Biofilm Formation and Antibiotic Resistance of Coagulase-Negative Staphylococci Isolated from Lactating Women with Mastitis in Baghdad, Iraq

Mastitis is a significant problem for many lactating women. It is most common during the first 3 months postpartum. Antibiotics resistance is a trouble of deep scientific anxiety both in hospital and the public settings. Spreading of utilization of a wide spectrum antibiotics increased the rate of antimicrobial resistance among mastitis-causing agents. In addition, biofilm building is great virulence agent of the strains involved in mammary gland infections, taking into account the capacity of drug to cross through bacterial biofilm is related to each antibiotic. Therefore, this study was aimed to isolate Coagulase-Negative Staphylococci and to determine their biofilm production capacity and antibiotics susceptibility.

A total of 247 specimens (breast milk) were collected from lactating women, 147 lactating women with mastitis and 100 from healthy women. The primary identification was based on macroscopic appearance, Grams staining and biochemical tests.

A total of (74) coagulase-negative Staphylococcus isolates were detected (56 from mastitis cases and 18 from controls). Isolates demonstrated the diverse species of the CoNS isolates. Significantly higher rates of isolation of CoNS from lactating mastitis cases was during the later months of lactation than in early months for the same cases. The results of the present study showed a high incidence of mastitis (28/56; 50%) in the period of 12–24 months post-partum than other times.

Coagulase-negative staphylococcus species are an important cause of lactating mastitis and significantly more than in lactating control cases. As there is a significantly higher rate of isolation of CoNS from lactating mastitis cases during the later months of lactation than in early months, particularly in those who fed their babies normally (breast feeding) than in case of those who practiced a mixed type of feeding (breast + bottle). The resistance to diverse antibiotics and a higher ability to form biofilms, found among the strains isolated from milk of women suffering mastitis, might explain the chronic and/or recurrent nature of this infectious condition.