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1.  Coagulase-Negative Staphylococcal Skin Carriage among Neonatal Intensive Care Unit Personnel: from Population to Infection▿  
Journal of Clinical Microbiology  2010;48(11):3876-3881.
Coagulase-negative staphylococci (CoNS) are a major cause of sepsis in neonatal intensive care units (NICU) worldwide. Infecting strains of these commensal bacteria may originate from NICU personnel. Therefore, we studied the characteristics of CoNS isolates from NICU personnel and compared them to those of isolates from the general population and from sepsis patients. Furthermore, we studied the epidemiological effect on CoNS carriage of NICU personnel after a period of absence. In our study, we isolated CoNS from the thumbs of NICU personnel every 2 weeks during the summer of 2005 and sampled personnel returning from vacation and a control group from the general population. Furthermore, we collected sepsis isolates from this period. Isolates were tested for antibiotic resistance, mecA and icaA carriage, biofilm production, and genetic relatedness. We found that mecA and icaA carriage as well as penicillin, oxacillin, and gentamicin resistance were significantly more prevalent in CoNS strains from NICU personnel than in community isolates. Similar trends were observed when postvacation strains were compared to prevacation strains. Furthermore, genetic analysis showed that 90% of the blood isolates were closely related to strains found on the hands of NICU personnel. Our findings revealed that CoNS carried by NICU personnel differ from those in the general population. Hospital strains are replaced by community CoNS after a period of absence. NICU personnel are a likely cause for the cross-contamination of virulent CoNS that originate from the NICU to patients.
PMCID: PMC3020886  PMID: 20826641
2.  Molecular Epidemiology of Coagulase-Negative Staphylococci Causing Sepsis in a Neonatal Intensive Care Unit over an 11-Year Period 
Journal of Clinical Microbiology  2004;42(3):992-995.
Coagulase-negative staphylococci (CoNS) are the major causative microorganisms in neonatal nosocomial sepsis. Previous studies have shown that CoNS sepsis in the neonatal intensive care unit (NICU) is caused by predominant molecular types that are widely distributed among both neonates and staff. Some of these molecular types may persist in the NICU for years. The purpose of the present study was to determine the dynamic behavior of CoNS strains causing sepsis over a prolonged period of time by determining the molecular types of all blood isolates from septicemic infants over a period of 11 years (1991 to 2001). The results show that neonatal CoNS sepsis is increasingly caused by a few predominant molecular clusters. The most striking finding was that in recent years one molecular cluster emerged as the predominant cause of neonatal CoNS sepsis, responsible for no less than 31% (20 of 65) of blood isolates in 2001. Antibiotic resistance, particularly beta-lactam resistance, is probably an important selective force considering the high mecA gene carriage of CoNS blood isolates (70 to 92%). We conclude that neonatal CoNS sepsis is increasingly caused by a limited number of predominant molecular CoNS types and that antibiotic resistance is probably a major selective force.
PMCID: PMC356815  PMID: 15004043
3.  Coagulase-negative staphylococcal infections in a neonatal intensive care unit: In vivo response to cloxacillin 
Paediatrics & Child Health  2006;11(10):659-663.
Following the introduction of cloxacillin and gentamicin as the first line of treatment for possible late-onset sepsis (LOS) in the authors’ neonatal intensive care unit (NICU), it was subsequently noted that very low birth weight (VLBW) infants improved clinically, despite subsequently positive blood cultures for oxacillin-resistant, coagulase-negative Staphylococcus (CONS). The results of the management of VLBW infants with CONS sepsis during one calendar year, based on clinical rather than laboratory findings, are presented.
VLBW infants with LOS were identified through the neonatal database, and the charts of those with CONS were reviewed for antibiotic usage, antibiotic resistance pattern, clearance of CONS from the blood and NICU discharge status. Oxacillin sensitivity was determined by the presence of the mecA gene.
From January 1 to December 31, 2002, 27 VLBW infants, treated in the authors’ NICU for LOS due to CONS, were identified. The mean age of LOS infants with CONS was 15 days (median 12 days; range three to 54 days), the mean birth weight (± SD) was 904±247 g, and the mean gestational age at birth (± SD) was 27±2 weeks. All infants were started on cloxacillin and gentamicin, and improved clinically over the first 48 h. Six isolates were sensitive to cloxacillin. Twenty-three infants grew oxacillin-resistant CONS, eight of whom had persistence of CONS on repeat culture secondary to central lines. Two infants grew two strains of CONS. Eighteen of 22 infants (82%) with in vitro oxacillin-resistant CONS had clearance of bacteremia with cloxacillin and gentamicin. Ten infants (37%) received vancomycin, based on the authors’ guidelines. There were no cases of prolonged bacteremia requiring rifampicin. Three infants died, but none of the deaths could be attributed to CONS.
The authors describe clinical improvement with clearance of CONS using cloxacillin and gentamicin, despite laboratory results suggesting oxacillin resistance. The authors’ unit policy was based on clinical response and permitted the continuation of cloxacillin, provided that a repeat blood culture was negative. Vancomycin use was suggested for clinical deterioration or persistence of CONS. These results question the in vitro tests of resistance. Clearance of oxacillin-resistant CONS from the blood points to in vivo sensitivity, while the laboratory testing suggests in vitro resistance. The absence of subsequent positive blood cultures for CONS confirms clearance of this organism.
It was demonstrated that cloxacillin (150 mg/kg/day dose), along with gentamicin, can clear CONS from the blood within 48 h. The relationship between in vivo and in vitro sensitivities also needs to be further studied both in the laboratory and in a prospective trial.
PMCID: PMC2528592  PMID: 19030249
Antibiotic sensitivities; Coagulase-negative staphylococcal bacteremia; Very low birth weight
4.  The ica Operon and Biofilm Production in Coagulase-Negative Staphylococci Associated with Carriage and Disease in a Neonatal Intensive Care Unit 
Journal of Clinical Microbiology  2002;40(2):382-388.
Coagulase-negative staphylococci (CoNS) are a major cause of sepsis in the neonatal intensive care unit (NICU). We evaluated the hypothesis that the ica operon and biofilm production are associated with CoNS disease in this setting. CoNS associated with bacteremia or blood culture contamination and from the skin of infants with CoNS bacteremia or healthy controls were obtained during a prospective case-control study on a busy NICU. A total of 180 strains were identified, of which 122 (68%) were Staphylococcus epidermidis and the remainder were S. capitis (n = 29), S. haemolyticus (n = 11), S. hominis (n = 9), S. warneri (n = 8), and S. auricularis (n = 1). The presence of the genes icaA, icaB, icaC, and icaD was determined by PCR, and biofilm production was examined using qualitative (Congo red agar [CRA]) and quantitative (microtiter plate) techniques. There were no significant differences in the presence of the ica operon or CRA positivity among the four groups of strains. However, quantitative biofilm production was significantly greater in strains isolated from either the blood or the skin of neonates with S. epidermidis bacteremia. We conclude that the quantity of biofilm produced may be associated with the ability to cause CoNS infection. This conclusion suggests that the regulation of biofilm expression may play a central role in the disease process.
PMCID: PMC153361  PMID: 11825946
5.  Nosocomial Spread of a Staphylococcus capitis Strain with Heteroresistance to Vancomycin in a Neonatal Intensive Care Unit 
Journal of Clinical Microbiology  2002;40(7):2520-2525.
A premature infant in a neonatal intensive care unit (NICU) developed a bloodstream infection caused by coagulase-negative staphylococci (CoNS) sensitive to vancomycin. The infection persisted for 3 weeks, despite therapy with vancomycin and replacement of all intravenous catheters. The neonate died due to necrotizing enterocolitis which developed during the ongoing sepsis. We screened this strain and 216 other strains of CoNS from cultures of blood obtained from neonates between 1997 and 2000 for heteroresistance to vancomycin. Forty-eight isolates, including the strain that caused ongoing sepsis, proved heteroresistant. All isolates were identified as Staphylococcus capitis and were identical, just as their resistant stable subcolonies were, when they were genetically fingerprinted by amplified-fragment length polymorphism analysis. The heteroresistant phenotype of this endemic strain was confirmed by population analysis. We conclude that heteroresistance to vancomycin occurs in S. capitis and might be the cause of therapeutic failures in NICUs. Moreover, heteroresistant strains can become endemic in such units.
PMCID: PMC120592  PMID: 12089273
6.  Persistence of Clones of Coagulase-Negative Staphylococci among Premature Neonates in Neonatal Intensive Care Units: Two-Center Study of Bacterial Genotyping and Patient Risk Factors 
Journal of Clinical Microbiology  1998;36(9):2485-2490.
From 1 January 1995 until 1 January 1996, we studied the molecular epidemiology of blood isolates of coagulase-negative staphylococci (CoNS) in the Neonatal Intensive Care Units (NICUs) of the Sophia Children’s Hospital (SCH; Rotterdam, The Netherlands) and the Wilhelmina Children’s Hospital (WCH; Utrecht, The Netherlands). The main goal of the present study was to detect putatively endemic clones of CoNS persisting in these NICUs. Pulsed-field gel electrophoresis was used to detect the possible presence of endemic clones of clinical significance. In addition, clinical data of patients in the SCH were analyzed retrospectively to identify risk factors for the acquisition of positive blood cultures. In both centers, endemic CoNS clones were persistently present. Thirty-three percent of the bacterial isolates derived from blood cultures in the SCH belonged to a single genotype. In the WCH, 45% of all bacterial strains belonged to a single clone. These clones were clearly different from each other, which implies that site specificity is involved. Interestingly, we observe that the clonal type in the SCH differed significantly from the incidentally occurring strains with respect to both the average pH and partial CO2 pressure of the patient’s blood at the time of bacterial culture. We found that the use of intravascular catheters, low gestational age, and a long hospital stay were important risk factors for the development of a putative CoNS infection. When the antibiotic susceptibility of the bacterial isolates was assessed, a clear correlation between the nature of the antibiotics most frequently used as a first line of defense versus the resistance profile was observed. We conclude that the intensive use of antibiotics in an NICU setting with highly susceptible patients causes selection of multiresistant clones of CoNS which subsequently become endemic.
PMCID: PMC105149  PMID: 9705379
7.  Use of rifampin in persistent coagulase negative staphylococcal bacteremia in neonates 
BMC Pediatrics  2010;10:84.
Coagulase negative staphylococci (CoNS) are the most common cause of neonatal sepsis in the Neonatal Intensive Care Unit (NICU). A minority of neonates does not respond to vancomycin therapy and develops persistent bacteremia, which may be treated with rifampin. We evaluated the use of rifampin in persistent CoNS bacteremia.
Retrospective study of 137 neonates with CoNS bacteremia during admission to a tertiary NICU between July 2006 and July 2009. Main outcome measures were total duration of bacteremia and the adequacy of vancomycin and rifampin therapy.
137/1696 (8.0%) neonates developed a CoNS bacteremia. Eighteen were treated with rifampin because of persistent bacteremia (3 positive blood cultures at least 48 hours apart with clinical symptoms) or (a serious suspicion of) an intravascular thrombus. Duration of bacteremia prior to rifampin therapy (8.0 ± 3.6 days) was positively correlated (p < 0.001) to the total duration of bacteremia (10.3 ± 3.7 days). After starting rifampin therapy C-reactive protein (CRP) levels of all neonates declined and blood cultures became sterile after 2.3 ± 1.6 days. Vancomycin levels were not consistently measured in all neonates, resulting in late detection of subtherapeutic trough levels.
Rifampin may be effective in the treatment of persistent CoNS infections in neonates. Outcome may be improved by adequate monitoring of vancomycin trough levels.
PMCID: PMC2994847  PMID: 21092087
8.  Cloxacillin versus vancomycin for presumed late-onset sepsis in the Neonatal Intensive Care Unit and the impact upon outcome of coagulase negative staphylococcal bacteremia: a retrospective cohort study 
BMC Pediatrics  2005;5:49.
Coagulase negative staphylococcus (CONS) is the main cause of late-onset sepsis in Neonatal Intensive Care Units (NICU). Although CONS rarely causes fulminant sepsis, vancomycin is frequently used as empiric therapy. Indiscriminate use of vancomycin has been linked to the emergence of vancomycin resistant organisms. The objective of this study was to compare duration of CONS sepsis and mortality before and after implementation of a policy of selective vancomycin use and compare use of vancomycin between the 2 time periods.
A retrospective study was conducted of infants ≥4 days old, experiencing signs of sepsis with a first positive blood culture for CONS, during two 12-month periods. Late-onset sepsis was treated empirically with vancomycin and gentamicin during period 1, and cloxacillin and gentamicin during period 2. The confidence interval method was used to assess non-inferiority of the outcomes between the two study groups.
There were 45 episodes of CONS sepsis during period 1 and 37 during period 2. Duration of sepsis was similar between periods (hazard ratio of 1.00, 95%CI: 0.64, 1.57). One death during period 2 was possibly related to CONS sepsis versus none in period 1. Vancomycin was used in 97.8% of episodes in period 1 versus 81.1% of episodes in period 2.
Although we failed to show non-inferiority of duration of sepsis in the cloxacillin and gentamicin group compared to the vancomycin and gentamicin group, duration of sepsis was clinically similar. Restricting vancomycin for confirmed cases of CONS sepsis resistant to oxacillin appears effective and safe, and significantly reduces vancomycin use in the NICU.
PMCID: PMC1343548  PMID: 16375769
9.  Sepsis in Young Infants with Congenital Heart Disease 
Early human development  2012;88(Suppl 2):S92-S97.
We sought to describe the incidence, pathogen distribution, and mortality associated with blood culture-proven sepsis in young infants with congenital heart disease (CHD) admitted to a neonatal intensive care unit (NICU).
Cohort study of all blood cultures obtained from infants with CHD between 4 and 120 days of age cared for in250 NICUs managed by the Pediatrix Medical Group in the United States between 1996 and 2007.
Of 11,638 infants with CHD, 656 (6%) had 821 episodes of sepsis: a cumulative incidence of 71/1000 admissions. Gram-positive organisms were the most common cause (64%), and coagulase-negative Staphylococcus and Staphylococcus aureus were the most frequently isolated species. On multivariable regression, infants with sepsis were more likely to die compared to infants with sterile blood cultures (odds ratio [OR] = 1.53 [95% confidence interval: 1.09, 2.13]). Infants with gram-negative bacteremia and candidemia were more likely to die than infants with sterile blood cultures (OR = 2.01 [1.20, 3.37], and OR = 3.18 [1.60, 6.34], respectively).
Infants with CHD have a high incidence of culture-proven sepsis, especially with staphylococcal organisms. Gram-negative bacteremia and candidemia are strongly associated with increased mortality in this group of young infants.
PMCID: PMC3513769  PMID: 22633525
infant; sepsis; infection; congenital heart disease; epidemiology; outcomes
10.  Methicillin-Resistant Staphylococcus capitis with Reduced Vancomycin Susceptibility Causes Late-Onset Sepsis in Intensive Care Neonates 
PLoS ONE  2012;7(2):e31548.
Coagulase-negative staphylococci, mainly Staphylococcus epidermidis, are the most frequent cause of late-onset sepsis (LOS) in the neonatal intensive care unit (NICU) setting. However, recent reports indicate that methicillin-resistant, vancomycin-heteroresistant Staphylococcus capitis could emerge as a significant pathogen in the NICU. We investigated the prevalence, clonality and vancomycin susceptibility of S. capitis isolated from the blood of NICU infants and compared these data to adult patients.
Methodology/Principal Findings
We conducted a retrospective laboratory-based survey of positive blood cultures in NICU infants ≥3 days of age (n = 527) and in adult ICU patients ≥18 years of age (n = 1473) who were hospitalized from 2004 to 2009 in two hospital centers in Lyon, France. S. capitis was the most frequent pathogen in NICU infants, ahead of S. epidermidis (39.1% vs. 23.5% of positive blood cultures, respectively). Conversely, S. capitis was rarely found in adult ICU patients (1.0%) compared to S. epidermidis (15.3%). S. capitis bloodstream isolates were more frequently resistant to methicillin when collected from NICU infants than from adult patients (95.6% vs. 53.3%, respectively). Furthermore, we collected and characterized 53 S. capitis bloodstream isolates from NICU infants and adult patients from six distant cities. All methicillin-resistant S. capitis isolates from NICU infants were clonally related as determined by pulsed-field gel electrophoresis. These isolates harbored a type V-related staphylococcal chromosomal cassette mec element, and constantly showed either vancomycin resistance (37.5%) or heteroresistance (62.5%). Conversely, the isolates that were collected outside of the NICU were genetically diverse and displayed much lower rates of vancomycin resistance and heteroresistance (7.7% and 23.1%, respectively).
A clonal population of methicillin-resistant S. capitis strains has spread into several French NICUs. These isolates exhibit reduced susceptibility to vancomycin, which is the most widely used antimicrobial agent in the NICU setting.
PMCID: PMC3279402  PMID: 22348102
11.  Decreased Vancomycin Susceptibility of Coagulase-Negative Staphylococci in a Neonatal Intensive Care Unit: Evidence of Spread of Staphylococcus warneri 
Journal of Clinical Microbiology  2003;41(10):4660-4665.
Coagulase-negative staphylococci (CoNS) are important pathogens in premature neonates; decreasing glycopeptide susceptibility has been observed among these isolates. The epidemiology of colonization with CoNS, the organisms' vancomycin susceptibilities, and genetic relatedness were studied over 6 months in a tertiary-care neonatal unit. A total of 321 isolates of CoNS were isolated. Seventy-five percent of the infants were colonized at admission, and virtually all were colonized thereafter. Common species were Staphylococcus epidermidis (69%), S. warneri (12%), S. haemolyticus (9.7%), and S. hominis (5.6%). A total of 3.9% of CoNS isolates had decreased vancomycin susceptibility (DVS) (MICs > 2.0 μg/ml); isolate recovery was associated with a stay in a neonatal intensive care unit for >28 days (P = 0.039), vancomycin exposure (P = 0.021), and S. warneri colonization (P < 0.0001). Nine of 12 (75%) CoNS with DVS were S. warneri, had enhanceable high-level resistance in vitro, were indistinguishable or closely related by pulsed-field gel electrophoresis, and were different from 29 vancomycin-susceptible S. warneri isolates. Epidemiological analysis suggested unsuspected nosocomial spread. Species determination in certain settings may aid in the understanding of emerging nosocomial problems.
PMCID: PMC254305  PMID: 14532199
12.  Serious infection in a neonatal intensive care unit: a two-year survey. 
The Journal of Hygiene  1985;95(2):289-297.
Over a two-year period 160 episodes of serious infection occurred in 139 infants admitted to a regional neonatal intensive-care unit. Eighty-seven (26%) of very low birth weight (VLBW) neonates and 52 (8%) of infants of birth weight greater than 1500 g were infected. The majority (84%) had bacteraemia alone. Though the clinical features of infection were not distinctive, in 94% of episodes the peripheral white blood cell or band counts were abnormal. Thirty-three (21%) of the infections occurred in infants under 48 h old and 15 of these followed prolonged rupture of membranes (greater than 48 h). All of the infections due to group B streptococci (5), Streptococcus viridans (2) and Haemophilus influenzae (3) occurred in this group. Coagulase-negative staphylococci (CONS) accounted for 49% of the infections and there was a marked increase in incidence of such infections during the survey. Infections with CONS were not necessarily associated with parenteral nutrition, the presence of intra-arterial catheters or mechanical ventilation but the rise in incidence was coincident with change in skin disinfectant usage and the general use of a third-generation cephalosporin to which the CONS were resistant. Although VLBW infants with meningitis were more likely to die than those of higher birthweight, the risk for those with bacteriaemia was the same in both groups. Infants with CONS sepsis were less likely to die than those with infections due to Gram-negative bacteria and the time from onset of infection to death was significantly longer for the former.
PMCID: PMC2129542  PMID: 4067290
13.  Catheter-related bloodstream infections in neonatal intensive care units 
Korean Journal of Pediatrics  2011;54(9):363-367.
Central venous catheters (CVCs) are regularly used in intensive care units, and catheter-related bloodstream infection (CRBSI) remains a leading cause of healthcare-associated infections, particularly in preterm infants. Increased survival rate of extremely-low-birth-weight infants can be partly attributed to routine practice of CVC placement. The most common types of CVCs used in neonatal intensive care units (NICUs) include umbilical venous catheters, peripherally inserted central catheters, and tunneled catheters. CRBSI is defined as a laboratory-confirmed bloodstream infection (BSI) with either a positive catheter tip culture or a positive blood culture drawn from the CVC. BSIs most frequently result from pathogens such as gram-positive cocci, coagulase-negative staphylococci, and sometimes gram-negative organisms. CRBSIs are usually associated with several risk factors, including prolonged catheter placement, femoral access, low birth weight, and young gestational age. Most NICUs have a strategy for catheter insertion and maintenance designed to decrease CRBSIs. Specific interventions slightly differ between NICUs, particularly with regard to the types of disinfectants used for hand hygiene and appropriate skin care for the infant. In conclusion, infection rates can be reduced by the application of strict protocols for the placement and maintenance of CVCs and the education of NICU physicians and nurses.
PMCID: PMC3250601  PMID: 22232628
Catheter; Bacteremia; Intensive care units; Newborn
14.  Molecular Epidemiology of Staphylococcus epidermidis in a Neonatal Intensive Care Unit over a Three-Year Period 
Journal of Clinical Microbiology  2000;38(5):1740-1746.
Coagulase-negative staphylococci, especially Staphylococcus epidermidis, are increasingly important nosocomial pathogens, particularly in critically ill neonates. A 3-year prospective surveillance of nosocomial infections in a neonatal intensive care unit (NICU) was performed by traditional epidemiologic methods as well as molecular typing of microorganisms. The aims of the study were (i) to quantify the impact of S. epidermidis on NICU-acquired infections, (ii) to establish if these infections are caused by endemic clones or by incidentally occurring bacterial strains of this ubiquitous species, (iii) to evaluate the use of different methods for the epidemiologic typing of the isolates, and (iv) to characterize the occurrence and the spread of staphylococci with decreased glycopeptide susceptibility. Results confirmed that S. epidermidis is one of the leading causes of NICU-acquired infections and that the reduced glycopeptide susceptibility, if investigated by appropriate detection methods such as population analysis, is more common than is currently realized. Typing of isolates, which can be performed effectively through molecular techniques such as pulsed-field gel electrophoresis but not through antibiograms, showed that many of these infections are due to clonal dissemination and, thus, are potentially preventable by strict adherence to recommended infection control practices and the implementation of programs aimed toward the reduction of the unnecessary use of antibiotics. These strategies are also likely to have a significant impact on the frequency of the reduced susceptibility of staphylococci to glycopeptides, since this phenomenon appears to be determined either by more resistant clones transmitted from patient to patient or, to a lesser extent, by strains that become more resistant as a result of antibiotic pressure.
PMCID: PMC86575  PMID: 10790091
15.  Surface Microbes in the Neonatal Intensive Care Unit: Changes with Routine Cleaning and over Time 
Journal of Clinical Microbiology  2013;51(8):2617-2624.
Premature infants in neonatal intensive care units (NICUs) are highly susceptible to infection due to the immaturity of their immune systems, and nosocomial infections are a significant risk factor for death and poor neurodevelopmental outcome in this population. To investigate the impact of cleaning within a NICU, a high-throughput short-amplicon-sequencing approach was used to profile bacterial and fungal surface communities before and after cleaning. Intensive cleaning of surfaces in contact with neonates decreased the total bacterial load and the percentage of Streptococcus species with similar trends for total fungal load and Staphylococcus species; this may have clinical relevance since staphylococci and streptococci are the most common causes of nosocomial NICU infections. Surfaces generally had low levels of other taxa containing species that commonly cause nosocomial infections (e.g., Enterobacteriaceae) that were not significantly altered with cleaning. Several opportunistic yeasts were detected in the NICU environment, demonstrating that these NICU surfaces represent a potential vector for spreading fungal pathogens. These results underline the importance of routine cleaning as a means of managing the microbial ecosystem of NICUs and of future opportunities to minimize exposures of vulnerable neonates to potential pathogens and to use amplicon-sequencing tools for microbial surveillance and hygienic testing in hospital environments.
PMCID: PMC3719657  PMID: 23740726
16.  Multiresistant coagulase-negative staphylococci disseminate frequently between intubated patients in a multidisciplinary intensive care unit 
Critical Care  2003;8(1):R42-R47.
The intensive care unit is burdened with a high frequency of nosocomial infections often caused by multiresistant nosocomial pathogens. Coagulase-negative staphylococci (CoNS) are reported to be the third causative agent of nosocomial infections and the most frequent cause of nosocomial bloodstream infections. CoNS are a part of the normal microflora of skin but can also colonize the nasal mucosa, the lower airways and invasive devices. The main aim of the present study was to investigate colonization and the rate of cross-transmissions of CoNS between intubated patients in a multidisciplinary intensive care unit.
Materials and methods
Twenty consecutive patients, ventilated for at least 3 days, were included. Samples were collected from the upper and lower airways. All samples were cultured quantitatively and CoNS were identified by morphology and biochemical tests. A total of 199 CoNS isolates from 17 patients were genetically fingerprinted by pulsed-field gel electrophoresis in order to identify clones and to monitor dissemination within and between patients.
An unexpected high number of transmission events were detected. Five genotypes were each isolated from two or more patients, and 14/20 patients were involved in at least one and up to eight probable transmission events.
A frequent transmission of CoNS was found between patients in the intensive care unit. Although transmission of bacteria does not necessarily lead to infection, it is nevertheless an indication that infection control measures can be improved.
PMCID: PMC420068  PMID: 14975054
coagulase-negative staphylococci; colonization; cross-transmission; infection control measures; intensive care unit
17.  Neonatal Sepsis due to Coagulase-Negative Staphylococci 
Neonates, especially those born prematurely, are at high risk of morbidity and mortality from sepsis. Multiple factors, including prematurity, invasive life-saving medical interventions, and immaturity of the innate immune system, put these infants at greater risk of developing infection. Although advanced neonatal care enables us to save even the most preterm neonates, the very interventions sustaining those who are hospitalized concurrently expose them to serious infections due to common nosocomial pathogens, particularly coagulase-negative staphylococci bacteria (CoNS). Moreover, the health burden from infection in these infants remains unacceptably high despite continuing efforts. In this paper, we review the epidemiology, immunological risk factors, diagnosis, prevention, treatment, and outcomes of neonatal infection due to the predominant neonatal pathogen CoNS.
PMCID: PMC3674645  PMID: 23762094
18.  Nonperinatal Nosocomial Transmission of Candida albicans in a Neonatal Intensive Care Unit: Prospective Study 
Journal of Clinical Microbiology  1998;36(5):1255-1259.
Nosocomial Candida albicans infections have become a major cause of morbidity and mortality in neonates in neonatal intensive care units (NICUs). To determine the possible modes of acquisition of C. albicans in hospitalized neonates, we conducted a prospective study at Grady Memorial Hospital, Atlanta, Ga. Clinical samples for fungal surveillance cultures were obtained at birth from infants (mouth, umbilicus, and groin) and their mothers (mouth and vagina) and were obtained from infants weekly until they were discharged. All infants were culture negative for C. albicans at birth. Six infants acquired C. albicans during their NICU stay. Thirty-four (53%) of 64 mothers were C. albicans positive (positive at the mouth, n = 26; positive at the vagina, n = 18; positive at both sites, n = 10) at the time of the infant’s delivery. A total of 49 C. albicans isolates were analyzed by restriction endonuclease analysis and restriction fragment length polymorphism analysis by using genomic blots hybridized with the CARE-2 probe. Of the mothers positive for C. albicans, 3 of 10 were colonized with identical strains at two different body sites, whereas 7 of 10 harbored nonidentical strains at the two different body sites. Four of six infants who acquired C. albicans colonization in the NICU had C. albicans-positive mothers; specimens from all mother-infant pairs had different restriction endonuclease and CARE-2 hybridization profiles. One C. albicans-colonized infant developed candidemia; the colonizing and infecting strains had identical banding patterns. Our study indicates that nonperinatal nosocomial transmission of C. albicans is the predominant mode of acquisition by neonates in NICUs at this hospital; mothers may be colonized with multiple strains of C. albicans simultaneously; colonizing C. albicans strains can cause invasive disease in neonates; and molecular biology-based techniques are necessary to determine the epidemiologic relatedness of maternal and infant C. albicans isolates and to facilitate determination of the mode of transmission.
PMCID: PMC104810  PMID: 9574687
19.  Urinary tract infection concordance with positive blood and cerebrospinal fluid cultures in the neonatal intensive care unit 
Urinary tract infections (UTI) are common in the neonatal intensive care unit (NICU). Blood, urine, and cerebrospinal fluid (CSF) cultures are frequently obtained to evaluate for infection. We sought to determine the concordance between positive urine cultures and blood or CSF cultures.
Study design
Infants <121 days of age with a UTI admitted to 322 NICUs managed by the Pediatrix Medical Group from 1997–2010 were identified. UTIs were defined by isolation of a single pathogenic organism in a urine sample obtained by catheterization or suprapubic tap. The UTI was concordant if the same organism was identified in the blood or CSF within 3 days of the urine culture.
Of 5681 infants with a urine culture, 984 had 1162 UTIs. Nine hundred seventy-six UTIs (84%) had a blood culture collected within 3 days, and 127 (13%) were concordant. Of the 1162 UTIs, 77 (7%) had a CSF culture collected within 3 days, and 2 (3%) were concordant.
Collection of a urine culture in infants evaluated for late-onset sepsis is important. Concordance was observed in 13% of blood cultures and 3% of CSF cultures. These findings may be related to the initiation of empirical antimicrobial therapy before evaluation for disseminated infection or poor blood culture sensitivity.
PMCID: PMC3549035  PMID: 22935772
infant; sepsis
20.  Delta-like toxin produced by coagulase-negative staphylococci is associated with neonatal necrotizing enterocolitis. 
Infection and Immunity  1987;55(9):2268-2273.
Necrotizing enterocolitis (NEC) is a serious neonatal disorder of uncertain cause, although fecal bacteria have been implicated in some outbreaks. We examined coagulase-negative staphylococci (CONS) as possible etiologic agents. In our unit, CONS colonized the bowels of most infants studied, including 46% of 70 NEC cases (mean concentration, 10(9.1) CFU/g of stool). Over 90% of tested isolates produced a hemolysin resembling delta toxin of Staphylococcus aureus. Toxin purified from a NEC-associated isolate of Staphylococcus epidermidis resembled reference delta toxin from S. aureus in size, biologic properties, and antigenicity. This delta-like toxin was enteropathic, causing mucosal necrosis and hemorrhage in injected loops of the bowels of infant rats. Adjacent, nonexposed bowel remained normal, as did loops injected with lecithin-neutralized toxin. Using a new enzyme-linked immunosorbent assay (ELISA), we detected delta-like toxin in the stools of 11 of 35 infants colonized with CONS positive for delta-like toxin (Tox+). Positive tests were strongly associated with NEC. Of 18 cases with Tox+ CONS, 10 were positive (56%), whereas only 1 of 17 control infants so colonized was positive (6%, P = 0.002). In NEC patients, the mean fecal toxin concentration was 1,012 ng/g. Toxicity to fibroblasts was demonstrable in filtrates of each of six ELISA-positive samples tested but was absent in all five ELISA-negative samples tested. We conclude that delta-like toxin is elaborated in the bowels of some infants with Tox+ CONS, and its association with NEC suggests that such CONS are enteropathic. In our unit, this mechanism was apparent in 23% of 44 recent cases of endemic NEC.
PMCID: PMC260689  PMID: 3623702
21.  Susceptibility of bacterial etiological agents to commonly-used antimicrobial agents in children with sepsis at the Tamale Teaching Hospital 
Bloodstream infections in neonates and infants are life-threatening emergencies. Identification of the common bacteria causing such infections and their susceptibility patterns will provide necessary information for timely intervention. This study is aimed at determining the susceptibilities of bacterial etiological agents to commonly-used antimicrobial agents for empirical treatment of suspected bacterial septicaemia in children.
This is a hospital based retrospective analysis of blood cultures from infants to children up to 14 years of age with preliminary diagnosis of sepsis and admitted to the Neonatal Intensive Care Unit (NICU) and Paediatric Wards of the Teaching Hospital Tamale from July 2011 to January 2012.
Out of 331 blood specimens cultured, the prevalence of confirmed bacterial sepsis was 25.9% (86/331). Point prevalence for confirmed cases from NICU was 44.4% (28/63) and 21.6% (58/268) from the Paediatric ward. Gram positive cocci (GPC) were the predominant isolates with Coagulase positive (32.2%) and Coagulase-negative (28.7%) Staphylococci accounting for 60.9% of the total isolates. Gram negative rods (GNR) comprised 39.1% of all isolates with Klebsiella, E.coli and Salmonella being the most common organisms isolated. Klebsiella was the most frequent GNR from the NICU and Salmonella typhi was predominantly isolated from the paediatric ward. Acinetobacter showed 100.0% susceptibility to Ceftriaxone and Cefotaxime but was resistant (100.0%) to Ampicillin, Tetracycline and Cotrimoxazole. Escherichia coli and Klebsiella were 80.0% and 91.0% susceptible to Ceftriaxone and Cefotaxime respectively. Klebsiella species showed 8.3% susceptibility to Tetracycline but was resistant to Ampicillin and Cotrimoxazole. Escherichia coli showed 40.0% susceptibility to Ampicillin, Chloramphenicol and Cotrimoxazole; 20.0% susceptibility to Tetracycline and 80.0% susceptible to Gentamicin and Cefuroxime. Coagulase negative Staphylococci was susceptible to Gentamicin (72.0%) but Coagulase positive Staphylococci showed intermediate sensitivity to Gentamicin (42.9%).
Coagulase Negative, Coagulase Positive Staphylococci, Salmonella and Klebsiella were the aetiological agents of bloodstream infection among children at TTH. While gram-positive and gram-negative bacteria showed low susceptibility to Ampicillin, Tetracycline and Cotrimoxazole, the GNR were susceptible to Gentamicin and third-generation cephalosporins.
PMCID: PMC3598494  PMID: 23419199
22.  Etiology of Neonatal Blood Stream Infections in Tbilisi, Republic of Georgia 
Neonatal blood stream infections (BSI) are major cause of morbidity and mortality in developing countries. It is crucial to continuously monitor the local epidemiology of neonatal BSI to detect any changes in patterns of infection and susceptibility to various antibiotics.
To examine the etiology of BSI in two neonatal intensive care units (NICU) in the Republic of Georgia, a resource-poor country, and to determine antibiotic susceptibility of the isolated organisms.
Cross-sectional study among all septic infants was conducted in NICU of two pediatric hospitals in Tbilisi between 09/2003-09/2004.
A total of 200 infants with clinical signs of sepsis were admitted in two NICUs. Of these, 126 (63%) had confirmed bacteremia. Mortality rate was 34%. A total of 98 (78%) of 126 recovered isolates were Gram-negative organisms, and 28 (22%) were Gram-positive. Klebsiella pneumoniae was the most common pathogen, accounting for 36 (29%) of 126 isolates, followed by Enterobacter cloacae – 19 (15%), and S. aureus – 15 (12%). The gram-negative organisms showed high degree of resistance to commonly used antibiotics such as ampicillin, amoxicillin/clavulanate, and comparatively low resistance to amikacin, ciprofloxacin, carbapenems, and gentamicin; 40% of S. aureus isolates were methicillin resistant (MRSA). In multivariate analysis only umbilical discharge was a significant risk factor for having positive blood culture at admission to NICU (PR=2.25, 95% CI 1.82-2.77).
Neonatal BSI was mainly caused by gram-negative organisms, which are developing resistance to commonly used antibiotics. Understanding the local epidemiology of neonatal BSI can lead to the development of better medical practices, especially more appropriate choices for empiric antibiotic therapy, and may contribute to improvement of infection control practices.
PMCID: PMC2695829  PMID: 19058989
blood stream infections; Republic of Georgia; neonatal
23.  Early and Late Onset Sepsis in Very-Low-Birth-Weight Infants from a Large Group of Neonatal Intensive Care Units 
Early human development  2012;88(Suppl 2):S69-S74.
Very-low-birth-weight (VLBW, <1500 g birth weight) infants are at high risk for both early- and late-onset sepsis. Prior studies have observed a predominance of gram-negative organisms as a cause of early-onset sepsis and gram-positive organisms as a cause of late-onset sepsis. These reports are limited to large, academic neonatal intensive care units (NICUs) and may not reflect findings in other units. The purpose of this study was to determine the risk factors for sepsis, the causative organisms, and mortality following infection in a large and diverse sample of NICUs.
We analyzed the results of all cultures obtained from VLBW infants admitted to 313 NICUs from 1997 to 2010.
Over 108,000 VLBW infants were admitted during the study period. Early-onset sepsis occurred in 1032 infants, and late-onset sepsis occurred in 12,204 infants. Gram-negative organisms were the most commonly isolated pathogens in early-onset sepsis, and gram-positive organisms were most commonly isolated in late-onset sepsis. Early- and late-onset sepsis were associated with increased risk of death controlling for other confounders (odds ratio 1.45 [95% confidence interval 1.21, 1.73], and OR 1.30 [95% CI 1.21, 1.40], respectively).
This is the largest report of sepsis in VLBW infants to date. Incidence for early-onset sepsis and late-onset sepsis has changed little over this 14-year period, and overall mortality in VLBW infants with early- and late-onset sepsis is higher than in infants with negative cultures.
PMCID: PMC3513766  PMID: 22633519
early-onset sepsis; late-onset sepsis; very-low-birth-weight infants
24.  Epidemiology and Diagnosis of Hospital-Acquired Conjunctivitis Among Neonatal Intensive Care Unit Patients 
Few recent reports describe the epidemiology and risk factors for health care-associated conjunctivitis among neonatal intensive care unit (NICU) patients in developed countries. Reporting may be inaccurate in this population given that the National Nosocomial Infection Surveillance System (NNIS) definition is largely dependent on a positive culture, whereas clinical practice often consists of empiric treatment.
We describe the epidemiology of conjunctivitis among neonates in 2 level III–IV NICUs and compare the NNIS definition with our study definition: eye drainage and empiric treatment with or without a culture.
Patient demographics, clinical, device usage and conjunctivitis data collected prospectively from March 2001 through January 2003 were analyzed.
Conjunctivitis occurred in 5% (n = 154/2935) of infants, of whom 51% (n =79) were in NICU 1 and 49% (n =75) in NICU 2. Predominant pathogens included coagulase-negative staphylococci (25%), Staphylococcus aureus (19%) and Klebsiella spp. (10%). Significant predictors of conjunctivitis included low birth weight, use of ventilator or nasal cannula continuous positive airway pressure and study year. Ophthalmologic examination was an additional predictor of infection in NICU 1. Eye examination data were unavailable for NICU 2. Only 62% of cases that met the study definition for conjunctivitis met the NNIS definition, because many infants received empiric treatment.
Clinical conjunctivitis was associated with low birth weight and patient care factors that could lead to contamination of the eye with respiratory tract secretions. The NNIS definition failed to detect 38% of clinical infections. Consideration should be given to revising the definition of conjunctivitis for the NICU population.
PMCID: PMC2045635  PMID: 15998997
conjunctivitis; neonatal intensive care unit; low birth weight; premature infants
25.  Epidemiological and bacteriological investigation of Serratia marcescens epidemic in a nursery and in a neonatal intensive care unit. 
The Journal of Hygiene  1984;93(1):67-78.
An epidemic caused by Serratia marcescens that involved 26 infants admitted to the Neonatal Intensive Care Unit (NICU) and 82 infants admitted to the Nursery of the 2nd Medical School of Naples is reported. Two different biotypes of S. marcescens with two completely different epidemiological patterns were identified. The prevalent biotype (A8b trigonelline-) was isolated in the delivery room, in the operating room, in the Nursery and in the NICU from items, healthy infant excreters and affected infants; the second biotype (A3a) was isolated only in the NICU from staff, two healthy infant excreters and two affected infants. Colonization of the throat and the gastrointestinal tract was frequent. Infected and colonized infants were the most important reservoir for serratia in the Nursery and in the NICU particularly for the type strain A3a. A mucus aspiration apparatus contaminated in the delivery room and the contamination of several instruments and items probably had a major role in the initiation and maintenance of the spread of the A8b strain. Mass contamination of the nursery has been related to overcrowding and a lack of the control measures; the transfer of high-risk colonized infants caused spread in the NICU. In the NICU the attack rate 26%; 69% of infants became ill; the case fatality ratio was 19%. Epidemiological investigation of the infants at risk showed some factors predisposing to infection with serratia. The hygienic measures failed to control the spread of serratia and it was necessary to refuse new admissions to pregnant women in order to decontaminate and re-organize the wards.
PMCID: PMC2129282  PMID: 6379044

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