Susceptibility Patterns Of Gram-negative Bacteria Research Articles

Antimicrobial Susceptibility Patterns of Gram-negative Bacteria, Gram-positive Bacteria and Fungi Species Isolated from Blood Culture Bottles in Yaounde, Cameroon

Antimicrobial Susceptibility Patterns of Gram-negative Bacteria, Gram-positive Bacteria and Fungi Species Isolated from Blood Culture Bottles in Yaounde, Cameroon

Prevalence and antibiogram of non-urinary isolates among patients attending a tertiary care hospital

Introduction and Aim: Gram-negative bacterial infections have emerged as a global health problem in clinical care. They account for the majority of community and hospital acquired infections which are resistant to various antimicrobials. The present study aimed to investigate the prevalence and antibiotic susceptibility pattern of Gram-negative bacteria (GNB) isolated from various non-urinary samples at a tertiary care hospital in Haryana. Materials and Methods: A total of 228 isolates were obtained from various clinical samples from January 2018 to July 2018 and were identified by standard bacteriological techniques. Antibiotic susceptibility testing was done using the disc diffusion technique by the Kirby Bauer method. Results: Adult patients showed higher isolation of GNB (31%) as compared to paediatric patients (16.3%). The most common GNB isolated from blood was Pseudomonas spp.(62%) and Klebsiella spp.(66.7%) from respiratory samples isolated in our study showed resistance to common antibiotics like gentamicin and ceftriaxone. Polymyxin B and Tigecycline were found to be sensitive. Conclusion: Strict compliance with antimicrobial stewardship policy should be followed to reduce the menace of antibiotic resistance.

Prevalence and Antimicrobial Susceptibility Pattern of Secondary Gram-negative Bacteria Isolated from Severe Acute Respiratory Syndrome Coronavirus Disease 2 Patients in A Tertiary Care Hospital

Prior to the Severe Acute Respiratory Syndrome Coronavirus Disease 2 (SARS-CoV-2) pandemic, the rise in antimicrobial resistance was a major source of concern in public health. However, due to the novelty of SARS-CoV-2 infection during the pandemic, antibiotics were administered prior to laboratory testing for secondary gram-negative bacteria (SGNB) in order to avoid or reduce the occurrence of SGNB infection. The purpose of this study was to investigate the etiology, prevalence, and antimicrobial susceptibility pattern of gram-negative bacteria (GNB) isolated from SARS-CoV-2 positive patients. Respiratory and blood samples were collected from confirmed SARS-CoV-2 positive patients. They were subsequently cultured and bacterial isolates identified according to standard microbiological protocols. Antimicrobial susceptibility testing (AST) was performed and interpreted according to Clinical & Laboratory Standards Institute (CLSI) 2021 guidelines. A total of sixty-four non-repetitive GNB were isolated from respiratory samples and twenty-two GNB from blood samples. K. pneumoniae was the major cause of SGNB, followed by Acinetobacter species. K. pneumoniae had over 60% resistance to β-Lactam combination agents, cephalosporin, and the carbapenem group of antibiotics. In the current study, we observed that K. pneumoniae was the major cause of SGNB and had high resistance to the antimicrobial agents. Hence, it is important that the epidemiology and susceptibility patterns of circulating organisms causing SGNB infection are always monitored to inform clinical treatment and decrease the occurrence of antibiotic-resistant bacteria.

Antibiotic susceptibility pattern of gram-negative bacteria isolated from apron and tables of meat vendors in Elele Market, Rivers State

Because of poor sanitary practices and a lack of knowledge about proper hygiene, meat vendors' aprons and tables could be potential sources of cross-infection of many public health bacteria. The purpose of this study was to determine the prevalence and antibiotic susceptibility of gram-negative bacteria isolates obtained from meat vendors' aprons and tables. 100 fresh swabs from meat vendors' aprons and tables were streaked on Eosin methylene blue, Cetrimide, and MacConkey agar and identified by the biochemical test. The antibiotic susceptibility pattern was evaluated on Mueller Hinton agar using the Kirby-Bauer disc diffusion method. Results: Out of the 100 samples processed, 66 Gram-negative bacteria were isolated. Klebsiella pneumoniae (74.24%) was the dominant gram-negative isolates, followed by E. coli (18.18%), Pseudomonas aeruginosa (4.55%), and Proteus sp (3.03%) respectively. The isolates from the tables recorded 100% resistance to Erythromycin and Cloxacillin with the highest sensitivity to Ofloxacin (66.7%) followed by Gentamicin (50%) while the isolates from aprons were 100% resistant to Augmentin and Cloxacillin followed by cefuroxime (93.3%) and Erythromycin (90%) with the highest sensitivity to Ofloxacin (100%) followed by Gentamicin (33.3%). This study confirmed the presence of multidrug-resistant gram-negative bacteria on the apron, and the levels of contamination detected on the aprons and tables used by meat vendors in Elele market presented an inadequate microbiological standard and quality. It is critical to implement proper orientation and workshops to educate meat vendors on standard practices to be followed when handling meat.

Antibiotic susceptibility pattern of gram-negative bacteria isolated from apron and tables of meat vendors in Elele Market, Rivers State

Antibiotic susceptibility pattern of gram-negative bacteria isolated from apron and tables of meat vendors in Elele Market, Rivers State

Antibiotic susceptibility patterns of gram-negative bacteria in the pediatric hematology-oncology ward of RSUD Dr. Soetomo, Surabaya

Infection is one of the causes of death in children with malignancy. Gram-negative bacteria with broad resistance to antibiotics are the cause of invasive infections in patients with malignancy. This prospective observational study was conducted by collecting medical record data, including the identity of patients, their diagnosis results, and the antibiotic susceptibility test results, from January to December 2020 in the pediatric hematology-oncology ward of Dr. Soetomo Regional General Hospital (hereinafter referred to as RSUD Dr. Soetomo), Surabaya. Positive cultures were obtained in 20.9% of the 196 samples. The growth of gram-negative bacteria was found in 48.8% of the positive culture test results, with a percentage of 50% in blood cultures, 30% in pus cultures, and 15% in urine cultures. The most common gram-negative bacteria isolates obtained in general were E. coli (40%) and K. pneumoniae (30%). The most commonly found non-fermenting gram-negative bacteria was P. aeruginosa (15%). The lowest antibiotic susceptibility was obtained to ampicillin (0%) and ampicillin-sulbactam 10%. The lowest antibiotic susceptibility was obtained to amikacin (85%) and cefepime (80%). The MDR resistance pattern was found in 80% of samples, 40% of which was found in ESBL-producing bacteria.

Antimicrobial Susceptibility Pattern of Gram-Negative Bacteria Causing Lower Respiratory Tract Infections in Kathmandu University Hospital.

Respiratory tract infection due to Gram-negative bacteria is a common cause of morbidity and mortality worldwide. This study was carried out to determine the antimicrobial susceptibility pattern of Gram-negative bacteria from patients with lower respiratory tract infection visiting Kathmandu University Hospital. A total of 3,403 respiratory samples including sputum and endotracheal aspirates were processed and antibiotic resistance pattern was determined following Clinical Laboratory Standard Institute guidelines. Patients' information was obtained after informed consent. Growth of Gram-negative bacteria was 210 (6.17%). 83(39.52%) were Klebsiella pneumoniae followed by Escherichia coli, Pseudomonas aeruginosa, Acinetobacter species, Klebsiella oxytoca, Enterobacter species, Proteus mirabilis and Haemophilus influenzae. 151(71.90%) isolates were multidrug resistant. None of the strains were resistant to colistin. 51(24.29%) were resistant to carbapenem and out of these 3(1.43%) were metallo-? lactamase producers. 89(65.92%) of the patients having both pneumonia along with other respiratory illnesses were above 60 years of age indicating that old age might be a predisposing factor. (p value is less than 0.0001). 92(81.42%) of patients of age above 60 years had multidrug resistant isolates indicating that old age might be a predisposing factor for getting infection my multidrug resistant isolates. (p value equals 0.0012) Among 36 diabetic patients 33(91.67%) had multidrug resistant isolates. Whereas out of 174 non-diabetic patients only 118(67.82%) had multidrug resistant isolates (p value equals 0.0037). Multidrug-resistant Gram negative bacteria were observed in respiratory samples. Effective treatment of lower respiratory tract infection need detailed microbiological diagnosis and drug susceptibility testing.

GRAM-NEGATIVE BACTERIA FROM PATIENTS WITH ENDOPHTHALMITIS: DISTRIBUTION OF ISOLATES AND ANTIMICROBIAL SUSCEPTIBILITIES.

To study the distribution of isolates and antimicrobial susceptibility of gram-negative bacteria among culture-positive vitreous samples from patients with endophthalmitis. The records from culture-positive vitreous isolates (endophthalmitis cases) during a 24-year period (December 1990 to December 2014), at the Microbiology Department of Bascom Palmer Eye Institute were reviewed. In the current study, gram-negative bacteria were reported in 246 (11.5%) of 2,134 vitreous isolates from endophthalmitis patients during 24-year period (December 1990 to December 2014) from a University Referral Center. The antimicrobial susceptibility to fluoroquinolones, aminoglycosides, carbapenems, and ceftazidime remained stable among gram-negative bacteria during the study period. Antibiotic susceptibility pattern of gram-negative bacteria from vitreous isolates did not change significantly during the 24-year study period.

Antibiotic Susceptibility Pattern of Gram-Negative Bacteria Isolated from Infected Wound of Patients in Two Health-Care Centers in Gboko Town

The rising cases of multi-drug resistant bacteria have received considerable attention from patients and clinicians as a result of difficulties encountered during treatment. This has posed great challenges to pharmaceutical practitioners for continued search for effective antibiotics. The present study aimed at investigating antibiotic susceptibility profile of Gram-negative bacteria isolated from infected wound in two selected privately owned healthcare centers in Gboko town. A total of thirty (30) wound samples, fifteen (15) from each of the hospital were collected using swab sticks and analyzed and the isolates tested for MDR using disc diffusion method. The result showed that the wounds were infected with Escherichia coli (46.7%), Salmonella spp (40%) and Pseudomonas spp (13.3%). The three isolates displayed varying degrees of resistance to antibiotics. Escherichia coli showed the highest resistance to streptomycin (92.8%), Augmentin (92.8%), Septrin (78%), Gentamycin (78.5%), Amoxacillin (71.4%) and Chloramphenicol (71.4%) and least resistance was observed with Pefloxacin (50%), Tarivid (50%), Sparfloxacin (57%), Ciprofloxacin (50%) antibiotics. Salmonella spp showed the highest resistance to Septrin (100%), Augmentin (91%), Streptomycin (91%), Amoxacillin (83.3%), Chloramphenicol (83.3%), Tarivid (83.3%) and least resistance to Sparfloxacin (33.3%), Ciprofloxacin (41.6%) and Pefloxacin (41.6%) antibiotics. Pseudomonas spp showed (100%) resistance to Gentamycin, Augmentin, Amoxacillin, Ciprofloxacin, Sparfloxacin, Septrin and Streptomycin, though the resistance was observed to be slightly minimal to Pefloxacin (75%), as well as Tarivid and Chloramphenicol. Antibiotic susceptibility test is recommended prior to administration of antibiotics for effective treatment and periodic monitoring is also advocated to check emerging MDR trends as a guide to health authorities.

Role of age and sex in determining antibiotic resistance in febrile urinary tract infections

To identify the age- and sex-specific antimicrobial susceptibility patterns of Gram-negative bacteria (GNB) in outpatient febrile urinary tract infections (UTIs) in Korea. A total 2262 consecutive samples collected from patients aged 1-101 years with febrile UTIs, during the period January 2012 to December 2014, were analyzed in this multicentre, retrospective cohort study. The sensitivities to cefotaxime and cefoxitin were over 85% for females but under 75% for males. Sex played an important role in the susceptibility of GNB to cefotaxime (p<0.001) and cefoxitin (p<0.001). The sensitivity to ciprofloxacin (age >20 years) was under 75% in both sexes, and was not influenced by sex (p=0.204). Age distributions of the incidences of resistance to cefotaxime, cefoxitin, and ciprofloxacin (age >20 years) were similar to the age distribution of the incidence of GNB, which indicates that the resistance patterns to these drugs were not affected by age (Kolmogorov-Smirnov test, female/male: p=0.927/p=0.509, p=0.193/p=0.911, and p=0.077/p=0.999, respectively). Age is not a considerable factor in determining the antibiotic resistance in febrile UTIs. Ciprofloxacin should be withheld from both sexes until culture results indicate its use. Second- or third-generation cephalosporins such as cefoxitin and cefotaxime can be used empirically only in females.

Antimicrobial susceptibility patterns of Gram-negative bacteria isolated in urinary tract infections in Venezuela: Results of the SMART study 2009-2012

Antimicrobial resistance of pathogens causing urinary tract infection (UTI) is a growing problem, which complicates their effective treatment. Surveillance is needed to guide appropriate empiric therapy. to describe the susceptibility patterns of Gram-negative bacteria isolated of patients with UTI to twelve antibiotics as part of the Study for Monitoring Antimicrobial Resistance Trends in Venezuela. Between 2009-2012 a total of 472 Gram-negative bacteria were isolated from hospitalized patients with UTI. The isolates were sent to Central Laboratory (Central Laboratory of International Health Management Associates) to confirm their identification, and to make susceptibility testing as recommended by the Clinical and Laboratory Standards Institute. Enterobacteriacea comprised 96.6% of the total, where Escherichia coli (76.9%) and Klebsiella pneumoniae (10.6%) were the most frequent. Extended-spectrum β-lactamases (ESBL) was detected in 21.6% of isolates. Top antimicrobial activity were ertapenem, imipenem, and amikacin (> 90.0%), slightly lower for amikacin (85.1%) in ESBL-producing strains. Resistance rates to fluoroquinolones and ampicillin/sulbactam were high (40 y 64%, respectively). These data suggest a necessary revision of the therapeutic regimens for the empirical treatment of UTI in Venezuela.

Antimicrobial susceptibility of Gram-negative organisms isolated from patients hospitalised with pneumonia in US and European hospitals: Results from the SENTRY Antimicrobial Surveillance Program, 2009–2012

Here we evaluated the frequency of occurrence and antimicrobial susceptibility patterns of Gram-negative bacteria isolated from patients hospitalised with pneumonia in medical centres in the USA (n=28) and Europe and the Mediterranean region (EMR) (n=25) in 2009–2012. Susceptibility testing was performed by reference broth microdilution methods. Overall, 12851 isolates were collected (6873/5978 in USA/EMR). The same top 11 organisms were observed in both geographic regions, but in different rank orders, and Gram-negative organisms represented 61.5/76.1% of strains in USA/EMR. Pseudomonas aeruginosa was the most frequently isolated Gram-negative organism in both regions (20.9/20.9% of cases in USA/EMR) and showed reduced susceptibility to most antimicrobials tested, including ceftazidime (79.6/68.7% susceptibility in USA/EMR), meropenem (76.3/65.8%) and piperacillin/tazobactam (72.9/63.9%). Klebsiella spp. was isolated from 9.7/11.6% of cases and showed extended-spectrum β-lactamase (ESBL) phenotype rates of 19.5/35.1% in USA/EMR. Meropenem and amikacin were active against 62.3/78.7% and 60.8/85.2% of ESBL phenotype Klebsiella spp. from USA/EMR, respectively. Enterobacter spp. ranked fourth in the USA (5.9%) and sixth in EMR (5.5%), whereas Escherichia coli ranked fifth in the USA (5.5%) and third in EMR (11.8%). Acinetobacter spp. and Stenotrophomonas maltophilia combined were isolated from 8.0/10.7% of cases in USA/EMR. A significant increase in P. aeruginosa susceptibility to meropenem and a significant decrease in gentamicin susceptibility among Klebsiella spp. were noted in EMR. These results confirm that very few agents remain broadly active against the most frequently isolated Gram-negative organisms from patients with pneumonia in US and EMR medical centres.

Antimicrobial susceptibility of Gram-negative organisms isolated from patients hospitalized in intensive care units in United States and European hospitals (2009–2011)

Treatment of infections in the intensive care unit (ICU) represents a great challenge, especially those caused by Gram-negative organisms. Rapid introduction of appropriate antimicrobial therapy is crucial to reduce mortality; resistance rates in the ICU can be elevated due to antimicrobial selection pressure. We evaluated the antimicrobial susceptibility patterns of Gram-negative bacteria isolated from patients hospitalized in ICUs (ICU patients). The isolates were consecutively collected as part of the SENTRY Antimicrobial Surveillance Program from January 2009 to December 2011 and tested for susceptibility to multiple antimicrobial agents at a central laboratory by reference broth microdilution methods. Antimicrobial susceptibility results for 5989 bacterial isolates from ICU patients (3445 from the United States [USA] and 2544 from Europe [EU]) were analyzed and compared to those of 17,244 organisms from non-ICU patients (9271 from USA and 7973 from EU). Escherichia coli, Klebsiella spp., and Pseudomonas aeruginosa were the most frequently isolated organisms from ICU patients, followed by Enterobacter spp., Serratia spp., Haemophilus influenzae, Acinetobacter spp., and Proteus mirabilis. Susceptibility rates were generally lower among ICU isolates compared to non-ICU organisms. E. coli isolates from ICU patients exhibited elevated extended-spectrum β-lactamase (ESBL)-phenotype rates (13.7% in USA and 16.6% in EU); furthermore, only amikacin (90.5–94.8% susceptibility), colistin (99.8–100.0% inhibited at ≤2 μg/mL), imipenem (95.5–96.0%), meropenem (95.4–95.8%), and tigecycline (96.3–98.0%) exhibited good activity against Klebsiella spp. ESBL-phenotype rates have increased among both E. coli and Klebsiella spp. from ICU patients in the USA and in Europe, with the most noticeable increase among Klebsiella spp. from Europe (from 27.5% in 2009 to 41.8% in 2011; P = 0.015 and odds ratio = 0.89 [95% confidence interval, 1.13–3.18]). Meropenem susceptibility among Klebsiella spp. improved slightly in the USA but decreased markedly in Europe from 100.0% in 2009 to 89.7% in 2011. Only colistin (99.4% susceptible) and amikacin (97.3% in USA and 84.9% in EU) exhibited good activity against P. aeruginosa strains from ICU patients. The greatest differences in susceptibility rates between P. aeruginosa strains from ICU and non-ICU patients were observed for the anti-pseudomonal β-lactams, such as ceftazidime, meropenem, and piperacillin/tazobactam. The results of this study (101 medical centers) highlight major antimicrobial coverage problems and trends in antimicrobial resistance for USA and EU ICU patient isolates.

Frequency of occurrence and antimicrobial susceptibility of Gram-negative bacteremia isolates in patients with urinary tract infection: results from United States and European hospitals (2009–2011)

We evaluated the frequency of occurrence and antimicrobial susceptibility patterns of Gram-negative bacteria isolated from bacteremic patients with UTI from European (EU) and United States (USA) hospitals during a 3-year period (2009–2011). Susceptibility testing was performed by the reference broth microdilution method on 2071 Gram-negative bacilli. The most frequently isolated pathogens were Escherichia coli (63·3/71·3% in USA/EU), Klebsiella spp. (16·7/11·2%) and Proteus mirabilis (6·4/5·0%). Escherichia coli susceptibility rates were generally similar in the USA and EU, with extended-spectrum beta-lactamase (ESBL)-phenotype rates at 8·1% in both regions. Among Klebsiella spp., ESBL rates varied from 11·4/17·1% in 2009 to 16·1/40·4% in 2011 in USA/EU, and susceptibility rates were generally lower in EU compared to the USA. Pseudomonas aeruginosa exhibited lower susceptibility rates to ceftazidime, meropenem and piperacillin/tazobactam in EU (78·4, 78·4 and 76·5%, respectively) compared to USA (91·2, 88·2 and 91·2%, respectively). In summary, very few antimicrobials provided satisfactory coverage (>90%) when tested against Klebsiella spp. and P. aeruginosa isolates in EU.

Antimicrobial susceptibility of Gram-negative bacteria in Brazilian hospitals: the MYSTIC Program Brazil 2003

Establish the susceptibility pattern of Gram-negative bacteria causing infections in ICU patients, MYSTIC Program Brazil 2003. Gram-negative bacteria (n = 1,550) causing nosocomial infections were collected at 20 Brazilian centers. The central laboratory confirmed the identification and performed the susceptibility tests by Etest methodology (AB Biodisk, Solna, Sweden) for meropenem, imipenem, ciprofloxacin, ceftazidime, cefepime, cefotaxime, piperacillin/tazobactam, gentamicin, and tobramycin. Interpretation criteria used were according to National Committee for Clinical Laboratory Standards (NCCLS). Pseudomonas aeruginosa (30.3%) was the most frequent isolate, followed by E. coli (18.6%), Klebsiella pneumoniae (16.9%), Acitenobacter baumannii (8.8%), and Enterobacter cloacae (7.1%). Pseudomonas aeruginosa (n=470) isolates presented susceptibility rates of 64% to meropenem, 63.8% to piperacillin/tazobactam, 63.4% to amikacin, 58.7% to imipenem. Acitenobacter baumannii presented susceptibility rates to meropenem of 97.1%, and 73% to tobramycin. E. coli and K. pneumoniae were highly susceptible to both carbapenems. Carbapenem resistance among the Enterobacteriaceae is still rare in the region. Acitenobacter baumannii and P. aeruginosa presented elevated resistance rates to all antimicrobials. Since they play an important role in nosocomial infections in this environment, the use of empirical combination therapy to treat these pathogens may be justified.

Antimicrobial susceptibility in intensive care units: MYSTIC Program Brazil 2002

Establish the susceptibility pattern of Gram-negative bacteria causing infections in ICU patients, MYSTIC Program Brazil 2002. Gram-negative bacteria (n = 503) causing nosocomial infections were collected at seven Brazilian centers. The central laboratory confirmed the identification and performed the susceptibility tests by E-test methodology (AB Biodisk, Solna, Sweden) for meropenem, imipenem, ciprofloxacin, ceftazidime, cefepime, cefotaxime, piperacillin/tazobactam, gentamicin, and tobramycin. Interpretation criteria used were according to National Committee for Clinical Laboratory Standards (NCCLS). Pseudomonas aeruginosa (33%) was the most frequently isolated, followed by A. baumannii (17.1%), K. pneumoniae (12.1%), E. coli (10.5%), and E. cloacae (7.9%). Pseudomonas aeruginosa isolates had susceptibility rates of 67.5% to piperacillin/tazobactam, 59.8% to meropenem, 57.3% to imipenem. A. baumannii presented susceptibility rates to meropenem of 89.5%, 88.4% to imipenem, and 74.4% to tobramycin. E. coli and K. pneumoniae were fully susceptible to both carbapenems. Carbapenem resistance among Enterobacteriaceae is still rare in this region. A. baumannii and P. aeruginosa presented elevated resistance rates to all antimicrobials. Since these two bacterial species play an important role in nosocomial infections, the use of empirical combination therapy to treat these pathogens may be justified.

Susceptibility patterns of Gram-negative bacteria from a Polish intensive care unit, 1997–2000

The susceptibility of Gram-negative bacterial strains ( n=400) isolated from clinical specimens of children hospitalized in a Polish intensive care unit (ICU) between 1997 and 2000 was tested. Meropenem, imipenem and ciprofloxacin were most active (>90% susceptibility) against the tested isolates, with no observed reduction in activity over 4 years. Extended-spectrum β-lactamases and AmpC β-lactamase producers among Enterobacteriaceae isolates from this ICU continued to be a serious therapeutic problem, although the carbapenems were highly active against these resistance phenotypes. Resistance to aminoglycosides (gentamicin, tobramycin) and ceftazidime was a characteristic of >40% of tested isolates.

Plasma Concentrations of Enrofloxacin in African Grey Parrots Treated with Medicated Water

Plasma concentrations of enrofloxacin were measured four times during a 7-day treatment period in African grey parrots that were fed with enrofloxacin-medicated drinking water. Water medicated at doubling doses of 0.09, 0.19, 0.38, 0.75, 1.5, and 3.0 mg/ml achieved mean concentrations (+/- SEM) of 0.10 (+/- 0.05), 0.12 (+/- 0.05), 0.12 (+/- 0.03), 0.15 (+/- 0.05), 0.30 (+/- 0.11), and 0.20 (+/- 0.06) micrograms/ml, respectively. A portion of the administered enrofloxacin was metabolized to an equipotent metabolite, ciprofloxacin. Mean ciprofloxacin concentrations paralleled enrofloxacin concentrations but were lower, ranging from 0.04 to 0.27 micrograms/ml. Acceptance of medicated water was adequate at lower doses; however, at doses of 1.5 and 3.0 mg/ml, acceptance was unsatisfactory, and mean weight loss in these groups was significantly higher than the control group. Based on the concentrations achieved in these preliminary trials and the susceptibility patterns of gram-negative bacteria isolated from psittacine birds, drinking water medicated with enrofloxacin at 0.19-0.75 mg/ml might be effective for treating highly susceptible gram-negative bacterial infections in African grey parrots.