Coagulase-negative staphylococci isolates from blood cultures of newborns in a tertiary hospital in southern Brazil

Abstract Neonatal sepsis continues to be a major cause of morbidity and mortality worldwide. Coagulase-negative staphylococci (CoNS), commonly found on the skin, being the main agents isolated. The aim of this study was to evaluate CoNS isolated from blood cultures of newborn (NB) infants. The study took place between 2014 and 2016/2017 in a tertiary hospital in southern Brazil. Using the VITEK 2 system (bioMérieux, Marcy l'Etoile, France), the microorganisms were identified and had their sensitivity profiles determined. The minimum inhibitory concentrations of linezolid, tigecycline, and vancomycin were also determined. The clinical parameters and mortality rates of NBs were evaluated. From January to December 2014, 176 CoNS isolates were obtained from 131 patients and from June 2016 to July 2017, 120 CoNS isolates were obtained from 79 patients. Staphylococcus epidermidis was most prevalent in both periods. Resistance rates increased between 2014 and 2016/2017, especially against ciprofloxacin (52.27% and 73.11%, p = 0.0004), erythromycin (51.40% and 68.07%, p = 0.0054), gentamicin (50.59% and 67.23%, p = 0.0052), and penicillin (71.3% and 99.17%, p = 0.0001), respectively. With 100% susceptibility to linezolid, tigecycline, and vancomycin in both periods and methodologies tested. In 2014, 53.44% of the NBs received antibiotic therapy, and of these, 77.14% used a catheter; in 2016/2017, these were 78.48% and 95.16%, respectively. Regarding laboratory tests, a hemogram was ineffective, since patients with sepsis presented normal reference values. In 2014 and 2016/17, 15.71% and 17.74% of the NBs died, respectively. S. epidermidis was the predominant microorganism, related to catheter use in most cases. The resistance rates have increased over time, demonstrating the importance of adopting control and prevention measures in this hospital. CoNS are responsible for a significant neonatal sepsis mortality rate in infants.

Simple indictor of increased blood culture contamination rate by detection of coagulase-negative staphylococci.

Coagulase-negative staphylococci (CoNS) are the most frequent contaminating bacteria; therefore, we aimed to investigate an indicator of CoNS to predict the increase in blood culture contamination rate (ConR). We performed a retrospective study of selected patients, who underwent blood culture testing. Contamination was defined as the presence of either one of two or more sets of skin-resident bacteria, except for cases with a low likelihood of contamination based on clinical aspects. We calculated the monthly ConR [(total number of contaminated cases per month)/(total number of blood culture sets collected per month) × 100] and analysed the ConR prediction ability using the following four indicators: the number of CoNS-positive sets of blood cultures, cases with at least one CoNS-positive blood culture set, cases with only one CoNS-positive blood culture set, and cases of contamination by CoNS. Cases with CoNS-positive blood cultures correlated with ConR (r = 0.85). Although the area under the receiver operating characteristic curve for the number of cases with ConR ≥ 2.5 differed significantly from that of the number of cases contaminated by CoNS, the negative predictive value was high, reaching up to 95.5% (95% confidential interval 87.3-99.1). The number of CoNS-positive cases could help predict an increase in ConR ≥ 2.5.

Comparison of culture-negative and culture-positive sepsis or septic shock: a systematic review and meta-analysis.

BACKGROUND: Mortality and other clinical outcomes between culture-negative and culture-positive septic patients have been documented inconsistently and are very controversial. A systematic review and meta-analysis was performed to compare the clinical outcomes of culture-negative and culture-positive sepsis or septic shock. METHODS: We searched the PubMed, Cochrane and Embase databases for studies from inception to the 1st of January 2021. We included studies involving patients with sepsis or septic shock. All authors reported our primary outcome of all-cause mortality and clearly compared culture-negative versus culture-positive patients with clinically relevant secondary outcomes (ICU length of stay, hospital length of stay, mechanical ventilation requirements, mechanical ventilation duration and renal replacement requirements). Results were expressed as odds ratio (OR) and mean difference (MD) with accompanying 95% confidence interval (CI). RESULTS: Seven studies including 22,655 patients were included. The primary outcome of this meta-analysis showed that there was no statistically significant difference in the all-cause mortality between two groups (OR = 0.95; 95% CI, 0.88 to 1.01; P = 0.12; Chi-2 = 30.71; I2 = 80%). Secondary outcomes demonstrated that there was no statistically significant difference in the ICU length of stay (MD = - 0.19;95% CI, - 0.42 to 0.04; P = 0.10;Chi-2 = 5.73; I2 = 48%), mechanical ventilation requirements (OR = 1.02; 95% CI, 0.94 to 1.11; P = 0.61; Chi2 = 6.32; I2 = 53%) and renal replacement requirements (OR = 0.82; 95% CI, 0.67 to 1.01; P = 0.06; Chi-2 = 1.21; I2 = 0%) between two groups. The hospital length of stay of culture-positive group was longer than that of the culture-negative group (MD = - 3.48;95% CI, - 4.34 to - 2.63; P < 0.00001;Chi-2 = 1.03; I2 = 0%). The mechanical ventilation duration of culture-positive group was longer than that of the culture-negative group (MD = - 0.64;95% CI, - 0.88 to - 0.4; P < 0.00001;Chi-2 = 4.86; I2 = 38%). CONCLUSIONS: Culture positivity or negativity was not associated with mortality of sepsis or septic shock patients. Furthermore, culture-positive septic patients had similar ICU length of stay, mechanical ventilation requirements and renal replacement requirements as those culture-negative patients. The hospital length of stay and mechanical ventilation duration of culture-positive septic patients were both longer than that of the culture-negative patients. Further large-scale studies are still required to confirm these results.