Isolation, Identification and Antimicrobial Susceptibility Pattern of Tatumella ptyseos Strains Isolated From Powdered Infant Formula Milk Consumed in Neonatal Intensive Care Unit: First Report From Iran

Tatumella ptyseos is a rod-shaped, Gram-negative, facultative, and anaerobic bacteria categorized in the Enterobacteriaceae family. It is a rare food-borne opportunistic pathogen which causes neonatal sepsis, bacteremia, and urinary tract infections. T. ptyseos has been also cultured from various food sources around the world. It is difficult to determine the source of the infection in the patients (especially newborns) due to low information about the epidemiology of T. ptyseos. The current study aimed to investigate the isolation, identification and antimicrobial susceptibility pattern of T. ptyseos strains from the consumed powdered infant formula milk (PIF) in hospital neonatal intensive care unit (NICU). A total of 125 powdered infant formula milk (PIF) samples were purchased from drug stores from June 2011 to March 2012. T. ptyseos was isolated according to food and drug administration (FDA) method. For final confirmation, biochemical testes embedded in API-20E system were used. Drug susceptibility test was performed using the disc diffusion method, according to clinical and laboratory standard institute (CLSI) recommendations. Results of the study showed that, out of 125 samples, T. ptyseos was isolated from four (3/2%) PIF samples. All isolated strains (100%) were resistant to ampicillin, carbenicillin, cotrimoxazole and amoxicillin. The present study was the first report on the isolation and identification of T. ptyseos from PIF in Iran. T. ptyseos are frequently present in various kinds of foods; therefore, further investigation on these samples is required. It is necessary to track the T. ptyseos in a wide variety of foods and individuals especially in immunocompromised people such as human immunodeficiency virus (HIV)-positive patients to reveal the possible routes of transmission of this pathogen to humans. In addition, molecular studies are required to determine the genetic relationship between T. ptyseos strains isolated from different sources