Methicillin‐resistant Staphylococcus aureus bacteraemia and epidural abscess in a neonate

A 24‐day‐old boy presented with fever, irritability and poor feeding. Blood culture grew methicillin‐resistant Staphylococcus aureus. Cerebrospinal fluid analysis showed pleocytosis, and methicillin‐resistant Staphylococcus aureus grew from enrichment broth. Magnetic resonance imaging revealed an epidural abscess extending from C2–3 to T8–9. Staphylococcal infections of the central nervous system are uncommon in neonates. This case demonstrates the importance of performing a lumbar puncture in isolated staphylococcal bacteraemia. The case also highlights that cerebrospinal fluid pleocytosis may indicate a parameningeal focus of infection.     

Gangrenous ecthyma of the diaper area in infants]

Ecthyma gangrenosum due to Pseudomonas aeruginosa is a skin infection in which necrotic ulcerations surrounded by a red areola develop. The diaper area is the region most often involved in infants. Typically, ecthyma gangrenosum occurs in patients with septicemia and risk factors (chemotherapy, neutropenia). However, transient bacteremia or an infection confined to the skin may be the cause in some patients, with maceration in the diaper area and previous antibiotic therapy as risk factors.     

Spread of methicillin‐resistant Staphylococcus aureus USA300 in a neonatal intensive care unit

Background: Reports of community‐associated methicillin‐resistant Staphylococcus aureus (CA‐MRSA) in neonatal intensive care units (NICU) and in otherwise healthy patients without obvious risk factors have been increasing in frequency. Described herein is a cluster of cases of CA‐MRSA USA300 strains in an NICU affecting infants, health‐care workers and the health‐care workers’ families. Methods: Infants and health‐care workers with infection and colonization due to MRSA between 1 January 2004 and 30 June 2005 in a tertiary care center NICU in San Antonio, TX were studied. Antimicrobial susceptibility testing and polymerase chain reaction detection of the mecA gene characterized the MRSA isolates. All MRSA cases were reviewed for clinical severity of infection and outcome. Results: During the 18 months studied, a total of four (0.6%) of 676 infants had CA‐MRSA bacteremia or colonization. One infant with necrotizing pneumonia died and three health‐care workers who directly cared for the infected infants developed soft‐tissue infections caused by CA‐MRSA. Four family members of two health‐care workers subsequently developed soft‐tissue infections. All of the analyzed isolates (eight of nine) belonged to pulsed‐field type USA300 and possessed Panton–Valentine leukocidin genes, which have been associated with severe skin and soft‐tissue infections, and necrotizing pneumonia. Conclusions: It is likely that the CA‐MRSA USA300 strain can be transmitted between NICU patients to health‐care workers and their family members. The CA‐MRSA cases reported here reinforce the virulence of CA‐MRSA USA300 strains and emphasize the need to embrace infection control practices designed to protect hospitalized patients, health‐care workers and their family members.     

Nosocomial transmission of community‐acquired methicillin‐resistant Staphylococcus aureus in a well‐infant nursery of a teaching hospital

Background: Infection due to community‐acquired strains of methicillin‐resistant Staphylococcus aureus (CA‐MRSA) has been reported with increasing frequency. Herein is described the nosocomial transmission of CA‐MRSA involving 13 neonates and two mothers in a well‐infant nursery in a teaching hospital in Saudi Arabia. Methods: From October to November 2009, temporally related cases of CA‐MRSA skin and soft‐tissue infection occurred in newborns shortly after discharge from a well‐infant nursery. An outbreak investigation including case identification, review of medical records, staff screening, environmental cultures, pulsed‐field gel electrophoresis, and a case–control study were conducted. Controls were selected from among asymptomatic neonates admitted to the same nursery and matched for the day of admission. Results: Fifteen subjects were found to be CA‐MRSA positive: 13 neonates and two mothers. The crude attack rate among neonates was 5.5% during the outbreak period. All 13 neonates presented with skin and soft‐tissue infection; one of the mothers had mastitis and a breast abscess. The source of the outbreak was not evident. Pulsed‐field gel electrophoresis showed that all of the tested isolates from one strain except one, all contained the staphylococcal cassette chromosome mec (SCCmec) type IV. Conclusion: MRSA strains that initially emerged in the community are now causing disease in health‐care settings. Adherence to standard infection control practices, including consistent hand hygiene, in newborn nurseries is important to prevent transmission in such settings.     

Recurrence of pelvic abscess from Panton–Valentine leukocidin‐positive community‐acquired ST30 methicillin‐resistant Staphylococcus aureus

A 17‐year‐old female patient (a basketball player) suffered from recurrent pelvic abscesses from methicillin‐resistant Staphylococcus aureus (MRSA). The first episode, from strain NN12, occurred in October 2004. Her cutaneous abscesses complicated into systemic progression to osteomyelitis and multifocal pelvic abscesses, adjacent to the sacroiliac joint. The second episode, abscesses at tissues adjacent to the sacroiliac joint from strain NN31A, occurred late in February 2005. The third episode, from strain NN31B, occurred on July 30, 2005, repeating the second episode. Three MRSA strains were identical in terms of genotypes (belonging to Panton‐Valentine leukocidin [PVL]‐positive ST30 community‐acquired MRSA, CA‐MRSA), pulsed‐field gel electrophoresis patterns, and peptide cytolysin gene (psmα) expression levels. The three MRSA strains exhibited superior THP‐1 cell invasion ability over hospital‐acquired MRSA (New York/Japan clone). The data suggest that PVL‐positive ST30 CA‐MRSA, with high levels of cell invasion and peptide cytolysins, causes recurrence of pelvic abscesses in a healthy adolescent.     

Mortality and neurodevelopmental outcome after Staphylococcus aureus bacteremia in infants

We compared outcomes in infants with methicillin-resistant and methicillin-sensitive Staphylococcus aureus bacteremia. Infants with methicillin-resistant S. aureus infection had a longer median duration of bacteremia (4.5 versus 1 day, P = 0.01), but no difference in length of hospital stay, mortality, or neurodevelopmental impairment.     

Staphylococcal scalded skin syndrome in an extremely low‐birth‐weight neonate: Molecular characterization and rapid detection by multiplex and real‐time PCR of methicillin‐resistant Staphylococcus aureus

Background: Staphylococcal scalded skin syndrome (SSSS), caused by methicillin‐resistant Staphylococcus aureus (MRSA) producing exfoliative toxin (ET), is a life‐threatening infection for neonates in neonatal intensive care units (NICUs). SSSS in extremely low‐birth‐weight (ELBW) neonates is rare. A new class of MRSA (community‐acquired MRSA, CA‐MRSA) has been emerging in the community. The aim of this study was to characterize MRSA from an ELBW neonate with SSSS, and to develop rapid detection methods for SSSS‐associated and emerging pediatric MRSA. Methods: An ELBW infant in the NICU developed SSSS on day 16 after birth. Isolated MRSA was genetically characterized and compared with CA‐MRSA from bullous impetigo (biCA‐MRSA), which is positive for the ET and collagen‐adhesin (CNA) genes in many cases, and the Panton‐Valentine leucocidin (PVL) gene rarely. Specific primers and probes for five virulence genes (for ETA, ETB, ETD, PVL, CNA) were designed for multiplex polymerase chain reaction (PCR) and real‐time PCR. Results: MRSA strain H5 from SSSS exhibited the genotype (ST91, spa416[t375], agr3, SCCmecIVa, CoaI), and possessed the ETB and CNA genes, similar to ST91 biCA‐MRSA (albeit with a divergence). Multiplex PCR detected the ETB and CNA genes of strain H5, and real‐time PCR detected strain H5 at as low as 10² CFU/mL. The assays were 100% specific and 100% sensitive, for the five virulence genes. Conclusion: ETB‐positive ST91 MRSA, which was very similar to ST91 biCA‐MRSA, was isolated from an ELBW infant with SSSS. The multiplex and real‐time PCR assays specifically or quantitatively detected SSSS‐associated and emerging pediatric MRSA.     

Detection of meticillin‐resistant staphylococcus aureus (MRSA) colonization in newborn infants using real‐time polymerase chain reaction (PCR)

Objective: Meticillin‐resistant staphylococcus aureus (MRSA) colonization on neonatal units is a common and important clinical problem. Effectiveness of polymerase chain reaction (PCR) for detecting MRSA nasal colonization of infants was evaluated and compared to culture‐based methods. The effect of skin decolonization in affected infants was studied. Methods: Paired nasal swabs were collected from infants in our neonatal unit over a 12‐month period (September 2007–2008). Colonization with MRSA was determined with a commercially available PCR method and compared to culture. Results: A total of 696 paired nasal swabs were taken. Three infants were colonized at the beginning and were included. There were positive PCRs in 12 infants. Five infants cultured MRSA from a nasal swab at the same time. No infants were culture‐positive when PCR was negative (sensitivity 100%, specificity 99% compared to culture). PCR results were available within 24 h. Five infants were PCR+ and isolated meticillin‐sensitive Staphylococcus aureus. This organism gave a false‐positive PCR result. Two infants transferred in on broad‐spectrum antibiotics were PCR+ and negative by culture. Decolonization led to negative nasal PCR and culture in 4/5 infants to discharge. Conclusions: PCR methods are sensitive and specific for detection of MRSA colonization in newborn infants of all gestations with results 1–2 days before culture.