Nasopharyngeal Carriage of Streptococcus pneumoniae in Tunisian Healthy under-Five Children during a Three-Year Survey Period (2020 to 2022).

We aimed to assess the prevalence of nasopharyngeal pneumococcal carriage and to determine serotype distribution, antibiotic susceptibility patterns, and evolutionary dynamics of Streptococcus pneumoniae isolates in healthy under-five children. Nasopharyngeal swabs were collected from healthy children over three survey periods between 2020 and 2022. All pneumococcal isolates were serotyped and tested for antimicrobial susceptibility. A total of 309 S. pneumoniae isolates were collected, with an overall prevalence of nasopharyngeal pneumococcal carriage of 24.4% (CI95%: [22-26.8%]). These isolates were classified into 25 different serotypes. The most common serotypes were 14 (14.9%), 19F (12%), 6B (10.4%), and 23F (7.4%), which are covered by the PCV10 vaccine, as well as 19A (8.4%) and 6A (7.8%), which are covered by the PCV13 vaccine. A significant decrease in the proportion of serotype 19F (p = 0.001) and an increase in serotypes 19A (p = 0.034) and 6A (p = 0.029) were observed between the three survey periods. Multidrug resistance (MDR) was noted for 56.6% of the isolates. A significant association with antimicrobial resistance was observed for the most frequent serotypes, mainly serotype 19A. In conclusion, one-quarter of healthy under-five children in Tunisia carried S. pneumoniae in their nasopharynx. A dominance of vaccine serotypes significantly associated with antimicrobial resistance was recorded.

Group B Streptococcus and Perinatality in the South of Tunisia: Epidemiology, Serotype Distribution, and Antibiotic Susceptibility.

INTRODUCTION: In the lack of updated Tunisian epidemiological data, we sought to describe the epidemiology of Group B Streptococcus (GBS) in pregnant women and newborns. MATERIALS AND METHODS: A retrospective analysis of GBS neonatal invasive infections and a cross-sectional study evaluating the prevalence of maternal GBS colonization were conducted. GBS isolates were tested for antimicrobial susceptibility, serotyped, and assessed for the appurtenance to the hypervirulent ST17 clone. RESULTS: Of 98 neonates with GBS, early-onset GBS disease (EOD) comprised 83.7 and 16.3% were late-onset GBS disease (LOD). The prevalence of maternal GBS colonization was 27%. All GBS isolates were susceptible to penicillin. Serotype III predominated (42.6%) for neonatal invasive infections. GBS isolates belonging to the ST17 sequence type were found only as serotype III. CONCLUSION: This study documents the frequency of GBS EOD, the high rate of maternal GBS colonization, and the predominance of the hypervirulent clone type III/ST17 in infants.

Relationship Between Serotypes and Antimicrobial Nonsusceptibility of Streptococcus pneumoniae Clinical Isolates in Tunisia.

Streptococcus pneumoniae remains a significant cause of morbidity and mortality worldwide despite the overall success of the vaccine programs. In Tunisia, pneumococcal conjugate vaccines (PCV)10 was introduced in the national immunization program in April 2019. We sought to determine the relationship between serotypes and antimicrobial nonsusceptibility of S. pneumoniae isolates recovered from clinical samples in the prevaccination period in the south of Tunisia. A total of 504 nonduplicate S. pneumoniae isolates collected between 2012 and 2018 were tested for antimicrobial susceptibility, among them 439 (87.1%) were serotyped. The most common serotypes were 19F (17.8%), 14 (15.3%), 3 (9.1%), 19A (8.2%), and 23F (7.3%). The proportions of isolates with serotypes covered by PCV7, PCV10, and PCV13 were 55.4%, 56.3%, and 77.9%, respectively. Three-quarters (74.4%) of pneumococcal isolates were nonsusceptible to penicillin, and about half (54.8%) were multidrug resistant. Penicillin nonsusceptibility was observed for all 19A and 23F isolates, and was significantly associated with serotypes 19F (odds ratio [OR]: 33.7) and 14 (OR: 8.7). A significant association with multidrug resistance was noted for serotypes 19A (OR: 10), 19F (OR: 9.4), 23F (OR: 8.6), and 6B (OR: 5.2). The alarming rates of pneumococcal antimicrobial nonsusceptibility and the strong association with the most prevalent serotypes compel microbiologists to monitor the impact of the PCV10 introduced recently in our national immunization program.

Molecular epidemiology of extended-spectrum beta-lactamase-producing Escherichia coli in Tunisia and characterization of their virulence factors and plasmid addiction systems.

BACKGROUND: Extended-spectrum ß-lactamases (ESBLs), particularly CTX-M- type ESBLs, are among the most important resistance determinants spreading worldwide in Enterobacteriaceae. The aim of this study was to characterize a collection of 163 ESBL-producing Escherichia coli collected in Tunisia, their ESBL-encoding plasmids and plasmid associated addiction systems. RESULTS: The collection comprised 163 ESBL producers collected from two university hospitals of Sfax between 1989 and 2009. 118 isolates harbored blaCTX-M gene (101 blaCTX-M-15 gene and 17 blaCTX-M-14 gene). 49 isolates carried blaSHV-12 gene, 9 blaSHV-2a gene and only 3 blaTEM-26 gene. 16 isolates produced both CTX-M and SHV-12. The 101 CTX-M-15-producing isolates were significantly associated to phylogroup B2 and exhibiting a high number of virulence factors. 24 (23.7%) of the group B2 isolates belonged to clonal complex ST131. Pulsed-field gel electrophoresis (PFGE) typing revealed a genetic diversity of the isolates. 144 ESBL determinants were transferable mostly by conjugation. The majority of plasmid carrying blaCTX-M-15 genes (72/88) were assigned to various single replicon or multireplicon IncF types and had significantly a higher frequency of addiction systems, notably the VagCD module. CONCLUSION: This study demonstrates that the dissemination of CTX-M-15 producing E. coli in our setting was due to the spread of various IncF-type plasmids harboring multiple addiction systems, into related clones with high frequency of virulence determinants.

[Investigation of three nosocomial outbreaks of Serratia marcescens in an intensive care unit in Sfax-Tunisia]. / Investigation de trois épidémies d'infections nosocomiales à Serratia marcescens survenues dans le service de réanimation-CHU de Sfax, Tunisie.

UNLABELLED: THE AIM of the study was to type Serratia marcescens responsible for nosocomial outbreaks in an intensive care unit in Sfax -Tunisia. METHODS: The relatedness between S. marcescens isolates was studied by Pulsed field gel electrophoresis (PFGE). We included 56 strains of Serratia marcescens isolated from patients hospitalized in the intensive care unit during 2003 and 2004. Seven epidemiological unrelated strains of Serratia marcescens were also tested. Samples from environment and hands of the nursing and medical staff were collected and cultured to identify the source of contamination. RESULTS: All strains showed a wild type of antimicrobial susceptibility. PFGE typing revealed that three different clones were present. None of the cultures taken from hands of unit staff and from environmental samples yielded positive results for S. marcescens. CONCLUSION: We have confirmed the presence of three consecutive outbreaks caused by three genetically unrelated bacterial clones of Serratia marcescens in the intensive care unit ward. These outbreaks are closely related to the frequent use of colistin and the lack of measures of hygiene in this ward.

[Pseudomonas aeruginosa: a multicentric study of antibiotic resistance (1999-2000)]. / Pseudomonas aeruginosa: étude multicentrique de la résistance aux antibiotiques (1999-2000).

A retrospective multicentric study was carried out over a period of 2 years (1999-2000). 2659 strains of Pseudomonas aeruginosa were collected from 4 university hospitals (Charles Nicolle Hospital, Pediatric Hospital and National Centre of Bone Marrow Transplantation in Tunis, Habib Bourguiba Hospital in Sfax). Epidemiological profile and antibiotic susceptibility were analysed. All bacteria were identified by conventional methods and antibiotic susceptibility tests were performed according to CA-SFM guidelines. The strains were recovered essentially from surgical wards (33%) and intensive care units (22%). Pseudomonas aeruginosa was isolated mainly from pus (36%), urine (32%) and respiratory samples (18%). 25% of strains were resistant to ticarcilline, 18% to cefsulodine, 9% to ceftazidime, 14% to imipenem and amikacin and 25% to ciprofloxacin. Moreover, the resistance rates varied from hospital to hospital and from unit to another. The resistant strains were isolated particularly from urology and intensive care units: respectively 62% and 39% for ticarcilline; 26% and 13% for ceftazidime. The acquired resistance to b-lactams seems largely due to penicillinase production. The frequency of resistance to ceftazidime was the lowest and seems associated to chromosomal cephalosporinase over production.

[Antibiotic resistance among E. coli isolates from urinary tract infections (1999-2000): a multicenter study]. / Sensibilite aux antibiotiques des souches urinaires d'E. coli (1999-2000): resultats d'une étude multicentrique.

E. coli is the most frequently isolate species in community as well as in nosocomial acquired urinary tract infections (UTI). Trimethoprim-sulfamethoxazole (TMP-SMX), is commonly used as empiric treatment for managing uncomplicated UTI whereas the rate of resistance to amoxicilline is increasing. A multicentric retrospective study was conducted from January 1st 1999 to December 31st 2000 to evaluate the prevalence of E. coli isolates from UTI and to guide empiric therapies. Among 6994 urinary isolates, 62.6% were resistant to amoxicilline, this rate fell to 33.6% when amoxicilline was associated to clavulanic acide, 2.7% were producing extended spectrum b-lactamases (BLSE), higher than reported in France and USA. 37.3% were resistant to TMP-SMX. The high prevalence of antimicrobial resistance among UTI E. coli isolates emphasizes the necessity to review the empiric therapies. Fluoroquinolones can be considered as an alternative therapy according to their excellent tissue penetration and their wide spectrum of activity.

[Enterococcus faecalis: a multicenter study on antibiotic resistance]. / Enterococcus faecalis: étude multicentrique sur la résistance aux antibiotiques.

676 E. faecalis strains were listed over a period of 2 years from the Charles Nicolle hospital of Tunis (167 strains), the Habib Bourguiba hospital of Sfax (350 strains) and the National Centre of Bone marrow Transplantation of Tunis (159 strains). Antibiotic sensibility study was realized by the method of the antibiogram, E-test method and the search of penicillinase by cefinase. E. faecalis resulted essentially from services of onco-haematology (24%), external consultations (23%), surgery (18%) and medicine (15%). These strains were isolated especially from urines (54%), coprocultures (15%), bloodcultures (11%) and from pus (9%). Resistance acquired with these strains is raised for erythromycin, tetracyclin and chloramphenicol (81% to 86%), followed by high level resistance to gentamicine (37%). 0.1% of E. faecalis strains have a low level resistance to amoxicillin without production of penicillinase. No resistance to vancomycin was observed.

[Multidrug resistance in Klebsiella pneumoniae: multicenter study]. / Multiresistance aux antibiotiques de Klebsiella pneumoniae: etude multicentrique.

The extensive use of broad spectrum antibiotics, especially the third generation cephalosporins (C3G), was followed by the emergence of newer plasmid mediated betalactamases called extended spectrum betalactamases (ESBLs). To assess the impact of K. pneumoniae resistant to 3GC in Tunisia, this study was conducted in 3 teaching hospitals. A total of 1110 strains of K pneumoniae was collected. The antibiotics susceptibilities were tested by diffusion method using Mueller-Hinton agar. The quality control was regularly performed. I ESBLs producing solates were detected using the double-disc synergy test. Data analysis was done using the Whonet 4 software. 23.6% K. pneumoniae isolates showed phenotype pattern of ESBLs producers. The double-disc synergy test was positive in 75% of the cases. These isolates were recovered from hospitalized patients in different wards but mainly from pediatrics (23.6%), medicine (23.2%), surgery (22.9%), intensive care units (11%) and neonatology (11%). 54% were isolated from urines, 22% from blood cultures. These isolates remained susceptible to imipenem (100%) and most of them to cefoxitin (96.4%) but all had associated resistance to aminoglycosides, quinolones and trimethoprim-sulfamethoxazole. The prevalence of multidrug resistant K. pneumoniae is high. This resistance can be minimized by the implementation of infection control measures including handwashing and isolation procedures.

[Epidemiologic profile of Haemophilus influenzae infection in Tunisia]. / Profil épidémiologique des infections à H. influenzae en Tunisie.

Haemophilus influenzae, a commensal bacteria, is frequently incriminated in broncho--pulmonary surinfections and severe diseases as meningitis, pneumonia and septic arthritis, particularly in young children. A multicenter study was conducted to establish the epidemiological profile of Haemophilus influenzae diseases, to determine the rate of antibiotics resistance for guide therapeutic and preventive strategies. The identification was based on the requirements for X and V factors, and the serotype b determined by agglutination. The betalactamase production was done by nitrocefin test. Antimicrobial susceptibility testing was determined on Muller Hinton chocolate agar with isovitalex. During the two year period, (January 1998 December 1999), 192 isolates of H. Influenzae were collected, 61% were recovered from invasive infections (44 meningitis, 8 bacteremia, 2 arthritis). The serotype b was identified in 55.7% of cases, 67.3% were invasive strains. 24.5% of isolates were producing betalactamase particularly invasive serotype b strains. All isolates of H. influenzae were susceptible to cefotaxim and to ofloxacin. Resistance rates to other antibiotics were: erythromycin 56.2%, tetracyclin 10.3%, rifampin 12%, chloramphénicol 1%, cotrimoxazole 16.5%, 11.5% amikacin and 20% gentamicin. The incidence of meningitis remained frequent in our country, involving the introduction of the vaccination in official calendar. Nevertheless, the surveillance of H. influenzae invasives infections and the serotyping of isolates were necessary to evaluate the impact of the immunization.