**3.3.3 Antimicrobial resistance (AMR) patterns**

A comparison of the AMR patterns of isolates with indistinguishable PFGE profiles revealed variations within the groups (Table 11). In profile 1, 2 bovine and 1 human isolates shared similar AMR and PFGE profiles. Second observation was recorded for 1 swine and 20 cattle.


*AM-Amoxacillin/Clavulonic acid, AMP-Ampicillin,CX-Ceftixiaxone, CL-Chloramphenicol, GEN-Gentamicin, KAN-Kanamycin, STR-Streptomycin, SU-Sulfizoxazole,TET-Tetacycline* 

Table 10. Relationship of molecular types and antibiotic resistance patterns of *Salmonella enterica* serotype isolated from man, domestic animals and animal products.

232 Salmonella – A Dangerous Foodborne Pathogen

II Cattle 2 (2.1) 7(7.3) - - 9(9.4)

III Cattle - 10(10.4) - - 10(10.4)

IV Cattle - 4(4.2) - - 4(4.2)

Year of isolation and number isolated (%) 2003 2004 2005 2006 Total

Cattle - 19 (19.8) 2 (2.1) 1 (1.0) 22 (22.9) Human - 4 (4.2) 12 (12.5) 1 (1.0) 17(17.7) Swine - - - 1(1.0) (1.0)

Human - 2 (2.1) 8(8.3) - 10(10.4)

Human - - 4(4.2) - 4(4.2)

Human - - 1(1.0) - 1(1.0)

meat - - 1(1.0) - 1(1.0) Human - - - 1(1.0) 1(1.0) swine - - - 1(1.0) 1(1.0)

meat - - - 1(1.0) 1(1.0) Human - - 1(1.0) - 1(1.0)

Cattle - 4(4.2) - - 4(4.2) Human - - 6(15) - 6(12.5) Chicken - - 1(1.0) - 1(1.0)

meat - - - 1(1.0) 1(1.0) Human - 1(1.0) - - 1(1.0) Total 2(2.1) 51(53.1) 36(37.5) 7(7.3) 94(100)

Xbal profiles with indistinguishable fingerprint

I

V

VI

VII

VIII

Host

Turkey

Turkey

Turkey

**3.3.3 Antimicrobial resistance (AMR) patterns** 

Table 9. PFGE profiles, host species and year of isolation of the *Salmonella* serotypes.

A comparison of the AMR patterns of isolates with indistinguishable PFGE profiles revealed variations within the groups (Table 11). In profile 1, 2 bovine and 1 human isolates shared similar AMR and PFGE profiles. Second observation was recorded for 1 swine and 20 cattle.

Antimicrobial Drug Resistance and Molecular Characterization

No of susceptibility isolates (%)

> 2 (100.0)

(93.5) - <sup>2</sup>

(91.9) - <sup>1</sup>

(2010a, 2010b) was conducted from October 2006 to March 26, 2007.

3

62 (100.0)

62


Nalidixic acid (0.5–32)

Streptomy-

Sulfizoxazole (16–512)

Tetracycline

Trimethoprimsulfamethoxazole (4-76)

**4. Discussion** 

97 (99.0)

cin (32–64) 2 (2.0) <sup>58</sup>

(4–32), - <sup>57</sup>

97 (99.0)

domestic animals and human.

**4.1** *Salmonella* **from animals 4.1.1** *Salmonella* **in feedlot cattle** 

of *Salmonella* Isolated from Domestic Animals, Humans and Meat Products 235

(93.5) - - - - - <sup>98</sup>

Table 11. Drug susceptibility patterns of the common *salmonella* serotypes isolated from

The study by Tabe et al (2010a, 2010b) reported *Salmonella* prevalence of 12.7% in fecal samples tested. A larger study (Dargatz et al 2003) that evaluated presence of *Salmonella* in fecal samples from cattle in US feedlots (73 feedlots in 12 states during the period from October 1999 to September 2000) had earlier reported a lower overall *Salmonella* prevalence of 6.3%. However, *Salmonella* prevalence at pen and feedlot level was higher. In that study (Dargatz et al 2003) although overall individual animal prevalence was 6.3% (654/10,417), 22.2% (94/422) of pens and 50.7% (37/73) of feedlots had one or more positive samples. Samples collected during the period of April to June (6.8%, 209/3054) and July to September (11.4%, 286/2500) were more likely to be positive than those collected during October to December (4.0%, 73/1838) and January to March (2.8%, 86/3025). The study by Tabe et al

An understanding of the genetic diversity of *Salmonella* isolated from cattle could help determine if contamination at a feedlot is due to bacteria that are transient or resident (Galland et al., 2001) in their gut. Transient bacteria can be introduced into the feedlot by arriving cattle, in ingredients for cattle rations such as legume hay, from contaminated water sources, or by other animals (wild or domestic), motor vehicles, and employees (Galland et al., 2001). In the study by Tabe et al (2010a, 2010b), the isolation of *S*. Typhimurium vars Copenhagen as the major *Salmonella* serovar 95% of the time supported previous reports (Hegde et al., 2005; Khaitsa et al., 2007a) of the existence of common genotypes circulating among the steers. *Salmonella* Typhimurium vars Copenhagen which was primarily reported to be found in pigeons is now frequently isolated from cattle, swine,

No. of intermediate isolates (%)

Cattle Human Swine Turkey Cattle Human Turkey Cattle Human Swine Turkey

(66.7) - - - <sup>96</sup>

(33.3) - - - <sup>98</sup>

(100) 2(100) 3(100) - - - 1(1.0) - - -

(100.0) - - - 1(1.0) - - -

No. of resistant isolates (%)

(98.0) 4(6.5) <sup>2</sup>

(100.0) 4(6.5) <sup>2</sup>

(100) 5(8.1) <sup>2</sup>

(100.0)

(100.0)

(100)

1 (33.3)

3 (100.0)

2 (66.7)

The rest shared the PFGE but not the AMR profiles. The AMR profile AM,AMP,CL, STR,SU,TET appeared the most common across many PFGE profiles, recorded in 20 bovines and 1 human (profile 1), 8 bovines (profile II), 10 bovines (profile III), 4 bovine (profile IV), 1 swine and 1 turkey (profile V) and 4 bovines (profile VII). Details of AMR profiles of other PFGE profiles will be provided. For the antibiotic susceptibility tests, a total of 9 antibiotic resistant patterns were found for the 55 animal isolates and 40 human isolates with identical PFGE profiles. Of these, cattle isolates accounted for 7, human 19, swine 2, turkey meat 3 and chicken 1 AMR patterns. A review of susceptibility levels of different isolates was summarized. All human (62), swine (2) and turkey (3) and 97 out of 98 cattle isolates were susceptible to amikacin. Resistance to amoxicillin/clavulanic acid was observed in swine (all 2 isolates) and 75 cattle isolates (76.5%) while turkey (n=2, 100%) and human (n=59, 95.2%) were mostly susceptible. All the 2 swine isolates were susceptible to cefoxitin, ceftriaxone, ciprofloxacin, gentamycin, nalidixic acid and trimethoprim/sulfamethoxazole, while resistant to amoxicillin/clavulanic acid, ampicillin, streptomycin, sulfizoxazole and tetracycline. Detailed antimicrobial susceptibility profiles of the different isolates by origin are shown in Tables 10 and 11.



Table 11. Drug susceptibility patterns of the common *salmonella* serotypes isolated from domestic animals and human.
