Gram-negative Fermentative Bacteria Research Articles

Comparison between vacuum and modified-atmosphere packaging on dynamic analysis of flavor properties and microbial communities in fresh-cut potatoes (Solanum tuberosum L.)

Fresh-cut potatoes are prone to browning and quality deterioration during storage, which leads to a short shelf life. In the present study, we investigated the sensory quality attributes, flavor profiles, and bacterial community composition of fresh-cut potato cubes stored at 4 °C for 18 days in vacuum packaging and 30 % CO2/70 % N2 modified-atmosphere packaging. In addition, a correlation analysis of volatile organic compounds and bacterial taxa was performed. In total, 26 types of volatile organic compounds were identified; aldehydes were considered as the main contributors to the odor, and the off-flavor was mainly described as a mixture of oily, spicy, and beany flavors. The dominant bacteria in all packaged potatoes were fermentative gram-negative bacteria Alcaligenaceae and Sphaerotilus. Notably, compared with vacuum packaging, modified-atmosphere packaging inhibited the generation and development of undesirable flavors and maintained the sensory profile of fresh-cut potatoes in a better manner during storage.

A spectrum of non-spore-forming fermentative and non-fermentative Gram-negative bacteria: multi-drug resistance, extended-spectrum beta-lactamase, and carbapenemase production

BackgroundIn developing countries, the co-existence of a high burden of infectious diseases caused by Gram-negative bacteria and the rapid increase and spread of multidrug-resistant bacteria have become a serious health threat.ObjectiveProfiling of Gram-negative bacteria and determining the magnitude of their antimicrobial resistance among patients.ResultsA total of 175 non-spore-forming Gram-negative bacteria were isolated from 873 different clinical samples. Of a total of 175 bacteria, 154 (88%) were fermentative Gram-negative bacteria, while 21 (12%) were non-fermentative Gram-negative bacteria. E. coli with a frequency of 58.3% and K. pneumoniae with a frequency of 18.3% were the predominant fermentative Gram-negative bacteria, while P. aeruginosa 9 (5.1%) and A. baumannii 6 (3.4%) were the predominant non-fermentative Gram-negative bacteria. The highest percentage level of antibiotic resistance was seen against ampicillin (86%), and the lowest against meropenem (9.8). About 49 (28%) Gram-negative bacilli were positive for ESBLase. The overall prevalence rate of MDR bacteria was 80.5%, of which 100% of A. baumannii, 90.6% of K. pneumonia. Sixteen isolates were resistant to meropenem, out of which 11 tested for carbapenemase production. Five of the nine were metallo-lactamase producers, with the remaining four being serine carbapenemase producers.ConclusionThe prevalence of Gram-negative bacterial infection was found to be 20%, with a significant proportion (80.0%) due to fermentative Gram-negative bacteria and the remaining 20% due to non-fermentative Gram-negative bacteria. The study has also demonstrated a high prevalence rate of MDR, ESBLase, and carbapenemase-producing Gram-negative bacteria. Antimicrobial resistance of Gram-negative bacteria should be monitored on a regular basis, and an effective infection control program should be implemented.

Quarantine and Antibiotic Susceptibility of Enterobacteriaceae Strains and other Gram-Negative Bacteria in Dairy Sweetmeat Milk (Doodh) Peda

The present study aimed to assess the prevalence and isolation of Enterobacteriaceae strains and other gram-negative bacteria of milk (doodh) peda-a traditional milk product of India. Bacteria of the family Enterobacteriaceae are the indicator organisms that provide evidence of poor hygiene, inadequate processing or post-process contamination of foods. A total of 25 peda samples were collected from different places in the Mysuru district to evaluate the prevalence of Enterobacteriaceae. Seventeen gram-negative fermentative bacteria of clinical significance were detected and isolated. API 20E biochemical identification syatem and other associated biochemical tests are used as a supportive tool to identify gram-positive and gram-negative bacteria. Our outcomes indicate that milk peda contaminated with the Enterobacteriaceae like Enterobacter cloacae, Yersinia bercovieri, Yersinia rohdei, Raoutlella terigena, Acinetobacter lwoffii, Pantoea agglomerans PA2, Klebsiella pneumoniae subsp pneumoniae, Leclericia adecarboxylata, Photorhabdus nematophilus, Enterobacter gergoviae, Acinetobacter baumannii/calcoacetius, Cronobacter sakazaki (Enterobacter sakazaki). Further, the antimicrobial resistance of these Enterobacteriaceae groups was also investigated against 20 antibiotics by the disc diffusion assay method. All isolates revealed susceptibility to the fluoroquinolones and aminoglycosides. But resistance to the nitrofurantoin (70.59 %), augmentin (52.94%), and cefpodoxime (47.06%) antibiotics. Our finding was the first report of the prevalence and detection of E. gergoviae in a food sample (milk peda) and examined for antibiotic resistance.

Phenotypic detection of Metallo-β-Lactamase in Imipenem-Resistant Pseudomonas aeruginosa and Stenotrophomonas maltophilia at Schiphra Hospital of Ouagadougou in Burkina Faso

Background: Epidemic of carbapenemase-producing bacteria has become worldwide. Thus, during the last decade, the prevalence of carbapenem-resistant Enterobacteriaceae and non fermentative Gram-negative bacteria in human patients have increased. Carbapenemase-producing bacteria are usually multidrug resistant. Therefore, early recognition of carbapenemase producers is critical to prevent their spread. Objectives: The aim of this study was to contribute establishing the prevalence of isolates producing Metallo-β-Lactamase isolated from patients admitted to Schiphra Hospital of Ouagadougou. Methods: Susceptibility of bacteria to antimicrobial agents was evaluated by disc diffusion method using imipenem as screening antibiotic. The combination of imipenem-EDTA was used after detection the resistance to imipenem. Results: A total of 52 isolates resisting one of the third generation cephalosporins were collected. Five isolates showed an intermediary resistance to imipenem (9.61%). Two isolates were resistant to imipenem-EDTA (3.85%). The test of imipenem-EDTA was done to confirm to production of Metallo-β-Lactamase. The hydrolysis of bacterial extract by meropenem was confirmed by production with a kinetic activity at spectrophotometer V0=4.77x10–5µM/min for Pseudomonas aeruginosa and V0=1.183x10-4 µM/min for Stenotrophomonas maltophilia. Conclusion: This study showed that bacterial resistances by production to metallo-β-lactamases are a reality in Burkina Faso.

Surgical Site Infections with Predominance of Multidrug Resistant in Benin: A Multicenter Study

Background: Surgical site infections remain common and widespread; they contribute to increasing antimicrobial resistance among the etiological agents. Antimicrobial resistance is the ability of a microorganism like bacteria to stop an antimicrobial from working against it. This study was conducted to determine the spectrum of bacterial isolates from surgical site infections and their susceptibility patterns. A secondary outcome was to compare bacterial identification by a local lab and a European one. Methods: This descriptive cross-sectional study was conducted between January and August 2019 in 6 public hospitals in Benin. Pus specimens were processed using standard microbiological procedures, and identification was performed using the analytical profile index (API). Antimicrobial susceptibility testing was performed in Benin following the modified Kirby-Bauer disk-diffusion technique and was confirmed in Belgium by MALDI-TOF mass spectrometry. A second antimicrobial susceptibility test was performed using BD Phoenix automated microbiology system (Becton Dickinson). Clinical data of enrolled patients were obtained from hospital records. Results: The mean age of patients was 32 ± 11 years (range, 18–76). The median time for surgical site infections was 9 postoperative days. Of the 229 patients from whom wound swabs were collected, 195 (85.15%) showed positive aerobic bacterial growth. In total, 164 pathogenic bacteria were isolated, including 41 gram-positive organisms (25%), 78 gram-negative fermentative bacteria (47.5%), and 45 gram-negative nonfermentative bacteria (27.5%). We observed 3 discrepancies between API technique and MALDI-TOF. Two Klebsiella pneumoniae and 1 Pseudomonas spp (API) versus, respectively, Klebsiella varicola and Pseudomonas mendocina (MALDI-TOF). The most prevalent bacterial species were E. coli (31%), followed by S. aureus (25%), Pseudomonas aeruginosa (18%), and Klebsiella pneumoniae (11%). Of the 41 S. aureus, 26 (63,41%) were methicillin-resistant Staphylococcus aureus (MRSA), and 3 of these were carrying both MRSA and induced clindamycin resistance (ICR). Extended-spectrum β-lactamase (ESBL)–producing Enterobacteriaceae were observed in 60 of 78 isolates tested (77%). All of 2 Morganella morgannii and 89% of K. pneumoniae were ESBL producers. Conclusions: Among S. aureus, 2 of 3 were MRSA, whereas almost K. pneumoniae and E. coli were ESBL producers. Three strains are pan–drug resistant in nonfermentative bacteria, and no isolate was susceptible to all antibiotics. These findings are of high interest for better management of patients and control of antimicrobial resistance in Benin.Funding: This study was supported by Académie de Recherche pour l’Enseignement Supérieur (ARES).Disclosures: None

Prevalence of Diabetic foot ulcer infections associated with Gram negative bacteria with special reference to drug resistant isolates

Introduction: Diabetic Mellitus type 2 is most common causes are foot ulcer; Infections include abscess, necrotizing, fasciitis, gangrene, arthritis, tendonitis, cellulitis, osteomyelitis and eventually lead to the development of limb amputation.Aims and Objectives: This study carried out to determine the patterns of infection in diabetic foot ulcers with special reference to the susceptibility and drug resistant isolates.Materials and Methods: Samples were collected from 199 diabetic foot ulcers patients by using pus swab, tissue, and exudates in sterile containers and processed to using standard microbiological techniques.Results: A total of 441 bacterial isolates were obtained from 199 patients with diabetic foot ulcers. A maximum number of patients were in the age group of 45 to 64 years and male predominant compared to female. Most of the isolates recovered according to Wagner classification system in DFU (Diabetic foot ulcer) >4cm2, >7.0 HbA1C and blood urea >30 mg/dl and serum creatinine >1.3mg/dl. 55% isolates of non-lactose fermenting Gram negative bacteria were more prevalent than 45% isolates of lactose fermenting Gram negative bacteria. The most commonly found isolate was Pseudomonas aeruginosa (39.6%), Escherichia coli (17.46%), Acinetobacter species (15.41%), Proteus species (12.47%), and Klebsiella species (9.75%) respectively. Antimicrobial susceptibility of the Gram negative bacteria was also studied. ESBL producing most common bacteria was Klebsiella species and Citrobacter species in this study than Escherichia coli and Enterobacter species.Conclusion: This study shows NLF predominant than LF GNB among the isolates from the diabetic foot ulcers. Antimicrobial susceptibility result of this study suggests that pathogens having susceptible to Imipenem and Piperacillin/ tazobactam were sensitive against LF, NLF-GNB and also ESBL producing bacteria. Colistin is the drug of choice multi-drug resistant (MDR) pathogens. Surveillance and monitoring on the antibiotic susceptibility pattern of the isolates will be helpful in determining the drugs for the empirical treatment of diabetic ulcers.

Non fermentative Gram negative bacteria in Hospital Water Sources: prevalence and distribution of antibiotic resistant strains

The environment is a broad reservoir of antibiotic resistant organisms. Bacteria in natural environments likely serve as a reservoir of resistance genes that can be transmitted to human pathogens. Antibiotic resistance in hospital environment is growing concern, especially among non fermenting Gram-negative bacteria (NFGNB), being the most widespread cause of nosocomial infections. Our study provides detailed description of the distribution of NFGNB collected in water sources from different wards of a tertiary …

Mutation ofgyrA andparC in clinical isolates ofAcinetobacter baumannii and its relationship with antimicrobial drugs resistance in Taiwan

Acinetobacter baumannii is a species of non fermentative Gram-negative bacteria commonly found in water and soil. This organism was susceptible to most antibiotics in the 1970s. It has now become a major cause of hospital-acquired infections worldwide due to its remarkable propensity to rapidly acquire resistance determinants to a wide range of antibacterial agents. Herein we have determined the mutation frequency of two hot spot residue 83 in gyrA of gyrase and residue 80 in parC of topoisomerase IV and performed a comparative screen the drug resistance ability in 128 clinical isolates ofAcinetobacter baumannii in Taiwan region. Low frequency of mutation was found (11.7%, 11.7%, and 10.2% ingyrA, parC, or both, respectively). Mutation of these sites was not correlated with drug resistance. Our study suggested that mutation ofgyrA andparC may play a minor role in quinolone resistance and other mechanisms may contribute to the drug resistance ofA. Baumannii.

Evaluation of the autoSCAN-W/A rapid system for identification and susceptibility testing of gram-negative fermentative bacilli.

The autoSCAN-Walk-Away (W/A) system for identification and susceptibility testing was evaluated for 400 gram-negative fermentative bacteria by using the API 20E (366 isolates) and/or tube biochemical tests as the reference identification system and a frozen microdilution MIC tray system for susceptibility testing. The W/A system performed well for identification of this group of organisms representing 14 genera and 30 species, showing a sensitivity of 96% and results available in 2 h. Of the 16 misidentifications, 6 were with Serratia liquefaciens. A total of 63 isolates (17%) required further tests to complete the identification, compared with 106 (29%) of the isolates which required additional tests for the API 20E identification. Approximately half (32) of the additional tests with the W/A system were required in order to separate Citrobacter diversus from C. amalonaticus. For susceptibility determinations, the W/A system demonstrated an overall agreement of 93% (4,102 determinations) with 40 major errors (0.98%). However, of the 906 resistant organism-drug combinations in the study, there were 115 very major errors, for a false-susceptibility rate of 12.7% of the resistance determinations. Among these very major errors, 80% occurred with piperacillin and the cephalosporins. The W/A system completed the MIC determinations in 7 h; however, the difficulty in detecting resistance with some antimicrobial agents limited the advantages of the rapid susceptibility testing.

Susceptibility of 461 Nosocomial Gram-Negative Pathogens to Enoxacin and Other Antibiotics

The in vitro activity of enoxacin against 461 strains of Gram-negative aerobic bacteria, recently isolated from clinical specimens, was assessed by broth dilution techniques which determined minimum inhibitory concentrations (MICs). The sensitivity of all species of Gram-negative fermentative bacteria ranged from 66.6% (Kluyvera ascorbata and Morganella morganii) to 100% (Hafnia alvei) [MIC range 0.25 to 64 mg/L]. For Gram-negative nonfermentative species, the overall susceptibility of isolates ranged from 53% for Pseudomonas aeruginosa to 100% for Alcaligenes faecalis and Aeromonas hydrophila. The percentages of resistant strains to enoxacin were evaluated in comparison with piperacillin, ceftazidime, gentamicin, netilmicin and amoxicillin using a standard agar diffusion technique. Although enoxacin demonstrated some inter-species variability, in actuality it showed similar overall activity to that of ceftazidime, gentamicin and netilmicin, but was more active overall than piperacillin and amoxicillin.

Evaluation of a small “Conventional” identification system for fermentative gramnegative rods using a computerized data base

A small “conventional” identification system consisting of six tubed media totalling eleven reactions was used to identify 467 strains of Enterobacteriaceae, 15 strains of Aeromonas sp., and 3 strains of Plesiomonas shigelloides. The system identified 371 strains (76.5%) correctly to maximum identification (species or genus) level and an additional 13 strains (2.7%) to genus level where species level identification would have been possible. Ninety strains (18.6%) were not identified. Only 11 strains(2.3%) were misidentified. The system is inexpensive compared with commercial systems and can be used for primary identification of fermentative gramnegative bacteria in a clinical microbiology laboratory. It comes with a computerized data base in the form of an identification manual.

In vitro antibacterial activity of three new quinolone derivatives: rosoxacin, norfloxacin, pefloxacin.

The in vitro activities of rosoxacin, norfloxacin and pefloxacin against 480 bacterial strains were studied. MIC90s of norfloxacin and pefloxacin were less than or equal to 2 micrograms/ml for E. coli, Klebsiella sp., E. cloacae, Proteus sp. and Staphylococcus sp., less than or equal to 8 micrograms/ml for C. freundii, Providencia sp., S. faecalis, and non fermentative Gram-negative bacteria, while they were of 32 micrograms/ml for S. marcescens. Rosoxacin exhibited a lower activity with MIC90s 2 to 16 fold higher against Enterobacteriaceae and P. aeruginosa. Ninety per cent of isolates resistant to nalidixic-acid appeared susceptible to norfloxacin and pefloxacin with MIC less than or equal to 16 micrograms/ml.

Role of pH, lactate, and anaerobiosis in controlling the growth of some fermentative Gram-negative bacteria on beef.

At 5 degrees C four strains of fermentative, gram-negative bacteria (Serratia liquefaciens, Yersinia enterocolitica, Enterobacter cloacae, and Aeromonas hydrophila) grew aerobically and anaerobically on adipose tissue removed from beef muscle of low pH (5.4 to 5.6). All four strains also grew aerobically and anaerobically on muscle tissue of high pH (6.0 to 6.3). However, none of the four grew anaerobically on beef muscle of low pH, and the aeromonad strain also failed to grow aerobically on such muscle. Growth of S. liquefaciens and E.cloacae on vacuum-packaged beef muscle was dependent on the pH of the tissue and the oxygen transmission rate of the packaging film. Although the four strains grew in broth buffered at pH 5.55, L-lactate, at the concentration found in muscle of low pH (ca. 100 mM), prevented anaerobic growth of all four isolates and prevented the aerobic growth of th aeromonad. At pH 6.1 in buffered broth, the concentration of L-lactate occurring in muscle of high pH did not prevent aerobic or anaerobic growth of any of the strains.

Evaluation of the Minitek system for identification of nonfermentative and nonenteric fermentative Gram-negative bacteria.

The Minitek identification system (MT) was compared with a conventional testing battery for the characterization of 735 isolates which included 57 species and groups of nonfermentative (NF) and nonenteric fermentative (NEF) gram-negative bacteria. The MT correctly identified 585 of 616 NF (94,96%) and 115 of 119 NEF (96.65%) bacteria and 700 of 735 strains (95.24%) overall. A total of 31 NF and NEF (4.22%) bacteria were misidentified, and no identification was determined for four strains (0.69%). All strains of Acinetobacter anitratus, Pseudomonas maltophilia, P. fluroescens, and P. putida and all but one strain of P. aeruginosa were correctly identified. The most frequently misidentified taxa were CDC group Va-1, P. pickettii (Va-2), P. mendocina, and Moraxella urethralis (M-4). Supplemental tests were needed for the complete identification of 214 strains (29.11%). An average of 1.54 supplemental tests were used with each of these strains. A total of 134 strains (18.23%) had their identification delayed by 1 day due to supplemental testing. We recommend the use of the 42 degree C growth test with the MT. When used in accord with the manufacturer's instructions and with the MT code book the MT was found to be a valuable system for the identification of a wide variety of common and infrequently encountered NF and NEF bacteria.