Prevalence and clinical relevance of colonization with methicillin-resistant Staphylococcus aureus in the obstetric population.

BACKGROUND AND AIMS: Routine screening for Methicillin-Resistant Staphylococcus aureus (MRSA) in pregnant women is common practice in many hospitals. However, little is known on its prevalence and clinical relevance in this population. In this prospective longitudinal study, we aimed to investigate the MRSA prevalence in our obstetric population, the rate of vertical transmission of MRSA and the potential clinical relevance of MRSA colonization for both mother and child. A possible correlation between GBS and MRSA colonization was also investigated. MATERIALS AND METHODS: MRSA screening samples were collected at 35-37 weeks of gestation (from mother), at delivery and at discharge (from mother and newborn). All samples were analyzed by conventional microbiological methods and MRSA strains were subjected to spa-typing to investigate genetic similarity. The medical records of all positive mother-child pairs were analyzed to detect the occurrence of clinical infection in the postpartum period. RESULTS: 679 mother-child pairs were included between June 2014 and July 2016. Maternal MRSA positivity rate was 1.3% at 35-37 weeks (vaginal/anorectal), 3.1% at delivery (nose/throat) and 3.6% at discharge (nose/throat). MRSA positivity in neonates was 0.3% at delivery and increased to 3% at discharge (nose/umbilicus). Almost all MRSA positive children were born to MRSA positive mothers (OR 120.40, 95% CI: 38.42-377.32). Genetic similarity of the MRSA strains found in mother and child was illustrated for all but one case. 57.7% of the cases of MRSA colonization in our cohort were associated with livestock exposure. 31% of the MRSA positive mothers developed an infectious complication in the postpartum period. No neonatal infectious complications were observed. GBS positivity was not a predictive factor for MRSA colonization in our cohort. CONCLUSION: The rate of MRSA colonization (overall 4.3%) in our obstetric population is similar to that described in the literature and that of the general population admitted to our hospital in the same period. Maternal MRSA colonization appeared to be an important risk factor for neonatal colonization. Whereas mothers were at higher risk of developing infectious morbidity in the postpartum period, no neonatal infectious complications were observed. We observed no correlation between GBS and MRSA colonization.

A case of a surgical-site infection with Staphylococcus condimenti.

INTRODUCTION: Coagulase-negative staphylococci (CNS) are considered to have a medium or low pathogenic capacity when compared to S. aureus. Among the more harmless, CNS are those that are used in the food industry, represented by S. carnosus, whose genome has extensively been studied. Its genome was found to contain several genomic sequences that have a virulent function in the pathogenic S. aureus. Even though these genes are probably not virulent in S. carnosus, their presence might indicate a more virulent potential. We report the third clinical case associated with a surgical-site infection with S. condimenti, which belongs to these food industry related CNS. It corresponds to a blood stream infection, secondary to a surgical-site infection. RESULTS: Antibiotic susceptibility testing indicated a resistance to erythromycin and rifampicin, which was partly confirmed by the presence of a macrolide resistance gene by PCR screening for S. aureus virulence factors. Although no other putative virulence factors were detected, this organism managed to cause a severe post-operative wound infection. CONCLUSION: This case shows that CNS that are currently used in the food industry may play a role in human infection. With technologies such as MALDI-TOF, pathogens that are regarded non-pathogenic could be identified more often. Therefore, the risk of different Staphylococcus strains used in the food industry must be better assessed.

An Outpatient Clinic as a Potential Site of Transmission for an Outbreak of New Delhi Metallo-ß-Lactamase-producing Klebsiella pneumoniae Sequence Type 716: A Study Using Whole-genome Sequencing.

BACKGROUND: The incidence of nosocomial infections due to carbapenem-resistant Klebsiella pneumoniae is increasing worldwide. Whole-genome sequencing (WGS) can help elucidate the transmission route of nosocomial pathogens. METHODS: We combined WGS and epidemiological data to analyze an outbreak of New Delhi metallo-ß-lactamase (NDM)-producing K. pneumoniae that occurred in 2 Belgian hospitals situated about 50 miles apart. We characterized 74 NDM-producing K. pneumoniae isolates (9 from hospital A, 24 from hospital B, and 41 contemporary isolates from 15 other Belgian hospitals) using pulsed-field gel electrophoresis and WGS. RESULTS: A K. pneumoniae sequence type 716 clone was identified as being responsible for the outbreak with all 9 strains from hospital A and 20 of 24 from hospital B sharing a unique pulsotype and being clustered together at WGS (compared with 1 of 41 isolates from other Belgian hospitals). We identified the outpatient clinic of hospital B as the probable bridging site between the hospitals after combining epidemiological, phylogenetic, and resistome data. We also identified the patient who probably caused the transmission. In fact, all but 1 strain from hospital A carried a Tn1331-like transposon, whereas none of the hospital B isolates did. The patient from hospital A who did not have the Tn1331-like transposon was treated at the outpatient clinic of hospital B on the same day as the first NDM-producing K. pneumoniae-positive patient from hospital B. CONCLUSIONS: The results from our WGS-guided investigation highlight the importance of implementing adequate infection control measures in outpatient settings, especially when healthcare delivery moves from acute care facilities to outpatient clinics.

Host and microbial factors in kidney transplant recipients with Escherichia coli acute pyelonephritis or asymptomatic bacteriuria: a prospective study using whole-genome sequencing.

BACKGROUND: Urinary tract infection is the most common infection among kidney transplant recipients (KTRs). Many transplant physicians fear that host compromise will allow low-virulence strains to cause pyelonephritis in KTRs, so they often treat asymptomatic bacteriuria with antibiotics. Identification of the host/microbe factors that determine the clinical presentation (i.e. pyelonephritis versus asymptomatic bacteriuria) once an Escherichia coli strain enters a KTRs bladder could inform management decisions. METHODS: We prospectively collected all E. coli isolates causing either pyelonephritis or asymptomatic bacteriuria in KTRs at our institution (December 2012-June 2015). Whole-genome sequencing was used to assess bacterial characteristics (carriage of 48 virulence genes and phylogenetic and clonal background). Host parameters were also collected. RESULTS: We analysed 72 bacteriuria episodes in 54 KTRs (53 pyelonephritis, 19 asymptomatic bacteriuria). The pyelonephritis and asymptomatic bacteriuria isolates exhibited a similar total virulence gene count per isolate [median 18 (range 5-33) and 18 (5-30), respectively; P = 0.57] and for individual virulence genes differed significantly only for the prevalence of the pap operon (pyelonephritis 39%,versus asymptomatic bacteriuria 0%; P = 0.002). No other significant between-group differences were apparent for 86 other bacterial and host variables. CONCLUSIONS: Our findings suggest that bacterial adherence plays a role in the pathogenesis of pyelonephritis in KTRs despite significantly altered host urinary tract anatomy and weakened immunity. Whether KTRs might benefit from targeted therapies (e.g. vaccination or inhibitors of fimbrial adhesion) has yet to be studied.

Atopobium vaginae intrapartum bacteremia: A case report with a literature review.

Atopobium vaginae is an anaerobic Gram-positive bacterium recognized as a causative agent of bacterial vaginosis and associated with preterm delivery. Invasive infection and bacteremia have been rarely reported. We describe the case of a woman expecting her firstborn child who presented with a A. vaginae bacteremia during labor. Identification was performed using 16S rRNA gene sequencing. Both maternal and fetal outcomes were favorable due to the maternal treatment with amoxicillin-clavulanic acid. We identified three other cases in the literature with different fetal outcome. The genetic diversity of A. vaginae should be further explored in order to reveal potential strains with differential pathogenic potential.

Bacteria from Animals as a Pool of Antimicrobial Resistance Genes.

Antimicrobial agents are used in both veterinary and human medicine. The intensive use of antimicrobials in animals may promote the fixation of antimicrobial resistance genes in bacteria, which may be zoonotic or capable to transfer these genes to human-adapted pathogens or to human gut microbiota via direct contact, food or the environment. This review summarizes the current knowledge of the use of antimicrobial agents in animal health and explores the role of bacteria from animals as a pool of antimicrobial resistance genes for human bacteria. This review focused in relevant examples within the ESC(K)APE (Enterococcus faecium, Staphylococcus aureus, Clostridium difficile (Klebsiella pneumoniae), Acinetobacter baumannii, Pseudomonas aeruginosa, and Enterobacteriaceae) group of bacterial pathogens that are the leading cause of nosocomial infections throughout the world.

A Livestock-Associated, Multidrug-Resistant, Methicillin-Resistant Staphylococcus aureus Clonal Complex 97 Lineage Spreading in Dairy Cattle and Pigs in Italy.

Pandemic methicillin-resistant Staphylococcus aureus (MRSA) clonal complex 97 (CC97) lineages originated from livestock-to-human host jumps. In recent years, CC97 has become one of the major MRSA lineages detected in Italian farmed animals. The aim of this study was to characterize and analyze differences in MRSA and methicillin-susceptible S. aureus (MSSA) mainly of swine and bovine origins. Forty-seven CC97 isolates, 35 MRSA isolates, and 6 MSSA isolates from different Italian pig and cattle holdings; 5 pig MRSA isolates from Germany; and 1 human MSSA isolate from Spain were characterized by macrorestriction pulsed-field gel electrophoresis (PFGE) analysis, multilocus sequence typing (MLST), spa typing, staphylococcal cassette chromosome mec (SCCmec) typing, and antimicrobial resistance pattern analysis. Virulence and resistance genes were investigated by PCR and microarray analysis. Most of the isolates were of SCCmec type V (SCCmec V), except for two German MRSA isolates (SCCmec III). Five main clusters were identified by PFGE, with the German isolates (clusters I and II) showing 60.5% similarity with the Italian isolates, most of which (68.1%) grouped into cluster V. All CC97 isolates were Panton-Valentine leukocidin (PVL) negative, and a few (n = 7) tested positive for sak or scn. All MRSA isolates were multidrug resistant (MDR), and the main features were erm(B)- or erm(C)-mediated (n = 18) macrolide-lincosamide-streptogramin B resistance, vga(A)-mediated (n = 37) pleuromutilin resistance, fluoroquinolone resistance (n = 33), tet(K) in 32/37 tet(M)-positive isolates, and blaZ in almost all MRSA isolates. Few host-associated differences were detected among CC97 MRSA isolates: their extensive MDR nature in both pigs and dairy cattle may be a consequence of a spillback from pigs of a MRSA lineage that originated in cattle as MSSA and needs further investigation. Measures should be implemented at the farm level to prevent spillover to humans in intensive farming areas.

Biofilm formation of ica operon-positive Staphylococcus epidermidis from different sources.

Information on the prevalence of biofilm-related factors (PIA, Bhp, Aap, Embp) in Staphylococcus epidermidis of animal origin is scarce. In this study, 263 S. epidermidis isolates of diverse origin (animal, farmers, patients, and laboratory staff) were investigated for the presence of the ica operon (icaRADBC). The icaRADBC-positive isolates were further characterized by means of biofilm formation, presence of other biofilm-related genes, antimicrobial resistance, and population structure. Of all isolates, 28.5% (n = 75) were icaRADBC-positive, including 16.5% of animal origin, 29.1% farmer isolates, and 44.6% hospital-associated isolates (including patients and laboratory staff isolates). Most icaRADBC-positive isolates carried embp (n = 73), aap (n = 57), bhp (n = 22), and IS256 (n = 29). Statistical differences were found between animal and patient isolates for the presence of icaRADBC, bhp, and aap. No statistically significant relation was found between the presence of one or more genes and the level of biofilm formation. Most icaRADBC-positive isolates belonged to the clonal complex 5 (formerly 2) and most sequence types corresponded to types previously observed in community and nosocomial S. epidermidis populations. Although the prevalence of S. epidermidis in the nasal cavity of bovines and poultry is low, some isolates belong to STs related to ica-positive clinical strains.

Livestock-Associated Methicillin Resistant and Methicillin Susceptible Staphylococcus aureus Sequence Type (CC)1 in European Farmed Animals: High Genetic Relatedness of Isolates from Italian Cattle Herds and Humans.

Methicillin-resistant Staphylococcus aureus (MRSA) Sequence Type (ST)1, Clonal Complex(CC)1, SCCmec V is one of the major Livestock-Associated (LA-) lineages in pig farming industry in Italy and is associated with pigs in other European countries. Recently, it has been increasingly detected in Italian dairy cattle herds. The aim of this study was to analyse the differences between ST1 MRSA and methicillin-susceptible S. aureus (MSSA) from cattle and pig herds in Italy and Europe and human isolates. Sixty-tree animal isolates from different holdings and 20 human isolates were characterized by pulsed-field gel electrophoresis (PFGE), spa-typing, SCCmec typing, and by micro-array analysis for several virulence, antimicrobial resistance, and strain/host-specific marker genes. Three major PFGE clusters were detected. The bovine isolates shared a high (≥90% to 100%) similarity with human isolates and carried the same SCCmec type IVa. They often showed genetic features typical of human adaptation or present in human-associated CC1: Immune evasion cluster (IEC) genes sak and scn, or sea; sat and aphA3-mediated aminoglycoside resistance. Contrary, typical markers of porcine origin in Italy and Spain, like erm(A) mediated macrolide-lincosamide-streptograminB, and of vga(A)-mediated pleuromutilin resistance were always absent in human and bovine isolates. Most of ST(CC)1 MRSA from dairy cattle were multidrug-resistant and contained virulence and immunomodulatory genes associated with full capability of colonizing humans. As such, these strains may represent a greater human hazard than the porcine strains. The zoonotic capacity of CC1 LA-MRSA from livestock must be taken seriously and measures should be implemented at farm-level to prevent spill-over.

Extended-spectrum ß-lactamase- and AmpC ß-lactamase-producing D-tartrate-positive Salmonella enterica serovar Paratyphi B from broilers and human patients in Belgium, 2008-10.

OBJECTIVES: To characterize the genetic determinants responsible for extended-spectrum cephalosporin (ESC) resistance of d-tartrate-positive Salmonella enterica subsp. enterica serovar Paratyphi B (serovar Paratyphi B dT+) strains that have emerged in poultry and humans in Belgium during 2008-10. METHODS: The ESC resistance genes among non-redundant serovar Paratyphi B dT+ strains were determined using PCR and sequencing. ESC phenotypes were horizontally transferred by conjugation. Extended-spectrum ß-lactamase (ESBL)- or AmpC-carrying plasmids were typed by PCR-based replicon typing, plasmid multilocus sequence typing and restriction fragment length polymorphism. The genetic relationship of ESC-resistant strains was assessed by XbaI PFGE and multilocus sequence typing. RESULTS: Since 2008, the proportion of serovar Paratyphi B dT+ strains from broiler origin has increased significantly to reach 36.5% in 2010. Among 95 non-duplicate serovar Paratyphi B dT+ strains, 35% were resistant to ESCs. At the same time, a few ESC-resistant serovar Paratyphi B dT+ strains from humans were also detected in Belgium. The most prevalent ESBL gene, blaCTX-M-1, and the AmpC cephalosporinase gene blaCMY-2 were identified on various conjugative IncI1 plasmids of different sequence types and with different additional non-ß-lactam phenotypes. Interestingly, the blaCTX-M-2 gene was located on large multireplicon IncHI2/P plasmids. In addition, highly ESC-resistant strains contained both the ESBL CTX-M-2 and the AmpC CMY-2 encoded by the IncHI2/P and IncI1 plasmids, respectively. All ESC-resistant serovar Paratyphi B dT+ strains belonged to sequence type 28 and showed the common PFGE pattern X8, as well as the chromosomal class 2 integron cassette array dfrA1-sat2-aadA1 previously described in the European poultry-associated serovar Paratyphi B dT+ clonal population. CONCLUSIONS: This study showed that the clonal population of multidrug-resistant serovar Paratyphi B dT+, persisting in broilers in Belgium for the last decade, recently acquired various plasmid-borne ESC resistance determinants, constituting a major concern for public health. Further surveillance programmes and research are an absolute necessity to understand their epidemiology and to propose interventions to limit the spread of ESC- and multidrug-resistant Salmonella spp.

Food poisoning and Staphylococcus aureus enterotoxins.

Staphylococcus aureus produces a wide variety of toxins including staphylococcal enterotoxins (SEs; SEA to SEE, SEG to SEI, SER to SET) with demonstrated emetic activity, and staphylococcal-like (SEl) proteins, which are not emetic in a primate model (SElL and SElQ) or have yet to be tested (SElJ, SElK, SElM to SElP, SElU, SElU2 and SElV). SEs and SEls have been traditionally subdivided into classical (SEA to SEE) and new (SEG to SElU2) types. All possess superantigenic activity and are encoded by accessory genetic elements, including plasmids, prophages, pathogenicity islands, vSa genomic islands, or by genes located next to the staphylococcal cassette chromosome (SCC) implicated in methicillin resistance. SEs are a major cause of food poisoning, which typically occurs after ingestion of different foods, particularly processed meat and dairy products, contaminated with S. aureus by improper handling and subsequent storage at elevated temperatures. Symptoms are of rapid onset and include nausea and violent vomiting, with or without diarrhea. The illness is usually self-limiting and only occasionally it is severe enough to warrant hospitalization. SEA is the most common cause of staphylococcal food poisoning worldwide, but the involvement of other classical SEs has been also demonstrated. Of the new SE/SEls, only SEH have clearly been associated with food poisoning. However, genes encoding novel SEs as well as SEls with untested emetic activity are widely represented in S. aureus, and their role in pathogenesis may be underestimated.