Salmonella isolates serotypes and susceptibility to commonly used drugs at a tertiary care hospital in Riyadh, Saudi Arabia.
BACKGROUND
Resistance of Salmonella to therapeutic agents currently being used for treatment of Salmonella infections is emerging as a global problem. This study aimed to assess the prevalence of Salmonella serotypes and their susceptibility patterns to commonly used drugs for treatment of Salmonella infections including quinolones. Correlation between nalidixic acid susceptibility of these isolates and their ciprofloxacin minimum inhibitory concentrations was also sought.


METHODS
Salmonella isolates (n=213) were collected between January 2007 and May 2009 at King Khalid University Hospital in Riyadh, Saudi Arabia. The isolates were serotyped and their susceptibilities to commonly used first-line anti-Salmonella drugs (ampicillin, ceftriaxone, trimethoprim/sulfamethoxazole, nalidixic acid and ciprofloxacin) were determined using the automated Microscan system, the Kirby-Bauer disk diffusion method, and E-test.


RESULTS
The most frequently detected serotype was D1 (37%) followed by the serotypes, B (24%) and C1 (11%). Non-typable Salmonella isolates detected using available conventional Salmonella anti-sera were (11%). Overall resistance rates to nalidixic acid, ampicillin, trimethoprim/sulfamethoxazole and ceftriaxone were 99/213 (46%), 43/213 (20%), 34/213 (16%) and 7/213 (3%), respectively. Of the total isolates, 117 (55%) had a ciprofloxacin MIC of <0.125 µg/ml and among these 105 (90%) were susceptible to nalidixic acid. The remaining 96 (45%) isolates had a ciprofloxacin MIC of ≥ 0.125 µg/ml and among them, 83 (86.5%) were resistant to nalidixic acid.


CONCLUSIONS
The majority of Salmonella isolates in this study were non-typhi serotypes. Significantly higher proportions of Salmonellae were resistant to nalidixic acid and ciprofloxacin and a vast majority of nalidixic acid resistant organisms exhibited decreased susceptibility to ciprofloxacin.
Department of Pathology, College of Medicine, King Saud University and King Khalid University Hospital, Riyadh Saudi Arabia. ali.somily@gmail.com
Ali Mohammed
AM
Somily
Samina Bashir
SB
Sayyed
Hanan Ahmed
HA
Habib
Abdulaziz Saleh
AS
Al-Khattaf
Fawzia Eida
FE
Al Otabi
Zahid
Z
Shakoor
Abdelmageed Mohammed
AM
Kambal
D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D002648:Child; D002675:Child, Preschool; D024881:Drug Resistance, Bacterial; D005260:Female; D006761:Hospitals; D006801:Humans; D007223:Infant; D008297:Male; D008826:Microbial Sensitivity Tests; D008875:Middle Aged; D015995:Prevalence; D011446:Prospective Studies; D012475:Salmonella / Q000145:classification* / Q000187:drug effects* / Q000302:isolation & purification; D012480:Salmonella Infections / Q000453:epidemiology* / Q000382:microbiology*; D012529:Saudi Arabia / Q000453:epidemiology; D012703:Serotyping; D055815:Young Adult
D000900:Anti-Bacterial Agents