Identification of Infantile Diarrhea Caused by Breast Milk-Transmitted Staphylococcus aureus Infection

Staphylococcus aureus is a well-known organism which is responsible for a variety of human infectious diseases including skin infections, pneumonia, bacteremia, and endocarditis. Few of the microorganisms can be transmitted from mother to the newborn or infant by milk breastfeeding. This study aims to identify transmission of S. aureus from healthy, lactating mothers to their infants by breastfeeding. Stool specimens of diarrheal infants and breast milk of their mother (totally three pairs) were collected and six Staphylococcus aureus isolates were cultured positively. Homology and molecular characters of isolated strains were tested using pulsed-field gel electrophoresis (PFGE), spa typing, and multilocus sequence typing. Furthermore, toxin genes detection was also performed. Each pair of isolates has the same PFGE type and spa type. Four Sequence types (STs) were found among all the isolates; they are ST15, ST188, and ST59, respectively. Among the strains, seb, sec, and tst genes were found, and all were negative for pvl gene. The homology of the S. aureus strains isolated from the infants' stool and the mothers' milk was genetically demonstrated, which indicated that breastfeeding may be important in the transmission of S. aureus infection, and the character of S. aureus needed to be further evaluated.

What To Think If the Results of the National Institutes of Health Randomized Trial of Methicillin-ResistantStaphylococcus aureusand Vancomycin-ResistantEnterococcusControl Measures Are Negative (and Other Advice to Young Epidemiologists): A Review and an Au Revoir

The incidence of methicillin-resistantStaphylococcus aureus(MRSA) and vancomycin-resistantEnterococcus(VRE) infections continues to rise in National Nosocomial Infections Surveillance system hospitals, and these pathogens are reportedly causing more than 100,000 infections and many deaths each year in US healthcare facilities. This has led some to insist that control measures are now urgently needed, but several recent articles have suggested that isolation of patients does not work, is not needed, or is unsafe, or that a single cluster-randomized trial could be used to decide such matters. At least 101 studies have reported controlling MRSA infection and 38 have reported controlling VRE infection by means of active detection by surveillance culture and use of isolation for all colonized patients in healthcare settings where the pathogens are epidemic or endemic, in academic and nonacademic hospitals, and in acute care, intensive care, and long-term care settings. MRSA colonization and infection have been controlled to exceedingly low levels in multiple nations and in the state of Western Australia for decades by use of active detection and isolation. Studies suggesting problems with using such data to control MRSA colonization and infection have their own problems, which are discussed. Randomized trials are epidemiologic tools that can sometimes provide erroneous results, and they have not been considered necessary for studying isolation before it is used to control other important infections, such as tuberculosis, smallpox, and severe acute respiratory syndrome. No single epidemiologic study should be considered definitive. One should always weigh all available evidence. Infection with antibiotic-resistant pathogens such as MRSA and VRE is controllable to a low level by active detection and isolation of colonized and infected patients. Effective measures should be used to minimize the morbidity and mortality attributable to these largely preventable infections.

Management of Outbreaks of Methicillin-ResistantStaphylococcus aureusInfection in the Neonatal Intensive Care Unit: A Consensus Statement

Objective.

In 2002, the Chicago Department of Public Health (CDPH; Chicago, Illinois) convened the Chicago-Area Neonatal MRSA Working Group (CANMWG) to discuss and compare approaches aimed at control of methicillin-resistantStaphylococcus aureus(MRSA) in neonatal intensive care units (NICUs). To better understand these issues on a regional level, the CDPH and the Evanston Department of Health and Human Services (EDHHS; Evanston, Illinois) began an investigation.

Design.

Survey to collect demographic, clinical, microbiologic, and epidemiologic data on individual cases and clusters of MRSA infection; an additional survey collected data on infection control practices.

Setting.

Level III NICUs at Chicago-area hospitals.

Participants.

Neonates and healthcare workers associated with the level III NICUs.

Methods.

From June 2001 through September 2002, the participating hospitals reported all clusters of MRSA infection in their respective level III NICUs to the CDPH and the EDHHS.

Results.

Thirteen clusters of MRSA infection were detected in level III NICUs, and 149 MRSA-positive infants were reported. Infection control surveys showed that hospitals took different approaches for controlling MRSA colonization and infection in NICUs.

Conclusion.

The CANMWG developed recommendations for the prevention and control of MRSA colonization and infection in the NICU and agreed that recommendations should expand to include future data generated by further studies. Continuing partnerships between hospital infection control personnel and public health professionals will be crucial in honing appropriate guidelines for effective approaches to the management and control of MRSA colonization and infection in NICUs.

Transmission of Methicillin-ResistantStaphylococcus aureusto Preterm Infants Through Breast Milk

Objective:

To determine a potential source of MRSA colonization and infection among preterm infants in a neonatal intensive care unit (NICU) using molecular analysis of breast milk samples.

Design:

Case report, outbreak investigation.

Results:

Preterm triplets were delivered at 26 weeks' gestation via cesarean section when routine active surveillance for MRSA was performed for all infants in a NICU. Surveillance consisted of swabbing the throat, nose, and umbilicus (TNU) weekly. Although infants A and B initially had negative TNU swabs, repeat cultures were positive for MRSA on day of life (DOL) 10 and DOL 18, respectively. Surveillance and clinical cultures for infant C were negative. Infant A developed sepsis, and multiple blood cultures were positive for MRSA beginning on DOL 14. Infant B developed conjunctivitis and a conjunctival exudate culture was positive for MRSA on DOL 70. Both infants were fed breast milk via nasogastric tube. Cultures of breast milk samples for infants A and B dated prior to either infant's first positive surveillance culture were positive for MRSA. All MRSA isolates had identical results on antibiotic susceptibility testing. PFGE demonstrated identical banding patterns for the MRSA isolates from the blood culture of infant A, breast milk for infants A and B, and a surveillance swab from infant B. At no time did the mother develop evidence of mastitis or other local breast infection.

Conclusions:

MRSA can be passed from mother to preterm infant through contaminated breast milk, even in the absence of maternal infection. Colonization and clinical disease can result.

An investigation of the risk factors for infection with methicillin-resistant Staphylococcus aureus among patients in a neonatal intensive care unit

BACKGROUND

The aims of this study were to investigate the risk factors of methicillin-resistant Staphylococcus aureus (MRSA) infection among infants to establish effective infection control measures for neonatal intensive care unit (NICU).

METHODS

Data were prospectively collected from 961 infants hospitalized in a teaching hospital in Japan, from July 2002 through December 2005.

RESULTS

Among all infants, 28 (2.9%) developed MRSA infections. Multivariate logistic regression analyses demonstrated the risk factors for developing MRSA infections to include a low birth weight (odds ratio [OR], 0.91; 95% confidence interval [CI]: 0.93-0.99), the presence of eye mucous (OR, 6.78; 95% CI: 2.87-16.01), the practice of kangaroo mother care (OR, 3.82; 95% CI: 1.11-13.13), and the MRSA colonization rate (OR, 11.12; 95% CI: 1.32-93.89).

CONCLUSION

The risk factors for developing a MRSA infection among infants in NICU were a low birth weight, the presence of eye mucous, the practice of kangaroo mother care, and a high MRSA colonization rate. Therefore, extra attention should be given to infants in high-risk groups demonstrating a low birth weight and the presence of eye mucous and who have undergone kangaroo mother care. As a result, the cohort isolation of infants with MRSA may therefore be an effective strategy to prevent MRSA infections.

Cerebral abscess caused by Serratia marcescens in a premature neonate

BACKGROUND: Cerebral abscesses are extremely rare in neonates. Serratia marcescens is an unusual cause of sepsis and neurological spread is especially ominous. PURPOSE: To report the case of a 34-week neonate who developed this rare condition and to discuss diagnostic and therapeutic measures. CASE REPRT: A 34-week male neonate sequentially developed respiratory distress syndrome, early sepsis and necrotizing enterocolitis; later cultures revealed S. marcescens. After deterioration, a cerebral abscess became evident, which revealed S. marcescens. Clinical improvement ensued after high-dose amikacin and meropenem. CONCLUSION: Clinical signs are often non-specific. Proper diagnostic measures, neurosurgical consultation and aggressive antibiotic therapy are essential for these high-risk neonates.

Clustering of Serratia marcescens infections in a neonatal intensive care unit

OBJECTIVES

To study clusters of infections caused by Serratia marcescens in a neonatal intensive care unit (NICU) and to determine risk factors for S. marcescens infection or colonization.

DESIGN

Genotyping of S. marcescens isolates was performed by pulsed-field gel electrophoresis (PFGE). A retrospective case-control study was conducted.

SETTING

A tertiary-care pediatric hospital with a 16-bed NICU.

PATIENTS

All neonates with at least one culture positive for S. marcescens in the NICU during December 1999 to July 2002. Case-patients (n = 11) treated in the NICU during December 1999 to February 2000 were included in the case-control study. Neonates treated in the NICU for at least 72 hours during the same period with cultures negative for S. marcescens were used as control-patients (n = 27).

RESULTS

S. marcescens was cultured from 19 neonates; 9 were infected and 10 were colonized. PFGE analysis identified three epidemic strains; each cluster consisted of identical isolates, except one isolate in the first cluster that was different. The risk factors identified were low birth weight, prematurity, prolonged respiratory therapy, prolonged use of antibiotics, and maternal infection prior to delivery. Overcrowding and understaffing were recorded simultaneously with the clusters.

CONCLUSIONS

PFGE analysis showed three independent clusters. Several factors contributed to spread of the epidemic strains: (1) there were many severely premature and susceptible neonates, (2) the NICU was overcrowded during the clusters, and (3) transmission was likely to occur via the hands of staff. Cohorting and improvement of routine infection control measures led to the cessation of each cluster.

Effects of bifidobacterium breve supplementation on intestinal flora of low birth weight infants

BACKGROUND

It is known that the bifidobacteria flora play important roles in mucosal host defense and can prevent infectious diseases. Because bacterial populations develop during the first day of life, the authors examined whether the early administration of bifidobacteria has a positive effect on the health of low birth weight infants.

METHODS

The effects of oral administration of Bifidobacterium breve (B. breve) supplements were studied in a controlled trial with low birth weight infants (average birth weight 1489 g). The infants were divided into three groups: Group A and B received a dose of 1.6 x 10(8) cells of B. breve supplement twice a day, commencing either from several hours after birth (group A) or 24 h after birth (group B). Group C, the control group, received no supplement.

RESULTS

There were no significant differences in birth weight, treatment with antibiotics, and the starting time of breast-feeding among the three groups. A Bifidobacterium-predominant flora was formed at an average of 2 weeks after birth in group A and at an average of 4 weeks after birth in group B, while no Bifidobacterium was isolated in eight out of 10 infants in group C during the observation period of 7 weeks. In comparison between group A and B, Bifidobacterium was detected significantly earlier in group A, and the number of Enterobacteriaceae present in the infants at 2 weeks after birth was significantly lower in group A.

CONCLUSION

The results of the present study suggest that very early administration of B. breve to low birth weight infants is useful in promoting the colonization of the Bifidobacterium and the formation of a normal intestinal flora.

An outbreak of methicillin-resistant Staphylococcus aureus in a neonatal intensive care unit

OBJECTIVE

To describe the epidemiologic and molecular investigations that successfully contained an outbreak of methicillin-resistant Staphylococcus aureus (MRSA) in a neonatal intensive care unit (NICU).

DESIGN

Isolates of MRSA were typed by pulsed-field gel electrophoresis (PFGE) and S. aureus protein A (spa).

SETTING

A level III-IV, 45-bed NICU located in a children's hospital within a medical center.

PATIENTS

Incident cases had MRSA isolated from clinical cultures (eg, blood) or surveillance cultures (ie, anterior nares).

INTERVENTIONS

Infected and colonized infants were placed on contact precautions, cohorted, and treated with mupirocin. Surveillance cultures were performed for healthcare workers (HCWs). Colonized HCWs were treated with topical mupirocin and hexachlorophene showers.

RESULTS

From January to March 2001, the outbreak strain of MRSA, PFGE clone B, was harbored by 13 infants. Three (1.3%) of 235 HCWs were colonized with MRSA. Two HCWs, who rotated between the adult and the pediatric facility, harbored clone C. One HCW, who exclusively worked in the children's hospital, was colonized with clone B. From January 1999 to November 2000, 22 patients hospitalized in the adult facility were infected or colonized with clone B. Spa typing and PFGE yielded concordant results. PFGE clone B was identified as spa type 16, associated with outbreaks in Brazil and Hungary.

CONCLUSIONS

A possible route of MRSA transmission was elucidated by molecular typing. MRSA appears to have been transferred from our adult facility to our pediatric facility by a rotating HCW. Spa typing allowed comparison of our institution's MRSA strains with previously characterized outbreak clones.

Outbreak of invasive disease caused by methicillin-resistant Staphylococcus aureus in neonates and prevalence in the neonatal intensive care unit

OBJECTIVES

To describe an outbreak of severe invasive disease caused by methicillin-resistant Staphylococcus aureus (MRSA) and the epidemiology of MRSA in a neonatal intensive care unit during a 12-yr period from 1989 to 2001.

SETTING

A 40-bed, level III neonatal intensive care unit at a children's hospital that admits approximately 450 neonates each year from about 35 neighboring hospitals.

PATIENTS

All neonates infected or colonized with MRSA during the outbreak are described. All cases of MRSA infection or colonization in the neonatal intensive care unit from 1989 to 2001 were identified from the database maintained by the hospital epidemiology program.

RESULTS

During the outbreak, 12 neonates were infected or colonized with MRSA, 11 of whom had the epidemic strain. Seven of these 11 neonates had invasive disease, including bacteremia, meningitis, or urinary tract infection, and four neonates were colonized with the epidemic strain. This outbreak was difficult to control by routine epidemiologic measures, and additional control measures, including closing the neonatal intensive care unit to new admissions and treating all infants with intranasal mupirocin, were implemented. Since the outbreak, the prevalence of MRSA in the neonatal intensive care unit has remained low.

CONCLUSIONS

MRSA outbreaks in neonatal intensive care units can be prolonged. Aggressive infection-control measures are often necessary to terminate these outbreaks. Such efforts are essential because MRSA infections in premature neonates can cause significant morbidity and mortality.

An outbreak of Serratia marcescens bacteremia after general anesthesia

OBJECTIVE

To investigate an outbreak of Serratia marcescens bacteremia among patients after general anesthesia.

DESIGN

A case-control study.

SETTING

A 304-bed, pediatric teaching hospital.

PATIENTS

Twenty-three pediatric patients who developed S. marcescens bacteremia within 2 weeks after general anesthesia between June 15 and September 22, 1999, were compared with 46 age-matched control-patients who had undergone procedures on the same clinical services of the hospital during the same period.

RESULTS

Cases were distributed over a wide range of surgical services and were not correlated with exposure to any of the surgical, anesthesia, or nursing staff. Case-patients were significantly more likely than control-patients to have received cefazolin (odds ratio [OR], 11.1; 90% confidence interval [CI90], 1.9 to 24.3) or to have had perioperative placement of a central vascular catheter (OR, 4.2; CI90, 1.2 to 18.8). The timing of the procedures of patients who subsequently developed S. marcescens bacteremia was significantly associated with the shifts of one or more of five operating room technicians (OR, 2.9 to 6.8) who were responsible for preparing intravenous fluids used both to reconstitute perioperatively administered antibiotics and to prime central vascular catheter assemblies.

CONCLUSIONS

Our findings are consistent with a pattern of intermittent contamination due to periodic breaches in sterile technique, rather than a point-source of contamination. The unique challenges that such a procedural breakdown presents to an epidemiologic investigation are discussed. This outbreak stresses the importance of providing comprehensive training in antisepsis when multifunctional personnel are incorporated into an operating room work environment.

Epidemiology of methicillin-susceptible Staphylococcus aureus in the neonatal intensive care unit

OBJECTIVE

When the incidence of methicillin-susceptible Staphylococcus aureus (MSSA) infection or colonization increased in our neonatal intensive care unit (NICU), we sought to further our understanding of the relationship among colonization with MSSA, endemic infection, and clonal spread.

DESIGN

A retrospective cohort study was used to determine risk factors for acquisition of a predominant clone of MSSA (clone "B").

SETTING

A 45-bed, university-affiliated, level III-IV NICU.

PATIENTS

Infants hospitalized in the NICU from October 1999 to September 2000.

INTERVENTIONS

Infection control strategies included surveillance cultures of infants, cohorting infected or colonized infants, contact precautions, universal glove use, mupirocin treatment of the anterior nares of all infants in the NICU, and a hexachlorophene bath for infants weighing 1,500 g or more.

RESULTS

During the 1-year study period, three periods of increased incidence of MSSA colonization or infection, ranging from 6.4 to 13.5 cases per 1,000 patient-days per month, were observed. Molecular typing using pulsed-field gel electrophoresis demonstrated two predominant clones, clone "B" and clone "G," corresponding to two periods of increased incidence. Multivariate analysis demonstrated that length of stay (OR, 1.035; 95% confidence interval [CI95], 1.008 to 1.062; P = .010) increased risk per day) and the use of H2-blockers (OR, 20.44; CI95, 2.48 to 168.26; P = .005) were risk factors for either colonization or infection with clone "B," and that the use of peripheral catheters was protective (OR, 0.06; CI95, 0.01 to 0.43; P= .005).

CONCLUSIONS

Control of MSSA represents unique challenges as colonization is expected, endemic infections are tolerated, and surveillance efforts generally focus on multidrug-resistant pathogens. Future studies should address cost-effective surveillance strategies for endemic infections.

Nosocomial outbreak of Serratia marcescens in a neonatal intensive care unit

OBJECTIVES

To investigate and describe an outbreak of Serratia marcescens in a neonatal intensive care unit (NICU) and to report the interventions leading to cessation of the outbreak.

SETTING

A 2,168-bed, tertiary-care, university teaching hospital in Vienna, Austria, with an 8-bed NICU.

DESIGN

We conducted a case-control study to identify risk factors for colonization and infection with S. marcescens. A case-patient was defined as any neonate in the NICU with a positive culture for S. marcescens between October 1, 2000, and February 28, 2001. Polymerase chain reaction was applied to type isolates.

METHODS

During unannounced observations, the NICU was examined and existing policies were reviewed. Staff were reinstructed in hand antisepsis and gloving policies. Admissions were halted on December 27. During previously planned technical maintenance of the ward, the NICU was closed for 10 days and thorough aldehyde-based disinfection of the NICU was performed.

RESULTS

Ten neonates met the case definition: 6 with infections (among them 3 with cerebral abscesses) and 4 with asymptomatic colonization. Previous antibiotic treatment of the mothers with cefuroxime was the single significant risk factor for colonization or infection (P = .028; odds ratio, 17; 95% confidence interval, 1.3 to 489.5).

CONCLUSIONS

S. marcescens can cause rapidly spreading outbreaks associated with fatal infections in NICUs. With aggressive infection control measures, such outbreaks can be stopped at an early stage. Affected neonates themselves may well be the source of cross-infection to other patients on the ward. Antibiotic treatment of mothers should be reevaluated to avoid unnecessary exposure to antibiotics with the potential of over-growth of resistant organisms.

A rapid and easy PCR-RFLP method for genotyping Serratia marcescens strains isolated in different hospital outbreaks and patient environments in the Lyon area, France

A new genotyping method for Serratia marcescens is described. This method uses the flagellin gene as target for polymerase chain reaction amplification and Alu I restriction fragment length polymorphism. The strains tested belonged to 13 different hospital clusters of S. marcescens isolated between 1983 and 1988, concerning outbreaks and/or patient environments in different hospital units in Lyon and the Rhone-Alpes region of France. Initially, the classification had been performed by marcescinotyping. These strains were then tested by ribotyping and genotyping of the flagellin gene. Genotyping showed similar classification to ribotyping. The genotyping method is the easiest technique, as reproducible as ribotyping, and with almost the same ability to discriminate different strains. It does not need expensive equipment, is more rapid, and is less labor intensive than ribotyping. With this method, all strains of S. marcescens including sporadic isolates could be amplified and typed. Antibiotic sensitivity determination was found to be a useful complementary and confirmation test for all these typing methods.

Three consecutive outbreaks of Serratia marcescens in a neonatal intensive care unit

We investigated an outbreak of Serratia marcescens in the neonatal intensive care unit (NICU) of the University Hospital of Zurich. S. marcescens infection was detected in 4 children transferred from the NICU to the University Children's Hospital (Zurich). All isolates showed identical banding patterns by pulsed-field gel electrophoresis (PFGE). In a prevalence survey, 11 of 20 neonates were found to be colonized. S. marcescens was isolated from bottles of liquid theophylline. Despite replacement of these bottles, S. marcescens colonization was detected in additional patients. Prospective collection of stool and gastric aspirate specimens revealed that colonization occurred in some babies within 24 hours after delivery. These isolates showed a different genotype. Cultures of milk from used milk bottles yielded S. marcescens. These isolates showed a third genotype. The method of reprocessing bottles was changed to thermal disinfection. In follow-up prevalence studies, 0 of 29 neonates were found to be colonized by S. marcescens. In summary, 3 consecutive outbreaks caused by 3 genetically unrelated clones of S. marcescens could be documented. Contaminated milk could be identified as the source of at least the third outbreak.

Molecular epidemiology of an outbreak of Serratia marcescens in a neonatal intensive care unit

OBJECTIVE

To investigate and control a biphasic outbreak of Serratia marcescens in a neonatal intensive care unit (NICU).

DESIGN

Epidemiological and laboratory investigation of the outbreak.

SETTING

The NICU of the 1,470-bed teaching hospital of the University "Federico II," Naples, Italy.

PATIENTS

The outbreak involved 56 cases of colonization by S marcescens over a 15-month period, with two epidemic peaks of 6 and 3 months, respectively. Fourteen (25%) of the 56 colonized infants developed clinical infections, 50% of which were major (sepsis, meningitis, or pneumonia).

METHODS

Epidemiological and microbiological investigations, analysis of macrorestriction pattern of genomic DNA through pulsed-field gel electrophoresis (PFGE) of clinical and environmental isolates, and institution of infection control measures.

RESULTS

Analysis of macrorestriction patterns of genomic DNA by PFGE demonstrated that the vast majority of S marcescens isolates, including three environmental strains isolated from two handwashing disinfectants and the hands of a nurse, were of the same clonal type. The successful control of the outbreak was achieved through cohorting of noncolonized infants, isolation of S marcescens-infected and -colonized infants, and an intense educational program that emphasized the need for adherence to glove use and handwashing policies. The NICU remained open to new admissions.

CONCLUSIONS

Outbreaks caused by S marcescens are very difficult to eradicate. An infection control program that includes molecular typing of microorganisms and the proper dissemination among staff members of the typing results is likely to be very effective in reducing NICU-acquired infections and in controlling outbreaks caused by S marcescens, as well as other multiresistant bacteria.

Outbreak of Serratia marcescens infection in a neonatal intensive care unit

We report an outbreak of Serratia marcescens infection in the neonatal intensive care unit of a community hospital. The outbreak involved eight neonates, (five infected and three colonized), one of whom died. Pulsed-field gel electrophoresis confirmed that all isolates were identical strains. Cohorting and isolation of the infected neonates helped to control the outbreak. No environmental source of infection was found.

Intensive care unit design and environmental factors in the acquisition of infection

The incidence of infection in the intensive care unit (ICU) is one of the highest in the hospital and yet facilities to prevent infection are often inadequate in this important clinical area. Many antibiotic-resistant bacteria such as methicillin-resistant Staphylococcus aureus (MRSA), Serratia marcescens and vancomycin-resistant enterococci (VRE), may survive and persist in the environment leading to recurrent outbreaks. A number of professional and scientific bodies in the UK, the USA and Europe have published guidelines on the design and layout of ICUs. All emphasize the importance of adequate isolation facilities (at least one cubicle for every six beds), sufficient space around each bed (20 m2), wash hand basins between every other bed, ventilation including positive and negative pressure ventilation for high risk patients and sufficient storage and utility space. Common sense and considerations of safety and comfort should guide decisions on floors, walls etc. Appropriate cleaning and disinfection programmes are essential to render the ICU relatively pathogen free and compliance with handwashing is imperative in minimizing infection in this high-risk area. Infection control teams should support ICU personnel in their efforts to upgrade facilities and help ensure that this is a priority when resources are limited.