Ahmed Samir

Novel antibacterial active quinolone-fluoroquinolone conjugates and 2D-QSAR studies.

Novel, quinolone-fluoroquinolone conjugates 10a-f, 11a-f, 13a-f and 14a-f with amino acid linkers were synthesized in good yields utilizing benzotriazole chemistry. Antibacterial bioassay showed the synthesized bis-conjugates exhibit anti-bacterial properties comparable with the parent drugs.

Cross-Species Surveillance of Leptospira in Domestic and Peri-Domestic Animals in Mahalla City, Gharbeya Governorate, Egypt

A survey of 179 animals (black rats, dogs, sheep, buffaloes, cattle, donkeys, weasels, and cats) for Leptospira infection was conducted in Mahalla City (Lower Egypt). Blood, urine, and kidney were collected and tested by culture, microscopic agglutination test (MAT), and/or polymerase chain reaction (PCR). Among rats, 26% were positive by PCR, including 7% that were also positive by culture for L. interrogans serovars Grippotyphosa, Pyrogenes, and Icterohaemorrhagiae. L. borpetersenii serovar Polonica was isolated for the first time in Egypt in three rats. MAT titers ≥ 1:800 were observed in 11% of rats and 12% of dogs. L. interrogans serovar Grippotyphosa was detected in one cat. Sheep and donkeys were negative for leptospirosis by all methods. Buffaloes and cattle were seropositive in 20% and 44% of animals, respectively. Data indicate that several pathogenic serovars are circulating in the animals, which may pose exposure risks and account for high rates of acute febrile illness.

Antimicrobial resistance in pathogens causing nosocomial bloodstream infections in university hospitals in Egypt

BACKGROUND Nosocomial bloodstream infections (BSIs) and antimicrobial resistance (AMR) are worldwide health care problems causing substantial patient morbidity and mortality. This study was conducted to identify bacterial pathogens isolated from nosocomial BSIs and determine their AMR patterns. METHODS An active surveillance program for BSIs was conducted in intensive care units in 3 large university hospitals in Egypt between September 1, 2006, and June 30, 2007. Infection prevention and control teams and link nurses in collaboration with intensive care physicians were looking actively to identify patients who acquired BSIs based on Centers for Disease Control and Prevention standard case definitions. Blood cultures were obtained from patients with suspected BSIs and processed to isolate bacteria and test their antimicrobial resistance. RESULTS During the 10-month active surveillance period, a total of 600 pathogens were isolated from blood cultures of 1,575 patients (38%). Of these 600 isolates, 386 (66%) were gram-negative, 178 (30%) were gram-positive, and 24 (4%) were budding yeasts. The gram-negative organisms included 162 (27%) Klebsiella pneumoniae and 23 (3.8%) Escherichia coli. Extended-spectrum β-lactamase enzymes were detected in 79% of the K pneumoniae isolates and 39% of the E coli isolates. Methicillin-resistant Staphylococcus aureus accounted for 60% of S aureus infections. CONCLUSIONS High rates of β-lactamase resistance and methicillin-resistant S aureus were found in the 3 Egyptian university hospitals studied. This study highlights the need for strengthening infection prevention and control programs, monitoring AMR at each facility, and developing policies for antibiotic use.

Synthesis and molecular modeling of antimicrobial active fluoroquinolone-pyrazine conjugates with amino acid linkers

Novel fluoroquinolone-pyrazine conjugates 7a-h with amino acid linkers were synthesized in good yields utilizing benzotriazole chemistry. Antimicrobial bioassay showed that the synthesized bis-conjugates have antimicrobial properties comparable to the parent drugs. Compound 7h showed superior antibacterial activity against Staphylococcus aureus and Streptococcus pyogenes (MIC=74.6 μM and 149.3 μM, respectively). This matched well with the estimated values obtained from 3D-pharmacophore and 2D-QSAR studies (MIC=67 μM and 92.9 μM, respectively).

Emerging of coagulase negative staphylococci as a cause of mastitis in dairy animals: An environmental hazard ☆

Abstract In Egypt, knowledge about the coagulase negative staphylococci (CNS) involved in mastitic animals is limited. CNS have emerged to be pathogens causing intramammary infections in Egyptian dairy herds. Therefore, the current study was conducted to investigate the occurrence of CNS in dairy ruminants (cattle, buffaloes, sheep and goats). A total of 884 quarter milk samples were investigated to study the prevalence of CNS among mastitic and subclinically mastitic cows, buffalo–cows, ewes and does in Egypt. Identification of the isolates was achieved using API staph test and polymerase chain reaction (PCR). CNS were isolated from the examined subclinical mastitic cattle, buffaloes, sheep and goats with percentages of 16.6%, 59.4%, 50% and 55.6%, respectively. Staphylococcus xylosus, Staphylococcus cohnii, Staphylococcus haemolyticus, Staphylococcus hominis, Staphylococcus saprophyticus, Staphylococcus chromogenes, Staphylococcus lentus, Staphylococcus lugdunensis and Staphylococcus simulans were identified as CNS that recovered from the examined milk samples. The CNS as mastitis-causing agents could not be neglected as they can cause substantial economic losses.

Methicillin‐Resistant Staphylococcus aureus: An Emerging Pathogen of Pets in Egypt with a Public Health Burden

Community-acquired methicillin-resistant Staphylococcus aureus (CA-MRSA) has emerged to be a pathogen of public health burden causing infections with significant concern. This study was conducted to investigate methicillin-resistant Staphylococcus aureus (MRSA) infection in pet dogs and cats as an emerging zoonosis that could be disseminated in the community. A total of 184 (nasal, oral, ear and wound) swabs were collected from 70 pet dogs and 48 pet cats, whereas 50 nasal and oral swabs were collected from 28 apparently healthy companion persons in intimate contact with pets and without history of hospitalization. All samples were cultured for the isolation and identification of Staphylococcus aureus using selective media, biochemical and serological tests, while isolates were identified as MRSA after antimicrobial susceptibility testing and determination of the MIC. PCR was applied using specific primers to confirm MRSA. Three MRSA isolates have been recovered from two dogs of 70 (2.9%) and one isolate from 28 examined persons (3.6%), while none of the examined cats yielded MRSA. Furthermore, we found that two MRSA isolates recovered from one diseased dog seemed to be hospital-associated methicillin-resistant Staphylococcus aureus (HA-MRSA), whereas the other dog isolate as well as the human isolate were considered as community-acquired (CA-MRSA). The occurrence of MRSA in apparently healthy and/or diseased pet dogs makes it an emerging veterinary pathogen which could be considered a public health burden if it is disseminated in our community outside hospitals.

Use of patient-specific Leptospira isolates in the diagnosis of leptospirosis employing microscopic agglutination testing (MAT)

Given the protean manifestations of leptospirosis, adequate laboratory support for diagnosis is necessary. Traditionally, the gold standard is the microscopic agglutination test (MAT) using a panel of Leptospira isolates representing a broad range of serogroups and serovars. It has been proposed that screening with serovars circulating in a region would enhance test performance. We assessed the diagnostic usefulness of MAT using both regionally obtained clinical Leptospira isolates and the specific isolates recovered from the tested patients. Serum obtained from 41 acute febrile patients (obtained on average 7.2 days [SD±5.2] after onset of fever) was tested using a standard panel of 24 serovars along with regional isolates recovered from human and animal blood cultures from different regions in Egypt and a patients own isolate, if available, to establish additional MAT panels. Serum samples tested by a standard 24 panel with a cut-off of >1:800 revealed five patients with positive serology. Only one patient had a positive result using a regional panel or patients own culture developed MAT. However, the serovar with the highest titers did not match the cultured serovar. Region-specific MATs did not appear to be reliable in detection of infection or in identifying the infecting serovar.

Macrocyclic peptidomimetics with antimicrobial activity: synthesis, bioassay, and molecular modeling studies.

Novel, cyclic peptidomimetics were synthesized by facile acylation reactions using benzotriazole chemistry. Microbiological testing of the synthesized compounds revealed an exceptionally high activity against Candida albicans with a minimum inhibitory concentration (MIC) two orders of magnitude lower than the MIC of the antifungal reference drug amphotericin B. A strikingly high activity was also observed against three Gram-negative bacterial strains (Pseudomonas aeruginosa, Klebsiella pneumoniae and Proteus vulgaris), two of which are known human pathogens. Thus the discovered chemotype is a potential polypharmacological agent. The toxicity against mammalian tumor cells was found to be low, as demonstrated in five different human cell lines (HeLa, cervical; PC-3, prostate; MCF-7, breast; HepG2, liver; and HCT-116, colon). The internal consistency of the experimental data was studied using 3D-pharmacophore and 2D-QSAR.

Prevalence, pathogenic capability, virulence genes, biofilm formation, and antibiotic resistance of Listeria in goat and sheep milk confirms need of hygienic milking conditions

Abstract Goat and sheep milk is consumed by human populations throughout the world; as a result, it has been proposed as an alternative, nutrient-rich milk to feed infants allergic to cow’s milk. Unfortunately, potentially harmful bacteria have not been thoroughly tested in goat or sheep milk. Listeria monocytogenes is a harmful bacterium that causes adverse health effects if ingested by humans. The purpose of this study was to estimate the prevalence and characterize the phenotype, genotype, virulence factors, biofilm formation, and antibiopotential of Listeria isolated from the milk of goat and sheep. Udder milk samples were collected from 107 goats and 102 sheep and screened for mastitis using the California mastitis test (CMT). Samples were then examined for the presence of pathogenic Listeria spp; if detected, the isolation of pathogenic Listeria (L. monocytogenes and Listeria ivanovii) was completed using isolation and identification techniques recommended by the International Organization for Standards (ISO 11290-1, 1996), in addition to serological, in vitro and in vivo pathogenicity tests. The isolates were subjected to PCR assay for virulence associated genes (hlyA, plcA, actA, and iap). Pathogenic Listeria spp. were isolated from 5·6% of goat and 3·9% sheep milk samples, with 33·3 and 25% of these selected samples respectively containing L. monocytogenes. The results of this study provide evidence of the low-likelihood of contamination leading to the presence of L. monocytogenes in raw goat and sheep milk; however, this study also confirmed a strong in vitro ability for biofilm formation and pathogenic capability of L. monocytogenes if discovered in the milk. L. monocytogenes may be present in goat and sheep milk and in order to reduce the exposure, hygienic milking conditions must be employed for the milk to be considered a safe alternative for human consumption.

Isolation of Enterotoxigenic Staphylococcus aureus from Pet Dogs and Cats: A Public Health Implication

Staphylococcus aureus is a globally distributed bacterium causing wide variety of illnesses in humans, which attributed to its ability to produce wide array of virulence factors, including enterotoxins that are responsible for staphylococcal food poisoning outbreaks. The current study was carried out to investigate the prevalence of enterotoxigenic S. aureus among pet dogs and cats and its public health implication. For this purpose, nasal, oral, and wound swabs were collected from 70 dogs and 47 cats, whereas nasal swabs were collected from 26 human contacts. All samples were examined for the presence of enterotoxigenic S. aureus by isolation of S. aureus in culture media and then tested by specific ELISA kits to detect the produced toxins in bacterial cultures. The prevalence of enterotoxigenic S. aureus was 10% and 2.1% for pet dogs and cats, respectively, whereas the nasal carriage rate in human contacts was 7.7%. The majority of animal isolates were obtained from mouth of the apparently healthy animals. All types of staphylococcal enterotoxins were detected in both animal and human isolates. High prevalence of enterotoxigenic S. aureus among pet dogs highlights the possibility of zoonotic transmission to human contacts leading to nasal and/or hand carriage of such strains; thus, pet animals may be incriminated in the epidemiology of household staphylococcal food poisoning outbreaks.