Volatile organic compounds in headspace characterize isolated bacterial strains independent of growth medium or antibiotic sensitivity.

INTRODUCTION: Early and reliable determination of bacterial strain specificity and antibiotic resistance is critical to improve sepsis treatment. Previous research demonstrated the potential of headspace analysis of volatile organic compounds (VOCs) to differentiate between various microorganisms associated with pulmonary infections in vitro. This study evaluates whether VOC analysis can also discriminate antibiotic sensitive from resistant bacterial strains when cultured on varying growth media. METHODS: Both antibiotic-sensitive and -resistant strains of Pseudomonas aeruginosa, Staphylococcus aureus and Klebsiella pneumonia were cultured on 4 different growth media, i.e. Brain Heart Infusion, Marine Broth, Müller-Hinton and Trypticase Soy Agar. After overnight incubation at 37°C, the headspace air of the cultures was collected on stainless steel desorption tubes and analyzed by gas chromatography time-of-flight mass spectrometry (GC-tof-MS). Statistical analysis was performed using regularized multivariate analysis of variance and cross validation. RESULTS: The three bacterial species could be correctly recognized based on the differential presence of 14 VOCs (p<0.001). This discrimination was not influenced by the different growth media. Interestingly, a clear discrimination could be made between the antibiotic-resistant and -sensitive variant of Pseudomonas aeruginosa (p<0.001) based on their species-specific VOC signature. CONCLUSION: This study demonstrates that isolated microorganisms, including antibiotic-sensitive and -resistant strains of Pseudomonas aeruginosa, could be identified based on their excreted VOCs independent of the applied growth media. These findings suggest that the discriminating volatiles are associated with the microorganisms themselves rather than with their growth medium. This study exemplifies the potential of VOC analysis as diagnostic tool in medical microbiology. However, validation of our results in appropriate in vivo models is critical to improve translation of breath analysis to clinical applications.

Author Correction: Global phylogenetic analysis of Escherichia coli and plasmids carrying the mcr-1 gene indicates bacterial diversity but plasmid restriction.

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

Prevalence and risk factors for carriage of ESBL-producing Enterobacteriaceae in a population of Dutch travellers: A cross-sectional study.

BACKGROUND: We investigated prevalence and predictive factors for ESBL-E carriage in a population of mostly travellers prior to their travel (n = 2216). In addition, we examined ESBL genotype before travel and compared these to returning travellers. METHOD: A questionnaire and faecal sample were collected before travel, and a second faecal sample was collected immediately after travel. Faecal samples were analysed for ESBL-E, with genotypic characterization by PCR and sequencing. Risk factors for ESBL-E carriage prior to travel were identified by logistic regression analyses. RESULTS: Before travel, 136 participants (6.1%) were colonized with ESBL-E. Antibiotic use in the past three months (ORadjusted 2.57; 95% CI 1.59-4.16) and travel outside of Europe in the past year (1.92, 1.28-2.87) were risk factors for ESBL-E colonisation prior to travel. Travel outside of Europe carried the largest attributable risk (39.8%). Prior to travel 31.3% (40/128) of participants carried blaCTX-M 15 and 21.9% (28/128) blaCTX-M 14/18. In returning travellers 633 acquired ESBL-E of who 53.4% (338/633) acquired blaCTX-M 15 and 17.7% (112/633) blaCTX-M 14/18. CONCLUSION: In our population of Dutch travellers we found a pre-travel ESBL-E prevalence of 6.1%. Prior to travel, previous antibiotic use and travel outside of Europe were the strongest independent predictors for ESBL-E carriage, with travel outside of Europe carrying the largest attributable risk. Our molecular results suggest ESBL genes found in our study population prior to travel were in large part travel related.

Distribution of serotypes and patterns of antimicrobial resistance among commensal Streptococcus pneumoniae in nine European countries.

BACKGROUND: Streptococcus pneumoniae is a commensal of the human upper respiratory tract and a major cause of morbidity and mortality worldwide. This paper presents the distribution of serotypes and antimicrobial resistance in commensal S. pneumoniae strains cultured from healthy carriers older than four years of age in nine European countries. METHODS: Nasal swabs from healthy persons (age between 4 and 107 years old) were obtained by general practitioners from each country from November 2010 to August 2011. Swabs were cultured for S. pneumoniae using a standardized protocol. Antibiotic resistance was determined for isolated S. pneumoniae by broth microdilution. Capsular sequencing typing was used to identify serotypes, followed by serotype-specific PCR assays in case of ambiguous results. RESULTS: Thirty-two thousand one hundred sixty-one nasal swabs were collected from which 937 S. pneumoniae were isolated. A large variation in serotype distribution and antimicrobial resistant serotypes across the participating countries was observed. Pneumococcal vaccination was associated with a higher risk of pneumococcal colonization and antimicrobial resistance independently of country and vaccine used, either conjugate vaccine or PPV 23). CONCLUSIONS: Serotype 11A was the most common in carriage followed by serotypes 23A and 19A. The serotypes showing the highest resistance to penicillin were 14 followed by 19A. Serotype 15A showed the highest proportion of multidrug resistance.

Global phylogenetic analysis of Escherichia coli and plasmids carrying the mcr-1 gene indicates bacterial diversity but plasmid restriction.

To understand the dynamics behind the worldwide spread of the mcr-1 gene, we determined the population structure of Escherichia coli and of mobile genetic elements (MGEs) carrying the mcr-1 gene. After a systematic review of the literature we included 65 E. coli whole genome sequences (WGS), adding 6 recently sequenced travel related isolates, and 312 MLST profiles. We included 219 MGEs described in 7 Enterobacteriaceae species isolated from human, animal and environmental samples. Despite a high overall diversity, 2 lineages were observed in the E. coli population that may function as reservoirs of the mcr-1 gene, the largest of which was linked to ST10, a sequence type known for its ubiquity in human faecal samples and in food samples. No genotypic clustering by geographical origin or isolation source was observed. Amongst a total of 13 plasmid incompatibility types, the IncI2, IncX4 and IncHI2 plasmids accounted for more than 90% of MGEs carrying the mcr-1 gene. We observed significant geographical clustering with regional spread of IncHI2 plasmids in Europe and IncI2 in Asia. These findings point towards promiscuous spread of the mcr-1 gene by efficient horizontal gene transfer dominated by a limited number of plasmid incompatibility types.

Travel-related acquisition of diarrhoeagenic bacteria, enteral viruses and parasites in a prospective cohort of 98 Dutch travellers.

BACKGROUND: Limited prospective data are available on the acquisition of viral, bacterial and parasitic diarrhoeagenic agents by healthy individuals during travel. METHODS: To determine the frequency of travel associated acquisition of 19 pathogens in 98 intercontinental travellers, qPCR was used to detect 8 viral pathogens, 6 bacterial enteric pathogens and 5 parasite species in faecal samples collected immediately before and after travel. RESULTS: We found high pre-travel carriage rates of Blastocystis spp. and Dientamoeba fragilis of 32% and 19% respectively. Pre-travel prevalences of all other tested pathogens were below 3%. Blastocystis spp. (10%), Plesiomonas shigelloides (7%), D. fragilis (6%) and Shigella spp. (5%) were the most frequently acquired pathogens and acquisition of enteral viruses and hepatitis E virus in this relatively small group of travellers was rare or non-existent. CONCLUSIONS: Our findings suggest that the role of viruses as the cause of persisting traveller's diarrhoea is limited and bacterial pathogens are more likely as a cause of traveller's diarrhoea. The substantial proportion of travellers carrying Blastocystis spp. and D. fragilis before travel warrants cautious interpretation of positive samples in returning travellers with gastrointestinal complaints.

Import and spread of extended-spectrum ß-lactamase-producing Enterobacteriaceae by international travellers (COMBAT study): a prospective, multicentre cohort study.

BACKGROUND: International travel contributes to the dissemination of antimicrobial resistance. We investigated the acquisition of extended-spectrum ß-lactamase-producing Enterobacteriaceae (ESBL-E) during international travel, with a focus on predictive factors for acquisition, duration of colonisation, and probability of onward transmission. METHODS: Within the prospective, multicentre COMBAT study, 2001 Dutch travellers and 215 non-travelling household members were enrolled. Faecal samples and questionnaires on demographics, illnesses, and behaviour were collected before travel and immediately and 1, 3, 6, and 12 months after return. Samples were screened for the presence of ESBL-E. In post-travel samples, ESBL genes were sequenced and PCR with specific primers for plasmid-encoded ß-lactamase enzymes TEM, SHV, and CTX-M group 1, 2, 8, 9, and 25 was used to confirm the presence of ESBL genes in follow-up samples. Multivariable regression analyses and mathematical modelling were used to identify predictors for acquisition and sustained carriage, and to determine household transmission rates. This study is registered with ClinicalTrials.gov, number NCT01676974. FINDINGS: 633 (34·3%) of 1847 travellers who were ESBL negative before travel and had available samples after return had acquired ESBL-E during international travel (95% CI 32·1-36·5), with the highest number of acquisitions being among those who travelled to southern Asia in 136 of 181 (75·1%, 95% CI 68·4-80·9). Important predictors for acquisition of ESBL-E were antibiotic use during travel (adjusted odds ratio 2·69, 95% CI 1·79-4·05), traveller's diarrhoea that persisted after return (2·31, 1·42-3·76), and pre-existing chronic bowel disease (2·10, 1·13-3·90). The median duration of colonisation after travel was 30 days (95% CI 29-33). 65 (11·3%) of 577 remained colonised at 12 months. CTX-M enzyme group 9 ESBLs were associated with a significantly increased risk of sustained carriage (median duration 75 days, 95% CI 48-102, p=0·0001). Onward transmission was found in 13 (7·7%) of 168 household members. The probability of transmitting ESBL-E to another household member was 12% (95% CI 5-18). INTERPRETATION: Acquisition and spread of ESBL-E during and after international travel was substantial and worrisome. Travellers to areas with a high risk of ESBL-E acquisition should be viewed as potential carriers of ESBL-E for up to 12 months after return. FUNDING: Netherlands Organisation for Health Research and Development (ZonMw).

Can the composition of the intestinal microbiota predict the development of urinary tract infections?

AIM: To evaluate whether intestinal microbiota predicts the development of new-onset urinary tract infections (UTIs) in postmenopausal women with prior recurrent UTIs (rUTIs). PATIENTS & METHODS: Fecal samples (n = 40) originated from women with rUTI who received 12 months' prophylaxis of either trimethoprim-sulfamethoxazole (TMP-SMX) or lactobacilli. Microbial composition was assessed by 16S rRNA pyrosequencing. RESULTS: At baseline, fecal microbiota of women with zero and more than or equal to four UTIs during follow-up showed no significant differences. Only TMP-SMX prophylaxis resulted in reduced microbial diversity. Microbial structure of two samples from the same woman showed limited relatedness. CONCLUSION: In postmenopausal women with rUTI, the intestinal microbiota was not predictive for new-onset UTIs. Only TMP-SMX, and not lactobacilli, prophylaxis had effects on the microbial composition. Data in ENA:PRJEB13868.

Detection of the plasmid-mediated colistin-resistance gene mcr-1 in faecal metagenomes of Dutch travellers.

BACKGROUND: Recently, the first plasmid-mediated colistin-resistance gene, mcr-1, was reported. Colistin is increasingly used as an antibiotic of last resort for the treatment of infections caused by carbapenem-resistant bacteria, which have been rapidly disseminating worldwide in recent years. OBJECTIVES: The reported carriage rate of mcr-1 in humans remains sporadic thus far, except for those reported in Chinese populations. We aimed to determine its presence in the faecal metagenomes of healthy Dutch travellers between 2010 and 2012. METHODS: Faecal metagenomic DNA of pre- and post-travel samples from 122 healthy Dutch long-distance travellers was screened for the presence of mcr-1 using a TaqMan quantitative PCR assay, which was designed in this study. All positive samples were confirmed by sequencing of the amplicons. RESULTS: The mcr-1 gene was detected in 6 (4.9%, 95% CI = 2.1%-10.5%) of 122 healthy Dutch long-distance travellers after they had visited destinations in South(-east) Asia or southern Africa between 2011 and 2012. One of these participants was already found to be positive before travel. CONCLUSIONS: Our study highlights the potential of PCR-based targeted metagenomics as an unbiased and sensitive method to screen for the carriage of the mcr-1 gene and suggests that mcr-1 is widespread in various parts of the world. The observation that one participant was found to be positive before travel suggests that mcr-1 may already have disseminated to the microbiomes of Dutch residents at a low prevalence, warranting a more extensive investigation of its prevalence in the general population and possible sources.

Prolonged carriage and potential onward transmission of carbapenemase-producing Enterobacteriaceae in Dutch travelers.

AIM: The aim was to study acquisition and persistence of carbapenemase-producing Enterobacteriaceae (CPE) among travelers. MATERIALS & METHODS: Stools from 2001 travelers and 215 nontraveling household members, collected before and immediately post-travel as well as 1, 3, 6 and 12 months upon return, were screened for CPE. RESULTS: Five travelers, all visiting Asia outside the Indian subcontinent, acquired CPE. One traveler persistently carried the same OXA-244 CPE up to 6 months post-travel. Three months after travel, her co-traveling spouse also became positive for this OXA-244 CPE strain, suggesting clonal transmission within this household. CONCLUSION: Acquisition of CPE is not restricted to travelers to the Indian subcontinent and/or to travelers seeking healthcare during travel and can persist up to at least 6 months post-travel.

Prevalence and antibiotic resistance of commensal Streptococcus pneumoniae in nine European countries.

The human microbiota represents an important reservoir of antibiotic resistance. Moreover, the majority of antibiotics are prescribed in primary care. For this reason, we assessed the prevalence and antibiotic resistance of nasal carriage strains of Streptococcus pneumoniae, the most prevalent bacterial causative agent of community-acquired respiratory tract infections, in outpatients in nine European countries. Nasal swabs were collected between October 2010 and May 2011, from 32,770 patients, recruited by general practices in nine European countries. Overall prevalence of S. pneumoniae nasal carriage in the nine countries was 2.9%. The carriage was higher in men (3.7%) than in women (2.7%). Children (4-9 years) had a higher carriage prevalence (27.2%) compared with those older than 10 years (1.9%). The highest resistance observed was to cefaclor. The highest prevalence of multidrug resistance was found in Spain and the lowest prevalence was observed in Sweden.

Evaluation of phenotypic and molecular methods for identification of Streptococcus pneumoniae.

AIM: The objective of this study is to compare various Streptococcus pneumoniae identification methods. MATERIALS & METHODS: In total, 1371 putative S. pneumoniae isolates were tested with three phenotypic methods and a molecular-based method targeting a virulence factor (CpsA). We assessed the sensitivity and the specificity of each method and widely used S. pneumoniae identification algorithm. RESULTS: None of the methods or the identification algorithm used separately was able to correctly identify all S. pneumoniae isolates. Furthermore, a high rate of optochin resistance was found. CONCLUSIONS: We demonstrated the failure of the current S. pneumoniae identification methods and optochin susceptibility-based algorithm. In addition, the high rate of optochin resistance might justify the necessity of a close monitoring of optochin susceptibility.

Is a wound swab for microbiological analysis supportive in the clinical assessment of infection of a chronic wound?

AIM: To determine whether bacteriological analysis of a wound swab is supportive in the clinical assessment of infection of a chronic wound. METHODS: Patients attending an outpatient wound clinic who had endured a chronic wound for more than 3 weeks were clinically assessed for infection. In addition, standardized wound swabs were taken according to the Levine technique and the microbiological findings of the swabs compared with the clinical assessment of the wounds. RESULTS: There was no significant relationship between the clinical assessments of the chronic wounds and the qualitative or quantitative bacteriological results of the swabs. CONCLUSION: Microbiological analysis of wound swabs taken from chronic wounds to support clinical assessment of the wounds is waste of time and money. It may be preferable to assess chronic wounds clinically, however, validation studies of these signs and symptoms are needed.

Antibiotic Exposure and Other Risk Factors for Antimicrobial Resistance in Nasal Commensal Staphylococcus aureus: An Ecological Study in 8 European Countries.

OBJECTIVES: Antimicrobial resistance (AMR) has become a global public health concern which threatens the effective treatment of bacterial infections. Resistant Staphylococcus aureus (including MRSA) increasingly appears in individuals with no healthcare associated risks. Our study assessed risk factors for nasal carriage of resistant S. aureus in a multinational, healthy, community-based population, including ecological exposure to antibiotics. METHODS: Data were collected in eight European countries (Austria, Belgium, Croatia, France, Hungary, the Netherlands, Spain and Sweden). Commensal AMR patterns were assessed by collecting 28,929 nasal swabs from healthy persons (aged 4+). Ecological exposure to antibiotics was operationalized as systemic antibiotic treatment patterns, extracted from electronic medical records of primary care practices in which the participants were listed (10-27 per country). A multilevel analysis related AMR in nasal commensal S. aureus to antibiotic exposure and other risk factors (e.g. age and profession). RESULTS: Of the 6,093 S. aureus isolates, 77% showed resistance to at least one antibiotic. 7.1% exhibited multidrug resistance (defined as resistance to 3 or more antibiotic classes), and we found 78 cases MRSA (1.3%). A large variation in antibiotic exposure was found between and within countries. Younger age and a higher proportion of penicillin prescriptions in a practice were associated with higher odds for carriage of a resistant S. aureus. Also, we found higher multidrug resistance rates in participants working in healthcare or nurseries. CONCLUSIONS: This study indicates that in a population with no recent antibiotic use, the prescription behavior of the general practitioner affects the odds for carriage of a resistant S. aureus, highlighting the need for cautious prescribing in primary care. Finally, since variation in AMR could partly be explained on a national level, policy initiatives to decrease AMR should be encouraged at the national level within Europe.

Methicillin-resistant S. aureus (MRSA), extended-spectrum (ESBL)- and plasmid-mediated AmpC ß-lactamase -producing Gram-negative bacteria associated with skin and soft tissue infections in hospital and community settings.

AIM: To investigate the characteristics of meticillin-resistant S. aureus (MRSA), extended-spectrum (ESBL), and plasmid-mediated AmpC beta-lactamase producing Gram-negative bacteria causing skin and soft tissue infections (SSTIs) in hospital and outpatient settings of Zenica-Doboj Canton, Bosnia and Herzegovina. METHODS: Antibiotic susceptibility was determined by disc-diffusion and broth microdillution methods according to CLSI guidelines. MecA gene was detected by PCR, and genetic characterization of MRSA was performed using spa-typing and the algorithm based upon repeat patterns (BURP). Double-disk-synergy test was used to screen for ESBLs. PCR was used to detect blaESBL alleles. Genetic relatedness of the strains was tested by PFGE. RESULTS: Seventeen in-patients with MRSA, 13 with ESBL-producing Gram-negative bacteria and three patients co-infected with both, were detected. Five MRSA and 16 ESBL-producing Gram-negative bacteria were found in outpatient samples. Klebsiella spp. was isolated in 11 in- and seven outpatients. MLST CC152 was the most prevalent MRSA. Seven (38.9%) Klebsiella spp. yielded amplicons with primers specific for SHV, TEM-1 and CTX-M group 1 ß-lactamases. Eight K. pneumonia (44.4%) and 16 (64%) MRSA (including the in- and outpatient) strains were clonally related. CONCLUSION: The presence of MRSA and ESBL-producing organisms causing SSTIs in the community poses a substantial concern, due to the high morbidity and mortality associated with possible consequent hospital infections.

mecA-positive methicillin-sensitive Staphylococcus aureus clinical isolates in Zenica-Doboj Canton, Bosnia and Herzegovina.

Forty-four mecA-positive and eight mecA-negative Staphylococcus aureus isolates confirmed by PCR were further tested by disc-diffusion (DD) oxacillin and cefoxitin, oxacillin Epsilon (E)-test, and oxacillin and cefoxitin minimal inhibitory concentration (MIC) Strip methicillin-resistant phenotype in S. aureus (MRSA) tests. Among 44 mecA-positive S. aureus isolates, two (4·5%) were detected as MRSA by DD-oxacillin, 17 (38·6%) by DD-cefoxitin test, and seven (15·9%) by the E-test. In the cefoxitin MIC Strip MRSA test, 19 (43·2%) isolates were resistant. In the oxacillin MIC Strip MRSA test, 18 (40·9%) isolates were resistant and 26 (59·1%) were sensitive, i.e. oxacillin-sensitive MRSA (OS-MRSA) (MIC range 0·25-≤0·25 mg/l). Fifteen out of 26 OS-MRSA (57·7%) belonged to spa-CC 355/595, 78% of which belonged to the largest PFGE clone. Some discrepancies between the phenotypic methods for MRSA identification obtained in this study were caused by large proportion of OS-MRSA. Misidentification of OS-MRSA as MSSA might result in an appearance of highly resistant MRSA in patients treated with beta-lactam antibiotics.

Prevalence of chronic wounds and structural quality indicators of chronic wound care in Dutch nursing homes.

The aim of this study was to measure the prevalence of (infected) chronic wounds in Dutch nursing homes and to explore which signs and symptoms are used to diagnose infected chronic wounds. Moreover, it was to determine which structural quality indicators related to chronic wound care at ward and institutional levels were fulfilled. In April 2012, as part of the annual National Prevalence Measurement of Care Problems of Maastricht University [Landelijke Prevalentiemeting Zorgproblemen (LPZ)], a multi-center cross-sectional point-prevalence measurement was carried out together with an assessment of relevant care quality indicators. The prevalence was 4·2%; 16 of 72 (22%) chronic wounds were considered to be infected. Increase of exudate (81·3%; n = 13), erythema (68·8%; n = 11), pain (56·3%; n = 9) and wound recalcitrance (56·3%; n = 9) were considered to be diagnostic signs and symptoms of a chronic wound infection. Although at institutional level most quality indicators were fulfilled, at ward level this was not the case. Despite the relatively low number of residents, we consider our population as representative for the nursing home population. It may be an advantage to appoint specific ward nurses and to provide them specifically with knowledge and skills concerning chronic wounds.

Primary care treatment guidelines for skin infections in Europe: congruence with antimicrobial resistance found in commensal Staphylococcus aureus in the community.

BACKGROUND: Over 90% of antibiotics for human use in Europe are prescribed in primary care. We assessed the congruence between primary care treatment guidelines for skin infections and commensal Staphylococcus aureus (S. aureus) antimicrobial resistance levels in community-dwelling persons. METHODS: The prevalence of antimicrobial resistance in S. aureus was analysed by taking nose swabs from healthy primary care patients in nine European countries (total N = 32,032). Primary care treatment guidelines for bacterial skin infections were interpreted with respect to these antimicrobial resistance patterns. First- and second-choice recommendations were assessed and considered congruent if resistance to the antibiotic did not exceed 20%. RESULTS: We included primary care treatment guidelines for impetigo, cellulitis, folliculitis and furuncle. Treatment recommendations in all countries were consistent: most of the first-choice recommendations were beta-lactams, both for children and adults. Antimicrobial resistance levels were low, except for penicillin (on average 73% resistance). Considerable variation in antimicrobial resistance levels was found between countries, with Sweden displaying the lowest levels and Spain the highest. In some countries resistance to penicillin and azithromycin was significantly higher in children (4-17 years) compared with adults. CONCLUSIONS: Most of the first- and second-choice recommendations in the treatment guidelines for skin infections were congruent with commensal S. aureus antimicrobial resistance patterns in the community, except for two recommendations for penicillin. Given the variation in antimicrobial resistance levels between countries, age groups and health care settings, national data regarding antimicrobial resistance in the community should be taken into account when updating or developing primary care treatment guidelines.

Emergency (clonal spread) of methicillin-resistant Staphylococcus aureus (MRSA), extended spectrum (ESBL)--and AmpC beta-lactamase-producing Gram-negative bacteria infections at Pediatric Department, Bosnia and Herzegovina.

PURPOSE: Aim of this study was to investigate the prevalence of methicillin-resistant Staphylococcus aureus (MRSA), extended-spectrum (ESBL) and plasmid-mediated AmpC beta-lactamase producing Gram-negative bacteria in children. METHODS: Antibiotic susceptibility of MRSA and beta-lactamase producing Gram-negative bacteria was determined by disc diffusion and broth microdilution methods according to CLSI guidelines. Methicillin resistance was confirmed by the presence of mecA gene by PCR. The genetic characterization of S. aures was performed using spa-typing and the algorithm based upon repeat pattern (BURP). Double-disk synergy test was used to screen for ESBL production. PCR was used to detect bla ESBL alleles. Genetic relatedness of the strains was tested by pulsed-field gel electrophoresis (PFGE). RESULTS: Among 23 MRSA, 12 (52.2 %) were obtained from newborns. MLST CC152 (spa-CC 355-595) (Balkan clone) was the most prevalent, 20 (87 %) cases. Among 24 beta-lactamase producing Gram-negative bacteria, 10 (41.7 %) were obtained from each newborns and one-year-old children; 14 (58.3 %) were from urine. Among 11 Klebsiella strains isolated from urine eight (73 %) produced CTX-M-15, and one CTX-M-3 beta-lactamase. Twenty (83 %) of CTX-M producers were coproduced by other types of beta-lactamases. Fifteen (65.2 %) MRSA isolates were clonally related. Five clones among 13 K. pneumoniae isolates were detected by PFGE suggesting clonal spread of ß-lactamase producing Gram-negative bacteria. CONCLUSION: Pediatric infections caused by clonal spread of MRSA and beta-lactamase-producing Gram-negative bacteria are of major concern. Proper infection control measures should be implemented in order to avoid the transmission and major outbreaks.