Avicenna Journal of Clinical Microbiology and Infection
Volume:9 Issue: 4, Dec 2022

This study aimed to investigate the epidemiology and antibiogram of clinical Staphylococcus aureus isolates from three tertiary care hospitals in Dhaka, Bangladesh.

A total of 185 clinical S. aureus isolates were studied from March 2016 to February 2017 and identified by standard microbiological methods, and an antibiogram was determined by disc diffusion method. A duplex polymerase chain reaction (PCR) assay was performed on all isolates to detect femA and mecA genes of S. aureus.

Among the 185 isolates, all (100%) were positive for the femA gene, 76 (41.1%) were methicillinresistant S. aureus (MRSA), and 109 (58.9%) were methicillin-susceptible S. aureus (MSSA). The highest and the lowest frequency of both MRSA were isolated from pus and urine specimens, respectively. All 185 S. aureus were 100% sensitive to both vancomycin and linezolid and were highly sensitive towards rifampicin (94%), meropenem (87%), gentamicin (85.4%), and cotrimoxazole (82.2%), whereas the highest resistance was against penicillin G (94.6%) followed by amoxicillin/clavulanic acid (82.7%), azithromycin (72.4%), amoxicillin (66.5%), and ciprofloxacin (63.2%). After vancomycin and linezolid, MRSA showed good susceptibility to rifampicin, cotrimoxazole, and gentamicin, while MSSA exhibited high sensitivity toward rifampicin, gentamicin, cefoxitin, meropenem, cloxacillin, ceftriaxone, and cotrimoxazole. Furthermore, MRSA was significantly more resistant to antibiotics than MSSA (P value < 0.05), and the majority of S. aureus (81.1%), MRSA (97.4%), and MSSA (69.7%) were multidrug-resistant (MDR).

Our findings can guide physicians to provide effective antibiotic therapy, implement monitoring and control strategies to reduce antimicrobial resistance, and prevent the dissemination of MRSA and MDR in the environment.

Nowadays, ceftriaxone is being used widely and its use is less compatible with the current guidelines. The aim of this study was to determine the appropriate use of ceftriaxone. The results may help to find a way to prevent its inappropriate use in the emergency department (ED).

In this observational-analytical study, the patients who were referred to EDs of two teaching hospitals from September 23, 2019, to March 19, 2020, and treated with ceftriaxone were analyzed. The appropriate use of ceftriaxone was determined based on the latest evidence-based literature.

Ceftriaxone had been prescribed properly in 156 patients (38.4%; 95% CI, 33.5-42.9%) and its use did not meet logical criteria in the remaining 250 patients (69.6%; 95% CI, 57.1-66.5%). The appropriate use of ceftriaxone was independently related to goal-directed use, level I triage, urinalysis (U/A) indicating urinary tract infection (UTI), and chest radiographic evidence of pneumonia.

Our study revealed the inappropriate use of ceftriaxone in teaching medical centers; therefore, further education seems to be necessary in this field.

Salmonella enterica serovar Typhimurium is considered one of the most important emerging food-borne pathogens in public health worldwide. Meat is commonly known as the food sources responsible for the salmonellosis outbreak.

Overall, 141 different meat samples were randomly collected from local markets. The conventional culture method was performed to isolate Salmonella spp., and then, using two pairs of primers, a multiplex polymerase chain reaction (PCR) assay was employed to confirm the identification of isolated colonies as Salmonella spp. and determine serovars as Typhimurium.

Out of 141 samples, 48 (34%) ones were presumptively isolated as Salmonella on the Salmonella agar medium and distributed as 24%, 23%, and 42% among veal, lamb, and chicken meat, respectively. However, the results of multiplex PCR showed that 4.9% of chicken meat was merely identified as S. Typhimurium. In general, S. Typhimurium isolates were found only in chicken meat.

Salmonella Typhimurium isolates were only observed in the chicken meat. Multiplex PCR was found to be a specific and rapid alternative method for the identification of various types of Salmonella.

Salmonella Typhimurium and Listeria monocytogenes are among the most important foodborne pathogens, and new methods to remove them from surfaces are useful. The aim of this study was to investigate the bactericidal effect of a combination of sodium dodecyl sulfate (SDS) and some food matrix-related factors such as temperature, salinity, acidity, and exposure time on L. monocytogenes and S. Typhimurium in suspension and on different food industry related surfaces.

The bacterial strains were treated with different concentrations of SDS, citric acid, lactic acid, and NaCl at different temperatures at various times. At least one concentration was selected that caused one or less log reduction in the viability of each bacterium, and the combination treatments were examined in this regard. The best combination was then selected, and its bactericidal effect on the bacteria tested was evaluated on ceramic, stainless steel, and plastic surfaces.

The results showed that the sensitivity of the bacteria studied to different disinfectants was different. L. monocytogenes was highly sensitive to SDS, while S. Typhimurium was relatively resistant to SDS. Both bacteria were more sensitive to lactic acid than to citric acid, and the bactericidal effects of the disinfectants were enhanced in the combined treatments at 45ºC compared to 35ºC treatments. The addition of NaCl to the SDS solution resulted in a strong reduction in the bactericidal effect of SDS. The selected disinfectant removed bacterial biofilms from stainless steel surfaces in a shorter time than ceramic and plastic surfaces.

The preparation of combined solutions using SDS and an organic acid at an appropriate concentration and temperature could be useful for removing or reducing bacterial biofilms. Therefore, the combination of SDS and the lactic acid at 45°C can effectively remove pathogenic bacteria from various surfaces.

Staphylococcus aureus, as a major food-borne pathogen, is the most commonly isolated bacterium from bovine mastitis. However, some S. aureus strains exhibit a high rate of antibiotic resistance, among which, methicillin-resistant S. aureus (MRSA) is very important. The present study was conducted to isolate, characterize, and determine the antibiotic resistance profile of MRSA strains in milk.

Staphylococcus aureus strains were isolated and identified from 415 milk samples collected from apparently healthy cattle in Hamedan province, Iran. Molecular characteristics of the strains were identified using multiplex polymerase chain reaction (PCR) and the antibiotic resistance profile of the isolates was determined by Kirby-Bauer disk diffusion susceptibility test.

A total of 76 S. aureus strains were isolated and identified. The PCR results indicated that 50 (65.78%) isolates possessed mecA gene and were found to be MRSA strains. Twelve isolates (15.78%) showed phenotypic resistance to oxacillin in disk diffusion method. All 76 S. aureus isolates (100%) were resistant to penicillin and susceptible to ciprofloxacin and gentamicin.

The results of the present study indicated that bovine milk may contain MRSA strains and this is worrying as these isolates may transfer multi-drug resistance to the isolates that circulate among humans, animals, and food chains.

Nowadays, antimicrobial resistance is one of the most important concerns caused by the extensive use of antibiotics. Efforts to find new materials with antimicrobial effects have been continued more seriously than before. Nanoparticles (NPs) with very small dimensions and extraordinary properties have the potential to overcome antimicrobial resistance, so the use of previous antimicrobial substances at the nanometer dimensions to investigate physicochemical and antimicrobial effects could help overcome these universal concerns.

In this study, NPs were synthesized by hydrothermal-assisted microwave technique. Scanning electron microscopy (SEM), dynamic light scattering (DLS), and atomic force microscopy (AFM) were carried out to investigate the physicochemical properties. Further, energy dispersive spectroscopy and Fourier-transform infrared spectroscopy analyses were carried out to analyze the chemical composition of nanocomposites. Then, their minimum inhibitory concentration was measured on seven bacterial isolates.

The majority of NPs were in the range of 40-100 nanometers which is the well-optimized size for our purpose. Antimicrobial analysis revealed the effect of synthesized nanocomposites on every seven microbial isolates, including three gram-positive isolates (i.e., Staphylococcus aureus, Micrococcus luteus, Bacillus subtilis) and four gram-negative isolates (i.e., Serratia marcescens, Escherichia coli, Pseudomonas aeruginosa, Klebsiella pneumoniae).

Synthesized nanocomposite revealed a good antimicrobial effect on all bacterial isolates. It is suggested to investigate the cellular toxicity of synthesized nanocomposite in the next studies.

Ectoparasites in domestic animals (sheep and goats) play important roles in transmitting the widest range of pathogens and can induce considerable economic losses in the animal husbandry industry. This study was undertaken to evaluate the prevalence and species’ variation of ectoparasites in the sheep and goats and its risk factors in Sanandaj, Kurdistan province, western Iran.

The ectoparasites of 4576 animals; that is, 1954 sheep (416 + 1538) and 2622 goats (1084 + 1538) were collected in the abattoir and different rural regions (N = 32) of Sanandaj. Determination of ectoparasites was done using a stereomicroscope according to the identification keys.

Results indicated that 925 sheep (47.33%) and 811 goats (30.93%) were infested with ectoparasites. There was a significant difference between the prevalence and sex in sheep aged less than one-year old (P ≤ 0.05). Moreover, the highest and lowest prevalence of ixodid tick infestations was observed for Boophilus spp. (35.36%) and Rhipicephalus spp. (3.06%), respectively. In addition, the highest body infestation to be detected was on the ears (24.82%) of Rhipicephalus (P ≤ 0.05) with 2.13 ticks in each animal. The frequency of tick infestation was remarkably higher in spring (33.82%) than in other seasons. Furthermore, 143/416 (34.37%) and 109/416 (26.2%) sheep as well as 113/1084 (10.42%) and 87/1084(0.86%) goats were infested with Ctenocephalides canis and Pulex irritans, respectively. Myiasis resulting from Przhevalskiana fly larvae was merely observed in the goat population at the abattoir. Haematopinus spp, Linognathus spp., and Damalinia were detected, and the prevalence of lice infestation was significantly higher in the goats 831/1538 (54.03%) rather than in the sheep 20/1538 (1.3%).

This is the first report on ectoparasites fauna in the sheep and goats in Sanandaj, western Iran. Furthermore, it was confirmed that various ticks can not only transmit pathogens to humans but also induce tick-borne disease in animals in the region.