Spectrum Of Antibiotic Susceptibility Research Articles

The role of R-plasmids in hospital strains of Proteus

The antibiotic sensitivity of Proteus strains isolated between 2017 and 2021 was investigated. A total of 85 Proteus strains were analyzed, revealing the widespread presence of poly-resistant forms of this pathogen. The examination of the antibiotic susceptibility spectrum in these strains demonstrated that those isolated from 2017 to 2021 exhibited similarities in their resistance profiles, with an expanding range of resistance observed towards gentamycin, kanamycin, carbenicillin, and others. The study identified that hospital-derived Proteus strains possess both conjugative and non-conjugative plasmids, distributed across different compatibility groups. It was shown that 55% of Proteus strains have conjugative R-plasmids, determining stability to streptomycin, gentamycin, carbenicillin, tetracycline, chloramphenicol, refer to T, J, M, N groups of incompatibility and have molecular masses 53.0; 33.0; 38.0; 49.0 MDa, respectively. In Proteus strains plasmids belonging to Inc-PI group of incompatibility were found. Furthermore, non-conjugative R-plasmids were identified in Proteus strains, conferring stability to tetracycline and streptomycin, with molecular masses of 7.2 and 5.8 MDa, respectively. Thus, the investigation of Proteus strains isolated in two clinics highlighted the participation of both conjugative and non-conjugative resistance plasmids in the development of hospital-associated Proteus strains.

ANTIBIOTIC RESISTANCE PROFILES IN ACINETOBACTER BAUMANNII STRAINS ISOLATED FROM WASTEWATER IN SOUTHERN ROMANIA

Introduction: Given the high mobility of antibiotic resistance genes and their propensity for transmission among human, animal, and environmental reservoirs, managing the risks associated with antibiotic resistance is a challenging goal. The Acinetobacter species are among the most relevant bacteria with clinical significance and special abilities to acquire resistance mechanisms and to survive in diverse environmental conditions. A particular interest in A. baumannii strains is their association with chronic nosocomial infections, such as pneumonia, urinary tract infections, soft tissue infections, or nosocomial meningitis. Objectives: This study aimed to compare the antibiotic resistance profiles of 48 A. baumannii strains collected in 2020 and 2021 from a wastewater treatment plant (WWTP) in the southern region of Romania and evaluate the role of WWTP in disseminating antibiotic resistance in the aquatic environment. Methods: The detection and quantification of resistant bacteria were achieved using the filter membrane technique and chromogenic media supplemented with antibiotics. The analysis and identification of the bacterial species present in the collected samples were carried out using Bruker MALDI-TOF spectrometry. The antibiotic susceptibility spectrum was tested by the standardized disc diffusion method. Results: Among the analyzed strains, 47 presented resistance phenotypes of clinical and epidemiological importance, 15 of them being MDR, 9 XDR, and 23 PDR. Conclusion: Our results demonstrate the role of the WWTP in the accumulation and dissemination of antimicrobial resistance from the clinical and other anthropic sources into the aquatic environment, as well as the potential impact of the COVID-19 pandemic on the evolution of this phenomenon.

Assessment of Microbiological Environment and the Level of Antibiotic Resistance in a Multidisciplinary Hospital

The objective: to determine the incidence and drug sensitivity of the main pathogens causing community-acquired and nosocomial infections in patients staying in a multidisciplinary hospital.Subjects and Methods: a retrospective study of the microbiological population in patients of a multidisciplinary hospital was carried out. The period over 3 years was assessed. 3,954 samples of biological materials from various sites were studied.Results: gram-positive bacteria prevailed in the general structure of microbial environment of patients – Staphylococcus aureus (28%), and Enterococcus faecalis (10%), as well as gram-negative – Escherichia coli (26%), and Klebsiella pneumoniae (13%). The majority of non-fermenting gram-negative microorganisms isolated from patients in the intensive care unit demonstrated multiple resistance and quantitatively prevailed over those in surgery units. The spectrum of antibiotic susceptibility of microorganisms of the same species isolated from patients of therapy and surgery departments differed.

Microbiological spectrum of ocular infections in patients of tertiary care eye hospital of Punjab

Eye is a complex and sensitive organ and is therefore more vulnerable to trauma and various infections ocular infections are one of the most commonly encountered infections. Any part of the eye can be infected by bacteria, fungi, parasites or viruses. In order to minimize the ocular morbidity and mortality, timely antimicrobial treatment must be initiated on the basis of clinical and microbial evaluation. For specific antibacterial treatment, isolation and identification of bacterial pathogens along with antibiotic susceptibility spectrum is essential. Hence, this study was undertaken to isolate and identify the bacterial and fungal pathogens responsible for the development of ocular infections and to determine their in vitro susceptibilities to commonly used antibiotics. A total of 203 samples of suspected ocular infections comprising 117 conjunctival swabs, 34 corneal specimens, 24 lacrimal pus samples and 28 vitreous specimens were analysed. Out of them 102(50.1%) showed growth. 82(40%) were bacterial and 21(10.3%) were fungal isolates. Due to the emergence of drug resistance it is imperative that all ophthalmological samples must be tested for antibiotic resistance as far as possible. Indiscriminate use of over the counter antibiotic eye formulations should be avoided and also it is important to know the changing pattern of pathogens.

Characterisation of a potential probiotic strain Paracoccus marcusii KGP and its application in whey bioremediation.

Whey, the main by-product obtained from the manufacture of cheese, which contains a very high organic load (mainly due to the lactose content), is not easily degradable and creates concern over environmental issues. Hydrolysis of lactose present in whey and conversion of whey lactose into valuable products such as bioethanol, sweet syrup, and animal feed offers the possibility of whey bioremediation. The increasing need for bioremediation in the dairy industry has compelled researchers to search for a novel source of β-galactosidase with diverse properties. In the present study, the bacterium Paracoccus marcusii KGP producing β-galactosidase was subjected to morphological, biochemical, and probiotic characterisation. The bacterial isolate was found to be non-pathogenic and resistant to low pH (3 and 4), bile salts (0.2%), salt (10%), pepsin (at pH 3), and pancreatin (at pH 8). Further characterisation revealed that the bacteria have a good auto-aggregation ability (40% at 24h), higher hydrophobicity (chloroform-60%, xylene-50%, and ethyl acetate-40%) and a broad spectrum of antibiotic susceptibility. The highest growth of P. marcusii KGP was achieved at pH 7 and 28°C, and the yeast extract, galactose, and MgSO4 were the best for the growth of the bacterial cells. The bacterium KGP was able to utilise whey as a substrate for its growth with good β-galactosidase production potential. Furthermore, the β-galactosidase extracted from the isolate KGP could hydrolyse 47% whey lactose efficiently at 50°C. The study thus reveals the potential application of β-galactosidase from P. marcusii KGP in whey bioremediation.

Antibiotic-Resistant Uropathogenic <i>Escherichia coli</i> Isolated from Children with Congenital Abnormalities of the Kidneys and Urinary Tract

Uropathogenic Escherichia coli (UPEC) is a serious health problem worldwide. UPEC's multiple drug resistance combined with virulence factors is a cause of serious concern. In childhood, urinary tract infections are of particular importance, since they can occur against the background of long-term unrecognized congenital anomalies of the kidneys and urinary tract. Of the 106 UPEC clinical isolates, 63.2% of cultures were isolated from girls' urine samples and 36.8% from boys' urine samples, which corresponds to a 1.7: 1 ratio. The antibiotic resistance of the isolated UPEC cultures was assessed in relation to 12 antimicrobial drugs. Among the tested cultures, 49% were multidrug-resistant and 20.75% were found to be resistant to imipenem. Phenotypic analysis of antibiotic susceptibility spectrum of uropathogenic E.coli (n=106) indicates a high percentage of occurrence of multi-resistant UPEC strains (49%) and imipenem-resistant UPEC strains (20.75%) among children of all age groups.

Pattern of antimicrobial sensitivity in Enterococcus in case of urinary tract infection, 5 years experiences in a tertiary care hospital

Introduction: Urinary tract infection is very common in our community mostly in females and enterococcal infection is very frequent. There is gradual development of resistance against this organism thus narrowing the spectrum of susceptibility. Aims: So, the aim of this study to detect the spectrum of sensitivity pattern in case of enterococcus in case of urinary tract infection. Materials and Methods: In this retrospective cross sectional study, morning midstream clean-catch urine form total 1550 symptomatic patients was studied for the spectrum of antibiotic susceptibility according to Clinical & laboratory Standard Institute (CLSI) guideline. Results: Total 189 patients were infected with enterococci. They showed sensitivity to Vancomycin (87.83%), Teicoplanin (85.18%), Lenazolid (84.12%) and nitrofurantoin (74.07%), and moderate degree of sensitivity in piperacillin-tazobactam (67.19%), imipenem (64.60%) and gentamicin (46.56%) and Amoxycillin-clavulanic acid (54.49%). Conclusion: Proper antibiotic-stewardship is ultimate requirement to prevent the development of bacterial resistance. So, regular surveillance as well as monitoring is very much necessary to update the knowledge about the susceptibility pattern of urinary pathogens which will guide the therapy. Keyword: Enterococcus, Symptomatic urinary tract infections, Culture and sensitivity, Tertiary medical centre

Extended spectrum of antibiotic susceptibility for tuberculosis, Djibouti

In the Horn of Africa, there is a high prevalence of tuberculosis that is reported to be partly driven by multidrug-resistant (MDR) Mycobacterium tuberculosis strictu sensu strains. We conducted a prospective study to investigate M. tuberculosis complex species causing tuberculosis in Djibouti, and their in vitro susceptibility to standard anti-tuberculous antibiotics in addition to clofazimine, minocycline, chloramphenicol and sulfadiazine. Among the 118 mycobacteria isolates from 118 successive patients with suspected pulmonary tuberculosis, 111 strains of M. tuberculosis, five Mycobacterium canettii, one ‘Mycobacterium simulans’ and one Mycobacterium kansasii were identified. Drug-susceptibility tests performed on the first 78 isolates yielded nine MDR M. tuberculosis isolates. All isolates were fully susceptible to clofazimine, minocycline and chloramphenicol, and 75 of 78 isolates were susceptible to sulfadiazine. In the Horn of Africa, patients with confirmed pulmonary tuberculosis caused by an in vitro susceptible strain may benefit from anti-leprosy drugs, sulfamides and phenicol antibiotics.

Development of a genetic system for Marinobacter adhaerens HP15 involved in marine aggregate formation by interacting with diatom cells

Diatom aggregation is substantial for organic carbon flux from the photic zone to deeper waters. Many heterotrophic bacteria ubiquitously found in diverse marine environments interact with marine algae and thus impact organic matter and energy cycling in the ocean. In particular, Marinobacter adhaerens HP15 induces aggregate formation while interacting with the diatom, Thalassiosira weissflogii. To study this effect at the molecular level, a genetic tool system was developed for strain HP15. The antibiotic susceptibility spectrum of this organism was determined and electroporation and conjugation protocols were established. Among various plasmids of different incompatibility groups, only two were shown to replicate in M. adhaerens. 1.4×10−3 transconjugants per recipient were obtained for a broad-host-range vector. Electroporation efficiency corresponded to 1.1×105CFU per μg of DNA. Transposon and gene-specific mutageneses were conducted for flagellum biosynthetic genes. Mutant phenotypes were confirmed by swimming assay and microscopy. Successful expression of two reporter genes in strain HP15 revealed useful tools for gene expression analyses, which will allow studying diverse bacteria–algae interactions at the molecular level and hence to gain a mechanistic understanding of micro-scale processes underlying ocean basin-scale processes. This study is the first report for the genetic manipulation of a Marinobacter species which specifically interacts with marine diatoms and serves as model to additionally analyze various previously reported Marinobacter–algae interactions in depth.

Bacterial Isolates from Blood Samples of Patients in University of Benin Teaching Hospital Benin City, Edo State, Nigeria.

The presence of bacteria in the blood stream results in a condition known as bacteremia. This condition is associated with pyrexia of unknown origin (PUO). The study seeks to determine the bacterial etiology of bloodstream infections and their susceptibility profile in a tertiary healthcare institution. The design was prospective and crosssectional. Specimens were obtained from patients in no particular selection order except that they were consecutively obtained. The study was carried out in a tertiary healthcare institution which is equipped with a standard microbiology laboratory. Patients seen at the various facilities in the hospital were used for the study. They numbered one thousand, six hundred and seventy (1,670) patients. This was during the period October 2008 to September 2009. The patient population was 1,500 (89.2%) infants while adults were 170 (10.8%). 1ml of venous blood was aseptically inoculated into two blood culture bottles, brain heart infusion broth and thioglycollate broth while giving great attention to sterile process. They were incubated overnight at 37 C and were examined daily for growth. Growth is usually characterized by gas bubbles or turbidity. If there was indication of growth either in the brain-heart infusion broth or the thioglycollate broth or both; gram staining and microscopy were prepared and read. The thioglychollate broth was sub cultured onto blood agar plate for anaerobic incubation, while the brain heart infusion broth was sub cultured onto chocolate, blood agar and McConkey agar for aerobic incubation. The anaerobic incubation was done by putting the culture plates into an anaerobic jar and filling it with hydrogen gas. This was incubated at 37 C overnight. The organisms isolated were identified to species level using the protocol of Cowan and Steel. The antibiotic susceptibility spectrum of the isolates was determined using the agar diffusion method of Bauer and Kirby. Eleven bacterial species were isolated in the study and they varied widely in their antibiotic susceptibilities. Ofloxacin exhibited the highest antimicrobial activity. Staphylococcus aureus was 56.3% susceptible to oxacillin. The study isolated the common bacteria involved in bacteremia and determined their susceptibility profile, and also suggested some control measures. Keywords: Bacteremia; Pyrexia of unknown origin; antibiotic susceptibilities,

Analysis of cefoxitin-sensitive, penicillin-resistant Staphylococcus tested by disk diffusion method

Objective To evalue the ability of detecting the resistance of cefoxitin-sensitive,penicillin-resistant Staphylococcus by different methods and analyze the antibiotic susceptibility spectrum of coagulase-negative Staphylococcus which are non-mecA-mediated oxacillin resistance. Methods All the isolates were collected from Huashan hospital between 2007 and 2009. The isolates were recovered from various clinical sources, including respiratory tract, urine, secretion and sterile fluids samples. The oxacillin susceptibility of Staphylococcus aureus was determined by cefoxitin disk diffusion test, cefoxitin MIC test,oxacillin disk diffusion test and oxacillin MIC test Likewise, the oxacillin susceptibility of coagulasenegative Staphylococcus was determined by cefoxitin disk diffusion test and oxacillin MIC test. All the isolates with sensitive to cefoxitin were screened for the mec A gene by PCR Finally, the MIC of non-mecA-mediated oxacillin-resistant Staphylococcus were determined. Results Among 255 cefoxitin disk diffusion test sensitive and penicillin-resistant Staphylococcus aureus, 6 isolates were intermediated to oxacillin and 4 were resistant by oxacillin disk diffusion test, but all the isolates were sensitive by the cefoxitin disk diffusion test,cefoxitin MIC test and oxacillin MIC test. Among 75 cefoxitin disk diffusion test sensitive and penicillin-resistant coagulase-negative Staphylococcus, 16 isolates were resistant to oxacillin by oxacillin MIC method and 4 carried mecA gene. Among 12 non-mecA-mediated oxacillin-resistant Staphylococcus, the susceptible isolates of gentamicin is 10, clindamycin is 8, ciprofloxacin is 11, erythrornycin is 6, trimethoprim/sulfamethoxazo]e is 11 ,and cephalosporins, teicoplaninl, vancomycin, piperacillin/tazobactam, tetracycline are all 12. Conclusions The cefoxitin disk diffusion test can reliably predict mecA-mediated oxacillin resistant Staphylococcus aureus. It would be best to combine cefoxitin disk diffusion test and oxacillin MIC test to improve accuracy of detection of mecA-mediated oxacillin resistant coagulase-negative Staphylococcus.Furthermore, infections due to the non-mecA-mediated oxacillin resistant coagulase-negative Staphylococcus can be treated by penicillinase-stable penicillins, β-lactam/β-lactam inhibitor combinations, relevant cephems and carbapenems. Key words: Staphylococcus aureus; Penicillin resistance; Cefoxitin; Disk diffusion antimicrobial tests

1396 Epidemiology and Antibiotic Susceptibility Spectrum in Upec From Urine in Children Suspected to Uti in Mofid Children Hospital

1396 Epidemiology and Antibiotic Susceptibility Spectrum in Upec From Urine in Children Suspected to Uti in Mofid Children Hospital

Antimicrobial susceptibility of Borrelia burgdorferi sensu lato: What we know, what we don't know, and what we need to know

Human Lyme borreliosis is a multisystem disorder that can progress in stages and is transmitted by ticks of the Ixodes ricinus complex infected with the spirochete Borrelia burgdorferi sensu lato. Today, Lyme borreliosis is regarded as the most important human tickborne illness in the northern hemisphere. Soon after the causative agent was correctly identified and successfully isolated in 1982, antibiotic treatment was shown to be effective and since then a variety of in vitro and in vivo studies have been performed to further characterize the activity of antimicrobial agents against B. burgdorferi s.l. Although many antimicrobial agents have been tested for their in vitro activity against borreliae, the full spectrum of antibiotic susceptibility in B. burgdorferi s.l. has not been defined for many compounds. Moreover, our current understanding of possible antimicrobial resistance mechanisms in B. burgdorferi s.l. is limited and is largely founded on in vitro experiments on relatively few borrelial isolates. This review will summarize what is and what is not known about antimicrobial resistance in B. burgdorferi s.l. and will discuss open questions that continue to fuel the current debate on treatment-resistant Lyme borreliosis.

Haloferax alexandrinus sp. nov., an extremely halophilic canthaxanthin-producing archaeon from a solar saltern in Alexandria (Egypt).

An extremely halophilic red micro-organism designated strain TM(T) was isolated from a solar saltern in Alexandria, Egypt. The micro-organism stains gram-negative, is very pleomorphic, non-motile and strictly aerobic and requires at least 10 g NaCl l(-1) for growth. The growth optimum is 250 g NaCl l(-1). Growth is also observed over a wide range of MgSO4 concentrations (10-40 g l(-1)). Aerobic reduction of nitrate without gas production was detected. Cells grew aerobically in a minimal salts medium containing ammonium chloride and glucose. Strain TM(T) produced acid from fructose, glucose, rhamnose, maltose and glycerol. The G+C content of the DNA was 59.5+/-0.3 mol %. On the basis of polar lipid analysis, the isolate belonged to the genus Haloferax. Analysis of the 16S rDNA sequence showed the highest similarity (>99%) to be to the type strain Haloferax volcanii. Although the spectrum of antibiotic susceptibility was similar to that of validly described species of the genus Haloferax, the strain could be distinguished from them by its different response to josamycin and rifampicin. Strain TM(T) is unique within the genus Haloferax in producing canthaxanthin. Comparative analysis of phenotypic properties and DNA-DNA hybridization between strain TM(T) and Haloferax species supported the conclusion that TM(T) is a novel species within this genus, for which the name Haloferax alexandrinus sp. nov. is proposed. The type strain is TM(T) (= JCM 10717T = IFO 16590T).

Colorimetric in vitro susceptibility testing of penicillins, cephalosporins, macrolides, streptogramins, tetracyclines, and aminoglycosides against Borrelia burgdorferi isolates

The spectrum of antibiotic susceptibility of Borrelia burgdorferi has been only partially defined. In the present study the effectiveness of 12 antimicrobials, belonging to six different antibiotic classes have been tested against Borrelia burgdorferi s.s. ( N=3), Borrelia garinii ( N=3), Borrelia afzelii ( N=3), Borrelia valaisiana ( N=1), and Borrelia bissettii ( N=1) isolates. These isolates were analysed by a new standardised colorimetric minimal inhibitory concentration (MIC) method based upon colour changes that result from actively metabolizing spirochaetes after 72 h of incubation. Piperacillin (MIC90: 0.08 mg/l), ceftriaxone (MIC90: 0.04 mg/l), cefotaxime (MIC90: 0.15 mg/l), azithromycin (MIC90: 0.015 mg/l), roxithromycin (MIC90: 0.05 mg/l) and quinupristin/dalfopristin (MIC90: 0.12 mg/l) gave the lowest MIC values. Minimal inhibibitory activity of amoxycillin (MIC90: 1.04 mg/l), cefixime (MIC90: 1.33 mg/l), cefoperazone (MIC90: 0.83 mg/l) tetracycline (MIC90: 0.29 mg/l) and minocycline (MIC90: 0.30 mg/l) was slightly lower, whereas borrelia were resistant to amikacin (MIC90: >128 mg/l). Mean minimal borreliacidal concentrations (MBCs) were representatively determined for piperacillin (MBC: 1.8 mg/l), ceftriaxone (MBC: 2.0 mg/l), azithromycin (MBC: 0.82 mg/ml), roxithromycin (MBC: 1.8 mg/l), quinupristin/dalfopristin (MBC: 5.0 mg/l), minocycline (MBC: 5.8 mg/l), and amikacin (MBC: >128 mg/l) by using conventional subculture for three weeks in combination with dark-field microscopy. B. garinii proved to be the most susceptible of the genospecies tested. Our study showed excellent in vitro antimicrobial activity of all classes of antibiotics tested, except the aminoglycosides and hence their suitability for therapy of Lyme disease.

Unexpected Antibiotic Susceptibility of a Chronic Isolate of Coxiella burnetiia

Evidence is mounting in support of the idea that different isolates of Coxiella burnetii, the etiologic agent of Q fever, are responsible for the distinct disease syndromes observed clinically. Recent studies have shown distinct antibiotic susceptibilities of different isolates of C. burnetii implicated in distinct clinical Q fever syndromes. With this in mind, we performed antibiotic susceptibility testing of the "S" isolate, a chronic-type isolate retrieved from a human patient with chronic disease. Antibiotics with differing efficacies upon the Nine Mile and Priscilla isolates were tested for their abilities to control acute and persistent "S" isolate infection of L-929 cells in vitro. The efficacies of doxycycline, rifampin, and three fluoroquinolone drugs--ciprofloxacin, ofloxacin, and norfloxacin--were tested. Compared to the chronic Q fever-implicated Priscilla isolate, which has been shown to exhibit a significant resistance to these antibiotics, the "S" isolate was much more susceptible. In persistently infected cells (greater than 300 d), the "S" isolate proved to be significantly more resistant to doxycycline, slightly more resistant to ciprofloxacin, slightly more susceptible to rifampin, and equally sensitive to ofloxacin and norfloxacin compared to the acute Q fever-implicated Nine Mile isolate. As with both the Nine Mile and Priscilla isolates, the "S" isolate was more susceptible to doxycycline, rifampin, and ofloxacin in recently infected cells (22 d) compared to cells having been persistently infected. With respect to the resistant nature of the chronic Q fever-implicated Priscilla isolate, as well as the lack of success in treating the "S" isolate in vivo, these results were unexpected. Such data supports an evolving hypothesis that the distinct C. burnetii isolates which may be responsible for the clearly different Q fever syndromes exhibit a spectrum of antibiotic susceptibility ranging from very susceptible (acute-implicate), Nine Mile isolate), to moderately susceptible (chronic-implicated "S" isolate), to moderately resistant (chronic-implicated Priscilla isolate).