Coagulase-negative staphylococcus

The most common cause of uncomplicated UTIs is E. coli, accounting for more than 85% of community-acquired infections, followed by Staphylococcus saprophyticus (coagulase-negative staphylococcus), accounting for 5% to 15%. 

Soge OO, Meschke JS, No DB et al (2009) Characterization of methicillin-resistant Staphylococcus aureus and methicillin-resistant coagulase-negative Staphylococcus spp. isolated from US West Coast public marine beaches. J Antimicrob Chemother 64(6) 1148-1155... 

In a rat model of neonatal sepsis, recombinant HL or talactoferrin was shown to improve survival (Venkatesh et al., 2007). In ex vivo studies, HL increased synergy of commonly used antibiotics against coagulase-negative staphylococcus and Candida (Venkatesh and Rong, 2008) and reduced biofilm of infected catheters (Venkatesh et al., 2009). 

The use of Mini-tip Culturette (Becton Dickinson, Cockeysville, MD) has been compared with traditional culture techniques using a rabbit model as well as commimity-acquired presumed bacterial keratitis. The sensitivity of the Mini-tip Culturette was 83-3% and the specificity 100%. Detected organisms included group A P-hemolytic Streptococcus, S. aureus, coagulase-negative Staphylococcus, Serratia marcescens, and Pseudomonas aeruginosa. 

A 35-year-old man was given vancomycin (1.5 g bd) for a wound infection with a coagulase-negative staphylococcus, a peptostreptococcus, and a corjmeform Grampositive bacillus. On day 37 hi white blood cell count was 2.8 x 10 /1 (baseline 5.2) with a low neutrophil count (0.5 x 10 /1). Vancomycin was withdrawn and 2 days later he was given teicoplanin 400 mg/day, by which time the cell count had increased to 3.5 x 10 /1, neutrophils 0.9 x 10 /1. On day 45, the total white cell count was 4.9 x 10 /1, neutrophils 2.3 x 10 /1. Teicoplanin was continued for 1 month, and the white cell count remained normal. 

Coagulase-negative Staphylococcus species, particularly S. epidermidis, are the most common causes of catheter-related bacteremia [25], Heavy colonization of the skin-insertion site has been shown to be strongly correlated with catheter-related bacteremia. In hemodialysis patients, the risk of S. aureus bacteremia is six times greater than in nonhemodialysis patients. And numerous incidents of intravascular infection have been traced to microbially contaminated topical disinfectants. 

Penicillin, discovered in 1929 by Fleming, was first used therapeutically in 1941. The penicillin family of antibiotics, known as p-lactams, have been used extensively and successfully to treat bacterial infections, including Staphylococcus spp. The first reported bacterial resistance to p-lactams occurred in the 1940s, when extracts of bacteria were shown to neutralize the antimicrobial properties of penicillin. Soon after, strains of S. aureus were reported resistant to penicillin, in that they produced an enzyme capable of neutralizing penicillin called penicillinase (now termed P-lactamase). Currently, this form of resistance is common in as many as 93% of all S. aureus clinical isolates. Many coagulase-negative Staphylococcus spp. (CoNS) also produce P-lactamase and so are resistant to the penicillins as well [10]. 

O Hare MD, Reynolds PE. Novel membrane proteins present in teicoplanin-rcsistam, vancomycin sensitive, coagulase negative Staphylococcus sp. ] Antimicrob Chemother 1992 30 752-768. 

Infection risk The incidence rate for infection and its associated risk factors in 271 hospitalised patients on PN followed over a 6-month period. The rate of catheter-related infection (CRI) was 25/lOOOdays of TPN, with coagulase-negative Staphylococcus the most commonly isolated microorganism. Overall mortality rate was 16.9%, and this was xmrelated to the presence or absence of CRI, or use of omega-3 lipids or olive oil in the TPN [123 ]. In a report of CRI in children on PN in a hospital centre over a 21-year period, the incidence of sepsis was significantly less with patients who continued home PN after hospital discharge compared with hospital parenteral (0.94/1000 vs 2.75/lOOOdays of PN P<0.001) [12i< ]. 

---