Emergence Of Coagulase-negative Staphylococci Research Articles

Common Bacterial Isolates Associated With Neonatal Sepsis and Their Antimicrobial Profile: A Retrospective Study at King Abdulaziz University Hospital, Jeddah, Saudi Arabia.

BackgroundNeonatal sepsis is a major contributor to morbidity and mortality among neonates. There has been considerable geographic variation in causative pathogens and antimicrobial sensitivity profiles over time. This makes the continuous monitoring of patterns of emergence crucial for the effective implementation of antimicrobial therapy guidelines in an attempt to control antimicrobial resistance.MethodsA retrospective study was conducted among neonates with sepsis admitted to King Abdulaziz University Hospital, Jeddah, Saudi Arabia, between May 2011 and October 2018. The data were collected from medical records in the neonatal intensive care unit and analyzed using SPSS version 20 (IBM Corp., Armonk, NY).ResultsThere were 246 neonates clinically diagnosed with sepsis, of whom 40 (16.26%) had positive blood cultures. In the blood cultures, coagulase-negative Staphylococcus was the most prevalent microorganism (57.5%), followed by Klebsiella spp. (10%). Streptococcus agalactiae, Enterobacter cloacae, Escherichia coli, Acinetobacter baumanii, and Candida spp. each accounted for 5% of all isolates. Only single isolates of methicillin-resistant Staphylococcus aureus, Pseudomonas aeruginosa, and Bacillus spp. (2.5% each) were detected in this study. Most of the isolated microorganisms exhibited high sensitivity to ampicillin and gentamicin.ConclusionsThis study points to a likely emergence of coagulase-negative Staphylococci as the main cause of sepsis among neonates. Ampicillin and gentamicin are highly effective against the commonly isolated bacterial pathogens that cause neonatal sepsis.

Pathogenic bacteria and their antibiotic sensitivity in ophthalmia neonatorum.

CONTEXT:Emergence of coagulase-negative staphylococci as pathogens in ophthalmia neonatorum.AIMS:To analyze the bacteriological spectrum of ophthalmia neonatorum and its associated risk factors.SETTINGS AND DESIGN:Retrospective analysis in a tertiary care hospital in India.SUBJECTS AND METHODS:A retrospective review was performed in a tertiary care center in India on 139 neonates presenting with conjunctivitis over a period of 3 years. All the neonates presenting to the out-patient department, those admitted in the Neonatal Intensive care Unit and in-patient wards were included in our study. The neonates were clinically examined and followed-up by a single experienced ophthalmologist. Details including demographic data, age of the infant, type of delivery, investigations, and treatment outcomes were analyzed.STATISTICAL ANALYSIS USED:Frequency calculation using Microsoft Excel for windows 10.RESULTS:In the 92 samples with growth (66.2%), the most common organisms isolated were coagulase-negative Staphylococci (35.9%), Klebsiella pneumoniae (16.3%), and Acinetobacter species (16.3%). Others were Staphylococcus aureus (14.1%), Pseudomonas aeruginosa (8.7%), and Escherichia coli (8.7%). Ophthalmia neonatorum was significantly higher in preterm infants born out of lower-segment cesarean section and those requiring ventilatory support.CONCLUSIONS:Unlike gonococcus, which is implicated in ophthalmia neonatorum, our study shows varied microbiological spectrum and sensitivity patterns with coagulase-negative staphylococci as the key pathogen. The role of coagulase-negative staphylococci as a disease-causing pathogen becomes increasingly important with an imperative need for prudent use of common antibiotics in treating these pathogenic bacteria.

Prevalence and antibiotic susceptibility pattern of Coagulase Negative Staphylococcus (CoNS) in neonatal septicemia

Introduction: Neonatal septicemia is important cause of neonatal mortality and morbidity. Neonatal Coagulase negative staphylococci(CoNS) infections are rarely fatal, but they cause significant morbidity, especially among very low birth weight infants. Objectives of the study:1. To know the prevalence of CoNS in neonatal sepsis; 2 To determine the antibiotic susceptibility pattern of CoNS in neonatal sepsis. Materials and Methods: A prospective study was conducted on blood samples of suspected neonatal septicemia between July 2017 and December 2017 received at Department of Microbiology, SIMS, Shimoga. Under aseptic precautions samples were collected and inoculated into BHI broth and subcultures were performed on MacConkey agar and blood agar plates and growth was processed by standard bacteriological technique. Antibiotic susceptibility testing was performed by Kirby Bauer Disk Diffusion test. Results were interpreted as per CLSI guidelines. Results: Out of 156 samples 98 were culture positive and 58 were culture negative. Most common organism isolated was Coagulase negative staphylococci(CoNS) 48.97%(48/98),Klebsiella species21.4%(21/98),Staphylococcus aureus10.2%(10/98),Gram Negative non fermenters 9.1%(9/98),Escherichia coli 2.04%(2/98), Citrobacter spp 4.08%(4/98),Pseudomonas spp 1.02%(1/98),Enterococcus spp 1.02%(1/98),Streptococcus spp 1.02%(1/98),Candida spp 1.02%(1/98). Gram positive organisms were highly sensitive for Linezolid, Vancomycin moderately sensitive for Gentamicin, Cotrimoxazole, ciprofloxacin and least sensitive for Erythromycin, Clindamycin, ciprofloxacin, Azithromycin, Cefoxitin(MRCoNS) Conclusion: This study showed emergence of Coagulase negative staphylococci(CoNS) as the most common pathogen in neonatal septicemia. Prevalence of MRCoNS and multidrug resistance among Coagulase negative staphylococci(CoNS) is seen. Keywords:Coagulase negative staphylococci, Neonatal septicemia, MRCoNS, Antibiotic susceptibility

Mannitol Fermenting Methicillin-Resistant Coagulase Negative Staphylococci Isolated From Diabetic Foot Infections

Detection of mannitol fermenting coagulase-negative staphylococci is frequently unnoticed when Staphylococcus aureus is screening in the laboratory. On the other hand, the emergence of coagulase-negative staphylococci as critical human pathogens need dependable methods for the identification of clinically significant coagulase-negative staphylococci to understand the epidemiology of infections caused by these bacteria. The study aimed to identify mannitol fermenting coagulase-negative staphylococci that assumed to be Staphylococcus aureus as they formed yellow colonies on Mannitol Salt agar plates. Samples were taken from eighty-four patients with diabetic foot infections. The specimen was cultured on Blood agar and Mannitol Salt agar. Mannitol fermenting coagulase-negative staphylococci isolates diagnosed through Vitek2 system then confirmed by detecting 16S rRNA gene and absence of the nuc gene. Antibiotic sensitivity and methicillin resistance were detected by Vitek2 system, then methicillin resistance was confirmed by Oxacillin Salt Agar Screen test and detection of the mecA gene. Out of 81 Staphylococcus isolated from foot and nose of diabetic foot patients, twenty isolates were mannitol fermenting coagulase-negative staphylococci, they related to following species; Staphylococcus haemolyticus, staphylococcus lentus, Staphylococcus xylosus, Staphylococcus lugdunensis, Staphylococcus hominis, Staphylococcus galinarum and Staphylococcus saprophyticus). The majority of them (85%) were phenotypically methicillin-resistant and genotypically harbouring mecA gene. 80% were resistant to Erythromycin, 70% to Clindamycin, 35% to Trimethoprim-Sulphamethoxazole, 30% to Gentamicin and Rifampicin, 15% to Levofloxacin and Teicoplanin. 30% expressed inducible clindamycin resistance.

Population Pharmacokinetics of Intravenous Linezolid in Premature Infants.

The emergence of coagulase-negative staphylococci with reduced vancomycin susceptibility in some neonatal intensive care units has resulted in an increase of linezolid use. Linezolid pharmacokinetics (PK) and safety in premature infants still need to be better established. This was a retrospective PK study. All infants who received intravenous linezolid and had linezolid plasma concentrations per standard of care were included. Linezolid concentrations were measured by high performance liquid chromatography. A population PK model was developed using nonlinear mixed effects modeling. Optimal dosing was determined based on achievement of the surrogate pharmacodynamics target for efficacy: a ratio of the area under the concentration-time curve to minimum inhibitory concentration >80. We assessed the occurrence of thrombocytopenia and lactic acidosis in relation with drug exposure. A total of 78 plasma concentrations were collected from 26 infants, with a median postnatal age (PNA) of 24 days (8-88) and weight of 1423 g (810-3256). A 1-compartment model described linezolid data well. The final model included PNA and weight on clearance and weight on volume of distribution. Considering an MIC90 of 1 mg/L, all infants reached an area under the concentration-time curve/minimum inhibitory concentration > 80. Although thrombocytopenia and hyperlactatemia occurred frequently, they were not sustained and were not considered related to linezolid. and was well tolerated in critically ill premature infants. PNA was the main determinant of clearance.

Emergence of Coagulase-Negative Staphylococci as a Cause of Native Valve Endocarditis

Coagulase-negative staphylococci (CoNS) are an infrequent cause of native valve endocarditis (NVE), and our understanding of NVE caused by CoNS is incomplete. The International Collaboration on Endocarditis-Prospective Cohort Study includes patients with endocarditis from 61 centers in 28 countries. Patients with definite cases of NVE caused by CoNS who were enrolled during the period June 2000-August 2006 were compared with patients with definite cases of NVE caused by Staphylococcus aureus and patients with NVE caused by viridans group streptococci. Multivariable logistic regression was used to determine factors associated with death in patients with NVE caused by CoNS. Of 1635 patients with definite NVE and no history of injection drug use, 128 (7.8%) had NVE due to CoNS. Health care-associated infection occurred in 63 patients (49%) with NVE caused by CoNS. Comorbidities, long-term intravascular catheter use, and history of recent invasive procedures were similar among patients with NVE caused by CoNS and among patients with NVE caused by S. aureus. Surgical treatment for endocarditis occurred more frequently in patients with NVE due to CoNS (76 patients [60%]) than in patients with NVE due to S. aureus (150 [33%]; P=.01) or in patients with NVE due to viridans group streptococci (149 [44%]; P=.01). Despite the high rate of surgical procedures among patients with NVE due to CoNS, the mortality rates among patients with NVE due to CoNS and among patients with NVE due to S. aureus were similar (32 patients [25%] and 124 patients [27%], respectively; P=.44); the mortality rate among patients with NVE due to CoNS was higher than that among patients with NVE due to viridans group streptococci (24 [7.0%]; P=.01). Persistent bacteremia (odds ratio, 2.65; 95% confidence interval, 1.08-6.51), congestive heart failure (odds ratio, 3.35; 95% confidence interval, 1.57-7.12), and chronic illness (odds ratio, 2.86; 95% confidence interval, 1.34-6.06) were independently associated with death in patients with NVE due to CoNS (c index, 0.73). CoNS have emerged as an important cause of NVE in both community and health care settings. Despite high rates of surgical therapy, NVE caused by CoNS is associated with poor outcomes.

Changing trend of neonatal infection: Experience at a newly established regional medical center in Korea

The purpose of the present paper was to study the natural history of neonatal sepsis in a newly established neonatal intensive care center that started in 1988 at Gyeongsang National University Hospital 9 (GNUH) in Chinju city, Korea. Neonates admitted to GNUH neonatal intensive care unit (NICU) between January 1988 and December 1997 were included. All organisms detected on blood and cerebrospinal fluid cultures were recorded. Neonatal sepsis was defined as 'clinical signs suggestive of sepsis with a positive blood and/or cerebrospinal fluid culture during the neonatal period'. Temporal trends and the distribution of pathogens in identified septic patients during the aforementioned period were studied descriptively. Between January 1988 and 31 December 1997, 3327 neonates were admitted to the center. A total of 6.7% of neonates (224/3327) had at least one positive blood culture. The vast majority (62%) of septic cases were caused by Gram-positive organisms. Coagulase-negative staphylococci (CONS) were the most common pathogens (24% of all infections, 38% of Gram-positive infections). The pathogen associated with the highest mortality was Klebsiella pneumoniae (25%, 10/39). Sepsis as a result of Gram-negative pathogens (especially K. pneumoniae) were involved in outbreaks that occurred for a few years during the study interval. The major outcome of this review was the emergence of CONS in the NICU during a relatively short period of time (10 years) as a common neonatal pathogen. This observation is similar to the experience of other centers over the last two decades.

Identification and molecular characterization of mannitol salt positive, coagulase-negative staphylococci from nasal samples of medical personnel and students

The identification of mannitol salt positive, coagulase-negative staphylococci (CNS) is often disregarded when Staphylococcus aureus is screened in clinical samples using mannitol salt agar. However, the emergence of CNS as important human pathogens has indicated that reliable methods for the identification of clinically significant CNS are of great importance in understanding the epidemiology of infections caused by them. The identification and molecular characterization of mannitol salt positive CNS from nasal samples of medical personnel and students is reported here. A total of 84 mannitol salt positive staphylococcal isolates were obtained from 240 nasal samples, of which 15 were CNS. The API STAPH system classified the CNS isolates into six species, and one-third of the isolates were identified with confidence levels of <80 %. 16S-23S rRNA intergenic spacer length polymorphism analysis (ITS-PCR) identified only two species (Staphylococcus haemolyticus and Staphylococcus saprophyticus). This identification was confirmed by antibiotyping, species-specific PCR and PFGE. The results from this study indicate that ITS-PCR is a potentially useful and reliable tool, enabling hospital laboratories to obtain rapid, full and accurate identification of CNS at the species level.

Emergence of coagulase negative staphylococci as major nosocomial bloodstream pathogens.

Over an eight year period, 1975 to 1982, 1,843 nosocomial bloodstream infections were identified by routine prospective surveillance at the University of Virginia Hospital (106/10,000 admissions). Despite a decline in overall bloodstream infection rates during the study period (P = .085), bloodstream infections due to gram positive organisms increased from 29 (1975-1978) to 43/10,000 (1979-1982), (P less than 0.001). Notably, rates for coagulase negative staphylococci increased from 5.2 (1975-1978) to 12.4/10,000 (1979-1982), (P less than 0.001). In 1982, coagulase negative staphylococci accounted for 17% of all bloodstream infections and were the most frequently isolated pathogens. Sixty-four percent of patients with coagulase negative staphylococci were in critical care units versus 41% with other bloodstream infections (P less than .05). The recognition of coagulase negative staphylococci as significant bloodstream pathogens markedly alters the clinician's approach to nosocomial septicemia.

New aspects of staphylococcal infections: emergence of coagulase-negative staphylococci as pathogens.

In contrast to the well-established pathogen Staphylococcus aureus, the coagulase-negative staphylococci, formerly collectively called S. epidermidis, were until recently regarded as harmless commensals. During the last two decades, however, the coagulase-negative staphylococci have clearly emerged as pathogens in patients carrying artificial devices, such as prosthetic heart valves, hip prostheses and cerebrospinal fluid shunts, and in patients with compromised host defenses such as premature neonates and cancer and transplant patients. The present paper reviews current insights on classification, bacteriology, pathogenic potential and virulence factors of coagulase-negative staphylococci. In addition, the role of host defense factors in resistance to staphylococcal infection is summarized as well as the main features of the clinical syndromes in which coagulase-negative staphylococci are involved.