Multi-resistant Staphylococcus haemolyticus in a neonatal unit in New Delhi

Emergence of multidrug-resistant Staphylococcus haemolyticus in neonatal intensive care unit in Southern France, a genomic study

An emergence of multidrug-resistant (MDR) Staphylococcus haemolyticus has been observed in the neonatal intensive care unit (NICU) of Nîmes University Hospital in southern France. A case-control analysis was conducted on 96 neonates, to identify risk factors associated with S. haemolyticus infection, focusing on clinical outcomes. Forty-eight MDR S. haemolyticus strains, isolated from neonates between October 2019 and July 2022, were investigated using routine in vitro procedures and whole-genome sequencing. Additionally, five S. haemolyticus isolates from adult patients were sequenced to identify clusters circulating within the hospital environment. The incidence of neonatal S. haemolyticus was significantly associated with low birth weight, lower gestational age, and central catheter use (p < 0.001). Sepsis was the most frequent clinical manifestation in this series (20/46, 43.5%) and was associated with five deaths. Based on whole-genome analysis, three S. haemolyticus genotypes were predicted: ST1 (6/53, 11%), ST25 (3/53, 5.7%), and ST29 (44/53, 83%), which included the subcluster II-A, predominantly emerging in the neonatal department. All strains were profiled in silico to be resistant to methicillin, erythromycin, aminoglycosides, and fluoroquinolones, consistent with in vitro antibiotic susceptibility tests. Moreover, in silico prediction of biofilm formation and virulence-encoding genes supported the association of ST29 with severe clinical outcomes, while the persistence in the NICU could be explained by the presence of antiseptic and heavy metal resistance-encoding genes. The clonality of S. haemolyticus ST29 subcluster II-A isolates confirms healthcare transmission causing severe infections. Based on these results, reinforced hygiene measures are necessary to eradicate the nosocomial transmission of MDR strains.

The Role of Coagulase-Negative Staphylococci Biofilms on Late-Onset Sepsis: Current Challenges and Emerging Diagnostics and Therapies

Infections are one of the most significant complications of neonates, especially those born preterm, with sepsis as one of the principal causes of mortality. Coagulase-negative staphylococci (CoNS), a group of staphylococcal species that naturally inhabit healthy human skin and mucosa, are the most common cause of late-onset sepsis, especially in preterms. One of the risk factors for the development of CoNS infections is the presence of implanted biomedical devices, which are frequently used for medications and/or nutrient delivery, as they serve as a scaffold for biofilm formation. The major concerns related to CoNS infections have to do with the increasing resistance to multiple antibiotics observed among this bacterial group and biofilm cells’ increased tolerance to antibiotics. As such, the treatment of CoNS biofilm-associated infections with antibiotics is increasingly challenging and considering that antibiotics remain the primary form of treatment, this issue will likely persist in upcoming years. For that reason, the development of innovative and efficient therapeutic measures is of utmost importance. This narrative review assesses the current challenges and emerging diagnostic tools and therapies for the treatment of CoNS biofilm-associated infections, with a special focus on late-onset sepsis.

Biofilm Formation by ica-Negative Ocular Isolates of Staphylococcus haemolyticus

Staphylococcus haemolyticus is the second most frequently isolated CoNS from ocular infections and human blood cultures. In this study, we examined 18 ocular S. haemolyticus isolates for their capacity to form biofilm and conducted detachment assay to determine the composition of the biofilm matrix and involvement of various elements in cell lysis. PCR identified the presence of biofilm-associated genes, and ica operon and CLSM visualized the components of the biofilm matrix. We found that PIA-independent biofilm formation is the characteristic feature of S. haemolyticus isolates, irrespective of the sources of isolation, and protein or DNA or both are the major components of the biofilm matrix. Cell lysis enabling DNA release was an essential step for biofilm attachment during the initial stages of biofilm development. The srtA transcript expression study indicates its role in the early stages of biofilm development. We found the presence of antibiotic resistance genes in the eDNA and gDNA thus suggesting the possible role of biofilm in horizontal gene transfer of antibiotic resistance determinants. The overall study indicates that S. haemolyticus formed the biofilm comprising of protein or DNA or both and srtA play a role in the initial development of biofilm.

Identification of Novel Sequence Types among Staphylococcus haemolyticus Isolated from Variety of Infections in India

The aim of this study was to determine sequence types of 34 S. haemolyticus strains isolated from a variety of infections between 2013 and 2016 in India by MLST. The MEGA5.2 software was used to align and compare the nucleotide sequences. The advanced cluster analysis was performed to define the clonal complexes. MLST analysis showed 24 new sequence types (ST) among S. haemolyticus isolates, irrespective of sources and place of isolation. The finding of this study allowed to set up an MLST database on the PubMLST.org website using BIGSdb software and made available at http://pubmlst.org/shaemolyticus/. The data of this study thus suggest that MLST can be used to study population structure and diversity among S. haemolyticus isolates.

Multidrug-resistant Staphylococcus haemolyticus isolates from infected eyes and healthy conjunctivae in India

This study aimed to determine the presence of antibiotic resistance genes (ARGs), SCCmec elements and genetic relatedness among Staphylococcus haemolyticus isolated from patients with a variety of eye infections (n=11) and from healthy conjunctiva (n=7). Minimum inhibitory concentrations were determined for 14 antimicrobials according to BSAC guidelines. PCR was used to identify the presence of mecA, mecC, SCCmec type and ARGs. Sequencing was used to determine mutations in gyrA, gyrB, topoisomerase IVA and IVB genes. Genetic relatedness was determined by PFGE. Of the 18 isolates, 17 showed resistance to at least one antibiotic, but none showed resistance to vancomycin or rifampicin. Ten isolates were oxacillin-resistant and carried the mecA gene, eight of which belonged to SCCmec type V. The presence of non-mec SCC elements in two meticillin-susceptible isolates and untypeable SCC elements in meticillin-resistant isolates suggests the involvement of S. haemolyticus in the diversification of SCC elements. Sequence analysis revealed point mutations in gyrA (Ser-84→Leu) and topoisomerase IVA genes (Ser-80→Leu) in 13 isolates, and additional variation in the QRDR (Asp-84→Asn) of two isolates, showing good correlation between mutations in gyrA and topoisomerase IV genes and the level of resistance to fluoroquinolones. PFGE analysis showed distinct pulsotypes forming two major clusters, indicating the existence of diversity among isolates, irrespective of the source of isolation. This study suggests that S. haemolyticus isolates from infected eyes and healthy conjunctivae invariably carried ARGs and SCCmec elements and showed diversity in their genomic content, irrespective of the source of isolation.

Antibiotics and Antifungals in Neonatal Intensive Care Units: A Review

The incidence of infections is higher in the neonatal period than at any time of life. The basic treatment of infants with infection has not changed substantially over the last years. Antibiotics (with or without supportive care) are one of the most valuable resources in managing sick newborn babies. Early-onset (ascending or transplacental) or late-onset (hospital acquired) infections present different chronology, epidemiology, physiology and outcome. Some classes of antibiotics are frequently used in the neonatal period: penicillins, cephalosporins, aminoglycosides, glycopeptides, monobactams, carbapenems. Other classes of antibiotics (chloramphenicol, cotrimoxazole, macrolides, clindamycin, rifampicin and metronidazole) are rarely used. Due to emergence of resistant bacterial strains in Neonatal Intensive Care Units (NICU), other classes of antibiotics such as quinolones and linezolid will probably increase their therapeutic role in the future. Although new formulations have been developed for treatment of fungal infections in infants, amphotericin B remains first-line treatment for systemic Candida infection. Prophylactic antibiotic therapy is almost always undesirable. Challenges from pathogens and antibiotic resistance in the NICU may warrant modification of traditional antibiotic regimens. Knowledge of local flora and practical application of different antibiotic characteristics are key to an effective and safe utilization of antibiotics and antifungals in critical newborns admitted to the NICU, and especially in very low birth weight infants.

Biofilm formation by Staphylococcus haemolyticus

Infections due to coagulase-negative staphylococci (CoNS) most frequently occur after the implantation of medical devices and are attributed to the biofilm-forming potential of CoNS. Staphylococcus haemolyticus is the second most frequently isolated CoNS from patients with hospital-acquired infections. There is only limited knowledge of the nature of S. haemolyticus biofilms. The aim of this study was to characterize S. haemolyticus biofilm formation. We analyzed the biofilm-forming capacities of 72 clinical S. haemolyticus isolates. A detachment assay with NaIO(4), proteinase K, or DNase was used to determine the main biofilm components. Biofilm-associated genes, including the ica operon, were analyzed by PCR, and the gene products were sequenced. Confocal laser scanning microscopy (CLSM) was used to elucidate the biofilm structure. Fifty-three isolates (74%) produced biofilms after growth in Trypticase soy broth (TSB) with glucose, but only 22 (31%) produced biofilms after growth in TSB with NaCl. It was necessary to dissolve the biofilm in ethanol-acetone to measure the optical density of the full biofilm mass. DNase, proteinase K, and NaIO(4) caused biofilm detachment for 100%, 98%, and 38% of the isolates, respectively. icaRADBC and polysaccharide intercellular adhesin (PIA) production were found in only two isolates. CLSM indicated that the biofilm structure of S. haemolyticus clearly differs from that of S. epidermidis. We conclude that biofilm formation is a common phenotype in clinical S. haemolyticus isolates. In contrast to S. epidermidis, proteins and extracellular DNA are of functional relevance for biofilm accumulation, whereas PIA plays only a minor role. The induction of biofilm formation and determination of the biofilm mass also needed to be optimized for S. haemolyticus.

A three-year surveillance of nosocomial infections by methicillin-resistant Staphylococcus haemolyticus in newborns reveals the disinfectant as a possible reservoir

OBJECTIVE

Study of the clonality of methicillin-resistant Staphylococcus haemolyticus responsible of epidemic infections in a neonatal intensive care unit.

PATIENTS AND METHODS

Methicillin-resistant Staphylococcus haemolyticus isolates were collected during the period from March 2004 to November 2006, from newborns, the clean hands of nurses and from disinfectant bottles used in the unit. Molecular typing by pulsed-field gel electrophoresis (PFGE) was achieved for all isolates.

RESULTS

Forty-six isolates of S. haemolyticus resistant to methicillin were collected from 42 newborns, the hand of two nurses and from two disinfectant bottles used in the unit. PFGE analysis revealed five types (A, B, C, D and E) among newborns isolates. Types A and B were predominant. Nurses' isolates revealed PFGE types similar to types A and B. Disinfectant isolates were of type B. qacA/B PCR analysis revealed that the majority of type B isolates contain the disinfectant resistance gene qacA/B. No isolate of type A possessed this gene.

CONCLUSION

These results suggest that MRSH neonatal infections are caused by a limited number of clones. Clone B was able to survive in disinfectant bottles and to conserve its ability to infect newborns. We therefore conclude that the disinfectant can serve as a reservoir for MRSH and point out the need to control all disinfectants used in a neonatal intensive care unit.

Isolation and molecular characterization of multiresistant Staphylococcus sciuri and Staphylococcus haemolyticus associated with skin and soft-tissue infections

The isolation, molecular identification and genotyping of multiresistant Staphylococcus sciuri and Staphylococcus haemolyticus from skin and soft-tissue infections are reported. Accurate and full identification of three coagulase-negative staphylococcal isolates was achieved using PCR, while the API STAPH method failed to identify an isolate of S. haemolyticus fully. The PCR assay, which detects polymorphism in the 16S-23S rRNA spacer region, is shown to be potentially useful for rapid and accurate identification of coagulase-negative staphylococci. Identical PFGE type and antibiotic-resistance profiles of two methicillin-resistant S. haemolyticus isolates in this study suggest the existence of a multiresistant community clone.

Social factors influencing the acquisition of antibiotics without prescription in Kerala State, south India

We investigated the magnitude of self-medication with antibiotics in a peri-urban area of Southern Kerala State, India and factors influencing this practice. First, a random sample of 400 households was surveyed in one primary health centre area near Trivandrum. We found 69.3% (95% CI = 64.8-73.8) of households had at least one person using a pharmaceutical product during the two-week recall period; antibiotics formed almost 11% of the medicines consumed. Next, pharmacy based interview and observation data were collected from 405 antibiotic purchasers sampled from 11 out of the 12 private pharmacies in the area. Seventy-three of these 405 customers purchased antibiotics without a prescription (18%; 95% CI = 14.3-21.7). By combining the household survey and pharmacy observations, we estimate that almost half of 1% (0.41%; 95% CI = 0.24-1.16) of the population, or four people per 1000, is engaged in self-medication using antibiotics in Kerala in any two-week period. Our data show that people least likely to follow this practice are from higher income families, having more education and higher status occupations and receiving the benefits of medical insurance. Conversely, logistic regression analysis indicated that risk of buying antibiotics without a script was associated with education at secondary level or below, the perception that it is expensive to consult a doctor and low satisfaction with medical practitioners. Keralites' self-medication patterns are interpreted broadly using social, cultural, historical and economic perspectives. Solutions to the problem of antibiotic misuse are suggested, proceeding on several fronts: among practitioners, suppliers and marketeers of medicines, and among the population of pharmaceutical consumers themselves.

Antibiotics in neonatal infections: a review

The bacteria most commonly responsible for early-onset (materno-fetal) infections in neonates are group B streptococci, enterococci, Enterobacteriaceae and Listeria monocytogenes. Coagulase-negative staphylococci, particularly Staphylococcus epidermidis, are the main pathogens in late-onset (nosocomial) infections, especially in high-risk patients such as those with very low birthweight, umbilical or central venous catheters or undergoing prolonged ventilation. The primary objective of the paediatrician is to identity all potential cases of bacterial disease quickly and begin antibacterial treatment immediately after the appropriate cultures have been obtained. Combination therapy is recommended for initial empirical treatment in the neonate. In early-onset infections, an effective first-line empirical therapy is ampicillin plus an aminoglycoside (duration of treatment 10 days). An alternative is ampicillin plus a third-generation cephalosporin such as cefotaxime, a combination particularly useful in neonatal meningitis (mean duration of treatment 14 to 21 days), in patients at risk of nephrotoxicity and/or when therapeutic monitoring of aminoglycosides is not possible. Another potential substitute for the aminoglycoside is aztreonam. Triple combination therapy (such as amoxicillin plus cefotaxime and an aminoglycoside) could also be used for the first 2 to 3 days of life, followed by dual therapy after the microbiological results. In late-onset infections the combination oxacillin plus an aminoglycoside is widely recommended. However, vancomycin plus ceftazidime (+/- an aminoglycoside for the first 2 to 3 days) may be a better choice. Teicoplanin may be a substitute for vancomycin. However, the initial approach should always be modified by knowledge of the local bacterial epidemiology. After the microbiological results, treatment should be switched to narrower spectrum agents if a specific organism has been identified, and should be discontinued if cultures are negative and the neonate is in good clinical condition. Penicillins and third-generation cephalosporins are generally well tolerated in neonates. There is controversy regarding whether therapeutic drug monitoring of aminoglycosides will decrease toxicity (particularly renal damage) in neonates, and on the efficacy and safety of a single daily dose versus multiple daily doses of these drugs. Toxic effects caused by vancomycin are uncommon, but debate still exists over the need for therapeutic drug monitoring of this agent. When antibacterials are used in neonates, accurate determination of dosage is required, particularly for compounds with a low therapeutic index and in patients with renal failure. Very low birthweight infants are also particularly prone to antibacterial-induced toxicity.

Molecular characterization of epidemic multiresistant Staphylococcus haemolyticus isolates

Fifty-five Staphylococcus haemolyticus specimens isolated from patients and neonatal intensive care unit staff were tested for susceptibility to 12 antimicrobial agents. There were 34 multidrug-resistant isolates which were resistant to oxacillin, ampicillin, cefazolin, cefmetazole, imipenem, and gentamicin. These isolates had a higher frequency of resistance to tobramicin and ofloxacin, and relatively high MICs (2 to 4 micrograms/mL) for vancomycin, although none of the isolates were vancomycin resistant. To investigate hospital-acquired colonization and infection by multiresistant S. haemolyticus, we examined all isolates by pulsed-field gel electrophoresis (PFGE) after SmaI and SstII digestion, and detected an endemic PFGE pattern in multiresistant isolates. The results suggested that local spread of multiresistant S. haemolyticus was hospital acquired, and that the hospital staffs functioned as a reservoir.