2%, 20.0% and 9.2%, respectively. Patientswith late-onset hospital-acquired pneumonia (≥ 7 days) showed higher frequency of non-fermenting Gram-negative bacilli isolates,and methicillin-resistant S. aureus. Combination therapy was performed in 67.0%, and de-escalation in 18.3%. The mortality rate was18.3%. The adjusted odds ratio for intensive care unit mortality in the group of patients with non-intensive care unit acquired pneumoniawas 5.2 (95% CI of 1.02 - 22.10; p = 0.046). The knowledge of local bacterial flora and resistance patterns is of crucial importance and strongly recommended. Thisevidence increases the probability of success of empiric antibiotic therapy. S. aureus was the predominant causative agent of nosocomial pneumonia. The most frequent risk factor identified forinfection with multidrug-resistant organisms was previous treatment with antibiotics. Multidrug-resistant organisms were present in 45%of documented hospital-acquired pneumonias. In admitted patients with non-intensive care unit acquired pneumonia, the intensive careunit mortality rate was nearly five times higher compared to intensive care unit acquired pneumonia.

Are we missing the diagnosis of disseminated melioidosis? An unusual presentation of melioidosis with prostatic abscess

Melioidosis, an emerging infectious disease in India is well known for its protean clinical manifestations. Definitive diagnosis can be made by isolation of non-fermentative Gram-negative bacilli from clinical specimens and identification of the isolate at the species level. We report a case of disseminated melioidosis with lymphadenitis and prostatic abscess. Burkholderia pseudomallei was isolated from bone marrow, pus aspirate, blood and urine, and the patient responded well to the treatment.

MALDI-TOF mass spectrometry: An emerging tool for unequivocal identification of non-fermenting Gram-negative bacilli.

Background & objectives:Matrix-assisted laser desorption ionization-time-of-flight mass spectrometry (MALDI-TOF MS) has been instrumental in revolutionizing microbiological identification, especially in high-throughput laboratories. It has enabled the identification of organisms like non-fermenting Gram-negative bacilli (NFGNB), which has been a challenging task using conventional methods alone. In this study an attempt was made to validate MALDI-TOF MS for the identification of clinical isolates of each of the three most common NFGNB, other than Pseudomonas spp., taking molecular methods as the gold standard.Methods:One hundred and fifty clinical isolates of NFGNB, confirmed by molecular methods such as Acinetobacter baumannii[oxa-51 polymerase chain reaction (PCR)], Burkholderia cepacia complex (expanded multilocus sequence typing) and Stenotrophomonas maltophilia (species-specific PCR), were taken. Isolated colonies from fresh cultures of all 150 isolates were smeared onto ground steel plate, with and without formic acid extraction step. The identification was carried out using MALDI-TOF MS Biotyper database.Results:A concordance of 100 and 73.33 per cent was found between the molecular techniques and MALDI-TOF MS system in the identification of these isolates up to genus and species levels, respectively. Using a cut-off of 1.9 for reliable identification, rate of species identification rose to 82.66 per cent. Principal component analysis dendrogram and cluster analysis further increased discrimination of isolates.Interpretation & conclusions:Our findings showed MALDI-TOF MS-based identification of NFGNB as a good, robust method for high-throughput laboratories.

Prevalence and antimicrobial susceptibility of non-fermenting Gram-negative bacilli isolated from clinical samples at a tertiary care hospital.

We compared the prevalence and antimicrobial susceptibility of non-fermenting gram-negative bacilli (NFGNB) isolated from clinical samples at a Brazilian tertiary care hospital in 2008 and 2013. Collected data included patient's name, age, sex, inpatient unit, laboratory record number, type of biological material, culture test result, and antimicrobial susceptibility of isolated strains. Out of 19,112 culture tests analyzed, 926 (4.8%) were positive for NFGNB. Among these, 45.2% were metallo-beta-lactamase (MBL) producing strains. Between 2008 and 2013, the number of MBL-producing NFGNB isolates increased by 21.5%, which was accompanied by a consequent reduction in susceptibility to antimicrobials.

Prevalence of Carbapenem Resistant Non-Fermenting Gram Negative Bacterial Infection and Identification of Carbapenemase Producing NFGNB Isolates by Simple Phenotypic Tests.

Non-Fermenting Gram negative bacilli (NFGNB) are emerging multi-drug resistant pathogens causing nosocomial infections. In recent years, carbapenem resistance in NFGNB has increased due to a variety of drug resistance mechanisms, the most common being production of carbapenemases. To detect carbapenemase and metallo-β-lactamase (MBL) production in NFGNBs by four phenotypic tests and to compare the various phenotypic methods for detection of carbapenemase and MBL production in nosocomial NFGNB isolates. It is a cross sectional study carried out in the department of Microbiology, Chennai Medical College Hospital and Research Center, Irungalur, Trichy between January 2015 and December 2015. Out of the 598 NFGNB isolated from all the 5402 heterogenous clinical samples that were processed, 52 (8.7%) NFGNB showed resistance or intermediate sensitivity to meropenem as tested by disc diffusion assay. All the 52 isolates were subjected to four different phenotypic tests for carbapenemase and MBL detection, which included Modified Hodge Test (MHT), Meropenem-EDTA Disc Synergy (EDS) test, Meropenem-EDTA Combined Disc Test (CDT) and Growth on CHROMagar KPC. Among the 52 isolates, 29 (55.77%) were MHT positive and 49 (94.23%) were positive for growth on CHROMEagar KPC which were identified as carbapenemase producers. 44 (84.61%) were EDS positive and 46 (88.46%) were CDT positive which were identified as metallo-β-lactamase producers. The presence of these resistant bugs strongly suggests the need to prevent their further spread by implementation of strict infection control measures and regular surveillance to check their outcome. Growth on CHROMagar KPC is the test that has picked up more number of carbapenem resistant isolates as carbapenemase and metallo-β-lactamase producers among the four tests. It is also cheap and easy to perform, making it the most reliable test for routine screening of carbapenemase and MBL producers in clinical laboratories.

Antibiotic susceptibility profiles of non-fermenting gram-negative Bacilli at a Tertiary Care Hospital in Patiala, India.

Non-fermenting Gram-negative bacilli (NFGNB) have emerged as a major cause of healthcare-associated infections and are innately resistant to many antibiotics. The aim of this study was to determine the prevalence of NFGNB isolated from various clinical specimens and evaluate their antimicrobial susceptibility profiles. This retrospective study was done at our Department of Microbiology from December 2015 to December 2016. NFGNB were isolated from a variety of clinical specimens, plated on blood agar and MacConkey agar and incubated at 37°C for 18-24 h under aerobic conditions. Appropriate biochemical tests were done to identify the organisms isolated. Antibiotic susceptibility test was performed using the modified Kirby-Bauer disc diffusion method using commercially available discs on Mueller-Hinton agar. Data was analyzed using SPSS IBM version 20. Out of 19065 clinical samples, cultures were positive in 1854 samples. Out of 1854 culture-positive samples, 216 (11.6%) yielded NFGNB. Pseudomonas aeruginosa was the most common NFGNB, isolated in 190/216 (87.96%) samples, followed by Acinetobacter baumannii (17/216, 7.87%). Overall, most of the NFGNB isolates were susceptible to polymyxin B (88.4%), imipenem (82.9%) and cefoperazone + sulbactam (50.9%), and a total of 11 (64.71%) multidrug-resistant A. baumannii (MDRAB) strains were isolated in the study. Our study showed a significantly high prevalence of NFGNB. Isolation of multidrug-resistant P. aeruginosa and MDRAB in the present study raises the concern of rapidly emerging antibiotic resistance in this group of bacteria in our region.

Presence of metallo-beta-lactamases (MBL), extended-spectrum beta-lactamase (ESBL) & AmpC positive non-fermenting Gram-negative bacilli among Intensive Care Unit patients with special reference to molecular detection of blaCTX-M & blaAmpC genes.

Background & objectives:Non-fermenting Gram-negative bacilli (NFGNB) including Pseudomonas aeruginosa and Acinetobacter baumannii have been implicated in a variety of infections, particularly in the Intensive Care Units (ICUs). This study was aimed to overview the burden of multidrug-resistant NFGNB causing infections in ICU and also to assess the occurrence of extended-spectrum beta-lactamases (ESBLs), AmpC and metallo-beta-lactamases (MBLs) among these isolates.Methods:Bacterial culture, identification and antibiotic susceptibility were carried out. ESBLs and AmpC were detected both phenotypically and genotypically. MBL was detected by modified Hodge and imipenem-ethylenediaminetetraacetic acid double-disc synergy test.Results:NFGNB represented 45 (37%) of total 121 Gram negative isolates. Multidrug resistance was observed in 66.9 per cent and 72.5 per cent isolates of P. aeruginosa and A. baumannii, respectively. Detection by phenotypic methods showed presence of ESBL, AmpC and MBL in 21.4, 51.1 and 21.4 per cent isolates, respectively. When detected genotypically by polymerase chain reaction, ESBL and AmpC were detected in 21.4 and 41.4 per cent of NFGNB isolates, respectively. BlaCTX-M (21.4%) was the most prevalent gene responsible for ESBL production.Interpretation & conclusions:Most of the NFGNB isolated from ICU patients were multidrug-resistant and producers of ESBL, AmpC and MBL. A regular surveillance is required to detect ESBL, AmpC and MBL producers, especially in ICU patients.