EFFECT OF ANAEROBIOSIS ON THE EMERGENCE OF STREPTOMYCIN-RESISTANT BACTERIA

1961 ◽  
Vol 7 (3) ◽  
pp. 411-422 ◽  
Author(s):  
H. Farkas-Himsley

This paper deals with the increase in numbers of streptomycin-resistant mutants of V. comma and E. coli B in a so-called streptomycin-sensitive population, when grown under anaerobic conditions. This increase is demonstrated in presence and even in absence of SM. Experiments of a qualitative and quantitative nature are described and a statistical evaluation of the results is given. A relation between the degree of anaerobiosis and SM resistance is demonstrated and the time required for streptomycin resistance to become apparent is shown.Former observations of SM inactivation under anaerobic conditions are discussed in view of the present findings, and a different interpretation suggested.

2019 ◽  
Author(s):  
Elsa Hansen ◽  
Jason Karslake ◽  
Robert J. Woods ◽  
Andrew F. Read ◽  
Kevin B. Wood

AbstractStandard infectious disease practice calls for aggressive drug treatment that rapidly eliminates the pathogen population before resistance can emerge. When resistance is absent, this elimination strategy can lead to complete cure. However, it also removes drug-sensitive cells as quickly as possible, removing competitive barriers that may slow the growth of resistant cells. In contrast to the elimination strategy, the containment strategy aims to maintain the maximum tolerable number of pathogens, exploiting competitive suppression to achieve chronic control. Here we combine in vitro experiments in computer-controlled bioreactors with mathematical modeling to investigate whether containment strategies can delay failure of antibiotic treatment regimens. To do so, we measured the “escape time” required for drug-resistant E. coli populations to eclipse a threshold density maintained by adaptive antibiotic dosing. Populations containing only resistant cells rapidly escape containment, but we found that matched populations with the maximum possible number of sensitive cells could be contained for significantly longer. The increase in escape time occurs only when the threshold density–the acceptable bacterial burden–is sufficiently high, an effect that mathematical models attribute to increased competition. The findings provide decisive experimental confirmation that maintaining the maximum number of sensitive cells can be used to contain resistance when the size of the population is sufficiently large.


2019 ◽  
pp. 48-54
Author(s):  
Duy Binh Nguyen ◽  
Trung Tien Phan ◽  
Trong Hanh Hoang ◽  
Van Tuan Mai ◽  
Xuan Chuong Tran

Sepsis is a serious bacterial infection. The main treatment is using antibiotics. However, the rate of antibiotic resistance is very high and this resistance is related to the outcome of treatment. Objectives: To evaluate the situation of antibiotic resistance of some isolated bacteria in sepsis patients treated at Hue Central Hospital; to evaluate the relationship of antibiotic resistance to the treatment results in patients with sepsis. Subjects and methods: prospective study of 60 sepsis patients diagnosed according to the criteria of the 3rd International Consensus-Sepsis 3 and its susceptibility patterns from April 2017 to August 2018. Results and Conclusions: The current agents of sepsis are mainly S. suis, Burkhoderiae spp. and E. coli. E. coli is resistant to cephalosporins 3rd, 4th generation and quinolone group is over 75%; resistance to imipenem 11.1%; the ESBL rate is 60%. S. suis resistant to ampicilline 11.1%; no resistance has been recorded to ceftriaxone and vancomycine. Resistance of Burkholderiae spp. to cefepime and amoxicillin/clavulanic acid was 42.9% and 55.6%, resistant to imipenem and meropenem is 20%, resistance to ceftazidime was not recorded. The deaths were mostly dued to E. coli and K. pneumoniae. The mortality for patients infected with antibiotic-resistant bacteria are higher than for sensitive groups. Key words: Sepsis, bacterial infection, antibiotics


Antibiotics ◽  
2021 ◽  
Vol 10 (4) ◽  
pp. 466
Author(s):  
Herbert Galler ◽  
Josefa Luxner ◽  
Christian Petternel ◽  
Franz F. Reinthaler ◽  
Juliana Habib ◽  
...  

In recent years, antibiotic-resistant bacteria with an impact on human health, such as extended spectrum β-lactamase (ESBL)-containing Enterobacteriaceae, methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant Enterococci (VRE), have become more common in food. This is due to the use of antibiotics in animal husbandry, which leads to the promotion of antibiotic resistance and thus also makes food a source of such resistant bacteria. Most studies dealing with this issue usually focus on the animals or processed food products to examine the antibiotic resistant bacteria. This study investigated the intestine as another main habitat besides the skin for multiresistant bacteria. For this purpose, faeces samples were taken directly from the intestines of swine (n = 71) and broiler (n = 100) during the slaughter process and analysed. All samples were from animals fed in Austria and slaughtered in Austrian slaughterhouses for food production. The samples were examined for the presence of ESBL-producing Enterobacteriaceae, MRSA, MRCoNS and VRE. The resistance genes of the isolated bacteria were detected and sequenced by PCR. Phenotypic ESBL-producing Escherichia coli could be isolated in 10% of broiler casings (10 out of 100) and 43.6% of swine casings (31 out of 71). In line with previous studies, the results of this study showed that CTX-M-1 was the dominant ESBL produced by E. coli from swine (n = 25, 83.3%) and SHV-12 from broilers (n = 13, 81.3%). Overall, the frequency of positive samples with multidrug-resistant bacteria was lower than in most comparable studies focusing on meat products.


Antibiotics ◽  
2021 ◽  
Vol 10 (7) ◽  
pp. 850
Author(s):  
Shobha Giri ◽  
Vaishnavi Kudva ◽  
Kalidas Shetty ◽  
Veena Shetty

As the global urban populations increase with rapid migration from rural areas, ready-to-eat (RTE) street foods are posing food safety challenges where street foods are prepared with less structured food safety guidelines in small and roadside outlets. The increased presence of extended-spectrum-β-lactamase (ESBL) producing bacteria in street foods is a significant risk for human health because of its epidemiological significance. Escherichia coli and Klebsiella pneumoniae have become important and dangerous foodborne pathogens globally for their relevance to antibiotic resistance. The present study was undertaken to evaluate the potential burden of antibiotic-resistant E. coli and K. pneumoniae contaminating RTE street foods and to assess the microbiological quality of foods in a typical emerging and growing urban suburb of India where RTE street foods are rapidly establishing with public health implications. A total of 100 RTE food samples were collected of which, 22.88% were E. coli and 27.12% K. pneumoniae. The prevalence of ESBL-producing E. coli and K. pneumoniae was 25.42%, isolated mostly from chutneys, salads, paani puri, and chicken. Antimicrobial resistance was observed towards cefepime (72.9%), imipenem (55.9%), cefotaxime (52.5%), and meropenem (16.9%) with 86.44% of the isolates with MAR index above 0.22. Among β-lactamase encoding genes, blaTEM (40.68%) was the most prevalent followed by blaCTX (32.20%) and blaSHV (10.17%). blaNDM gene was detected in 20.34% of the isolates. This study indicated that contaminated RTE street foods present health risks to consumers and there is a high potential of transferring multi-drug-resistant bacteria from foods to humans and from person to person as pathogens or as commensal residents of the human gut leading to challenges for subsequent therapeutic treatments.


Author(s):  
Maria Clara V. M. Starling ◽  
Elizângela P. Costa ◽  
Felipe A. Souza ◽  
Elayne C. Machado ◽  
Juliana Calábria de Araujo ◽  
...  

AbstractThis work investigated an innovative alternative to improve municipal wastewater treatment plant effluent (MWWTP effluent) quality aiming at the removal of contaminants of emerging concern (caffeine, carbendazim, and losartan potassium), and antibiotic-resistant bacteria (ARB), as well as disinfection (E. coli). Persulfate was used as an alternative oxidant in the solar photo-Fenton process (solar/Fe/S2O82−) due to its greater stability in the presence of matrix components. The efficiency of solar/Fe/S2O82− at neutral pH using intermittent iron additions is unprecedented in the literature. At first, solar/Fe/S2O82− was performed in a solar simulator (30 W m−2) leading to more than 60% removal of CECs, and the intermittent iron addition strategy was proved effective. Then, solar/Fe/S2O82− and solar/Fe/H2O2 were compared in semi-pilot scale in a raceway pond reactor (RPR) and a cost analysis was performed. Solar/Fe/S2O82− showed higher efficiencies of removal of target CECs (55%), E. coli (3 log units), and ARB (3 to 4 log units) within 1.9 kJ L−1 of accumulated irradiation compared to solar/Fe/H2O2 (CECs, 49%; E. coli, 2 log units; ARB, 1 to 3 log units in 2.5 kJ L−1). None of the treatments generated acute toxicity upon Allivibrio fischeri. Lower total cost was obtained using S2O82− (0.6 € m−3) compared to H2O2 (1.2 € m−3). Therefore, the iron intermittent addition aligned to the use of persulfate is suitable for MWWTP effluent quality improvement at neutral pH.


2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Kaitlin S. Witherell ◽  
Jason Price ◽  
Ashok D. Bandaranayake ◽  
James Olson ◽  
Douglas R. Call

AbstractMultidrug-resistant bacteria are a growing global concern, and with increasingly prevalent resistance to last line antibiotics such as colistin, it is imperative that alternative treatment options are identified. Herein we investigated the mechanism of action of a novel antimicrobial peptide (CDP-B11) and its effectiveness against multidrug-resistant bacteria including Escherichia coli #0346, which harbors multiple antibiotic-resistance genes, including mobilized colistin resistance gene (mcr-1). Bacterial membrane potential and membrane integrity assays, measured by flow cytometry, were used to test membrane disruption. Bacterial growth inhibition assays and time to kill assays measured the effectiveness of CDP-B11 alone and in combination with colistin against E. coli #0346 and other bacteria. Hemolysis assays were used to quantify the hemolytic effects of CDP-B11 alone and in combination with colistin. Findings show CDP-B11 disrupts the outer membrane of E. coli #0346. CDP-B11 with colistin inhibits the growth of E. coli #0346 at ≥ 10× lower colistin concentrations compared to colistin alone in Mueller–Hinton media and M9 media. Growth is significantly inhibited in other clinically relevant strains, such as Acinetobacter baumannii, Pseudomonas aeruginosa, and Klebsiella pneumoniae. In rich media and minimal media, the drug combination kills bacteria at a lower colistin concentration (1.25 μg/mL) compared to colistin alone (2.5 μg/mL). In minimal media, the combination is bactericidal with killing accelerated by up to 2 h compared to colistin alone. Importantly, no significant red blood hemolysis is evident for CDP-B11 alone or in combination with colistin. The characteristics of CDP-B11 presented here indicate that it can be used as a potential monotherapy or as combination therapy with colistin for the treatment of multidrug-resistant infections, including colistin-resistant infections.


2021 ◽  
Vol 22 (14) ◽  
pp. 7344
Author(s):  
Tsz Tin Yu ◽  
Rajesh Kuppusamy ◽  
Muhammad Yasir ◽  
Md. Musfizur Hassan ◽  
Manjulatha Sara ◽  
...  

The rapid emergence of drug-resistant bacteria is a major global health concern. Antimicrobial peptides (AMPs) and peptidomimetics have arisen as a new class of antibacterial agents in recent years in an attempt to overcome antibiotic resistance. A library of phenylglyoxamide-based small molecular peptidomimetics was synthesised by incorporating an N-alkylsulfonyl hydrophobic group with varying alkyl chain lengths and a hydrophilic cationic group into a glyoxamide core appended to phenyl ring systems. The quaternary ammonium iodide salts 16d and 17c showed excellent minimum inhibitory concentration (MIC) of 4 and 8 μM (2.9 and 5.6 μg/mL) against Staphylococcus aureus, respectively, while the guanidinium hydrochloride salt 34a showed an MIC of 16 μM (8.5 μg/mL) against Escherichia coli. Additionally, the quaternary ammonium iodide salt 17c inhibited 70% S. aureus biofilm formation at 16 μM. It also disrupted 44% of pre-established S. aureus biofilms at 32 μM and 28% of pre-established E. coli biofilms 64 μM, respectively. A cytoplasmic membrane permeability study indicated that the synthesised peptidomimetics acted via disruption and depolarisation of membranes. Moreover, the quaternary ammonium iodide salts 16d and 17c were non-toxic against human cells at their therapeutic dosages against S. aureus.


Antibiotics ◽  
2021 ◽  
Vol 10 (6) ◽  
pp. 744
Author(s):  
Altaf Bandy ◽  
Bilal Tantry

Antimicrobial-resistance in Enterobacterales is a serious concern in Saudi Arabia. The present study retrospectively analyzed the antibiograms of Enterobacterales identified from 1 January 2019 to 31 December 2019 from a referral hospital in the Aljouf region of Saudi Arabia. The revised document of the Centers for Disease Control (CDC) CR-2015 and Magiorakos et al.’s document were used to define carbapenem resistance and classify resistant bacteria, respectively. The association of carbapenem resistance, MDR, and ESBL with various sociodemographic characteristics was assessed by the chi-square test and odds ratios. In total, 617 Enterobacterales were identified. The predominant (n = 533 (86.4%)) isolates consisted of 232 (37.6%), 200 (32.4%), and 101 (16.4%) Escherichia coli, Klebsiella pneumoniae, and Proteus mirabilis, respectively. In general, 432 (81.0%) and 128 (24.0%) isolates were of MDR and ESBL, respectively. The MDR strains were recovered in higher frequency from intensive care units (OR = 3.24 (1.78–5.91); p < 0.01). E. coli and K. pneumoniae resistance rates to imipenem (2.55 (1.21–5.37); p < 0.01) and meropenem (2.18 (1.01–4.67); p < 0.04), respectively, were significantly higher in winter. The data emphasize that MDR isolates among Enterobacterales are highly prevalent. The studied Enterobacterales exhibited seasonal variation in antimicrobial resistance rates towards carbapenems and ESBL activity.


2021 ◽  
Vol 9 (2) ◽  
pp. 326
Author(s):  
Frederick Adzitey ◽  
Nurul Huda ◽  
Amir Husni Mohd Shariff

Meat is an important food source that can provide a significant amount of protein for human development. The occurrence of bacteria that are resistant to antimicrobials in meat poses a public health risk. This study evaluated the occurrence and antimicrobial resistance of E. coli (Escherichia coli) isolated from raw meats, ready-to-eat (RTE) meats and their related samples in Ghana. E. coli was isolated using the USA-FDA Bacteriological Analytical Manual and phenotypic antimicrobial susceptibility test was performed by the disk diffusion method. Of the 200 examined meats and their related samples, 38% were positive for E. coli. Notably, E. coli was highest in raw beef (80%) and lowest in RTE pork (0%). The 45 E. coli isolates were resistant ≥ 50% to amoxicillin, trimethoprim and tetracycline. They were susceptible to azithromycin (87.1%), chloramphenicol (81.3%), imipenem (74.8%), gentamicin (72.0%) and ciprofloxacin (69.5%). A relatively high intermediate resistance of 33.0% was observed for ceftriaxone. E. coli from raw meats, RTE meats, hands of meat sellers and working tools showed some differences and similarities in their phenotypic antimicrobial resistance patterns. Half (51.1%) of the E. coli isolates exhibited multidrug resistance. The E. coli isolates showed twenty-two different resistant patterns, with a multiple antibiotic resistance index of 0.0 to 0.7. The resistant pattern amoxicillin (A, n = 6 isolates) and amoxicillin-trimethoprim (A-TM, n = 6 isolates) were the most common. This study documents that raw meats, RTE meats and their related samples in Ghana are potential sources of antimicrobial-resistant E. coli and pose a risk for the transfer of resistant bacteria to the food chain, environment and humans.


Animals ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 1530
Author(s):  
Amanuel Balemi ◽  
Balako Gumi ◽  
Kebede Amenu ◽  
Sisay Girma ◽  
Muuz Gebru ◽  
...  

A study was carried out from August 2017 to February 2018 on lactating dairy cows, one-humped dromedary camels, and goats to determine mastitis in the Bule Hora and Dugda Dawa districts of in Southern Ethiopia. Milk samples from 564 udder quarters and udder halves from 171 animals consisting of 60 dairy cows, 51 camels, and 60 goats were tested for mastitis. Sixty-four positive udder milk samples were cultured, and bacterial mastitis pathogens were isolated and identified. The antibiotic resistance of bacterial isolates from milk with mastitis was tested against nine antimicrobials commonly used in the study area. Cow- and quarter-level prevalence of mastitis in dairy cows, camels, and goats was 33.3%, 26.3%, and 25% and 17.6%, 14.5%, and 20%, respectively. In cattle, the prevalence was significantly higher in Dugda Dawa than in Bule Hora. Major bacterial isolates were coagulase-negative Staphylococcus species (39.1%), S. aureus (17.2%), S. hyicus (14.1%), and S. intermedius and Escherichia coli (9.4% each). In camels, udder abnormality and mastitis were significantly higher in late lactation than in early lactation. Mastitis tends to increase with parity in camels. E. coli isolates were highly resistant to spectinomycin, vancomycin, and doxycycline, whereas most S. aureus isolates were multidrug-resistant. Most of the rural and periurban communities in this area consume raw milk, which indicates a high risk of infection with multidrug-resistant bacteria. We recommend a community-focused training program to improve community awareness of the need to boil milk and the risk of raw milk consumption.


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