Nosocomial Spread of a Staphylococcus hominis subsp. novobiosepticus Strain Causing Sepsis in a Neonatal Intensive Care Unit

Abstract

From 2002 to 2003, 32 isolates of Staphylococcus hominis subsp. novobiosepticus (SHN) were recovered from 21 patients, 18 of whom were neonates, with 13 considered to have late-onset SHN sepsis. All isolates from neonates had an indistinguishable pulsed-field gel electrophoresis pattern. Our data support SHN as an important nosocomial pathogen in neonates.Coagulase-negative staphylococci (CoNS) are now recognized as a major cause of nosocomial infections in neonatal intensive care units (NICUs) (8) and are responsible for 48% of late-onset sepsis among very-low-birth-weight neonates (20). Although Staphylococcus epidermidis causes 60 to 93% of CoNS bloodstream infections, several other CoNS species are reported to cause disease in infants (10,11,18). Recently, a novel subspecies of Staphylococcus hominis, S. hominis subsp. novobiosepticus (SHN), was isolated from blood cultures and other clinical specimens (6, 12). The name derives from the combination of novobio, pertaining to the property of novobiocin resistance, and septicus, pertaining to the ability to cause sepsis. After isolating SHN from several blood cultures at the NICU during 2002 and 2003, we undertook a retrospective study in our 1,300-bed tertiary care institution to determine the prevalence of this subspecies, the clinical significance of the isolates, and whether the infections were clonal in origin.Clinical records of patients from whom SHN had been isolated were reviewed. Diagnosis of sepsis was based on the assessment of the attending physician. For NICU patients, true infection was defined either by isolation of SHN from two separate blood cultures or by a single SHN-positive blood culture and an elevated serum level of C-reactive protein (Ն2 mg/dl). Blood samples were inoculated and processed in an automated system (BacT/Alert [BioMérieux, Durham, NC] or BACTEC 9240 [BD Diagnostics, Sparks, MD]). The type strain of SHN (ATCC 700236) was used as a reference standard throughout the investigations. Identification and susceptibility testing were performed using conventional methods and the Wider system (Soria Melguizo, Madrid, Spain) (3, 16). A zone of inhibition measuring Յ15 mm in Mueller-Hinton agar or Յ11 mm on Trypticase soy agar plates was considered indicative of novobiocin resistance (12). All isolates of SHN underwent confirmatory PCR analysis for the mecA gene (7). To confirm the identification of SHN, broad-spectrum primers were used for sequencing the 5Ј ends of both strands of the 16S rRNA gene (2, 6) using an ABI Prism 3100 genetic analyzer (Applied Biosystems, Foster City, CA). Further molecular characterization of SHN isolates was performed by pulsed-field gel electrophoresis (PFGE) following digestion of DNA extracts with SmaI (5).During 2002 and 2003, 32 isolates of SHN were recovered from 21 patients. Twenty-three isolates were from blood cultures, six were from catheters, one was from cerebrospinal fluid (CSF), one was from a wound, and one was from external ear fluid. All 21 patients yielded an SHN-positive blood culture. A...

Public computer surfaces are reservoirs for methicillin-resistant staphylococci

“…BLAST analysis of these sequences revealed 100% similarity to S. hominis and S. epidermidis (Table 1) (GenBank accession numbers DQ831715-DQ831721). These results support the conclusion that the oxacillin-resistant bacterial community contaminating individual keyboards was not limited to MRSA and/or MRSE but was complex and included, for example, S. hominis (MRSH), a known nosocomial pathogen (Chaves et al, 2005).…”

Antibiotics Sensitivity Profile Towards <i>Staphylococcus hominis</i> in Assir Region of Saudi Arabia

“…All 21 isolates were resistant to nalidixic acid and susceptible to vancomycin. PCR analysis confirmed that all strains possessed a mecA gene homologue [9]. These findings are almost similar to the antibiotic sensitivity pattern in our study, as drugs found to be resistant to all patients were: Penicillin, erythromycin, ampicillin.…”

Multilocus Sequence Typing and Further Genetic Characterization of the Enigmatic Pathogen, Staphylococcus hominis

“…Sixty-eight isolates were from three hospitals in the USA (Illinois, n = 26; Mississippi, n = 1; New York, n = 41), 17 isolates were from one hospital in Spain, including 15 isolates from an outbreak among neonates and two isolates from adults that were not associated with the outbreak [17], five isolates were from a hospital outbreak among adults in Brazil [18], and 16 isolates were selected to be diverse by geography (Argentina, n = 1; Colombia, n = 1; Italy, n = 1; Japan, n = 1; Portugal, n = 2; Mexico, n = 3; Tunisia, n = 7) and by their different Xho I pulsed-field gel electrophoresis (PFGE) patterns that were characterized according to Bouchami et al [30]. In addition, American Type Culture Collection (ATCC) strains ATCC 27844 T and ATCC 700236 T were included as the S. hominis subsp.…”