Resistance patterns of selected respiratory tract pathogens in Poland

Epidemiology of Streptococcus pyogenes upper respiratory tract infections in Poland (2003-2017)

Streptococcus pyogenes (group A Streptococcus, GAS) is a major human pathogen and causes every year over 600 millions upper respiratory tract onfections worldwide. Untreated or repeated infections may lead to post-infectional sequelae such as rheumatic heart disease, a major cause of GAS-mediated mortality. There is no comprehensive, longitudinal analysis of the M type distribution of upper respiratory tract strains isolated in Poland. Single reports describe rather their antibiotic resistance patterns or focus on the invasive isolates. Our goal was to analyse the clonal structure of the upper respiratory tract GAS isolated over multiple years in Poland. Our analysis revealed a clonal structure similar to the ones observed in high-income countries, with M1, M12, M89, M28, and M77 serotypes constituting over 80% of GAS strains. The M77 serotype is a major carrier of erythromycin resistance and is more often correlated with upper respiratory tract infections than other serotypes.

Antimicrobial resistance among Haemophilus influenzae isolates responsible for lower respiratory tract infections in Poland, 2005-2019

Haemophilus influenzae is a human-specific pathogen responsible for respiratory tract infections, meningitis, and sepsis. The study aimed to characterize antibiotic resistance in H. influenzae strains isolated from patients with lower respiratory tract infections over 15 years in Poland. The minimum inhibitory concentrations (MICs) of clinically relevant antibiotics were determined by broth microdilution method. Screening for beta-lactam resistance was performed in all isolates following EUCAST recommendation. Finally, relevant changes in penicillin-binding protein 3 (PBP3) were detected by PCR screening. Of the 1481 isolates collected between 2005 and 2019, 12.6%, 0.2%, 17.1%, and 0.2% were resistant to ampicillin, amoxicillin/clavulanate, cefuroxime, and ceftriaxone, respectively. Among them, 74.4% (1102/1481) of isolates were categorized as BLNAS (β-lactamase negative, ampicillin-susceptible), 13.0% (192/1481) as BLNAS with modified PBP3 (mutations in ftsI gene), 2.6% (39/1481) as BLNAR (β-lactamase negative, ampicillin-resistant), and 0.2% had PBP3 modifications typical for high-BLNAR. Production of β-lactamase characterized 9.7% of isolates (8.6% BLPAR-β-lactamase-positive, ampicillin-resistant, and 1.1% BLPACR-β-lactamase-positive, amoxicillin-clavulanate resistant). Three isolates with PBP3 modifications typical for high-BLNAR proved resistant to ceftriaxone (MIC > 0.125 mg/L). Resistance to ciprofloxacin, chloramphenicol, tetracycline, and trimethoprim-sulfamethoxazole was observed in 0.1%, 0.5%, 1.6%, and 24.7% of isolates, respectively. This is the first report of Polish H. influenzae isolates resistant to third-generation cephalosporins. Polish H. influenzae isolates demonstrate similar susceptibility trends as in many other countries. The substantial proportion of β-lactam-resistant isolates and the emergence of those resistant to third-generation cephalosporins are of great concern and should be under surveillance.

Relationships among streptococci from the mitis group, misidentified as Streptococcus pneumoniae

The aim of our study was to investigate phenotypic and genotypic features of streptococci misidentified (misID) as Streptococcus pneumoniae, obtained over 20 years from hospital patients in Poland. Sixty-three isolates demonstrating microbiological features typical for pneumococci (optochin susceptibility and/or bile solubility) were investigated by phenotypic tests, lytA and 16S rRNA gene polymorphism and whole-genome sequencing (WGS). All isolates had a 6-bp deletion in the lytA 3' terminus, characteristic for Mitis streptococc and all but two isolates lacked the pneumococcal signature cytosine at nucleotide position 203 in the 16S rRNA genes. The counterparts of psaA and ply were present in 100% and 81.0% of isolates, respectively; the spn9802 and spn9828 loci were characteristic for 49.2% and 38.1% of isolates, respectively. Phylogenetic trees and networks, based on the multilocus sequence analysis (MLSA) scheme, ribosomal multilocus sequence typing (rMLST) scheme and core-genome analysis, clearly separated investigated isolates from S. pneumoniae and demonstrated the polyclonal character of misID streptococci, associated with the Streptococcus pseudopneumoniae and Streptococcus mitis groups. While the S. pseudopneumoniae clade was relatively well defined in all three analyses, only the core-genome analysis revealed the presence of another cluster comprising a fraction of misID streptococci and a strain proposed elsewhere as a representative of a novel species in the Mitis group. Our findings point to complex phylogenetic and taxonomic relationships among S. mitis-like bacteria and support the notion that this group may in fact consist of several distinct species.

The Influence of National Guidelines on the Management of Community-Acquired Pneumonia in Children. Do Pediatricians Follow the Recommendations?

This is a retrospective study whose main objective was to analyze the influence of the Polish Guidelines for the Management of Respiratory Tract Infections of 2010 (PGMRTI) on in-hospital treatment of children with community-acquired pneumonia (CAP). Files from four Warsaw hospitals were reviewed to identify children with uncomplicated CAP, treated before (2008-2009) (pre-PGMRTI) and after (2011-2012) (post-PGMRTI) publication of the guidelines. Predefined data on the management were compared. A cohort of 2,359 children (1,081 pre-PGMRTI and 1,278 post-PGMRTI) was included. We found that co-amoxiclav was the most common first-line therapy in children >3 months of age (34.6% and 40.4% pre- and post-PGMRTI, respectively), followed by cefuroxime (31.8% and 20.9% pre- and post-PGMRTI, respectively; p < 0.0001) and macrolides (17.4% and 24.5% pre- and post-PGMRTI, respectively; p < 0.0001). Amoxicillin was rarely used (5.4% and 4.9%, pre- and post-PGMRTI, respectively). The study revealed an overuse of inhaled bronchodilators, corticosteroids, and mucoactive drugs. Blood diagnostic tests were applied to a significant percentage of patients: blood cultures (41.2% and 44.5% pre-and post-PGMRTI, respectively) and serology for atypical pathogens (27.9% and 44.9% pre-and post-PGMRTI, respectively; p < 0.0001). The number of follow-up chest X-rays increased (30.5% and 53.8% pre- and post-PGMRTI, respectively; p < 0.0001). In conclusion, the study demonstrates an unsatisfactory influence of the guidelines on in-hospital management of CAP in children. Despite an explicit recommendation for the use of amoxicillin, it was still underused. Other methods of education and guideline dissemination are needed to optimize the prescribing of antibiotics.

The return of Pfeiffer's bacillus: Rising incidence of ampicillin resistance in Haemophilus influenzae

Haemophilus influenzae, originally named Pfeiffer's bacillus after its discoverer Richard Pfeiffer in 1892, was a major risk for global health at the beginning of the 20th century, causing childhood pneumonia and invasive disease as well as otitis media and other upper respiratory tract infections. The implementation of the Hib vaccine, targeting the major capsule type of H. influenzae, almost eradicated the disease in countries that adapted the vaccination scheme. However, a rising number of infections are caused by non-typeable H. influenzae (NTHi), which has no capsule and against which the vaccine therefore provides no protection, as well as other serotypes equally not recognised by the vaccine. The first line of treatment is ampicillin, but there is a steady rise in ampicillin resistance. This is both through acquired as well as intrinsic mechanisms, and is cause for serious concern and the need for more surveillance. There are also increasing reports of new modifications of the intrinsic ampicillin-resistance mechanism leading to resistance against cephalosporins and carbapenems, the last line of well-tolerated drugs, and ampicillin-resistant H. influenzae was included in the recently released priority list of antibiotic-resistant bacteria by the WHO. This review provides an overview of ampicillin resistance prevalence and mechanisms in the context of our current knowledge about population dynamics of H. influenzae.

β-Lactam resistance among Haemophilus influenzae isolates in Poland

OBJECTIVES

Haemophilus influenzae is a human-specific Gram-negative coccobacillus responsible for a significant number of respiratory tract infections and severe invasive infections such as meningitis and sepsis. The purpose of this study was to characterise the mechanisms of β-lactam resistance among Polish H. influenzae isolates and to evaluate the resistance detection methods applied.

METHODS

This study was conducted on 117 Polish H. influenzae isolates collected in 2012. Minimum inhibitory concentrations were assessed by broth microdilution. All strains were evaluated using the disk diffusion method and the algorithm proposed by the Nordic Committee on Antimicrobial Susceptibility Testing (NordicAST). To detect changes in penicillin-binding protein 3 (PBP3), PCR screening was performed, followed by ftsI gene sequencing.

RESULTS

Neither β-lactamase production nor PBP3 alterations were demonstrated in 76 isolates (65.0%). Susceptibility to ampicillin, amoxicillin, amoxicillin/clavulanic acid, cefuroxime (intravenous) and ceftriaxone was observed in 70.9%, 78.6%, 98.3%, 82.9% and 100% of the isolates, respectively. β-Lactamase production characterised 21 isolates (17.9%). Screening PCR identified 20 isolates (17.1%) with PBP3 alterations, and according to subsequent ftsI sequencing all these strains were finally recognised as gBLNAR (genetically β-lactamase-negative, ampicillin-resistant), among which 65.0% were ampicillin-resistant. According to molecular classification of PBP3 alterations, 95.0% of gBLNAR belonged to group II, representing four subgroups IIa-IId.

CONCLUSIONS

Haemophilus influenzae resistance to antibiotics requires continuous attention, effective detection methods and a rational policy of antibiotic usage. The algorithm proposed by NordicAST can be applied in routine laboratory work, whereas sequencing of the ftsI gene may be useful in molecular epidemiology studies.

Antibiotic resistance of Streptococcus pneumoniae in children with acute otitis media treatment failure

OBJECTIVES

The emergence of antibiotic-resistant bacteria is a major cause of treatment failure in children with acute otitis media (AOM). This study aimed to analyze the types of bacterial strains in fluid isolated from the middle ear of children with AOM who did not respond to oral antibiotic treatment. We also determined the antibiotic resistance of the most frequently isolated bacterial strain (Streptococcus pneumoniae) found in these children.

METHODS

This was a prospective study of 157 children with AOM aged from 6 months to 7 years admitted due to unsuccessful oral antibiotic treatment. All children underwent a myringotomy, and samples of the middle ear fluid were collected for bacteriological examination.

RESULTS

Positive bacterial cultures were obtained in 104 patients (66.2%), with Streptococcus pneumoniae (39.69%), Haemophilus influenzae (16.03%) Staphylococcus aureus (16.03%), Staphylococcus haemolyticus (6.9%) and Streptococcus pyogenes (5.34%) found most frequently. The majority (65.4%) of S. pneumoniae strains were penicillin-intermediate-resistant or penicillin-resistant, and 67.2% strains of S. pneumoniae were multidrug-resistant.

CONCLUSIONS

We identified S. pneumoniae as the most frequently isolated pathogen from the middle ear in children with AOM treatment failure and determined that the majority of strains were antibiotic-resistant. We propose that the microbiological identification of bacterial strains and their degree of antibiotic resistance should be performed prior to therapy in order to choose the most appropriate antibiotic therapy for children with AOM treatment failure.

Macrolide-resistant Streptococcus pyogenes: prevalence and treatment strategies

Although penicillin remains the first-choice treatment for Streptococcus pyogenes infection, macrolides are important alternatives for allergic patients and lincosamides are recommended together with β-lactams in invasive infections. S. pyogenes may exhibit macrolide resistance because of active efflux (mef genes) or target modification (erm genes), the latter conferring cross resistance to lincosamides and streptogramin B. Worldwide, resistance is restricted to a limited number of genetic lineages, despite resistance genes being encoded on mobile genetic elements. For reasons that are not completely clear, resistance and the associated phenotypes are highly variable across countries. Although resistance remains high in several countries, particularly in Asia, an overall decreasing trend of resistance has been noted in recent years, mostly in Europe. This decrease is not always accompanied by declines in macrolide consumption, suggesting significant roles of other factors in determining the dynamics of macrolide-resistant clones. Continued surveillance is needed to obtain further insights into the forces governing macrolide resistance in S. pyogenes.

Non-typeable Haemophilus influenzae, an under-recognised pathogen

Non-typeable Haemophilus influenzae (NTHi) is a major cause of mucosal infections such as otitis media, sinusitis, conjunctivitis, and exacerbations of chronic obstructive pulmonary disease. In some regions, a strong causal relation links this pathogen with infections of the lower respiratory tract. In the past 20 years, a steady but constant increase has occurred in invasive NTHi worldwide, with perinatal infants, young children, and elderly people most at risk. Individuals with underlying comorbidities are most susceptible and infection is associated with high mortality. β-lactamase production is the predominant mechanism of resistance. However, the emergence and spread of β-lactamase-negative ampicillin-resistant strains in many regions of the world is of substantial concern, potentially necessitating changes to antibiotic treatment guidelines for community-acquired infections of the upper and lower respiratory tract and potentially increasing morbidity associated with invasive NTHi infections. Standardised surveillance protocols and typing methodologies to monitor this emerging pathogen should be implemented. International scientific organisations need to raise the profile of NTHi and to document the pathobiology of this microbe.

Increase of β-lactam-resistant invasive Haemophilus influenzae in Sweden, 1997 to 2010

The proportions of Haemophilus influenzae resistant to ampicillin and other β-lactam antibiotics have been low in Sweden compared to other countries in the Western world. However, a near-doubled proportion of nasopharyngeal Swedish H. influenzae isolates with resistance to β-lactams has been observed in the last decade. In the present study, the epidemiology and mechanisms of antimicrobial resistance of H. influenzae isolates from blood and cerebrospinal fluid in southern Sweden from 1997 to 2010 (n = 465) were studied. Antimicrobial susceptibility testing was performed using disk diffusion, and isolates with resistance to any tested β-lactam were further analyzed in detail. We identified a significantly increased (P = 0.03) proportion of β-lactam-resistant invasive H. influenzae during the study period, which was mainly attributed to a significant recent increase of β-lactamase-negative β-lactam-resistant isolates (P = 0.04). Furthermore, invasive β-lactamase-negative β-lactam-resistant H. influenzae isolates from 2007 and onwards were found in higher proportions than the corresponding proportions of nasopharyngeal isolates in a national survey. Multiple-locus sequence typing (MLST) of this group of isolates did not completely separate isolates with different resistance phenotypes. However, one cluster of β-lactamase-negative ampicillin-resistant (BLNAR) isolates was identified, and it included isolates from all geographical areas. A truncated variant of a β-lactamase gene with a promoter deletion, bla(TEM-1)-PΔ dominated among the β-lactamase-positive H. influenzae isolates. Our results show that the proportions of β-lactam-resistant invasive H. influenzae have increased in Sweden in the last decade.

Clonal spread of beta-lactamase-producing amoxicillin-clavulanate-resistant (BLPACR) strains of non-typeable Haemophilus influenzae among young children attending a day care in Japan

OBJECTIVE

Resistant strains of non-typeable Haemophilus influenzae (NTHi) are one of the principal causes of recurrent acute otitis media (otitis prone), rhinosinusitis, and pneumonia in young children. Beta-lactamase-nonproducing ampicillin-resistant (BLNAR) strains are particularly common in Japan, and beta-lactamase-producing amoxicillin-clavulanate resistant (BLPACR) strains are now emerging. We investigated the nasopharyngeal carriage status of these resistant strains among children attending a same day care center during a 10-year period.

METHODS

From 1999 to 2008, we obtained nasopharyngeal swab specimens from young children attending a same day care center and examined the incidence of resistant strains of NTHi. Antimicrobial resistance of NTHi was identified based on PCR analysis of mutation of the penicillin binding protein (PBP) genes. Pulsed-field gel electrophoresis (PFGE) was performed to examine the clonal relationship of each resistant strain.

RESULTS

The prevalence of resistant strains of NTHi among the children attending this day care has significantly increased during the past 10 years and most of this day care children recently have resistant strains with PBP gene mutations in their nasopharynx. Genetically BLPACR (gBLPACR) strains have rapidly increased since 2007 and PFGE analysis demonstrated that all gBLPACR were clonally identical. This is the first report of apparent clonal dissemination of gBLPACR strains of NTHi occurring in a certain environment such as day care.

CONCLUSIONS

The rapidly increasing prevalence of resistant strains, in particular gBLPACR, in this day care center may predict a high incidence of these resistant bacteria from clinical isolates in the near future and potential serious medical problems worldwide.

Expansion and evolution of the Streptococcus pneumoniae Spain9V-ST156 clonal complex in Poland

In this study, we analyzed 118 penicillin-nonsusceptible Streptococcus pneumoniae (PNSP) isolates (MICs, >or=0.12 microg/ml) recovered in Poland in 2003 to 2005 from patients with respiratory tract diseases and invasive infections. Seven different serotypes (14, 9V, 23F, 19F, 6B, 19A, and 6A, in order of descending frequency), seven alleles of the murM gene (murMA, murMB6, and the new murMB12 to -16 alleles), and 31 multilocus sequence types (STs) were observed. The vast majority of the PNSP isolates (90.7%) belonged to the international multiresistant clones, and among these, the Spain(9V)-ST156 clonal complex was the most prevalent (56 isolates) and was significantly overrepresented in invasive infections. The clone has been evolving rapidly, as demonstrated by the observed number of STs, the diversity in multiple-locus variable-number-tandem-repeat analysis (MLVA) types, and the polymorphism of pbp and pspA genes (coding for penicillin-binding proteins and the pneumococcal surface protein A, respectively). The presence and structure of the rlrA islet (encoding the pneumococcal pilus) were very well conserved. The Spain(9V)-ST156 clonal complex has been largely responsible for a decreasing susceptibility to penicillin among pneumococci in Poland in recent years, in spite of a relatively moderate antimicrobial use.

Automated peritoneal dialysis-associated peritonitis due to Haemophilus influenzae showing the BLNAR phenotype

A rare case of peritonitis due to beta-lactamase-negative, ampicillin-resistant Haemophilus influenzae is described in an 18-year-old male undergoing automated peritoneal dialysis. The infection was probably of respiratory origin. Two strains of H. influenzae cultured from peritoneal fluid and a nasal swab were indistinguishable by molecular methods. The patient was successfully treated with oral ciprofloxacin. The authors suggest that this species should be taken into account as the etiologic agent of peritoneal dialysis-associated peritonitis. Targeted antimicrobial therapy should be based on local antibiotic resistance patterns.

Antimicrobial susceptibility of Streptococcus pyogenes in Central, Eastern, and Baltic European Countries, 2005 to 2006: the cefditoren surveillance program

The in vitro activity of penicillin, ampicillin, cefditoren, cefotaxime, erythromycin, clarithromycin, and levofloxacin against 763 clinical isolates of Streptococcus pyogenes was determined. Clinically significant isolates collected from November 2005 to December 2006 in the Czech Republic, Slovakia, Hungary, Poland, Romania, Estonia, Latvia, and Lithuania (the latter 3 analyzed as Baltic countries) were studied. No resistance to beta-lactams and levofloxacin was found. The rate of erythromycin resistance in S. pyogenes varied among countries, being low (<10%) in Romania and Baltic countries, intermediate (10-20%) in Poland and Czech Republic, and high (>25%) in Hungary and Slovakia. The predominant (75.0%) erythromycin-resistant phenotype among S. pyogenes isolates was MLS(B). The identification of the prevalence of erythromycin resistance mechanism could have impact on the choice of empiric antibiotic therapy for the clinicians in such countries.