Evaluation of Biofilm Formation and Prevalence of Multidrug-Resistant Strains of Staphylococcus epidermidis Isolated from Neonates with Sepsis in Southern Poland

Staphylococcus epidermidis strains play an important role in nosocomial infections, especially in the ones associated with biofilm formation on medical devices. The paper was aimed at analyzing the mechanisms of antibiotic resistance and confirming the biofilm-forming ability among S. epidermidis strains isolated from the blood of hospitalized newborns. Genetic analysis of resistance mechanism determinants included multiplex PCR detection of mecA, ermA, ermB, ermC, msrA, and mef genes. Biofilm analysis comprised phenotypic and genotypic methods including Christensen and Freeman methods and PCR detection of the icaADB gene complex. Among the tested S. epidermidis strains, 89% of the isolates were resistant to methicillin, 67%—to erythromycin, 53%—to clindamycin, 63%—to gentamicin, and 23%—to teicoplanin, while all the strains were susceptible to vancomycin and linezolid. The mecA gene was detected in 89% of the isolates, the ermC gene was the most common and present among 56% of the strains, while the msrA gene was observed in 11% isolates. Eighty-five percent of the strains were described as biofilm-positive by phenotypic methods and carried the icaADB gene cluster. Multidrug resistance and the biofilm-forming ability in most of the strains tested may contribute to antimicrobial therapy failure (p < 0.05).

Antimicrobial susceptibility and prevalence of extended-spectrum beta-lactamases in clinical strains of Klebsiella pneumoniae isolated from pediatric and adult patients of two Polish hospitals

Klebsiella pneumoniae due to the presence of multiple antibiotic resistance mechanisms is one of the most threatening human pathogens nowadays. The aim of the study was to characterize antimicrobial susceptibility, presence of resistance mechanisms and the prevalence of selected genes encoding ESBLs in 170 K. pneumoniae isolates recovered from children and adults hospitalized in two Polish medical centers from 2008 to 2015. The phenotypic identification of strains was confirmed by amplification of mdh gene. ESBLs, metallo-beta- lactamases, Klebsiella pneumoniae carbapenemases and OXA-48 were detected using phenotypic tests. The blaCTX-M-1, blaTEM and blaSHV ESBL genes were amplified by PCR. Pediatric K. pneumoniae isolates displayed significantly higher resistance to piperacillin/tazobactam, cefoxitin, imipenem, amikacin and ciprofloxacin than strains obtained from adults (P<0.05). The presence of ESBLs, OXA-48, KPC and MBL was confirmed in 80.6%, 21.8%, 8.2% and 2.4%, respectively, of the tested strains. The CTX-M-1 enzymes were predominant (91.2%), followed by TEM (63.5%) and SHV (11.8%). The blaTEM was significantly more common in adults than in children (P<0.05). Dual or triple bla genes were observed in 55.9% and 8.2% of K. pneumoniae isolates. Further local epidemiological studies are required to monitor the dissemination of multidrug-resistant K. pneumoniae strains.

KPC-2-producing Klebsiella pneumoniae ST11 in a Children's Hospital in Poland

Four Klebsiella pneumoniae isolates from children hospitalized over 10 months in an intensive care unit in a children's teaching hospital in Poland were analyzed. All of the isolates belonged to a single pulsotype and sequence type (ST) 11, and produced the KPC-2 carbapenemase and extended-spectrum β-lactamase (ESBL) CTX-M-15. They were resistant to a variety of antimicrobials, and their β-lactam resistance patterns were typical for KPC producers. This is one of few cases of identification of KPC (or carbapenemase)-producing K. pneumoniae in a pediatric center in Poland.

Clonal Structure and Characterization of Staphylococcus aureus Strains from Invasive Infections in Paediatric Patients from South Poland: Association between Age, spa Types, Clonal Complexes, and Genetic Markers

The aim of current study was to examine clonal structure and genetic profile of invasive Staphylococcus aureus isolates recovered from infants and children treated at the Jagiellonian University Children’s Hospital of Krakow, Poland. The 107 invasive S. aureus isolates, collected between February 2012 and August 2014, were analysed retrospectively. Antimicrobial susceptibility testing, spa typing and DNA microarray analysis were performed to determine clonal distribution, diversity and gene content in regard to patients characteristics. In total, 107 isolates were recovered from 88 patients with clinical symptoms of invasive bacterial infection. The final set of 92 non-duplicate samples included 38 MRSA isolates. Additionally, a set of 54 S. aureus isolates collected during epidemiological screening was genotyped and analysed. There were 72 healthcare-associated (HCA) and 20 community-onset (CO) infection events caused by 33 and 5 MRSA isolates, respectively. The majority of isolates were affiliated with the major European clonal complexes CC5 (t003, spa-CC 002), CC45 (spa-CC 015), CC7 or CC15 (t084, t091, spa-CC 084). Two epidemic clones (CC5-MRSA-II or CC45-MRSA-IV) dominated among MRSA isolates, while MSSA population contained 15 different CCs. The epidemiological screening isolates belonged to similar genetic lineages as those collected from invasive infection cases. The HCA infection events, spa types t003, t2642 or CC5 were significantly associated with infections occurring in neonates and children under 5 years of age. Moreover, carriage of several genetic markers, including erm(A), sea (N315), egc-cluster, chp was significantly higher in isolates obtained from children in this age group. The spa types t091 and t008 were underrepresented among patients aged 5 years or younger, whereas spa type t008, CC8 and presence of splE was associated with infection in children aged 10 years or older. The HCA-MRSA strains were most frequently found in children under 5 years, although the majority of invasive infections was associated with MSSA strains. Moreover, an association between age group of children from the study population and a specific strain genotype (spa type, clonal complex or genetic content) was observed among the patients.