Transmission of Antibiotic-Resistant Escherichia coli from Chicken Litter to Agricultural Soil

A growing concern regarding the use of animal manure as fertilizer is the contamination of soil, plants, and the environment with a variety of antibiotic-resistant and pathogenic bacteria. This study quantified and characterized the antibiotic resistance profiles of Escherichia coli in soil before and after chicken litter application to determine the impact of manure on the soil resistome. Litter and soil samples were collected from a sugarcane field before and after litter application. E. coli was isolated and quantified using the Colilert®-18/Quanti-tray® 2000 and 10 randomly selected isolates from the positive wells of each Quanti-tray were putatively identified on eosin methylene blue agar. Real-time PCR was used to confirm the isolates by targeting the uidA gene. Antibiotic susceptibility test against 18 antibiotics was conducted using the disk diffusion method, and the multiple antibiotic resistance index was calculated. Soil amendment with chicken litter significantly increased the number of antibiotic-resistant E. coli in the soil. Among the 126 E. coli isolates purified from all the samples, 76% showed resistance to at least one antibiotic, of which 54.2% were multidrug-resistant (MDR). The highest percentage resistance was to tetracycline (78.1%), with the least percentage resistance (3.1%) to imipenem, tigecycline, and gentamicin. The isolates also showed resistance to chloramphenicol (63.5%), ampicillin (58.3%), trimethoprim-sulfamethoxazole (39.6%), cefotaxime (30.2%), ceftriaxone (26.0%), cephalexin (20.8%), cefepime (11.5%), amoxicillin-clavulanic acid (11.5%), cefoxitin (10.4%), Nalidixic acid (9.4%), amikacin (6.3%), and ciprofloxacin (4.2%). Of the 54.2% (52/96) MDR, the highest number was isolated from the litter-amended soil (61.5%) and the least isolates from soil samples collected before litter application (1.9%). The relatively higher mean MAR index of the litter-amended soil (0.14), compared to the soil before the amendment (0.04), suggests soil pollution with antibiotic-resistant E. coli from sources of high antibiotic use. E. coli could only be detected in the soil up to 42 days following manure application, making it a suitable short-term indicator of antibiotic resistance contamination. Notwithstanding its relatively short detectability/survival, the application of chicken litter appeared to transfer antibiotic-resistant E. coli to the soil, enhancing the soil resistome and highlighting the consequences of such agricultural practices on public health.

Mitigating Potassium Leaching from Muriate of Potash in a Tropical Peat Soil Using Clinoptilolite Zeolite, Forest Litter Compost, and Chicken Litter Biochar

Using muriate of potash (MOP) as a source of potassium (K) is a cost-effective method for crop production in tropical peat soils. However, exchangeable K commonly leaches from tropical peat soils because of high rainfall and a lack of clay to retain this cation. Potassium retention as exchangeable K could inhibit K loss through leaching to increase K availability. Clinoptilolite zeolite (CZ), forest litter compost (FLC), and chicken litter biochar (CLB) can be used to retain K from MOP in tropical peat soils for crop use because of the high affinity of CZ, FLC, and CLB for K ions. These approaches can be used as innovative and sustainable alternatives for the frequently used lime (CaCO3). However, information on using CZ, FLC, and CLB for MOP K retention is limited. Thus, CZ, FLC, and CLB were tested in a leaching study to determine their effects on MOP K retention in tropical peat soil. The use of CZ and FLC at rates of 100% and 75% of the recommended rate for pineapple cultivation (a commonly grown fruit crop in tropical peat soils in Malaysia) improved the K availability, pH, and CEC of the peat soil because of the high CEC of CZ and the humic substances (humic acids, fulvic acids, and humin) of FLC, which have a high affinity for K ions. The CLB did not improve K retention because of the competition between K, Ca, Mg, and Na ions, which are inherently high in this soil amendment. Instead of liming, which only replaces a few of the leached cations, such as calcium, the results of this study suggest an alternative method of retaining peat cations, such as K, that reduce peat acidity. This alternative method of retaining peat soil cations, especially K ions, is a practical and sustainable approach for improving peat soil productivity.

Detection and Antimicrobial Resistance of Staphylococcus spp from Chicken, Litter and Humans in Addis Ababa, Ethiopia

Background: In veterinary medicine, three Staphylococcus species are of particular importance as a primary cause of specific diseases; S. aureus (mastitis in ruminants, equine botryomycosis and bumble foot in poultry), S. hycus (porcine exudative epidermitis) and S. intermedius (canine pyoderma). The disease conditions caused by Staphylococcus in poultry vary with the site, the route and predisposing factors include wounds as a result of fighting/cannibalism, immunosuppression based on virus infections or parasite infestations, and bad husbandry conditions (overcrowding). Besides their role as colonizer or pathogen in different hosts, Staphylococcus, which colonizes food-producing animals, can contaminate carcasses during slaughter and play a role as contaminant in the subsequent manufacturing process in food of animal origin, such as pork, beef, veal, milk, poultry meat or poultry meat products Methods: A cross-sectional study was conducted on apparently healthy chicken, farm personnel and litter at chicken farms in Addis Ababa, Ethiopia from March 2015 to May 2015. The objectives of this study were to isolate and identify Staphylococcus spp from chicken, litter and personnel at chicken farm; and to determine the antimicrobial susceptibility profile of the isolates. A total of 222 samples consisting of 101 cloacal swabs, 90 tracheal swabs, 17 pooled litter swabs, 7 nasal swabs and 7 pooled hands and boot swabs were collected from six farms and examined for the presence of Staphylococcus species and antimicrobial resistance against 10 antimicrobial agents following recommended standard procedures. Results: The result showed that the overall proportion of Staphylococcus was 64/222 (28.83%). Of the isolates 40/64 (62.5%), 11/64 (17.2%), 3/64 (4.7%) and 10/64 (15.6%), were S. aureus, S. hycus, S. intermedius and CNS, respectively. Only one isolate of S. aureus was susceptible to all antimicrobials tested Of the 10 antibiotics tested, Penicillin G showed the highest (96.9%) resistance followed by Tetracycline (78.1%), Amoxicillin and Erythromycin at the same level (65.6%). Conversely, Ciprofloxacin showed the highest susceptibility (95.3%) followed by Sulphamethoxazole-trimethoprim (85.9%). Out of 64 isolates, 61/64 (95.3%) were resistant to three or more antimicrobials tested. Of the isolates, 38/40 (95%) S. aureus, 10/11 (90.9%) S. hycus, 3/3 (100%) S. intermedius and 10/10(100%) CNS showed multi drug resistance (to three or more antimicrobials). Conclusion: This study showed considerable proportion of Staphylococcus spp in chicken, litter and farm workers with a potential source of resistant Staphylococcus species more importantly multi drug resistance strains. Further study on molecular characterization of the isolates will be essential to identify the resistant genes and establish epidemiological link in the transmission dynamics of resistant Staphylococcus species between poultry and humans.

Dielectric response of nitrogen in soil amended with chicken litter biochar and urea under Oryza sativa L. cultivation

Unbalanced utilization of nitrogen (N) rice not economically viable neither is this practice environmental friendly. Co-application of biochar and urea could reduce the unbalanced use of this N fertilizer in rice cultivation. Thus, a field study was carried out to: (i) determine the effects of chicken litter biochar and urea fertilization on N concentration in soil solution of a cultivated rice (MR219) using dielectric measurement at a low frequency and (ii) correlate soil dielectric conductivity with rice grain yield at maturity. Dielectric response of the soil samples at 20, 40, 55, and 75 days after transplanting were determined using an inductance–capacitance–resistance meter HIOKI 3522-50 LCR HiTESTER. Selected soil chemical properties and yield were determined using standard procedures. The dielectric conductivity and permittivity of the soil samples measured before transplanting the rice seedlings were higher than those for the soil samples after transplanting. This was due to the inherent nitrogen of the chicken litter biochar and the low nitrogen uptake at the transplanting stage. The soil N response increased with increasing measurement frequency and N concentration. The permittivity of the soil samples was inversely proportional to frequency but directly proportional to N concentration in the soil solution. The estimated contents of N in the soil using the dielectric conductivity approach at 1000 Hz decreased with increasing days of fertilization and the results were similar to those of soil NH4+ determined using chemical analysis. The conductivity measured within 1000 Hz and 100,000 Hz correlated positively with the rice grain yield suggesting that nitrogen concentration of the soil can be used to estimate grain yield of the cultivated rice plants.

Utilization of urea and chicken litter biochar to improve rice production

The use of N fertilizers on tropical acid soils is increasing because of their low native fertility. Chicken litter biochar was used to improve N use efficiency and rice yield. The objective of this study was to determine the effects of chicken litter biochar on selected chemical properties of a tropical acid soil under rice (MR219) cultivation. Treatments evaluated were in this study were as follows: (1) T1, soil only, (2) T2, existing recommended fertilization, (3) T3, chicken litter biochar alone, and (4) T4, chicken litter biochar + existing recommended fertilization. Plant and soil analyses were conducted using standard procedures. The use of chicken litter biochar increased soil pH, total carbon, total P, available P, total N, and exchangeable N. Also, this practice decreased soil total acidity and exchangeable Al3+. Compared with T2, T4 significantly increased Crop Recovery Efficiency and Agronomic Recovery Efficiency of N. This resulted in a significant increase in the grain yield (11 t ha−1) of MR219 (Malaysia hybrid rice) for T4 compared with the existing rice grain yield of 5.9 t ha−1 (T2). Moreover, application of chicken litter biochar (5 t ha−1) to tropical acid soil suggested that N application can be reduced to 26.67%, 30.03%, 30.15%, and 14.15% of the recommended rates by MADA on days 10, 30, 50, and 70 after transplanting, respectively. Chicken litter biochar can improve the chemical properties of tropical acid soils and rice (MR219) grain yield.